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ROBERTO BERTOLANI
Professore emerito
Dipartimento Educazione e Scienze Umane
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Pubblicazioni
2023
- The Macrobiotus persimilis-polonicus complex (Eutardigrada, Macrobiotidae), another example of problematic species identification, with the description of four new species.
[Articolo su rivista]
Bertolani, Roberto; Cesari, Michele; Giovannini, Ilaria; Rebecchi, Lorena; Guidetti, Roberto; Kaczmarek, Łukasz; Pilato, Giovanni
abstract
In the phylum Tardigrada, as in other meiofauna taxa, the small size of the animals and the paucity of morphological characters useful for taxonomy present a challenge for systematic studies. For this reason, an integrated approach is increasingly desirable, including at least morphology, morphometry and molecular investigations, and possibly reproductive biology, ecology, physiology and other approaches. In this light, we analysed different populations of Macrobiotus (Eutardigrada, Macrobiotidae) from Italy, France and Poland with persimilis type of eggs and with very similar animals. We compared the morphology and morphometry of the type materials of Macrobiotus persimilis and Macrobiotus polonicus with those of newly collected populations, which were also analysed from a molecular (cox1 mtDNA and 18S rDNA) and reproductive perspective. Our data confirmed the presence of a persimilis-polonicus complex, recognizable by very similar characters of the animals and the eggs. It comprises M. persimilis, M. polonicus, four new morphologically distinguishable species described in this paper (Macrobiotus dolosus sp. nov., Macrobiotus siderophilus sp. nov., Macrobiotus fontourai sp. nov., Macrobiotus muralis sp. nov.) and other species very similar from a morphological point of view. Molecular data, retrieved for the first three new species, reveal that they have very high genetic distances for cox1 (16.0–17.7%). Furthermore, we have been able to verify that more than one species of this complex can cohabit in the same moss. A wider persimilis group, comprising the persimilis-polonicus complex, could also be identified only on morphological basis.
2021
- Integrative description of a new Tunisian tardigrade species, Macrobiotus azzunae sp. nov. (Eutardigrada, Macrobiotidae, hufelandi group)
[Articolo su rivista]
Ben Marnissi, Jamila; Cesari, Michele; Rebecchi, Lorena; Bertolani, Roberto
abstract
2020
- An integrated study of the biodiversity within the Pseudechiniscus suillus–facettalis group (Heterotardigrada: Echiniscidae)
[Articolo su rivista]
Cesari, Michele; Montanari, Martina; Kristensen, Reinhardt M; Bertolani, Roberto; Guidetti, Roberto; Rebecchi, Lorena
abstract
Pseudechiniscus is the second most species-rich genus in Heterotardigrada and in the family Echiniscidae. However, previous studies have pointed out polyphyly and heterogeneity in this taxon. The recent erection of the genus Acanthechiniscus was another step in making Pseudechiniscus monophyletic, but species identification is still problematic. The present investigation aims at clarifying biodiversity and taxonomy of Pseudechiniscus taxa, with a special focus on species pertaining to the so-called ‘suillus–facettalis group’, by using an integrated approach of morphological and molecular investigations. The analysis of sequences from specimens sampled in Europe and Asia confirms the monophyly of the genus Pseudechiniscus. Inside the genus, two main evolutionary lineages are recognizable: the P. novaezeelandiae lineage and the P. suillus–facettalis group lineage. Inside the P. suillus–facettalis group, COI molecular data points out a very high variability between sampled localities, but in some cases also among specimens sampled in the same locality (up to 33.3% p-distance). The integrated approach to the study of Pseudechiniscus allows confirmation of its monophyly and highlights the relationships in the taxon, pointing to its global distribution.
2019
- Actual checklist of Tardigrada species
[Banca dati]
Degma, Peter; Bertolani, Roberto; Guidetti, Roberto
abstract
More than one thousand Tardigrada species were included in the published checklist (Guidetti, R. & Bertolani, R. 2005. Tardigrade taxonomy: an updated check list of the taxa and a list of characters for their identification. Zootaxa, 845, 1–46.) plus the additions and corrections to this checklist (Degma, P. & Guidetti, R. 2007. Notes to the current checklist of Tardigrada. Zootaxa, 1579, 41–53.). For practical reasons, we have joined these two papers (without comments added to particular taxa as well as without references published in these papers) into an accurate combined version of the checklists. We incorporated all taxonomical novelties in the current edition of the Checklist even if they were published just online. Then, following the International Code of Zoological Nomenclature, we corrected the year of a taxon description according to its print edition. This checklist is free for all users, but utilization of it requires the citation of the two original papers. This checklist is the platform for occasional upgrades (date of latest upgrade is in the title). The changings respect to the previous version of the checklist have yellow background.
If you also use these changes, please also cite this checklist (please also cite this checklist (Degma, P. & Guidetti, R. Actual checklist of Tardigrada species. DOI: 10.25431/11380_1178608. Accessed date).
Please write us if you find any mistake or missing data in this checklist. Your help in its improvement will be acknowledged.
2019
- Dormancy in Freshwater Tardigrades
[Capitolo/Saggio]
Bertolani, Roberto; Guidetti, Roberto; Altiero, Tiziana; Nelson, Diane R.; Rebecchi, Lorena
abstract
For more than two centuries, tardigrades have been well known for their ability to undergo dormancy. However, this capability has been well studied mainly in the so-called limnoterrestrial species, i.e., in the species colonizing moist terrestrial habitats, such as mosses, lichens, and leaf litter. In these kinds of substrates, tardigrades are active only when a film of water is available around their body so in this condition they behave like aquatic animals. When the substrate dries or freezes, tardigrades achieve dormancy (quiescence) by entering cryptobiosis, specifically anhydrobiosis or cryobiosis, respectively. In freshwater habitats, both forms of cryptobiosis have been verified only in species able to live both in freshwater and terrestrial habitats. In the truly freshwater (or limnic) species, anhydrobiosis has not been verified, while cryobiosis has been confirmed in a few species. Another dormancy phenomenon bound to diapause is frequent in freshwater species: encystment (sometimes found even in limnoterrestrial species). The cyst state, which involves deep structural and physiological modifications, has been known from the beginning of the past century, but only recently has its morphology and inducing factors been studied in depth. Although data on molecular mechanisms allowing cryptobiosis are available, this information does not exist for encystment.
2019
- High diversity in species, reproductive modes and distribution within the Paramacrobiotus richtersi complex (Eutardigrada, Macrobiotidae)
[Articolo su rivista]
Guidetti, Roberto; Cesari, Michele; Bertolani, Roberto; Altiero, Tiziana; Rebecchi, Lorena
abstract
For many years, Paramacrobiotus richtersi was reported to consist of populations with different chromosome numbers and reproductive modes. To clarify the relationships among different populations, the type locality of the species (Clare Island, Ireland) and several Italian localities were sampled. Populations were investigated with an integrated approach, using morphological (LM, CLSM, SEM), morphometric, karyological, and molecular (18S rRNA, cox1 genes) data. Paramacrobiotus richtersi was redescribed and a neotype designed from the Irish bisexual population. Animals of all populations had very similar qualitative and quantitative characters, apart from the absence of males and the presence of triploidy in some of them, whereas some differences were recorded in the egg shell. All populations examined had the same 18S haplotype, while 21 haplotypes were found in the cox1 gene. In four cases, those qualitative characters were correlated with clear molecular (cox1) differences (genetic distance 14.6–21.8%). The integrative approach, which considered the morphological differences in the eggs, the reproductive biology and the wide genetic distances among putative species, led to the description of four new species (Paramacrobiotus arduus sp. n., Paramacrobiotus celsus sp. n., Paramacrobiotus depressus sp. n., Paramacrobiotus spatialis sp. n.) and two Unconfirmed Candidate Species (UCS) within the P. richtersi complex. Paramacrobiotus fairbanksi, the only ascertained parthenogenetic, triploid species, was redescribed and showed a wide distribution (Italy, Spain, Poland, Alaska), while the amphimictic species showed limited distributions. The difference in distribution between apomictic and amphimictic populations can be explained by the difference in the dispersal potentials associated with these two types of reproduction.
2019
- Increasing knowledge of Antarctic biodiversity: new endemic taxa of tardigrades (Eutardigrada; Ramazzottiidae) and their evolutionary relationships
[Articolo su rivista]
Guidetti, R.; Massa, Edoardo; Bertolani, R.; Rebecchi, L.; Cesari, M.
abstract
The underestimation of biodiversity and scarce knowledge of the biogeographic distributions of terrestrial meiofaunal component limit our understanding of the origin of Antarctic fauna. One of its main components is tardigrades; nonetheless studies on tardigrade diversity are still few in the continental Antarctic area. In order to increase our knowledge of the underreported terrestrial meiofaunal communities within continental Antarctica, as well as to provide new information for biogeographic and evolutionary analysis of these communities, the tardigrade diversity of 11 samples collected along the coast of Victoria Land was considered. The application of an integrative approach in which morphological (Light - LM, scanning electron - SEM, and confocal laser scanning microscopy - CSLM) and molecular analysis (18S, 28S, cox1 genes) were combined allowed us to characterize the tardigrade fauna inhabiting mosses, lichens, and cyanobacterial mats of Victoria Land. These analyses allowed the detection of two tardigrade species new to science (Cryoconicus antiarktos sp. nov., Ramazzottius sabatiniae sp. nov.), and the emendation of known species ((Hebesuncus ryani Dastych and Harris, 1994, Ramazzottius nivalis Dastych, 2006, Cryoconicus ljudmilae comb. nov. (Biserov, 1997/98), and Cryoconicus cataphractus (Maucci, 1974)), together with the genus Cryoconicus. The Ramazzottius type of claws was redefined identifying three subtypes. Also, we investigated the phylogenetic position of some problematic/unresolved lineages all belonging to the family Ramazzottiidae. These data increased the knowledge of the biodiversity in Victoria Land, the number of endemic tardigrades in Antarctica, and provided evidence on the origin of Antarctic endemism. Lastly, new methods for integrative taxonomic studies on tardigrades were presented and discussed.
2018
- Cytology and Cytogenetics
[Capitolo/Saggio]
Bertolani, Roberto; Rebecchi, Lorena
abstract
Several cytological aspects have been considered in tardigrades. Firstly,
the cell constancy which is not a true eutely being several mitoses present even after
hatching, even though some organs, such epidermis and nervous ganglia, have the
same cell number in juveniles and adults. The total number of these cells is speciesspecific.
Then the ultrastructure of cuticle, epidermis, feeding and digestive apparatus,
excretory and osmoregulatory organs, muscles, nerve cells, sensory cells and
storage cells has been considered. Instead, the ultrastructure of the germ cells has
been considered in the chapter on reproduction. With regard to chromosome number
and shape, it has been observed that generally there is little difference among the
species (n ¼ 5 or n ¼ 6), but several cases of polyploid populations exist, often very
similar to diploid populations from a morphological point of view. In most cases the
polyploid populations do not have males and reproduce by apomixis. Studies on the
genome size have confirmed the presence of polyploid populations, as well as the
presence of nuclei with multiple amounts of DNA within the same specimen. The
genome size of the tardigrades is always relatively small and does not seem related to
phylogenetic lineages. Studies on tardigrade genomes have placed this phylum at the
centre of discussions on the evolution of Metazoa and have considered the role of
horizontal gene transfer in animal evolution with contrasting results.
2018
- Paleontology and Molecular Dating
[Capitolo/Saggio]
Guidetti, Roberto; Bertolani, Roberto
abstract
Few fossil tardigrade records are known, probably due to their minute size
and absence of consistent hard body parts. A possible but not certain tardigrade
ancestor was found as an “Orsten”-type secondarily phosphatized fossil from the
Middle Cambrian limestone. It is characterized by only three pairs of legs as a
possible consequence of a plesiomorphic anameric ontogeny that led to four leg
segments in the extant tardigrades. Its other characters, related to claw and cuticle
morphologies, resemble those of heterotardigrades. The first findings of sure tardigrades
come from Cretaceous amber, in which the species Beorn leggi and
Milnesium swolenskyi were found. These species, and especially the latter, evidence
that more than 90 million years ago, “modern” tardigrades already existed, and only
few morphological differences, mainly related to morphometric tracts, occur with
respect to known modern species. Quaternary subfossils of tardigrades have been
found with palynological studies during paleoecology researches. They have been
recorded mainly in polar regions and classified within the non-pollen palynomorphs
category. Cuticular remains of animals and eggs can persist in the substrates for very
long time, so tardigrades can be used as paleoclimatic bioindicators, but despite their
potentiality, a few studies have focused to find these organisms in microfossil
samples and in sediments for paleoecological studies.
For estimating the dates of phylogenetic events related to the origin of tardigrades
and/or their evolutionary lineages, molecular clock analyses have been used. Molecular
data indicate that the origin of the phylum should be posed during or before the
Cambrian period, placing the origin of Tardigrada in marine environment and their
terrestrialization not before that of other ecdysozoans.
2017
- Comparative analyses of Bertolanius species (Eohypsibiidae; Eutardigrada) with the description of Bertolaniusbirnae sp. nov. from northern polar regions
[Articolo su rivista]
Hansen, Jesper Guldberg; Kristensen, Reinhardt Møbjerg; Bertolani, Roberto; Guidetti, Roberto
abstract
Species of the genus Bertolanius (Eohypsibiidae, Eohypsibioidea) are morphologically very similar and can be distinguished by only minute differences. During faunal surveys in Arctic areas (Disko I., Greenland; Uummannaq, Greenland; Abisko, Sweden), the four species Bertolanius nebulosus, Bertolanius smreczynskii, Bertolanius weglarskae and Bertolanius birnae sp. nov. were found. Bertolanius nebulosus and Bertolaniussmreczynskii have been compared with their paratypes, and type material of other species of Bertolanius has been considered for comparison within the genus. Bertolaniusbirnae sp. nov. possesses a unique combination of characters (i.e., an evident anterior band of teeth, the median ridge of the buccal armature consisting of two large teeth instead of one, absence of eyes, and eggs with conical processes without areolation around their bases) that is not seen in any other species in the genus, though these characters may be present in other combinations within the genus. Our revision and analytical comparison among these Bertolanius species adds new and important information on claw, buccal armature, egg surface morphologies as well as the encystment process of the species. We also provide a taxonomic key to aid the identification of Bertolanius species. The new discoveries of Bertolanius species from northern polar regions further support the hypothesis that the distribution of Eohypsibioidea is restricted to the Holarctic in the Arctic and Periarctic areas, or in alpine areas between 550 and 2400 m a.s.l. of more temperate regions.
2016
- Genetic diversity and biogeography of the south polar water bear Acutuncus antarcticus (Eutardigrada : Hypsibiidae) – evidence that it is a truly pan-Antarctic species
[Articolo su rivista]
Cesari, Michele; Mcinnes, J. Sandra; Bertolani, Roberto; Rebecchi, Lorena; Guidetti, Roberto
abstract
Antarctica is an ice-dominated continent and all its terrestrial and freshwater habitats are fragmented, which leads
to genetic divergence and, eventually, speciation. Acutuncus antarcticus is the most common Antarctic tardigrade and its cryptobiotic capabilities, small size and parthenogenetic reproduction present a high potential for dispersal and colonisation. Morphological (light and electron microscopy, karyology) and molecular (18S rRNA and cytochrome c oxidase subunit I (COI) genes) analyses on seven populations of A. antarcticus elucidated the genetic diversity and distribution of this species. All analysed populations were morphologically indistinguishable and made up of diploid females. All specimens presented the same 18S rRNA sequence. In contrast, COI analysis showed higher variability, with most Victoria Land populations presenting up to five different haplotypes. Genetic distances between Victoria Land specimens and those found elsewhere in Antarctica were low, while distances between Dronning Maud Land and specimens from elsewhere were high. Our analyses show that A. antarcticus can still be considered a pan-Antarctic species, although the moderately high genetic diversity within Victoria Land indicates the potential for speciation events. Regions of Victoria Land are considered to have been possible refugia during the last glacial maximum and a current biodiversity hotspot, which the populations of A. antarcticus mirror with a higher diversity than in other regions of Antarctica.
2016
- Integrative systematic studies on tardigrades from Antarctica identify new genera and new species within Macrobiotoidea
and Echiniscoidea
[Articolo su rivista]
Vecchi, Matteo; Cesari, Michele; Bertolani, Roberto; Jonsson, K. Ingemar; Rebecchi, Lorena; Guidetti, Roberto
abstract
Tardigrades represent one of the most abundant groups of Antarctic metazoans in terms of abundance and
diversity, thanks to their ability to withstand desiccation and freezing; however, their biodiversity is underestimated.
Antarctic tardigrades from Dronning Maud Land and Victoria Land were analysed from a morphological point of view
with light microscopy and scanning electron microscopy, and from a molecular point of view using two genes (18S, 28S)
analysed in Bayesian inference and maximum-likelihood frameworks. In addition, indel-coding datasets were used
for the first time to infer tardigrade phylogenies. We also compared Antarctic specimens with those from Italy and
Greenland. A combined morphological and molecular analysis led to the identification of two new evolutionary lineages,
for which we here erect the new genera Acanthechiniscus, gen. nov. (Echiniscidae, Echiniscoidea) and Mesobiotus, gen. nov.
(Macrobiotidae, Macrobiotoidea). Moreover, two species new to science were discovered: Pseudechiniscus titianae,
sp. nov. (Echiniscidae : Echiniscoidea) and Mesobiotus hilariae, sp. nov. (Macrobiotidae : Macrobiotoidea). This study
highlights the high tardigrade diversity in Antarctica and the importance of an integrated approach in faunal and taxonomic
studies.
2016
- Interspecific relationships of tardigrades with bacteria, fungi and protozoans, with a focus on the phylogenetic position of Pyxidium tardigradum (Ciliophora)
[Articolo su rivista]
Vecchi, Matteo; Vicente, Filipe; Guidetti, Roberto; Bertolani, Roberto; Rebecchi, Lorena; Cesari, Michele
abstract
Symbiosis can be defined as an interaction between individuals of different biological species. Despite the small
number of studies solely devoted to symbiotic interactions between tardigrades and micro-organisms (such as
bacteria, fungi and protozoans), numerous reports can be found in the literature, especially as notes in faunal
and alpha-taxonomy studies. Here, we review the literature and compile a list of the interactions between
tardigrades and micro-organisms, excluding those that constitute food for tardigrades. Furthermore, a genetic
study on a tardigrade symbiophoront, the ciliate Pyxidium tardigradum van der Land, 1964 was performed.
There are a few records of P. tardigradum on both European and Asian tardigrades, but no morphological
discrepancies among populations have been observed. We present here the phylogenetic positioning for
P. tardigradum inferred by using nuclear ribosomal markers (18S and 5.8S). The phylogenetic trees showed all
P. tardigradum specimens grouped together, and belonging to the family Operculariidae, order Operculariida.
Moreover, a study based on the genetic distances between a Portuguese and an Irish population of
P. tardigradum was performed using internal transcribed spacers ITS1 and ITS2. The ITS1 and ITS2 sequences
showed differences between populations, leading us to hypothesize the presence of cryptic species.
2016
- Morphological and molecular analyses on Richtersius (Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea
[Articolo su rivista]
Guidetti, Roberto; Rebecchi, Lorena; Bertolani, Roberto; Jönsson, K. Ingemar; Kristensen, M. Reinhardt; Cesari, Michele
abstract
Important contributions have been made to the systematics of Eutardigrada in recent years, but these have also
revealed that several taxa are polyphyletic and that cryptic species are present. To shed light on the taxonomy
and systematic position of the genus Richtersius (Eutardigrada, Macrobiotoidea), six populations attributed to
Richtersius coronifer were collected and analysed from morphological (light and scanning electron microscopy)
and molecular (mitochondrial cytochrome oxidase subunit 1, 18S, 28S) points of view. In particular, a new
morphometric index (claw common tract: length of the common tract of the claw/total claw length 9 100) and a
new morphological character (stalk system) were introduced. Our integrative study was able to unveil the
‘cryptic’ species diversity within Richtersius, showing that the genus contains more than one evolutionary
lineage. A morphological peculiarity in the animals of all lineages is the dimorphism in the morphology of the
cuticle. Cuticular pores are present in the newborns and are lost with the first moult; this morphological change
represents a novelty in the life cycle of eutardigrades. The phylogenetic analyses carried out on Richtersius
populations and other Macrobiotoidea show that Richtersius is closely related to Macrobiotus islandicus, whereas
Adorybiotus granulatus is more related to Richtersius and M. islandicus than to other members of the genus
Macrobiotus (type genus of Macrobiotidae); therefore, the genus Macrobiotus and the family Macrobiotidae are
not monophyletic. Based on these results, the new genus Diaforobiotus (for M. islandicus) and the new family
Richtersiidae (composed of Richtersius, Diaforobiotus gen. nov., and Adorybiotus) are established.
2016
- What if the claws are reduced? Morphological and molecular phylogenetic relationships of the genus Haplomacrobiotus May, 1948 (Eutardigrada, Parachela)
[Articolo su rivista]
Cesari, Michele; Vecchi, Matteo; Palmer, Aparna; Bertolani, Roberto; Pilato, Giovanni; Rebecchi, Lorena; Guidetti, Roberto
abstract
Eutardigrada systematics relies mainly on the morphology of the sclerified structures of the animals. In
particular, the main division of Parachela into four superfamilies relies heavily upon claw morphology; however,
this character, alone, may be either inadequate or useless for tardigrades with no claws, or when secondary claw
branches are reduced or absent, as in the case of species belonging to the genus Haplomacrobiotus. This is a very
uncommon genus, so far reported only in North America. The systematic position of this genus has been debated
since its description, having first been placed in the family Macrobiotidae (Macrobiotoidea) and then in the family
Calohypsibiidae (Hypsibioidea). Currently, the position of the supposedly related genus Hexapodibius is still
debated, being attributed to Isohypsibiidae (Isohypsibioidea) or to Calohypsibiidae (Hypsibioidea), i.e. to two
different superfamilies. The morphological (light and electron microscopy), chemical (X–ray spectroscopy), and
molecular (18S and 28S genes) analyses of a population of Haplomacrobiotus utahensis Pilato & Beasley, 2005
from Snow Canyon State Park (Utah, USA) allowed us to validate the position of this genus within
Isohypsibioidea. Our integrated findings placed Haplomacrobiotus in a close relationship with the genus
Hexapodibius, and allowed us to erect the new family Hexapodibiidae, comprising the genera Hexapodibius,
Parhexapodibius, Haplomacrobiotus, and Haplohexapodibius.
2015
- Distribution of Calcium and Chitin in the Tardigrade Feeding Apparatus in Relation to its Function and Morphology
[Articolo su rivista]
Guidetti, Roberto; Bonifacio, Alois; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena
abstract
The cuticular portion of the tardigrade feeding apparatus is a complex structure that can be schematically divided into four parts: a buccal ring, a buccal tube, a stylet system (formed by two piercing stylets, each within a stylet coat, and two stylet supports), and the lining of a myoepithelial sucking pharynx. To better understand the function and evolution of the feeding apparatus, the morpho-functional traits and chemical composition of the structures forming the feeding apparatuses of eight different species of tardigrades were analyzed. These eight species are representative of almost all main phylogenetic lineages of the phylum. The calcium and chitin in the feeding apparatus were examined by light microscopy (LM), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), energy dispersive X-ray spectroscopy (EDX), and Raman microspectroscopy (Raman). In all species, the feeding apparatus had been subjected to biomineralization due to CaCO3 encrustations organized in the crystalline form of aragonite. Aragonite and chitin are present in different concentrations in the feeding apparatus according to the structures and species considered. Generally, where the structures are rigid there is more aragonite than chitin, and vice versa. The buccal tube and piercing stylets are rich in calcium, with the piercing stylets apparently composed exclusively of aragonite. In eutardigrades, chitin is in higher concentration in the structures subject to higher mechanical stresses, such as the crests of the buccal crown and the condyles of the stylet furca.
2014
- Aquatic tardigrades in the Great Smoky Mountains National Park, North Carolina and Tennessee, U.S.A., with the description of a new species of Thulinius (Tardigrada, Isohypsibiidae)
[Articolo su rivista]
Bertolani, Roberto; PAUL J., Bartels; Guidetti, Roberto; Cesari, Michele; DIANE R., Nelson
abstract
As part of the All Taxa Biodiversity Inventory (http://www.dlia.org), an extensive survey of tardigrades has been conducted in the Great Smoky Mountains National Park (GSMNP) in Tennessee and North Carolina, U.S.A., by Bartels and Nelson. Freshwater tardigrades include three species in the aquatic genus Thulinius (Eutardigrada, Isohypsibiidae). A new species, Thulinius romanoi, described from stream sediment, is distinguished from all other congeners by having a sculptured cuticle. In addition, the presence of Thulinius augusti (Murray, 1907) was verified by combined orphological and molecular analysis, and nine specimens of a third species, Thulinius cf. saltursus, were also found. Thulinius augusti is a
new record for the United States. Thulinius saltursus (Schuster, Toftner & Grigarick, 1978) was previously recorded in California and Ohio, but our specimens vary slightly in morphology. The list of tardigrades from streams in the GSMNP was updated to a total of 44 species, 22 of which were predominantly or exclusively aquatic.
2014
- Biodiversity and adaptive strategy to Antarctica: the tardigrades
[Abstract in Atti di Convegno]
Vecchi, Matteo; Mcinnes, Michele Cesari Sandra; Giovannini, Ilaria; Altiero, Tiziana; Rebecchi, Lorena; Bertolani, Roberto; Guidetti, Roberto
abstract
Tardigrades are important members of the Antarctic biota in terms of abundance, distribution, and colonized substrates. Despite their importance and regular occurrence in the harsh Antarctic terrestrial ecosystems, there have been few ecological or taxonomic studies. We carried out an extensive sampling campaign along Victoria Land coastal line, collecting 180+ samples of lichens, mosses and freshwater sediments over a c. 600 km North–South transect. These samples revealed an unexpectedly high diversity: 14 species, four of which new for science.
