Tardigrades as a Potential Model Organism in Space Research

NASA Astrophysics Data System (ADS)

Jönsson, K. Ingemar

2007-10-01

Exposure of living organisms to open space requires a high level of tolerance to desiccation, cold, and radiation. Among animals, only anhydrobiotic species can fulfill these requirements. The invertebrate phylum Tardigrada includes many anhydrobiotic species, which are adapted to survive in very dry or cold environmental conditions. As a likely by-product of the adaptations for desiccation and freezing, tardigrades also show a very high tolerance to a number of other, unnatural conditions, including exposure to ionizing radiation. This makes tardigrades an interesting candidate for experimental exposure to open space. This paper reviews the tolerances that make tardigrades suitable for astrobiological studies and the reported radiation tolerance in other anhydrobiotic animals. Several studies have shown that tardigrades can survive γ-irradiation well above 1 kilogray, and desiccated and hydrated (active) tardigrades respond similarly to irradiation. Thus, tolerance is not restricted to the dry anhydrobiotic state, and I discuss the possible involvement of an efficient, but yet undocumented, mechanism for DNA repair. Other anhydrobiotic animals (Artemia, Polypedium), when dessicated, show a higher tolerance to γ-irradiation than hydrated animals, possibly due to the presence of high levels of the protective disaccharide trehalose in the dry state. Tardigrades and other anhydrobiotic animals provide a unique opportunity to study the effects of space exposure on metabolically inactive but vital metazoans.

Tardigrades as a potential model organism in space research.

PubMed

Jönsson, K Ingemar

2007-10-01

Exposure of living organisms to open space requires a high level of tolerance to desiccation, cold, and radiation. Among animals, only anhydrobiotic species can fulfill these requirements. The invertebrate phylum Tardigrada includes many anhydrobiotic species, which are adapted to survive in very dry or cold environmental conditions. As a likely by-product of the adaptations for desiccation and freezing, tardigrades also show a very high tolerance to a number of other, unnatural conditions, including exposure to ionizing radiation. This makes tardigrades an interesting candidate for experimental exposure to open space. This paper reviews the tolerances that make tardigrades suitable for astrobiological studies and the reported radiation tolerance in other anhydrobiotic animals. Several studies have shown that tardigrades can survive gamma-irradiation well above 1 kilogray, and desiccated and hydrated (active) tardigrades respond similarly to irradiation. Thus, tolerance is not restricted to the dry anhydrobiotic state, and I discuss the possible involvement of an efficient, but yet undocumented, mechanism for DNA repair. Other anhydrobiotic animals (Artemia, Polypedium), when dessicated, show a higher tolerance to gamma-irradiation than hydrated animals, possibly due to the presence of high levels of the protective disaccharide trehalose in the dry state. Tardigrades and other anhydrobiotic animals provide a unique opportunity to study the effects of space exposure on metabolically inactive but vital metazoans.

Astrobiological Research on Tardigrades: Implications for Extraterrestrial Life Forms

NASA Astrophysics Data System (ADS)

Horikawa, D. D.

2013-11-01

Tardigrades have been considered as a model for astrobiological studies based on their tolerance to extreme environments. Future research on tardigrades might provide important insight into the possibilities of existence of multicellular life forms.

Neural Markers Reveal a One-Segmented Head in Tardigrades (Water Bears)

PubMed Central

Mayer, Georg; Kauschke, Susann; Rüdiger, Jan; Stevenson, Paul A.

2013-01-01

Background While recent neuroanatomical and gene expression studies have clarified the alignment of cephalic segments in arthropods and onychophorans, the identity of head segments in tardigrades remains controversial. In particular, it is unclear whether the tardigrade head and its enclosed brain comprises one, or several segments, or a non-segmental structure. To clarify this, we applied a variety of histochemical and immunocytochemical markers to specimens of the tardigrade Macrobiotus cf. harmsworthi and the onychophoran Euperipatoides rowelli. Methodology/Principal Findings Our immunolabelling against serotonin, FMRFamide and α-tubulin reveals that the tardigrade brain is a dorsal, bilaterally symmetric structure that resembles the brain of onychophorans and arthropods rather than a circumoesophageal ring typical of cycloneuralians (nematodes and allies). A suboesophageal ganglion is clearly lacking. Our data further reveal a hitherto unknown, unpaired stomatogastric ganglion in Macrobiotus cf. harmsworthi, which innervates the ectodermal oesophagus and the endodermal midgut and is associated with the second leg-bearing segment. In contrast, the oesophagus of the onychophoran E. rowelli possesses no immunoreactive neurons, whereas scattered bipolar, serotonin-like immunoreactive cell bodies are found in the midgut wall. Furthermore, our results show that the onychophoran pharynx is innervated by a medullary loop nerve accompanied by monopolar, serotonin-like immunoreactive cell bodies. Conclusions/Significance A comparison of the nervous system innervating the foregut and midgut structures in tardigrades and onychophorans to that of arthropods indicates that the stomatogastric ganglion is a potential synapomorphy of Tardigrada and Arthropoda. Its association with the second leg-bearing segment in tardigrades suggests that the second trunk ganglion is a homologue of the arthropod tritocerebrum, whereas the first ganglion corresponds to the deutocerebrum. We

Neural markers reveal a one-segmented head in tardigrades (water bears).

PubMed

Mayer, Georg; Kauschke, Susann; Rüdiger, Jan; Stevenson, Paul A

2013-01-01

While recent neuroanatomical and gene expression studies have clarified the alignment of cephalic segments in arthropods and onychophorans, the identity of head segments in tardigrades remains controversial. In particular, it is unclear whether the tardigrade head and its enclosed brain comprises one, or several segments, or a non-segmental structure. To clarify this, we applied a variety of histochemical and immunocytochemical markers to specimens of the tardigrade Macrobiotus cf. harmsworthi and the onychophoran Euperipatoides rowelli. Our immunolabelling against serotonin, FMRFamide and α-tubulin reveals that the tardigrade brain is a dorsal, bilaterally symmetric structure that resembles the brain of onychophorans and arthropods rather than a circumoesophageal ring typical of cycloneuralians (nematodes and allies). A suboesophageal ganglion is clearly lacking. Our data further reveal a hitherto unknown, unpaired stomatogastric ganglion in Macrobiotus cf. harmsworthi, which innervates the ectodermal oesophagus and the endodermal midgut and is associated with the second leg-bearing segment. In contrast, the oesophagus of the onychophoran E. rowelli possesses no immunoreactive neurons, whereas scattered bipolar, serotonin-like immunoreactive cell bodies are found in the midgut wall. Furthermore, our results show that the onychophoran pharynx is innervated by a medullary loop nerve accompanied by monopolar, serotonin-like immunoreactive cell bodies. A comparison of the nervous system innervating the foregut and midgut structures in tardigrades and onychophorans to that of arthropods indicates that the stomatogastric ganglion is a potential synapomorphy of Tardigrada and Arthropoda. Its association with the second leg-bearing segment in tardigrades suggests that the second trunk ganglion is a homologue of the arthropod tritocerebrum, whereas the first ganglion corresponds to the deutocerebrum. We therefore conclude that the tardigrade brain consists of a single

Novel origin of lamin-derived cytoplasmic intermediate filaments in tardigrades.

PubMed

Hering, Lars; Bouameur, Jamal-Eddine; Reichelt, Julian; Magin, Thomas M; Mayer, Georg

2016-02-03

Intermediate filament (IF) proteins, including nuclear lamins and cytoplasmic IF proteins, are essential cytoskeletal components of bilaterian cells. Despite their important role in protecting tissues against mechanical force, no cytoplasmic IF proteins have been convincingly identified in arthropods. Here we show that the ancestral cytoplasmic IF protein gene was lost in the entire panarthropod (onychophoran + tardigrade + arthropod) rather than arthropod lineage and that nuclear, lamin-derived proteins instead acquired new cytoplasmic roles at least three times independently in collembolans, copepods, and tardigrades. Transcriptomic and genomic data revealed three IF protein genes in the tardigrade Hypsibius dujardini, one of which (cytotardin) occurs exclusively in the cytoplasm of epidermal and foregut epithelia, where it forms belt-like filaments around each epithelial cell. These results suggest that a lamin derivative has been co-opted to enhance tissue stability in tardigrades, a function otherwise served by cytoplasmic IF proteins in all other bilaterians.

Diapause in tardigrades: a study of factors involved in encystment.

PubMed

Guidetti, Roberto; Boschini, Deborah; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena

2008-07-01

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 well studied, while little attention has been devoted to the adaptive meaning of encystment (diapause). Our goal was to determine the environmental factors and token stimuli involved in the encystment process of tardigrades. The eutardigrade Amphibolus volubilis, a species able to produce two types of cyst (type 1 and type 2), was considered. Laboratory experiments and long-term studies on cyst dynamics of a natural population were conducted. Laboratory experiments demonstrated 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. The 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 are present during the cold season. Temperature represents the environmental factor involved in induction, maintenance and termination of the cyst. We also obtained evidence 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.

Ground Testing of the EMCS Seed Cassette for Biocompatibility with the Tardigrade, Hypsibius dujardini

NASA Technical Reports Server (NTRS)

Reinsch, Sigrid; Myers, Zachary Alan; DeSimone, Julia Carol; Freeman, John L.; Steele, Marianne K.; Sun, Gwo-Shing; Heathcote, David

2014-01-01

The European Modular Cultivation System, EMCS, was developed by ESA for plant experiments. We performed ground testing to determine whether ARC EMCS seed cassettes could be adapted for use with tardigrades for future spaceflight experiments. Tardigrades (water bears) are small invertebrates that enter the tun state in response to desiccation or other environmental stresses. Tardigrade tuns have suspended metabolism and have been shown to be survive exposure to space vacuum, high pressure, temperature and other stresses. For spaceflight experiments using the EMCS, the organisms ideally must be able to survive desiccation and storage in the cassette at ambient temperature for several weeks prior to the initiation of the experiment by the infusion of water to the cassette during spaceflight. The ability of tardigrades to survive extremes by entering the tun state make them ideal candidates for growth experiments in the EMCS cassettes. The growth substratum in the cassettes is a gridded polyether sulfone (PES) membrane. A blotter beneath the PES membrane contains dried growth medium. The goals of our study were to (1) determine whether tardigrades survive and reproduce on PES membranes, (2) develop a consistent method for dehydration of the tardigrades with high recovery rates upon rehydration, (3) to determine an appropriate food source for the tardigrades that can also be dehydrated/rehydrated and (4) successful mock rehydration experiment in cassettes with appropriate food source. We present results that show successful multigenerational growth of tardigrades on PES membranes with a variety of wet food sources. We have successfully performed a mock rehydration with tardigrades and at least one candidate food, protonema of the moss Polytrichum, that supports multigenerational growth and whose spores germinate quickly enough to match tardigrade feeding patterns post rehydration. Our results indicate that experiments on the ISS using the tardigrade, Hypsibius dujardini

Neural development in the tardigrade Hypsibius dujardini based on anti-acetylated α-tubulin immunolabeling.

PubMed

Gross, Vladimir; Mayer, Georg

2015-01-01

The tardigrades (water bears) are a cosmopolitan group of microscopic ecdysozoans found in a variety of aquatic and temporarily wet environments. They are members of the Panarthropoda (Tardigrada + Onychophora + Arthropoda), although their exact position within this group remains contested. Studies of embryonic development in tardigrades have been scarce and have yielded contradictory data. Therefore, we investigated the development of the nervous system in embryos of the tardigrade Hypsibius dujardini using immunohistochemical techniques in conjunction with confocal laser scanning microscopy in an effort to gain insight into the evolution of the nervous system in panarthropods. An antiserum against acetylated α-tubulin was used to visualize the axonal processes and general neuroanatomy in whole-mount embryos of the eutardigrade H. dujardini. Our data reveal that the tardigrade nervous system develops in an anterior-to-posterior gradient, beginning with the neural structures of the head. The brain develops as a dorsal, bilaterally symmetric structure and contains a single developing central neuropil. The stomodeal nervous system develops separately and includes at least four separate, ring-like commissures. A circumbuccal nerve ring arises late in development and innervates the circumoral sensory field. The segmental trunk ganglia likewise arise from anterior to posterior and establish links with each other via individual pioneering axons. Each hemiganglion is associated with a number of peripheral nerves, including a pair of leg nerves and a branched, dorsolateral nerve. The revealed pattern of brain development supports a single-segmented brain in tardigrades and challenges previous assignments of homology between tardigrade brain lobes and arthropod brain segments. Likewise, the tardigrade circumbuccal nerve ring cannot be homologized with the arthropod 'circumoral' nerve ring, suggesting that this structure is unique to tardigrades. Finally, we propose

Novel origin of lamin-derived cytoplasmic intermediate filaments in tardigrades

PubMed Central

Hering, Lars; Bouameur, Jamal-Eddine; Reichelt, Julian; Magin, Thomas M; Mayer, Georg

2016-01-01

Intermediate filament (IF) proteins, including nuclear lamins and cytoplasmic IF proteins, are essential cytoskeletal components of bilaterian cells. Despite their important role in protecting tissues against mechanical force, no cytoplasmic IF proteins have been convincingly identified in arthropods. Here we show that the ancestral cytoplasmic IF protein gene was lost in the entire panarthropod (onychophoran + tardigrade + arthropod) rather than arthropod lineage and that nuclear, lamin-derived proteins instead acquired new cytoplasmic roles at least three times independently in collembolans, copepods, and tardigrades. Transcriptomic and genomic data revealed three IF protein genes in the tardigrade Hypsibius dujardini, one of which (cytotardin) occurs exclusively in the cytoplasm of epidermal and foregut epithelia, where it forms belt-like filaments around each epithelial cell. These results suggest that a lamin derivative has been co-opted to enhance tissue stability in tardigrades, a function otherwise served by cytoplasmic IF proteins in all other bilaterians. DOI: http://dx.doi.org/10.7554/eLife.11117.001 PMID:26840051

Tardigrades in Space Research - Past and Future.

PubMed

Weronika, Erdmann; Łukasz, Kaczmarek

2017-12-01

To survive exposure to space conditions, organisms should have certain characteristics including a high tolerance for freezing, radiation and desiccation. The organisms with the best chance for survival under such conditions are extremophiles, like some species of Bacteria and Archea, Rotifera, several species of Nematoda, some of the arthropods and Tardigrada (water bears). There is no denying that tardigrades are one of the toughest animals on our planet and are the most unique in the extremophiles group. Tardigrada are very small animals (50 to 2,100 μm in length), and they inhabit great number of Earth environments. Ever since it was proven that tardigrades have high resistance to the different kinds of stress factors associated with cosmic journeys, combined with their relatively complex structure and their relative ease of observation, they have become a perfect model organism for space research. This taxon is now the focus of astrobiologists from around the world. Therefore, this paper presents a short review of the space research performed on tardigrades as well as some considerations for further studies.

Tardigrades in Space Research - Past and Future

NASA Astrophysics Data System (ADS)

Weronika, Erdmann; Łukasz, Kaczmarek

2017-12-01

To survive exposure to space conditions, organisms should have certain characteristics including a high tolerance for freezing, radiation and desiccation. The organisms with the best chance for survival under such conditions are extremophiles, like some species of Bacteria and Archea, Rotifera, several species of Nematoda, some of the arthropods and Tardigrada (water bears). There is no denying that tardigrades are one of the toughest animals on our planet and are the most unique in the extremophiles group. Tardigrada are very small animals (50 to 2,100 μm in length), and they inhabit great number of Earth environments. Ever since it was proven that tardigrades have high resistance to the different kinds of stress factors associated with cosmic journeys, combined with their relatively complex structure and their relative ease of observation, they have become a perfect model organism for space research. This taxon is now the focus of astrobiologists from around the world. Therefore, this paper presents a short review of the space research performed on tardigrades as well as some considerations for further studies.

The Moss Fauna 1: Tardigrades.

ERIC Educational Resources Information Center

Kinchin, Ian M.

1987-01-01

Describes the Tardigrada as a group of animals suitable for close study in project work. Gives reasons for their suitability and an illustrated identification key. Discusses possible investigations into the ecology and physiology of tardigrades. (Author/CW)

Survival in extreme environments - on the current knowledge of adaptations in tardigrades.

PubMed

Møbjerg, N; Halberg, K A; Jørgensen, A; Persson, D; Bjørn, M; Ramløv, H; Kristensen, R M

2011-07-01

Tardigrades are microscopic animals found worldwide in aquatic as well as terrestrial ecosystems. They belong to the invertebrate superclade Ecdysozoa, as do the two major invertebrate model organisms: Caenorhabditis elegans and Drosophila melanogaster. We present a brief description of the tardigrades and highlight species that are currently used as models for physiological and molecular investigations. Tardigrades are uniquely adapted to a range of environmental extremes. Cryptobiosis, currently referred to as a reversible ametabolic state induced by e.g. desiccation, is common especially among limno-terrestrial species. It has been shown that the entry and exit of cryptobiosis may involve synthesis of bioprotectants in the form of selective carbohydrates and proteins as well as high levels of antioxidant enzymes and other free radical scavengers. However, at present a general scheme of mechanisms explaining this phenomenon is lacking. Importantly, recent research has shown that tardigrades even in their active states may be extremely tolerant to environmental stress, handling extreme levels of ionizing radiation, large fluctuation in external salinity and avoiding freezing by supercooling to below -20 °C, presumably relying on efficient DNA repair mechanisms and osmoregulation. This review summarizes the current knowledge on adaptations found among tardigrades, and presents new data on tardigrade cell numbers and osmoregulation. © 2011 The Authors. Acta Physiologica © 2011 Scandinavian Physiological Society.

Anhydrobiosis in tardigrades--the last decade.

PubMed

Wełnicz, Weronika; Grohme, Markus A; Kaczmarek, Lukasz; Schill, Ralph O; Frohme, Marcus

2011-05-01

The current state of knowledge about anhydrobiosis in tardigrades is presented. In response to adverse environmental conditions tardigrades arrest their metabolic activity and after complete dehydration enter the so-called "tun" state. In this ametabolic state they are able to tolerate exposure to various chemical and physical extremes. These micrometazoans have evolved various kinds of morphological, physiological and molecular adaptations to reduce the effects of desiccation. In this review we address behavioral adaptation, morphological features and molecules which determine the anhydrobiotic survival. The influence of the time spent in anhydrobiotic state on the lifespan and DNA and the role of the antioxidant defense system are also considered. Finally we summarize recent input from the "omics" sciences. Copyright © 2011 Elsevier Ltd. All rights reserved.

Experimentally induced anhydrobiosis in the tardigrade Richtersius coronifer: phenotypic factors affecting survival.

PubMed

Jönsson, K Ingemar; Rebecchi, Lorena

2002-11-01

The ability of some animal taxa (e.g., nematodes, rotifers, and tardigrades) to enter an ametabolic (cryptobiotic) state is well known. Nevertheless, the phenotypic factors affecting successful anhydrobiosis have rarely been investigated. We report a laboratory study on the effects of body size, reproductive condition, and energetic condition on anhydrobiotic survival in a population of the eutardigrade Richtersius coronifer. Body size and energetic condition interacted in affecting the probability of survival, while reproductive condition had no effect. Large tardigrades had a lower probability of survival than medium-sized tardigrades and showed a positive response in survival to energetic condition. This suggests that energy constrained the possibility for large tardigrades to enter and to leave anhydrobiosis. As a possible alternative explanation for low survival in the largest specimens we discuss the expression of senescence. In line with the view that processes related to anhydrobiosis are connected with energetic costs we documented a decrease in the size of storage cells over a period of anhydrobiosis, showing for the first time that energy is consumed in the process of anhydrobiosis in tardigrades. Copyright 2002 Wiley-Liss, Inc.

The Microbial Community of Tardigrades: Environmental Influence and Species Specificity of Microbiome Structure and Composition.

PubMed

Vecchi, Matteo; Newton, Irene L G; Cesari, Michele; Rebecchi, Lorena; Guidetti, Roberto

2018-01-15

Symbiotic associations of metazoans with bacteria strongly influence animal biology since bacteria are ubiquitous and virtually no animal is completely free from them. Tardigrades are micrometazoans famous for their ability to undergo ametabolic states (cryptobiosis) but very little information is available on potential microbial associations. We characterized the microbiomes of six limnoterrestrial tardigrade species belonging to several phylogenetic lines in tandem with the microbiomes of their respective substrates. The experimental design enabled us to determine the effects of both the environment and the host genetic background on the tardigrade microbiome; we were able to define the microbial community of the same species sampled from different environments, and the communities of different species from the same environment. Our 16S rRNA gene amplicon approach indicated that the tardigrade microbiome is species-specific and well differentiated from the environment. Tardigrade species showed a much lower microbial diversity compared to their substrates, with only one significant exception. Forty-nine common OTUs (operational taxonomic units) were classified into six bacterial phyla, while four common OTUs were unclassified and probably represent novel bacterial taxa. Specifically, the tardigrade microbiome appears dominated by Proteobacteria and Bacteroidetes. Some OTUs were shared between different species from geographically distant samples, suggesting the associated bacteria may be widespread. Putative endosymbionts of tardigrades from the order Rickettsiales were identified. Our results indicated that like all other animals, tardigrades have their own microbiota that is different among species, and its assembly is determined by host genotype and environmental influences.

The Aquaporin Channel Repertoire of the Tardigrade Milnesium tardigradum

PubMed Central

Grohme, Markus A.; Mali, Brahim; Wełnicz, Weronika; Michel, Stephanie; Schill, Ralph O.; Frohme, Marcus

2013-01-01

Limno-terrestrial tardigrades are small invertebrates that are subjected to periodic drought of their micro-environment. They have evolved to cope with these unfavorable conditions by anhydrobiosis, an ametabolic state of low cellular water. During drying and rehydration, tardigrades go through drastic changes in cellular water content. By our transcriptome sequencing effort of the limno-terrestrial tardigrade Milnesium tardigradum and by a combination of cloning and targeted sequence assembly, we identified transcripts encoding eleven putative aquaporins. Analysis of these sequences proposed 2 classical aquaporins, 8 aquaglyceroporins and a single potentially intracellular unorthodox aquaporin. Using quantitative real-time PCR we analyzed aquaporin transcript expression in the anhydrobiotic context. We have identified additional unorthodox aquaporins in various insect genomes and have identified a novel common conserved structural feature in these proteins. Analysis of the genomic organization of insect aquaporin genes revealed several conserved gene clusters. PMID:23761966

Looking at tardigrades in a new light: using epifluorescence to interpret structure.

PubMed

Perry, E S; Miller, W R; Lindsay, S

2015-02-01

The use of epifluorescence microscopy coupled with ultraviolet (UV) autofluorescence is suggested as a means to view and interpret tardigrade structures. Endogenous fluorochromes are a known component of tardigrade cuticle, claws and bucco-pharyngeal apparatus. By imaging the autofluorescence from tardigrades, it is possible to document these structures in detail, including the subdivisions and boundaries of echiniscid (heterotardigrade) plates and the nature and spatial relationships of the texture (pores, granules, papillae and tubercles) on the various plates. This allows the determination of taxonomic features not easily seen with other microscopic techniques. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Radiation tolerance in the tardigrade Milnesium tardigradum.

PubMed

Horikawa, Daiki D; Sakashita, Tetsuya; Katagiri, Chihiro; Watanabe, Masahiko; Kikawada, Takahiro; Nakahara, Yuichi; Hamada, Nobuyuki; Wada, Seiichi; Funayama, Tomoo; Higashi, Seigo; Kobayashi, Yasuhiko; Okuda, Takashi; Kuwabara, Mikinori

2006-12-01

Tardigrades are known to survive high doses of ionizing radiation. However, there have been no reports about radiation effects in tardigrades under culture conditions. In this study, we investigated tolerance of the tardigrade, Milnesium tardigradum, against gamma-rays and heavy ions by determining short-term or long-term survival, and reproductive ability after irradiation. Hydrated and anhydrobiotic animals were exposed to gamma-rays (1000 - 7000 Gy) or heavy ions (1000 - 8000 Gy) to evaluate short-term survival at 2, 24 and 48 h post-irradiation. Long-term survival and reproduction were observed up to 31 days after irradiation with gamma-rays (1000 - 4000 Gy). At 48 h after irradiation, median lethal doses were 5000 Gy (gamma-rays) and 6200 Gy (heavy ions) in hydrated animals, and 4400 Gy (gamma-rays) and 5200 Gy (heavy ions) in anhydrobiotic ones. Gamma-irradiation shortened average life span in a dose-dependent manner both in hydrated and anhydrobiotic groups. No irradiated animals laid eggs with one exception in which a hydrated animal irradiated with 2000 Gy of gamma-rays laid 3 eggs, and those eggs failed to hatch, whereas eggs produced by non-irradiated animals hatched successfully. M. tardigradum survives high doses of ionizing radiation in both hydrated and anhydrobiotic states, but irradiation with >1000 Gy makes them sterile.

Two novel heat-soluble protein families abundantly expressed in an anhydrobiotic tardigrade.

PubMed

Yamaguchi, Ayami; Tanaka, Sae; Yamaguchi, Shiho; Kuwahara, Hirokazu; Takamura, Chizuko; Imajoh-Ohmi, Shinobu; Horikawa, Daiki D; Toyoda, Atsushi; Katayama, Toshiaki; Arakawa, Kazuharu; Fujiyama, Asao; Kubo, Takeo; Kunieda, Takekazu

2012-01-01

Tardigrades are able to tolerate almost complete dehydration by reversibly switching to an ametabolic state. This ability is called anhydrobiosis. In the anhydrobiotic state, tardigrades can withstand various extreme environments including space, but their molecular basis remains largely unknown. Late embryogenesis abundant (LEA) proteins are heat-soluble proteins and can prevent protein-aggregation in dehydrated conditions in other anhydrobiotic organisms, but their relevance to tardigrade anhydrobiosis is not clarified. In this study, we focused on the heat-soluble property characteristic of LEA proteins and conducted heat-soluble proteomics using an anhydrobiotic tardigrade. Our heat-soluble proteomics identified five abundant heat-soluble proteins. All of them showed no sequence similarity with LEA proteins and formed two novel protein families with distinct subcellular localizations. We named them Cytoplasmic Abundant Heat Soluble (CAHS) and Secretory Abundant Heat Soluble (SAHS) protein families, according to their localization. Both protein families were conserved among tardigrades, but not found in other phyla. Although CAHS protein was intrinsically unstructured and SAHS protein was rich in β-structure in the hydrated condition, proteins in both families changed their conformation to an α-helical structure in water-deficient conditions as LEA proteins do. Two conserved repeats of 19-mer motifs in CAHS proteins were capable to form amphiphilic stripes in α-helices, suggesting their roles as molecular shield in water-deficient condition, though charge distribution pattern in α-helices were different between CAHS and LEA proteins. Tardigrades might have evolved novel protein families with a heat-soluble property and this study revealed a novel repertoire of major heat-soluble proteins in these anhydrobiotic animals.

A Hypothesis for the Composition of the Tardigrade Brain and its Implications for Panarthropod Brain Evolution.

PubMed

Smith, Frank W; Bartels, Paul J; Goldstein, Bob

2017-09-01

Incredibly disparate brain types are found in Metazoa, which raises the question of how this disparity evolved. Ecdysozoa includes representatives that exhibit ring-like brains-the Cycloneuralia-and representatives that exhibit ganglionic brains-the Panarthropoda (Euarthropoda, Onychophora, and Tardigrada). The evolutionary steps leading to these distinct brain types are unclear. Phylogenomic analyses suggest that the enigmatic Tardigrada is a closely related outgroup of a Euarthropoda + Onychophora clade; as such, the brains of tardigrades may provide insight into the evolution of ecdysozoan brains. Recently, evolutionarily salient questions have arisen regarding the composition of the tardigrade brain. To address these questions, we investigated brain anatomy in four tardigrade species-Hypsibius dujardini, Milnesium n. sp., Echiniscus n. sp., and Batillipes n. sp.-that together span Tardigrada. Our results suggest that general brain morphology is conserved across Tardigrada. Based on our results we present a hypothesis that proposes direct parallels between the tardigrade brain and the segmental trunk ganglia of the tardigrade ventral nervous system. In this hypothesis, brain neuropil nearly circumscribes the tardigrade foregut. We suggest that the tardigrade brain retains aspects of an ancestral cycloneuralian brain, while exhibiting ganglionic structure characteristic of euarthropods and onychophorans. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.All rights reserved. For permissions please email: journals.permissions@oup.com.