Our results have underlined the level of undiscovered biodiversity in Antarctica. Some species had very localized distribution and occurred in specific substrates (e.g. moss or lichen). Other species were more scattered, and one (the endemic Acutuncus antarcticus) was present in almost all sampling areas and substrate types. This situation indicates that, as in temperate areas, Antarctica has tardigrade species with low dispersal capabilities, and a few species with high dispersal capabilities. Surprisingly, the genetic variability of A. antarcticus (COI gene) was extremely low even between very distant populations.
Laboratory experiments on the adaptive strategy of A. antarcticus indicated a very short life cycle (c. 3-4 months), shorter than in species from temperate regions. Moreover, A. antarcticus exhibits thelytoky and has cryptobiotic capabilities. These attributes allowed this species to colonize almost all viable habitats in Antarctica
2014
- Phylogeny of Eutardigrada: new molecular data and their morphological support lead to identification of new evolutionary lineages
[Articolo su rivista]
Bertolani, Roberto; Guidetti, Roberto; Marchioro, Trevor; Altiero, Tiziana; Rebecchi, Lorena; Cesari, Michele
abstract
Seventy-nine specimens belonging to six of the nine current eutardigrade families have been considered in a wide and extensive study of the phylogeny of the largest class of Tardigrada (Eutardigrada). The molecular (18S rDNA) and morphological data partly support previous results. In particular, the applied integrative approach allowed us to find morphological synapomorphies, supporting the clusters here identified by molecular data and the previous taxa erected only on molecular basis. The class Eutardigrada has been confirmed and, within it, the orders Apochela and Parachela, the superfamilies Macrobiotoidea, Hypsibioidea and Isohypsibioidea, and all the families and subfamilies considered, even though in several cases with an emended diagnosis. In addition, new taxa have been erected: the superfamily Eohypsibioidea, the new families Hexapodibiidae and Isohypsibiidae, the new subfamily Pilatobiidae (Hypsibiidae) with the new genus Pilatobius, in addition to an upgrading to genus level of Diphascon and Adropion, to date considered subgenera of Diphascon. Our results demonstrate that while molecular analysis is an important tool for understanding phylogeny, an integrative approach using molecular and morphological data is necessary to fully elucidate evolutionary relationships.
2014
- The value of the integrative approach in tardigrade taxonomy: the case study of an Antarctic eutardigrade.
[Abstract in Rivista]
Bertolani, Roberto; Cesari, Michele; Vecchi, Matteo; Rebecchi, Lorena; Guidetti, Roberto
abstract
The use of the molecular approach in tardigrades has recently widespread for identifying taxa and evolutionary lineages. Firstly, it has been utilized for identifying the phylum position within Ecdysozoa and then to recognize both its evolutionary lineages and species. As regards phylogeny, in several cases a good correspondence between molecular and morphological data was found, but in others results were contrasting. For example, the Eutardigrada genera Hypsibius and Isohypsibius, which have two different types of claws sharing asymmetry with respect to the median plane of the leg, were considered belonging to the same subfamily, and 50 years ago subgenera of the same genus, Hypsibius. Molecular data have pointed out that these two genera belong to different superfamilies (Hypsibioidea and Isohypsibioidea). Other genera were attributed to one or the other superfamily according to the morphology of their claws, attributions always confirmed when molecular support was obtained.
In Antarctica we found tardigrades with claws attributable to Ramajendas (Isohypsibioidea, Isohypsibiidae) for the particular length of the main branch of the external claw and its weak connection to the basal tract. Ramajendas is only from Antarctica and surrounding austral areas. We also found other specimens, belonging to Ramazzottius and Hebesuncus (Hypsibioidea, Ramazzottiidae). This material allowed us to carry out an integrative approach, obtaining both molecular data (18S and 28S genes) and new morphological information.
Both Bayesian and maximum likelihood cladograms clearly placed the specimens with putative Ramajendas claws together with Hebesuncus and Ramazzottius, within the Ramazzottiidae family. New morphological data on the specimens with putative Ramajendas claws evidenced that, like in Ramazzottius, there are two elliptical structures on the head and the eggs are ornamented and laid freely (on the contrary, in all Isohypsibioidea the eggs are smooth shelled and laid within the exuvium). Therefore, both approaches evidence that the specimens do not belong to Ramajendas (and consequently not to Isohypsibioidea), as previously supposed, even though they share their particular shape of the external claw with Ramajendas, evidently due to adaptive convergence. They belong to Hypsibioidea and in particular to a new species of Ramazzottius. These results confirm the importance of the integrative approach in dealing with Tardigrada identification and phylogeny.
2013
- A DNA barcoding approach in the study of tardigrades
[Articolo su rivista]
Cesari, Michele; Guidetti, Roberto; Rebecchi, Lorena; Giovannini, Ilaria; Bertolani, Roberto
abstract
DNA barcoding is a technique proposed by Hebert and coworkers in 2003 for discriminating species through analysis of a single gene barcode locus. It aims to obtain a better taxonomic resolution than that achieved through morphological studies, and to avoid the decline in taxonomic knowledge. Today DNA barcoding is a global enterprise, and the implementation of the idea has seen a rapid rise (more than 1900 papers published to date on different organisms). Nonetheless, controversy still arises regarding barcoding and taxonomy. It is important to note that DNA barcoding does not focus on building a tree-of-life or on doing DNA taxonomy, even though sometimes it has been used for these purposes. DNA barcoding rather focuses on producing a universal molecular identification key based on strong taxonomic knowledge that should be included in the barcode reference library. In the phylum Tardigrada, DNA barcoding represents a recent approach to species identification and to help in solving taxonomic problems, especially considering the diminutive size of these animals and the paucity of morphological characters useful for taxonomy. In the framework of the MoDNA Project (Morphology and DNA), carried out by our research group in collaboration with several colleagues, we are combining the study of a fragment of the mitochondrial cytochrome c oxidase subunit I gene (cox1) with morphological data, in a wide sense (cuticular structures, chromosomes, data on sex ratio and reproduction), to form an integrative taxonomy approach for tardigrade species identification. We believe that without verified reference sequences from voucher specimens that have been authenticated by qualified taxonomists, there is no reliable library for newly generated sequences with which to be compared. Methods and protocols for standardized results are focused on obtaining tight correspondence between tardigrade morphology (and egg shell morphology, when useful), possibly both light and scanning electron microscopy images, and molecular sequence. This approach is particularly useful in describing new species, and important when applied on material collected in species type localities. Results using this approach are presented, primarily focusing on a number of species from the so-called “Macrobiotus hufelandi group”.
2013
- Comparative analysis of the tardigrade feeding apparatus: adaptive convergence and evolutionary pattern of the piercing stylet system
[Articolo su rivista]
Guidetti, Roberto; Bertolani, Roberto; Rebecchi, Lorena
abstract
A thorough analysis of the cuticular parts of tardigrade feeding apparatuses was performed in order to provide a more complete understanding of their evolution and their potential homologies with other animal phyla (e.g. Cycloneuralia and Arthropoda). The buccal-
pharyngeal apparatuses of eight species belonging to both Eutardigrada and Heterotardigrada were studied using light and scanning electron microscopy. This study supports and completes a previous study on the relationships between form and function in the buccalpharyngeal apparatus of eutardigrades. The common sclerified structures of the tardigrade buccal-pharyngeal apparatus are: a buccal
ring connected to a straight buccal tube, a buccal crown, longitudinal thickenings within the pharynx, and a stylet system composed of piercing stylets within stylet coats, and stylet supports. Specifically, heterotardigrades (Echiniscoidea) have a narrow buccal tube; long piercing stylets, each with a longitudinal groove, that cross one another before exiting the mouth; pharyngeal bars and secondary longitudinal
thickenings within the pharynx. In contrast, eutardigrades have stylets which are shorter than the buccal tube; Parachela
have pharyngeal apophyses and placoids within the pharynx, while Apochela lack a buccal crown and cuticular thickenings within the pharynx, the buccal tube is very wide, and the short stylets are associated with triangular-shaped stylet supports. In both classes, when the piercing stylet tips emerge from the mouth to pierce food, the buccal tube opening is almost completely obstructed, which may hinder food uptake. In heterotardigrades, the crossing of the piercing stylets may further decrease food uptake, however this disadvantage may have been reduced in echiniscids by the evolution of a long buccal tube and long stylets able to run more parallel to the buccal tube. In contrast, eutardigrades evolved different strategies. In the order Apochela and in several Itaquasconinae (Parachela), the buccal tube is wide, the stylets are short and run parallel to the tube without crossing. In other Parachela, the piercing stylets do not cross one another because they are curved. Further, the development of an anterior bend in the buccal tube (e.g. in Doryphoribius and Macrobiotoidea) may allow the shift of the stylet sheaths to a more ventral position so that a wide portion of the mouth is free during the
piercing stylet movements. The possible convergent evolution of several structures of the buccal-pharyngeal apparatus (e.g. ventral lamina, pharyngeal tube, wide buccal tube without buccal crown, buccal lamellae) was analysed and discussed.
2013
- Considerations on the taxonomy of the Phylum Tardigrada
[Articolo su rivista]
Filipe, Vicente; Bertolani, Roberto
abstract
An analysis of the taxonomy of the Tardigrada is offered, based on the latest checklist version. A total of 1167 species
from 113 genera were counted, but marine species are misrepresented on account of being understudied. Moreover, many
poor descriptions and synonyms remain in this constantly growing list. We advocate more accurate future taxonomic
work, aiming for an official list of species that better represents true values of biodiversity.
2013
- Diversità genetica e distribuzione geografica in una specie pan antartica: Acutuncus antarcticus (Tardigrada, Hypsibiidae
[Abstract in Rivista]
Cesari, Michele; Mcinnes, S.; Bertolani, Roberto; Mori, L.; Rebecchi, Lorena; Guidetti, Roberto
abstract
L’origine della fauna continentale antartica è oggetto di ampia discussione. La distribuzione dei vari taxa potrebbe essere il risultato di una dispersione in atto (recolonization hypothesis), oppure di una distribuzione Gondwaniana (glacial refugia hypothesis). Entrambe le ipotesi mancano però di conferme, considerando anche le scarse conoscenze sulla fauna invertebrata antartica.
Per trovare prove a favore di una o dell’altra ipotesi è stata quindi iniziata l’analisi della diversità genetica e della distribuzione dei tardigradi, uno dei taxa più rappresentati nella fauna antartica continentale. Sono stati analizzati esemplari della specie endemica Acutuncus antarcticus (Eutardigrada, Hypsibiidae), campionati in sedimenti di pozze permanenti o semipermanenti provenienti da 7 località poste lungo un transetto nord-sud in Terra Vittoria. I due punti di campionamento più vicini tra loro distavano circa 23 km, mentre i più lontani circa 622 km. Per 65 esemplari sono state ottenute le sequenze dei geni 18S e cox1, che sono poi state analizzate insieme alle corrispondenti sequenze disponibili in GenBank e BOLD. E’ stata calcolata la diversità genetica e aplotipica tra individui (p-distance, Kimura 2-parametri) e tra popolazioni (diversità genetica di Nei, FST, numero di migranti) e costruita una rete di aplotipi. Su alcune popolazioni è stata inoltre effettuata l’analisi cariologica e valutata la sex ratio.
Tutti gli individui (analizzati ex novo o disponibili nelle banche dati) sono risultati appartenere alla stessa specie: essi presentavano la stessa sequenza per il gene 18S e soprattutto una distanza genetica per il gene cox1 minore del 5%. La maggior parte delle popolazioni presentava più aplotipi, con l’eccezione di quelle situate nella parte più a nord del transetto, che sono risultate omogenee. Alcuni aplotipi risultavano presenti in diverse località anche distanti tra loro. Le popolazioni, sempre formate da sole femmine (2n= 12/14), sono geneticamente differenziate, ad eccezione di quelle situate nella parte centrale del transetto. Acutuncus antarcticus risulta essere una specie panantartica molto diffusa, in ambiente dulciacquicolo. Le popolazioni con maggiore variabilità genetica sono in concomitanza con l’hotspot di biodiversità individuato sulle coste di Terra Vittoria, che si ipotizza sia servito da glacial refugium durante gli eventi di glaciazione che caratterizzano il continente.
2013
- Effetti delle radiazioni ultraviolette e della temperatura su un organismo della meiofauna antartica: Acutuncus antarcticus (Eutardigrada).
[Abstract in Rivista]
Altiero, Tiziana; Guidetti, Roberto; Giovannini, Ilaria; Cesari, Michele; Montorfano, G.; Rizzo, A. M.; Bertolani, Roberto; Rebecchi, Lorena
abstract
I cambiamenti climatici in atto, oltre ad aumentare la temperatura, riducono la quantità di ozono troposferico. Questo porta ad un aumento delle radiazioni ultraviolette (UV), con potenziali conseguenze negative sulla salute umana e sugli ecosistemi. Tardigradi e rotiferi, principali componenti della meiofauna terrestre antartica, sono molto vulnerabili agli effetti sinergici di temperatura e UV, in quanto la loro stagione di sviluppo coincide con il periodo primaverile antartico, in cui normalmente si ha una diminuzione dell’ozono.
Sono state quindi analizzate le risposte fisiologiche e biochimiche all’incremento di temperatura e UV nell’eutardigrado Acutuncus antarcticus, una delle specie più abbondanti nelle briofite e nei piccoli invasi di acqua dolce dell’Antartide.
Esperimenti di essiccamento in condizioni controllate hanno evidenziato che A. antarcticus è in grado di attuare l’anidrobiosi, mostrando un’elevata sopravvivenza (92,8%), insolita per una specie di tardigrado generalmente dulciacquicola. Gli antiossidanti non sembrano però essere responsabili di tale sopravvivenza in quanto, ad eccezione della catalasi, non sono emerse differenze significative nell’attività/quantità di antiossidanti tra esemplari idratati e secchi, a differenza di quanto osservato in Paramacrobiotus richtersi, una specie di tardigrado prettamente “terrestre” che vive in zone temperate. Esperimenti tesi a valutare la resistenza di esemplari attivi di A. antarcticus all’incremento della temperatura (da 8°C a 41°C) hanno dimostrato che la specie è in grado di tollerare temperature elevate (a 33°C = 100% vivi; a 37°C = 35% vivi), anche se per breve tempo. Entrambi gli stati fisiologici (idratato ed essiccato) di A. antarcticus hanno dimostrato una buona resistenza alle radiazioni UV. Gli esemplari idratati hanno resistito fino alla dose di 61,9 kJ m-2 (5% vivi), mentre quelli in stato essiccato fino alla dose di 74,8 kJ m-2(7,5% vivi). Negli animali attivi, alla LD50 di 28,6 kJ m-2, l’effetto negativo degli UV aumenta in combinazione con l’incremento della temperatura (8°C: = 42,6% vivi; 15°C: = 1,7% vivi), dimostrando l’esistenza di un effetto sinergico. Pur restando in attesa di maggiori informazioni sul ciclo vitale, si può formulare l’ipotesi che questa specie antartica possieda ampie potenzialità di sopravvivenza ad eventuali cambiamenti ambientali.
2013
- Integrative taxonomy allows the identification of synonymous species and the erection of a new genus of Echiniscidae (Tardigrada, Heterotardigrada)
[Articolo su rivista]
Filipe, Vicente; Paulo, Fontoura; Cesari, Michele; Rebecchi, Lorena; Guidetti, Roberto; Artur, Serrano; Bertolani, Roberto
abstract
The taxonomy of tardigrades is challenging as these animals demonstrate a limited number of useful morphological characters, therefore several species descriptions are supported by only minor differences. For example, Echiniscus oihonnae and Echiniscus multispinosus are separated exclusively by the absence or presence of dorsal spines at position Bd. Doubts were raised on the validity of these two species, which were often sampled together. Using an integrative approach, based on genetic and morphological investigations, we studied two new Portuguese populations, and compared these with archived collections. We have determined that the two species must be considered synonymous with Echiniscus oihonnae the senior synonym. Our study showed generally low genetic distances of cox1 gene (with a maximum of 4.1%), with specimens displaying both morphologies sharing the same haplotype, and revealed character Bd to be variable. Additionally, a more detailed morphological and phylogenetic study based on the 18S gene uncovered a new evolutionary line within the Echiniscidae, which justified the erection of Diploechiniscus gen. nov. The new genus is in a sister group relationship with Echiniscus and is, for the moment, composed of a single species.
2013
- Physiological and biochemical adaptive responses and defense mechanisms to withstand increasing ultraviolet radiation and temperatures in an Antarctic meiofauna organism.
[Abstract in Atti di Convegno]
Giovannini, Ilaria; Guidetti, Roberto; Altiero, Tiziana; Cesari, Michele; Montorfano, G.; Rizzo, A. M.; Bertolani, Roberto; Rebecchi, Lorena
abstract
Physiological and biochemical adaptive responses and defense mechanisms to withstand increasing ultraviolet radiation and temperatures in an Antarctic meiofauna organism.
2013
- Proceedings of the 12th International Symposium on tardigrada
[Curatela]
Rebecchi, Lorena; D., R: Nelson; Bertolani, Roberto; P., Fontoura
abstract
Proceedings of 12th International Symposium on Tardigrada. 23-26 July 2012 Vila Nova de Gaia Portugal
2013
- Tardigrades: multicellular organisms aboard the International Space Station (ISS)
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Altiero, Tiziana; Guidetti, Roberto; Montorfano, G.; Cesari, Michele; Bertolani, Roberto; Rizzo, A. M.
abstract
Tardigrades: multicellular organisms aboard the International Space Station
2013
- The impact of fire on terrestrial tardigrade biodiversity: a first case-study from Portugal
[Articolo su rivista]
Filipe, Vicente; Cesari, Michele; Artur, Serrano; Bertolani, Roberto
abstract
Currently, loss of habitat is the greatest threat to biodiversity, yet little is known about its effect on microscopic animal taxa, such as Tardigrada. One of the causes of habitat destruction is forest fire, both natural and anthropogenic. The latter is commonly used in agriculture to kill insect pests, as a soil preparation, or conservation to create habitat mosaics. In Portugal, 42% of fire frequency is anthropogenic. There is no consensus on the impact of fires on biodiversity, with studies pointing towards different conclusions. Different methods and target taxonomic study groups may partly explain this paradigm. This study is the first into possible effects of habitat destruction on tardigrade populations, in which we analysed the taxonomic and genetic variations of tardigrades from a fire affected location in a Portuguese natural park.. Sampling was performed over 10-year period, from 2000 to 2010. The location was affected by a small fire in 1998 and a big fire in 2003. A total of 11 species from nine separate genera was recorded, from which 19 cox1 haplotypes were identified. Our data suggest a negative effect of a forest fire on tardigrade populations. Taxonomic and genetic richness, as well as abundance show lower levels in the years after a fire, compared with the preceding years. Additionally, the population recovered visibly faster after the small fire than after the bigger one. This is consistent with larger fires destroying larger forest areas, leaving fewer animals at a farther distance available for re-colonisation. Most species found before the main fire are also found after it, indicating these tardigrades have a high recolonisation capability. However, only three of all recorded haplotypes were found both pre and post the main fire, which indicates genetic diversity loss as a direct consequence of fire. Therefore, we conclude that habitat destruction by means of forest fire has a detrimental effect on tardigrade biodiversity, and may have similar effects on other small animals.
2012
- A DNA barcoding approach in the study of tardigrades.
[Abstract in Atti di Convegno]
Cesari, Michele; Rebecchi, Lorena; Guidetti, Roberto; Giovannini, Ilaria; Mori, L.; Bertolani, Roberto
abstract
DNA barcoding is a technique proposed by Hebert and coworkers in 2003 and it aims to discriminate biological entities through analysis of a single gene barcode locus. The DNA barcoding system promised a better taxonomic resolution than that achieved through morphological studies, with a partial solution to the decline in taxonomic knowledge. Today DNA barcoding is a global enterprise, and the implementation of the idea has seen a rapid rise (more than 450 papers published to date on different organisms). Nonetheless, controversy still arises regarding barcoding and taxonomy. It is important to note that DNA barcoding does not focus on building a tree-of-life or on doing DNA taxonomy, even though sometimes it has been used for these purposes. DNA barcoding rather focuses on producing a universal molecular identification key based on strong taxonomic knowledge that should be included in the barcode reference library.
In Phylum Tardigrada, DNA barcoding represents a recent approach to species identification and for helping to solve taxonomic problems, especially considering the diminutive size of these animals and the paucity of morphological characters useful for taxonomy. In the framework of the MoDNA Project (Morphology and DNA), carried out by our research group in collaboration with several colleagues, we are combining the study of a fragment of the mitochondrial cytochrome c oxidase subunit I gene (cox1) with morphological data, in a wide sense, to form an integrative taxonomy of tardigrades.
Building of a database of reference sequences is of paramount importance for a correct application of DNA barcoding in tardigrades. Without verified reference sequences from voucher specimens that have been authenticated by qualified taxonomists, there is no reliable library for newly generated sequences with which to be compared. Methods and protocols for standardized results are focused on obtaining tight correspondence between molecular sequence and animal morphology, possibly both LM and SEM images (and egg shell morphology, when useful). This approach is particularly useful in describing new species, and important when applied on material collected in type localities.
Results using this approach are presented, focusing primarily on a number of species from the so-called “Macrobiotus hufelandi group”.
2012
- BIOKIS: a model payload for multidisciplinary experiments in microgravity.
[Articolo su rivista]
Vukich, M.; P. L., Ganga; D., Cavalieri; D., Rivero; S., Pollastri; S., Mugnai; S., Mancuso; S., Pastorelli; M., Lambreva; A., Antonacci; A., Margonelli; I., Bertalan; U., Johanningmeier; M. T., Giardi; G., Rea; M., Pugliese; M., Quarto; V., Roca; A., Zanin; O., Borla; Rebecchi, Lorena; Altiero, Tiziana; Guidetti, Roberto; Cesari, Michele; Marchioro, Trevor; Bertolani, Roberto; E., Pace; A., De Sio; M., Casarosa; L., Tozzetti; S., Branciamore; E., Gallori; M., Scarigella; M., Bruzzi; M., Bucciolini; C., Talamonti; A., Donati; V., Zolesi
abstract
In this paper we report about 1 the BIOKIS 2 payload: a multidisciplinary set of experiments and measurements in the fields of Biology and Dosimetry performed in microgravity. BIOKIS took advantage of the last STS-134 Endeavour mission and engineering state of the art in Space Life Science. The BIOKIS payload is compact, efficient, and capable to host experiments with different samples and science disciplines. Moreover, the time overlap of biological experiments and dosimetry measurements will produce more insightful information.
2012
- Comparative analyses of the cuticular and muscular structures of the buccal-pharyngeal apparatus of tardigrades
[Abstract in Atti di Convegno]
Guidetti, Roberto; Marchioro, Trevor; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena
abstract
In spite of the great importance of the tardigrade buccal pharyngeal apparatus in taxonomic and phylogenetic studies, it received little attention as regards its evolution and operating mechanism. To understand the relationships between form and function of the structures acting in the functioning of buccal-pharyngeal apparatus (i.e. cuticular structures, muscular fibers, pharynx), and to increase our knowledge on this apparatus, a comparative analyses using different investigation techniques was performed. The buccal-pharyngeal apparatuses of three species have been studied, Echiniscus trisetosus, Milnesium tardigradum e Paramacrobiotus richtersi, as representative of the two classes and of three orders of tardigrades. The cuticular structures of the buccal-pharyngeal apparatus have been analyzed form a morphological (light microscopy, scanning electron microscopy – SEM, and confocal laser scanner microscopy -CLSM) and chemical (energy dispersive X-ray spectroscopy) point of views. The musculature associated to the sclerified structures of the buccal-pharyngeal apparatus has been analyzed by CLSM to identify the muscular fibers and their relationships with the sclerified structures.
The differences in the general anatomy of the buccal-pharyngeal apparatus among the three species were high, even though homologous structures were recognizable. The higher differences among species were found in the organization of the muscular system responsible of the stylet movements. The detailed analyses of the buccal-pharyngeal apparatus allowed a new interpretation of the organization of the stylet systems, and to understand the muscular system related to the feeding.
The chemical analyses showed that the piercing stylets were formed by calcium, in form of CaCO3. Heterotardigrada were differentiated from Eutardigrada for the presence of high concentration CaCO3 encrustations in the buccal tube. Within Eutardigrada, Apochela differs from Parachela since they are characterized by the absence of CaCO3 in the buccal tube.
2012
- Comparative analysis and phylogenetic implications of tardigrade musculature architectures.
[Abstract in Atti di Convegno]
Marchioro, Trevor; Rebecchi, Lorena; Hansen, J. Gulberg; Bertolani, Roberto; Guidetti, Roberto
abstract
Most knowledge on tardigrade musculature architecture dates back to the end of XIX century, and the beginning of XX century. It has been only in the last five years that a great deal of new information on tardigrade musculature system has become available, mainly thanks to the use of rhodamine-phalloidin staining of F-actin in combination with three-dimensional microscopical techniques such as confocal laser scanning microscopy (CLSM). In spite of all these information, only few and fragmentary evolutionary considerations on tardigrade musculature system have been done. This is probably due to the relatively low number of analyzed taxa, and to the difficulty in the comparisons of data that often have been obtained with different degree of accuracy, and are presented using different terminologies.
In this study we increased the number of analyzed species, by studying CLSM the musculature architectures of 7 species representative of most tardigrade higher taxa: the heterotardigrades Batillipes bullacaudatus (Arthrotardigrada), and Echiniscus testudo (Echiniscoidea), and the eutardigrades Paramacrobiotus richtersi, Dactylobiotus parthenogeneticus (Parachela, Macrobiotoidea), Bertolanius volubilis (Parachela, Eohypsibioidea), Acutuncus antarcticus (Parachela, Hypsibioidea) and Milnesium tardigradum (Apochela, Milnesiidae). We were able to define all the muscular fibers associated with the body movement. The number of fibers and their organization changed among taxa, with heterotardigrades being the least complex. Muscular fibers have been schematically organized into three systems: dorsal, lateral, and ventral. The ventral system was the most conservative, showing a clear metameric pattern and only few differences among taxa, while the lateral system was the most derived and so precise homologies were not always well defined.
Using these new morphological information and literature data on Halobiotus crispae (Parachela, Isohypsibioidea), it was possible to analyse the phylogenetic signal of the musculature system. Two matrixes were constructed: a morphological matrix of 94 characters based on musculature data, and a matrix for a total evidence analysis combining the previous data with molecular data (18S, 28S). Both matrixes have been analyzed in Bayesian and parsimony frameworks. The phylogenetic trees, obtained by both analyses using both matrixes, differ only for the position of Eohypsibioidea. Heterotardigrade taxa were the sister group of all Eutardigrada, within this last class, Apochela and Parachela were sister taxa; among parachelan superfamilies the Isohypsibioidea was the most basal, the Macrobiotoidea the most derived, while the Eohypsibioidea changed position according to the analyses. Our data demonstrated that musculature architecture can be used for phylogenetic purposes, but it is only applicable at higher taxonomic levels. Indeed, the musculature of Paramacrobiotus and Dactylobiotus, although belonging to different families of Macrobiotoidea, showed the same muscular organization.
2012
- Diversified bet-hedging strategy in the desiccation tolerant tardigrade Paramacrobiotus richtersi
[Abstract in Atti di Convegno]
Altiero, Tiziana; Rossi, V.; Bertolani, Roberto; Rebecchi, Lorena
abstract
In variable environmental conditions a genotype may reduce the risk associated with reproduction by two main types of bet-hedging strategies: conservative and diversified bet-hedging. The former involves an avoidance of extremes to minimize fluctuations in a life-history trait that will assure an optimal mean for energetic constraints. The latter entails probabilistic risk spreading among individuals of the same genotype that express a range of diversified phenotypes to sample a range of different environments through time. Diversified bet-hedging is generally considered the most viable strategy for a long-term performance in a habitat varying in an unpredictable way. To date, only a few empirical studies provide evidence that bet-hedging occurs in nature.
The timing of many phenological events (e.g. egg hatching) results from a complex interplay among organism genotype, environmental factors and maternal effects (e.g. egg size). The relationship between egg size and development time is known and it is generally accepted that larger eggs take longer to develop than smaller ones. The production of eggs with variable size may represent a strategy by which a mother spreads the risk connected with life in a temporary habitat.
As regards tardigrades, they evolved a large variety of dormant stages that can be ascribed to diapause (encystment, resting eggs) and cryptobiosis (anhydrobiosis, cryobiosis, anoxibiosis). Therefore, their life-cycle can be generally divided into two very distinct stages: the active stage and the dormant stage, which are characterized by substantially different requirements and risks. During the active stage, tardigrades may exhibit high plasticity in life history traits (e.g. egg number, egg size and hatching time), as an adaptive measure to cope with risks linked to unpredictable habitat conditions.
Clonal lineages from an apomictic population of Paramacrobiotus richtersi (Eutardigrada, Macrobiotidae) may produce up to four kinds of eggs: subitaneous eggs, delayed-hatching eggs, abortive eggs and diapause resting eggs, the last ones require a stimulus to hatch (e.g. rehydration after a period of desiccation). The lack of genetic variation expected among clonal organisms make them ideal material for investigating diversified bet-hedging that is, by definition, life history trait variance expressed within genotypes, and maternal effects.
We compared the proportion of different kinds of eggs and analysed the correlation between egg size and hatching time within clonal eggs.
Our preliminary results provide possible empirical support of the occurrence of diversified bet-hedging strategy due to maternal effect in tardigrades living in stochastic environments.
2012
- Form and function of the feeding apparatus in Eutardigrada (Tardigrada)
[Articolo su rivista]
Guidetti, Roberto; Altiero, Tiziana; Marchioro, Trevor; L., Sarzi Amadè; A. M., Avdonina; Bertolani, Roberto; Rebecchi, Lorena
abstract
Tardigrade feeding apparatus is a complexstructure with considerable taxonomic significance that canbe schematically divided into four parts: buccal ring, buccaltube, stylet system, and pharynx. We analyzed the finemorphology and the tridimensional organization of thetardigrade buccal–pharyngeal apparatus in order to clarifythe relationships between form and function and to identifynew characters for systematic and phylogenetic studies. Weconducted a comparative analysis of the cuticular structuresof the buccal–pharyngeal apparatuses of twelve eutardigradespecies, integrating data obtained by SEM and LMobservations. Morphological diversity was observed andnew cuticular structures such as the stylet coat of the styletsystem were identified. The synthesis of the buccal–pharyngealapparatus during molting was also analyzedobtaining a clear developmental sequence of its resynthesis.These findings lead us to redefine the previous interpretationsof the functioning mechanisms of the buccal–pharyngealapparatus and provide a more specific relationship between tardigrade diet and the anatomy of their feedingapparatuses. In addition, the detection by energy-dispersiveX-ray spectroscopy of calcium in the stylets, buccal tube,and placoids of eutardigrade species (i.e., Milnesium tardigradum,Paramacrobiotus richtersi) indicates that CaCO3incrustations are not an exclusive feature of heterotardigradesand lead to suppose that this trait was present in theancestors of both classes.
2012
- L'approccio di DNA barcoding nello studio dei tardigradi
[Abstract in Atti di Convegno]
Bertolani, Roberto; Rebecchi, Lorena; Guidetti, Roberto; Altiero, Tiziana; Giovannini, Ilaria; Mori, L.; Cesari, Michele
abstract
Il DNA barcoding è stato proposto da Hebert e coll. nel 2003 con lo scopo di discriminare entità biologiche attraverso l’analisi di un singolo locus genico. Oggi il suo utilizzo appare in rapida ascesa (più di 450 lavori pubblicati riguardanti organismi anche molto differenti). Ciononostante, esistono ancora molte controversie sull’utilizzo di questo approccio in tassonomia. È importante sottolineare che solitamente il DNA barcoding non dovrebbe essere impiegato per la filogenesi, anche se a volte ciò è accaduto, ma piuttosto focalizzarsi sulla costruzione di una chiave di identificazione molecolare universale, basata però su consistenti informazioni tassonomiche che devono essere incluse nella barcode reference library.
Nel Phylum Tardigrada, il DNA barcoding rappresenta un approccio recente per l’identificazione delle specie e per la risoluzione di problemi tassonomici, anche alla luce delle ridotte dimensioni degli animali e della limitatezza dei caratteri morfologici disponibili. Da queste premesse è stato sviluppato il progetto MoDNA (Morfologia e DNA), combinando lo studio di un frammento del gene mitocondriale citocromo c ossidasi I (cox1) con dati morfologici anche a livello fine, allo scopo di sviluppare e validare l’integrative taxonomy sul modello tardigradi. L’indagine è stata condotta su gruppi di specie affini e criptiche in più famiglie di Eutardigrada.
La costruzione di un database di sequenze di riferimento è di importanza capitale per una corretta applicazione di questa metodica. Tuttavia, non è meno importante che queste sequenze siano strettamente correlate a specifici voucher specimens validati da esperti tassonomi. In mancanza di questo, il database di riferimento non può essere del tutto affidabile.
Per raggiungere questo importante obiettivo sono stati sviluppati metodi e protocolli per ottenere risultati standardizzati ed una stretta corrispondenza tra sequenza di DNA e morfologia, possibilmente con documentazione sia al microscopio ottico che elettronico a scansione. Un valore aggiunto è rappresentato dalla possibilità di utilizzo di materiale proveniente dal locus typicus di una specie già descritta e ancor più dall’utilizzo del DNA barcoding nella descrizione di nuove specie.
2012
- Morphology, DNA barcoding and phylogeny of Macrobiotus persimilis and Macrobiotus polonicus.
[Abstract in Atti di Convegno]
Bertolani, Roberto; Cesari, Michele; Lisi, O.; Rebecchi, Lorena; Giovannini, Ilaria; Pilato, G.
abstract
Macrobiotus polonicus and Macrobiotus persimilis are two species of the “Macrobiotus hufelandi group” which are distinguished one from the other for the presence in M. polonicus of one lateral gibbosity on each hind leg, the size of cuticular pores (smaller and less evident in M. polonicus), the buccal tube size (larger in M. persimilis) and the egg processes (larger terminal discs and with more evident indentation in M. polonicus). However, the two taxa share peculiar characteristics: similar values of the pt index relative to the insertion point of the stylet supports on the buccal tube, first macroplacoid clearly longer than the second and with a central constriction, lunules of the hind legs clearly larger than those of the first three pairs and with an indented margin, egg shell smooth or with faint dots but without a reticular design. Therefore, it could be hypothesized that they belong to a single peculiar group, namely the “Macrobiotus polonicus/persimilis group”.
In order to verify this hypothesis, a morphological and DNA barcoding analysis (cox1) was carried out on tardigrades attributable to these two taxa and coming from five different localities in Italy and France.
This study revealed differences, both morphological and molecular, between some populations apparently belonging to the same species, which in some cases turned out to be cryptic species. A phylogenetic analysis using rDNA 18S was performed in order to verify the relationships among the species of this group and more in general among those of the “M. hufelandi group”.
The DNA barcoding analysis revealed a high divergence, with very high values of genetic distance among some populations (more than 18%). In one case (Enna, Sicily) at least two different and very distinct entities are present together. The morphological and morphometrical investigation, also based on type material, confirms this variety, showing that at least four species related to M. polonicus and three related to M. persimilis should be distinct. In several cases the relationship between morphology and cox1 sequence has been ascertained.
The dendrogram computed on 18S showed that there are two different sequences pertaining to the “M. polonicus/persimilis group” clustered in a single evolutionary line inside the main M. hufelandi cluster.
2012
- Storia della vita ed evoluzione
[Capitolo/Saggio]
Bertolani, Roberto
abstract
Si tratta di un testo di Zoologia generale per studenti universitari
2012
- Systematic position of Macrobiotus glebkai within the “hufelandi group”, based on morphology and molecular analysis of a population from Ukraine
[Abstract in Atti di Convegno]
Kiosya, Y. e. O.; Bertolani, Roberto; Rebecchi, Lorena; Altiero, Tiziana; Cesari, Michele
abstract
The “Macrobiotus hufelandi group” is characterized by species which share some distinguishing animal and egg shell characters. In general, they have two rod-shaped macroplacoids and an evident microplacoid, eye spots, pores on the cuticle, medium sized claws, egg shell with inverted goblet-like processes, and spermatozoa with corkscrew-shaped head. We had the opportunity to analyse one species, Macrobiotus glebkai Biserov, 1990, found in Eastern Ukraine, which shows characters of the group in the animals, but a peculiar egg shell morphology.
We have carried out a phylogenetic analysis on the 18S nuclear gene in order to verify the systematic position of this species. This analysis has been followed by an integrated study on morphology by LM and SEM, sex ratio, karyology and DNA barcoding (mtDNA cox1).
The phylogenetic tree based on 18S sequences grouped M. glebkai with M. hufelandi and other related species with inverted goblet-like processes on the egg shell. This evidences that the egg shell morphology can sometimes be more variable than that of the animals. In depth morphological analysis allowed us to define details of both animals and eggs of M. glebkai, which showed the same characters as the Russian type material (that we also investigated). We verified that the population from Eastern Ukraine was composed by females and males and that the spermatozoon morphology is in line with that found in the various species of the “Macrobiotus hufelandi group”. The oocytes contain bivalents, but their number has to be specified, as oocytes of some specimens appeared to contain more than 6 bivalents (6 bivalents is the usual pattern for amphimictic species of the “M.hufelandi group”). The DNA barcoding has evidenced the presence of three haplotypes (Kimura 2-parameter distances: 0.2-0.3%) belonging to the same haplogroup, well differentiated (more than 20%) from M. hufelandi and the other considered species of the group.
2012
- Tardigrades on board of the STS-134 space flight
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Altiero, Tiziana; Rizzo, A. M.; Cesari, Michele; Montorfano, G.; Marchioro, Trevor; Bertolani, Roberto; Guidetti, Roberto
abstract
The joint ASI-AM DAMA mission supported a set of scientific experiments executed in short-duration microgravity on board the Space Shuttle docked to the International Space Station. BIOKIS payload (by Kayser Italia) took advantage of the last STS-134 Endeavour mission lasted 16 days. It hosted a multidisciplinary set of experiments in the field of biology and dosimetry. Among them, the TARDIKISS project investigated the responses of live desiccated tardigrades, multicellular heterotrophic organisms, under space stresses. In particular, specimens of Paramacrobiotus richtersi and Ramazzottius oberhaeuseri have been used. The experimental flight units were hosted into the Biokon, a standard transportable container. In addition, a Laboratory Control sample was maintained in Modena laboratory for the duration of the flight, while a post-flight Temperature Control sample was exposed to the temperature profile experienced by tardigrades during the mission.
For both species, the Flight animals did not show differences in survival with regard to Laboratory and Temperature control animals. Only in R. oberhaeuseri differences have been recorded between Flight and Temperature Control samples. Specimens of P. richtersi from Flight, Laboratory and Temperature control samples have been reared in lab. Flight females laid eggs with normal shape; several eggs have been able to hatch, and newborns exhibited, when adult, normal capability to reproduce. The comparative analysis of the antioxidant metabolism between Flight and Temperature control samples did not evidenced significantly differences between the two groups. These data confirm that tardigrades represent a useful animal tool for space research.
The authors thanks the Italian Space agency, Italian Air Force and Kayser Italia S.r.l.
2012
- Two tardigrade species on board of the STS-134 space flight
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Altiero, Tiziana; Rizzo, A. M.; Cesari, Michele; Montorfano, G.; Marchioro, Trevor; Bertolani, Roberto; Guidetti, Roberto
abstract
The TARDIKISS project (Tardigrades in Space) investigated the physiological and molecular effects of space stresses on alive desiccated tardigrades, as representative of multicellular organisms. It has been a part of the BIOKIS (Biokon in Space), a set of multidisciplinary experiments of DAMA (DArk MAtter) mission on board of STS-134 space flight, the last of the shuttle Endeavour, in the frame of a joint between ASI and Italian Air Force.
In TARDIKISS, experimentally desiccated (anhydrobiotic) specimens of Paramacrobiotus richtersi and Ramazzottius oberhaeuseri have been used. Both species have very good anhydrobiotic ability, but differ for several biological and ecological characters. The experiment units of TARDIKISS were hosted into the Biokon, a standard transportable container designed and manufactured by Kayser Italia. In May 2011, the Biokon containing the TARDIKISS experiment unit was integrated on Middeck Locker of ISS and had flown for 16 days at Low Earth Orbit.
Two sample sets were used as controls: the former (Laboratory Control) was maintained in Modena laboratory for the duration of the flight, and the latter one (Temperature Control) was a post-flight control in which samples were exposed to the temperature profile experienced by tardigrades the days immediately before, during, and just after the flight mission.
For both species, the flight animals did not show differences in survival with regards of Laboratory control and Temperature control animals. Only in R. oberhaeuseri differences have been recorded between Flight and Temperature Control samples. Live specimens of P. richtersi from Flight samples, Laboratory control and Temperature control samples have been reared in lab. Flight females laid eggs with normal shape; several eggs have been able to hatch, and newborns exhibited normal morphology, behaviour and capability to reproduce. Moreover, a comparative analyses of the antioxidant metabolism between Flight samples and Temperature control samples has been done. No differences have been evidenced between the two groups, with the exception of the reductase activity: significant differences in reductase activity between Flight and Temperature control were evidenced (p<0.05) in R. oberhaeuseri. These first results lead us to deduce that during the DAMA mission, microgravity and cosmic radiations did not significantly affect survival of flown tardigrades, confirming that tardigrades represent a useful animal tool for space research.
2011
- An example of problems associated with DNA barcoding in tardigrades: a novel method for obtaining voucher specimens
[Articolo su rivista]
Cesari, Michele; Giovannini, Ilaria; Bertolani, Roberto; Rebecchi, Lorena
abstract
We have in recent papers revealed that an integrative taxonomy approach helps to solve taxonomic problems in tardigrades. However, whole tardigrades are required for DNA work, which leaves no hologenophore voucher specimens with adult morphology. Using a novel methodology for the Tardigrada, we introduce the practice of collecting high quality maximum magnification light microscopy images of recently thawed animals to act as hologenophore voucher specimens of animals later used for DNA barcode sequencing. Within the framework of a DNA barcoding project on tardigrades, we collected a moss sample from the type locality of Macrobiotus terminalis Bertolani & Rebecchi, 1993 (Castelsantangelo, Central Apennines, Italy), a species of the “Macrobiotus hufelandi group”. Within the moss sample we found several animals and eggs with a morphology that corresponded to the original description of M. terminalis, while others were attributable to Macrobiotus macrocalix Bertolani & Rebecchi, 1993. In this study, molecular (cox1 mtDNA) analyses demonstrated no intraspecific variability in M. terminalis from the type locality but very large interspecific differences when compared with M. macrocalix and GenBank data for other species within the M. “hufelandi group”. There was also a large difference between our M. terminalis sequences and the GenBank data of a specimen attributed to the same species. The GenBank sequence originated from a population in the Northern Apennines, whose morphology appeared to be like that of the specimens of the locus typicus. This confirmed the importance in utilising material from the type locality for linking molecular data to the species’ morphological characters. Our paper underlines the importance of an integrative taxonomy in species diagnoses and demonstrates a scenario where morphological observations alone are not always sufficient. Lastly, this work adds reliable information to the sequence reference library that provides a useful building block for further studies on similar and related tardigrade taxa.
2011
- Changes in scientific approaches as seen through 35 years of tardigrade symposia.
[Articolo su rivista]
Bertolani, Roberto; D. R., Nelson
abstract
The story of the Tardigrada Symposia began 35 years ago in Pallanza, Italy. It was an idea of Professor Livia Tonolli, who wanted to honour Professor Giuseppe Ramazzotti, at that time the authority in that scientific field and her friend. Considering that tardigrades are a neglected group of metazoans (still to date), this particular event could be finished with that occasion, but it has not been so. With some gaps, the meetings have been proceeded till now, promoting scientific exchange among the researchers and improving the research quality. Following these 35 years and the topics of the symposia, we can understand the changing in the scientific approach. Taxonomy and faunal studies were the predominant topics of the first symposium, but also ultrastructural morphology, ecology, physiology, cytotaxonomy and reproductive biology were represented. Furthermore, the studies by SEM moved their first steps in that occasion. Faunal and taxonomic studies represented often the main topic during the years, but also other kinds of researches involving phylogeny, physiology, ultrastructure of organs and cells always accompanied it. From these points of view, often tardigrades were compared with other animal groups, giving a wider sense to the research. Molecular aspects were already considered in the third symposium (1980, Tennessee), but reconsidered only in the symposium in Cambridge (1994) and developed from the symposium in Denmark (2000). The last symposia showed an increased number of participants and scientific contributions. In line with the increasingly international nature of publications, the quality of the proceedings has also increased, always using in the last 10 years qualified international journals with peer review and impact factor, as now required by young scientists to further their careers.
2011
- DNA barcoding and integrative taxonomy of Macrobiotus hufelandi C.A.S. Schultze 1834, the first tardigrade species to be described, and some related species.
[Articolo su rivista]
Bertolani, Roberto; Rebecchi, Lorena; Giovannini, Ilaria; Cesari, Michele
abstract
Within the framework of a DNA barcoding project on tardigrade species, a study was carried out on Macrobiotus hufelandi C.A.S. Schultze 1834, the first formally described tardigrade species. We used samples collected from the type locality and additional material from other European sites containing species of the “M. hufelandi group”. The study was performed by integrating morphological, karyological and molecular (mt-DNA cox1) information and comparing these data with morphological data from the type material. Several species from this group were found in the type locality of M. hufelandi (near Freiburg, Black Forest, Germany) and these were all barcoded. One was M. hufelandi, the other two were: Macrobiotus sandrae Bertolani & Rebecchi 1993 (originally described from the same locality), and Macrobiotus vladimiri Bertolani, Biserov, Rebecchi & Cesari in press (type locality Andalo, Italy), all with interspecific genetic distances of more than 19%. A fourth cryptic species, which had the same morphology as M. hufelandi but a genetic distance of 6.7%, was not described as a new taxon but named M. cf. hufelandi sp.1 for this study. Macrobiotus sandrae and M. vladimiri were also present (and barcoded) in Italy (Alps). Additional individuals (animals and eggs) were also found, and barcoded, in Italy (Apennines) and Switzerland that belonged to the haplogroup Macrobiotus cf. hufelandi sp. 1. These data together with other recent studies on tardigrade DNA barcoding represent a starting point for further studies on tardigrade biogeography, phylogeography and diversity.
2011
- DNA barcoding e strategie riproduttive nel genere Ramazzottius (Tardigrada, Eutardigrada)
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Bigi, Mila; Bertolani, Roberto; Altiero, Tiziana; Cesari, Michele
abstract
Nell’ambito del progetto MoDNA (morfologia e DNA) è stato utilizzato l’approccio del DNA barcoding, associato a comparazioni morfologiche e cariologiche. E’ stata valutata la variabilità inter- ed intraspecifica nel genere Ramazzottius, caratterizzato dalla presenza di specie criptiche e da diverse modalità riproduttive e talvolta diverso grado di ploidia.
Mediante approccio morfologico (LM, SEM) e molecolare (mtDNA cox1) sono stati analizzati esemplari di Ramazzottius provenienti da 15 località europee. Per correlare morfologia e sequenze sono stati allestiti voucher specimens, compresi gusci di uova (molto importanti per la diagnosi specifica) dalle quali sono sgusciati neonati utilizzati per l’analisi molecolare.
Tre campioni contengono rispettivamente Ramazzottius varieornatus, Ramazzottius tribulosus ed una nuova specie di Ramazzottius, distinguibili sia su base morfologica che molecolare. Negli altri campioni gli esemplari (animali e uova) sono tutti morfologicamente attribuibili a Ramazzottius oberhaeuseri, ma si distinguono tra loro per sex ratio, ploidia e per notevoli differenze molecolari.
I dati evidenziano la validità dell’approccio integrato nello studio della diversità nei tardigradi e dell’utilizzo del DNA barcoding. Nel genere Ramazzottius, ed in particolare nell’ambito della morfospecie R. oberhaeuseri, è confermata la presenza di specie criptiche, alcune delle quali con ampia diffusione e con strategie riproduttive diverse.
2011
- Filogenesi e integrative taxonomy nei Macrobiotus del “gruppo hufelandi” (Tardigrada, Eutardigrada)
[Abstract in Atti di Convegno]
Cesari, Michele; Rebecchi, Lorena; Giovannini, Ilaria; Pilato, G.; Lisi, O.; Vicente, F.; Kiosya, Y.; Bertolani, Roberto
abstract
Analiisi della filogenesi dei Macriobiotus del gruppo hufelandi medainte un approccio integrativo
2011
- Onicofori e Tardigradi
[Capitolo/Saggio]
Bertolani, Roberto
abstract
E' un trattato di zoologia sistematica per studenti universitari
2011
- Phylum Tardigrada Doyère, 1840
[Articolo su rivista]
Guidetti, Roberto; Bertolani, Roberto
abstract
Updated taxonomy of the phylum Tardigrada
2011
- Resistance of the anhydrobiotic eutardigrade Paramacrobiotus richtersi to space flight (LIFE–TARSE mission on FOTON-M3). ,
[Articolo su rivista]
Rebecchi, Lorena; Altiero, Tiziana; Cesari, Michele; Bertolani, Roberto; A. M., Rizzo; P., Corsetto; Guidetti, Roberto
abstract
The project “TArdigrade Resistance to Space Effects (TARSE)” analyzed the effects of space environment stresses on the eutardigrade Paramacrobiotus richtersi allowing, for the first time, a comparison between hydrated and desiccated animals. TARSE experiments were part of the mission LIFE on FOTON-M3 that flew at an altitude between 250-290 km for 12 days in September 2007. In this paper, data on survival rate, Hsps expression (70 kDa and 90 kDa) and genomic DNA integrity (double strand breaks) of flown desiccated animals, and from specimens in ground control experiments are presented. For the flown experiments, microcosms of dry leaf litter collected in the field containing naturally desiccated specimens and square papers containing specimens desiccated under controlled conditions were used. After the space flight, desiccated animals had high survival rates (from 79% to 95%) showing a similar survival rate to that observed in ground controls. No visible damages to double strand genomic DNA were observed in all desiccated samples, while spaceflight induced the Hsps expression (Hsp70 and Hsp90) compared to ground controls. These data combined with earlier published results on hydrated specimens of P. richtersi indicate that tardigrades have the ability to tolerate for a short period of time several extreme stresses typical of the extraterrestrial environment.
2011
- Strutture cuticolari e muscolatura dell’apparato bucco-faringeo dei tardigradi
[Abstract in Atti di Convegno]
Guidetti, Roberto; Marchioro, Trevor; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena
abstract
L’apparato bucco-faringeo dei tardigradi è composto da parti cuticolari sclerificate (compresi due stiletti perforanti ritenuti una delle apomorfie del phylum) e muscolatura. Con questo studio si è voluto sia comprendere al meglio il meccanismo di funzionamento di questo apparato che individuare nuovi caratteri per gli studi di tassonomia e filogenesi.
L’apparato bucco-faringeo di Echniscus trisetosus, Milnesium tardigradum e Paramacrobiotus richtersi (appartenenti a due classi e tre ordini del phylum) è stato studiato morfologicamente (microscopia ottica, microscopia elettronica a scansione) e chimicamente (spettroscopia a raggi X). E’ stata inoltre analizzata l’anatomia della muscolatura associata all’apparato mediante microscopia confocale a scansione laser.