Transcriptome survey of the anhydrobiotic tardigrade Milnesium tardigradum in comparison with Hypsibius dujardini and Richtersius coronifer

PubMed Central

2010-01-01

Background The phenomenon of desiccation tolerance, also called anhydrobiosis, involves the ability of an organism to survive the loss of almost all cellular water without sustaining irreversible damage. Although there are several physiological, morphological and ecological studies on tardigrades, only limited DNA sequence information is available. Therefore, we explored the transcriptome in the active and anhydrobiotic state of the tardigrade Milnesium tardigradum which has extraordinary tolerance to desiccation and freezing. In this study, we present the first overview of the transcriptome of M. tardigradum and its response to desiccation and discuss potential parallels to stress responses in other organisms. Results We sequenced a total of 9984 expressed sequence tags (ESTs) from two cDNA libraries from the eutardigrade M. tardigradum in its active and inactive, anhydrobiotic (tun) stage. Assembly of these ESTs resulted in 3283 putative unique transcripts, whereof ~50% showed significant sequence similarity to known genes. The resulting unigenes were functionally annotated using the Gene Ontology (GO) vocabulary. A GO term enrichment analysis revealed several GOs that were significantly underrepresented in the inactive stage. Furthermore we compared the putative unigenes of M. tardigradum with ESTs from two other eutardigrade species that are available from public sequence databases, namely Richtersius coronifer and Hypsibius dujardini. The processed sequences of the three tardigrade species revealed similar functional content and the M. tardigradum dataset contained additional sequences from tardigrades not present in the other two. Conclusions This study describes novel sequence data from the tardigrade M. tardigradum, which significantly contributes to the available tardigrade sequence data and will help to establish this extraordinary tardigrade as a model for studying anhydrobiosis. Functional comparison of active and anhydrobiotic tardigrades revealed a

Transcriptome survey of the anhydrobiotic tardigrade Milnesium tardigradum in comparison with Hypsibius dujardini and Richtersius coronifer.

PubMed

Mali, Brahim; Grohme, Markus A; Förster, Frank; Dandekar, Thomas; Schnölzer, Martina; Reuter, Dirk; Wełnicz, Weronika; Schill, Ralph O; Frohme, Marcus

2010-03-12

The phenomenon of desiccation tolerance, also called anhydrobiosis, involves the ability of an organism to survive the loss of almost all cellular water without sustaining irreversible damage. Although there are several physiological, morphological and ecological studies on tardigrades, only limited DNA sequence information is available. Therefore, we explored the transcriptome in the active and anhydrobiotic state of the tardigrade Milnesium tardigradum which has extraordinary tolerance to desiccation and freezing. In this study, we present the first overview of the transcriptome of M. tardigradum and its response to desiccation and discuss potential parallels to stress responses in other organisms. We sequenced a total of 9984 expressed sequence tags (ESTs) from two cDNA libraries from the eutardigrade M. tardigradum in its active and inactive, anhydrobiotic (tun) stage. Assembly of these ESTs resulted in 3283 putative unique transcripts, whereof approximately 50% showed significant sequence similarity to known genes. The resulting unigenes were functionally annotated using the Gene Ontology (GO) vocabulary. A GO term enrichment analysis revealed several GOs that were significantly underrepresented in the inactive stage. Furthermore we compared the putative unigenes of M. tardigradum with ESTs from two other eutardigrade species that are available from public sequence databases, namely Richtersius coronifer and Hypsibius dujardini. The processed sequences of the three tardigrade species revealed similar functional content and the M. tardigradum dataset contained additional sequences from tardigrades not present in the other two. This study describes novel sequence data from the tardigrade M. tardigradum, which significantly contributes to the available tardigrade sequence data and will help to establish this extraordinary tardigrade as a model for studying anhydrobiosis. Functional comparison of active and anhydrobiotic tardigrades revealed a differential

Transcriptome Analysis in Tardigrade Species Reveals Specific Molecular Pathways for Stress Adaptations

PubMed Central

Förster, Frank; Beisser, Daniela; Grohme, Markus A.; Liang, Chunguang; Mali, Brahim; Siegl, Alexander Matthias; Engelmann, Julia C.; Shkumatov, Alexander V.; Schokraie, Elham; Müller, Tobias; Schnölzer, Martina; Schill, Ralph O.; Frohme, Marcus; Dandekar, Thomas

2012-01-01

Tardigrades have unique stress-adaptations that allow them to survive extremes of cold, heat, radiation and vacuum. To study this, encoded protein clusters and pathways from an ongoing transcriptome study on the tardigrade Milnesium tardigradum were analyzed using bioinformatics tools and compared to expressed sequence tags (ESTs) from Hypsibius dujardini, revealing major pathways involved in resistance against extreme environmental conditions. ESTs are available on the Tardigrade Workbench along with software and databank updates. Our analysis reveals that RNA stability motifs for M. tardigradum are different from typical motifs known from higher animals. M. tardigradum and H. dujardini protein clusters and conserved domains imply metabolic storage pathways for glycogen, glycolipids and specific secondary metabolism as well as stress response pathways (including heat shock proteins, bmh2, and specific repair pathways). Redox-, DNA-, stress- and protein protection pathways complement specific repair capabilities to achieve the strong robustness of M. tardigradum. These pathways are partly conserved in other animals and their manipulation could boost stress adaptation even in human cells. However, the unique combination of resistance and repair pathways make tardigrades and M. tardigradum in particular so highly stress resistant. PMID:22563243

Transcriptome analysis in tardigrade species reveals specific molecular pathways for stress adaptations.

PubMed

Förster, Frank; Beisser, Daniela; Grohme, Markus A; Liang, Chunguang; Mali, Brahim; Siegl, Alexander Matthias; Engelmann, Julia C; Shkumatov, Alexander V; Schokraie, Elham; Müller, Tobias; Schnölzer, Martina; Schill, Ralph O; Frohme, Marcus; Dandekar, Thomas

2012-01-01

Tardigrades have unique stress-adaptations that allow them to survive extremes of cold, heat, radiation and vacuum. To study this, encoded protein clusters and pathways from an ongoing transcriptome study on the tardigrade Milnesium tardigradum were analyzed using bioinformatics tools and compared to expressed sequence tags (ESTs) from Hypsibius dujardini, revealing major pathways involved in resistance against extreme environmental conditions. ESTs are available on the Tardigrade Workbench along with software and databank updates. Our analysis reveals that RNA stability motifs for M. tardigradum are different from typical motifs known from higher animals. M. tardigradum and H. dujardini protein clusters and conserved domains imply metabolic storage pathways for glycogen, glycolipids and specific secondary metabolism as well as stress response pathways (including heat shock proteins, bmh2, and specific repair pathways). Redox-, DNA-, stress- and protein protection pathways complement specific repair capabilities to achieve the strong robustness of M. tardigradum. These pathways are partly conserved in other animals and their manipulation could boost stress adaptation even in human cells. However, the unique combination of resistance and repair pathways make tardigrades and M. tardigradum in particular so highly stress resistant.

Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade

PubMed Central

Boothby, Thomas C.; Tenlen, Jennifer R.; Smith, Frank W.; Wang, Jeremy R.; Patanella, Kiera A.; Osborne Nishimura, Erin; Tintori, Sophia C.; Li, Qing; Jones, Corbin D.; Yandell, Mark; Glasscock, Jarret; Goldstein, Bob

2015-01-01

Horizontal gene transfer (HGT), or the transfer of genes between species, has been recognized recently as more pervasive than previously suspected. Here, we report evidence for an unprecedented degree of HGT into an animal genome, based on a draft genome of a tardigrade, Hypsibius dujardini. Tardigrades are microscopic eight-legged animals that are famous for their ability to survive extreme conditions. Genome sequencing, direct confirmation of physical linkage, and phylogenetic analysis revealed that a large fraction of the H. dujardini genome is derived from diverse bacteria as well as plants, fungi, and Archaea. We estimate that approximately one-sixth of tardigrade genes entered by HGT, nearly double the fraction found in the most extreme cases of HGT into animals known to date. Foreign genes have supplemented, expanded, and even replaced some metazoan gene families within the tardigrade genome. Our results demonstrate that an unexpectedly large fraction of an animal genome can be derived from foreign sources. We speculate that animals that can survive extremes may be particularly prone to acquiring foreign genes. PMID:26598659

Evidence for extensive horizontal gene transfer from the draft genome of a tardigrade.

PubMed

Boothby, Thomas C; Tenlen, Jennifer R; Smith, Frank W; Wang, Jeremy R; Patanella, Kiera A; Nishimura, Erin Osborne; Tintori, Sophia C; Li, Qing; Jones, Corbin D; Yandell, Mark; Messina, David N; Glasscock, Jarret; Goldstein, Bob

2015-12-29

Horizontal gene transfer (HGT), or the transfer of genes between species, has been recognized recently as more pervasive than previously suspected. Here, we report evidence for an unprecedented degree of HGT into an animal genome, based on a draft genome of a tardigrade, Hypsibius dujardini. Tardigrades are microscopic eight-legged animals that are famous for their ability to survive extreme conditions. Genome sequencing, direct confirmation of physical linkage, and phylogenetic analysis revealed that a large fraction of the H. dujardini genome is derived from diverse bacteria as well as plants, fungi, and Archaea. We estimate that approximately one-sixth of tardigrade genes entered by HGT, nearly double the fraction found in the most extreme cases of HGT into animals known to date. Foreign genes have supplemented, expanded, and even replaced some metazoan gene families within the tardigrade genome. Our results demonstrate that an unexpectedly large fraction of an animal genome can be derived from foreign sources. We speculate that animals that can survive extremes may be particularly prone to acquiring foreign genes.

Tolerance to Gamma Radiation in the Tardigrade Hypsibius dujardini from Embryo to Adult Correlate Inversely with Cellular Proliferation.

PubMed

Beltrán-Pardo, Eliana; Jönsson, K Ingemar; Harms-Ringdahl, Mats; Haghdoost, Siamak; Wojcik, Andrzej

2015-01-01

Tardigrades are highly tolerant to desiccation and ionizing radiation but the mechanisms of this tolerance are not well understood. In this paper, we report studies on dose responses of adults and eggs of the tardigrade Hypsibius dujardini exposed to gamma radiation. In adults the LD50/48h for survival was estimated at ~ 4200 Gy, and doses higher than 100 Gy reduced both fertility and hatchability of laid eggs drastically. We also evaluated the effect of radiation (doses 50 Gy, 200 Gy, 500 Gy) on eggs in the early and late embryonic stage of development, and observed a reduced hatchability in the early stage, while no effect was found in the late stage of development. Survival of juveniles from irradiated eggs was highly affected by a 500 Gy dose, both in the early and the late stage. Juveniles hatched from eggs irradiated at 50 Gy and 200 Gy developed into adults and produced offspring, but their fertility was reduced compared to the controls. Finally we measured the effect of low temperature during irradiation at 4000 Gy and 4500 Gy on survival in adult tardigrades, and observed a slight delay in the expressed mortality when tardigrades were irradiated on ice. Since H. dujardini is a freshwater tardigrade with lower tolerance to desiccation compared to limno-terrestrial tardigrades, the high radiation tolerance in adults, similar to limno-terrestrial tardigrades, is unexpected and seems to challenge the idea that desiccation and radiation tolerance rely on the same molecular mechanisms. We suggest that the higher radiation tolerance in adults and late stage embryos of H. dujardini (and in other studied tardigrades) compared to early stage embryos may partly be due to limited mitotic activity, since tardigrades have a low degree of somatic cell division (eutely), and dividing cells are known to be more sensitive to radiation.

Tolerance to Gamma Radiation in the Tardigrade Hypsibius dujardini from Embryo to Adult Correlate Inversely with Cellular Proliferation

PubMed Central

Beltrán-Pardo, Eliana; Jönsson, K. Ingemar; Harms-Ringdahl, Mats; Haghdoost, Siamak; Wojcik, Andrzej

2015-01-01

Tardigrades are highly tolerant to desiccation and ionizing radiation but the mechanisms of this tolerance are not well understood. In this paper, we report studies on dose responses of adults and eggs of the tardigrade Hypsibius dujardini exposed to gamma radiation. In adults the LD50/48h for survival was estimated at ~ 4200 Gy, and doses higher than 100 Gy reduced both fertility and hatchability of laid eggs drastically. We also evaluated the effect of radiation (doses 50 Gy, 200 Gy, 500 Gy) on eggs in the early and late embryonic stage of development, and observed a reduced hatchability in the early stage, while no effect was found in the late stage of development. Survival of juveniles from irradiated eggs was highly affected by a 500 Gy dose, both in the early and the late stage. Juveniles hatched from eggs irradiated at 50 Gy and 200 Gy developed into adults and produced offspring, but their fertility was reduced compared to the controls. Finally we measured the effect of low temperature during irradiation at 4000 Gy and 4500 Gy on survival in adult tardigrades, and observed a slight delay in the expressed mortality when tardigrades were irradiated on ice. Since H. dujardini is a freshwater tardigrade with lower tolerance to desiccation compared to limno-terrestrial tardigrades, the high radiation tolerance in adults, similar to limno-terrestrial tardigrades, is unexpected and seems to challenge the idea that desiccation and radiation tolerance rely on the same molecular mechanisms. We suggest that the higher radiation tolerance in adults and late stage embryos of H. dujardini (and in other studied tardigrades) compared to early stage embryos may partly be due to limited mitotic activity, since tardigrades have a low degree of somatic cell division (eutely), and dividing cells are known to be more sensitive to radiation. PMID:26208275

RNA interference can be used to disrupt gene function in tardigrades.

PubMed

Tenlen, Jennifer R; McCaskill, Shaina; Goldstein, Bob

2013-05-01

How morphological diversity arises is a key question in evolutionary developmental biology. As a long-term approach to address this question, we are developing the water bear Hypsibius dujardini (Phylum Tardigrada) as a model system. We expect that using a close relative of two well-studied models, Drosophila (Phylum Arthropoda) and Caenorhabditis elegans (Phylum Nematoda), will facilitate identifying genetic pathways relevant to understanding the evolution of development. Tardigrades are also valuable research subjects for investigating how organisms and biological materials can survive extreme conditions. Methods to disrupt gene activity are essential to each of these efforts, but no such method yet exists for the Phylum Tardigrada. We developed a protocol to disrupt tardigrade gene functions by double-stranded RNA-mediated RNA interference (RNAi). We showed that targeting tardigrade homologs of essential developmental genes by RNAi produced embryonic lethality, whereas targeting green fluorescent protein did not. Disruption of gene functions appears to be relatively specific by two criteria: targeting distinct genes resulted in distinct phenotypes that were consistent with predicted gene functions and by RT-PCR, RNAi reduced the level of a target mRNA and not a control mRNA. These studies represent the first evidence that gene functions can be disrupted by RNAi in the phylum Tardigrada. Our results form a platform for dissecting tardigrade gene functions for understanding the evolution of developmental mechanisms and survival in extreme environments.

Novel Mitochondria-Targeted Heat-Soluble Proteins Identified in the Anhydrobiotic Tardigrade Improve Osmotic Tolerance of Human Cells

PubMed Central

Tanaka, Sae; Tanaka, Junko; Miwa, Yoshihiro; Horikawa, Daiki D.; Katayama, Toshiaki; Arakawa, Kazuharu; Toyoda, Atsushi; Kubo, Takeo; Kunieda, Takekazu

2015-01-01

Tardigrades are able to tolerate almost complete dehydration through transition to a metabolically inactive state, called “anhydrobiosis”. Late Embryogenesis Abundant (LEA) proteins are heat-soluble proteins involved in the desiccation tolerance of many anhydrobiotic organisms. Tardigrades, Ramazzottius varieornatus, however, express predominantly tardigrade-unique heat-soluble proteins: CAHS (Cytoplasmic Abundant Heat Soluble) and SAHS (Secretory Abundant Heat Soluble) proteins, which are secreted or localized in most intracellular compartments, except the mitochondria. Although mitochondrial integrity is crucial to ensure cellular survival, protective molecules for mitochondria have remained elusive. Here, we identified two novel mitochondrial heat-soluble proteins, RvLEAM and MAHS (Mitochondrial Abundant Heat Soluble), as potent mitochondrial protectants from Ramazzottius varieornatus. RvLEAM is a group3 LEA protein and immunohistochemistry confirmed its mitochondrial localization in tardigrade cells. MAHS-green fluorescent protein fusion protein localized in human mitochondria and was heat-soluble in vitro, though no sequence similarity with other known proteins was found, and one region was conserved among tardigrades. Furthermore, we demonstrated that RvLEAM protein as well as MAHS protein improved the hyperosmotic tolerance of human cells. The findings of the present study revealed that tardigrade mitochondria contain at least two types of heat-soluble proteins that might have protective roles in water-deficient environments. PMID:25675104

Novel mitochondria-targeted heat-soluble proteins identified in the anhydrobiotic Tardigrade improve osmotic tolerance of human cells.

PubMed

Tanaka, Sae; Tanaka, Junko; Miwa, Yoshihiro; Horikawa, Daiki D; Katayama, Toshiaki; Arakawa, Kazuharu; Toyoda, Atsushi; Kubo, Takeo; Kunieda, Takekazu

2015-01-01

Tardigrades are able to tolerate almost complete dehydration through transition to a metabolically inactive state, called "anhydrobiosis". Late Embryogenesis Abundant (LEA) proteins are heat-soluble proteins involved in the desiccation tolerance of many anhydrobiotic organisms. Tardigrades, Ramazzottius varieornatus, however, express predominantly tardigrade-unique heat-soluble proteins: CAHS (Cytoplasmic Abundant Heat Soluble) and SAHS (Secretory Abundant Heat Soluble) proteins, which are secreted or localized in most intracellular compartments, except the mitochondria. Although mitochondrial integrity is crucial to ensure cellular survival, protective molecules for mitochondria have remained elusive. Here, we identified two novel mitochondrial heat-soluble proteins, RvLEAM and MAHS (Mitochondrial Abundant Heat Soluble), as potent mitochondrial protectants from Ramazzottius varieornatus. RvLEAM is a group3 LEA protein and immunohistochemistry confirmed its mitochondrial localization in tardigrade cells. MAHS-green fluorescent protein fusion protein localized in human mitochondria and was heat-soluble in vitro, though no sequence similarity with other known proteins was found, and one region was conserved among tardigrades. Furthermore, we demonstrated that RvLEAM protein as well as MAHS protein improved the hyperosmotic tolerance of human cells. The findings of the present study revealed that tardigrade mitochondria contain at least two types of heat-soluble proteins that might have protective roles in water-deficient environments.

The tardigrade Hypsibius dujardini, a new model for studying the evolution of development.

PubMed

Gabriel, Willow N; McNuff, Robert; Patel, Sapna K; Gregory, T Ryan; Jeck, William R; Jones, Corbin D; Goldstein, Bob

2007-12-15

Studying development in diverse taxa can address a central issue in evolutionary biology: how morphological diversity arises through the evolution of developmental mechanisms. Two of the best-studied developmental model organisms, the arthropod Drosophila and the nematode Caenorhabditis elegans, have been found to belong to a single protostome superclade, the Ecdysozoa. This finding suggests that a closely related ecdysozoan phylum could serve as a valuable model for studying how developmental mechanisms evolve in ways that can produce diverse body plans. Tardigrades, also called water bears, make up a phylum of microscopic ecdysozoan animals. Tardigrades share many characteristics with C. elegans and Drosophila that could make them useful laboratory models, but long-term culturing of tardigrades historically has been a challenge, and there have been few studies of tardigrade development. Here, we show that the tardigrade Hypsibius dujardini can be cultured continuously for decades and can be cryopreserved. We report that H. dujardini has a compact genome, a little smaller than that of C. elegans or Drosophila, and that sequence evolution has occurred at a typical rate. H. dujardini has a short generation time, 13-14 days at room temperature. We have found that the embryos of H. dujardini have a stereotyped cleavage pattern with asymmetric cell divisions, nuclear migrations, and cell migrations occurring in reproducible patterns. We present a cell lineage of the early embryo and an embryonic staging series. We expect that these data can serve as a platform for using H. dujardini as a model for studying the evolution of developmental mechanisms.

RNA interference can be used to disrupt gene function in tardigrades

PubMed Central

Tenlen, Jennifer R.; McCaskill, Shaina; Goldstein, Bob

2012-01-01

How morphological diversity arises is a key question in evolutionary developmental biology. As a long-term approach to address this question, we are developing the water bear Hypsibius dujardini (Phylum Tardigrada) as a model system. We expect that using a close relative of two well-studied models, Drosophila (Phylum Arthropoda) and Caenorhabditis elegans (Phylum Nematoda), will facilitate identifying genetic pathways relevant to understanding the evolution of development. Tardigrades are also valuable research subjects for investigating how organisms and biological materials can survive extreme conditions. Methods to disrupt gene activity are essential to each of these efforts, but no such method yet exists for the Phylum Tardigrada. We developed a protocol to disrupt tardigrade gene functions by double-stranded RNA-mediated RNA interference (RNAi). We show that targeting tardigrade homologs of essential developmental genes by RNAi produced embryonic lethality, whereas targeting green fluorescent protein did not. Disruption of gene functions appears to be relatively specific by two criteria: targeting distinct genes resulted in distinct phenotypes that were consistent with predicted gene functions, and by RT-PCR, RNAi reduced the level of a target mRNA and not a control mRNA. These studies represent the first evidence that gene functions can be disrupted by RNAi in the phylum Tardigrada. Our results form a platform for dissecting tardigrade gene functions for understanding the evolution of developmental mechanisms and survival in extreme environments. PMID:23187800

Comparative Investigation of Copper Tolerance and Identification of Putative Tolerance Related Genes in Tardigrades.

PubMed

Hygum, Thomas L; Fobian, Dannie; Kamilari, Maria; Jørgensen, Aslak; Schiøtt, Morten; Grosell, Martin; Møbjerg, Nadja

2017-01-01

Tardigrades are microscopic aquatic animals renowned for their tolerance toward extreme environmental conditions. The current study is the first to investigate their tolerance toward heavy metals and we present a novel tardigrade toxicant tolerance assay based on activity assessments as a measure of survival. Specifically, we compare tolerance toward copper in four species representing different evolutionary lineages, habitats and adaptation strategies, i.e., a marine heterotardigrade, Echiniscoides sigismundi , a limno-terrestrial heterotardigrade, Echiniscus testudo , a limno-terrestrial eutardigrade, Ramazzottius oberhaeuseri , and a marine eutardigrade, Halobiotus crispae . The latter was sampled at a time of year, when the population is predominantly represented by aberrant P1 cysts, while the other species were in normal active states prior to exposure. Based on volume measurements and a general relation between body mass and copper tolerance, expected tardigrade EC50 values were estimated at 0.5-2 μg l -1 . Following 24 h of exposure, tolerance was high with no apparent link to lineage or habitat. EC50s (95% CI), 24 h after exposure, were estimated at 178 (168-186) and 310 (295-328) μg l -1 , respectively, for E. sigismundi and R. oberhaeuseri , whereas E. testudo and H. crispae were less affected. Highest tolerance was observed in H. crispae with a mean ± s.e.m . activity of 77 ± 2% ( n = 3) 24 h after removal from ~3 mg l -1 copper, suggesting that tardigrade cysts have increased tolerance toward toxicants. In order to identify putative tolerance related genes, an E. sigismundi transcriptome was searched for key enzymes involved in osmoregulation, antioxidant defense and copper metabolism. We found high expression of Na/K ATPase and carbonic anhydrase, known targets for copper. Our transcriptome, furthermore, revealed high expression of antioxidant enzymes, copper transporters, ATOX1, and a Cu-ATPase. In summary, our results indicate that tardigrades

Recovery and reproduction of an Antarctic tardigrade retrieved from a moss sample frozen for over 30 years.

PubMed

Tsujimoto, Megumu; Imura, Satoshi; Kanda, Hiroshi

2016-02-01

Long-term survival has been one of the most studied of the extraordinary physiological characteristics of cryptobiosis in micrometazoans such as nematodes, tardigrades and rotifers. In the available studies of long-term survival of micrometazoans, instances of survival have been the primary observation, and recovery conditions of animals or subsequent reproduction are generally not reported. We therefore documented recovery conditions and reproduction immediately following revival of tardigrades retrieved from a frozen moss sample collected in Antarctica in 1983 and stored at -20 °C for 30.5 years. We recorded recovery of two individuals and development of a separate egg of the Antarctic tardigrade, Acutuncus antarcticus, providing the longest records of survival for tardigrades as animals or eggs. One of the two resuscitated individuals and the hatchling successfully reproduced repeatedly after their recovery from long-term cryptobiosis. This considerable extension of the known length of long-term survival of tardigrades recorded in our study is interpreted as being associated with the minimum oxidative damage likely to have resulted from storage under stable frozen conditions. The long recovery times of the revived tardigrades observed is suggestive of the requirement for repair of damage accrued over 30 years of cryptobiosis. Further more detailed studies will improve understanding of mechanisms and conditions underlying the long-term survival of cryptobiotic organisms. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

DNA Protection Protein, a Novel Mechanism of Radiation Tolerance: Lessons from Tardigrades

PubMed Central

Hashimoto, Takuma; Kunieda, Takekazu

2017-01-01

Genomic DNA stores all genetic information and is indispensable for maintenance of normal cellular activity and propagation. Radiation causes severe DNA lesions, including double-strand breaks, and leads to genome instability and even lethality. Regardless of the toxicity of radiation, some organisms exhibit extraordinary tolerance against radiation. These organisms are supposed to possess special mechanisms to mitigate radiation-induced DNA damages. Extensive study using radiotolerant bacteria suggested that effective protection of proteins and enhanced DNA repair system play important roles in tolerability against high-dose radiation. Recent studies using an extremotolerant animal, the tardigrade, provides new evidence that a tardigrade-unique DNA-associating protein, termed Dsup, suppresses the occurrence of DNA breaks by radiation in human-cultured cells. In this review, we provide a brief summary of the current knowledge on extremely radiotolerant animals, and present novel insights from the tardigrade research, which expand our understanding on molecular mechanism of exceptional radio-tolerability. PMID:28617314

Survival of freezing by hydrated tardigrades inhabiting terrestrial and freshwater habitats.

PubMed

Guidetti, Roberto; Altiero, Tiziana; Bertolani, Roberto; Grazioso, Pasqualina; Rebecchi, Lorena

2011-04-01

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 death or development of specific adaptations. Ice formation is a major variable affecting the 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 the active hydrated state using seven tardigrade species differing in phylogenetic position and collected at various altitudes and from different habitats in a temperate area. Specimens 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 to active life were both inversely related to the cooling rate, highly significant interspecific differences were found. Species survival ability ranged from excellent to none. Species living in xeric habitats withstood freezing better than those living in hygrophilous habitats, while true limnic species did not exhibit any cryobiotic ability. The ability to withstand freezing seems linked to the anhydrobiotic ability. The differences in cryptobiotic performance among tardigrade species seem more influenced by selective pressures linked to local adaptation to habitat characteristics than by phylogenetic relationships. Copyright © 2011 Elsevier GmbH. All rights reserved.

Tardigrades: In the Classroom, Laboratory, and on the Internet.

ERIC Educational Resources Information Center

Miller, William R.; Case, Steve B.

1998-01-01

Details the development of the Tardigrade Survey, focusing on the questions related to how to present projects. Recommends challenging high school students in ways that stimulate their interest in the investigatory approach. (DDR)

Proteomic analysis of tardigrades: towards a better understanding of molecular mechanisms by anhydrobiotic organisms.