Nelle tre specie le differenze nell’anatomia dell’apparato bucco-faringeo risultano notevoli , così come quelle relative all’organizzazione dei fasci muscolari ad esso associati. L’analisi chimica ha rivelato che gli stiletti sono costituiti da CaCO3 e che le due classi di tardigradi si differenziano per la presenza/assenza di CaCO3 sul tubo boccale.
L’analisi dettagliata delle strutture cuticolari dell’apparato bucco-faringeo e della sua muscolatura ha consentito una nuova interpretazione dell’organizzazione e del funzionamento del sistema di protrazione e retrazione degli stiletti. Sebbene nelle strutture sclerificate dei tre ordini siano riconoscibili diverse omologie, queste sono più difficilmente riscontrabili nella muscolatura.
2011
- Survival of freezing by hydrated tardigrades inhabiting terrestrial and freshwater habitats
[Articolo su rivista]
Guidetti, Roberto; Altiero, Tiziana; Bertolani, Roberto; Grazioso, Pasqualina; Rebecchi, Lorena
abstract
The seasonality and unpredictability of environmental conditions at high altitudes and latitudes govern the life cycle patterns of organisms giving rise to stresses that cause dead or development of specific adaptations. Ice formation is a major variable affecting survival of both freshwater fauna and fauna inhabiting lichens, mosses and leaf litter. Tardigrades occupy a wide range of niches in marine, freshwater and terrestrial environments. The highest number of species is found in terrestrial habitats thanks to their ability to enter anhydrobiosis and cryobiosis. The cryobiotic ability of tardigrade species from polar regions is well known. Consequently, we focused our research on the ability to survive freezing in active hydrated state using seven tardigrade species differing in phylogenetic position and collected at various altitudes and from different habitats in a temperate area. Replicates were cooled at different cooling rates (from 0.31 °C min-1 to 3.26 °C min-1). Even though the final survival and the time required by animals to recover active life were both inversely related to the cooling rates, highly significant interspecific differences were found. Species survival ability ranges from excellent to none. Species living in xeric habitats withstand freezing better than those living in hygrophilous habitats, while true limnic species do not exhibit cryobiotic capabilities. The ability to withstand freezing seems linked to the anhydrobiotic ability. The difference in cryptobiotic performance among tardigrade species seems more influenced by selective pressures linked to local adaptation to habitat characteristics than by phylogenetic relationships.
2011
- TARDIKISS: tardigrades in the mission STS-134, the last of the shuttle Endeavour.
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Altiero, Tiziana; Cesari, Michele; Marchioro, Trevor; Rizzo, A. M.; Ganga, P. L.; Vukich, M.; Donati, A.; Zolesi, V.; Bertolani, Roberto; Guidetti, Roberto
abstract
The TARDIKISS project (Tardigrades in Space) investigates the physiological and molecular effects of space stresses on alive desiccated multicellular organisms, the tardigrades. It is a part of the BIOKIS (Biokon in Space), a set of multidisciplinary experiments of DAMA (DArk MAtter) mission on board of STS-134 space flight, the last of the shuttle Endeavour, in the frame of a joint between ASI and Italian Air Force.
In TARDIKISS, experimentally desiccated (anhydrobiotic) specimens of Paramacrobiotus richtersi and Ramazzottius oberhaeuseri have been used. Both species have very good anhydrobiotic ability, but differ for several biological and ecological characters. Paramacrobiotus richtersi is carnivorous, soil-dwelling and white in colour, while R. oberhaeuseri is lichen-dwelling, herbivorous, and characterized by a brown/red pigmentation. The experiment units of TARDIKISS were hosted into the Biokon, a standard transportable container designed and manufactured by Kayser Italia. In May 2011, the Biokon containing the TARDIKISS experiment unit was integrated on Middeck Locker of ISS and had flown for 16 days. As control, ground experiments replicating the temperature profile recorded within the Biokon during the flight are currently running.
To this day, we have completed the analysis on tardigrade survival after the space flight and obtained preliminary data on life cycle parameters. Both tardigrade species showed a very high survival (98.33% for P. richtersi and 90.0% for R. oberhaeuseri) and no significant differences were scored between flight or Earth tardigrades. After the flight, specimens of P. richtersi were reared in lab. Females laid eggs with normal shape; several eggs hatched with a short hatching time and newborns exhibited normal morphology and behaviour. In the next step, genomic DNA quality and oxidative metabolism of flown tardigrades vs ground control tardigrades will be analysed.
2011
- Taxonomy and biogeography of tardigrades using an integrated approach: new results on species of the Macrobiotus hufelandi group
[Articolo su rivista]
Bertolani, Roberto; V. I., Biserov; Rebecchi, Lorena; Cesari, Michele
abstract
This study reconsiders a tardigrade population previously studied and tentatively attributed to Macrobiotus cf. terminalis by Bertolani, Rebecchi (1993) with a new approach by joining molecular and indispensible traditional methods, light microscopy, and scanning electron microscopy. Differences in adult animals and, above all, egg shell morphology, and the peculiar cox1 sequence indicate that this population clearly belongs to a new species, M. vladimiri sp. n., which is here described. The results provide an example of how modern taxonomic and biogeographical research can be carried out on this animal phylum and in general on the animals belonging to the so-called meiofauna,in which morphological characters are often very few. This is the first tardigrade species to be described and barcoded contemporarily.
2010
- A model study for tardigrade identification
[Relazione in Atti di Convegno]
Bertolani, Roberto; Rebecchi, Lorena; Cesari, Michele
abstract
Using tardigrades from a single moss sample as a case study,we propose a new method for tardigrade species identification, which is often problematic, due to the low number of orphological characters. Identification at generic level was carried out on adults, while morphological analyses were performed on animals (LM) and eggs (LM and SEM), including hologenophores, vouchers used also for molecular analysis of COI mtDNA. This multi-approach method revealed the presence of three species of the“Macrobiotus hufelandi group” instead of the two species identified in a previous study. The validity of the method is shown, indicating that it could be applied to studies of problematic meiofauna taxa.
2010
- Hatching phenology and resting eggs in tardigrades
[Articolo su rivista]
Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena
abstract
Little is known about egg dormancy in tardigrades, except for their ability to survive desiccated for a long time. Our previous analyses of life history traits of a reared strain of the leaf litter-dwelling eutardigrade Paramacrobiotus richtersi revealed variation in hatching phenology, suggesting the presence of diapause (resting) eggs in tardigrades. To study adaptive strategies in an unpredictable environment subject to stochastic variability, such as that colonized by tardigrades, we have analysed the hatching phenology of an apomictic triploid cytotype of P. richtersi. The first lab oviposition of mature females collected in the field in the spring and fall as well as cohorts of eggs laid by females born in the laboratory were used. The eggs of all samples, maintained at the same constant experimental conditions, had a high hatching percentage (from 75 to 93%) but high variability occurred in hatching time. Four patterns were identified. First, subitaneous eggs hatched within 30 - 40 days from oviposition. Second, delayed-hatching eggs hatched gradually over 41 – 62 days. Some eggs did not hatch within 90 days from oviposition when water was maintained in the culture. Within this group, 13% of eggs (diapause resting eggs; third category) do not hatch until they are subjected to desiccation followed by rehydration, while 87% never complete their development (abortive eggs; fourth category). The four categories of eggs had no morphological differences. The high variability in the hatching time of tardigrade eggs might be considered a form of bet-hedging.
2010
- I Tardigradi, questi sconosciuti … e questi fenomeni.
[Articolo su rivista]
Altiero, Tiziana; Bertolani, Roberto
abstract
Vengono descritte le caratteristiche morfologiche e biologiche di questo gruppo di microinvertebrati, valutando le sue relazioni con gli Artropodi ed approfondendo in particolare le capacità di resistenza agli stress degli ambienti estremi. Vengono infine prese in considerazione le potenzialità di questi animali nella ricerca applicata.
2010
- Thulinius saltursus comb. nov.: a new systematic position for Isohypsibius saltursus Schuster, Toftner & Grigarick, 1978 (Eutardigrada: Hypsibiidae)and a key for the genus Thulinius
[Articolo su rivista]
Ł., Kaczmarek; Bertolani, Roberto; M., Nędzyńska Stygar
abstract
Based on the type material Thulinius saltursus comb. nov., is redescribed. T. saltursus is very similar to other members of the genus Thulinius, but it differs from the most similar species mainly by morphometric characters of the buccal tube, claws and the presence of lunules only on the external claws. In this paper we also provide a key for all Thulinius species known to date and make some remarks on their distribution.
2009
- DNA barcoding in Tardigrada: the first case study on
Macrobiotus macrocalix Bertolani & Rebecchi 1993
(Eutardigrada, Macrobiotidae)
[Articolo su rivista]
Cesari, Michele; Bertolani, Roberto; Rebecchi, Lorena; Guidetti, Roberto
abstract
Morphological and molecular studies on a tardigrade species have been carried out to verify the possibility of using a DNA barcoding approach for species identification in this phylum. Macrobiotus macrocalix Bertolani & Rebecchi, 1993 was chosen as the test species since it belongs to a group of species in which the taxonomy is quite problematic. Animals and eggs belonging to three Italian and one Swedish populations have been investigated. Both morphological and molecular analyses show that all the populations belong to the same species. The low genetic distances recorded among the studied populations (0.3-1.0%) and the high genetic distance (15.9-16.3%) between these populations and a very closely related species confirm the possibility of identifying a specimen of this species by its COI sequence. Data from other authors support our results indicating that DNA barcoding can be applied to tardigrades. With our protocols, we have obtained voucher specimens that enable us to show a correspondence between morphology and molecular data.
2009
- New molecular data for tardigrade phylogeny, with the erection of Paramacrobiotus gen. nov.
[Articolo su rivista]
Guidetti, Roberto; R. O., Schill; Bertolani, Roberto; T., Dandekar; M., Wolf
abstract
Up to few years ago, the phylogenies of tardigrade taxa have been investigated using morphological data, but relationships within and between many taxa are still unresolved. Our aim has been to verify those relationships adding molecular analysis to morphological analysis, using nearly complete 18S ribosomal DNA gene sequences (five new) of 19 species, as well as cytochrome oxidase subunit 1 (COI) mitochondrial DNA gene sequences (15 new) from 20 species, from a total of seven families. The 18S rDNA tree was calculated by minimum evolution, maximum parsimony (MP) and maximum likelihood (ML) analyses. DNA sequences coding for COI were translated to amino acid sequences and a tree was also calculated by neighbour-joining, MP and ML analyses. For both trees (18S rDNA and COI) posterior probabilities were calculated by MrBayes. Prominent findings are as follows: the molecular data on Echiniscidae (Heterotardigrada) are in line with the phylogenetic relationships identifiable by morphological analysis. Among Eutardigrada, orders Apochela and Parachela are confirmed as sister groups. Ramazzottius (Hypsibiidae) results more related to Macrobiotidae than to the genera here considered of Hypsibiidae. Macrobiotidae and Macrobiotus result not monophyletic and confirm morphological data on the presence of at least two large groups within Macrobiotus. Using 18S rDNA and COI mtDNA genes, a new phylogenetic line has been identified within Macrobiotus, corresponding to the richtersi-areolatus group. Moreover, cryptic species have been identified within the Macrobiotus richtersi group and within Richtersius. Some evolutionary lines of tardigrades are confirmed, but others suggest taxonomic revision. In particular, the new genus Paramacrobiotus gen. n. has been identified, corresponding to the phylogenetic line represented by the richtersi-areolatus group.
2009
- Stress response of a boreo-alpine species of tardigrade, Borealibius zetlandicus (Eutardigrada, Hypsibiidae)
[Articolo su rivista]
Rebecchi, Lorena; D., Boschini; Cesari, Michele; V., Lencioni; Bertolani, Roberto; Guidetti, Roberto
abstract
Invertebrates living in extreme environments as well as those living under unpredictable habitat conditions must be able to survive severe environmental stresses bound to their habitats. Tardigrades represent a good animal model to analyze responses evolved by organisms to overcome extreme environmental stresses or to colonize extreme environments because they respond to desiccation or freezing in their habitats by entering cryptobiosis. The responses to environmental stresses have been evaluated almost exclusively in terrestrial tardigrades, while very little is known about the ability of limnic species to tolerate those stresses. This study evaluates the responses of the limnic boreo-alpine species Borealibius zetlandicus, under lab conditions, to stresses imposed by desiccation and temperature variation (freezing and heating). Our results indicate that active specimens are able to freeze, confirming the cryobiotic ability of this species. There is a negative correlation between survival and cooling rates. In contrast, no specimens of B. zetlandicus are able to survive desiccation. With regard to thermal tolerance, the animals show a high ability to resist heat-shock (LT50 = 33.0 0.5°C) for a short time. This wide tolerance to different environmental parameters could be the reason for the wide distribution of the species. Due to the disjunct distribution of the species and to the presence of cryptic tardigrade species that could have different ecological and physiological responses, we decided to characterize the population studied from a molecular point of view by investigating its COI mtDNA sequences.
2009
- Tardigrada (Water Bears)
[Capitolo/Saggio]
Bertolani, Roberto; Altiero, Tiziana; D. R., Nelson
abstract
Encyclopedia of Inland Waters is a new 3-volume reference work, pulling together all the key information in one source from the leading publisher in the field. Inland aquatic habitats occur worldwide at all scales from marshes, swamps and temporary puddles, to ponds, lakes and inland seas and from streams and creeks to rolling rivers. Vital for biological diversity and ecosystem function and as resources for human life, commerce and leisure, inland waters are a vital component of life on Earth. The Encyclopedia of Inland Waters describes and explains all the basic features of the subject, from water chemistry and physics, to the biology of aquatic creatures and the complex function and balance of aquatic ecosystems of varying size and complexity. In the chapter here reported, tardigrades are considered in their various aspects: morphology and anatomy, classification, phylogeny and evolution, reproduction and development, ecology, zoogeography, methods. The chapter is illustrated with many original figures.
2009
- Tardigrade resistance to space effects: first results of the experiment of LIFE – TARSE mission on FOTON-M3 (September 2007)
[Articolo su rivista]
Rebecchi, Lorena; Altiero, Tiziana; Guidetti, Roberto; Cesari, Michele; Bertolani, Roberto; M., Negroni; M. A., Rizzo
abstract
The TARSE (TArdigrade Resistance to Space Effects) project, part of the mission LIFE on FOTON-M3, analyzed the effects of the space environment on desiccated and active tardigrades. Four experiments were conducted in which the eutardigrade Macrobiotus richtersi was used as a model species. Desiccated (in leaf litter or on paper) and hydrated tardigrades (fed or starved) were flown on FOTON-M3 for 12 days in September 2007, which, for the first time, allowed for a comparison of the effects of the space environment on desiccated and on active animals. In this paper, we report the experimental design of the TARSE project and data on tardigrade survival. In addition, data on survival, genomic DNA integrity, Hsp70 and Hsp90 expressions, antioxidant enzyme contents and activities, and life history traits were compared between hydrated starved tardigrades flown in space and those maintained on Earth as a control. Microgravity and radiation had no effect on survival or DNA integrity of active tardigrades. Hsp expressions between the animals in space and the control animals on Earth were similar. Space flight induced an increase of glutathione content and its related enzymatic activities. Catalase and SOD decreased with space flight, and thiobarbituric acid reactive substances did not change. During the flight mission, tardigrades moulted and females laid eggs. Several eggs hatched and the newborns exhibited normal morphology and behavior.
2008
- A new discovery of Novechiniscus armadilloides (Schuster, 1975) (Tardigrada, Echiniscidae) from Utah, USA with considerations on non-marine Heterotardigrada phylogeny and biogeography.
[Articolo su rivista]
Rebecchi, Lorena; Altiero, Tiziana; E., Jacobsen; Bertolani, Roberto; R. M., Kristensen
abstract
The discovery of a new population of the non-marine heterotardigrade Novechiniscus armadilloides from Utah, USA, allowed us to re-analyze the species by means of scanning electron microscopy and differential interference contrast microscopy. This analysis confirmed the presence of bar-shaped, unpaired segmental plates and of a long filament E, other than the filament A always present in the class Heterotardigrada. It also provided additional information on characters not explicitly cited in the previous descriptions of this monotypic genus, such as details of the head cirri and clavae, details of the buccal tube and of the pharyngeal bulb, sculpture of the dorso-lateral and leg plates, details of the claws. The population is bisexual, but no secondary sexual dimorphism was observed. The male and female gonopore were described. New characters such as red eyes and red body color were used in analyzing the phylogeny of the family Echiniscidae. The phylogeny and biogeography of non-marine heterotardigrades provide intriguing questions for further research.
2008
- Cryptic Species in Macrobiotus (Tardigrada): A Morphological and Molecular Approach
[Abstract in Atti di Convegno]
Guidetti, Roberto; Bertolani, Roberto; Rebecchi, Lorena; Cesari, Michele
abstract
In the last years, morphological analysis of Tardigrada has been carried out even more in depth, leading to recognise many new species, thus reconsidering the concept of intraspecific variability. In addition, molecular approach has very recently identified a more complex scenario within some taxa, supposing or evidencing the presence of cryptic species. Our previous studies already identified a complex situation bound to karyology and reproductive biology within single morphospecies. For these reasons we have reconsidered populations belonging to the morphospecies Macrobiotus richtersi and to Macrobiotus “hufelandi group” analysing their morphology and mtDNA COI (cytochrome oxidase I) gene sequences. The presence of both diploid amphimictic and triploid apomictic populations has been confirmed in both taxa. In M. richtersi all animals are very similar, while limited differences have been evidenced in the egg shell ornamentations of some populations. DNA sequences have shown that populations with different reproductive modes (and ploidy degree) have always decidedly different haplotypes. Within parthenogens equal or very similar haplotypes are retrieved, while within amphimictics both equal and different haplotypes are found. In M. “hufelandi group” molecular analysis confirms the morphological diagnosis of 3 populations of Macrobiotus macrocalix, while it evidences differences between 2 populations attributed in references to Macrobiotus terminalis and M. cf. terminalis. A general conclusion is that in tardigrades it is important to integrate morphological and molecular analyses. In fact, in some instances the morphological approach is adequate to recognize the species, but sometimes the molecular approach is indispensable to identify cryptic species.
2008
- Designation of Pseudobiotus kathmanae Nelson, Marley & Bertolani, 1999 as the type species for the genus Pseudobiotus Nelson, 1980 (Tardigrada)
[Articolo su rivista]
N. J., Marley; Bertolani, Roberto; D. R., Nelson
abstract
The contents of the application to the International Commission of Zoological Nomenclature, case 3017, are presentedwith an explanation of how its publication fell between the third and fourth editions of the Code. In so doing, the genusPseudobiotus Nelson, 1980 (In: Schuster, Nelson, Grigarick & Christenberry, 1980) was left without a type species,which is hereby designated under article 70 of the fourth edition of the code
2008
- Diapause in tardigrades: a study of factors involved in encystment
[Articolo su rivista]
Guidetti, Roberto; D., Boschini; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena
abstract
Stressful environmental conditions limit survival, growth, and reproduction, or these conditions induce resting stages indicated as dormancy. Tardigrades represent one of the few animal phyla able to perform both forms of dormancy: quiescence and diapause. Different forms of cryptobiosis (quiescence) are widespread and studied, while little attention has been devoted to adaptive meaning of the encystment (diapause). Our goal was to determine environmental factors and token stimuli involved in the encystment process of tardigrades. The eutardigrade, Amphibolus volubilis, a species able to produce two types of cysts (type 1 and type 2), has been considered. Laboratory experiments and long-term study on cyst dynamics of a natural population were conducted. Laboratory experiments demonstrate that active tardigrades collected in April produced mainly type 2 cysts, whereas animals collected in November produced mainly type 1 cysts, indicating that the different responses are functions of the physiological state at the time they were collected. Dynamics of the two types of cyst show opposite seasonal trends: type 2 cysts are present only during the warm season and type 1 cysts, present during the cold season. Temperature represents the environmental factor involved in induction, maintenance, and termination of the cyst. We also evidenced that A. volubilis is able to perform both diapause and cryptobiosis, even overlapping the two phenomena. The induction phase of tardigrade encystment can be compared to the induction phase of insect diapause, also indicating an involvement of endogenous factors in tardigrade encystment. As in insect diapause, tardigrade encystment can be considered a diapausing state controlled by exogenous and endogenous stimuli.
2008
- Hsp levels and DNA integrity in anhydrobiotic tardigrades
[Abstract in Atti di Convegno]
Guidetti, Roberto; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena
abstract
Dehydrating cells can lead to massive damage in molecular organization, often resulting in cell death and, consequently, death of the organism. In anhydrobionts, several bioprotectants, e.g. sugars and stress proteins, play a role in avoiding these damages. In tardigrades (micrometazoans able to perform anhydrobiosis in any stage of their life cycle), bioprotectants are certainly involved, but their nature and role is only understood in part. We evaluated the Hsp70 and Hsp90 levels in hydrated and desiccated animals of two eutardigrade species: Macrobiotus richtersi and Amphibolus volubilis. For both species, we found no significant differences in the level of both Hsps between hydrated and anhydrobiotic specimens.Also, DNA can be damaged by dehydration. In several unicellular organisms, even though characterized by desiccation tolerance, dramatic DNA damages can occur during desiccation or in the dry state that follows. It has been hypothesized that DNA damages could also occur in anhydrobiotic tardigrades. To verify this hypothesis, we evaluated tardigrade survival and DNA desiccation-induced double (DSBs) and single (SSBs) strand breaks in specimens of M. richtersi naturally dried within leaf litter as well as experimentally desiccated in our lab under controlled conditions. Dry specimens were also exposed to thermal stress (37°C) at different values of air humidity (RH). An inverse relationship between M. richtersi survival and RH levels was found. Moreover, tardigrades dried within leaf litter, when re-hydrated had a faster recovery of active movement than those dehydrated on paper. No visible DNA DSBs were observed, but preliminary data on SSBs seems to bring different results, which need to be confirmed.
2008
- Primo esempio di DNA barcoding nei tardigradi: un approccio morfologico e molecolare.
[Abstract in Atti di Convegno]
Guidetti, Roberto; Bertolani, Roberto; Rebecchi, Lorena; Cesari, Michele
abstract
La tassonomia dei tardigradi è attualmente basata sull’analisi di caratteri morfologici. In questi ultimi anni lo studio di questi caratteri è stato notevolmente approfondito, portando ad un notevole incremento delle specie descritte. Ciononostante, l’analisi morfologica non sembra in grado di risolvere tutti i problemi di identificazione delle specie. Già erano note morfospecie comprendenti popolazioni con diverso grado di ploidia e/o diverse modalità riproduttive. Recentemente, mediante indagini molecolari, è stata riconosciuta la presenza di specie criptiche. Messa a punto la tecnica di estrazione di DNA da singoli animali e da singole uova, abbiamo pertanto ritenuto opportuno iniziare uno studio di DNA barcoding, considerando esemplari di due specie raccolti nel locus typicus ed in altre località. Le due specie considerate sono state Macrobiotus macrocalix (locus typicus Gaianello, Modena) e Macrobiotus richtersi (locus typicus Clare Island, Irlanda). Sulle popolazioni di queste due e di altre località sono state condotte indagini morfologiche e molecolari (mtDNA COI). Entrambe le analisi hanno confermato l’attribuzione a M. macrocalix di quattro popolazioni, tre italiane ed una svedese. In M. richtersi, differenze sono state invece rilevate a livello molecolare tra la popolazione di Clare Island e le diverse popolazioni italiane, risultate differenti anche tra loro.
2008
- Tardigrade resistance to space effects (tarse): first results of the mission life on foton-m3
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Guidetti, Roberto; Altiero, Tiziana; Bertolani, Roberto; A. M., Rizzo
abstract
Anhydrobiosis is a highly stable and reversible state of suspended life due to complete organism desiccation. Anhydrobiotic tardigrades show extraordinary resistance to physical and chemical extremes, far exceeding tolerance ranges of active animals. Consistent with these potentialities, the Mission LIFE on Foton M3 - TARSE (TArdigrade Resistance to Space Effects), part of the line ASSC of the ASI MoMa project, aimed to analyse the effects of space environment on this animal model. Four experiments have been carried out using Macrobiotus richtersi. In September 2007 desiccated (in microcosm or on paper) and hydrated tardigrades (fed or starved) have flown on Foton M3 for 12 days, using the facility Biokon (by Kayser Italia). As control, ground experiments miming the flight temperatures are currently running. To date we have complete results about survival and preliminary data on life cycle parameters. The highest survival rate has been obtained for desiccated specimens in microcosm (94.4±4.8%) and on paper (78.9±25.2%), and for hydrated starved animals (60.6±8.3%). The lowest survival rate has been recorded for hydrated fed animals (6.8±9.9%). During the flight: i) active females laid eggs, ii) several eggs hatched, iii) the hatching time was very short, and iv) newborns exhibited normal morphology and behaviour. After the flight, adults laid eggs and the reared newborns reached sexual maturity and laid eggs too. Currently we are analysing: i) genomic DNA quality, ii) Hsp expression, iii) oxidative stress. Studies on genomic DNA quality and oxidative stress will allow us to verify possible radiation effects, while Hsp expression will permit to investigate the role of this bioprotectant. Finally, ground experiments on RPM are settled to verify the eventual effects of microgravity.
2008
- TArdigrade Resistance to Space Effects (TARSE): primi risultati della missione LIFE su Foton-M3
[Abstract in Atti di Convegno]
Altiero, Tiziana; Guidetti, Roberto; Bertolani, Roberto; A. M., Rizzo; Rebecchi, Lorena
abstract
Il progetto TARSE, parte della linea ASSC del progetto MoMa dell’ASI ha proposto i tardigradi come modello da utilizzare in esperimenti nello spazio. Gli obiettivi specifici erano: verificare gli effetti dell’ambiente spaziale su sopravvivenza, cicli vitali, induzione di bioprotettori, danni al DNA dovuti a radiazioni o a stress da essiccamento. Sono stati condotti quattro esperimenti sull’eutardigrado Macrobiotus richtersi, con animali in stato essiccato (all’interno di un microcosmo o su carta) ed idratato (alimentati o a digiuno). Gli animali hanno volato per 12 giorni nella navicella spaziale Foton M3, utilizzando la facility Biokon (Kayser Italia). Le attività post-volo previste consistevano in analisi: della sopravvivenza, dei parametri del ciclo vitale, biochimiche e molecolari. Erano previsti, e in parte sono stati realizzati, esperimenti di controllo a terra, simulando la temperatura del volo, o la microgravità (con RPM). I tassi di sopravvivenza, simili a quelli degli esperimenti a terra, risultavano elevati per gli individui essiccati sia nel microcosmo 94,4±4,8%) che su carta (78,9±25,2%) e per gli animali idratati digiuni (60,6±8,3%). Simili erano anche le quantità di Hsp 70 riscontrate negli esperimenti a terra.Non sono stati evidenziati danni alla doppia elica di DNA. Durante il volo, le femmine attive hanno deposto uova, schiuse in gran numero e in tempi più brevi del controllo a terra; i giovani nati mostravano normale morfologia e comportamento.
2007
- Approccio molecolare, modalità riproduttive e specie criptiche nei tardigradi.
[Abstract in Atti di Convegno]
Bertolani, Roberto; Guidetti, Roberto; Cesari, Michele; Altiero, Tiziana; Rebecchi, Lorena
abstract
Gli studi molecolari hanno portato ad attribuire i tardigradi agli Ecdysozoa e confermato sia la loro appartenenza ai Panarthropoda, che la loro suddivisione in ordini. Ancora assai limitato è invece l’utilizzo della biologia molecolare per discriminare le loro specie. Numerosi sono, infatti, i ritrovamenti di tardigradi attribuibili alla medesima morfospecie, ma distinti in popolazioni unisessuate e bisessuate, spesso diverse anche per grado di ploidia. Le indagini condotte finora non hanno però consentito di stabilire con certezza se tra queste popolazioni vi fosse o meno flusso genico. Utilizzando come marcatore una sequenza di 640 bp del gene mitocondriale COI, sono state confrontate popolazioni riferibili all’eutardigrado Macrobiotus richtersi con diversa provenienza geografica (Modena e Trento) e verificate le loro modalità riproduttive. In entrambe le province sono state rinvenute, in località distinte, sia popolazioni anfimittiche (diploidi) che partenogenetiche telitoche (triploidi e ameiotiche). L’analisi delle sequenze ha rilevato notevole somiglianza nell’aplotipo delle popolazioni partenogenetiche, pur se geograficamente distanti, e forti differenze tra queste e le anfimittiche. Queste sono coerenti con quanto da noi già riscontrato tra popolazioni anfimittiche e partenogenetiche di un’altra morfospecie (Richtersius coronifer) utilizzando allozimi. La costanza e l’ampiezza delle differenze nell’aplotipo evidenziano che non c’è flusso genico tra le popolazioni e che siamo in presenza di specie criptiche. Data l’esistenza di numerose morfospecie di tardigradi con più modalità riproduttive, il loro studio a livello molecolare, associato a quello della loro distribuzione geografica, dovrebbero portare nuova luce sulla microevoluzione all’interno del phylum e, più in generale, sui microinvertebrati caratterizzati da forte dispersione passiva.
2007
- Energy allocation in two species of Eutardigrada
[Articolo su rivista]
Guidetti, Roberto; C., Colavita; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena
abstract
To improve our knowledge on life histories in tardigrades and the energy allocated for their reproduction and growth, we have studied two species (Macrobiotus richtersi and Hypsibius convergens) differing in evolutionary histories, diet and ways of oviposition. For both species we considered a bisexual population dwelling in the same substrate. In both species we investigated energy allocations in males with a testis rich in spermatozoa and females with an ovary containing oocytes in advanced vitellogenesis. The age of the specimens were estimated on the basis of buccal tube length and body size and the body and gonad areas were calculated using an image analysis program. In both species females reach a larger size than males. Macrobiotus richtersi has significantly longer buccal tube and wider body area than H. convergens. Statistical analyses show that buccal tube has a positive correlation with body area and gonad area. For an estimate of the relative energy allocated for reproduction in one reproductive event (relative reproductive effort = RRE), we have used the ratio between gonad area and body area. In males of both species, the absolute amount of energy and the RRE is statistically lower than that of females. Males and females of H. convergens have a RRE higher than those of M. richtersi. In M. richtersi, the gonad increases proportionally more when animals are large (old), whereas in H. convergens this direct relationship is not detectable. In M. richtersi the energy allocated for a reproductive event increases during the life of the females. In males, the increase of the gonad size is progressive during the animal life. In each reproductive event, females of H. convergens allocate a lower amount of energy in absolute value when compared to M. richtersi. Nevertheless, when considering the RRE, their investment is higher than that of M. richtersi.
2007
- Indagini sulla sopravvivenza ad essiccamento e stress termico e sulla ripresa della vita attiva in tardigradi colonizzanti ambienti a variabilità stocastica
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Altiero, Tiziana; Cesari, Michele; A., Frigieri; V., Lencioni; Bertolani, Roberto; Guidetti, Roberto
abstract
La possibilità di attuare la criptobiosi consente ai tardigradi di colonizzare ambienti estremi (deserti, montagne elevate, o regioni polari) preclusi alla maggior parte degli altri organismi e, nelle zone temperate, di vivere in habitat particolari caratterizzati dall’alternanza stocastica di periodi di siccità e pioggia, o di congelamento e scongelamento. Studi sulla criptobiosi nei tardigradi sono stati rivolti ad individuare le molecole bioprotettrici, soprattutto il trealosio, prodotte quando gli animali entrano in questo stato. Nostre indagini, basate sull’interazione tra osservazione in natura e sperimentazione in laboratorio, hanno riguardato l’effettiva capacità di sopravvivenza dei tardigradi in anidrobiosi e i relativi aspetti microevolutivi. Esse hanno portato all’individuazione di differenze nel tasso di sopravvivenza, sia tra specie, che tra popolazioni della stessa specie provenienti da aree geografiche diverse. Abbiamo ora inteso considerare gli effetti combinati di stress da essiccamento e da calore. Sono stati pertanto condotti alcuni esperimenti utilizzando Macrobiotus richtersi, eutardigrado facilmente reperibile nella lettiera di bosco sottoposta a ripetuti e imprevedibili eventi di disidratazione e reidratazione (oltre che a congelamento e scongelamento). Esemplari lasciati seccare all’interno di un campione di lettiera di bosco raccolto in natura e quindi ulteriormente stressati mantenendoli a 37°C per 21 giorni, non evidenziano diminuzioni significative della sopravvivenza dopo la reidratazione. Tuttavia, il tempo necessario per riprendere la vita attiva da parte di questi animali non resta uguale, ma aumenta in relazione diretta al tempo trascorso a 37°C. Diversamente, esemplari seccati in un campione di lettiera di bosco e stressati a 37°C per 21 giorni, ma mantenuti a diversi livelli di umidità relativa dell’aria (RH, 80%, 25%, circa 0%), mostrano, dopo reidratazione, una sopravvivenza inversamente proporzionale al valore di RH. Inoltre, il tempo necessario per la ripresa della vita attiva è direttamente proporzionale al valore di RH a cui gli animali stessi sono stati esposti. Un risultato simile (ma con sopravvivenza complessivamente minore) è emerso da animali essiccati sperimentalmente su carta a condizioni controllate e quindi sottoposti a 21 giorni di stress termico, sempre a 37°C. Alcuni autori sostengono che la criptobiosi, o almeno l’anidrobiosi, comporti un danno del DNA e quindi che la ripresa della vita attiva sia accompagnata da fenomeni riparativi del DNA stesso. Questo si accorderebbe con il maggior tempo necessario agli animali sottoposti a forti livelli di stress per riprendersi. Tuttavia, nostre indagini sul DNA estratto da esemplari di M. richtersi essiccati su carta e stressati a 37°C non hanno verificato la presenza di rotture dell’acido nucleico, indicando che la causa del ritardo nella ripresa della vita attiva deve essere ricercata in altri tipi di molecole.
2007
- New taxonomic position of several Macrobiotus species (Eutardigrada: Macrobiotidae)
[Articolo su rivista]
Guidetti, Roberto; Bertolani, Roberto; P., Degma
abstract
The main character distinguishing Minibiotus from Macrobiotus is the presence of peribuccal papulae instead of lamellae.However, most Minibiotus species also share a set of characters of the bucco-pharyngeal apparatus. This set isdefined by ten morphological features (the first seven common to all species, the last three to most of them): antero-ventralmouth (1), teeth in oral cavity absent or strongly reduced (2), a rigid and narrow buccal tube (3), buccal tube wallthickened below the point of insertion of stylet supports (4), stylet supports inserted at considerable distance from theposterior end of the buccal tube (5), short ventral lamina (6), short macroplacoid row length (7), a double curvature of thebuccal tube (8), first macroplacoid situated very close to the pharyngeal apophysis (9) and three almost rounded macroplacoids(10). We examined the original descriptions and/or the type material of several species belonging to the genusMacrobiotus that seemed to present this set of characters. It was concluded that several species should be transferredfrom Macrobiotus to Minibiotus. The following new combinations are proposed: Minibiotus subintermedius (Ramazzotti,1962) comb. n., Minibiotus pustulatus (Ramazzotti, 1959) comb. n., Minibiotus julietae (de Barros, 1942) comb.n., Minibiotus marcusi (de Barros, 1942) comb. n., Minibiotus granatai (Pardi, 1941) comb. n., Minibiotus allani (Murray,1913) comb. n., Minibiotus crassidens (Murray, 1907) comb. n. and Minibiotus acontistus (de Barros, 1942) comb.n.. As a result of these new combinations, the genera Minibiotus and Macrobiotus appear to be more homogeneous, buttheir monophyly has not yet been demonstrated. Further data are necessary to better analyze the systematic position ofMacrobiotus lazzaroi Maucci, 1986, Macrobiotus spertii Ramazzotti, 1957 and Macrobiotus striatus Mihelčič, 1949.
2007
- The mission Foton-M3 t.o evaluate the tardigrade resistance to space effects
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Altiero, Tiziana; Guidetti, Roberto; Bertolani, Roberto; A. M., Rizzo
abstract
Tardigrades are microscopic animals able to pass over dehydration stress entering anhydrobiosis (i.e. dramatically reducing their metabolism) in any stage of their life. Using this strategy, tardigrades survive to extremely warm and dry environments excluded to most animals. Anhydrobiosis also gives rise to resistance against other stresses (i.e. temperatures over 100°C, freezing and ionizing rays). Trehalose is involved in anhydrobiosis playing an important role to protect cells. This sugar is currently used as additive for protecting mammalian cells during cryopreservation. Other molecules (e.g. heat shock proteins, Hsps) seem to be further keys to understand the anhydrobiotic mechanisms.The study here proposed (TARSE: Tardigrade Resistance to Space Effects) is part of the line ASSC (Animal Space Stress and Countermeasures) of the ASI MoMa project. Its aim is to study the ability of tardigrades to survive to space environments using as a tool anhydrobiotic and hydrated specimens of Macrobiotus richtersi, in light to lead to a development of molecules or mechanisms required to stabilize cells. Animals will fly using the facility Biokon (by Kayser Italia) during the mission Foton-M3. As a ground control, identical replicates will be maintained in Modena laboratory. Particular emphasis will be placed on the resistance to desiccation and to radiation stresses. The specific goals are: i) to verify the effect of space environment on survival of both desiccated and hydrated tardigrades, ii) to detect bioprotectant (e.g. Hsps) induction, iii) to verify the eventual damages on DNA due either to radiation or desiccation stresses, and the ability to repair them.
2007
- Ultrastructure of the digestive system of Ramazzottius tribulosus and Macrobiotus richtersi (Eutardigrada) in relationship with diet
[Articolo su rivista]
A. M., Avdonina; N. M., Biserova; Bertolani, Roberto; Rebecchi, Lorena
abstract
The ultrastructure of the digestive system of tardigrades was already described in some species, but it has never been studied in relationship to the diet. Therefore, utrastructural analyses of the midgut and hindgut of the phytophagous Ramazzottius tribulosus and the zoophagous Macrobiotus richtersi have been made. In addition, the foregut of R. tribulosus has been also analyzed. For this part new ultrastructural details have been evidenced. Among them, distinct transverse pillar-like structures, lacking in the electron-dense and compact cuticle of the buccal tube; a hole or groups of holes sometime present in the buccal tube; a large cavity within each salivary glands, where secreted mucus is accumulated; one valve made up by folds of the pharynx and located at the transition from pharynx to esophagus, already found in the zoophagous Isohypsibius prosostomus. In both analyzed species the increase of midgut surface is realized by two orders of folds of the gut wall and by microvilli. In R. tribulosus there are many first-order folds and few second-order fold, whereas in M. richtersi we found an opposite pattern. A perithrophic membrane and microvilli with a well developed glycocalix are found only in the midgut lumen of R. tribulosus. The density of microvilli and the ratio between the real surface with microvilli and the hypothetic surface without microvilli is lower in the zoophagous M. richtersi and I. prosostomus than in the phytophagous R. tribulosus. All these data represent an indirect indication of differences in digestion physiology between phytophagous and zoophagous tardigrade species. The shape of the hindgut is similar in both species and in particular the lumen of the hindgut looks as a heart-like cavity with some narrow cell evaginations.
2006
- Cryobiosis survival in tardigrades.
[Abstract in Atti di Convegno]
Bertolani, Roberto; Rebecchi, Lorena; Boschini, Deborah; Guidetti, Roberto
abstract
Eight species of eutardigrades collected in different terrestrial and freshwater habitats and characterized by different anhydrobiotic capabilities have been submitted to freezing and thawing experiments. The aim was to test: i. the interspecific capability to survive cryobiosis and the differences in recovery time to active life; ii. the relationship between survival and cooling rates. Starting from a uniform condition of tardigrades maintained for 24 h in water at 14°C, the cooling was performed according to three different protocols. Experiment 1: replicates for each species considered were put in 4 ml of water, frozen at three temperatures (-9°C, -20°C and -80°C) and kept frozen for six days. Experiment 2: replicates of Ramazzottius oberhaeuseri and Amphibolus volubilis were put in 4 ml of water, frozen in liquid nitrogen for two minutes and then stored at –9°C. Experiment 3: replicates of R. oberhaeuseri were placed in different amounts of water (2 ml, 1 ml and 0.5 ml), frozen at three different temperatures as in experiment 1 and kept frozen for six days. Before thawing, all frozen animals were firstly put or maintained at –9°C and then thawed at 14°C. Animals were examined both after 2.5 h and 24 h, considering alive the animals with evident and coordinated body movements. In experiment 1, R. oberhaeuseri, A. volubilis, Macrobiotus areolatus and Macrobiotus richtersi show a high survival at any tested temperature. Hypsibius dujardini, Borealibius zetlandicus and Diphascon cf. scoticum show a lower survival and differences in survival among each temperature. Survival of Dactylobiotus parthenogeneticus is null at any tested temperature. In most cases, the recovery time increases with the fall of the temperature and differs among the species. The differences among the species seem clearly related to the habitat and above all to the capability to carry out anhydrobiosis, suggesting a strong relationship between anhydrobiosis and cryobiosis. In experiment 2, all specimens of both species did not survive to freezing at –196°C. In experiment 3, R. oberhaeuseri shows high survival also when the animals are frozen in less than 4 ml of water, even though a survival decrease is recorded between –9°C and –80°C for all tested water amounts. In general, the survival is lower when the water freezing time is shorter (corresponding to a higher cooling rate). Moreover, a negative relationship between the water freezing time and the recovery time has been found: the shorter the water freezing time, the longer the recovery time. A too short water freezing time does not allow survival. These results can be easily explained by the need to produce a sufficient amount of protectants, or not enduring too many damages.
2006
- Cysts of Amphibolus volubilis (Eutardigrada, Eohypsibiidae): seasonal dynamics and laboratory induction.
[Abstract in Atti di Convegno]
Guidetti, Roberto; Boschini, Deborah; Bertolani, Roberto; Rebecchi, Lorena
abstract
It is known that specimens of Amphibolus can carry out both cryptobiosis (anhydrobiosis and cryobiosis) and encystment and that they produce two types of cysts (type 1 and type 2). In Amphibolus nebulosus from Greenland, the type 1 cyst is related to winter and the type 2 to summer. In Amphibolus volubilis, found in Apennines (Monte Rondinaio, Italy), a detailed description of the encystment processes has been done, but not of the relationships between climatic factors and dynamics of the cyst 1 and cyst 2. Therefore, a study on seasonal dynamics of the A. volubilis cysts has been carried out with monthly samplings, from March 2003 up to March 2005. For each sampling, all specimens present in five-six replicates of 0.5 g of moss have been collected and analyzed.In all samplings, non-encysted and encysted animals (type 1 or type 2 cysts) have been found. The cyst trends are similar in the two considered years. Type 1 cysts have been found from November to March-April, but they were present in a very low percentage with respect to the total animals. Type 2 cysts have been found from June to October and are often more abundant than the non-encysted tardigrades. The two types of cysts never overlap. Correlation tests have evidenced that dynamics of type 2 cyst is positively related to the air temperature (T) and negatively related to the relative humidity (RH) of the air. The trend of type 1 cyst is negatively related to T, while no relationship to RH has been evidenced. The presence of non-encysted animals is negatively related to T and positively related to RH. Experiments of encystment induction have been performed in laboratory. In the same experimental conditions (same temperature, photoperiod, food and oxygen availability), non-encysted animals collected in April form type 2 cysts, whereas animals collected in November form type 1 cysts. The number of days to enter each type of cyst is related to experimental temperature. At the same temperature, the animals spent less time to enter in type 1 cyst than in type 2 cyst. In lab, the animals come out from type 2 cyst, if do not die, soon or later encyst again and enter always type 1 cyst.The data from nature and those from laboratory lead to conclude that, differently from what happens in anhydrobiosis and cryobiosis, climatic conditions do not directly affect encystment; but seasonal changing induces still unknown endogenous factors responsible of that kind of dormant stage.
2006
- Dynamics of long-term anhydrobiotic survival of lichen-dwelling tardigrades
[Articolo su rivista]
Rebecchi, Lorena; Guidetti, Roberto; S., Borsari; Altiero, Tiziana; Bertolani, Roberto
abstract
It is not rare to find in references that anhydrobiotic tardigrades can survive for more than a century. However, a closer look at the empirical evidence provides very little support that tardigrades are capable of surviving dried for such a long time. In order to resolve this discrepancy, we carried out a study to evaluate the long-term survival of naturally dried tardigrades. A large fragment of dry lichen (Xanthoria parietina) was collected in the field two days after a rainy day in 1999. The dry lichen was stored inside a paper bag in the laboratory at room temperature and humidity and under atmospheric oxygen exposure. Replicates of the dry lichen were re-hydrated after various time periods of storage, with all tardigrades extracted and the survivors enumerated. Five species of tardigrades were found, but two of them only occasionally. Ramazzottius oberhaeuseri, Echiniscus testudo and Echiniscus trisetosus were sufficiently represented for statistical analysis. At the beginning of the experiment 91.1% of R. oberhaeuseri and 71.7% of Echiniscus spp. were alive. R. oberhaeuseri survived up to 1604 days, while Echiniscus spp. lived up to 1085 days. Recovery after four years of anhydrobiosis has to be considered a very good long-term survival, which is important from an ecological and evolutionary point of view.
2006
- Encystment processes and the Matrioshka-like stage in a moss-dwelling and in a limnic species of eutardigrades (Tardigrada)
[Articolo su rivista]
Guidetti, Roberto; D., Boschini; Rebecchi, Lorena; Bertolani, Roberto
abstract
Tardigrades have two forms of dormancy, namely cryptobiosis and encystment. The encystment is a form of diapause known for a limited number of species of tardigrades and still little studied. To increase the knowledge on encystment, two species of eutardigrades from Italy have been considered: the moss-dwelling Amphibolus volubilis (Eohypsibiidae), and the limnic Dactylobiotus parthenogeneticus (Murrayidae). Cysts have been collected in nature, or induced under laboratory conditions. In the latter case, it was possible to follow the several steps of encystment processes. Two different types of cyst (type 1 and type 2) have been found in A. volubilis, while in D. parthenogeneticus only one type has been found. In general, the ovoid-shaped cysts are constituted by a series of cuticles surrounding the animals and resemble an onion or a Matrioshka Russian doll. In all three types of cyst, the encystment processes show both common and peculiar traits. Encystment begins with the discharging of the sclerified parts of the buccal-pharyngeal apparatus, as in the molting process, but without the loss of the old cuticle. Then, two or three new cuticles are serially synthesized, according to cyst type. In A. volubilis, the ultrastructure of these new cuticular involucra is similar to that of non-encysted animal cuticles, while in D. parthenogeneticus the ultrastructure of the new cuticular involucra differs from that of non-encysted animal cuticle. A modified buccal-pharyngeal apparatus has been observed both in type 2 cyst of A. volubilis and in the D. parthenogeneticus cyst.
2006
- Energy allocation in the reproductive events of Macrobiotus richtersi and Hypsibius convergens (Eutardigrada).
[Abstract in Atti di Convegno]
Altiero, Tiziana; Guidetti, Roberto; Bertolani, Roberto; Rebecchi, Lorena
abstract
The knowledge of life histories in tardigrades is still limited, while an evaluation of the energy allocation for their reproduction has been considered very little. To improve our knowledge on these topics, we have studied two species differing in evolutionary histories, diet and ways of oviposition. Macrobiotus richtersi (Macrobiotidae) is carnivorous and lays “free” ornamented eggs, while Hypsibius convergens (Hypsibiidae) is certainly not carnivorous and lays smooth eggs within the exuvium. For both species we considered a bisexual population dwelling in the same substrate, a beech leaf litter collected on the Apennines (Piane di Mocogno, Modena, Italy) at 1200 m a.s.l. Both species are iteroparous. In M. richtersi, the maturative patterns of male and female gonads follow the respective models proposed by Rebecchi & Bertolani (1994). In H. convergens the male germ cell maturation is continuous and follows the previous male model, whereas the female germ cell maturation does not strictly follow the stages described for M. richtersi and other eutardigrade species.With regard to the energy allocation, males with testis rich in spermatozoa and females with ovary containing oocytes in advanced vitellogenesis have been considered in both species. The age of those specimens has been estimated according to the buccal tube length. Their body and gonad areas have been evaluated with an image analysis program. In both species females reach a larger size than males. Macrobiotus richtersi has statistically longer buccal tube and wider body area than H. convergens. Statistical analysis evidences that the buccal tube length is positively related to the body area and to the gonad area. For an estimate of the relative energy allocated for the reproduction in one reproductive event (here called RRE = relative reproductive effort), we have used the ratio: gonad area/body area. In males of both species, the absolute amount of energy and, above all, the RRE is statistically lower than that of females. In M. richtersi, the RRE of both males and females is directly related to the age of the animal, whereas in H. convergens this direct relationship is not detectable. This means that in M. richtersi the energy allocation for a reproductive event increases during the life of the animal. In each reproductive event, due to their smaller size, in absolute value, females of H. convergens allocate a lower amount of energy with respect to M. richtersi, but if we consider the RRE, their investment results higher than that of M. richtersi.
2006
- Geonemy, ecology, reproductive biology and morphology of the tardigrade Hypsibius zetlandicus (Eutardigrada: Hypsibiidae) with erection of Borealibius gen. n.
[Articolo su rivista]
G., Pilato; Guidetti, Roberto; Rebecchi, Lorena; O., Lisi; Jg, Hansen; Bertolani, Roberto
abstract
The morphology, biology and geographic distribution of Hypsibius zetlandicus (Murray, 1907) are considered. LM and SEM analyses have been carried out on H. zetlandicus and other two species of Hypsibius, with particular emphasis on the buccal-pharyngeal apparatuses. Some peculiar characteristics of this apparatus in H. zetlandicus lead us to the erection of the new genus Borealibius, to which H. zetlandicus (Borealibius zetlandicus comb. n.) is transferred.In the light of new findings in polar, sub-polar and alpine regions and the available bibliographic references, we evidenced for this species a boreo-alpine distribution. The presence of uncommon phenomena for a tardigrade species have been observed analyzing traits of B. zetlandicus reproductive biology (presence of hermaphroditism and parental cares) and ecology (colonization of very different substrates).
2006
- Phenotypic variations in the life history of two clones of Macrobiotus richtersi (Eutardigrada, Macrobiotidae)
[Articolo su rivista]
Altiero, Tiziana; Rebecchi, Lorena; Bertolani, Roberto
abstract
A comparative study of life history traits of two clones (CDMr01 and CDMr02) of a triploid thelytokous apomictic population of the eutardigrade Macrobiotus richtersi has been carried out. Both clones were reared under the same lab conditions: temperature of 14 degrees C, photoperiod of 12 h/12 h (L/D), and nematodes ad libitum as food. Statistical analysis of the life history traits considered has indicated interclonal variability. The two clones were significantly different in the number of eggs per clutch (fertility), number of eggs laid per female per life span (fecundity), hatching percentage of eggs and hatching time. Similarities between clones have been observed with regard to life span, total number of ovipositions per life span, and age at first oviposition. In addition, significant differences in hatching time, with eggs hatched over a long period, were found within each clone. Interclonal variability in life history traits indicated the effects of genetic factors, whereas intraclonal variability reflected the effects of environmental factors. The evolutionary and adaptive significance of the life history phenotypic variations is discussed.
2006
- Risposte in modelli animali agli effetti dell’ambiente spaziale: i tardigradi, organismi resistenti a stress di ambienti estremi.