PubMed

Schokraie, Elham; Hotz-Wagenblatt, Agnes; Warnken, Uwe; Mali, Brahim; Frohme, Marcus; Förster, Frank; Dandekar, Thomas; Hengherr, Steffen; Schill, Ralph O; Schnölzer, Martina

2010-03-03

Tardigrades are small, multicellular invertebrates which are able to survive times of unfavourable environmental conditions using their well-known capability to undergo cryptobiosis at any stage of their life cycle. Milnesium tardigradum has become a powerful model system for the analysis of cryptobiosis. While some genetic information is already available for Milnesium tardigradum the proteome is still to be discovered. Here we present to the best of our knowledge the first comprehensive study of Milnesium tardigradum on the protein level. To establish a proteome reference map we developed optimized protocols for protein extraction from tardigrades in the active state and for separation of proteins by high resolution two-dimensional gel electrophoresis. Since only limited sequence information of M. tardigradum on the genome and gene expression level is available to date in public databases we initiated in parallel a tardigrade EST sequencing project to allow for protein identification by electrospray ionization tandem mass spectrometry. 271 out of 606 analyzed protein spots could be identified by searching against the publicly available NCBInr database as well as our newly established tardigrade protein database corresponding to 144 unique proteins. Another 150 spots could be identified in the tardigrade clustered EST database corresponding to 36 unique contigs and ESTs. Proteins with annotated function were further categorized in more detail by their molecular function, biological process and cellular component. For the proteins of unknown function more information could be obtained by performing a protein domain annotation analysis. Our results include proteins like protein member of different heat shock protein families and LEA group 3, which might play important roles in surviving extreme conditions. The proteome reference map of Milnesium tardigradum provides the basis for further studies in order to identify and characterize the biochemical mechanisms of

Proteomic Analysis of Tardigrades: Towards a Better Understanding of Molecular Mechanisms by Anhydrobiotic Organisms

PubMed Central

Schokraie, Elham; Hotz-Wagenblatt, Agnes; Warnken, Uwe; Mali, Brahim; Frohme, Marcus; Förster, Frank; Dandekar, Thomas; Hengherr, Steffen; Schill, Ralph O.; Schnölzer, Martina

2010-01-01

Background Tardigrades are small, multicellular invertebrates which are able to survive times of unfavourable environmental conditions using their well-known capability to undergo cryptobiosis at any stage of their life cycle. Milnesium tardigradum has become a powerful model system for the analysis of cryptobiosis. While some genetic information is already available for Milnesium tardigradum the proteome is still to be discovered. Principal Findings Here we present to the best of our knowledge the first comprehensive study of Milnesium tardigradum on the protein level. To establish a proteome reference map we developed optimized protocols for protein extraction from tardigrades in the active state and for separation of proteins by high resolution two-dimensional gel electrophoresis. Since only limited sequence information of M. tardigradum on the genome and gene expression level is available to date in public databases we initiated in parallel a tardigrade EST sequencing project to allow for protein identification by electrospray ionization tandem mass spectrometry. 271 out of 606 analyzed protein spots could be identified by searching against the publicly available NCBInr database as well as our newly established tardigrade protein database corresponding to 144 unique proteins. Another 150 spots could be identified in the tardigrade clustered EST database corresponding to 36 unique contigs and ESTs. Proteins with annotated function were further categorized in more detail by their molecular function, biological process and cellular component. For the proteins of unknown function more information could be obtained by performing a protein domain annotation analysis. Our results include proteins like protein member of different heat shock protein families and LEA group 3, which might play important roles in surviving extreme conditions. Conclusions The proteome reference map of Milnesium tardigradum provides the basis for further studies in order to identify and

Comparative Investigation of Copper Tolerance and Identification of Putative Tolerance Related Genes in Tardigrades

PubMed Central

Hygum, Thomas L.; Fobian, Dannie; Kamilari, Maria; Jørgensen, Aslak; Schiøtt, Morten; Grosell, Martin; Møbjerg, Nadja

2017-01-01

Tardigrades are microscopic aquatic animals renowned for their tolerance toward extreme environmental conditions. The current study is the first to investigate their tolerance toward heavy metals and we present a novel tardigrade toxicant tolerance assay based on activity assessments as a measure of survival. Specifically, we compare tolerance toward copper in four species representing different evolutionary lineages, habitats and adaptation strategies, i.e., a marine heterotardigrade, Echiniscoides sigismundi, a limno-terrestrial heterotardigrade, Echiniscus testudo, a limno-terrestrial eutardigrade, Ramazzottius oberhaeuseri, and a marine eutardigrade, Halobiotus crispae. The latter was sampled at a time of year, when the population is predominantly represented by aberrant P1 cysts, while the other species were in normal active states prior to exposure. Based on volume measurements and a general relation between body mass and copper tolerance, expected tardigrade EC50 values were estimated at 0.5–2 μg l−1. Following 24 h of exposure, tolerance was high with no apparent link to lineage or habitat. EC50s (95% CI), 24 h after exposure, were estimated at 178 (168–186) and 310 (295–328) μg l−1, respectively, for E. sigismundi and R. oberhaeuseri, whereas E. testudo and H. crispae were less affected. Highest tolerance was observed in H. crispae with a mean ± s.e.m. activity of 77 ± 2% (n = 3) 24 h after removal from ~3 mg l−1 copper, suggesting that tardigrade cysts have increased tolerance toward toxicants. In order to identify putative tolerance related genes, an E. sigismundi transcriptome was searched for key enzymes involved in osmoregulation, antioxidant defense and copper metabolism. We found high expression of Na/K ATPase and carbonic anhydrase, known targets for copper. Our transcriptome, furthermore, revealed high expression of antioxidant enzymes, copper transporters, ATOX1, and a Cu-ATPase. In summary, our results indicate that tardigrades

The Compact Body Plan of Tardigrades Evolved by the Loss of a Large Body Region.

PubMed

Smith, Frank W; Boothby, Thomas C; Giovannini, Ilaria; Rebecchi, Lorena; Jockusch, Elizabeth L; Goldstein, Bob

2016-01-25

The superphylum Panarthropoda (Arthropoda, Onychophora, and Tardigrada) exhibits a remarkable diversity of segment morphologies, enabling these animals to occupy diverse ecological niches. The molecular identities of these segments are specified by Hox genes and other axis patterning genes during development [1, 2]. Comparisons of molecular segment identities between arthropod and onychophoran species have yielded important insights into the origins and diversification of their body plans [3-9]. However, the relationship of the segments of tardigrades to those of arthropods and onychophorans has remained enigmatic [10, 11], limiting our understanding of early panarthropod body plan diversification. Here, we reveal molecular identities for all of the segments of a tardigrade. Based on our analysis, we conclude that tardigrades have lost a large intermediate region of the body axis-a region corresponding to the entire thorax and most of the abdomen of insects-and that they have lost the Hox genes that originally specified this region. Our data suggest that nearly the entire tardigrade body axis is homologous to just the head region of arthropods. Based on our results, we reconstruct a last common ancestor of Panarthropoda that had a relatively elongate body plan like most arthropods and onychophorans, rather than a compact, tardigrade-like body plan. These results demonstrate that the body plan of an animal phylum can originate by the loss of a large part of the body. Copyright © 2016 Elsevier Ltd. All rights reserved.

Nature, Source and Function of Pigments in Tardigrades: In Vivo Raman Imaging of Carotenoids in Echiniscus blumi

PubMed Central

Bonifacio, Alois; Guidetti, Roberto; Altiero, Tiziana; Sergo, Valter; Rebecchi, Lorena

2012-01-01

Tardigrades are microscopic aquatic animals with remarkable abilities to withstand harsh physical conditions such as dehydration or exposure to harmful highly energetic radiation. The mechanisms responsible for such robustness are presently little known, but protection against oxidative stresses is thought to play a role. Despite the fact that many tardigrade species are variously pigmented, scarce information is available about this characteristic. By applying Raman micro-spectroscopy on living specimens, pigments in the tardigrade Echiniscus blumi are identified as carotenoids, and their distribution within the animal body is visualized. The dietary origin of these pigments is demonstrated, as well as their presence in the eggs and in eye-spots of these animals, together with their absence in the outer layer of the animal (i.e., cuticle and epidermis). Using in-vivo semi-quantitative Raman micro-spectroscopy, a decrease in carotenoid content is detected after inducing oxidative stress, demonstrating that this approach can be used for studying the role of carotenoids in oxidative stress-related processes in tardigrades. This approach could be thus used in further investigations to test several hypotheses concerning the function of these carotenoids in tardigrades as photo-protective pigments against ionizing radiations or as antioxidants defending these organisms against the oxidative stress occurring during desiccation processes. PMID:23185564

The nervous and visual systems of onychophorans and tardigrades: learning about arthropod evolution from their closest relatives.

PubMed

Martin, Christine; Gross, Vladimir; Hering, Lars; Tepper, Benjamin; Jahn, Henry; de Sena Oliveira, Ivo; Stevenson, Paul Anthony; Mayer, Georg

2017-08-01

Understanding the origin and evolution of arthropods requires examining their closest outgroups, the tardigrades (water bears) and onychophorans (velvet worms). Despite the rise of molecular techniques, the phylogenetic positions of tardigrades and onychophorans in the panarthropod tree (onychophorans + tardigrades + arthropods) remain unresolved. Hence, these methods alone are currently insufficient for clarifying the panarthropod topology. Therefore, the evolution of different morphological traits, such as one of the most intriguing features of panarthropods-their nervous system-becomes essential for shedding light on the origin and evolution of arthropods and their relatives within the Panarthropoda. In this review, we summarise current knowledge of the evolution of panarthropod nervous and visual systems. In particular, we focus on the evolution of segmental ganglia, the segmental identity of brain regions, and the visual system from morphological and developmental perspectives. In so doing, we address some of the many controversies surrounding these topics, such as the homology of the onychophoran eyes to those of arthropods as well as the segmentation of the tardigrade brain. Finally, we attempt to reconstruct the most likely state of these systems in the last common ancestors of arthropods and panarthropods based on what is currently known about tardigrades and onychophorans.

Nature, source and function of pigments in tardigrades: in vivo raman imaging of carotenoids in Echiniscus blumi.

PubMed

Bonifacio, Alois; Guidetti, Roberto; Altiero, Tiziana; Sergo, Valter; Rebecchi, Lorena

2012-01-01

Tardigrades are microscopic aquatic animals with remarkable abilities to withstand harsh physical conditions such as dehydration or exposure to harmful highly energetic radiation. The mechanisms responsible for such robustness are presently little known, but protection against oxidative stresses is thought to play a role. Despite the fact that many tardigrade species are variously pigmented, scarce information is available about this characteristic. By applying Raman micro-spectroscopy on living specimens, pigments in the tardigrade Echiniscus blumi are identified as carotenoids, and their distribution within the animal body is visualized. The dietary origin of these pigments is demonstrated, as well as their presence in the eggs and in eye-spots of these animals, together with their absence in the outer layer of the animal (i.e., cuticle and epidermis). Using in-vivo semi-quantitative Raman micro-spectroscopy, a decrease in carotenoid content is detected after inducing oxidative stress, demonstrating that this approach can be used for studying the role of carotenoids in oxidative stress-related processes in tardigrades. This approach could be thus used in further investigations to test several hypotheses concerning the function of these carotenoids in tardigrades as photo-protective pigments against ionizing radiations or as antioxidants defending these organisms against the oxidative stress occurring during desiccation processes.

Detection of a troponin I-like protein in non-striated muscle of the tardigrades (water bears)

PubMed Central

Obinata, Takashi; Ono, Kanako

2011-01-01

Tardigrades, also known as water bears, have somatic muscle fibers that are responsible for movement of their body and legs. These muscle fibers contain thin and thick filaments in a non-striated pattern. However, the regulatory mechanism of muscle contraction in tardigrades is unknown. In the absence of extensive molecular and genomic information, we detected a protein of 31 kDa in whole lysates of tardigrades that cross-reacted with the antibody raised against nematode troponin I (TnI). TnI is a component of the troponin complex that regulates actin-myosin interaction in a Ca2+-dependent and actin-linked manner. This TnI-like protein was co-extracted with actin in a buffer containing ATP and EGTA, which is known to induce relaxation of a troponin-regulated contractile system. The TnI-like protein was specifically expressed in the somatic muscle fibers in adult animals and partially co-localized with actin filaments in a non-striated manner. Interestingly, the pharyngeal muscle did not express this protein. These observations suggest that the non-striated somatic muscle of tardigrades has an actin-linked and troponin-regulated system for muscle contraction. PMID:21866271

Evaluation of cryoanalysis as a tool for analyzing elemental distribution in "live" tardigrades using micro-PIXE

NASA Astrophysics Data System (ADS)

Nilsson, E. J. C.; Pallon, J.; Przybylowicz, W. J.; Wang, Y. D.; Jönsson, K. I.

2014-08-01

Although heavy on labor and equipment, thus not often applied, cryoanalysis of frozen hydrated biological specimens can provide information that better reflects the living state of the organism, compared with analysis in the freeze-dried state. In this paper we report a study where the cryoanalysis facility with cryosectioning capabilities at Materials Research Department, iThemba LABS, South Africa was employed to evaluate the usefulness of combining three ion beam analytical methods (μPIXE, RBS and STIM) to analyze a biological target where a better elemental compositional description is needed - the tardigrade. Imaging as well as quantification results are of interest. In a previous study, the element composition and redistribution of elements in the desiccated and active states of two tardigrade species was investigated. This study included analysis of both whole and sectioned tardigrades, and the aim was to analyze each specimen twice; first frozen hydrated and later freeze-dried. The combination of the three analytical techniques proved useful: elements from C to Rb in the tardigrades could be determined and certain differences in distribution of elements between the frozen hydrated and the freeze-dried states were observed. RBS on frozen hydrated specimens provided knowledge of matrix elements.

Structural insights into a secretory abundant heat-soluble protein from an anhydrobiotic tardigrade, Ramazzottius varieornatus.

PubMed

Fukuda, Yohta; Miura, Yoshimasa; Mizohata, Eiichi; Inoue, Tsuyoshi

2017-08-01

Upon stopping metabolic processes, some tardigrades can undergo anhydrobiosis. Secretory abundant heat-soluble (SAHS) proteins have been reported as candidates for anhydrobiosis-related proteins in tardigrades, which seem to protect extracellular components and/or secretory organelles. We determined structures of a SAHS protein from Ramazzottius varieornatus (RvSAHS1), which is one of the toughest tardigrades. RvSAHS1 shows a β-barrel structure similar to fatty acid-binding proteins (FABPs), in which hydrophilic residues form peculiar hydrogen bond networks, which would provide RvSAHS1 with better tolerance against dehydration. We identified two putative ligand-binding sites: one that superimposes on those of some FABPs and the other, unique to and conserved in SAHS proteins. These results indicate that SAHS proteins constitute a new FABP family. © 2017 Federation of European Biochemical Societies.

Tardigrades living in extreme environments have naturally selected prerequisites useful to space conquer

NASA Astrophysics Data System (ADS)

Guidetti, Roberto; Tiziana, Altiero; Cesari, Michele; Rizzo, Angela Maria; Bertolani, Roberto; Galletta, Giuseppe; Dalessandro, Maurizio; Rebecchi, Lorena

Extreme habitats are highly selective and can host only living organisms possessing specific adaptations to stressors. Among extreme habitats, space environment has particular charac-teristics of radiations, vacuum, microgravity and temperature, which induce rapid changes in living systems. Consequently, the response of multicellular complex organisms, able to colo-nize extreme environments, to space stresses can give very useful information on the ability to withstand a single stress or stress combinations. This knowledge on changes in living systems in space, with their similarity to the ageing processes, offers the opportunity to improve human life both on Earth and in space. Even though experimentation in space has often been carried out using unicellular organisms, multicellular organisms are very relevant in order to develop the appropriate countermeasures to avoid the risks imposed by environmental space in humans. The little attention received by multicellular organisms is probably due, other than to difficul-ties in the manipulation of biological materials in space, to the presence of only few organisms with the potential to tolerate environmental space stresses. Among them, tardigrades are small invertebrates representing an attractive animal model to study adaptive strategies for surviving extreme environments, including space environment. Tardigrades are little known microscopic aquatic animals (250-800 m in body length) distributed in different environments (from the deep sea to high mountains and deserts all over the world), and frequently inhabiting very unstable and unpredictable habitats (e.g. interstices of mosses, lichens, leaf litter, freshwater ponds, cryoconite holes). Their ability to live in the extreme environments is related to a wide variety of their life histories and adaptive strategies. A widespread and crucial strategy is cryptobiosis, a form of quiescence. It includes strategies such as anhydrobiosis and cryobiosis, characterized by

Tolerance of anhydrobiotic eggs of the Tardigrade Ramazzottius varieornatus to extreme environments.

PubMed

Horikawa, Daiki D; Yamaguchi, Ayami; Sakashita, Tetsuya; Tanaka, Daisuke; Hamada, Nobuyuki; Yukuhiro, Fumiko; Kuwahara, Hirokazu; Kunieda, Takekazu; Watanabe, Masahiko; Nakahara, Yuichi; Wada, Seiichi; Funayama, Tomoo; Katagiri, Chihiro; Higashi, Seigo; Yokobori, Shin-Ichi; Kuwabara, Mikinori; Rothschild, Lynn J; Okuda, Takashi; Hashimoto, Hirofumi; Kobayashi, Yasuhiko

2012-04-01

Tardigrades are tiny (less than 1 mm in length) invertebrate animals that have the potential to survive travel to other planets because of their tolerance to extreme environmental conditions by means of a dry ametabolic state called anhydrobiosis. While the tolerance of adult tardigrades to extreme environments has been reported, there are few reports on the tolerance of their eggs. We examined the ability of hydrated and anhydrobiotic eggs of the tardigrade Ramazzottius varieornatus to hatch after exposure to ionizing irradiation (helium ions), extremely low and high temperatures, and high vacuum. We previously reported that there was a similar pattern of tolerance against ionizing radiation between hydrated and anhydrobiotic adults. In contrast, anhydrobiotic eggs (50% lethal dose; 1690 Gy) were substantially more radioresistant than hydrated ones (50% lethal dose; 509 Gy). Anhydrobiotic eggs also have a broader temperature resistance compared with hydrated ones. Over 70% of the anhydrobiotic eggs treated at either -196°C or +50°C hatched successfully, but all the hydrated eggs failed to hatch. After exposure to high-vacuum conditions (5.3×10(-4) Pa to 6.2×10(-5) Pa), the hatchability of the anhydrobiotic eggs was comparable to that of untreated control eggs.

Aggregation effects on anhydrobiotic survival in the tardigrade Richtersius coronifer.

PubMed

Ivarsson, Helen; Jönsson, K Ingemar

2004-02-01

For anhydrobiotic metazoans the rate of desiccation is an important factor influencing the probability of survival in a dry anhydrobiotic state. Formation of animal aggregations, in which the exposed body surface area of individual animals is reduced, represents one way to reduce the rate of evaporation. Such aggregations have earlier been documented in e.g., nematodes. We experimentally evaluate the effect of aggregation size (number of animals in a group of desiccating animals) on anhydrobiotic survival in the eutardigrade Richtersius coronifer. The experiment shows that aggregation provides a clear improvement on anhydrobiotic survival. The most likely explanation for this is that aggregated animals were exposed to a lower rate of desiccation. Although the empirical evidence of aggregation in tardigrades is scarce, our study suggests that aggregation could potentially be an important survival factor for tardigrades living in environments characterized by periods of rapid desiccation. Copyright 2004 Wiley-Liss, Inc.

Neutron Dose and Sub-Kelvin Resistance of the Tardigrade: Ramazzottius Varieoranatus

NASA Astrophysics Data System (ADS)

Kletetschka, G.; Horikawa, D.; Parsons, A.; Bodnarik, J.; Chervenak, J.

2010-04-01

Tardigrades have never been exposed to neutron/gamma radiation. They were also never cooled down to temperatures less than 1 K. We will show the survival data of these conditions and discuss the survival mechanisms.

Brain anatomy of the marine tardigrade Actinarctus doryphorus (Arthrotardigrada).

PubMed

Persson, Dennis K; Halberg, Kenneth A; Jørgensen, Aslak; Møbjerg, Nadja; Kristensen, Reinhardt M

2014-02-01

Knowledge of tardigrade brain structure is important for resolving the phylogenetic relationships of Tardigrada. Here, we present new insight into the morphology of the brain in a marine arthrotardigrade, Actinarctus doryphorus, based on transmission electron microscopy, supported by scanning electron microscopy, conventional light microscopy as well as confocal laser scanning microscopy. Arthrotardigrades contain a large number of plesiomorphic characters and likely represent ancestral tardigrades. They often have segmented body outlines and each trunk segment, with its paired set of legs, may have up to five sensory appendages. Noticeably, the head carries numerous cephalic appendages that are structurally equivalent to the sensory appendages of the trunk segments. Our data reveal that the brain of A. doryphorus is partitioned into three paired lobes, and that these lobes exhibit a more pronounced separation as compared to that of eutardigrades. The first brain lobe in A. doryphorus is located anteriodorsally, with the second lobe just below it in an anterioventral position. Both of these two paired lobes are located anterior to the buccal tube. The third pair of brain lobes are situated posterioventrally to the first two lobes, and flank the buccal tube. In addition, A. doryphorus possesses a subpharyngeal ganglion, which is connected with the first of the four ventral trunk ganglia. The first and second brain lobes in A. doryphorus innervate the clavae and cirri of the head. The innervations of these structures indicate a homology between, respectively, the clavae and cirri of A. doryphorus and the temporalia and papilla cephalica of eutardigrades. The third brain lobes innervate the buccal lamella and the stylets as described for eutardigrades. Collectively, these findings suggest that the head region of extant tardigrades is the result of cephalization of multiple segments. Our results on the brain anatomy of Actinarctus doryphorus support the monophyly of

Effect of ultra-high pressure on small animals, tardigrades and Artemia

NASA Astrophysics Data System (ADS)

Ono, Fumihisa; Mori, Yoshihisa; Takarabe, Kenichi; Fujii, Akiko; Saigusa, Masayuki; Matsushima, Yasushi; Yamazaki, Daisuke; Ito, Eiji; Galas, Simon; Saini, Naurang L.

2016-12-01

This research shows that small animals, tardigrades (Milnesium tardigradum) in tun (dehydrated) state and Artemia salina cists (dried eggs) can tolerate the very high hydrostatic pressure of 7.5 GPa. It was really surprising that living organisms can survive after exposure to such a high pressure. We extended these studies to the extremely high pressure of 20 GPa by using a Kawai-type octahedral anvil press. After exposure to this pressure for 30 min, the tardigrades were soaked in pure water and investigated under a microscope. Their bodies regained metabolic state and no serious injury could be seen. But they were not alive. A few of Artemia eggs went part of the way to hatching after soaked in sea water, but they never grew any further. Comparing with the case of blue-green alga, these animals are weaker under ultra-high pressure.

Establishment of a Rearing System of the Extremotolerant Tardigrade Ramazzottius varieornatus: A New Model Animal for Astrobiology

NASA Astrophysics Data System (ADS)

Horikawa, Daiki D.; Kunieda, Takekazu; Abe, Wataru; Watanabe, Masahiko; Nakahara, Yuichi; Yukuhiro, Fumiko; Sakashita, Tetsuya; Hamada, Nobuyuki; Wada, Seiichi; Funayama, Tomoo; Katagiri, Chihiro; Kobayashi, Yasuhiko; Higashi, Seigo

2008-06-01

Studies on the ability of multicellular organisms to tolerate specific environmental extremes are relatively rare compared to those of unicellular microorganisms in extreme environments. Tardigrades are extremotolerant animals that can enter an ametabolic dry state called anhydrobiosis and have high tolerance to a variety of extreme environmental conditions, particularly while in anhydrobiosis. Although tardigrades have been expected to be a potential model animal for astrobiological studies due to their excellent anhydrobiotic and extremotolerant abilities, few studies of tolerance with cultured tardigrades have been reported, possibly due to the absence of a model species that can be easily maintained under rearing conditions. We report the successful rearing of the herbivorous tardigrade, Ramazzottius varieornatus, by supplying the green alga Chlorella vulgaris as food. The life span was 35 ± 16.4 d, deposited eggs required 5.7 ± 1.1 d to hatch, and animals began to deposit eggs 9 d after hatching. The reared individuals of this species had an anhydrobiotic capacity throughout their life cycle in egg, juvenile, and adult stages. Furthermore, the reared adults in an anhydrobiotic state were tolerant of temperatures of 90°C and -196°C, and exposure to 99.8% acetonitrile or irradiation with 4000 Gy 4He ions. Based on their life history traits and tolerance to extreme stresses, R. varieornatus may be a suitable model for astrobiological studies of multicellular organisms.

Suggested Involvement of PP1/PP2A Activity and De Novo Gene Expression in Anhydrobiotic Survival in a Tardigrade, Hypsibius dujardini, by Chemical Genetic Approach.

PubMed

Kondo, Koyuki; Kubo, Takeo; Kunieda, Takekazu

2015-01-01

Upon desiccation, some tardigrades enter an ametabolic dehydrated state called anhydrobiosis and can survive a desiccated environment in this state. For successful transition to anhydrobiosis, some anhydrobiotic tardigrades require pre-incubation under high humidity conditions, a process called preconditioning, prior to exposure to severe desiccation. Although tardigrades are thought to prepare for transition to anhydrobiosis during preconditioning, the molecular mechanisms governing such processes remain unknown. In this study, we used chemical genetic approaches to elucidate the regulatory mechanisms of anhydrobiosis in the anhydrobiotic tardigrade, Hypsibius dujardini. We first demonstrated that inhibition of transcription or translation drastically impaired anhydrobiotic survival, suggesting that de novo gene expression is required for successful transition to anhydrobiosis in this tardigrade. We then screened 81 chemicals and identified 5 chemicals that significantly impaired anhydrobiotic survival after severe desiccation, in contrast to little or no effect on survival after high humidity exposure only. In particular, cantharidic acid, a selective inhibitor of protein phosphatase (PP) 1 and PP2A, exhibited the most profound inhibitory effects. Another PP1/PP2A inhibitor, okadaic acid, also significantly and specifically impaired anhydrobiotic survival, suggesting that PP1/PP2A activity plays an important role for anhydrobiosis in this species. This is, to our knowledge, the first report of the required activities of signaling molecules for desiccation tolerance in tardigrades. The identified inhibitory chemicals could provide novel clues to elucidate the regulatory mechanisms underlying anhydrobiosis in tardigrades.

Suggested Involvement of PP1/PP2A Activity and De Novo Gene Expression in Anhydrobiotic Survival in a Tardigrade, Hypsibius dujardini, by Chemical Genetic Approach

PubMed Central

Kondo, Koyuki; Kubo, Takeo; Kunieda, Takekazu

2015-01-01

Upon desiccation, some tardigrades enter an ametabolic dehydrated state called anhydrobiosis and can survive a desiccated environment in this state. For successful transition to anhydrobiosis, some anhydrobiotic tardigrades require pre-incubation under high humidity conditions, a process called preconditioning, prior to exposure to severe desiccation. Although tardigrades are thought to prepare for transition to anhydrobiosis during preconditioning, the molecular mechanisms governing such processes remain unknown. In this study, we used chemical genetic approaches to elucidate the regulatory mechanisms of anhydrobiosis in the anhydrobiotic tardigrade, Hypsibius dujardini. We first demonstrated that inhibition of transcription or translation drastically impaired anhydrobiotic survival, suggesting that de novo gene expression is required for successful transition to anhydrobiosis in this tardigrade. We then screened 81 chemicals and identified 5 chemicals that significantly impaired anhydrobiotic survival after severe desiccation, in contrast to little or no effect on survival after high humidity exposure only. In particular, cantharidic acid, a selective inhibitor of protein phosphatase (PP) 1 and PP2A, exhibited the most profound inhibitory effects. Another PP1/PP2A inhibitor, okadaic acid, also significantly and specifically impaired anhydrobiotic survival, suggesting that PP1/PP2A activity plays an important role for anhydrobiosis in this species. This is, to our knowledge, the first report of the required activities of signaling molecules for desiccation tolerance in tardigrades. The identified inhibitory chemicals could provide novel clues to elucidate the regulatory mechanisms underlying anhydrobiosis in tardigrades. PMID:26690982

First evidence of epithelial transport in tardigrades: a comparative investigation of organic anion transport.

PubMed

Halberg, Kenneth Agerlin; Møbjerg, Nadja

2012-02-01

We investigated transport of the organic anion Chlorophenol Red (CPR) in the tardigrade Halobiotus crispae using a new method for quantifying non-fluorescent dyes. We compared the results acquired from the tardigrade with CPR transport data obtained from Malpighian tubules of the desert locust Schistocerca gregaria. CPR accumulated in the midgut lumen of H. crispae, indicating that organic anion transport takes place here. Our results show that CPR transport is inhibited by the mitochondrial un-coupler DNP (1 mmol l(-1); 81% reduction), the Na(+)/K(+)-ATPase inhibitor ouabain (10 mmol l(-1); 21% reduction) and the vacuolar H(+)-ATPase inhibitor bafilomycin (5 μmol l(-1); 21% reduction), and by the organic anions PAH (10 mmol l(-1); 44% reduction) and probenecid (10 mmol l(-1); 61% reduction, concentration-dependent inhibition). Transport by locust Malpighian tubules exhibits a similar pharmacological profile, albeit with markedly higher concentrations of CPR being reached in S. gregaria. Immunolocalization of the Na(+)/K(+)-ATPase α-subunit in S. gregaria revealed that this transporter is abundantly expressed and localized to the basal cell membranes. Immunolocalization data could not be obtained from H. crispae. Our results indicate that organic anion secretion by the tardigrade midgut is transporter mediated with likely candidates for the basolateral entry step being members of the Oat and/or Oatp transporter families. From our results, we cautiously suggest that apical H(+) and possibly basal Na(+)/K(+) pumps provide the driving force for the transport; the exact coupling between electrochemical gradients generated by the pumps and transport of ions, as well as the nature of the apical exit step, are unknown. This study is, to our knowledge, the first to show active epithelial transport in tardigrades.

External morphogenesis of the tardigrade Hypsibius dujardini as revealed by scanning electron microscopy.

PubMed

Gross, Vladimir; Minich, Irene; Mayer, Georg

2017-04-01

Tardigrada, commonly called water bears, is a taxon of microscopic panarthropods with five-segmented bodies and four pairs of walking legs. Although tardigrades have been known to science for several centuries, questions remain regarding many aspects of their biology, such as embryogenesis. Herein, we used scanning electron microscopy to document the external changes that occur during embryonic development in the tardigrade Hypsibius dujardini (Eutardigrada, Parachela, Hypsibiidae). Our results show an accelerated development of external features, with approximately 30 hrs separating the point at which external structures first become recognizable and a fully formed embryo. All segments appear to arise simultaneously between ∼20 and 25 hrs of development, and no differences in the degree of development could be detected between the limb buds at any stage. Claws emerge shortly after the limb buds and are morphologically similar to those of adults. The origin of the claws is concurrent with that of the sclerotized parts of the mouth, suggesting that all cuticular structures arise simultaneously at ∼30 hrs. The mouth arises as an invagination in the terminal region of the head at ∼25 hrs, closes later in development, and opens again shortly before hatching. The anlagen of the peribuccal lobes arise as one dorsal and one ventral row, each consisting of three lobes, and later form a ring in the late embryo, whereas there is no indication of a labrum anlage at any point during development. Furthermore, we describe limited postembryonic development in the form of cuticular pores that are absent in juveniles but present in adults. This study represents the first scanning electron micrographs of tardigrade embryos, demonstrating the utility of this technique for studying embryogenesis in tardigrades. This work further adds an external morphological perspective to the developmental data already available for H. dujardini, facilitating future comparisons to related

Segmental expression of Pax3/7 and engrailed homologs in tardigrade development.