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Boschini, Deborah; Altiero, Tiziana; Bertolani, Roberto; Guidetti, Roberto
abstract
I tardigradi rappresentano un modello animale particolarmente valido per la comprensione dei meccanismi, a livello organismico e cellulare, di protezione dagli stress dell’ambiente spaziale. Sono infatti invertebrati microscopici (circa 0,3-0,5 mm) che per condurre vita attiva necessitano di almeno un velo d’acqua, ma quando questa non è disponibile, rallentano notevolmente, o sospendono, il metabolismo sopravvivendo essiccati (anidrobiosi), o congelati (criobiosi). Entrando in anidrobiosi producono bioprotettori (es. trealosio) che stabilizzano le membrane cellulari. In anidrobiosi resistono inoltre ad ulteriori stress, come ad esempio, temperature di 150°C, o vicine allo zero assoluto (-273°C), radiazioni ionizzanti 500 volte superiori a quelle che porterebbero all’immediata morte dell’uomo, atmosfere sature di CO2 e HNO3, immersione in alcoli e pressioni di 600 Mpa (Bertolani et al., 2004). I tardigradi attuano la criptobiosi (anidrobiosi e criobiosi) in qualunque fase del ciclo vitale; alcune specie possono essere allevate (Altiero & Rebecchi, 2001) risultando particolarmente longeve, tanto da superare l’anno di vita (Altiero, Rebecchi & Bertolani, 2006). Inoltre, a differenza di altri minuscoli metazoi, sono caratterizzati da divisioni cellulari anche nell’adulto. Indagini dell’U.O. sulle capacità criptobiotiche dei tardigradi (parzialmente finanziate da ASI, 2001) hanno consentito di dimostrare la presenza di differenze intra- ed interspecifiche nella sopravvivenza in anidrobiosi (Jönsson, Borsari & Rebecchi, 2001), la relazione fra tratti fenotipici dei tardigradi e sopravvivenza all’essiccamento (Jönsson & Rebecchi, 2002), la sopravvivenza a lungo termine in anidrobiosi (Rebecchi et al., 2006), la presenza di differenze interspecifiche nella capacità di resistere al congelamento (Guidetti et al., inviato).L’ambiente spaziale provoca sui viventi stress che accelerano il tasso di invecchiamento; per individuare strategie contro l’invecchiamento ed anche al fine di applicazioni biotecnologiche, viene qui proposto lo studio dei meccanismi molecolari che consentono ai tardigradi di resistere agli stress tipici di tale ambiente, in modo da acquisire conoscenze sui meccanismi di riparazione e mantenimento di cellule e organismi. In questa prospettiva si colloca dunque il progetto ASSC-TARSE (TArdigrade Resistance to Space Effect), inserito nell’area II (Cellule, Tessuti, Organi) del progetto MoMa. Il progetto ASSC-TARSE, utilizzando tardigradi in toto e loro cellule (storage cells) in coltura primaria, si propone di: i. valutare la sopravvivenza dei tardigradi dopo stress quali essiccamento, microgravità e radiazioni attraverso il confronto fra animali attivi e anidrobionti; ii. acquisire informazioni sulla fisiologia, la biochimica e il genoma dei tardigradi a seguito di tali stress; iii. acquisire informazioni sull’apoptosi. Durante l’elaborazione del progetto, l’U.O. ha messo a punto i protocolli per l’allestimento di colture primarie di storage cells, l’analisi del DNA genomico e l’analisi dell’espressione di Heat-shock proteins (Hsp) nei tardigradi attivi ed anidrobionti. La disponibilità di tali protocolli, oltre all’ottenuta dimostrazione che i tardigradi essiccati esprimono più Hsp70 rispetto a quelli attivi, rappresentano una valida base di partenza per il raggiungimento degli obiettivi sopraindicati. La piena realizzazione del progetto TARSE consentirà di ottenere i seguenti risultati: i. la rilevazione degli effetti dell’essiccamento, delle radiazioni e della microgravità sulla sopravvivenza sia di organismi in toto che di cellule in coltura; ii. la rilevazione di probabili danni al DNA genomico e dell’eventuale capacità di riparo; iii. la rilevazione dei fenomeni di apoptosi; iv. l’individuazione e la quantificazione di bioprotettori coinvolti nei meccanismi di resistenza all’essiccamento e alle radiazioni: Heat-sho
2006
- Tardigrades from Stelvio National Park, Central Alps (Italy)
[Abstract in Atti di Convegno]
Guidetti, Roberto; Bertolani, Roberto; B., Maiolini; Altiero, Tiziana
abstract
Tardigrades have been collected in different habitats in an Alpine glacial valley (Val de la Mare, Stelvio National Park, Trentino, Italy), between 2200 and 2300 m a.s.l. Submerged mosses of streamlets (2 samples), turf (1 sample) and mosses on rocks (2 samples) have been considered. These habitats hosted a very rich and diversified tardigrade fauna. Particularly rich in tardigrades were the submerged mosses, which comprised 9 species of eutardigrades belonging to 3 different families and 8 genera. Worthy of note are the first record of Borealibius zetlandicus in Italy (a species with a boreo-alpine geographic distribution) and the presence of two kinds of eggs in Murrayon pullari, a situation reported only once in tardigrades. Within the turf, a poorly known habitat, we found only one species, a Macrobiotus belonging to the “hufelandi group”, certainly new to science. Mosses on rocks contained 8 species (three echiniscid heterotardigrades and 5 belonging to two families of eutardigrades), different from those found in the other two habitats; three of them (two Ramazzottius and one Hypsibius) are probably new to science. In total, 18 species have been identified, four of which are new to science, one new to Italy and three new to the Trentino province. These results confirm the biogeographic significance of many tardigrades and suggest the need for more specific studies on tardigrade distribution focused on high altitudes and glacial areas of the temperate zones, which should be considered as biogeographic islands.
2006
- Tenth International Symposium on Tardigrada
[Esposizione]
G., Pilato; Bertolani, Roberto; G., Binda; Guidetti, Roberto; O., Lisi; Rebecchi, Lorena
abstract
The Tenth International Symposium on Tardigrada took place in Catania, Italy from 18 to 23 June 2006 and was held in the Auditorium of Benedettini, a fascinating historic building in Catania’s downtown. There were seventy-one participants at the Symposium, representing fourteen countries. The Symposium provided a unique opportunity both to review the progress of tardigrade studies and to allow all delegates to meet and to discuss topics of common interest. The symposium included thirty-four lectures and thirty-one poster presentations on a wide variety of topics in tardigrade biology. Topics included systematics, morphological and molecular phylogeny, faunal studies, biogeography, ecology, survival strategies, and modern molecular methodologies in tardigrade research. The twenty-four papers appearing in this special issue of the Journal of Limnology represent most of the contributors present in Catania.
2006
- Tenth International Symposium on Tardigrada: Catania, Italy 18-23 June 2006
[Articolo su rivista]
Pilato, G.; Bertolani, R.; Binda, M. G.; Guidetti, R.; Lisi, O.; Rebecchi, L.
abstract
2006
- Thermotolerance and thermal acclimation in active tardigrades.
[Abstract in Atti di Convegno]
Boschini, Deborah; Bertolani, Roberto; Rebecchi, Lorena
abstract
The ability of desiccated (anhydrobiotic) tardigrades to survive and to resist high temperature stresses (up to 100°C) is well-known, while the tolerance of active (hydrated) tardigrades to heat-shocks is still very little known. In order to increase our knowledge on thermal adaptations of active tardigrades, we have carried out lab experiments on three eutardigrade species to evaluate the ability to survive to heat-shock (considering lethal temperature - LT50 - and critical thermal maximum - CTmax), and the possibility of thermotolerance induction. We considered two terrestrial species, the moss-dwelling Amphibolus volubilis and the lichen-dwelling Ramazzottius oberhaeuseri, and one limnic species, Borealibius zetlandicus. These species differ each other in anhydrobiotic and cryobiotic abilities, substrate colonized.Starting from a uniform condition of tardigrades maintained for 24 h in water at 16°C, groups of hydrated tardigrades have been exposed for 1 hour to a heat-shock (different experiments from 26°C to 42°C). The presence of active animals (body movements) was evaluated immediately after heat-shock (t0), after 1h (t1) and after 24 h (t24) from heat-shock. Survival was represented by active animals at t24. For A. volubilis and R. oberhaeuseri the presence of active animals and survival was evaluated also after acclimation of 1 h (the first species at 28°C, the latter at 30°C) and subsequent heat-shocking to temperatures higher than 33°C. All species look thermotolerant, even though their survival significantly decreases with the increase of the stress temperatures. Both CTmax and LT50 are species-specific. The first one is 39.0°C for A. volubilis and 37.0°C for R. oberhaeuseri and B. zetlandicus. The latter is 35.1°C for A. volubilis, 33.6°C for R. oberhaeuseri and 33.0° for B. zetlandicus. The percentage of active animals changes according to the shock temperature and differs among the species. The number of animals with active movements often significantly increases between t0 and t1 for some temperatures, apart R. oberhaeuseri which shows a decrease at 28°C. There are not significant differences between t1 and t24 in the number of active animals, with the exception of an increase in A. volubilis at 30°C and 33°C. Both in A. volubilis and R. oberhaeuseri the acclimation produces significant survival increases of 10-40% for heat-shock temperature between 33°C–39°C, while at 40°C and 42°C there is not survival. These results demonstrate that tardigrades, even when active, have evident ability to survive heath stresses, even though sampled in different habitats and characterized by quite different cryptobiotic performances.
2005
- Diphascon (Diphascon) dolomiticum, a new species of Hypsibiidae (Eutardigrada) from Italy
[Articolo su rivista]
Pilato, G; Bertolani, Roberto
abstract
A new species of eutardigrade, Diphascon (Diphascon) dolomiticum sp. n., is described. It has three macroplacoids and microplacoid; claws short and stout; hind legs with basal margin indented; internal and external claws on the first three pairs of legs almost of the same length; anterior claws on the hind legs longer than the posterior claws.
2005
- Four new species of the Diphascon nobilei group (Eutardigrada, Hypsibiidae)
[Articolo su rivista]
G., Pilato; M. G., Binda; Bertolani, Roberto; O., Lisi
abstract
The existence of a group of species similar to Diphascon (Diphascon) nobilei is shown. These species have some common characteristics: a well-evident drop-shaped thickening between the buccal tube and the pharyngeal tube, pharyngeal bulb, more or less elongate, with three rod-shaped macroplacoids and microplacoid, claws of the hind legs different from those of the first three pairs of legs in having a very wide basal portion and indented basal margin, basal spurs also present on the external claws and, in some cases, also on the internal claws of the first three pairs of legs. Four new species of this group are described: Diphascon (D.) serratum, D. (D.) nelsonae, D. (D.) platyungue, and D. (D.) hydrophilum. They differ from one another in the dimensions and shape of the claws; in some cases the difference also affects the value of the ptd index relative to the insertion point of the stylet supports, the buccal and the pharyngeal tube length or the macroplacoid length.
2005
- Phylogenetic analysis of Macrobiotidae (Eutardigrada, Parachela): a combined morphological and molecular approach
[Articolo su rivista]
Guidetti, Roberto; A., Gandolfi; V., Rossi; Bertolani, Roberto
abstract
Combined analyses of morphological and molecular data were used to resolve phylogenetic relationships within Macrobiotidae (Eutardigrada). Morphological data were analysed using a cladistic approach with a matrix comprising 15 taxa with 17 characters to obtain a phylogenetic reconstruction. Molecular data were obtained by sequencing the cytochrome c oxidase subunit I gene in seven species of Macrobiotidae and one of Eohypsibiidae (used as outgroup). The morphological character defining the family, symmetrical claw on each leg, turns out to be plesiomorphic. Moreover, neither morphological nor molecular analyses supports a monophyletic clade for the subfamily Macrobiotinae, whereas both support a well defined evolutionary line (Murrayinae) within the family. We propose elevating the latter to family level (Murrayidae) while temporarily retaining as valid the family Macrobiotidae (amending its diagnosis, including within it only Macrobiotinae). Murrayidae opens an interesting evolutionary prospective, because the entire line has differentiated without sexual reproduction, constituting an example of evolution of asexual lineages.
2005
- Tardigrade taxonomy: an updated check list of the taxa and a list of characters for their identification
[Articolo su rivista]
Guidetti, Roberto; Bertolani, Roberto
abstract
Since the most recent monograph on Tardigrada by Ramazzotti & Maucci (1983), many changes have been introduced in the systematics of this phylum which has gone through different revisions and has been expanded by several new taxa. Moreover, the number of species is considerably increased (almost doubled to more than 960 species) and new families and genera have been created, while many taxa have been amended. The difficulty in finding a complete, updated list of taxa and the problems with putting together all the newly proposed taxonomic criteria, led us to compile an updated list of tardigrade taxa. This list is supplemented by a series of bibliographic references inherent in the synonymies and/or the amended diagnosis of the taxa occurred after 1983, and a list of the main characters used in the diagnosis of the species. These lists are aimed at helping not only the specialists studying this group, but also researchers interested in biodiversity and those who have to refer to this animal group.
2005
- Ultrastructure of the spermatozoon of Talpa romana (Mammalia, Lipotyphla)
[Articolo su rivista]
F., Beolchini; Rebecchi, Lorena; Bertolani, Roberto; E., Capanna
abstract
In this study, we used SEM and TEM to investigate the ultrastructure of spermatozoa from the cauda epididymis of Talpa romana. For comparison, we also analysed spermatozoa from the cauda epididymis of T. europaea captured in the same area. The male gamete of T. romana has a flattened head with an elliptic profile, consisting of a large acrosome and a nuclear region separated by a thin subacrosomal space. At the tip of the nucleus, the subacrosomal space ends in a finger-shaped projection. The tail includes a connecting piece, middle piece, principal piece and end piece. The male gametes of T. romana are substantially similar to those of T. europaea. A comparison with other species of insectivores permits extension of the similarity of sperm features to Scalopus aquaticus and Condylura cristata. Many spermatozoa from the cauda epididymis of T. romana and T. europaea have the tail bent at the annulus, and this is always associated with remnants of cytoplasmic droplets. This morphology is considered to be a common phenomenon.
2004
- Experiences with dormancy in tardigrades
[Articolo su rivista]
Bertolani, Roberto; Guidetti, Roberto; K. I., Joensson; Altiero, Tiziana; D., Boschini; Rebecchi, Lorena
abstract
Tardigrades often colonise extreme habitats, in which they survive using both types of dormancy: quiescence and diapause. Together with nematodes and bdelloid rotifers, tardigrades are known to enter quiescence (with several forms of cryptobiosis: anhydrobiosis, cryobiosis, anoxybiosis, osmobiosis) at any stage of their life cycle, from egg to adult. Entering anhydrobiosis, tardigrades contract their body into a so-called tun, loosing most of their free and bound water (> 95%), synthesizing cell protectants (e.g., trehalose, glycerol, heat shock proteins) and strongly reducing or suspending their metabolism. Our research on cryptobiosis focused on some ecological and evolutionary aspects. We evaluated: i) the long-term anhydrobiotic survival by comparing quantitative data on recovery from naturally induced desiccation in several species of tardigrades; ii) differences in survival patterns between species and populations by experimentally inducing anhydrobiosis and cryobiosis; iii) phenotypic factors affecting anhydrobiotic survival. As regards diapause, we considered encystment and eggs. Encystment involves at least the synthesis of new cuticular structures. Morphological changes during cyst formation are more complex than those involved in tun formation. We analyzed more in detail encystment processes, comparing a semiterrestrial with a limnic species. Several inter-specific differences have been identified, other than the production of two types of cysts in the semiterrestrial species. Our analysis of life history traits of a laboratory reared strain of a soil tardigrade revealed a particular hatching phenology that involved the production of both subitaneous and resting eggs. The latter need a cue to hatch (dehydration followed by re-hydration). In addition, the evolutionary meaning of dormancy in tardigrades is discussed.
2004
- Macrobiotus dariae sp n., a new species of eutardigrade (Eutardigrada, Macrobiotidae) from Cyprus
[Articolo su rivista]
Pilato, G; Bertolani, Roberto
abstract
Macrobiotus dariae sp. n. is a new species of eutardigrade characterized by a smooth cuticle with small pores; pharyngeal bulb with two macroplacoids and microplacoid; eggs with a reticular sculpture around small conical processes. The new species is similar to M. recens Cuenot, 1932, M. mongolicus Maucci, 1988, M. glebkai Biserov, 1990 and M. kozharai Biserov, 1999 from which it differs in some characters ( qualitative and quantitative) relating to both specimens and eggs.
2004
- Studies on groundwater tardigrades of Lessinian Massif (Northern Italy).
[Abstract in Atti di Convegno]
Guidetti, Roberto; D. M. P., Galassi; Bertolani, Roberto
abstract
Terrestrial tardigrades require a film of water around the body to conduct an active life. Therefore, in several cases the distinction between freshwater and terrestrial species is unclear as some species can tolerate a wide range of moisture regimes. Less than 6% of species are considered to inhabit permanent freshwater habitats. These species live as epiphyte on aquatic plants, benthic algal mats or among the minute voids of sediments in lotic and lentic waters. Tardigrades are sporadically reported from different groundwater habitats but little data are still available on their ecological affinity for this environment, as well as on their distribution and diversity in groundwater at different spatial scales. A stratified random sampling in both karstic and porous aquifers in the Lessinian Massif (northern Italy) gave the opportunity to asses their distribution patterns on a regional scale and to better define some ecological features of the collected species.Eight tardigrade species were collected in 29 of 129 sampling sites. These sites are located in five hydrogeographic basins in the selected region. Tardigrades were distributed in almost all the groundwater habitats; in saturated porous (wells), in saturated karst (only spring habitats) and in these cases always linked to the presence of unconsolidated sediments, and especially in hyporheic habitats, where they appeared with the highest frequency of occurrence and the highest abundance. They belong to six genera and two families of eutardigrades. Four species belong to typical limnic genera (Pseudobiotus, Thulinius and Dactylobiotus) and are characterized by claws longer than those of moss or soil-dwelling species. One species of Diphascon was already reported from groundwater, while two species of Macrobiotus and one of Hypsibius are easily found in terrestrial habitats. Some species of tardigrades collected in surface hyporheic habitats possess eye-spots. From an ecological point of view, most of them may be considered stygoxene or possibly stygophilous species. The morphological features of these species are similar to those of species living in surface freshwater on in the leaf-litter. This observation highlights the potential role of several habitats located at the interface surface/subsurface environments as potential migration ways for several species to enter groundwater. For the same reason, such a physical continuum and some degree of convergence in habitat features may determine the absence of clear morphological distinction between species living in such interface and those living in true groundwater.This research is partially granted by the EU-Pascalis project and by 60% MIUR from the University of Modena and Reggio Emilia.
2004
- Tardigrades in extreme habitats: morphological and molecular aspects in anhydrobiotic and encysted Amphibolus volubilis.
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Boschini, Deborah; Guidetti, Roberto; F., Callegari; Bertolani, Roberto
abstract
In terrestrial ecosystems tardigrades often inhabit transient systems that can support life only for a fraction of the year (e.g. arctic tundra, deserts, temporary ponds, mosses, lichens and leaf litter). Persistence of tardigrades in these harsh habitats is due to their ability to enter dormant states such as cryptobiosis and/or encystment. Cryptobiosis is directly induced by exogenous stimuli (desiccation: anhydrobiosis; freezing: cryobiosis) and it is promptly broken when the adverse conditions are removed. Encystment is under endogenous control and could be only indirectly induced by environment stimuli. Breaking encystment requires a specific cue that may or may not correspond to favourable environmental conditions.Amphibolus volubilis is a moss-dwelling tardigrade with a boreo-alpine distribution. Therefore, it represents a good model species to study the survival strategies in unpredictable environments. We verified that it is able both to enter cryptobiosis and to form cysts. Morphological changes of the body have been evidenced in anhydrobiotic tuns and cysts collected in nature from moss collected in a post-glacial valley (Northern Apennines, Modena, Italy, 1700 m a.s.l.) and/or induced in lab. Entering anhydrobiosis specimens contract longitudinally turning their body into a tun, lose most of their free and bound water and reduce or suspend their metabolism. The cyst is the result of a series of successive and continued morphological changes that are more complex than those involved in tun formation. Encystment involves repeated de novo synthesis of new cuticular structures (several cuticles with different ultrastructure, modified and unmodified buccal-pharyngeal apparatuses and claws) and a reduction of metabolism and loss of water lower than those involved in the anhydrobiotic state. The expression of Heat shock proteins (Hsps) have also been investigated in A. volubilis. Hsp 70 has been detected in active, anhydrobiotic and encysted specimens, evidencing that the synthesis of Hsp 70 in this species is not only related to desiccation stress. The synthesis of Hsp 70 was evidenced only in the anhydrobiotic state of the tardigrade Richtersius coronifer and related to tun formation (Ramløv and Westh, 2001).
2004
- Twelfth International Meiofauna Conference
[Esposizione]
F., Bertasi; Bertolani, Roberto; V. U., Ceccherelli; M., Colangelo; Guidetti, Roberto; Rebecchi, Lorena; Todaro, Mary Antonio Donatello
abstract
News insights on phylogenetic relationships and distribution patters of meiofaunal based on morphological and /or molecular analysis Coupling habitat complexity/heterogeneity and meiofaunal assemblagesMeiofauna in space and time Meiofauna trophic relationshipsDeep-sea meiofaunaResponse of meiofaunal taxa and/or assemblages to physical and/or chemical disturbanceMeiofauna in selected habitat
2003
- Reproductive modes and genetic polymorphism in the tardigrade Richtersius coronifer (Eutardigrada, Macrobiotidae)
[Articolo su rivista]
Rebecchi, Lorena; V., Rossi; Altiero, Tiziana; Bertolani, Roberto; P., Menozzi
abstract
Allozymes were assessed by starch gel electrophoresis in 3 populations of a eutar-digrade, Richtersius coronifer, with different reproductive modes. One population from Italy (with 2 sub-populations) was amphimictic and 2 populations (1 from Italy and 1 from Sweden) were parthenogenetic. All populations, irrespective of their reproductive mode, were diploid with the same chromosome number (2n=12) and had bivalents in the oocytes. Of the 14 loci analyzed, only 3 were polymorphic. The amphimictic population had a higher degree of genetic variability (mean heterozygosity >0.25) than the parthenogenetic populations (mean heterozygosity of the 2 populations <0.01). In all female populations, allele frequencies at all 3 loci deviated from Hardy-Weinberg equilibria due to heterozygote deficiency. These results support a hypothesis of automictic parthenogenesis in R. coronifer.
2003
- The gametogenetic cycle of two syntopic populations of moles: Talpa romana and Talpa europaea (Mammalia, Insectivora, Talpidae)
[Articolo su rivista]
F., Beolchini; Rebecchi, Lorena; Bertolani, Roberto; E., Capanna
abstract
The gametogenetic activity of two syntopic populations of moles, Talpa romana and T europaea (Mammalia, Insectivora, Talpidae), was compared. The testes and the ovaries of 42 specimens of T romana and of 41 specimens of T europaea were histologically characterised. Male gametogenetic activity was shown by the presence of spermatozoa in the epididymis. The diameter of seminiferous tubules was also measured. Female gametogenetic activity was evaluated on the basis of the number of secondary and pluristratified primary follicles in the ovary. Though not identical, the gametogenetic cycle of T romana largely overlaps that of T europaea. Moreover, for the two populations of moles a relationship between the duration of the reproductive activity and climatic and latitude-dependent parameters is suggested.
2003
- The spermatozoon of the Echiniscidae (Tardigrada, Heterotardigrada) and its phylogenetic significance
[Articolo su rivista]
Rebecchi, Lorena; A., Guidi; Bertolani, Roberto
abstract
The spermatozoon ultrastructure of four species of moss-dwelling Heterotardigrada belonging to four genera of Echiniscidae, namely Pseudechiniscus juanitae, Echiniscus duboisi, Novechiniscus armadilloides and Antechiniscus parvisentus, was investigated. In all species, the testicular male gamete is similar in morphology and in length. The spermatozoon is made up of along head, consisting of a cylindrical acrosome and an oval or rod-shaped nuclear region which contains a nucleus with osmiophilic and electron-dense chromatin, and a tapering tail, with a 9+2 axoneme. An elongated sack-like structure originates from the posterior part of the head, extending beyond the main axis of the cell and running parallel to the tail. It consists of two parallel tubular regions which sometimes form a strict double helix and contain two voluminous, free mitochondria with unmodified cristae. In addition, a voluminous vesicle is present laterally to the centriole or between the end of the nucleus and the beginning of the mitochondria, limited by two cytomembranes and filled with electron-lucent and granular material. The male gametes representative of these mossdwelling Echiniscidae are very similar to the spermatozoa of the marine Echiniscoididae Echiniscoides sigismundi. This close similarity emphasises that habitat changes have had little influence on the organisation of the sperm cell representative of Echiniscoidea. Spermatozoon characters which could be useful for phylogenetic studies on Tardigrada are discussed.
2003
- Thulinius, new generic name substituting for Thulinia Bertolani, 1981 (Tardigrada, Eutardigrada)
[Articolo su rivista]
Bertolani, Roberto
abstract
Due to a homonymy with a genus of Trematoda described two years before, the name Thulinia Bertolani, 1981 cannot be used for a genus of tardigrades. Therefore, Thulinius nomen novum is proposed for a genus of tardigrades (Eutardigrada, Hypsibiidae), in substitution of Thulinia, junior homonym. The complicated taxonomic history of the genus Thulinius and especially of one of its species is discussed. The characteristics of the genus and the main distinctive characters of the species are also repoted.
2002
- Banding techniques on tardigrade chromosomes: the karyotype of Macrobiotus richtersi (Eutardigrada, Macrobiotidae)
[Articolo su rivista]
Rebecchi, Lorena; Altiero, Tiziana; Bertolani, Roberto
abstract
This work represents the first attempt to define tardigrade chromosomes using banding techniques. Macrobiotus richtersi, a eutardigrade morphospecies with amphimictic diploid and thelytokous triploid cytotypes, was used as a model. Prime consideration was given to oocyte chromosomes because they are larger than those of spermatocytes and of mitotic chromosomes. With Giemsa staining, the chromatids of the 6 bivalents of the diploid cytotypes and those of the 17 18 univalents of the triploid cytotypes were very similar to each other and appeared rod- or flame-shaped. In the amphimictic strain, a chiasma was generally present in each bivalent at diplotene, whereas there were no chiasmata in the oocyte prophase chromosomes of the triploid strain. Both in diploid and triploid cytotypes, C-banding and fluorescence showed a heterochromatic centromeric band on the telomere of each chromosome oriented towards the spindle pole, indicating that all of them were acrocentric. Silver staining showed the presence of a NOR in only a pair of chromosomes, close to the centromeric C-banded site. NOR was particularly evident in the oocyte prophases. Other silver positive regions, corresponding to the kinetochore, were located on all other chromosomes on the telomeres towards the spindle pole.
2002
- First record of tardigrades within hypogeal caves
[Articolo su rivista]
Bertolani, Roberto
abstract
Tardigrades are repoted for the firs timewithin non-marine caves. They were collected in underground streams, or pools, or puddled formed by the dripping of water. The material came from some disctricts in Northern Italy and from a locality in Croatia. Natural caves and galleries dug during the First World War were examined and five species of tardigrades were identified. Two of them were abundant, demonstrating that they do not represent an incidental element in the caves.
2001
- An evolutionary line of the Macrobiotinae (Tardigrada, Macrobiotidae): Calcarobiotus and related species
[Articolo su rivista]
Guidetti, Roberto; Bertolani, Roberto
abstract
Three species of Macrobiotus (M. gildae, M. polygonatus and M. eugranulatus) were re-examined. Based on their synapomorphies with Calcarobiotus, they are ascribed to that genus. Within Calcarobiouts two phyletic lines are detected on the basis of the claw morphology. Therefore a new subgenus is erected: Calcarobiotus (Discrepunguis) subgen. n. constituted by C. (D.) polygonatus comb. n., and C. (D.) eugranulatus comb. n.; the subgenus Calcarobiotus (Calcarobiotus) includes C (C) filmeri, C. (C) occultus, C. (C.) imperialis and C. (C.) gildae comb. n.
2001
- Evolution of the reproductive mechanisms in tardigrades - A review
[Articolo su rivista]
Bertolani, Roberto
abstract
Although tardigrades can reproduce only through gametes they have exploited several modes of reproduction, which may be determined by their environment. Marine species (mainly heterotardigrades) are gonochoristic; hermaphroditism is only cited once, and parthenogenesis is unknown. In many cases females mature one egg at a time throughout adult life, whereas males are semelparous. Gonochorism is still present in limno-terrestrial species, while sporadic hermaphroditism occurs in several eutardigrade families. Thelytoky is the most common mode of reproduction in non-marine Tardigrada. Females are iteroparous, laying groups of eggs (free or in the exuvium), while males are semelparous (in a limnic species) or iteroparous with a continuous or cyclical maturation of the spermatozoa (in species from moss and leaf litter). Self-fertilisation appears to characterise hermaphroditic species, found in freshwater, mosses, leaf litter and soil. Egg maturation in these species is similar to that of the gonochoristic species, while spermatozoa mature in appreciable numbers before the oocytes, subsequently maturing continuously but in small numbers over the life of the animal. Parthenogenesis in limno-terrestrial tardigrades always appears continuous. In many species only females occur, but morpho-species populations may be found with both bisexual amphimictic (diploid) and unisexual thelytokous (often but not always polyploid) cytotypes. We can hypothesise that with the evolution of cryptobiosis and passive dispersal unstable and isolated habitats may favour parthenogenesis and self-fertilisation, as both reproductive modes allow colonisation of a new territory by a single individual. Parthenogenesis and hermaphroditism do not occur in the same species, and we can surmise that self-fertilisation will only evolve where parthenogenesis has never occurred.
2001
- Facts and fiction about long-term survival in tardigrades
[Articolo su rivista]
K. I., Jonsson; Bertolani, Roberto
abstract
Tardigrades have achieved a widespread reputation for an ability to survive more than a century in an inactive, ametabolic state called cryptobiosis, However, a closer look at the empirical evidence provides little support for the claim that tardigrades are capable of century-long survival. Instead, current evidence suggests that a decade may more realistically represent the upper limit of cryptobiotic survival in the most resistant tardigrades.
2001
- Phylogenetic relationships in the Macrobiotidae (Tardigrada : Eutardigrada : Parachela)
[Articolo su rivista]
Guidetti, Roberto; Bertolani, Roberto
abstract
Characters of the claws, buccal-pharyngeal apparatus and ultrastructure of the cuticle have been examined to identify phyletic relationships within the Macrobiotidae. Several apomorphies have been identified. The resulting cladogram shows two main phyletic lines within the family, corresponding to the subfamilies Macrobiotinae and Murrayinae. The relationships among the genera of the Murrayinae are resolved, whereas in the Macro biotinae five main phyletic lines are identified, whose relationships are still unknown. Pseudodiphascon and Macrobiotus appear to be polyphyletic genera.
2001
- Tardigrades as a model for experiences of animal survival in the space.
[Articolo su rivista]
Bertolani, Roberto; Rebecchi, Lorena; Joensson, Ki; Borsari, S; Guidetti, Roberto
abstract
In this paper the biological characteristics of tardigrades are discussed in term of their ability to tolerate the stresses typical of the environmental space.
2001
- The Tardigrades of Emilia (Italy). III. Piane di Mocogno (Northern Apennines).
[Articolo su rivista]
Guidetti, Roberto; Bertolani, Roberto
abstract
Samples of leaf litter, mosses and lichens were collected in a beech forest at Piane di Mocogno (Emilia, Italy), 1200 m asl. The tardigrade community of the leaf litter was similar to that found in this substrate in Italy and in the U.S.A. At Piane di Mocogno the species association within the leaf litter was different from that in mosses and lichens (which have similar fauna), confirming that very different communities characterise different substrates such as leaf litter and mosses. During this faunal analysis, six species of tardigrades were found for the first time in this area. The presence of Microhypsibius bertolanii (first record in leaf litter and in Italy) and Eohypsibius nadjae are note worthy. Ornamented eggs in an exuvium of Hypsibius cf. scabropygus were also recorded for the first time.
2000
- A New Eutardigrade (Tardigrada: Milnesiidae) in amber from the Upper Cretaceous (Turonian) of New Jersy
[Capitolo/Saggio]
Bertolani, Roberto; D., Grimaldi
abstract
The oldest true tardigrade known thus far, Milnesium swolenskyi n. sp., is described on the basis af a single, well-preserved specimen in amber from Turonian of New Jersey. The new species bears ab extremely close similarity to the living, widespread species Milnesium tardigradum Doyère. Antiquity of the Tardigrada sensu lato, as based on the existence of stem-group tardigrades from the Cambrian, corresponds with our discovery of a modern lineage of eutardigrade that has persisted for at least 90 million years (Ma).
2000
- Cuticle structure and systematics of the Macrobiotidae (Tardigrada, Eutardigrada)
[Articolo su rivista]
Guidetti, Roberto; Rebecchi, Lorena; Bertolani, Roberto
abstract
The cuticle of tardigrades is characterized by three main layers: epicuticle, intracuticle and procuticle. Pillars are present in the epicuticle of almost all heterotardigrades, but these structures are also known in a few species of eutardigrades. The apparent heterogeneity of the cuticular ultrastructure in several species of the Macrobiotidae (Eutardigrada) prompted us to analyse the structure of the cuticle in this family. Eleven species in several genera were investigated with light and/or electron microscopy. All the species of the genera Murrayon and Dactylobiotus showed pillars in the epicuticle, whereas the examined species of Macrobiotus, Richtersius and Xerobiotus completely lacked pillars. Therefore, in the Macrobiotidae, in contrast to what appears with light microscopy, the cuticle is homogeneous within each genus examined at the electron microscopic level. Considering the absence of pillars in the Macrobiotidae a synapomorphy, we propose the erection of two new subfamilies. Macrobiotinae subfam. n. is characterized by the absence of pillars in the epicuticular layer and includes, in addition to the genera Macrobiotus, Xerobiotus and Richtersius, the genera Pseudohexapodibius, Adorybiotus, and probably also Minibiotus, Calcarobiotus and Pseudodiphascon. Murrayinae subfam. n. is characterized by the presence of pillars in the epicuticular layer and includes the genera n Murrayon, Dactylobiotus and, probably, Macroversum.
2000
- Effects of a sulfonylurea herbicide on soil microarthropods
[Articolo su rivista]
Rebecchi, Lorena; Sabatini, Maria Agnese; C., Cappi; Grazioso, Pasqualina; A., Vicari; G., Dinelli; Bertolani, Roberto
abstract
The short-term effects on soil microarthropods of the herbicide triasulfuron, belonging to the chemical class of sulfonylureas, were evaluated in two fields which had never been treated with sulfonylureas, and were cultivated with winter wheat. In particular, the effects of single applications at rates corresponding to two- (rate 2) and sixfold (rare 6) the recommended agricultural rare (7.5 g active ingredient ha(-1)) were analysed and compared with controls. The changes in the populations of the main groups of microarthropods were evaluated. Rate 2 had very low effects, whereas rate 6 produced a significant decrease in the number of microarthropods, Acarina and Collembola in the surface soil layer (0-7.5 cm). The Collembola were analysed at the species level. Statistical analysis revealed significant differences only for a few species, and only after treatment with the highest rate of triasulfuron. Finally, the results of the field tests were compared to those of laboratory tests carried out previously, which examined the effects of the same herbicide on a collembola species.
2000
- Female gonad of moles, genus Talpa (Insectivora, Mammalia): Ovary or ovotestis?
[Articolo su rivista]
F., Beolchini; Rebecchi, Lorena; E., Capanna; Bertolani, Roberto
abstract
The female gonads of moles (genus Talpa) are composed of a cortex, functioning as an ovary, and a medulla, which is structurally similar to that of the testis. In the female reproductive apparatus there are masculine glandular annexes, such as a bilobate prostate, two Cowper glands, and a penis-like clitoris. All these features have recently led to the hypothesis of the presence of hermaphroditism due to sex-reversal in Talpa. The purpose of this study is to understand the functional significance of the structural organization of the female gonads in order to verify this hypothesis. Histological, histochemical and ultrastructural analyses have been carried out on several gonads of both sexes of two species: T. europaea and T. romana, including three fetuses. In both species, the cortical region of the female gonad shows a regular oogenetic activity. While the medulla is composed of interstitial cells that are partly organized in cord-like structures, no spermatogenetic activity has been ever observed inside of them. A histochemical analysis shows that in both sexes the interstitial cells secrete steroids, presumably estrogens as well as androgens. The presence of androgens in the female gonads would therefore explain the persistence of male glandular annexes in the female reproductive apparatus and both the sexual and behavioral monomorphism typical of the genus Talpa. Nonetheless, the female gonad of moles is a real ovary and a well-defined gonochorism exists. Therefore, there is no reason to assert the presence of hermaphroditism due to sex reversal. J. Exp. Zool. 286:745-754, 2000.
2000
- Maturative pattern of the ovotestis in two hermaphrodite species of eutardigrades
[Articolo su rivista]
Rebecchi, Lorena; Guidi, A; Bertolani, Roberto
abstract
We studied the maturative pattern of the ovotestis and the reproductive cycle of two hermaphrodite species of eutardigrades belonging to different families and collected independently from a chestnut litter. A long-term study on Macrobiotus joannae (Macrobiotidae), collected monthly, and a short-term study on Amphibolus weglarskae (Eohypsibiidae) were carried out. In both species the reproductive apparatus is represented by an ovotestis and by a short gonoduct. A caudal sack-like evagination of the ovotestis was found only in M. joannae. The size of the gonad varied in relation to the body size and degree of maturation of the germinal elements. In both species the maturative pattern of the ovotestis can be subdivided into four stages. The first stage includes three phases (undifferentiated, male and previtellogenic phases), whereas stages 2-4 correspond to the stages of vitellogenesis. Groups of 3-8 oocytes mature in strict relation to the molting cycle. In both species there are at least two cycles of egg production, indicating that hermaphroditic tardigrades are iteroparous. Apart from the first two phases of stage 1, all stages simultaneously possess male and female germinal elements which are not separated by barriers. The gonad is exclusively male only in relatively small specimens of both species, indicating that the male phase (m) is present only in the first reproductive cycle. The contemporary presence of mature oocytes and spermatozoa in close contact with each other is evidence that tardigrades are simultaneous hermaphrodites, and it suggests the existence of self-fertilization. This conclusion allows us to view our results in the light of predictions from current theories on sex energy allocation in hermaphrodite and gonochoristic tardigrades. Lastly, we compared the reproductive cycle of these two hermaphroditic species and those of a gonochoristic species belonging to the same genera.
2000
- Tardigrada
[Capitolo/Saggio]
Rebecchi, Lorena; A., Guidi; Bertolani, Roberto
abstract
In the chapter the various characteristics of tardigrades related to reproduction are reported: anatomy of the male reproductive systems and spermatozoan morphology; maturation pattern and reproductive physiology; fertilization, phylogeny.
1999
- Ecological and faunistic studies on tardigrades in leaf litter of beach forests
[Articolo su rivista]
Guidetti, Roberto; Dr, Nelson; Bertolani, Roberto
abstract
Tardigrades in leaf litter were collected from beech forests on Roan Mountain (TN, U.S.A.) and Modenese Apennine (Italy) at different altitudes and during different seasons. Twenty-six species of eutardigrades and 6 species of heterotardigrades were found on Room Mountain and 20 species of eutardigrades on Apennine. In both cases the tardigrade communities showed great biodiversity and a similar species composition, represented by hygrophilous and eurytypic taxa. Differences in the number of specimens and the species composition were found, related to substrate layers, altitudes and seasons.
1999
- Re-description of the genus Pseudobiotus (Eutardigrada, Hypsibiidae) and of the new type species Pseudobiotus kathmanae sp. n.
[Articolo su rivista]
Dr, Nelson; Nj, Marley; Bertolani, Roberto
abstract
Re-examination of the lectotype of Macrobiotus augusti Murray, 1907 and the subsequent transfer of the species to Thulinia necessitated the designation of a new type species for the genus Pseudobiotus. We are describing Pseudobiotus kathmanae sp. n. as the proposed new type species since these were the original specimens used to describe the genus Pseudobiotus. The other two species are either very uncommon (P. matici) or described only from a very short description of other authors and without type material (P, megalonyx). The presence of about 30 peribuccal lamellae, the shape and size of the dorsal and ventral buccal apophyses (crests), and the Isohypsibius-type claw distinguish Pseudobiotus from other genera. Pseudobiotus kathmanae differs significantly from the other two species in the genus, P. matici (Pilato, 1971) and P. megalonyx (Thulin, 1928), in a number of characters. The new species differs from P. matici particularly in the claws; the external and internal claws of P. matici are markedly different in size and shape, whereas they are similar in P. kathmanae. The number of macroplacoids easily distinguishes P. megalonyx, which has only 2 macroplacoids (and the second is peculiarly the longest), from P, kathmanae, which has 3.
1999
- Re-description of the genus Thulinia (Eutardigrada, Hypsibiidae) and of Thulinia augusti (Murray, 1907) comb. n.
[Articolo su rivista]
Bertolani, Roberto; N., Marley; D. R., Nelson
abstract
The genus Thulinia has been re-considerd, also on the basis of the analysis of the type material of Pseudobiotus augusti. This material allows to attibute this species to the genus Thulinia, which is re-described.
1999
- Spermatozoon morphology of three species of Hypsibiidae (Tardigrada, Eutardigrada)and phylogenetic evaluation
[Articolo su rivista]
Rebecchi, Lorena; Bertolani, Roberto
abstract
The spermatozoan ultrastructure of the gonochoristic eutardigrades Pseudobiotus megalonyx, Ramazzottius tribulosus and Ramazzottius oberhaeuseri (Hypsibiidae, Hypsibiinae) are described and illustrated. The two species of the same genus have very similar spermatozoa, whereas the two genera differ widely in male gamete organization. The testicular spermatozoon of Pseudobiotus has a thread-like configuration and is made up of a small comma-shaped acrosome, a helical nucleus and a tail with terminal tuft; no middle piece or neck and mitochondria were observed. The testicular spermatozoon of Ramazzottius shows an evident rod-shaped acrosome, a cork-screwshaped nucleus and a short tubular middle piece containing a mitochondrial sleeve; moreover, the tail splits terminally into a tuft. Functional considerations and phylogenetic comparisons are made on the basis of sperm morphology.
1999
- Tardigrada
[Capitolo/Saggio]
Bertolani, Roberto; Rebecchi, Lorena
abstract
In the chapter the various characteristics of tardigrades related to reproduction are reported: modes of reproduction and sex; anatomy of the reproductive systems and germ cell morphology; maturation pattern and reproductive physiology; fertilization; development.
1998
- Chromosome c-banding and Ag-NOR pattern in tardigrades
[Abstract in Atti di Convegno]
Rebecchi, Lorena; Altiero, Tiziana; Bertolani, Roberto
abstract
The first data on tardigrade chromosomes were derived from histological sections (Henneke 1911; von Wenck 1914). Specific studies were performed in the early seventies on animals stained in toto with acetic lactic orcein and squashed (Figs. 3-4; Bertolani 1971, 1975, 1982). Besides the definition of the chromosome number of several species (often n = 5 or n = 6), the main results were the identification of the polyploidy (triploidy and tetraploidy) and the definition of the cytology in the oocyte maturation of the parthenogenetic animals. Chromosomes always appeared small, without an evident centromere and similar to each other in the same plate and among the species. Oocyte chromosomes were clearly larger than those of the spermatocytes and of the mitotic divisions. More recently, Giemsa staining was applied to the eutardigrade Xerobiotus pseudohufelandi, in which diploid, triploid and tetraploid cytotypes were identified (Rebecchi, 1991). Triploidy and tetraploidy in tardigrades had been confirmed on the basis of the DNA content (Bertolani et al. 1987, 1994). Giemsa staining provides good details of the chromosome shape and confirms that M. richtersi is characterized by a chromosome set made up of very similar elements. Sex chromosomes are not recognizable.The kind of chromosome arrangement along the spindle fibers and the presence of a heterochromatic region on a telomere, evidenced by C-banding, allow us to conclude that all chromosomes of M. richtersi are acrocentric.There is only one NOR, localized on one extremity of one chromosome pair. It is evident in the oocyte prophases. In the oocyte metaphases the NOR could correspond to the most intense terminal dots that often characterize one of the six bivalents. As in other animals, the NOR coincides or is just adjacent the C-band site. The silver-positive regions located on one of the telomeres of all the other chromosomes of M. richtersi should correspond to the kynetochore, whereas the fainter regions located on the other telomere of all five bivalents resemble the “telochore” evidenced in the grasshoppers (Suja and Rufas 1994).
1998
- Side effects of the herbicide triasulfuron on collembola under laboratory conditions
[Articolo su rivista]
Sabatini, Maria Agnese; Rebecchi, Lorena; C., Cappi; A., Guidi; G., Dinelli; A., Vicari; Bertolani, Roberto
abstract
Triasulfuron, a member of the sulfonylureas class of herbicides, was tested under laboratory conditions on the collembolan Onychiurus pseudogranulosus. Pure triasulfuron and commercial formulations at different rates (starting from a dose about 5 times the recommended agricultural rate) were tested separately on one-week old juveniles and adults reared in the laboratory. The persistence of the herbicide at the end of the trials lasting 30 and 60 days was verified by HPLC analysis. Laboratory tests indicated that only the rates exceeding 500 times the soil concentration expected soon after field application of the herbicide directly affected the tested species. (C) 1998 Elsevier Science Ltd. All rights reserved.
1997
- Laboratory and field approaches to evaluate the effects of the herbicide triasulfuron on Collembola.
[Abstract in Rivista]
Rebecchi, Lorena; C., Cappi; Sabatini, Maria Agnese; Grazioso, Pasqualina; A., Guidi; A., Vicari; G., Dinelli; Bertolani, Roberto
abstract
The effects of the herbicide triasulfuron on Collembola are evaluated in laboratory and field studies.
1997
- Long-term effects of three different continuous tillage practices on Collembola populations
[Articolo su rivista]
Sabatini, Maria Agnese; Rebecchi, Lorena; C., Cappi; Bertolani, Roberto; B., Fratello
abstract
The long-term effects on Collembola populations of three types of soil tillage (minimum tillage, conventional ploughing to a depth of 25 cm and conventional ploughing to a depth of 50 cm), with four-year rotation (sugar beet, winter wheat, maize, winter wheat), were studied. The responses to rate of N fertilization were also tested. The analysis, which started after 15 years of continuous treatment and extended over a four-year period, revealed very large variations in Collembola abundance in the various years, but found very few significant treatment effects on overall abundances of Collembola. However, analysis carried out at the species level did reveal differences related to tillage; some species were significantly more abundant in plots with minimum tillage and others in plots with conventional ploughing. Moreover, N fertilization affected some species.
1996
- Leg and claw adaptations in soil tardigrades, with erection of two new genera of Eutardigrada, Macrobiotidae: Pseudohexapodibius and Xerobiotus
[Articolo su rivista]
Bertolani, Roberto; Biserov, Vi
abstract
We interpret reduction of the claws on the fourth pair of legs as a convergent adaptation of interstitial soil-dwelling tardigrades. The eutardigrades Hexapodibius degenerans, Macrobiotus pseudohufelandi, and M. xerophilus are re-examined and H. degenerans re-described. Due to the absence of true claws on the fourth pair of legs and to the symmetry of its claws on the first three pairs of legs, H. degenerans is attributed to a new genus, Pseudohexapodibius, belonging to the family Macrobiotidae. On the basis of the peculiar type of claws, without a distinct peduncle, M. pseudohufelandi and M. xerophilus are attributed to another new genus of Macrobiotidae, Xerobiotus.
1996
- Phylogenetic significance of egg shell variation in tardigrades
[Articolo su rivista]
Bertolani, Roberto; Rebecchi, Lorena; S. K., Claxton
abstract
Freshwater and semiterrestrial tardigrades produce either smooth shelled eggs laid in the exuvium or ornamented eggs laid freely, in contrast to the more primitive marine heterotardigrades which have smooth shelled free-laid eggs. Data are presented on the observation of free-laid ornamented eggs in the primitive non marine heterotardigrade genus Oreella and in a number of eutardigrade genera including Eohypsibius, Amphibolus, Minibiotus and Macrobiotus. These findings have provided a sound basis for the formulation of a hypothesis in which the evolution of the tardigrade egg can be explained by two separate events. The first is the acquisition of ornamentation and the second is the utilization of the exuvium for oviposition with subsequent loss of egg ornamentation. This hypothesis is consistent with new taxonomic arrangements within eutardigrade families and genera (based on character) of the animals) which have led to a more uniform assortment in terms of egg types. This means that egg type (smooth or ornamented) becomes a valid taxonomic character at the generic level.
1996
- The tardigrades of Emilia (Italy). II. Monte Rondinaio. A multihabitat study on a high altitude valley of the Northern Apennines.
[Articolo su rivista]
Bertolani, Roberto; Rebecchi, Lorena
abstract
The tardigarde fauna of a small galcila valley on Northern Apennines were investigted. Tardigrades from mosses, lichens, leaf-litter, tuft and water were considered. New tardigrade species were described.
1995
- La lavorazione del terreno e i suoi effetti sulle comunità di microartropodi del suolo
[Relazione in Atti di Convegno]
Bertolani, Roberto; Sabatini, Maria Agnese; Rebecchi, Lorena; Grazioso, Pasqualina; B., Fratello
abstract
We performed a study on the long-term effects of three types of soil tillage practices and enrichment with two doses of nitrogen fertilizers on soil microartropods. The study carried out in two succesive yeras found no significance differences in the overall population densities of Acarina or Collembola to the species level revealed differences to tillage. it is important that in studeis on agroecosytems at least one of the principal soil micorarthropod taxa be analysed at level species.
1995
- Tardigradi della Sardegna e di alcune piccole isole circum-sarde.
[Articolo su rivista]
Bertolani, Roberto; A., Guidi; Rebecchi, Lorena
abstract
We carried out a faunsitic study on limnic and terrestrial tardigardes from Sardinia and its surroundings samm islands. The study led to the identification of 34 species, including Bryodelphax iohannis, Macrobiosyu biserovi and Macrobiotus serratus, species new for science. Attention is focused on large number of ubiquitous or widespread species.
1994
- DORYPHORIBIUS-KOREANUS, A NEW SPECIES OF TARDIGRADA FROM KOREA
[Articolo su rivista]
Moon, Sy; Kim, W; Bertolani, Roberto
abstract
Doryphoribius koreanus, a new tradigrade species collected from terrestrial mosses and freshwater habitats in Korea, is described. The present new species mainly differs from the other species of the genus Doryhoribius in the following characteristics: smooth cuticle, two macroplacoids, presence of lunules only in the internal or anterior claws of legs, and very reduced buccal armature.
1994
- Faunistic study in the karst complex of Frasassi.
[Articolo su rivista]
Bertolani, Roberto; Manicardi, Gian Carlo; Rebecchi, L.
abstract
Data regarding faunistic analyses in the karst complex of Frasassi are reported.
1994
- Faunistic study in the karst complex of Frasassi (Genga, Italy)
[Articolo su rivista]
Bertolani, Roberto; Manicardi, Gian Carlo; Rebecchi, Lorena
abstract
La fauna cavernicola del complesso carsico di Frasassi è stata studiata per avere infromazioni dettagliate sulla popolazione aniamle ipogea.