PubMed

Gabriel, Willow N; Goldstein, Bob

2007-06-01

How morphological diversity arises through evolution of gene sequence is a major question in biology. In Drosophila, the genetic basis for body patterning and morphological segmentation has been studied intensively. It is clear that some of the genes in the Drosophila segmentation program are functioning similarly in certain other taxa, although many questions remain about when these gene functions arose and which taxa use these genes similarly to establish diverse body plans. Tardigrades are an outgroup to arthropods in the Ecdysozoa and, as such, can provide insight into how gene functions have evolved among the arthropods and their close relatives. We developed immunostaining methods for tardigrade embryos, and we used cross-reactive antibodies to investigate the expression of homologs of the pair-rule gene paired (Pax3/7) and the segment polarity gene engrailed in the tardigrade Hypsibius dujardini. We find that in H. dujardini embryos, Pax3/7 protein localizes not in a pair-rule pattern but in a segmentally iterated pattern, after the segments are established, in regions of the embryo where neurons later arise. Engrailed protein localizes in the posterior ectoderm of each segment before ectodermal segmentation is apparent. Together with previous results from others, our data support the conclusions that the pair-rule function of Pax3/7 is specific to the arthropods, that some of the ancient functions of Pax3/7 and Engrailed in ancestral bilaterians may have been in neurogenesis, and that Engrailed may have a function in establishing morphological boundaries between segments that is conserved at least among the Panarthropoda.

No evidence for extensive horizontal gene transfer in the genome of the tardigrade Hypsibius dujardini

PubMed Central

Koutsovoulos, Georgios; Laetsch, Dominik R.; Stevens, Lewis; Daub, Jennifer; Conlon, Claire; Maroon, Habib; Thomas, Fran; Aboobaker, Aziz A.

2016-01-01

Tardigrades are meiofaunal ecdysozoans that are key to understanding the origins of Arthropoda. Many species of Tardigrada can survive extreme conditions through cryptobiosis. In a recent paper [Boothby TC, et al. (2015) Proc Natl Acad Sci USA 112(52):15976–15981], the authors concluded that the tardigrade Hypsibius dujardini had an unprecedented proportion (17%) of genes originating through functional horizontal gene transfer (fHGT) and speculated that fHGT was likely formative in the evolution of cryptobiosis. We independently sequenced the genome of H. dujardini. As expected from whole-organism DNA sampling, our raw data contained reads from nontarget genomes. Filtering using metagenomics approaches generated a draft H. dujardini genome assembly of 135 Mb with superior assembly metrics to the previously published assembly. Additional microbial contamination likely remains. We found no support for extensive fHGT. Among 23,021 gene predictions we identified 0.2% strong candidates for fHGT from bacteria and 0.2% strong candidates for fHGT from nonmetazoan eukaryotes. Cross-comparison of assemblies showed that the overwhelming majority of HGT candidates in the Boothby et al. genome derived from contaminants. We conclude that fHGT into H. dujardini accounts for at most 1–2% of genes and that the proposal that one-sixth of tardigrade genes originate from functional HGT events is an artifact of undetected contamination. PMID:27035985

No evidence for extensive horizontal gene transfer in the genome of the tardigrade Hypsibius dujardini.

PubMed

Koutsovoulos, Georgios; Kumar, Sujai; Laetsch, Dominik R; Stevens, Lewis; Daub, Jennifer; Conlon, Claire; Maroon, Habib; Thomas, Fran; Aboobaker, Aziz A; Blaxter, Mark

2016-05-03

Tardigrades are meiofaunal ecdysozoans that are key to understanding the origins of Arthropoda. Many species of Tardigrada can survive extreme conditions through cryptobiosis. In a recent paper [Boothby TC, et al. (2015) Proc Natl Acad Sci USA 112(52):15976-15981], the authors concluded that the tardigrade Hypsibius dujardini had an unprecedented proportion (17%) of genes originating through functional horizontal gene transfer (fHGT) and speculated that fHGT was likely formative in the evolution of cryptobiosis. We independently sequenced the genome of H. dujardini As expected from whole-organism DNA sampling, our raw data contained reads from nontarget genomes. Filtering using metagenomics approaches generated a draft H. dujardini genome assembly of 135 Mb with superior assembly metrics to the previously published assembly. Additional microbial contamination likely remains. We found no support for extensive fHGT. Among 23,021 gene predictions we identified 0.2% strong candidates for fHGT from bacteria and 0.2% strong candidates for fHGT from nonmetazoan eukaryotes. Cross-comparison of assemblies showed that the overwhelming majority of HGT candidates in the Boothby et al. genome derived from contaminants. We conclude that fHGT into H. dujardini accounts for at most 1-2% of genes and that the proposal that one-sixth of tardigrade genes originate from functional HGT events is an artifact of undetected contamination.

Analysis of DNA repair and protection in the Tardigrade Ramazzottius varieornatus and Hypsibius dujardini after exposure to UVC radiation.

PubMed

Horikawa, Daiki D; Cumbers, John; Sakakibara, Iori; Rogoff, Dana; Leuko, Stefan; Harnoto, Raechel; Arakawa, Kazuharu; Katayama, Toshiaki; Kunieda, Takekazu; Toyoda, Atsushi; Fujiyama, Asao; Rothschild, Lynn J

2013-01-01

Tardigrades inhabiting terrestrial environments exhibit extraordinary resistance to ionizing radiation and UV radiation although little is known about the mechanisms underlying the resistance. We found that the terrestrial tardigrade Ramazzottius varieornatus is able to tolerate massive doses of UVC irradiation by both being protected from forming UVC-induced thymine dimers in DNA in a desiccated, anhydrobiotic state as well as repairing the dimers that do form in the hydrated animals. In R. varieornatus accumulation of thymine dimers in DNA induced by irradiation with 2.5 kJ/m(2) of UVC radiation disappeared 18 h after the exposure when the animals were exposed to fluorescent light but not in the dark. Much higher UV radiation tolerance was observed in desiccated anhydrobiotic R. varieornatus compared to hydrated specimens of this species. On the other hand, the freshwater tardigrade species Hypsibius dujardini that was used as control, showed much weaker tolerance to UVC radiation than R. varieornatus, and it did not contain a putative phrA gene sequence. The anhydrobiotes of R. varieornatus accumulated much less UVC-induced thymine dimers in DNA than hydrated one. It suggests that anhydrobiosis efficiently avoids DNA damage accumulation in R. varieornatus and confers better UV radiation tolerance on this species. Thus we propose that UV radiation tolerance in tardigrades is due to the both high capacities of DNA damage repair and DNA protection, a two-pronged survival strategy.

Analysis of DNA Repair and Protection in the Tardigrade Ramazzottius varieornatus and Hypsibius dujardini after Exposure to UVC Radiation

PubMed Central

Horikawa, Daiki D.; Cumbers, John; Sakakibara, Iori; Rogoff, Dana; Leuko, Stefan; Harnoto, Raechel; Arakawa, Kazuharu; Katayama, Toshiaki; Kunieda, Takekazu; Toyoda, Atsushi; Fujiyama, Asao; Rothschild, Lynn J.

2013-01-01

Tardigrades inhabiting terrestrial environments exhibit extraordinary resistance to ionizing radiation and UV radiation although little is known about the mechanisms underlying the resistance. We found that the terrestrial tardigrade Ramazzottius varieornatus is able to tolerate massive doses of UVC irradiation by both being protected from forming UVC-induced thymine dimers in DNA in a desiccated, anhydrobiotic state as well as repairing the dimers that do form in the hydrated animals. In R. varieornatus accumulation of thymine dimers in DNA induced by irradiation with 2.5 kJ/m2 of UVC radiation disappeared 18 h after the exposure when the animals were exposed to fluorescent light but not in the dark. Much higher UV radiation tolerance was observed in desiccated anhydrobiotic R. varieornatus compared to hydrated specimens of this species. On the other hand, the freshwater tardigrade species Hypsibius dujardini that was used as control, showed much weaker tolerance to UVC radiation than R. varieornatus, and it did not contain a putative phrA gene sequence. The anhydrobiotes of R. varieornatus accumulated much less UVC-induced thymine dimers in DNA than hydrated one. It suggests that anhydrobiosis efficiently avoids DNA damage accumulation in R. varieornatus and confers better UV radiation tolerance on this species. Thus we propose that UV radiation tolerance in tardigrades is due to the both high capacities of DNA damage repair and DNA protection, a two-pronged survival strategy. PMID:23762256

Effects of ionizing radiation on embryos of the tardigrade Milnesium cf. tardigradum at different stages of development.

PubMed

Beltrán-Pardo, Eliana; Jönsson, K Ingemar; Wojcik, Andrzej; Haghdoost, Siamak; Harms-Ringdahl, Mats; Bermúdez-Cruz, Rosa M; Bernal Villegas, Jaime E

2013-01-01

Tardigrades represent one of the most desiccation and radiation tolerant animals on Earth, and several studies have documented their tolerance in the adult stage. Studies on tolerance during embryological stages are rare, but differential effects of desiccation and freezing on different developmental stages have been reported, as well as dose-dependent effect of gamma irradiation on tardigrade embryos. Here, we report a study evaluating the tolerance of eggs from the eutardigrade Milnesium cf. tardigradum to three doses of gamma radiation (50, 200 and 500 Gy) at the early, middle, and late stage of development. We found that embryos of the middle and late developmental stages were tolerant to all doses, while eggs in the early developmental stage were tolerant only to a dose of 50 Gy, and showed a declining survival with higher dose. We also observed a delay in development of irradiated eggs, suggesting that periods of DNA repair might have taken place after irradiation induced damage. The delay was independent of dose for eggs irradiated in the middle and late stage, possibly indicating a fixed developmental schedule for repair after induced damage. These results show that the tolerance to radiation in tardigrade eggs changes in the course of their development. The mechanisms behind this pattern are unknown, but may relate to changes in mitotic activities over the embryogenesis and/or to activation of response mechanisms to damaged DNA in the course of development.

Effects of Ionizing Radiation on Embryos of the Tardigrade Milnesium cf. tardigradum at Different Stages of Development

PubMed Central

Beltrán-Pardo, Eliana; Jönsson, K. Ingemar; Wojcik, Andrzej; Haghdoost, Siamak; Harms-Ringdahl, Mats; Bermúdez-Cruz, Rosa M.; Bernal Villegas, Jaime E.

2013-01-01

Tardigrades represent one of the most desiccation and radiation tolerant animals on Earth, and several studies have documented their tolerance in the adult stage. Studies on tolerance during embryological stages are rare, but differential effects of desiccation and freezing on different developmental stages have been reported, as well as dose-dependent effect of gamma irradiation on tardigrade embryos. Here, we report a study evaluating the tolerance of eggs from the eutardigrade Milnesium cf. tardigradum to three doses of gamma radiation (50, 200 and 500 Gy) at the early, middle, and late stage of development. We found that embryos of the middle and late developmental stages were tolerant to all doses, while eggs in the early developmental stage were tolerant only to a dose of 50 Gy, and showed a declining survival with higher dose. We also observed a delay in development of irradiated eggs, suggesting that periods of DNA repair might have taken place after irradiation induced damage. The delay was independent of dose for eggs irradiated in the middle and late stage, possibly indicating a fixed developmental schedule for repair after induced damage. These results show that the tolerance to radiation in tardigrade eggs changes in the course of their development. The mechanisms behind this pattern are unknown, but may relate to changes in mitotic activities over the embryogenesis and/or to activation of response mechanisms to damaged DNA in the course of development. PMID:24039737

What can we learn from the toughest animals of the Earth? Water bears (tardigrades) as multicellular model organisms in order to perform scientific preparations for lunar exploration

NASA Astrophysics Data System (ADS)

Guidetti, Roberto; Rizzo, Angela Maria; Altiero, Tiziana; Rebecchi, Lorena

2012-12-01

Space missions of long duration required a series of preliminary experiments on living organisms, validated by a substantial phase of ground simulation experiments, in the field of micro- and inter-mediate gravities, radiobiology, and, for planetary explorations, related to risks deriving from regolith and dust exposure. In this review, we present the tardigrades, whose characteristics that recommend them as an emerging model for space biology. They are microscopic animals but are characterized by a complex structural organization similar to that of larger animals; they can be cultured in lab in small facilities, having small size; they are able to produce clonal lineages by means of parthenogenesis; they can completely suspend their metabolism when entering in dormant states (anhydrobiosis induced by dehydration and cryobiosis induced by freezing); desiccated anhydrobiotic tardigrades are able to withstand chemical and physical extremes, but a large tolerance is showed also by active animals; they can be stored in dry state for many years without loss of viability. Tardigrades have already been exposed to space stressors on Low Earth Orbit several times. The relevance of ground-based and space studies on tardigrades rests on the presumption that results could suggest strategies to protect organisms, also humans, when exposed to the space and lunar environments.

Neuroanatomy of Halobiotus crispae (Eutardigrada: Hypsibiidae): Tardigrade brain structure supports the clade Panarthropoda.

PubMed

Persson, Dennis K; Halberg, Kenneth A; Jørgensen, Aslak; Møbjerg, Nadja; Kristensen, Reinhardt M

2012-11-01

The position of Tardigrada in the animal tree of life is a subject that has received much attention, but still remains controversial. Whereas some think tardigrades should be categorized as cycloneuralians, most authors argue in favor of a phylogenetic position within Panarthropoda as a sister group to Arthropoda or Arthropoda + Onychophora. Thus far, neither molecular nor morphological investigations have provided conclusive results as to the tardigrade sister group relationships. In this article, we present a detailed description of the nervous system of the eutardigrade Halobiotus crispae, using immunostainings, confocal laser scanning microscopy, and computer-aided three-dimensional reconstructions supported by transmission electron microscopy. We report details regarding the structure of the brain as well as the ganglia of the ventral nerve cord. In contrast to the newest investigation, we find transverse commissures in the ventral ganglia, and our data suggest that the brain is partitioned into at least three lobes. Additionally, we can confirm the existence of a subpharyngeal ganglion previously called subesophagal ganglion. According to our results, the original suggestion of a brain comprised of at least three parts cannot be rejected, and the data presented supports a sister group relationship of Tardigrada to 1) Arthropoda or 2) Onychophora or 3) Arthropoda + Onychophora. Copyright © 2012 Wiley Periodicals, Inc.

Can the tardigrade Hypsibius dujardini survive in the absence of the geomagnetic field?

PubMed

Erdmann, Weronika; Idzikowski, Bogdan; Kowalski, Wojciech; Szymański, Bogdan; Kosicki, Jakub Z; Kaczmarek, Łukasz

2017-01-01

Earth's geomagnetic field has undergone critical changes in the past. Studies on the influence of the magnetic field on Earth's organisms are crucial for the understanding of evolution of life on Earth and astrobiological considerations. Numerous studies conducted both on plants and animals confirmed the significant influence of the geomagnetic field on the metabolism of living organisms. Water bears (Tardigrada), which are a mong the most resistant animals due to their cryptobiotic abilities, show significant resistance to a number of environmental stressors, but the influence of the geomagnetic field on their fitness has not been addressed before. In our studies, we used eutardigrade Hypsibius dujardini to analyse whether isolation from the geomagnetic field had an effect on mortality. We found that Hypsibius dujardini specimens demonstrated relatively high mortality during anhydrobiosis, also in control groups exposed to the normal geomagnetic field. Moreover, similar mortality was observed in anhydrobiotic specimens isolated from the geomagnetic field. However, a significant difference was noted between tardigrade survival and the moment of their isolation from the geomagnetic field. In particular, tardigrade mortality substantially increased in absence of a magnetic field during the process of entering anhydrobiosis and returning to active life. Our results suggest that these processes rely on complex metabolic processes that are critically influenced by the geomagnetic field.

Comparative genomics of the tardigrades Hypsibius dujardini and Ramazzottius varieornatus

PubMed Central

Yoshida, Yuki; Koutsovoulos, Georgios; Laetsch, Dominik R.; Stevens, Lewis; Kumar, Sujai; Horikawa, Daiki D.; Ishino, Kyoko; Komine, Shiori; Kunieda, Takekazu; Tomita, Masaru; Blaxter, Mark

2017-01-01

Tardigrada, a phylum of meiofaunal organisms, have been at the center of discussions of the evolution of Metazoa, the biology of survival in extreme environments, and the role of horizontal gene transfer in animal evolution. Tardigrada are placed as sisters to Arthropoda and Onychophora (velvet worms) in the superphylum Panarthropoda by morphological analyses, but many molecular phylogenies fail to recover this relationship. This tension between molecular and morphological understanding may be very revealing of the mode and patterns of evolution of major groups. Limnoterrestrial tardigrades display extreme cryptobiotic abilities, including anhydrobiosis and cryobiosis, as do bdelloid rotifers, nematodes, and other animals of the water film. These extremophile behaviors challenge understanding of normal, aqueous physiology: how does a multicellular organism avoid lethal cellular collapse in the absence of liquid water? Meiofaunal species have been reported to have elevated levels of horizontal gene transfer (HGT) events, but how important this is in evolution, and particularly in the evolution of extremophile physiology, is unclear. To address these questions, we resequenced and reassembled the genome of H. dujardini, a limnoterrestrial tardigrade that can undergo anhydrobiosis only after extensive pre-exposure to drying conditions, and compared it to the genome of R. varieornatus, a related species with tolerance to rapid desiccation. The 2 species had contrasting gene expression responses to anhydrobiosis, with major transcriptional change in H. dujardini but limited regulation in R. varieornatus. We identified few horizontally transferred genes, but some of these were shown to be involved in entry into anhydrobiosis. Whole-genome molecular phylogenies supported a Tardigrada+Nematoda relationship over Tardigrada+Arthropoda, but rare genomic changes tended to support Tardigrada+Arthropoda. PMID:28749982

Comparative genomics of the tardigrades Hypsibius dujardini and Ramazzottius varieornatus.

PubMed

Yoshida, Yuki; Koutsovoulos, Georgios; Laetsch, Dominik R; Stevens, Lewis; Kumar, Sujai; Horikawa, Daiki D; Ishino, Kyoko; Komine, Shiori; Kunieda, Takekazu; Tomita, Masaru; Blaxter, Mark; Arakawa, Kazuharu

2017-07-01

Tardigrada, a phylum of meiofaunal organisms, have been at the center of discussions of the evolution of Metazoa, the biology of survival in extreme environments, and the role of horizontal gene transfer in animal evolution. Tardigrada are placed as sisters to Arthropoda and Onychophora (velvet worms) in the superphylum Panarthropoda by morphological analyses, but many molecular phylogenies fail to recover this relationship. This tension between molecular and morphological understanding may be very revealing of the mode and patterns of evolution of major groups. Limnoterrestrial tardigrades display extreme cryptobiotic abilities, including anhydrobiosis and cryobiosis, as do bdelloid rotifers, nematodes, and other animals of the water film. These extremophile behaviors challenge understanding of normal, aqueous physiology: how does a multicellular organism avoid lethal cellular collapse in the absence of liquid water? Meiofaunal species have been reported to have elevated levels of horizontal gene transfer (HGT) events, but how important this is in evolution, and particularly in the evolution of extremophile physiology, is unclear. To address these questions, we resequenced and reassembled the genome of H. dujardini, a limnoterrestrial tardigrade that can undergo anhydrobiosis only after extensive pre-exposure to drying conditions, and compared it to the genome of R. varieornatus, a related species with tolerance to rapid desiccation. The 2 species had contrasting gene expression responses to anhydrobiosis, with major transcriptional change in H. dujardini but limited regulation in R. varieornatus. We identified few horizontally transferred genes, but some of these were shown to be involved in entry into anhydrobiosis. Whole-genome molecular phylogenies supported a Tardigrada+Nematoda relationship over Tardigrada+Arthropoda, but rare genomic changes tended to support Tardigrada+Arthropoda.

Doryphoribius chetumalensis sp. nov. (Eutardigrada: Isohypsibiidae) a new tardigrade species discovered in an unusual habitat of urban areas of Mexico.

PubMed

Pérez-Pech, Wilbert Andrés; Anguas-Escalante, Abril; Cutz-Pool, Leopoldo Querubin; Guidetti, Roberto

2017-11-07

A new species, Doryphoribius chetumalensis, is described from specimens collected in the city of Chetumal (Quintana Roo state, Mexico). The species was found in a new and unusual habitat for urban tardigrades, i.e. the soil sediment accumulated on the border of streets. This discovery shows that tardigrades can live in this habitat, demonstrating once again the wide capacity of this taxon to tolerate adverse habitats, and to survive in environments with high anthropogenic impact. Doryphoribius chetumalensis sp. nov. differs from all the other species of the genus in having enlarged and wide bulbous base of the claws. Within Doryphoribius, it belongs to the zappalai group, and differs from the species in this group, not only in the claw shape, but also by the orange body colour, the smooth cuticle, the absence of a tooth in the wall of the buccal ring, and the absence of lunules under the claws. This is the first record of tardigrades, identified to species level, in Quintana Roo state. A taxonomic key of the Doryphoribius genus is also presented.

Can the tardigrade Hypsibius dujardini survive in the absence of the geomagnetic field?

PubMed Central

Erdmann, Weronika; Idzikowski, Bogdan; Kowalski, Wojciech; Szymański, Bogdan; Kosicki, Jakub Z.; Kaczmarek, Łukasz

2017-01-01

Earth's geomagnetic field has undergone critical changes in the past. Studies on the influence of the magnetic field on Earth’s organisms are crucial for the understanding of evolution of life on Earth and astrobiological considerations. Numerous studies conducted both on plants and animals confirmed the significant influence of the geomagnetic field on the metabolism of living organisms. Water bears (Tardigrada), which are a mong the most resistant animals due to their cryptobiotic abilities, show significant resistance to a number of environmental stressors, but the influence of the geomagnetic field on their fitness has not been addressed before. In our studies, we used eutardigrade Hypsibius dujardini to analyse whether isolation from the geomagnetic field had an effect on mortality. We found that Hypsibius dujardini specimens demonstrated relatively high mortality during anhydrobiosis, also in control groups exposed to the normal geomagnetic field. Moreover, similar mortality was observed in anhydrobiotic specimens isolated from the geomagnetic field. However, a significant difference was noted between tardigrade survival and the moment of their isolation from the geomagnetic field. In particular, tardigrade mortality substantially increased in absence of a magnetic field during the process of entering anhydrobiosis and returning to active life. Our results suggest that these processes rely on complex metabolic processes that are critically influenced by the geomagnetic field. PMID:28886031

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).

PubMed

Bertolani, Roberto; Bartels, Paul J; Guidetti, Roberto; Cesari, Michele; Nelson, Diane R

2014-02-05

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 morphological 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.

Desiccation tolerance in the tardigrade Richtersius coronifer relies on muscle mediated structural reorganization.

PubMed

Halberg, Kenneth Agerlin; Jørgensen, Aslak; Møbjerg, Nadja

2013-01-01

Life unfolds within a framework of constraining abiotic factors, yet some organisms are adapted to handle large fluctuations in physical and chemical parameters. Tardigrades are microscopic ecdysozoans well known for their ability to endure hostile conditions, such as complete desiccation--a phenomenon called anhydrobiosis. During dehydration, anhydrobiotic animals undergo a series of anatomical changes. Whether this reorganization is an essential regulated event mediated by active controlled processes, or merely a passive result of the dehydration process, has not been clearly determined. Here, we investigate parameters pivotal to the formation of the so-called "tun", a state that in tardigrades and rotifers marks the entrance into anhydrobiosis. Estimation of body volume in the eutardigrade Richtersius coronifer reveals an 87 % reduction in volume from the hydrated active state to the dehydrated tun state, underlining the structural stress associated with entering anhydrobiosis. Survival experiments with pharmacological inhibitors of mitochondrial energy production and muscle contractions show that i) mitochondrial energy production is a prerequisite for surviving desiccation, ii) uncoupling the mitochondria abolishes tun formation, and iii) inhibiting the musculature impairs the ability to form viable tuns. We moreover provide a comparative analysis of the structural changes involved in tun formation, using a combination of cytochemistry, confocal laser scanning microscopy and 3D reconstructions as well as scanning electron microscopy. Our data reveal that the musculature mediates a structural reorganization vital for anhydrobiotic survival, and furthermore that maintaining structural integrity is essential for resumption of life following rehydration.

Desiccation Tolerance in the Tardigrade Richtersius coronifer Relies on Muscle Mediated Structural Reorganization

PubMed Central

Halberg, Kenneth Agerlin; Jørgensen, Aslak; Møbjerg, Nadja

2013-01-01

Life unfolds within a framework of constraining abiotic factors, yet some organisms are adapted to handle large fluctuations in physical and chemical parameters. Tardigrades are microscopic ecdysozoans well known for their ability to endure hostile conditions, such as complete desiccation – a phenomenon called anhydrobiosis. During dehydration, anhydrobiotic animals undergo a series of anatomical changes. Whether this reorganization is an essential regulated event mediated by active controlled processes, or merely a passive result of the dehydration process, has not been clearly determined. Here, we investigate parameters pivotal to the formation of the so-called "tun", a state that in tardigrades and rotifers marks the entrance into anhydrobiosis. Estimation of body volume in the eutardigrade Richtersius coronifer reveals an 87 % reduction in volume from the hydrated active state to the dehydrated tun state, underlining the structural stress associated with entering anhydrobiosis. Survival experiments with pharmacological inhibitors of mitochondrial energy production and muscle contractions show that i) mitochondrial energy production is a prerequisite for surviving desiccation, ii) uncoupling the mitochondria abolishes tun formation, and iii) inhibiting the musculature impairs the ability to form viable tuns. We moreover provide a comparative analysis of the structural changes involved in tun formation, using a combination of cytochemistry, confocal laser scanning microscopy and 3D reconstructions as well as scanning electron microscopy. Our data reveal that the musculature mediates a structural reorganization vital for anhydrobiotic survival, and furthermore that maintaining structural integrity is essential for resumption of life following rehydration. PMID:24391987

Tardigrades from Taiwan, with the description of a new species of Doryphoribius (Tardigrada, Hypsibiidae).

PubMed

Li, Xiaochen; Li, Hongqun

2008-05-01

A total of eleven species of tardigrades from Taiwan are reported in this article. They belong to two classes, three orders, four families, and ten genera. Ten species are new records for Taiwan and one is new to science. Doryphoribius taiwanus sp. nov. is similar to Dor. mariae , but differs from it by larger body size, by conspicuous tubercles on the lateral side and dorsal sides of the body, by lacking gibbosities and undulations, by a narrower buccal tube, and by longer claws.

The tardigrade fauna of Australian marine caves: with descriptions of nine new species of Arthrotardigrada.

PubMed

Jørgensen, Aslak; Boesgaard, Tom M; Møbjerg, Nadja; Kristensen, Reinhardt M

2014-05-28

Marine caves are known to support a rich macrofauna; however, few studies have focused on meiofauna. Marine cave meiofaunal tardigrades have been reported from Japan and the Mediterranean Sea and a preliminary list of species including a redescription of Actinarctus neretinus Grimaldi de Zio, D'Addabbo Gallo, Morone De Lucia, Vaccarella and Grimaldi, 1982 was reported from Fish Rock Cave and Jim's Cave on the coast of Australia. This study is the fourth in a series describing the unique meiofauna in two Australian submarine caves located off the coast of New South Wales, describing nine new species.        Only 67 tardigrades were collected from the two caves, yet these contained a high diversity of at least 16 different species which are quite different in the two caves. The fauna includes nine arthrotardigrade genera: Actinarctus, Batillipes, Dipodarctus, Halechiniscus, Raiarctus, Styraconyx, Tanarctus, Tholoarctus, and Wingstrandarctus. This fauna is different from that reported for the high energy beaches along the East Coast of Australia.        We describe nine new species comprising a single batillipedid and eight halechiniscids: Batillipes solitarius nov. sp., Dipodarctus australiensis nov. sp., Dipodarctus susannae nov. sp., Raiarctus jesperi nov. sp., Raiarctus katrinae nov. sp., Tanarctus hirsutospinosus nov. sp., Tholoarctus oleseni nov. sp., Wingstrandarctus stinae nov. sp. and Wingstrandarctus unsculptus nov. sp.

Analysis of the Opsin Repertoire in the Tardigrade Hypsibius dujardini Provides Insights into the Evolution of Opsin Genes in Panarthropoda

PubMed Central

Hering, Lars; Mayer, Georg

2014-01-01

Screening of a deeply sequenced transcriptome using Illumina sequencing as well as the genome of the tardigrade Hypsibius dujardini revealed a set of five opsin genes. To clarify the phylogenetic position of these genes and to elucidate the evolutionary history of opsins in Panarthropoda (Onychophora + Tardigrada + Arthropoda), we reconstructed the phylogeny of broadly sampled metazoan opsin genes using maximum likelihood and Bayesian inference methods in conjunction with carefully selected substitution models. According to our findings, the opsin repertoire of H. dujardini comprises representatives of all three major bilaterian opsin clades, including one r-opsin, three c-opsins, and a Group 4 opsin (neuropsin/opsin-5). The identification of the tardigrade ortholog of neuropsin/opsin-5 is the first record of this opsin type in a protostome, but our screening of available metazoan genomes revealed that it is also present in other protostomes. Our opsin phylogeny further suggests that two r-opsins, including an “arthropsin,” were present in the last common ancestor of Panarthropoda. Although both r-opsin lineages were retained in Onychophora and Arthropoda, the arthropsin was lost in Tardigrada. The single (most likely visual) r-opsin found in H. dujardini supports the hypothesis of monochromatic vision in the panarthropod ancestor, whereas two duplications of the ancestral panarthropod c-opsin have led to three c-opsins in tardigrades. Although the early-branching nodes are unstable within the metazoans, our findings suggest that the last common ancestor of Bilateria possessed six opsins: Two r-opsins, one c-opsin, and three Group 4 opsins, one of which (Go opsin) was lost in the ecdysozoan lineage. PMID:25193307

Two new tardigrade species from Sicily.