1994
- MATURATIVE PATTERN OF OVARY AND TESTIS IN EUTARDIGRADES OF FRESH-WATER AND TERRESTRIAL HABITATS
[Articolo su rivista]
Rebecchi, Lorena; Bertolani, Roberto
abstract
We studied the life history of tardigrades with a particular focus on the maturative patterns of the ovary and testis. Specimens collected in nature belonging to four species of one freshwater and two semiterrestrial genera of eutardigrades were examined. The females of all examined species are always iteroparous; they have several maturative cycles with synchronously developing oocytes. Four maturative stages can be distinguished in each ovarian cycle, which is clearly correlated with moulting. In contrast, gametocyte maturation does not seem to be correlated with moulting in males and varies markedly in the considered genera. The testes of adult specimens of Macrobiotus always contain both mature spermatozoa and cells at earlier stages in spermatogenesis (continuous maturation). The testis of Pseudobiotus megalonyx, the only freshwater species examined, shows a gradual increase in spermatozoa that in the end completely fill the gonad (progressive maturation, tied to a semelparous life cycle). The testis in adult males of Amphibolus is either tilled exclusively with spermatozoa or alternatively with immature germinal cells, revealing an iteroparous condition similar to that of the females (cyclical maturation), The different types of gonad maturation in males seem to be correlated with habitat and the capacity to enter cryptobiosis.
1994
- New data on the nuclear DNA content in some species of tardigrades.
[Capitolo/Saggio]
Bertolani, Roberto; S., Garagna; Manicardi, Gian Carlo; Rebecchi, Lorena; C. A., Redi
abstract
In the chapter the Feulgen DNA content was evlauted in several species of tardigrades. A small genome size and poliploidy was confirmed.
1994
- Tardigrada
[Capitolo/Saggio]
Bertolani, Roberto
abstract
Asexual propagation is discussed in tardigrades. Mainly, parthenogeneis is considered in its various aspects: types, cytology, genetics, evolution. Life-history tactics hav also been considered.
1994
- Ulteriore contributo alla conoscenza dei Tardigradi di Marche e Umbria
[Articolo su rivista]
Bertolani, Roberto; Guidetti, Roberto; Rebecchi, Lorena
abstract
Studio sulla fauna tardigradologica di Marche ed Umbria. Identificazione di 26 specie una delle quali nuova per la scienza.
1993
- A NEW SPECIES OF RAMAZZOTTIUS (TARDIGRADA, HYPSIBIIDAE) IN A RAIN GUTTER SEDIMENT FROM ENGLAND
[Articolo su rivista]
Bertolani, Roberto; Kinchin, Im
abstract
Five species of tardigrades were extracted from a sample from a rain gutter. Four of these, the heterotardigrade Echiniscus testudo and the eutardigrades Milnesium tardigradum, Ramazzottius oberhaeuseri, and probably Macrobiotus cf. sandrae are typical of xerophilous habitats. The fifth species, Ramazzottius varieornatus sp. nov., is new to science, and it can be readly distinguished from the others of the same genus by egg shell morphology, placoids and the type of cuticle.
1993
- A revision of the Macrobiotus hufelandi group (Tardigrada, Macrobiotidae), with some observations on the taxonomic characters of eutardigrades.
[Articolo su rivista]
Bertolani, Roberto; Rebecchi, Lorena
abstract
This study considers specimens of Macrobiotus hufelandi C. A. S. Schultze, 1834 collected from Italy and Germany, including the type locality. In addition to a qualitative analysis of the animals and eggs, statistics were performed on the measurements of the sclerified parts of the animals. The data illustrate low intra-species variability in the morphology of both the animals and the eggs. Differences in egg shell morphology, previously attributed to the variability of M. hufelandi, were found to fall into distinct types, related to different animal morphotypes. The data also indicate that M. hufelandi contains several new species: M. macrocalix sp.n., M. sandrae sp.n. and M. terminalis sp.n.; M. hufelandi is redescribed, and a neotype is assigned.
1993
- Il ruolo della pedofauna nell'evoluzione della sostanza organica.
[Capitolo/Saggio]
Bertolani, Roberto; Sabatini, Maria Agnese
abstract
Vengono riportate le tecniche di campionamento dei vari componenti della pedofauna bei terreni coltivati e illustrato il ruolo della pedofauna nella decomposizione della sostanza organica del suolo.
1993
- Tardigradi dell’Appennino umbro-marchigiano
[Articolo su rivista]
Bertolani, Roberto; Guidetti, Roberto; Rebecchi, Lorena
abstract
Studio faunistico dei tardigradi di Marche ed Umbria. Identificazione di 32 specie di cui una nuova per la scienza.
1992
- Tardigrada.
[Capitolo/Saggio]
Bertolani, Roberto
abstract
Sexual differentiation is discussed in tardigrades. In particular sexual dimorphism is discussed, with some notes on the sexual behaviour. The presence of hermaphroditism in the phylum is pointed out.
1990
- DISPERSAL OF RAMAZZOTTIUS AND OTHER TARDIGRADES IN RELATION TO TYPE OF REPRODUCTION
[Articolo su rivista]
Bertolani, Roberto; Rebecchi, Lorena; Beccaccioli, G.
abstract
The relationships between the type of reproduction and sexuality and the types of substrates inhabited by semiterrestrial tardigrade populations are reported. Specimens of the genus Ramazzottius (Eutardigrada, Hypsibiidae) were collected from a limited area of hilly to mountainous zones near Modena and Reggio Emilia (Italy). The lichen substrate Xanthoria parietina, typically colonized by R. oberhaeuseri, was the main subject of study, though animals were also extracted from moss cushions. The sex ratio, correlated with the type of reproduction, clearly differed when the lichen or moss samples were collected from tree trunks or limited rocky areas, or came from extensive rocky outcrops. In the former case, the cytological characteristics of oocytes and the absence of males attest to thelytokous parthenogenesis. In the latter, some male specimens were always found, though several samples showed cytological evidence of parthenogenetic and amphimictic females. Differences in the distribution and frequency of the studied tardigrade strains which all utilize passive dispersal mechanisms, notwithstanding substrate and terrain homogeneity, are chiefly due to different modes of reproduction.
1990
- Tardigrada
[Capitolo/Saggio]
Bertolani, Roberto
abstract
The various modes of fertilization are discussed in tardigrades. The embryonic development is illustrated and postembryonic development considered. Some cases of parental care are descripted.
1989
- Cenni sul popolamento animale di alcune grotte del Complesso Carsico di S. Ninfa (Tp)
[Capitolo/Saggio]
Bertolani, Roberto; Manicardi, Gian Carlo
abstract
L'articolo descrive i dati relativi ad una campagna di raccolta di materiale biologico condotta in alcune grotte nei gessi dell'area carsica di S. Ninfa.
1989
- Effects of tillage practices on collembola populations
[Relazione in Atti di Convegno]
Bertolani, Roberto; Sabatini, Maria Agnese; Mola, Lucrezia
abstract
The data show that the positive effects on the population density of collembola of the change of ploughing with superficial tillage are not evident in the short time, but only in the long term. Thus , the substitution of ploughing with superficial tillage can produce a greater and more varied fauna and , consequently, a higher productivity of an agroecosystem.
1989
- Tardigradi e Gastrotrichi del Trentino: il Lago di Tovel.
[Articolo su rivista]
Bertolani, Roberto; Balsamo, Maria
abstract
Tardigrada and Gatrotricha from the Lake Tovel (Trentino, Italy) have been considered. The most interesting finding is represented by the finding of Isohypsibius baldii a species endemic from that lake. Some taxonomic details previously not described have been referred.
1988
- Effetti delle pratiche agronomiche sui microartropodi del terreno del suolo: l'aratura
[Poster]
Mola, Lucrezia; Manicardi, Gian Carlo; R., Lumetti; Sabatini, Maria Agnese; Bertolani, Roberto; P., Loro
abstract
sono stati messi a confronto due campi contigui arati in profondità per diversi anni; in uno di essi l'aratura profonda è stata sostituita con un 'aratura superficiel (10-15 cm). A 4 anni dalla sostituzione il numero sia degli acari che dei collemboli è significativamente maggiore nel campo arato solo superficialmente.
1988
- New cases of parthenogenesis and polyploidy in the genus Ramazzottius (Tardigrada, Hypsibiidae) and a hypothesis concerning their origin.
[Articolo su rivista]
Rebecchi, Lorena; Bertolani, Roberto
abstract
Specimens of the genus Ramazzottius Binda and Pilato 1986; were obtained from 2 moss and one lichen sample(s) collected in the Emilian Apennine Mountians. R. tribulosus was only found in one sample, whereas R. oberhaeuseri wa sfound in all three. The first species had only diploid specimens, with 6 bivalents during the first meiotic division; the second had only females showing various polyploid cytotypes in addition to the diploid bisexual cytotype cited for this area. One of the triploid and the tetraploid cytotyoes were charactetized by the presence of univalents at oocyte metaphase, Though the large number of cytotypes found in a single sample may be attributed to chance, it is better explained by an in loco origin, at least in soem cases.
1988
- Struttura delle unghie nei Macrobiotidae e descrizione di Murrayon n. gen. (Eutardigrada).
[Articolo su rivista]
Bertolani, Roberto; G., Pilato
abstract
The structure of the claws of the Macrobiotidae (Eutardigrada) has been critically reconsidered. On this basis a new genus, Murrayon, is erected.
1988
- The tardigrades of Emilia (Italy). I. Rossena.
[Articolo su rivista]
Bertolani, Roberto; Rebecchi, Lorena
abstract
The following species are found in a moss collected at Rossena (Reggio Emilia, Italy): Cornechinioscus lobatus, Echinicus trisetosus, Macrobiotus csotiensis, M. areolatus, M. cf. hufelandi, Doryphoribius flavus, Ramazzottius oberhaeuseri and a new species, Ramazzottius tribulosus, very similar to R. oberhaeuseri, but clearly dostinguishable by its cone -shaped egg processes.
1987
- Biology of Tardigrades
[Monografia/Trattato scientifico]
Bertolani, Roberto
abstract
Various contributions on tardigrade morphology, physiology, histochemistry and biochemistry, reproductive biology, ecology and taxonomy are referred.
1987
- Effects of atrazine on two species of Collembola (Onychiuridae) in laboratory tests.
[Articolo su rivista]
Mola, Lucrezia; Sabatini, Maria Agnese; Fratello, Bernardo; Bertolani, Roberto
abstract
Laboratory tests were performed to investigate the effects on Onychiurus armatus (Tullberg) and O. apuanicus Dallai of the herbicide atrazine at serial concentrations of 2.5 to 160 ppm. In O. apuanicus the lowest doses caused a mortality of 18.7 % after 30 days and 46.7% after 60 days. The 2 species showed different sensitivity to atrazine, especially at the higher doses. The LD50 after 30 days was 17.2 ppm for O. apuanicus and 20 ppm for O. armatus. Oviposition does not occur at 20 ppm or greater, whereas at lower doses no effects were found on reproduction.
1987
- First contribution to the knowledge of alpine grassland tardigrades.
[Capitolo/Saggio]
Manicardi, Gian Carlo; Bertolani, Roberto
abstract
The paper describes the composition of tardigrades fauna in alpine grasslands.
1987
- Tardigradi della Riserva Naturale del Torricchio e dei Monti Sibillini.
[Capitolo/Saggio]
Bertolani, Roberto; Manicardi, Gian Carlo; Gibertoni, D.
abstract
L'articolo presenta i risultati di una ricerca faunistica relativa allo studio della Tardigradofauna della Riserva Naturale del Torricchio e dei Monti Sibillini.
1986
- Effects of the herbicide atrazine on Collembola
[Relazione in Atti di Convegno]
Fratello, Bernardo; Bertolani, Roberto; Sabatini, Maria Agnese; Mola, Lucrezia
abstract
Vengono esposti i risultti ottenuti sia da ricerche in campo che da test di laboratorio condotte per valutare gli effetti dell'erbicida atrazina suli Collmboli
1986
- New cases of hermaphroditism in tardigrades.
[Articolo su rivista]
Bertolani, Roberto; Manicardi, Gian Carlo
abstract
The paper describes evidences of hermaphdroditic reproduction in some tardigrades.
1985
- Effects of atrazine on soil microarthropods in experimental maize fields.
[Articolo su rivista]
Fratello, Bernardo; Bertolani, Roberto; Sabatini, Maria Agnese; Mola, Lucrezia; Rassu, M. A.
abstract
Atrazine treatment of experimental fields cultivated with maize may or may not cause significant decreases in microarthropod populations living in the 0-10cm layer. Immediate negative effects on Acarina and Collembola population density were found in one field and no effects in another. In the first field atrazine had only very limited or nil effects on soil microarthropod populations at the recommended agricultural dose of 2 kg /ha treated plot, any negative effects were followed by a recovery one month from treatment. The microarthropods living below 10 cm depth never showed any significant reduction in numbers.
1984
- Postembryonic development in heterotardigrades.
[Articolo su rivista]
Bertolani, Roberto; S., Grimaldi de Zio; M., D'Addabbo Gallo; M. R., Morone De Lucia
abstract
Some heterotardigrades, both marine and terrestrial, have been considered from a postembryonic development point of view. A common situation has been found, i.e. the first instar is characterized by the absence of both anus and gonopore (and by a reduced number of claws), a second instar by the absence only of gonopore. This situation differs from that of eutardigrades, where there is a direct development.
1983
- Macrobiotus joannae, primo Macrobiotidae ermafrodito (Eutardigrada).
[Articolo su rivista]
Bertolani, Roberto; G., Pilato; Sabatini, Maria Agnese
abstract
Viene segnalato il primo caso di specie ermafrodita nella famiglia Macrobiotidae. Come negli altri casi accertati, anche macrobiotus joannae è provvisto di ovotestis. Oltre che nei Macrobiotidae, altre specie ermafrodite sono state riscontrate nella famiglia Hypsibiidae e, probabilmente, Amphibolidae (tutti Eutardigradi).
1983
- Studio degli Isohypsibius del gruppo elegans (Eutardigrada, Hypsibiidae) con descrizione di due nuove specie.
[Articolo su rivista]
G., Pilato; Bertolani, Roberto; M. G., Binda
abstract
Some species of eutardigrades from moss and freshwater have been studied from a taxonomical point of view, using both qualitative and quantitative characters. They belong to a so called "Isohypsibius elegans" group. A new species is described and a subspecies has been moved to species rank.
1983
- Tardigrada
[Capitolo/Saggio]
Bertolani, Roberto
abstract
The various steps of the permatogenesis and the sperm structure and ultrastructure are comparatively considered in tardigrades.
1983
- Tardigrada
[Capitolo/Saggio]
Bertolani, Roberto
abstract
The processes of the ogenesis, the structure and ultrastructure of the eggs and the various ways of oviposition are descripted in tardigrades.
1982
- Effetti diretti e indiretti di un erbicida sui microartropodi del suolo: studi in laboratorio
[Abstract in Rivista]
Mola, Lucrezia; Sabatini, Maria Agnese; B., Fratello; M. A., Rassu; Bertolani, Roberto
abstract
Collemboli di due specie affini (Onychiurus armatus e O. apuanicus) allevati in laboratorio, sono stati esposti per 30 e per 60 ggiorni a varie dosi di atrazina, in terreni di sabbia silicea sterilizzata. I risultati riguardo la mortalità e la fecondità hanno indicato che la sensibilità all'erbicida è specie-specifica.
1982
- Effetti diretti e indiretti di un erbicida sui microartropodi del suolo: studi su terreni agrari.
[Abstract in Rivista]
B., Fratello; Bertolani, Roberto; Sabatini, Maria Agnese; M. A., Rassu; Mola, Lucrezia
abstract
L'effetto dell'atrazina è stato valutato esaminando la popolazione di acari e collemboli in campi sperimentali trattati con tale erbicida. L'effetto è diverso per le diverse famiglie di colleemboli, e in qualche caso anche per le diverse specie.
1982
- Tardigradi (Tardigrada)
[Monografia/Trattato scientifico]
Bertolani, Roberto
abstract
Vengono descritte e raffigurate tutte le specie di tardigradi rinvenute nelle acque interne italiane. La descrizione è precedeuta da cenni generali sulla biologia dei tardigradi, sulle tecniche di campionamento e sui caratteri tassonomici da utilizzare.
1981
- A new genus and five new species of Italian freshwater tardigrades.
[Articolo su rivista]
Bertolani, Roberto
abstract
Five new species of freshwater eutardigrades are described. They belong to the Italian limnetic fauna and some of them have been found in areas not yet studied to date from a tardigradological point of view.
1981
- Metodi per la rilevazione degli effetti dell'atrazina ed altri erbicidi sulla pedofauna.
[Capitolo/Saggio]
Bertolani, Roberto; Sabatini, Maria Agnese; Fratello, B.
abstract
Vengono presentati metodi per la valutazione degli effetti sulla pedofauna di erbicidi con particolare riguardo all'atrazina. Vengono prese in considerazione prove in laboratorio e prove in campo.
1981
- Osservazioni istologiche e istochimiche sul differenziamento della cute in esemplari metamorfosati e non di Triturus alpestris apuanus (Bonap) (Amphibia Urodela)
[Articolo su rivista]
Mola, Lucrezia; Bertolani, Roberto
abstract
E' stato condotto uno studio istologico ed istochimico sulla pelle di esemplari larvali, metamorfosati e neotenici di Triturus alpestris. Nei metamorfosati sono presenti due tipi di ghiandole granulose, uno dei quali, per le positività ad alcune reazioni istochimiche, sembra contenere granuli di 5-idrossitriptamina, dato nuovo per gli Urodeli.
1981
- The taxonomic position of some eutardigrades.
[Articolo su rivista]
Bertolani, Roberto
abstract
Some tardigrade species attributed to the genus Isohypsibius are reconsidered from a taxonomic point of view. Some characters look peculiar, therefore a new genus, Amphibolus, is erected for these species.
1979
- Hermaphroditism in tardigrades.
[Articolo su rivista]
Bertolani, Roberto
abstract
The first case of a hermaphroditic population in tardigrades is described.
1979
- Il popolamento dei microartropodi in terreni trattati con atrazina
[Relazione in Atti di Convegno]
Bertolani, Roberto; Sabatini, Maria Agnese; . B., Fratello
abstract
L'effetto del trattamento con differenti dosi dell'erbicida atrazina è stato studiato in tre campi sperimentali. I tre campi, tutti coltivati a mais e trattati in parte con atrazina, si diversificavano per aver subito in precedenza differenti trattamenti e per la collocazione geografica. Effetti dell'atrazina sui microartropodi sono sono stati evidenziati solo nel campo che negli anni precedenti a quello del prelievo non era mai stato sottoposto al trattamento con l'erbicida.
1979
- Microarthropod communities in soil treated with atrazine
[Articolo su rivista]
Sabatini, Maria Agnese; B., Fratello; Bertolani, Roberto; Pederzoli, Aurora
abstract
The effects of atrazine on soil microarthropod populations was studied in an experimental field cultivated with maize. Three doses of herbicide (2,4, 6 Kg/ha) were tested in three different periods and on four layers. Controls were employed. Collembola and Oribatid mites were studied at species-level. The number of microarthropod specimens in the treated plots was not significantly different from that in the control plots.
1977
- Analisi cariologica e morfologica di alcune popolazioni di Macrobiotus hufelandi (Tardigrada) della Valsesia.
[Articolo su rivista]
Bertolani, Roberto; V., Mambrini
abstract
Four populations with a different sex ratio of the tardigrade Macrobiotus hufelandi are recognized in an alpine valley. This difference is due to the presence of three biotypes (diploid, triploid and tetraploid biotype). Ameiotic thelitokous parthenogenesis is present in the triploid and tetraploid biotypes, while the diploid biotype is bisexual. Two types of eggs, probably related to the biotypes, are identified by morphological abalysis of the egg shell.
1976
- Osservazioni cariologiche su Isohypsibius augusti (Murray, 1907) e I. megalonyx Thulin, 1928 (Tardigrada) e ridescrizione delle due specie.
[Articolo su rivista]
Bertolani, Roberto
abstract
Organismi attribuiti dal punto di vista morfologico alla stessa specie sono stati esaminati sia dal punto di vista cariologico, sia da quello morfologico. E' emerso che due specie poste in passato in sinonimia avevano in realà numeri cromosomici diversi ed anche differenze tassonomiche rilevabili. Una delle due, inoltre, era caratterizzata sia da indivudui diploidi con maschi e femmine, che da femmine triploidi.
1975
- Cytology and Systematics in Tardigrada.
[Relazione in Atti di Convegno]
Bertolani, Roberto
abstract
Vengono riportati i primi risultati sullo studio della cariologia dei tardigradi e sugli aspetti della maturazione delle uova partenogenetiche in questo phylum.
1975
- Osservazioni cariologiche sulla partenogenesi meiotica di Macrobiotus dispar (Tardigrada).
[Articolo su rivista]
Bertolani, Roberto; G. P., Guonagurelli
abstract
Having found no males during three years of breeding in Macrobiotus dispar the parthenogenesis has been demostrated. The karyological examination has shown that M. dispar has a diploid meiotic and chiasmatic parthenogenesis and the restitutive process takes place at the beginning of the 2nd oocyte division.
1974
- Primo caso di una popolazione tetraploide nei Tardigradi
[Articolo su rivista]
Bertolani, Roberto
abstract
A population of Hypsibius oberhaeuseri without males(4n = 14) was found near Trento, Italy. The karyologic examination of verified that the population belongs to a tetraploid biotype riproducing by an ameiotic parthenogenesis. Some quantitative inquiries about this tetraploid biotype and the two others already known (diploid and triploid) indicate that the somatic size increases with the ploidy degree. The presence of three biotypes in H. oberhaeuseri demostrates that some species of Tardigrada have a high level of complexity.
1973
- Presenza di un biotipo partenogenetico e suo effetto sul rapporto-sessi in Macrobiotus hufelansi (Tardigrada).
[Articolo su rivista]
Bertolani, Roberto
abstract
In samples of M. hufelandi found near Andalo (Trento) the sex ratio changes in different places of the same rock (from 1:1 to 1:4). The karyological analysis evidences that two populations attributable to the same species can be present in the same site, one being bisexual and diploid and the other thelytocous and triploid.
1972
- La partenogenesi nei Tardigradi.
[Articolo su rivista]
Bertolani, Roberto
abstract
Sono analizzati diversi casi di partenogenesi nei tardigradi, tutti relativi a specie delle quali sono state trovate popolazioni anfimittiche.
1972
- Osservazioni cariologiche su alcuni Macrobiotus (Tardigrada).
[Articolo su rivista]
Bertolani, Roberto
abstract
The chromosome morphology and number in somatic and germinal cells were studied in some species of Macrobiotus. Most of these species ((M. areolatus, M. coronifer, M. harmsworthi, M. hufelandi, and the bisexual biotype of M. richtersi) have 2n = 12 chromosomes, but in two freswater species with similar morphology (M. dispar and M. pullari) 2n = 10 chromosomes are found. The chromosome number in males and females of M. areolatus and M. richtersi is the same. In the ripening oocytes and in the first blastomeres the metaphasic chromosomes show a peculiar large size. No idiograms were made because the chromosomes are too small, similar and without detectable centromeres.
1971
- Contributo alla cariologia dei Tardigradi. Osservazioni su Macrobiotus hufelandii.
[Articolo su rivista]
Bertolani, Roberto
abstract
The chromosome number in Macrobiotus hufelandi is 2n = 12 and n = 6 as in two other species of Macrobiotus (M. richtersi from Pisa and M. harmsworthi). The results differ from previous data which have stated 2n = 14 in M. hufelandi females. It is supposed that at least two sibling species are included in M. hufelandi.
1971
- Osservazioni cariologiche su biotipi bisessuati e partenogenetici di Hypsibius oberhaeuseri (Tardigrada).
[Articolo su rivista]
Bertolani, Roberto
abstract
Bisexual and unisexual (without males) biotypes are found in the tardigrade Hypsibius oberhaeuseri. The karyological analysis shows a chromosome number 2 = 12 and n = 6 in the bisexual biotype, while in the biotype without males there are 18 chromosomes in the mitosis and 18 univalents in the maturative division. Therefore a biotype of H. oberhaeuseri is triploid with an ameiotic parthenogenesia.
1971
- Partenogenesi geografica triploide in un Tardigrado.
[Articolo su rivista]
Bertolani, Roberto
abstract
In a bisexual population of Macrobiotus richtersi from Pisa the chromosome set is 2n = 12 and n = 6. It is also shown that in the same species, but in a different geographical territory (Modena), is present a prthenogenetic triploid (3n = 18) biotype. This kind of parthenogenesis is ameiotic. In the organs of the triploid individuals the number of cells is similar to that of the diploid population.
1971
- Rapporto-sessi e dimorfismo sessuale in Macrobiotus
[Articolo su rivista]
Bertolani, Roberto
abstract
In four species of Macrobiotus (M. areolatus, M. hufelandi, M. intermedius and M. richtersi) with bisexual populations the sex ratio is about 1:1. In two of these species (M. hufelandi and M. richtersi) were found some samples without males, probably parthenogenetic. The bisexual populations of Macrobiotus show a sexual dimorphism, females being bigger than male animals.
1971
- Sex Ratio and Geographic Parthenogenesis in Macrobiotus (Tardigrada)
[Articolo su rivista]
Bertolani, Roberto
abstract
A comparison between an amphimictic and a prthenogenetic population of Macrobiotus richtersi is carried out, with evaluation their geographic distribution.
1970
- Mitosi somatiche e costanza cellulare numerica nei Tardigradi
[Articolo su rivista]
Bertolani, Roberto
abstract
Somatic mitoses have been observed in the adults of three species of Macrobiotus. The frequency of animals with somatic mitoses does not vary with the species, but it changes in relationship to the moulting and the season. Therefore, tardigrades do not have a constant cell number.
1970
- Variabilità numerica cellulare in alcuni tessuti di tardigradi.
[Articolo su rivista]
Bertolani, Roberto
abstract
In tardigrades the number of the storage cells, of the cells of the Malpighian tubules and of the 3rd ventral ganglion, varies. In the last case the swinging of the cell number, being not related to the growth, is due to a renewal of cells. Therefore tardigrades do not have a constant cell number in spite of a trend towards a secondary numerical constancy of some tissues, e. g. of the nervous tissue.