PubMed

Pilato, Giovanni; Sabella, Giorgio; Lisi, Oscar

2014-01-14

Two new species of tardigrades are described from Sicilian moss samples: Macrobiotus insuetus sp. nov. and Diphascon (Diphascon) procerum sp. nov.        Macrobiotus insuetus sp. nov. is a species of the harmsworthi-group characterized by both posterior and anterior claws of the hind legs, which are different in shape from those of the first three leg pairs. The IV claws have extended basal tract where the branches are joined and the secondary branch breaks at near right angle to the primary branch and is clearly shorter than the main branch and the secondary branch of claws I-III. The eggs are not areolated and have conical processes with a reticular ornamentation.        Diphascon (D.) procerum sp. nov. has a delicate cuticular ornamentation of very small tubercles, almost dots; two macroplacoids and septulum are present; thin accessory points are present on the main branches of the slender claws; lunules are absent but the base of the external claws of the hind legs are enlarged and slightly indented; a cuticular bar is present near the internal claw of the first three leg pairs and two cuticular bars are present on the hind legs between the base of the claws and near the base of the anterior claw. 

Analysis of the opsin repertoire in the tardigrade Hypsibius dujardini provides insights into the evolution of opsin genes in panarthropoda.

PubMed

Hering, Lars; Mayer, Georg

2014-09-04

Screening of a deeply sequenced transcriptome using Illumina sequencing as well as the genome of the tardigrade Hypsibius dujardini revealed a set of five opsin genes. To clarify the phylogenetic position of these genes and to elucidate the evolutionary history of opsins in Panarthropoda (Onychophora + Tardigrada + Arthropoda), we reconstructed the phylogeny of broadly sampled metazoan opsin genes using maximum likelihood and Bayesian inference methods in conjunction with carefully selected substitution models. According to our findings, the opsin repertoire of H. dujardini comprises representatives of all three major bilaterian opsin clades, including one r-opsin, three c-opsins, and a Group 4 opsin (neuropsin/opsin-5). The identification of the tardigrade ortholog of neuropsin/opsin-5 is the first record of this opsin type in a protostome, but our screening of available metazoan genomes revealed that it is also present in other protostomes. Our opsin phylogeny further suggests that two r-opsins, including an "arthropsin," were present in the last common ancestor of Panarthropoda. Although both r-opsin lineages were retained in Onychophora and Arthropoda, the arthropsin was lost in Tardigrada. The single (most likely visual) r-opsin found in H. dujardini supports the hypothesis of monochromatic vision in the panarthropod ancestor, whereas two duplications of the ancestral panarthropod c-opsin have led to three c-opsins in tardigrades. Although the early-branching nodes are unstable within the metazoans, our findings suggest that the last common ancestor of Bilateria possessed six opsins: Two r-opsins, one c-opsin, and three Group 4 opsins, one of which (Go opsin) was lost in the ecdysozoan lineage. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

A new tardigrade Doryphoribius maasaimarensis sp. nov. (Eutardigrada: Hypsibiidae) from Kenya.

PubMed

Fontoura, Paulo; Lisi, Oscar; Pilato, Giovanni

2013-01-01

A new tardigrade, Doryphoribius maasaimarensis sp. nov., is described from a moss sample collected in Masai Mara Game Reserve, Kenya. The new species is characterized by having a reticulate dorsal cuticle with small tubercles; nine transverse rows of dorsal gibbosities (configuration IX:4-6-4-6-4-6-4-4-2); pharyngeal bulb with two macroplacoids and no microplacoid; claws with short and thin accessory points; small, smooth lunules under the claws. The new species is most similar to Doryphoribius zyxiglobus (Horning, Schuster & Grigarick, 1978). Both exhibit two macroplacoids, similar cuticular pattern and the same configuration of gibbosities. However, in Doryphoribius maasaimarensis sp. nov. the cuticular tubercles are less close, buccal tube slightly longer with respect to the body length, more gradual curvature of the buccal tube, different claws shape and thinner accessory points.

Population dynamics and vertical distribution of enchytraeids and tardigrades in response to deforestation

NASA Astrophysics Data System (ADS)

Uhía, E.; Briones, M. J. I.

2002-12-01

In order to increase our present knowledge of the potential impacts of deforestation on the soil ecosystem, we investigated the responses of enchytraeid and tardigrade populations to tree harvesting. The study was conducted in an area of ca. 10 ha located at an altitude of approximately 450 m in the surroundings of the University campus (Vigo, Pontevedra, Spain). Pine forest ( Pinus pinaster Aiton), with an average density of 400 trees/ha ranging between 10 and 20 years of age, and some young oaks ( Quercus robur L.) were covering the area. At the end of the summer 1995, approximately 50% of the area was harvested. Soil and animal samples were taken from May 1996 to April 1997 at monthly intervals in both forested and deforested areas. Removal of the trees resulted in a significant effect on enchytraeid population numbers and their response was species-dependent in terms of changes in both population numbers and vertical distribution. Higher mortality rates of enchytraeids were recorded in the absence of trees. August seemed to have been critical for survival of all enchytraeid species as no individuals were found in that month and only a few recovered in the following month. Only Cognettia sphagnetorum showed vertical migration in order to avoid adverse conditions. Tardigrades were more abundant in the deforested areas; their ability to enter in a resistant stage could have enabled them to overcome adverse environmental conditions. It is concluded that harvesting of the trees has changed the soil environment and that differences in moisture and temperature conditions are not sufficient to explain the observed differences. The forest soils contained more organic matter than those in the deforested area and therefore differences in the amount and/or quality of the organic matter could be one of the possible explanations for the observed changes in enchytraeid abundance when the forest is removed.

Arginine kinase from the Tardigrade, Macrobiotus occidentalis: molecular cloning, phylogenetic analysis and enzymatic properties.

PubMed

Uda, Kouji; Ishida, Mikako; Matsui, Tohru; Suzuki, Tomohiko

2010-10-01

Arginine kinase (AK), which catalyzes the reversible transfer of phosphate from ATP to arginine to yield phosphoarginine and ADP, is widely distributed throughout the invertebrates. We determined the cDNA sequence of AK from the tardigrade (water bear) Macrobiotus occidentalis, cloned the sequence into pET30b plasmid, and expressed it in Escherichia coli as a 6x His-tag—fused protein. The cDNA is 1377 bp, has an open reading frame of 1080 bp, and has 5′- and 3′-untranslated regions of 116 and 297 bp, respectively. The open reading frame encodes a 359-amino acid protein containing the 12 residues considered necessary for substrate binding in Limulus AK. This is the first AK sequence from a tardigrade. From fragmented and non-annotated sequences available from DNA databases, we assembled 46 complete AK sequences: 26 from arthropods (including 19 from Insecta), 11 from nematodes, 4 from mollusks, 2 from cnidarians and 2 from onychophorans. No onychophoran sequences have been reported previously. The phylogenetic trees of 104 AKs indicated clearly that Macrobiotus AK (from the phylum Tardigrada) shows close affinity with Epiperipatus and Euperipatoides AKs (from the phylum Onychophora), and therefore forms a sister group with the arthropod AKs. Recombinant 6x His-tagged Macrobiotus AK was successfully expressed as a soluble protein, and the kinetic constants (K(m), K(d), V(ma) and k(cat)) were determined for the forward reaction. Comparison of these kinetic constants with those of AKs from other sources (arthropods, mollusks and nematodes) indicated that Macrobiotus AK is unique in that it has the highest values for k(cat) and K(d)K(m) (indicative of synergistic substrate binding) of all characterized AKs.

Towards decrypting cryptobiosis--analyzing anhydrobiosis in the tardigrade Milnesium tardigradum using transcriptome sequencing.

PubMed

Wang, Chong; Grohme, Markus A; Mali, Brahim; Schill, Ralph O; Frohme, Marcus

2014-01-01

Many tardigrade species are capable of anhydrobiosis; however, mechanisms underlying their extreme desiccation resistance remain elusive. This study attempts to quantify the anhydrobiotic transcriptome of the limno-terrestrial tardigrade Milnesium tardigradum. A prerequisite for differential gene expression analysis was the generation of a reference hybrid transcriptome atlas by assembly of Sanger, 454 and Illumina sequence data. The final assembly yielded 79,064 contigs (>100 bp) after removal of ribosomal RNAs. Around 50% of them could be annotated by SwissProt and NCBI non-redundant protein sequences. Analysis using CEGMA predicted 232 (93.5%) out of the 248 highly conserved eukaryotic genes in the assembly. We used this reference transcriptome for mapping and quantifying the expression of transcripts regulated under anhdydrobiosis in a time-series during dehydration and rehydration. 834 of the transcripts were found to be differentially expressed in a single stage (dehydration/inactive tun/rehydration) and 184 were overlapping in two stages while 74 were differentially expressed in all three stages. We have found interesting patterns of differentially expressed transcripts that are in concordance with a common hypothesis of metabolic shutdown during anhydrobiosis. This included down-regulation of several proteins of the DNA replication and translational machinery and protein degradation. Among others, heat shock proteins Hsp27 and Hsp30c were up-regulated in response to dehydration and rehydration. In addition, we observed up-regulation of ployubiquitin-B upon rehydration together with a higher expression level of several DNA repair proteins during rehydration than in the dehydration stage. Most of the transcripts identified to be differentially expressed had distinct cellular function. Our data suggest a concerted molecular adaptation in M. tardigradum that permits extreme forms of ametabolic states such as anhydrobiosis. It is temping to surmise that the

Towards Decrypting Cryptobiosis—Analyzing Anhydrobiosis in the Tardigrade Milnesium tardigradum Using Transcriptome Sequencing

PubMed Central

Wang, Chong; Grohme, Markus A.; Mali, Brahim; Schill, Ralph O.; Frohme, Marcus

2014-01-01

Background Many tardigrade species are capable of anhydrobiosis; however, mechanisms underlying their extreme desiccation resistance remain elusive. This study attempts to quantify the anhydrobiotic transcriptome of the limno-terrestrial tardigrade Milnesium tardigradum. Results A prerequisite for differential gene expression analysis was the generation of a reference hybrid transcriptome atlas by assembly of Sanger, 454 and Illumina sequence data. The final assembly yielded 79,064 contigs (>100 bp) after removal of ribosomal RNAs. Around 50% of them could be annotated by SwissProt and NCBI non-redundant protein sequences. Analysis using CEGMA predicted 232 (93.5%) out of the 248 highly conserved eukaryotic genes in the assembly. We used this reference transcriptome for mapping and quantifying the expression of transcripts regulated under anhdydrobiosis in a time-series during dehydration and rehydration. 834 of the transcripts were found to be differentially expressed in a single stage (dehydration/inactive tun/rehydration) and 184 were overlapping in two stages while 74 were differentially expressed in all three stages. We have found interesting patterns of differentially expressed transcripts that are in concordance with a common hypothesis of metabolic shutdown during anhydrobiosis. This included down-regulation of several proteins of the DNA replication and translational machinery and protein degradation. Among others, heat shock proteins Hsp27 and Hsp30c were up-regulated in response to dehydration and rehydration. In addition, we observed up-regulation of ployubiquitin-B upon rehydration together with a higher expression level of several DNA repair proteins during rehydration than in the dehydration stage. Conclusions Most of the transcripts identified to be differentially expressed had distinct cellular function. Our data suggest a concerted molecular adaptation in M. tardigradum that permits extreme forms of ametabolic states such as anhydrobiosis. It is

Mesobiotus philippinicus sp. nov., the first limnoterrestrial tardigrade from the Philippines.

PubMed

Mapalo, Marc A; Stec, Daniel; Mirano-Bascos, Denise; Michalczyk, Łukasz

2016-06-20

The limnoterrestrial tardigrade fauna of the Philippines is completely unknown. In this paper, we describe the first ever limnoterrestrial water bear species from this southeast Asian country, Mesobiotus philippinicus sp. nov., found in a moss sample collected in Quezon City. Apart from morphometrics and imaging in light microscopy, we also analysed the new species under scanning electron microscope and sequenced four DNA markers differing in mutation rates, three nuclear (18S rRNA, 28S rRNA, and ITS-2) and one mitochondrial (COI). This allowed not only a detailed description but also provided barcodes to aid future species identification. The new species belongs to the harmsworthi group and is most similar to M. diffusus (Binda & Pilato, 1987), M. pseudocoronatus (Pilato et al., 2006), M. montanus (Murray, 1910) and M. mottai (Binda & Pilato, 1994), but differs from these species by whorled egg processes and dimensions of some morphometric traits. The 28S rRNA, ITS-2 and COI sequences presented in this paper are the first published DNA sequences for the genus Mesobiotus.

Will the Antarctic tardigrade Acutuncus antarcticus be able to withstand environmental stresses related to global climate change?

PubMed

Giovannini, Ilaria; Altiero, Tiziana; Guidetti, Roberto; Rebecchi, Lorena

2018-02-20

Because conditions in continental Antarctica are highly selective and extremely hostile to life, its biota is depauperate, but well adapted to live in this region. Global climate change has the potential to impact continental Antarctic organisms because of increasing temperatures and ultraviolet radiation. This research evaluates how ongoing climate changes will affect Antarctic species, and whether Antarctic organisms will be able to adapt to the new environmental conditions. Tardigrades represent one of the main terrestrial components of Antarctic meiofauna; therefore, the pan-Antarctic tardigrade Acutuncus antarcticus was used as model to predict the fate of Antarctic meiofauna threatened by climate change. Acutuncus antarcticus individuals tolerate events of desiccation, increased temperature and UV radiation. Both hydrated and desiccated animals tolerate increases in UV radiation, even though the desiccated animals are more resistant. Nevertheless, the survivorship of hydrated and desiccated animals is negatively affected by the combination of temperature and UV radiation, with the hydrated animals being more tolerant than desiccated animals. Finally, UV radiation has a negative impact on the life history traits of successive generations of A. antarcticus , causing an increase in egg reabsorption and teratological events. In the long run, A. antarcticus could be at risk of population reductions or even extinction. Nevertheless, because the changes in global climate will proceed gradually and an overlapping of temperature and UV increase could be limited in time, A. antarcticus , as well as many other Antarctic organisms, could have the potential to overcome global warming stresses, and/or the time and capability to adapt to the new environmental conditions. © 2018. Published by The Company of Biologists Ltd.

Distribution of Calcium and Chitin in the Tardigrade Feeding Apparatus in Relation to its Function and Morphology.

PubMed

Guidetti, Roberto; Bonifacio, Alois; Altiero, Tiziana; Bertolani, Roberto; Rebecchi, Lorena

2015-08-01

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, scanning electron microscopy, confocal laser scanning microscopy, energy dispersive X-ray spectroscopy, 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. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

First record of cysts in the tidal tardigrade Echiniscoides sigismundi

NASA Astrophysics Data System (ADS)

Clausen, Lykke K. B.; Andersen, Kasper N.; Hygum, Thomas L.; Jørgensen, Aslak; Møbjerg, Nadja

2014-12-01

Tardigrades are microscopic metazoans that withstand environmental extremes by entering dormant states, such as cryptobiosis (latent life). In addition, they may also form cysts. Here, we present the first report of cyst formation in a marine heterotardigrade, i.e., Echiniscoides sigismundi, which constitutes a cryptic species complex present worldwide in tidal zones. The cysts were initially discovered during experimental series constructed to investigate osmotic stress tolerance. The animals, which eventually formed cysts, showed signs of an imminent molt at the beginning of experimentation. We use the term "cyst" for stages, where a total of three or more cuticles have been synthesized. Our observations show that encystment in E. sigismundi involves synthesizing of at least two new cuticle layers. Legs with discharged claws are present in connection with the first outer cuticle, as well as the second cuticular layer. In the most developed cyst, a third cuticle lacking claws seems to surround the animal, which is delineated by a fourth cuticle. Many features are shared with the well-studied cysts of eutardigrades. The cysts of E. sigismundi, however, lack pigmentation and have an extra set of claws, and the animal inside retains buccopharyngeal sclerified parts, until discharging the third cuticle. The finding of cysts in a marine heterotardigrade is novel and confirms that encystment also occurs within this major evolutionary lineage.

Survival of the Tardigrade Hypsibius Dujardini during Hypervelocity Impact Events up to 5.49 km s-1

NASA Astrophysics Data System (ADS)

Pasini, D.

2014-04-01

Studies have previously been conducted to verify the survivability of living cells during hypervelocity impact events to test the panspermia and lithopanspermia hypotheses [1, 2]. It has been demonstrated that bacteria survive impacts up to 5.4 km s-1 (approx. shock pressure 30 GPa) - albeit with a low probability of survival [1], whilst larger, more complex, objects (such as seeds) break up at ~1 km s-1 [2]. The survivability of yeast spores in impacts up to 7.4 km s-1 has also recently been shown [3]. Previous work by the authors demonstrated the survivability of Nannochloropsis Oculata Phytoplankton, a eukaryotic photosynthesizing autotroph found in the 'euphotic zone' (sunlit surface layers of oceans [4]), at impact velocities up to 6.07 km s-1 [5]. Other groups have also reported that lichens are able to survive shocks in similar pressure ranges [6]. However, whilst many simple single celled organisms have now been shown to survive such impacts (and the associated pressures) as those encountered during the migration of material from one planet to another [1, 3, 5], complex multicellular organisms have either largely not been tested or, those that have been, have not survived the process [2]. Hypsibius dujardini, like most species of tardigrade, are complex organisms composed of approximately 40,000 cells [7]. When humidity decreases they enter a highly dehydrated state known as a 'tun' and can survive extreme temperatures (as low as - 253°C or as high as 151°C), as well as exposure to Xrays and the vacuum of space [7]. Here we test the shock survivability of Hypsibius dujardini by firing a nylon projectile onto a frozen sample of water containing frozen tardigrades using a light gas gun (LGG) [8]. The recovered ice and water were then analysed under an optical microscope to check the viability of any remnant organisms that may have survived impact, and the pressures generated.

Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades.

PubMed

Kletetschka, Gunther; Hruba, Jolana

2015-01-01

Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs.

Tardigrades from Nahuel Huapi National Park (Argentina, South America) with descriptions of two new Macrobiotidae species.

PubMed

Roszkowska, Milena; Stec, Daniel; Ciobanu, Daniel Adrian; Kaczmarek, Łukasz

2016-04-21

In 31 samples of mosses and lichens collected in the Argentinean province of Río Negro, 657 tardigrades, 53 exuviae and 219 free-laid eggs were found. In total, 20 species were identified: Diphascon chilenense, Dip. mitrense, Echiniscus bigranulatus, Ech. corrugicaudatus, Ech. merokensis merokensis, Ech. testudo, Hebesuncus mollispinus, Hypsibius convergens, Macrobiotus cf. anderssoni, Mac. andinus, Mac. kazmierskii, Mac. patagonicus, Mesobiotus szeptyckii, Mes. pseudoblocki sp. nov., Milnesium argentinum, Mil. beatae, Mil. brachyungue, Mil. granulatum, Mopsechiniscus granulosus, Minibiotus pseudostellarus sp. nov. Of the two new species, Mesobiotus pseudoblocki sp. nov. is most similar to Mes. blocki, but it differs mainly by the lack of dentate lunules, smaller eggs and presence of reticular design on egg processes. Minibiotus pseudostellarus sp. nov. is most similar to Min. constellatus, Min. eichhorni, Min. sidereus or Min. vinciguerrae, but it differs from them by the presence of 'pseudo-star'-shaped pores in the dorsal cuticle instead of fully developed 'stars' and by other morphometric characters.

Dissolved Gases and Ice Fracturing During the Freezing of a Multicellular Organism: Lessons from Tardigrades

PubMed Central

Kletetschka, Gunther; Hruba, Jolana

2015-01-01

Abstract Three issues are critical for successful cryopreservation of multicellular material: gases dissolved in liquid, thermal conductivity of the tissue, and localization of microstructures. Here we show that heat distribution is controlled by the gas amount dissolved in liquids and that when changing the liquid into solid, the dissolved gases either form bubbles due to the absence of space in the lattice of solids and/or are migrated toward the concentrated salt and sugar solution at the cost of amount of heat required to be removed to complete a solid-state transition. These factors affect the heat distribution in the organs to be cryopreserved. We show that the gas concentration issue controls fracturing of ice when freezing. There are volumetric changes not only when changing the liquid into solid (volume increases) but also reduction of the volume when reaching lower temperatures (volume decreases). We discuss these issues parallel with observations of the cryosurvivability of multicellular organisms, tardigrades, and discuss their analogy for cryopreservation of large organs. PMID:26309797

A P2X receptor from the tardigrade species Hypsibius dujardini with fast kinetics and sensitivity to zinc and copper.

PubMed

Bavan, Selvan; Straub, Volko A; Blaxter, Mark L; Ennion, Steven J

2009-01-20

Orthologs of the vertebrate ATP gated P2X channels have been identified in Dictyostelium and green algae, demonstrating that the emergence of ionotropic purinergic signalling was an early event in eukaryotic evolution. However, the genomes of a number of animals including Drosophila melanogaster and Caenorhabditis elegans, both members of the Ecdysozoa superphylum, lack P2X-like proteins, whilst other species such as the flatworm Schistosoma mansoni have P2X proteins making it unclear as to what stages in evolution P2X receptors were lost. Here we describe the functional characterisation of a P2X receptor (HdP2X) from the tardigrade Hypsibius dujardini demonstrating that purinergic signalling is preserved in some ecdysozoa. ATP (EC50 approximately 44.5 microM) evoked transient inward currents in HdP2X with millisecond rates of activation and desensitisation. HdP2X is antagonised by pyridoxal-phosphate-6-azophenyl-2',4' disulfonic acid (IC50 15.0 microM) and suramin (IC50 22.6 microM) and zinc and copper inhibit ATP-evoked currents with IC50 values of 62.8 microM and 19.9 microM respectively. Site-directed mutagenesis showed that unlike vertebrate P2X receptors, extracellular histidines do not play a major role in coordinating metal binding in HdP2X. However, H306 was identified as playing a minor role in the actions of copper but not zinc. Ivermectin potentiated responses to ATP with no effect on the rates of current activation or decay. The presence of a P2X receptor in a tardigrade species suggests that both nematodes and arthropods lost their P2X genes independently, as both traditional and molecular phylogenies place the divergence between Nematoda and Arthropoda before their divergence from Tardigrada. The phylogenetic analysis performed in our study also clearly demonstrates that the emergence of the family of seven P2X channels in human and other mammalian species was a relatively recent evolutionary event that occurred subsequent to the split between

A P2X receptor from the tardigrade species Hypsibius dujardini with fast kinetics and sensitivity to zinc and copper

PubMed Central

Bavan, Selvan; Straub, Volko A; Blaxter, Mark L; Ennion, Steven J

2009-01-01

Background Orthologs of the vertebrate ATP gated P2X channels have been identified in Dictyostelium and green algae, demonstrating that the emergence of ionotropic purinergic signalling was an early event in eukaryotic evolution. However, the genomes of a number of animals including Drosophila melanogaster and Caenorhabditis elegans, both members of the Ecdysozoa superphylum, lack P2X-like proteins, whilst other species such as the flatworm Schistosoma mansoni have P2X proteins making it unclear as to what stages in evolution P2X receptors were lost. Here we describe the functional characterisation of a P2X receptor (HdP2X) from the tardigrade Hypsibius dujardini demonstrating that purinergic signalling is preserved in some ecdysozoa. Results ATP (EC50 ~44.5 μM) evoked transient inward currents in HdP2X with millisecond rates of activation and desensitisation. HdP2X is antagonised by pyridoxal-phosphate-6-azophenyl-2',4' disulfonic acid (IC50 15.0 μM) and suramin (IC50 22.6 μM) and zinc and copper inhibit ATP-evoked currents with IC50 values of 62.8 μM and 19.9 μM respectively. Site-directed mutagenesis showed that unlike vertebrate P2X receptors, extracellular histidines do not play a major role in coordinating metal binding in HdP2X. However, H306 was identified as playing a minor role in the actions of copper but not zinc. Ivermectin potentiated responses to ATP with no effect on the rates of current activation or decay. Conclusion The presence of a P2X receptor in a tardigrade species suggests that both nematodes and arthropods lost their P2X genes independently, as both traditional and molecular phylogenies place the divergence between Nematoda and Arthropoda before their divergence from Tardigrada. The phylogenetic analysis performed in our study also clearly demonstrates that the emergence of the family of seven P2X channels in human and other mammalian species was a relatively recent evolutionary event that occurred subsequent to the split between

Tolerance to X-rays and Heavy Ions (Fe, He) in the Tardigrade Richtersius coronifer and the Bdelloid Rotifer Mniobia russeola

NASA Astrophysics Data System (ADS)

Jønsson, K. Ingemar; Wojcik, Andrzej

2017-02-01

The aim of this study was to analyze tolerance to heavy ions in desiccated animals of the eutardigrade Richtersius coronifer and the bdelloid rotifer Mniobia russeola within the STARLIFE project. Both species were exposed to iron (Fe) and helium (He) ions at the Heavy Ion Medical Accelerator in Chiba (HIMAC) in Chiba, Japan, and to X-rays at the German Aerospace Center (DLR) in Cologne, Germany. Results show no effect of Fe and He on viability up to 7 days post-rehydration in both R. coronifer and M. russeola, while X-rays tended to reduce viability in R. coronifer at the highest doses. Mean egg production rate tended to decline with higher doses in R. coronifer for all radiation types, but the pattern was not statistically confirmed. In M. russeola, there was no such tendency for a dose response in egg production rate. These results confirm the previously reported high tolerance to high linear energy transfer (LET) radiation in tardigrades and show for the first time that bdelloid rotifers are also very tolerant to high-LET radiation. These animal phyla represent the most desiccation- and radiation-tolerant animals on Earth and provide excellent eukaryotic models for astrobiological research.

G-Equivalent Acceleration Tolerance in the Eutardigrade Species Hypsibius dujardini.

PubMed

Vasanthan, Tarushika; Alejaldre, Lorea; Hider, Jessica; Patel, Shreya; Husain, Nabiha; Umapathisivam, Bavithra; Stone, Jonathon

2017-01-01

Tardigrades are microscopic organisms renowned for their ability to survive extreme environmental conditions. Tardigrade extreme-tolerance research has centered on the ability to withstand desiccation, low and high temperatures, and high hydrostatic pressure and radiation levels. Tardigrade tolerance to hypergravity, however, has yet to be described. We used the eutardigrade species Hypsibius dujardini to investigate short-term tolerance to g-equivalent accelerations (i.e., mimicking g-forces). Data obtained from specimens centrifuged between 3421g and 16,060g for 1 min inclusively reveal tolerance in an acceleration-dependent relation, with lower survivorship and egg production at higher accelerations. This is the first study to demonstrate tardigrade potential for tolerance to hypergravity and describe expected effects on tardigrade survival and reproduction. These findings will prove to be useful in lithopanspermia research (i.e., viable spread in meteoritic rocks). Key Words: Astrobiology-Extreme tolerance-Hypergravity-Tardigrade. Astrobiology 17, 55-60.

Tolerance to X-rays and Heavy Ions (Fe, He) in the Tardigrade Richtersius coronifer and the Bdelloid Rotifer Mniobia russeola.

PubMed

Jönsson, K Ingemar; Wojcik, Andrzej

2017-02-01

The aim of this study was to analyze tolerance to heavy ions in desiccated animals of the eutardigrade Richtersius coronifer and the bdelloid rotifer Mniobia russeola within the STARLIFE project. Both species were exposed to iron (Fe) and helium (He) ions at the Heavy Ion Medical Accelerator in Chiba (HIMAC) in Chiba, Japan, and to X-rays at the German Aerospace Center (DLR) in Cologne, Germany. Results show no effect of Fe and He on viability up to 7 days post-rehydration in both R. coronifer and M. russeola, while X-rays tended to reduce viability in R. coronifer at the highest doses. Mean egg production rate tended to decline with higher doses in R. coronifer for all radiation types, but the pattern was not statistically confirmed. In M. russeola, there was no such tendency for a dose response in egg production rate. These results confirm the previously reported high tolerance to high linear energy transfer (LET) radiation in tardigrades and show for the first time that bdelloid rotifers are also very tolerant to high-LET radiation. These animal phyla represent the most desiccation- and radiation-tolerant animals on Earth and provide excellent eukaryotic models for astrobiological research. Key Words: Tardigrada-Rotifera-Radiation tolerance-Heavy ions-X-rays. Astrobiology 17, 163-167.

The Shock Response of Space Bears: The Ability of Life to Survive Some of the Most Extreme Environments Known to Man

NASA Astrophysics Data System (ADS)

Painter, Jonathon; Leighs, James; Appleby-Thomas, Gareth; Hazael, Rachael; McMillan, Paul; Kristensen, Reinhardt

2013-06-01

There have been many recent discoveries of life forms living in environments previously thought to be completely uninhabitable. One particularly interesting discovery of this na- ture is the space bear or tardigrade. The name space bear is a colloquialism applied to the tardigrades because of a recent investigation which saw them being exposed to the vacuum of space and intense solar radiation, and surviving. Tardigrades have the ability to dehy- drate themselves, entering a state called cryptobiosis. This state enables them to survive in the vacuum of space. A single stage gas gun has been employed to uniaxially shock load and subsequently recover tardigrades in both regular and cryptobiotic states. Loading histories were calculated via hydrocode modelling. Survival data is presented comparing shocked and control samples for tardigrades both in normal and cryptobiotic states.

G-Equivalent Acceleration Tolerance in the Eutardigrade Species Hypsibius dujardini

NASA Astrophysics Data System (ADS)

Vasanthan, Tarushika; Alejaldre, Lorea; Hider, Jessica; Patel, Shreya; Husain, Nabiha; Umapathisivam, Bavithra; Stone, Jonathon

2017-01-01

Tardigrades are microscopic organisms renowned for their ability to survive extreme environmental conditions. Tardigrade extreme-tolerance research has centered on the ability to withstand desiccation, low and high temperatures, and high hydrostatic pressure and radiation levels. Tardigrade tolerance to hypergravity, however, has yet to be described. We used the eutardigrade species Hypsibius dujardini to investigate short-term tolerance to g-equivalent accelerations (i.e., mimicking g-forces). Data obtained from specimens centrifuged between 3421g and 16,060g for 1 min inclusively reveal tolerance in an acceleration-dependent relation, with lower survivorship and egg production at higher accelerations. This is the first study to demonstrate tardigrade potential for tolerance to hypergravity and describe expected effects on tardigrade survival and reproduction. These findings will prove to be useful in lithopanspermia research (i.e., viable spread in meteoritic rocks).

The coastal marine Tardigrada of the Americas.

PubMed

Miller, William R; Perry, Emma S

2016-06-20

The Western Hemisphere or the New World, also known as the Americas (North, Central and South America, associated islands and included seas) have historically been divided into two Realms, the Nearctic and Neotropical based on terrestrial biogeography. The coasts of these two terrestrial realms are bordered by six marine realms, 14 marine provinces and 67 marine ecoregions. From current literature, a comprehensive list of the marine tardigrade fauna from the Americas is presented. Data on marine tardigrades were obtained from 385 published Records of the Occurrence (RoO) of a species, their location, tidal zone, and the substrates from which they were reported. Authors' identifications were accepted at face value unless subsequently amended. Thirty genera and 82 species or subspecies are reported from the Americas; 49 species are documented from margins of the terrestrial Nearctic realm (North America) and 48 from terrestrial Neotropical realm (South America) with only 17 species occurring in both. We define cosmopolitan distribution for marine tardigrades as occurring in or on the margins of five of the seven oceans, only two species of marine tardigrade meets this standard. From the Americas 39 species have been described as new to science, 32 species appear restricted to the hemisphere. Taxa were assigned to marine ecoregions based on adjacent geopolitical units (country, states, provinces, etc.) described in published records. Although tardigrades have been reported from all six marine realms, they are only known from 21 of the 67 ecoregions. Most marine tardigrade sampling in the Americas has focused on near shore substrate (sand, mud, barnacles); for some species no substrates have been reported. The west coasts of both continents have little or no data about tardigrade presence.

Resistance to Extreme Stresses in the Tardigrada: Experiments on Earth and in Space and Astrobiological Perspectives

NASA Astrophysics Data System (ADS)

Rebecchi, L.; Altiero, T.; Guidetti, R.; Cesari, M.; Rizzo, A. M.; Bertolani, R.

2010-04-01

The ability of tardigrades to enter cryptobiosis al-lows them to resist to extreme stresses: very low or high temperatures, chemicals, high pressure, ionizing and UV radiations This has lead to propose tardigrades as suitable model in space research.

Tolerance to Gamma Radiation in the Marine Heterotardigrade, Echiniscoides sigismundi.

PubMed

Jönsson, K Ingemar; Hygum, Thomas L; Andersen, Kasper N; Clausen, Lykke K B; Møbjerg, Nadja

2016-01-01

Tardigrades belong to the most radiation tolerant animals on Earth, as documented by a number of studies using both low-LET and high-LET ionizing radiation. Previous studies have focused on semi-terrestrial species, which are also very tolerant to desiccation. The predominant view on the reason for the high radiation tolerance among these semi-terrestrial species is that it relies on molecular mechanisms that evolved as adaptations for surviving dehydration. In this study we report the first study on radiation tolerance in a marine tardigrade, Echiniscoides sigismundi. Adult specimens in the hydrated active state were exposed to doses of gamma radiation from 100 to 5000 Gy. The results showed little effect of radiation at 100 and 500 Gy but a clear decline in activity at 1000 Gy and higher. The highest dose survived was 4000 Gy, at which ca. 8% of the tardigrades were active 7 days after irradiation. LD50 in the first 7 days after irradiation was in the range of 1100-1600 Gy. Compared to previous studies on radiation tolerance in semi-terrestrial and limnic tardigrades, Echiniscoides sigismundi seems to have a lower tolerance. However, the species still fits into the category of tardigrades that have high tolerance to both desiccation and radiation, supporting the hypothesis that radiation tolerance is a by-product of adaptive mechanisms to survive desiccation. More studies on radiation tolerance in tardigrade species adapted to permanently wet conditions, both marine and freshwater, are needed to obtain a more comprehensive picture of the patterns of radiation tolerance.

Tolerance to Gamma Radiation in the Marine Heterotardigrade, Echiniscoides sigismundi

PubMed Central

Hygum, Thomas L.; Andersen, Kasper N.; Clausen, Lykke K. B.; Møbjerg, Nadja

2016-01-01

Tardigrades belong to the most radiation tolerant animals on Earth, as documented by a number of studies using both low-LET and high-LET ionizing radiation. Previous studies have focused on semi-terrestrial species, which are also very tolerant to desiccation. The predominant view on the reason for the high radiation tolerance among these semi-terrestrial species is that it relies on molecular mechanisms that evolved as adaptations for surviving dehydration. In this study we report the first study on radiation tolerance in a marine tardigrade, Echiniscoides sigismundi. Adult specimens in the hydrated active state were exposed to doses of gamma radiation from 100 to 5000 Gy. The results showed little effect of radiation at 100 and 500 Gy but a clear decline in activity at 1000 Gy and higher. The highest dose survived was 4000 Gy, at which ca. 8% of the tardigrades were active 7 days after irradiation. LD50 in the first 7 days after irradiation was in the range of 1100–1600 Gy. Compared to previous studies on radiation tolerance in semi-terrestrial and limnic tardigrades, Echiniscoides sigismundi seems to have a lower tolerance. However, the species still fits into the category of tardigrades that have high tolerance to both desiccation and radiation, supporting the hypothesis that radiation tolerance is a by-product of adaptive mechanisms to survive desiccation. More studies on radiation tolerance in tardigrade species adapted to permanently wet conditions, both marine and freshwater, are needed to obtain a more comprehensive picture of the patterns of radiation tolerance. PMID:27997621

Surface enhanced Raman scattering on Tardigrada--towards monitoring and imaging molecular structures in live cryptobiotic organisms.

PubMed

Kneipp, Harald; Møbjerg, Nadja; Jørgensen, Aslak; Bohr, Henrik G; Hélix-Nielsen, Claus; Kneipp, Janina; Kneipp, Katrin

2013-10-01

Tardigrades are microscopic metazoans which are able to survive extreme physical and chemical conditions by entering a stress tolerant state called cryptobiosis. At present, the molecular mechanisms behind cryptobiosis are still poorly understood. We show that surface enhanced Raman scattering supported by plasmonic gold nanoparticles can measure molecular constituents and their local distribution in live tardigrades. Surface enhanced Raman signatures allow to differentiate between two species and indicate molecular structural differences between tardigrades in water and in a dry state. This opens new avenues for exploring cryptobiosis by studying molecular changes in live cryptobiotic organisms. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Radiation tolerance in water bears.

NASA Astrophysics Data System (ADS)

Horikawa, D. D.; Sakashita, T.; Katagiri, C.; Watanabe, M.; Nakahara, Y.; Okuda, T.; Hamada, N.; Wada, S.; Funayama, T.; Kobayashi, Y.

Tardigrades water bears are tiny invertebrates forming a phylum and inhabit various environments on the earth Terrestrial tardigrades enter a form called as anhydrobiosis when the surrounding water disappears Anhyydrobiosis is defined as an ametabolic dry state and followed by recovering their activity when rehydrated Anhydrobiotic tardigrades show incredible tolerance to a variety of extreme environmental conditions such as temperatures -273 r C to 151 r C vacuum high pressure 600 MPa and chemicals that include alcohols and methyl bromide In these views there have been some discussions about their potential for surviving outer space In the present study we demonstrated the survival limit not merely against gamma-rays but against heavy ions in the tardigrade Milnesium tardigradum in order to evaluate the effects of radiations on them The animals were exposure to 500 to 7000 Gy of gamma-rays or 500 to 8000 Gy of heavy ions 4 He in their hydrated or anhydrobiotic state The results showed that both of hydrated and anhydrobiotic animals have high radio-tolerance median lethal dose LD50 48 h of gamma-rays or heavy ions in M tardigradum was more than 4000 Gy indicating that this species is categorized into the most radio-tolerant animals We suggest that tardigrades will be suitable model animals for extremophilic multicellular organisms and may provide a survival strategy in extraterrestrial environments

Inorganic ion composition in Tardigrada: cryptobionts contain a large fraction of unidentified organic solutes.

PubMed

Halberg, Kenneth Agerlin; Larsen, Kristine Wulff; Jørgensen, Aslak; Ramløv, Hans; Møbjerg, Nadja

2013-04-01

Many species of tardigrades are known to tolerate extreme environmental stress, yet detailed knowledge of the mechanisms underlying the remarkable adaptations of tardigrades is still lacking, as are answers to many questions regarding their basic biology. Here, we present data on the inorganic ion composition and total osmotic concentration of five different species of tardigrades (Echiniscus testudo, Milnesium tardigradum, Richtersius coronifer, Macrobiotus cf. hufelandi and Halobiotus crispae) using high-performance liquid chromatography and nanoliter osmometry. Quantification of the ionic content indicates that Na(+) and Cl(-) are the principal inorganic ions in tardigrade fluids, albeit other ions, i.e. K(+), NH4(+), Ca(2+), Mg(2+), F(-), SO4(2-) and PO4(3-) were also detected. In limno-terrestrial tardigrades, the respective ions are concentrated by a large factor compared with that of the external medium (Na(+), ×70-800; K(+), ×20-90; Ca(2+) and Mg(2+), ×30-200; F(-), ×160-1040, Cl(-), ×20-50; PO4(3-), ×700-2800; SO4(2-), ×30-150). In contrast, in the marine species H. crispae, Na(+), Cl(-) and SO4(2-) are almost in ionic equilibrium with (brackish) salt water, while K(+), Ca(2+), Mg(2+) and F(-) are only slightly concentrated (×2-10). An anion deficit of ~120 mEq l(-1) in M. tardigradum and H. crispae indicates the presence of unidentified ionic components in these species. Body fluid osmolality ranges from 361±49 mOsm kg(-1) in R. coronifer to 961±43 mOsm kg(-1) in H. crispae. Concentrations of most inorganic ions are largely identical between active and dehydrated groups of R. coronifer, suggesting that this tardigrade does not lose large quantities of inorganic ions during dehydration. The large osmotic and ionic gradients maintained by both limno-terrestrial and marine species are indicative of a powerful ion-retentive mechanism in Tardigrada. Moreover, our data indicate that cryptobiotic tardigrades contain a large fraction of unidentified

Comparative proteome analysis of Milnesium tardigradum in early embryonic state versus adults in active and anhydrobiotic state.

PubMed

Schokraie, Elham; Warnken, Uwe; Hotz-Wagenblatt, Agnes; Grohme, Markus A; Hengherr, Steffen; Förster, Frank; Schill, Ralph O; Frohme, Marcus; Dandekar, Thomas; Schnölzer, Martina

2012-01-01

Tardigrades have fascinated researchers for more than 300 years because of their extraordinary capability to undergo cryptobiosis and survive extreme environmental conditions. However, the survival mechanisms of tardigrades are still poorly understood mainly due to the absence of detailed knowledge about the proteome and genome of these organisms. Our study was intended to provide a basis for the functional characterization of expressed proteins in different states of tardigrades. High-throughput, high-accuracy proteomics in combination with a newly developed tardigrade specific protein database resulted in the identification of more than 3000 proteins in three different states: early embryonic state and adult animals in active and anhydrobiotic state. This comprehensive proteome resource includes protein families such as chaperones, antioxidants, ribosomal proteins, cytoskeletal proteins, transporters, protein channels, nutrient reservoirs, and developmental proteins. A comparative analysis of protein families in the different states was performed by calculating the exponentially modified protein abundance index which classifies proteins in major and minor components. This is the first step to analyzing the proteins involved in early embryonic development, and furthermore proteins which might play an important role in the transition into the anhydrobiotic state.

Comparative proteome analysis of Milnesium tardigradum in early embryonic state versus adults in active and anhydrobiotic state

PubMed Central

Schokraie, Elham; Warnken, Uwe; Hotz-Wagenblatt, Agnes; Grohme, Markus A.; Hengherr, Steffen; Förster, Frank; Schill, Ralph O.; Frohme, Marcus; Dandekar, Thomas; Schnölzer, Martina

2012-01-01

Tardigrades have fascinated researchers for more than 300 years because of their extraordinary capability to undergo cryptobiosis and survive extreme environmental conditions. However, the survival mechanisms of tardigrades are still poorly understood mainly due to the absence of detailed knowledge about the proteome and genome of these organisms. Our study was intended to provide a basis for the functional characterization of expressed proteins in different states of tardigrades. High-throughput, high-accuracy proteomics in combination with a newly developed tardigrade specific protein database resulted in the identification of more than 3000 proteins in three different states: early embryonic state and adult animals in active and anhydrobiotic state. This comprehensive proteome resource includes protein families such as chaperones, antioxidants, ribosomal proteins, cytoskeletal proteins, transporters, protein channels, nutrient reservoirs, and developmental proteins. A comparative analysis of protein families in the different states was performed by calculating the exponentially modified protein abundance index which classifies proteins in major and minor components. This is the first step to analyzing the proteins involved in early embryonic development, and furthermore proteins which might play an important role in the transition into the anhydrobiotic state. PMID:23029181

Tardigrada and Rotifera from moss microhabitats on a disappearing Ugandan glacier, with the description of a new species of water bear.

PubMed

Zawierucha, Krzysztof; GĄsiorek, Piotr; Buda, Jakub; Uetake, Jun; Janko, Karel; Fontaneto, Diego

2018-03-08

Glaciers and ice sheets are a peculiar biome with characteristic abiotic and biotic components. Mountain glaciers are predicted to decrease their volume and even to melt away within a few decades. Despite the threat of a disappearing biome, the diversity and the role of microscopic animals as consumers at higher trophic levels in the glacial biome still remain largely unknown. In this study, we report data on tardigrades and rotifers found in glacial mosses on Mount Stanley, Uganda, and describe a new tardigrade species. Adropion afroglacialis sp. nov. differs from the most similar species by having granulation on the cuticle, absence of cuticular bars under the claws, and a different macroplacoid length sequence. We also provide a morphological diagnosis for another unknown tardigrade species of the genus Hypsibius. The rotifers belonged to the families Philodinidae and Habrotrochidae. In addition, we discuss the diversity of microinvertebrates and potential role of tardigrades and rotifers on mountain glaciers as top consumers. As for any organism living apparently exclusively in glacial habitats on tropical glaciers, their extinction in the near future is inevitable, possibly before we can even discover their existence.

Re-description of the Arctic tardigrade Tenuibiotus voronkovi (Tumanov, 2007 (Eutardigrada; Macrobiotidea), with the first molecular data for the genus.

PubMed

Zawierucha, Krzysztof; Kolicka, Małgorzata; Kaczmarek, Łukasz

2016-11-24

Tardigrada is phylum of micrometazoans widely distributed throughout the world, because of old descriptions and insufficient morphometric data, many species currently need revision and re-description. Tenuibiotus voronkovi (Tumanov, 2007) is tardigrade previously only recorded from the Svalbard archipelago. This species' original description was based on two individuals with destroyed claws on the fourth pair of legs and a lack of complete morphometric data for buccal tube and claws. In this paper, we present a re-description of T. voronkovi, supplementing the original description using the original paratype and additional material from Svalbard: Spitsbergen, Nordaustlandet and Edgeøya. This species is characterised by two macroplacoids and a microplacoid, claws of Tenuibiotus type, dentate lunules under claw IV, and faint granulation on legs I-III and strong granulation on the legs IV. We include a new morphological description with microphotographs, morphometric, and molecular data (including: mitochondrial cytochrome c oxidase subunit I (COI), internal transcribed spacers (ITS1-5.8S rDNA-ITS2), and nuclear ribosome subunits 28S rRNA and 18S rRNA). These are the first published molecular data for the genus Tenuibiotus Pilato and Lisi, 2011, analysis of which indicated an affiliation of Tenuibiotus to the family Macrobiotidae. We found no differences in body size between individuals from different islands (Nordaustlandet and Edgeøya), but did observe variability in the eggs. After revision of the literature and the published figures, we concluded that Dastych's (1985) report of T. willardi (Pilato, 1976) from Svalbard, was actually T. voronkovi, which has the greater distribution in Svalbard, and other Arctic locations, than previously believed.

Appearance of males in a thelytokous strain of Milnesium cf. tardigradum (Tardigrada).

PubMed

Suzuki, Atsushi C

2008-08-01

Tardigrades are generally gonochoristic. Many moss-dwelling species propagate by parthenogenesis, but heterogony has not yet been found. Milnesium tardigradum, a carnivorous tardigrade, also has both sexes, but males are usually rare and many populations appear to have only parthenogenetic reproduction. Since 2000, I have maintained a thelytokous strain of Milnesium cf. tardigradum that originated from one female. Individuals of this strain were thought to be all females, but here I report that males have emerged in this strain at a very low frequency. This is the first report of the appearance of males in parthenogenetic tardigrades. On the first pair of legs of some individuals, I observed the modified claws characteristic of males of this species. It is unknown whether these males can actually function in sexual reproduction; however, they might allow some possibility of genetic exchange among clonal populations. No environmental factors that generate males were determined.

Partial mitochondrial gene arrangements support a close relationship between Tardigrada and Arthropoda.

PubMed

Ryu, Shi Hyun; Lee, Ji Min; Jang, Kuem-Hee; Choi, Eun Hwa; Park, Shin Ju; Chang, Cheon Young; Kim, Won; Hwang, Ui Wook

2007-12-31

Regions (about 3.7-3.8 kb) of the mitochondrial genomes (rrnL-cox1) of two tardigrades, a heterotardigrade, Batillipes pennaki, and a eutardigrade, Pseudobiotus spinifer, were sequenced and characterized. The gene order in Batillipes was rrnL-V-rrnS-Q-I-M-nad2-W-C-Y-cox1, and in Pseudobiotus it was rrnL-V-rrnS-Q-M-nad2-W-C-Y-cox1. With the exception of the trnI gene, the two tardigrade regions have the same gene content and order. Their gene orders are strikingly similar to that of the chelicerate Limulus polyphemus (rrnL-V-rrnS-CR-I-Q-M-nad2-W-C-Y-cox1), which is considered to be ancestral for arthropods. Although the tardigrades do not have a distinct control region (CR) within this segment, the trnI gene in Pseudobiotus is located between rrnL-trnL1 and trnL2-nad1, and the trnI gene in Batillipes is located between trnQ and trnM. In addition, the 106-bp region between trnQ and trnM in Batillipes not only contains two plausible trnI genes with opposite orientations, but also exhibits some CR-like characteristics. The mitochondrial gene arrangements of 183 other protostomes were compared. 60 (52.2%) of the 115 arthropods examined have the M-nad2-W-C-Y-cox1 arrangement, and 88 (76.5%) the M-nad2-W arrangement, as found in the tardigrades. In contrast, no such arrangement was seen in the 70 non-arthropod protostomes studied. These are the first non-sequence molecular data that support the close relationship of tardigrades and arthropods.

Terrestrial and freshwater Tardigrada of the Americas.

PubMed

Meyer, Harry A

2013-12-16

This paper provides a comprehensive list of the freshwater and terrestrial tardigrade fauna reported from the Americas (North America, South America, Central America and the West Indies), their distribution in the Americas, and the substrates from which they have been reported. Data were obtained from 316 published references. Authors' identifications were accepted at face value unless subsequently amended. Taxa were assigned to sub-national units (states, provinces, etc.). Many areas, in particular large portions of Central America and the West Indies, have no reported tardigrade fauna.        The presence of 54 genera and 380 species has been reported for the Americas; 245 species have been collected in the Nearctic ecozone and 251 in the Neotropical ecozone. Among the tardigrade species found in the Americas, 52 are currently considered cosmopolitan, while 153 species have known distributions restricted to the Americas. Based on recent taxonomic revision of the genus Milnesium, the vast majority of records of M. tardigradum in the Americas should now be reassigned to Milnesium tardigradum sensu lato, either because the provided description differs from M. tardigradum sensu stricto or because insufficient description is provided to make a determination; the remainder should be considered Milnesium cf. tardigradum.        Most terrestrial tardigrade sampling in the Americas has focused on cryptogams (mosses, lichens and liverworts); 90% of the species have been collected in such substrates. The proportion of species collected in other habitats is lower: 14% in leaf litter, 20% in soil, and 24% in aquatic samples (in other terrestrial substrates the proportion never exceeds 5%). Most freshwater tardigrades have been collected from aquatic vegetation and sediment. For nine species in the Americas no substrates have been reported. 

Life history of Milnesium tardigradum Doyère (tardigrada) under a rearing environment.

PubMed

Suzuki, Atsushi C

2003-01-01

A strain of carnivorous tardigrade, Milnesium tardigradum, was reared in water on agar plates at 25 degrees C. The monogonont rotifer Lecane inermis was presented as a food source. This rearing system permitted detailed observation of tardigrade behaviour. Daily measurements of body length allowed the growth rate and moulting cycle of this species to be determined. The life history of M. tardigradum raised under these conditions included up to seven periods of moult. The first and second moults occurred at intervals of 4-5 days, and individuals reached reproductive maturity at the 3rd-instar stage; the first period of egg laying accompanied the third moult. The most rapidly developing animal in the study population laid eggs 12 days after hatching. The egg-laying intervals or moulting intervals of adult animals were around 6-10 days. The mean clutch size was 6.9 eggs. All tardigrades in this laboratory population were female and reproduced by parthenogenesis. The duration of the embryonic stage ranged from 5-16 days. The most long-lived female survived for 58 days after hatching, and laid a total of 41 eggs in 5 separate clutches. The entire life cycle of tardigrades reared under these conditions was recorded and photographed. A brief description of the embryonic development of M. tardigradum was also reported.

Current status of the tardigrada: evolution and ecology.

PubMed

Nelson, Diane R

2002-07-01

The Tardigrada are bilaterally symmetrical micrometazoans with four pairs of lobopod legs terminating in claws or sucking disks. They occupy a diversity of niches in marine, freshwater, and terrestrial environments throughout the world. Some have a cosmopolitan distribution, while others are endemic. About 900 species have been described thus far, but many more species are expected as additional habitats are investigated. Most are less than 1 mm in body length and are opaque or translucent, exhibiting colors such as brown, green, orange, yellow, red, or pink in the cuticle and/or gut. Marine species are more variable in body shape and overall appearance and generally exhibit low population density with high species diversity. Reproductive modes include sexual reproduction and parthenogenesis, but much remains to be known about development. Tardigrades have a hemocoel-type of fluid-filled body cavity, a complete digestive tract, and a lobed dorsal brain with a ventral nerve cord with fused ganglia. Recent molecular analyses and additional morphological studies of the nervous system have confirmed the phylogenetic position of tardigrades as a sister group of the arthropods. The ability of tardigrades to undergo cryptobiosis has long intrigued scientists. Although tardigrades are active only when surrounded by a film of water, they can enter latent states in response to desiccation (anhydrobiosis), temperature (cryobiosis), low oxygen (anoxybiosis), and salinity changes (osmobiosis). Cryptobiotic states aid in dispersal.

Meiofaunal Richness in Highly Acidic Hot Springs in Unzen-Amakusa National Park, Japan, Including the First Rediscovery Attempt for Mesotardigrada.

PubMed

Suzuki, Atsushi C; Kagoshima, Hiroshi; Chilton, Glen; Grothman, Gary T; Johansson, Carl; Tsujimoto, Megumu

2017-02-01

Extreme environments sometimes support surprisingly high meiofaunal diversity. We sampled runoff from the acidic hot springs of Unzen, Japan. This is the type locality of Thermozodium esakii Rahm, 1937, the only tardigrade in the class Mesotardigrada, which remains contentious in the absence of corroboration or supporting specimens. Our sampling revealed at least three species of arthropods, four rotifers, and five nematodes living in the hot (ca. 40°C) and acidic (ca. pH 2.5) water, but no tardigrades.

Gilbert Rahm and the Status of Mesotardigrada Rahm, 1937.

PubMed

Grothman, Gary T; Johansson, Carl; Chilton, Glen; Kagoshima, Hiroshi; Tsujimoto, Megumu; Suzuki, Atsushi C

2017-02-01

The tardigrade class Mesotardigrada was erected on the basis of the description of Thermozodium esakii by Gilbert Rahm in 1937. In some characteristics, T. esakii is intermediate between members of the classes Eutardigrada and Heterotardigrada. The class Mesotardigrada is known only from Rahm's published drawings of T. esakii; no voucher specimens are known, and subsequent attempts to collect it at the locus typicus have been unsuccessful. Among the possible explanations for this situation are that Rahm may have collected specimens of a more typical tardigrade, but misinterpreted what he saw. Alternatively, changes in habitat in the area may have led to the tardigrade's extirpation. Perhaps T. esakii is a rare species, such that recent sampling efforts have been insufficient to rediscover it. Finally, Rahm's 1937 description may be an attempt at deception. Until physical evidence of T. esakii is found, the species, and by extension the class Mesotardigrada, should be considered nomen dubium.

Tardigrada of Ireland: a review of records and an updated checklist of species including a new addition to the Irish fauna.

PubMed

DeMilio, Erica; Lawton, Colin; Marley, Nigel J

2016-01-01

The phylum Tardigrada was not recorded in Ireland until the Clare Island Survey of 1909-1911, with only rare subsequent reports on Irish tardigrade species. In recent decades, significant taxonomic revision has occurred within Tardigrada. This has resulted in the need for a review of all known historical records from Ireland and Northern Ireland in order to produce an updated checklist of valid taxa. The new checklist includes fifty-one tardigrade species and subspecies including a new addition to the Irish fauna reported herein, Echiniscus quadrispinosus quadrispinosus Richters, 1902 from Newtown, Ballyvaughan, Co. Clare.

Integrated pathway modules using time-course metabolic profiles and EST data from Milnesium tardigradum.

PubMed

Beisser, Daniela; Grohme, Markus A; Kopka, Joachim; Frohme, Marcus; Schill, Ralph O; Hengherr, Steffen; Dandekar, Thomas; Klau, Gunnar W; Dittrich, Marcus; Müller, Tobias

2012-06-19

Tardigrades are multicellular organisms, resistant to extreme environmental changes such as heat, drought, radiation and freezing. They outlast these conditions in an inactive form (tun) to escape damage to cellular structures and cell death. Tardigrades are apparently able to prevent or repair such damage and are therefore a crucial model organism for stress tolerance. Cultures of the tardigrade Milnesium tardigradum were dehydrated by removing the surrounding water to induce tun formation. During this process and the subsequent rehydration, metabolites were measured in a time series by GC-MS. Additionally expressed sequence tags are available, especially libraries generated from the active and inactive state. The aim of this integrated analysis is to trace changes in tardigrade metabolism and identify pathways responsible for their extreme resistance against physical stress. In this study we propose a novel integrative approach for the analysis of metabolic networks to identify modules of joint shifts on the transcriptomic and metabolic levels. We derive a tardigrade-specific metabolic network represented as an undirected graph with 3,658 nodes (metabolites) and 4,378 edges (reactions). Time course metabolite profiles are used to score the network nodes showing a significant change over time. The edges are scored according to information on enzymes from the EST data. Using this combined information, we identify a key subnetwork (functional module) of concerted changes in metabolic pathways, specific for de- and rehydration. The module is enriched in reactions showing significant changes in metabolite levels and enzyme abundance during the transition. It resembles the cessation of a measurable metabolism (e.g. glycolysis and amino acid anabolism) during the tun formation, the production of storage metabolites and bioprotectants, such as DNA stabilizers, and the generation of amino acids and cellular components from monosaccharides as carbon and energy source

Tardigrada of Ireland: a review of records and an updated checklist of species including a new addition to the Irish fauna

PubMed Central

DeMilio, Erica; Lawton, Colin; Marley, Nigel J.

2016-01-01

Abstract The phylum Tardigrada was not recorded in Ireland until the Clare Island Survey of 1909–1911, with only rare subsequent reports on Irish tardigrade species. In recent decades, significant taxonomic revision has occurred within Tardigrada. This has resulted in the need for a review of all known historical records from Ireland and Northern Ireland in order to produce an updated checklist of valid taxa. The new checklist includes fifty-one tardigrade species and subspecies including a new addition to the Irish fauna reported herein, Echiniscus quadrispinosus quadrispinosus Richters, 1902 from Newtown, Ballyvaughan, Co. Clare. PMID:27667947

Integrated pathway modules using time-course metabolic profiles and EST data from Milnesium tardigradum

PubMed Central

2012-01-01

Background Tardigrades are multicellular organisms, resistant to extreme environmental changes such as heat, drought, radiation and freezing. They outlast these conditions in an inactive form (tun) to escape damage to cellular structures and cell death. Tardigrades are apparently able to prevent or repair such damage and are therefore a crucial model organism for stress tolerance. Cultures of the tardigrade Milnesium tardigradum were dehydrated by removing the surrounding water to induce tun formation. During this process and the subsequent rehydration, metabolites were measured in a time series by GC-MS. Additionally expressed sequence tags are available, especially libraries generated from the active and inactive state. The aim of this integrated analysis is to trace changes in tardigrade metabolism and identify pathways responsible for their extreme resistance against physical stress. Results In this study we propose a novel integrative approach for the analysis of metabolic networks to identify modules of joint shifts on the transcriptomic and metabolic levels. We derive a tardigrade-specific metabolic network represented as an undirected graph with 3,658 nodes (metabolites) and 4,378 edges (reactions). Time course metabolite profiles are used to score the network nodes showing a significant change over time. The edges are scored according to information on enzymes from the EST data. Using this combined information, we identify a key subnetwork (functional module) of concerted changes in metabolic pathways, specific for de- and rehydration. The module is enriched in reactions showing significant changes in metabolite levels and enzyme abundance during the transition. It resembles the cessation of a measurable metabolism (e.g. glycolysis and amino acid anabolism) during the tun formation, the production of storage metabolites and bioprotectants, such as DNA stabilizers, and the generation of amino acids and cellular components from monosaccharides as carbon and

The Zoogeography of Marine Tardigrada.

PubMed

Kaczmarek, Łukasz; Bartels, Paul J; Roszkowska, Milena; Nelson, Diane R

2015-11-02

This monograph describes the global records of marine water bears (Phylum Tardigrada). We provide a comprehensive list of marine tardigrades recorded from around the world, providing an up-to-date taxonomy and a complete bibliography accompanied by geographic co-ordinates, habitat, substrate and biogeographic comments. A link is provided to an on-line interactive map where all occurrences for each species are shown. In total we list 197 taxa and their 2240 records from 39 oceans and seas and 18 Major Fishing Areas (FAO). It is hoped this work will serve as a reference point and background for further zoogeographic and taxonomic studies on marine tardigrades.

Detection of cell proliferation in adults of the water bear Hypsibius dujardini (Tardigrada) via incorporation of a thymidine analog.

PubMed

Gross, V; Bährle, R; Mayer, G

2018-04-01

The taxon Tardigrada, commonly called "water bears", consists of microscopic, eight-legged invertebrates that are well known for their ability to tolerate extreme environmental conditions. Their miniscule body size means that tardigrades possess a small total number of cells, the number and arrangement of which may be highly conserved in some organs. Although mitoses have been observed in several organs, the rate and pattern of cell divisions in adult tardigrades has never been characterized. In this study, we incubated live tardigrades over a period of several days with a thymidine analog in order to visualize all cells that had divided during this time. We focus on the midgut, the largest part of the digestive system. Our results show that new cells in the midgut arise from the anterior and posterior ends of this organ and either migrate or divide toward its middle. These cells divide at a constant rate and all cells of the midgut epithelium are replaced in approximately one week. On the other hand, we found no cell divisions in the nervous system or any other major organs, suggesting that the cell turnover of these organs may be extremely slow or dependent on changing environmental conditions. Copyright © 2018 Elsevier Ltd. All rights reserved.

The structure of the desiccated Richtersius coronifer (Richters, 1903).

PubMed

Czerneková, Michaela; Jönsson, K Ingemar; Chajec, Lukasz; Student, Sebastian; Poprawa, Izabela

2017-05-01

Tun formation is an essential morphological adaptation for entering the anhydrobiotic state in tardigrades, but its internal structure has rarely been investigated. We present the structure and ultrastructure of organs and cells in desiccated Richtersius coronifer by transmission and scanning electron microscopy, confocal microscopy, and histochemical methods. A 3D reconstruction of the body organization of the tun stage is also presented. The tun formation during anhydrobiosis of tardigrades is a process of anterior-posterior body contraction, which relocates some organs such as the pharyngeal bulb. The cuticle is composed of epicuticle, intracuticle and procuticle; flocculent coat; and trilaminate layer. Moulting does not seem to restrict the tun formation, as evidenced from tardigrade tuns that were in the process of moulting. The storage cells of desiccated specimens filled up the free inner space and surrounded internal organs, such as the ovary and digestive system, which were contracted. All cells (epidermal cells, storage cells, ovary cells, cells of the digestive system) underwent shrinkage, and their cytoplasm was electron dense. Lipids and polysaccharides dominated among reserve material of storage cells, while the amount of protein was small. The basic morphology of specific cell types and organelles did not differ between active and anhydrobiotic R. coronifer.

Phylogenetic position of the enigmatic clawless eutardigrade genus Apodibius Dastych, 1983 (Tardigrada), based on 18S and 28S rRNA sequence data from its type species A. confusus.

PubMed

Dabert, Miroslawa; Dastych, Hieronymus; Hohberg, Karin; Dabert, Jacek

2014-01-01

The systematics of Eutardigrada, the largest lineage among the three classes of the phylum Tardigrada, is based mainly on the morphology of the leg claws and of the buccal apparatus. However, three members of the rarely recorded and poorly known limno-terrestrial eutardigrade genus Apodibius have no claws on their strongly reduced legs, a unique character among all tardigrades. This absence of all claws makes the systematic position of Apodibius one of the most enigmatic among the whole class. Until now all known associates of the genus Apodibius have been located in the incertae sedis species group or, quite recently, included into the Necopinatidae family. In the present study, phylogenetic analyses of 18S and 28S rRNA sequence data from 31 tardigrade species representing four parachelan superfamilies (Isohypsibioidea, Hypsibioidea, Macrobiotoidea, Eohypsibioidea), the apochelan Milnesium tardigradum, and the type species of the genus Apodibius, A. confusus, indicated close relationship of the Apodibius with tardigrade species recently included in the superfamily Isohypsibioidea. This result was well-supported and consistent across all markers (separate 18S rRNA, 28S rRNA, and combined 18S rRNA+28S rRNA datasets) and methods (MP, ML) applied. Copyright © 2013 Elsevier Inc. All rights reserved.

Halechiniscidae (Heterotardigrada, Arthrotardigrada) of Oura Bay, Okinawajima, Ryukyu Islands, with descriptions of three new species

PubMed Central

Fujimoto, Shinta

2015-01-01

Abstract Marine tardigrades of the family Halechiniscidae (Heterotardigrada: Arthrotardigrada) are reported from Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan, including Dipodarctus sp., Florarctus wunai sp. n., Halechiniscus churakaagii sp. n., Halechiniscus yanakaagii sp. n. and Styraconyx sp. The attributes distinguishing Florarctus wunai sp. n. from its congeners is a combination of two characters, the smooth dorsal cuticle and two small projections of the caudal alae caestus. Halechiniscus churakaagii sp. n. is differentiated from its congeners by the combination of two characters, the robust cephalic cirrophores and the scapular processes with flat oval tips, while Halechiniscus yanakaagii sp. n. can be identified by the laterally protruded arched double processes with acute tips situated dorsally at the level of leg I. A list of marine tardigrades reported from the Ryukyu Islands is provided. PMID:25755627

Experimentally Induced Repeated Anhydrobiosis in the Eutardigrade Richtersius coronifer.

PubMed

Czernekova, Michaela; Jönsson, K Ingemar

2016-01-01

Tardigrades represent one of the main animal groups with anhydrobiotic capacity at any stage of their life cycle. The ability of tardigrades to survive repeated cycles of anhydrobiosis has rarely been studied but is of interest to understand the factors constraining anhydrobiotic survival. The main objective of this study was to investigate the patterns of survival of the eutardigrade Richtersius coronifer under repeated cycles of desiccation, and the potential effect of repeated desiccation on size, shape and number of storage cells. We also analyzed potential change in body size, gut content and frequency of mitotic storage cells. Specimens were kept under non-cultured conditions and desiccated under controlled relative humidity. After each desiccation cycle 10 specimens were selected for analysis of morphometric characteristics and mitosis. The study demonstrates that tardigrades may survive up to 6 repeated desiccations, with declining survival rates with increased number of desiccations. We found a significantly higher proportion of animals that were unable to contract properly into a tun stage during the desiccation process at the 5th and 6th desiccations. Also total number of storage cells declined at the 5th and 6th desiccations, while no effect on storage cell size was observed. The frequency of mitotic storage cells tended to decline with higher number of desiccation cycles. Our study shows that the number of consecutive cycles of anhydrobiosis that R. coronifer may undergo is limited, with increased inability for tun formation and energetic constraints as possible causal factors.

Molecular phylogeny of Arthrotardigrada (Tardigrada).

PubMed

Jørgensen, Aslak; Faurby, Søren; Hansen, Jesper G; Møbjerg, Nadja; Kristensen, Reinhardt M

2010-03-01

Tardigrades are microscopic ecdysozoans with a worldwide distribution covering marine, limnic and terrestrial habitats. They are regarded as a neglected phylum with regard to studies of their phylogeny. During the last decade molecular data have been included in the investigation of tardigrades. However, the marine arthrotardigrades are still poorly sampled due to their relative rarity, difficult identification and minute size even for tardigrades. In the present study, we have sampled various arthrotardigrades and sequenced the 18S and partial 28S ribosomal subunits. The phylogenetic analyses based on Bayesian inference and maximum parsimony inferred Heterotardigrada (Arthrotardigrada+Echiniscoidea) and Eutardigrada to be monophyletic. Arthrotardigrada was inferred to be paraphyletic as the monophyletic Echiniscoidea is included within the arthrotardigrades. The phylogenetic positions of Stygarctidae and Batillipedidae are poorly resolved with low branch support. The Halechiniscidae is inferred to be polyphyletic as the currently recognized Styraconyxinae is not part of the family. Archechiniscus is the sister-group to the Halechiniscidae and Orzeliscus is placed as one of the basal halechiniscids. The phylogeny of the included eutardigrade taxa resembles the current molecular phylogenies. The genetic diversity within Arthrotardigrada is much larger (18S 15.1-26.5%, 28S 7.2-20.7%) than within Eutardigrada (18S 1.0-12.6%, 28S 1.3-8.2%). This can be explained by higher substitution rates in the arthrotardigrades or by a much younger evolutionary age of the sampled eutardigrades. Copyright 2009 Elsevier Inc. All rights reserved.

Strong environmental tolerance of Artemia under very high pressure

NASA Astrophysics Data System (ADS)

Minami, K.; Ono, F.; Mori, Y.; Takarabe, K.; Saigusa, M.; Matsushima, Y.; Saini, N. L.; Yamashita, M.

2010-03-01

It was shown by the present authors group that a tardigrade in its tun-state can survive after exposed to 7.5 GPa for 13 hours. We have extended this experiment to other tiny animals searching for lives under extreme conditions of high hydrostatic pressure. Artemia, a kind of planktons, in its dried egg-state have strong environmental tolerance. Dozens of Artemia eggs were sealed in a small Teflon capsule together with a liquid pressure medium, and exposed to the high hydrostatic pressure of 7.5 GPa. After the pressure was released, they were soaked in seawater to observe hatching rate. It was proved that 80-90% of the Artemia eggs were alive and hatched into Nauplii after exposed to the maximum pressure of 7.5 GPa for up to 48 hours. Comparing with Tardigrades, Artemia are four-times stronger against high pressure.

Mechanisms of Resistance in Microbial Spores.

DTIC Science & Technology

1986-11-14

1702 by Leeuwenhoek with rotifers and nematodes. Cryptobiosis occurs also in the primitive tardigrade animals, the cysts and larvae of certain...excellent unicelTular, prokaryotic model for studying the extended maintenance of the organized structure that characterizes living organisms. Despite

Replicating the Conditions on Mars: the Possibility of Sustaining Life

NASA Astrophysics Data System (ADS)

Abdul-Masih, Michael; Guinan, E. F.

2013-01-01

We describe a laboratory experiment that replicates environmental conditions on Mars’s surface to determine the viability of Earth-based life under conditions on Mars. Of all the organisms currently known, the ones that are best suited for the harsh environments found throughout our solar system are the extremophiles found on Earth that tolerate extreme environmental conditions. The environmental conditions on Mars are the least extreme of all the planets in our solar system excluding Earth. The average temperature near the equator varies from +10 C to -20 C and the surface pressure is P ~ 0.01 Atm. The thin atmosphere means that the UV radiation from the Sun is relatively unshielded. Carbon Dioxide (CO2) makes up approximately 95% of Mars’ atmosphere and the soil is composed primarily of iron oxides. This being said, water can exist in liquid form under the surface and because of this, so can life. To test this, we constructed an air-tight chamber out of Plexiglas that replicates the environmental conditions on Mars. As a first step, two different organisms were tested for survival: E-coli, which was the control, and Hypsibius (Tardigrades), a member of the Tardigradas phylum. We hypothesized that the E-coli would perish while the more hardy Tardigrades would survive. The trials were two days each and the chosen temperature was ~4°C. Many trials were conducted. After the first compilation of the results, the hypothesis did not hold. The E-coli surprisingly survived while the Tardigrades did not survive. The E-coli did not grow while in the chamber, but after being removed they grew showing that they were still viable and that the conditions were not harsh enough to kill them. After these initial results, the experiment was altered slightly to ensure that the Tardigrades were able to successfully enter their hibernation like state that allows them to survive extreme conditions. These experiments are continuing and we will discuss the results under controlled

Experimentally Induced Repeated Anhydrobiosis in the Eutardigrade Richtersius coronifer

PubMed Central

2016-01-01

Tardigrades represent one of the main animal groups with anhydrobiotic capacity at any stage of their life cycle. The ability of tardigrades to survive repeated cycles of anhydrobiosis has rarely been studied but is of interest to understand the factors constraining anhydrobiotic survival. The main objective of this study was to investigate the patterns of survival of the eutardigrade Richtersius coronifer under repeated cycles of desiccation, and the potential effect of repeated desiccation on size, shape and number of storage cells. We also analyzed potential change in body size, gut content and frequency of mitotic storage cells. Specimens were kept under non-cultured conditions and desiccated under controlled relative humidity. After each desiccation cycle 10 specimens were selected for analysis of morphometric characteristics and mitosis. The study demonstrates that tardigrades may survive up to 6 repeated desiccations, with declining survival rates with increased number of desiccations. We found a significantly higher proportion of animals that were unable to contract properly into a tun stage during the desiccation process at the 5th and 6th desiccations. Also total number of storage cells declined at the 5th and 6th desiccations, while no effect on storage cell size was observed. The frequency of mitotic storage cells tended to decline with higher number of desiccation cycles. Our study shows that the number of consecutive cycles of anhydrobiosis that R. coronifer may undergo is limited, with increased inability for tun formation and energetic constraints as possible causal factors. PMID:27828978

Zoology: The Walking Heads.

PubMed

Maderspacher, Florian

2016-03-07

An analysis of Hox genes reveals that the body of the adorably weird tardigrades is essentially a truncated front end. This illustrates that loss and simplification are a hallmark of the evolution of animal body plans. Copyright © 2016 Elsevier Ltd. All rights reserved.

Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda.

PubMed

Smith, Frank W; Goldstein, Bob

2017-05-01

The origin and diversification of segmented metazoan body plans has fascinated biologists for over a century. The superphylum Panarthropoda includes three phyla of segmented animals-Euarthropoda, Onychophora, and Tardigrada. This superphylum includes representatives with relatively simple and representatives with relatively complex segmented body plans. At one extreme of this continuum, euarthropods exhibit an incredible diversity of serially homologous segments. Furthermore, distinct tagmosis patterns are exhibited by different classes of euarthropods. At the other extreme, all tardigrades share a simple segmented body plan that consists of a head and four leg-bearing segments. The modular body plans of panarthropods make them a tractable model for understanding diversification of animal body plans more generally. Here we review results of recent morphological and developmental studies of tardigrade segmentation. These results complement investigations of segmentation processes in other panarthropods and paleontological studies to illuminate the earliest steps in the evolution of panarthropod body plans. Copyright © 2016 Elsevier Ltd. All rights reserved.

EF-hand proteins and the regulation of actin-myosin interaction in the eutardigrade Hypsibius klebelsbergi (tardigrada).

PubMed

Prasath, Thiruketheeswaran; Greven, Hartmut; D'Haese, Jochen

2012-06-01

Many tardigrade species resist harsh environmental conditions by entering anhydrobiosis or cryobiosis. Desiccation as well as freeze resistance probably leads to changes of the ionic balance that includes the intracellular calcium concentration. In order to search for protein modifications affecting the calcium homoeostasis, we studied the regulatory system controlling actin-myosin interaction of the eutardigrade Hypsibius klebelsbergi and identified full-length cDNA clones for troponin C (TnC, 824 bp), calmodulin (CaM, 1,407 bp), essential myosin light chain (eMLC, 1,015 bp), and regulatory myosin light chain (rMLC, 984 bp) from a cDNA library. All four proteins belong to the EF-hand superfamily typified by a calcium coordinating helix-loop-helix motif. Further, we cloned and obtained recombinant TnC and both MLCs. CaM and TnC revealed four and two potential calcium-binding domains, respectively. Gel mobility shift assays demonstrated calcium-induced conformational transition of TnC. From both MLCs, only the rMLC showed one potential N-terminal EF-hand domain. Additionally, sequence properties suggest phosphorylation of this myosin light chain. Based on our results, we suggest a dual-regulated system at least in somatic muscles for tardigrades with a calcium-dependent tropomyosin-troponin complex bound to the actin filaments and a phosphorylation of the rMLC turning on and off both actin and myosin. Our results indicate no special modifications of the molecular structure and function of the EF-hand proteins in tardigrades. Phylogenetic trees of 131 TnCs, 96 rMLCs, and 62 eMLCs indicate affinities to Ecdysozoa, but also to some other taxa suggesting that our results reflect the complex evolution of these proteins rather than phylogenetic relationships. © 2012 WILEY PERIODICALS, INC.

DNA barcoding in Tardigrada: the first case study on Macrobiotus macrocalix Bertolani & Rebecchi 1993 (Eutardigrada, Macrobiotidae).

PubMed

Cesari, Michele; Bertolani, Roberto; Rebecchi, Lorena; Guidetti, Roberto

2009-05-01

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 closely related species confirm the possibility of identifying a specimen of this species by its cytochrome oxidase subunit I 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 Blackwell Publishing Ltd.

Annotated zoogeography of non-marine Tardigrada. Part I: Central America.

PubMed

Kaczmarek, Łukasz; Michalczyk, Łukasz; McInnes, Sandra J

2014-02-05

Dividing the world into nine regions, this first paper describes literature records of the limno-terrestrial tardigrades (Tardigrada) reported from Central America. Updating previously published species lists we have revised the taxonomy and provided additional habitat, geographic co-ordinates, and biogeographic comments. It is hoped this work will serve as a reference point and background for further zoogeographic studies.

A new Batillipedidae (Tardigrada, Arthrotardigrada) from Argentina.

PubMed

Menechella, Agustín G; Bulnes, Verónica N; Cazzaniga, Néstor J

2015-10-16

A new species of marine tardigrade, Batillipes acuticauda sp. n., has been found in midlittoral sand sediments collected at Monte Hermoso beach (Buenos Aires province, Argentina). The new species differs from all other members of Batillipedidae by its combination of caudal apparatus, lateral processes and toe patterns. It is the first description of an arthrotardigrade from Argentina.

Modulating Radiation Resistance: Novel Protection Paradigms Based on Defenses against Ionizing Radiation in the Extrempohile Deinococcus radiodurans

DTIC Science & Technology

2013-07-01

USA (2013); 2) Many environmental yeast are extremely radiation-resistant, accumulate nitrogenous Mn2+-Pi complexes, and highly resistant to...5 important in aerobic environments . Numerous organisms which accumulate “compatible solutes” fit this model, including representative archaea...cyanobacteria, lichens, alpine yeast, and tardigrades. 4.3 Knowns and Unknowns of Deinococcus Mn2+ Complexes It is worth reminding the reader

Tardigrada from a sub-Andean forest in the Sierra Nevada de Santa Marta (Colombia) with the description of Itaquascon pilatoi sp. nov.

PubMed

Lisi, Oscar; Londoño, Rosana; Quiroga, Sigmer

2014-07-29

Currently only 32 species of limno-terrestrial tardigrades have been reported in the literature for Colombia. Our study focused on both heterotardigrades and eutardigrades, which were extracted from eight samples of bryophytes and lichens collected in a sub-Andean forest transect in the Sierra Nevada de Santa Marta, Colombia. Fourteen species were found, six of which are new records for Colombia: Echiniscus madonnae Michalczyk & Kaczmarek, 2006, Echiniscus virginicus Riggin, 1962, Milnesium krzysztofi Kaczmarek & Michalczyk, 2007, Doryphoribius amazzonicus Lisi, 2011, Isohypsibius sattleri (Richters, 1902) and Diphascon higginsi Binda, 1971; and one new to science. Itaquascon pilatoi sp. nov., is characterized by having smooth cuticle, no eyes, buccal tube almost as long as the pharyngeal tube, well developed, obvious stylet furcae with long branches, slender claws, no lunules and no cuticular bars on the legs. The new species differs from I. umbellinae Barros, 1939, the most similar species, in having the stylet supports inserted precisely at the border between buccal and pharyngeal tube, more slender claws and more pronounced length differential between the external and internal claws of each leg. The total number of Colombian limno-terrestrial tardigrade species is raised to 37. 

Current Understanding of Ecdysozoa and its Internal Phylogenetic Relationships.

PubMed

Giribet, Gonzalo; Edgecombe, Gregory D

2017-09-01

Twenty years after its proposal, the monophyly of molting protostomes-Ecdysozoa-is a well-corroborated hypothesis, but the interrelationships of its major subclades are more ambiguous than is commonly appreciated. Morphological and molecular support for arthropods, onychophorans and tardigrades as a clade (Panarthropoda) continues to be challenged by a grouping of tardigrades with Nematoida in some molecular analyses, although onychophorans are consistently recovered as the sister group of arthropods. The status of Cycloneuralia and Scalidophora, each proposed by morphologists in the 1990s and widely employed in textbooks, is in flux: Cycloneuralia is typically non-monophyletic in molecular analyses, and Scalidophora is either contradicted or incompletely tested because of limited genomic and transcriptomic data for Loricifera, Kinorhyncha, and Priapulida. However, novel genomic data across Ecdysozoa should soon be available to tackle these difficult phylogenetic questions. The Cambrian fossil record indicates crown-group members of various ecdysozoan phyla as well as stem-group taxa that assist with reconstructing the most recent common ancestor of panarthropods and cycloneuralians. © The Author 2017. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Crystal structure of secretory abundant heat soluble protein 4 from one of the toughest “water bears” micro‐animals Ramazzottius Varieornatus

PubMed Central

Fukuda, Yohta

2018-01-01

Abstract Though anhydrobiotic tardigrades (micro‐animals also known as water bears) possess many genes of secretory abundant heat soluble (SAHS) proteins unique to Tardigrada, their functions are unknown. A previous crystallographic study revealed that a SAHS protein (RvSAHS1) from one of the toughest tardigrades, Ramazzottius varieornatus, has a β‐barrel architecture similar to fatty acid binding proteins (FABPs) and two putative ligand binding sites (LBS1 and LBS2) where fatty acids can bind. However, some SAHS proteins such as RvSAHS4 have different sets of amino acid residues at LBS1 and LBS2, implying that they prefer other ligands and have different functions. Here RvSAHS4 was crystallized and analyzed under a condition similar to that for RvSAHS1. There was no electron density corresponding to a fatty acid at LBS1 of RvSAHS4, where a putative fatty acid was observed in RvSAHS1. Instead, LBS2 of RvSAHS4, which was composed of uncharged residues, captured a putative polyethylene glycol molecule. These results suggest that RvSAHS4 mainly uses LBS2 for the binding of uncharged molecules. PMID:29493034

Death by Protein Damage in Irradiated Cells

DTIC Science & Technology

2011-01-01

tardigrades, J. Exp. Biol. 212 (2009) 4033– 4039. [63] A. Oren, N. Gunde-Cimerman, Mycosporines and mycosporine - like amino acids : UV protectants or...catalytically remove superoxide via a disproportionation mechanism [29,46]; and amino acids and peptides, which scav- enge hydroxyl radicals very efficiently...most radiation resistant mutants of B. pumilus displayed mul- tiple amino acid auxotrophies and a requirement for nicotinamide adenine dinucleotide

Annotated zoogeography of non-marine Tardigrada. Part II: South America.

PubMed

Kaczmarek, Łukasz; Michalczyk, Łukasz; Mcinnes, Sandra J

2015-02-25

This paper is the second monograph of nine that describes the global records of limno-terrestrial water bears (Tardigrada). Here, we provide a comprehensive list of non-marine tardigrades recorded from South America, providing an updated and revised taxonomy accompanied by geographic co-ordinates, habitat, and biogeographic comments. It is hoped this work will serve as a reference point and background for further zoogeographical and taxonomical studies.

Annotated zoogeography of non-marine Tardigrada. Part III: North America and Greenland.

PubMed

Kaczmarek, Łukasz; Michalczyk, Łukasz; McInnes, Sandra J

2016-12-01

This paper is the third monograph of the series that describes the global records of limno-terrestrial water bears (Tardigrada). Here, we provide a comprehensive list of non-marine tardigrades recorded from the North America, providing an updated and revised taxonomy accompanied by geographic co-ordinates, habitat, and biogeographic comments. It is hoped this work will serve as a reference point and background for further zoogeographical and taxonomical studies.

Strong environmental tolerance of moss Venturiella under very high pressure

NASA Astrophysics Data System (ADS)

Ono, F.; Mori, Y.; Takarabe, K.; Nishihira, N.; Shindo, A.; Saigusa, M.; Matsushima, Y.; Saini, N. L.; Yamashita, M.

2010-03-01

It was shown by the present authors group that tardigrade can survive under high pressure of 7.5 GPa. In the case of land plants, however, no result of such experiment has been reported. We have extended our experiments to moss searching for lives under very high pressure. Spore placentas of moss Venturiella were sealed in a small Teflon capsule together with a liquid pressure medium. The capsule was put in the center of a pyrophillite cube, and the maximum pressure of 7.5 GPa was applied using a two-stage cubic anvil press. The pressure was kept constant at the maximum pressure for12, 24, 72 and 144 hours. After the pressure was released, the spores were seeded on a ager medium, and incubated for one week and more longer at 25°C with white light of 2000 lux. It was proved that 70-90% of the spores were alive and germinated after exposed to the maximum pressure of 7.5 GPa for up to 72 hours. However, after exposed to 7.5 GPa for 6 days, only 4 individuals in a hundred were germinated. The pressure tolerance of moss Venturiella is found to be stronger than a small animal, tardigrade.

A transcriptome approach to ecdysozoan phylogeny.

PubMed

Borner, Janus; Rehm, Peter; Schill, Ralph O; Ebersberger, Ingo; Burmester, Thorsten

2014-11-01

The monophyly of Ecdysozoa, which comprise molting phyla, has received strong support from several lines of evidence. However, the internal relationships of Ecdysozoa are still contended. We generated expressed sequence tags from a priapulid (penis worm), a kinorhynch (mud dragon), a tardigrade (water bear) and five chelicerate taxa by 454 transcriptome sequencing. A multigene alignment was assembled from 63 taxa, which comprised after matrix optimization 24,249 amino acid positions with high data density (2.6% gaps, 19.1% missing data). Phylogenetic analyses employing various models support the monophyly of Ecdysozoa. A clade combining Priapulida and Kinorhyncha (i.e. Scalidophora) was recovered as the earliest branch among Ecdysozoa. We conclude that Cycloneuralia, a taxon erected to combine Priapulida, Kinorhyncha and Nematoda (and others), are paraphyletic. Rather Arthropoda (including Onychophora) are allied with Nematoda and Tardigrada. Within Arthropoda, we found strong support for most clades, including monophyletic Mandibulata and Pancrustacea. The phylogeny within the Euchelicerata remained largely unresolved. There is conflicting evidence on the position of tardigrades: While Bayesian and maximum likelihood analyses of only slowly evolving genes recovered Tardigrada as a sister group to Arthropoda, analyses of the full data set, and of subsets containing genes evolving at fast and intermediate rates identified a clade of Tardigrada and Nematoda. Notably, the latter topology is also supported by the analyses of indel patterns. Copyright © 2014 Elsevier Inc. All rights reserved.

A new species of the genus Hypsibius (Tardigrada: Parachela: Hypsibiidae) from Sakhalin island, far East Russia.

PubMed

Abe, Wataru

2004-09-01

A new species of semiterrestrial eutardigrade, Hypsibius stiliferus, is described from Sakhalin Island, Far East Russia. The new species is distinguished from its congeners by having an irregular, polygonal or subtriangular dorsal sculpture, which increases in size posteriorly, two granular macroplacoids, and a cuticular bar near the base of posterior claw 4, and by lacking a microplacoid and septulum. It is currently known from its type locality and several other localities in northern and southern Sakhalin Island. This is the first report concerning tardigrades from Sakhalin Island.

Assessing meiofaunal variation among individuals utilising morphological and molecular approaches: an example using the Tardigrada.

PubMed

Sands, Chester J; Convey, Peter; Linse, Katrin; McInnes, Sandra J

2008-04-30

Meiofauna - multicellular animals captured between sieve size 45 mum and 1000 mum - are a fundamental component of terrestrial, and marine benthic ecosystems, forming an integral element of food webs, and playing a critical roll in nutrient recycling. Most phyla have meiofaunal representatives and studies of these taxa impact on a wide variety of sub-disciplines as well as having social and economic implications. However, studies of variation in meiofauna are presented with several important challenges. Isolating individuals from a sample substrate is a time consuming process, and identification requires increasingly scarce taxonomic expertise. Finding suitable morphological characters in many of these organisms is often difficult even for experts. Molecular markers are extremely useful for identifying variation in morphologically conserved organisms. However, for many species markers need to be developed de novo, while DNA can often only be extracted from pooled samples in order to obtain sufficient quantity and quality. Importantly, multiple independent markers are required to reconcile gene evolution with species evolution. In this primarily methodological paper we provide a proof of principle of a novel and effective protocol for the isolation of meiofauna from an environmental sample. We also go on to illustrate examples of the implications arising from subsequent screening for genetic variation at the level of the individual using ribosomal, mitochondrial and single copy nuclear markers. To isolate individual tardigrades from their habitat substrate we used a non-toxic density gradient media that did not interfere with downstream biochemical processes. Using a simple DNA release technique and nested polymerase chain reaction with universal primers we were able amplify multi-copy and, to some extent, single copy genes from individual tardigrades. Maximum likelihood trees from ribosomal 18S, mitochondrial cytochrome oxidase subunit 1, and the single copy

First molecular data on the phylum Loricifera: an investigation into the phylogeny of ecdysozoa with emphasis on the positions of Loricifera and Priapulida.

PubMed

Park, Joong-Ki; Rho, Hyun Soo; Kristensen, Reinhardt Møbjerg; Kim, Won; Giribet, Gonzalo

2006-11-01

Recent progress in molecular techniques has generated a wealth of information for phylogenetic analysis. Among metazoans all but a single phylum have been incorporated into some sort of molecular analysis. However, the minute and rare species of the phylum Loricifera have remained elusive to molecular systematists. Here we report the first molecular sequence data (nearly complete 18S rRNA) for a member of the phylum Loricifera, Pliciloricus sp. from Korea. The new sequence data were analyzed together with 52 other ecdysozoan sequences, with all other phyla represented by three or more sequences. The data set was analyzed using parsimony as an optimality criterion under direct optimization as well as using a Bayesian approach. The parsimony analysis was also accompanied by a sensitivity analysis. The results of both analyses are largely congruent, finding monophyly of each ecdysozoan phylum, except for Priapulida, in which the coelomate Meiopriapulus is separate from a clade of pseudocoelomate priapulids. The data also suggest a relationship of the pseudocoelomate priapulids to kinorhynchs, and a relationship of nematodes to tardigrades. The Bayesian analysis placed the arthropods as the sister group to a clade that includes tardigrades and nematodes. However, these results were shown to be parameter dependent in the sensitivity analysis. The position of Loricifera was extremely unstable to parameter variation, and support for a relationship of loriciferans to any particular ecdysozoan phylum was not found in the data.

Milnesium berladnicorum sp. n. (Eutardigrada, Apochela, Milnesiidae), a new species of water bear from Romania.

PubMed

Ciobanu, Daniel Adrian; Zawierucha, Krzysztof; Moglan, Ioan; Kaczmarek, Lukasz

2014-01-01

In a lichen sample collected from a tree in Bârlad town (Vaslui County, Romania), a new tardigrade species belonging to the genus Milnesium (granulatum group) was found. Milnesium berladnicorum sp. n. is most similar (in the type of dorsal sculpture) to Milnesium beasleyi Kaczmarek et al., 2012 but differs from it mainly by having a different claw configuration and some morphometric characters. Additionally, the new species differs from other congeners of the granulatum group by the different type of dorsal sculpture, claw configuration and some morphometric characters.

Milnesium berladnicorum sp. n. (Eutardigrada, Apochela, Milnesiidae), a new species of water bear from Romania

PubMed Central

Ciobanu, Daniel Adrian; Zawierucha, Krzysztof; Moglan, Ioan; Kaczmarek, Łukasz

2014-01-01

Abstract In a lichen sample collected from a tree in Bârlad town (Vaslui County, Romania), a new tardigrade species belonging to the genus Milnesium (granulatum group) was found. Milnesium berladnicorum sp. n. is most similar (in the type of dorsal sculpture) to Milnesium beasleyi Kaczmarek et al., 2012 but differs from it mainly by having a different claw configuration and some morphometric characters. Additionally, the new species differs from other congeners of the granulatum group by the different type of dorsal sculpture, claw configuration and some morphometric characters. PMID:25147467

Determinants and taxonomic consequences of extreme egg shell variability in Ramazzottius subanomalus (Biserov, 1985) (Tardigrada).

PubMed

Stec, Daniel; Morek, Witold; Gąsiorek, Piotr; Kaczmarek, Łukasz; Michalczyk, Łukasz

2016-12-15

Nearly a half of known eutardigrade species lay ornamented eggs. The ornamentation is thought to provide attachment of the egg to the substrate and protection for the developing embryo, but from the taxonomic point of view chorion morphology may also provide key characters for species differentiation and identification, especially between closely related taxa. Nonetheless, despite the evolutionary and taxonomic importance of the egg shell, the determinants of its morphology are very poorly, if at all, understood. Here, we combine morphological, molecular and experimental approaches in an attempt to separate the genetic and environmental factors that shape egg chorion morphology in Ramazzottius subanomalus (Biserov, 1985). Our integrative study, based on a population of R. subanomalus isolated from a single moss sample, revealed (1) remarkable variation in egg shell morphology, but (2) relatively little variation in animal morphometric traits, and (3) genetic differentiation, expressed as two ITS-2 haplotypes, but no parallel polymorphism in COI. Although animals did not differ morphometrically between the haplotypes, eggs laid by haplotype 1 and 2 females exhibited highly statistically significant differences in all measured traits. The study demonstrates, for the first time, a correlation between phenotypic and genetic variability within a tardigrade species. The revealed congruence between genetic and morphological traits might be viewed as an example of incipient speciation that illustrates early evolutionary steps leading to species complexes that differ primarily in terms of egg shell morphology. Moreover, our data confirm the value of the ITS-2 fragment in distinguishing very closely related tardigrade lineages.

Assessing meiofaunal variation among individuals utilising morphological and molecular approaches: an example using the Tardigrada

PubMed Central

Sands, Chester J; Convey, Peter; Linse, Katrin; McInnes, Sandra J

2008-01-01

Background Meiofauna – multicellular animals captured between sieve size 45 μm and 1000 μm – are a fundamental component of terrestrial, and marine benthic ecosystems, forming an integral element of food webs, and playing a critical roll in nutrient recycling. Most phyla have meiofaunal representatives and studies of these taxa impact on a wide variety of sub-disciplines as well as having social and economic implications. However, studies of variation in meiofauna are presented with several important challenges. Isolating individuals from a sample substrate is a time consuming process, and identification requires increasingly scarce taxonomic expertise. Finding suitable morphological characters in many of these organisms is often difficult even for experts. Molecular markers are extremely useful for identifying variation in morphologically conserved organisms. However, for many species markers need to be developed de novo, while DNA can often only be extracted from pooled samples in order to obtain sufficient quantity and quality. Importantly, multiple independent markers are required to reconcile gene evolution with species evolution. In this primarily methodological paper we provide a proof of principle of a novel and effective protocol for the isolation of meiofauna from an environmental sample. We also go on to illustrate examples of the implications arising from subsequent screening for genetic variation at the level of the individual using ribosomal, mitochondrial and single copy nuclear markers. Results To isolate individual tardigrades from their habitat substrate we used a non-toxic density gradient media that did not interfere with downstream biochemical processes. Using a simple DNA release technique and nested polymerase chain reaction with universal primers we were able amplify multi-copy and, to some extent, single copy genes from individual tardigrades. Maximum likelihood trees from ribosomal 18S, mitochondrial cytochrome oxidase subunit 1, and

Evolution of pigment-dispersing factor neuropeptides in Panarthropoda: Insights from Onychophora (velvet worms) and Tardigrada (water bears).

PubMed

Mayer, Georg; Hering, Lars; Stosch, Juliane M; Stevenson, Paul A; Dircksen, Heinrich

2015-09-01

Pigment-dispersing factor (PDF) denotes a conserved family of homologous neuropeptides present in several invertebrate groups, including mollusks, nematodes, insects, and crustaceans (referred to here as pigment-dispersing hormone [PDH]). With regard to their encoding genes (pdf, pdh), insects possess only one, nematodes two, and decapod crustaceans up to three, but their phylogenetic relationship is unknown. To shed light on the origin and diversification of pdf/pdh homologs in Panarthropoda (Onychophora + Tardigrada + Arthropoda) and other molting animals (Ecdysozoa), we analyzed the transcriptomes of five distantly related onychophorans and a representative tardigrade and searched for putative pdf homologs in publically available genomes of other protostomes. This revealed only one pdf homolog in several mollusk and annelid species; two in Onychophora, Priapulida, and Nematoda; and three in Tardigrada. Phylogenetic analyses suggest that the last common ancestor of Panarthropoda possessed two pdf homologs, one of which was lost in the arthropod or arthropod/tardigrade lineage, followed by subsequent duplications of the remaining homolog in some taxa. Immunolocalization of PDF-like peptides in six onychophoran species, by using a broadly reactive antibody that recognizes PDF/PDH peptides in numerous species, revealed an elaborate system of neurons and fibers in their central and peripheral nervous systems. Large varicose projections in the heart suggest that the PDF neuropeptides functioned as both circulating hormones and locally released transmitters in the last common ancestor of Onychophora and Arthropoda. The lack of PDF-like-immunoreactive somata associated with the onychophoran optic ganglion conforms to the hypothesis that onychophoran eyes are homologous to the arthropod median ocelli. © 2015 Wiley Periodicals, Inc.

The Macrobiotus hufelandi group (Tardigrada) revisited.

PubMed

Kaczmarek, Łukasz; Michalczyk, Łukasz

2017-12-08

Species of the Macrobiotus hufelandi group are one of the most often recorded tardigrades throughout the globe. For over a century M. hufelandi has been considered cosmopolitan but in recent decades numerous species of similar morphologies have been described from various continents, which suggests that what was originally defined as a single taxon is, in fact, a complex of species. The definition of the hufelandi group is subject to a long-standing discussion and in this paper we propose a refined set of characters that are hoped to elucidate the taxonomic status of the group. In order to aid interspecific comparisons, we also propose a unified nomenclature for the crucial morphological traits and clar.

The evolution of the Ecdysozoa.

PubMed

Telford, Maximilian J; Bourlat, Sarah J; Economou, Andrew; Papillon, Daniel; Rota-Stabelli, Omar

2008-04-27

Ecdysozoa is a clade composed of eight phyla: the arthropods, tardigrades and onychophorans that share segmentation and appendages and the nematodes, nematomorphs, priapulids, kinorhynchs and loriciferans, which are worms with an anterior proboscis or introvert. Ecdysozoa contains the vast majority of animal species and there is a great diversity of body plans among both living and fossil members. The monophyly of the clade has been called into question by some workers based on analyses of whole genome datasets. We review the evidence that now conclusively supports the unique origin of these phyla. Relationships within Ecdysozoa are also controversial and we discuss the molecular and morphological evidence for a number of monophyletic groups within this superphylum.

Zur Biologie des marinen Heterotardigraden Tetrakentron synaptae

NASA Astrophysics Data System (ADS)

Kristensen, R. M.

1980-06-01

The life cycle of Tetrakentron synaptae Cuénot, 1892, a tardigrade closely associated with the sea cucumber Leptosynapta galliennei Herapath, was investigated in the littoral zone at Roscoff (France). Eggs and juveniles were found only in June and July, adults only from May to October. There are vagile males and stationary dwarf males. The dorsoventrally flattened body, an enlarged slimy epicuticle in females and dwarf males, the full set of claws also in juveniles, and the anus, which is in a dorsocaudal position, are indicative for an epizoic, sessile life. There is strong evidence that T. synaptae punctures the cells of L. galliennei and sucks out their content, which is indicative of parasitism.

Brain and eyes of Kerygmachela reveal protocerebral ancestry of the panarthropod head.

PubMed

Park, Tae-Yoon S; Kihm, Ji-Hoon; Woo, Jusun; Park, Changkun; Lee, Won Young; Smith, M Paul; Harper, David A T; Young, Fletcher; Nielsen, Arne T; Vinther, Jakob

2018-03-09

Recent discoveries of fossil nervous tissue in Cambrian fossils have allowed researchers to trace the origin and evolution of the complex arthropod head and brain based on stem groups close to the origin of the clade, rather than on extant, highly derived members. Here we show that Kerygmachela from Sirius Passet, North Greenland, a primitive stem-group euarthropod, exhibits a diminutive (protocerebral) brain that innervates both the eyes and frontal appendages. It has been surmised, based on developmental evidence, that the ancestor of vertebrates and arthropods had a tripartite brain, which is refuted by the fossil evidence presented here. Furthermore, based on the discovery of eyes in Kerygmachela, we suggest that the complex compound eyes in arthropods evolved from simple ocelli, present in onychophorans and tardigrades, rather than through the incorporation of a set of modified limbs.

Diversity and feeding strategies of soil microfauna along elevation gradients in Himalayan cold deserts

PubMed Central

Háněl, Ladislav; Řeháková, Klára; Doležal, Jiří

2017-01-01

High-elevation cold deserts in Tibet and Himalaya are one of the most extreme environments. One consequence is that the diversity of macrofauna in this environment is often limited, and soil microorganisms have a more influential role in governing key surface and subsurface bioprocesses. High-elevation soil microfauna represent important components of cold ecosystems and dominant consumers of microbial communities. Still little is known about their diversity and distribution on the edge of their reproductive and metabolic abilities. In this study, we disentangle the impact of elevation and soil chemistry on diversity and distribution of rotifers, nematodes and tardigrades and their most frequent feeding strategies (microbial filter-feeders, bacterivores, fungivores, root-fungal feeders, omnivores) along two contrasting altitudinal gradients in Indian NW Himalaya (Zanskar transect from 3805 to 4714 m a.s.l.) and southwestern Tibet (Tso Moriri transect from 4477 to 6176 m a.s.l.), using a combination of multivariate analysis, variation partitioning and generalized additive models. Zanskar transect had higher precipitation, soil moisture, organic matter and available nutrients than dry Tso Moriri transect. In total, 40 species of nematodes, 19 rotifers and 1 tardigrade were discovered. Species richness and total abundance of rotifers and nematodes showed mid-elevation peaks in both investigated transects. The optimum for rotifers was found at higher elevation than for nematodes. Diversity and distribution of soil microfauna was best explained by soil nitrogen, phosphorus and organic matter. More fertile soils hosted more diverse and abundant faunal communities. In Tso Moriri, bacterivores represented 60% of all nematodes, fungivores 35%, root-fungal feeders 1% and omnivores 3%. For Zanskar the respective proportions were 21%, 13%, 56% and 9%. Elevational optima of different feeding strategies occurred in Zanskar in one elevation zone (4400–4500 m), while in Tso

Direct and indirect effects of metal contamination on soil biota in a Zn-Pb post-mining and smelting area (S Poland).

PubMed

Kapusta, Paweł; Szarek-Łukaszewska, Grażyna; Stefanowicz, Anna M

2011-06-01

Effects of metal contamination on soil biota activity were investigated at 43 sites in 5 different habitats (defined by substratum and vegetation type) in a post-mining area. Sites were characterised in terms of soil pH and texture, nutrient status, total and exchangeable metal concentrations, as well as plant species richness and cover, abundances of enchytraeids, nematodes and tardigrades, and microbial respiration and biomass. The concentrations of total trace metals were highest in soils developed on mining waste (metal-rich dolomite), but these habitats were more attractive than sandy sites for plants and soil biota because of their higher content of organic matter, clay and nutrients. Soil mesofauna and microbes were strongly dependent on natural habitat properties. Pollution (exchangeable Zn and Cd) negatively affected only enchytraeid density; due to a positive relationship between enchytraeids and microbes it indirectly reduced microbial activity. Copyright © 2011 Elsevier Ltd. All rights reserved.

Dynamics of Lysozyme in Trehalose solutions

NASA Astrophysics Data System (ADS)

Ghatty, Pavan; Uberbacher, Edward C.

2008-03-01

Anhydrobiosis in Tardigrades and Nematodes has been a topic of constant interest and intrigue in the scientific community. An increase in the concentration of Trehalose has been attributed to the ability of some organisms to survive extreme conditions of temperature, pressure and pH. Although there exist many experimental studies attributing this effect to Trehalose, the molecular details governing the interaction between Trehalose and proteins remains unclear. We have conducted a 20ns study of Lysozyme in varying concentrations of Trehalose in water. Strong and weak hydrogen bonds and hydrophobic interactions between water, Trehalose and protein seem to dictate the interactions in the system. We have observed a hydrogen bonded network of Trehalose around the protein entrapping a layer of water between itself and protein. Lysozyme remains in a near-native conformation throughout the simulation giving hints on the ability of Trehalose in preserving the structure of protiens.

Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

NASA Astrophysics Data System (ADS)

Shibata, M.; Torigoe, M.; Matsumoto, Y.; Yamamoto, M.; Takizawa, N.; Hada, Y.; Mori, Y.; Takarabe, K.; Ono, F.

2014-05-01

Our studies on the tolerance of plants and animals against very high pressure of several GPa have been extended to a smaller sized fungus, the budding yeast Saccharomyces cerevisiae. Several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate, and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar. It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for longer than 12 h were found dead. The high pressure tolerance of budding yeast is a little weaker than that of tardigrades.

Center Innovation Fund: JSC CIF Characterize Human Forward Contamination

NASA Technical Reports Server (NTRS)

Rucker, Michelle A.

2017-01-01

Let's face it: wherever we go, we will inevitably carry along the little critters that live in and on us. Conventional wisdom has long held that it's unlikely those critters could survive the space environment, but in 2007 microscopic animals called Tardigrades survived exposure to space and in 2008 Cyanobacteria lived for 548 days outside the International Space Station (ISS). But what about the organisms we might reasonably expect a crewed spacecraft to leak or vent? Do we even know what they are? How long might our tiny hitch-hikers survive in close proximity to a warm spacecraft that periodically leaks/vents water or oxygen-and how might they mutate with long-duration exposure? Unlike the Mars rovers that we cleaned once and sent on their way, crew members will provide a constantly regenerating contaminant source. Are we prepared to certify that we can meet forward contamination protocols as we search for life at new destinations?

Ice Shelf Microbial Ecosystems in the High Arctic and Implications for Life on Snowball Earth

NASA Astrophysics Data System (ADS)

Vincent, W. F.; Gibson, J. A. E.; Pienitz, R.; Villeneuve, V.; Broady, P. A.; Hamilton, P. B.; Howard-Williams, C.

The Ward Hunt Ice Shelf (83°N, 74°W) is the largest remaining section of thick (>10m) landfast sea ice along the northern coastline of Ellesmere Island, Canada. Extensive meltwater lakes and streams occur on the surface of the ice and are colonized by photosynthetic microbial mat communities. This High Arctic cryo-ecosystem is similar in several of its physical, biological and geochemical features to the McMurdo Ice Shelf in Antarctica. The ice-mats in both polar regions are dominated by filamentous cyanobacteria but also contain diatoms, chlorophytes, flagellates, ciliates, nematodes, tardigrades and rotifers. The luxuriant Ward Hunt consortia also contain high concentrations (107-108cm-2) of viruses and heterotrophic bacteria. During periods of extensive ice cover, such as glaciations during the Proterozoic, cryotolerant mats of the type now found in these polar ice shelf ecosystems would have provided refugia for the survival, growth and evolution of a variety of organisms, including multicellular eukaryotes.

An extraterrestrial habitat on earth: The algal mat of Don Jaun Pond

NASA Astrophysics Data System (ADS)

Siegel, B. Z.; Siegel, S. M.; Chen, J.; Larock, P.

On the edge of Don Juan Pond in the Wright Valley of Antarctica lies a mat of mineral and detritus cemented by organic matter. In spite of a CaCl2 concentration of about 33% (w/v), the mat contains Oscillatoria and other cyanobacteria, unicellular forms, colonial forms rich in carotenoids, and diatoms. Bacteria are rare; fungal filaments are not. Oscillatoria showed motility, but only at temperatures <10°C. Acetone extracts of the mat and nearby muds yielded visible spectra similar to those of laboratory grown O. sancta, with 50- to 70-fold molar ratio of chlorophyll a to b. Although rare, tardigrades were also found. The algal mat had enzymatic activities characteristic of peroxidase, catalase, dehydrogenase, and amylase. Cellulose, chitin, protein, lipid and ATP were present. Previously, algae in the Wright Valley have been described in melt water, not in the brine itself. Wright Valley has been used as a near sterile Martian model. It obviously contains an array of hardy terrestrial organisms.

Effects of sewage sludge addition to Norway spruce seedlings on nitrogen availability and soil fauna in clear-cut areas.

PubMed

Nieminen, Jouni K; Räisänen, Mikko

2013-07-01

Anaerobically digested and composted sewage sludge (CSS) has been suggested to be a slow-release fertilizer in forestry and an alternative to quick-release inorganic fertilizers. The effects of CSS with or without added carbohydrate on inorganic nitrogen availability and on soil animals were tested in two Norway spruce plantations. Half of the seedlings were individually fertilized with CSS, and the rest were left as controls. Solid sucrose was added to half of the fertilized and untreated seedlings. Soil samples were taken in the autumn in the first and the second year after the treatments. CSS increased soil NH4-N (2100%), the proportion of soil NO3-N, and the N concentration of spruce needles. CSS greatly reduced the abundances of enchytraeids, tardigrades and collembolans, but increased the proportion and abundance of bacterial-feeding nematodes irrespective of carbohydrate addition. A better stabilization method needs to be developed before CSS can be used as a forest fertilizer. Copyright © 2013 Elsevier Ltd. All rights reserved.

An extraterrestrial habitat on Earth: the algal mat of Don Juan [correction of Jaun] Pond.

PubMed

Siegel, B Z; Siegel, S M; Chen, J; LaRock, P

1983-01-01

On the edge of Don Juan Pond in the Wright Valley of Antarctica lies a mat of mineral and detritus cemented by organic matter. In spite of a CaCl2 concentration of about 33% (w/v), the mat contains Oscillatoria and other cyanobacteria, unicellular forms, colonial forms rich in carotenoids, and diatoms. Bacteria are rare; fungal filaments are not. Oscillatoria showed motility but only at temperatures <10 degrees C. Acetone extracts of the mat and nearby muds yielded visible spectra similar to those of laboratory grown O. sancta, with 50- to 70-fold molar ratio of chlorophyll a to b. Although rare, tardigrades were also found. The algal mat had enzymatic activities characteristic of peroxidase, catalase, dehydrogenase, and amylase. Cellulose, chitin, protein, lipid and ATP were present. Previously, algae in the Wright Valley have been described in melt water, not in the brine itself. Wright Valley has been used as a near sterile Martian model. It obviously contains an array of hardy terrestrial organisms.

Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda

PubMed Central

Ou, Qiang; Shu, Degan; Mayer, Georg

2012-01-01

Cambrian lobopodians are important for understanding the evolution of arthropods, but despite their soft-bodied preservation, the organization of the cephalic region remains obscure. Here we describe new material of the early Cambrian lobopodian Onychodictyon ferox from southern China, which reveals hitherto unknown head structures. These include a proboscis with a terminal mouth, an anterior arcuate sclerite, a pair of ocellus-like eyes and branched, antenniform appendages associated with this ocular segment. These findings, combined with a comparison with other lobopodians, suggest that the head of the last common ancestor of fossil lobopodians and extant panarthropods comprized a single ocular segment with a proboscis and terminal mouth. The lack of specialized mouthparts in O. ferox and the involvement of non-homologous mouthparts in onychophorans, tardigrades and arthropods argue against a common origin of definitive mouth openings among panarthropods, whereas the embryonic stomodaeum might well be homologous at least in Onychophora and Arthropoda. PMID:23232391

Germ cell cluster organization and oogenesis in the tardigrade Dactylobiotus parthenogeneticus Bertolani, 1982 (Eutardigrada, Murrayidae).

PubMed

Poprawa, Izabela; Hyra, Marta; Rost-Roszkowska, Magdalena Maria

2015-07-01

Germ cell cluster organization and the process of oogenesis in Dactylobiotus parthenogeneticus have been described using transmission electron microscopy and light microscopy. The reproductive system of D. parthenogeneticus is composed of a single, sac-like, meroistic ovary and a single oviduct that opens into the cloaca. Two zones can be distinguished in the ovary: a small germarium that is filled with oogonia and a vitellarium that is filled with germ cell clusters. The germ cell cluster, which has the form of a modified rosette, consists of eight cells that are interconnected by stable cytoplasmic bridges. The cell that has the highest number of stable cytoplasmic bridges (four bridges) finally develops into the oocyte, while the remaining cells become trophocytes. Vitellogenesis of a mixed type occurs in D. parthenogeneticus. One part of the yolk material is produced inside the oocyte (autosynthesis), while the second part is synthesized in the trophocytes and transported to the oocyte through the cytoplasmic bridges. The eggs are covered with two envelopes: a thin vitelline envelope and a three-layered chorion. The surface of the chorion forms small conical processes, the shape of which is characteristic for the species that was examined. In our paper, we present the first report on the rosette type of germ cell clusters in Parachela.

Hallucigenia's head and the pharyngeal armature of early ecdysozoans.

PubMed

Smith, Martin R; Caron, Jean-Bernard

2015-07-02

The molecularly defined clade Ecdysozoa comprises the panarthropods (Euarthropoda, Onychophora and Tardigrada) and the cycloneuralian worms (Nematoda, Nematomorpha, Priapulida, Loricifera and Kinorhyncha). These disparate phyla are united by their means of moulting, but otherwise share few morphological characters--none of which has a meaningful fossilization potential. As such, the early evolutionary history of the group as a whole is largely uncharted. Here we redescribe the 508-million-year-old stem-group onychophoran Hallucigenia sparsa from the mid-Cambrian Burgess Shale. We document an elongate head with a pair of simple eyes, a terminal buccal chamber containing a radial array of sclerotized elements, and a differentiated foregut that is lined with acicular teeth. The radial elements and pharyngeal teeth resemble the sclerotized circumoral elements and pharyngeal teeth expressed in tardigrades, stem-group euarthropods and cycloneuralian worms. Phylogenetic results indicate that equivalent structures characterized the ancestral panarthropod and, seemingly, the ancestral ecdysozoan, demonstrating the deep homology of panarthropod and cycloneuralian mouthparts, and providing an anatomical synapomorphy for the ecdysozoan supergroup.

Three Echiniscidae species (Tardigrada: Heterotardigrada) new to the Polish fauna, with the description of a new gonochoristic Bryodelphax Thulin, 1928.

PubMed

GĄsiorek, Piotr; Degma, Peter

2018-04-16

During a faunistic survey in the Pieniny and Tatra Mountains three species of Echiniscidae new to Poland, including one new to science, were found. Bryodelphax instabilis sp. nov. is characterised by an instable number of ventral plates, deep faceting of the scapular plate, having dorsal plates covered either with pseudopores or pores, and striking sexual dimorphism. Two first records, namely Echiniscus militaris and E. spiniger, are rare taxa of upland-mountain character, which have already been reported from a few European countries since the original description at the beginning of the XXth century. The interspecific appendage length variability and development of pedal plates in the spinulosus group, to which E. spiniger belongs, and their taxonomic importance is discussed. Notes relating to sexual dimorphism within the newly recorded Pseudechiniscus facettalis, are also presented. Echiniscus testudo is reported from the Polish part of the Tatra Mountains for the first time. Succeeding findings confirm the high tardigrade α-diversity in the Polish mountain ranges. An amended key for Polish Heterotardigrada is provided.

Fluctuations in the meiofauna of the Aufwuchs community in a brackish-water lagoon

NASA Astrophysics Data System (ADS)

Little, Colin

1986-08-01

The organization of the Aufwuchs community in a brackish-water lagoon (Swanpool, Falmouth, U.K.) is described. Changes in the population densities of encrusting bryozoans and mobile meiofauna are described for a period of 3 years. Most meiofaunal species reached peak densities in the spring (January-March). These included tardigrades ( Macrobiotus sp.), oligochaetes ( Nais elinguis, Chaetogaster diaphanus), the harpacticoid copepod Schizopera clandestina, ostracods, the nematodes Dichromadora geophila and Theristus spp., and possibly the nematodes Chromadorina germanica and Atrochromadora microlaima. Other meiofaunal populations peaked in summer (July-September), and these included the chironomid Chironomus salinarius, the harpacticoid copepod Nitocra spinipes and the nematode Adoncholaimus thalassophygas. Two further species, the mite Halacarus balticus and the nematode Aphelencoides sp., showed irregular bursts in numbers. It is concluded that the spring-peaking species increased in numbers dependent upon the growth of the Aufwuchs, and particularly of the surface film of diatoms, while the summer-peaking species may have been controlled more by limiting values of salinity and temperature. These conclusions are contrasted with the general view of salinity as the over-riding factor in brackish-water ecosystems.

A description of Macrobiotus horningi sp. nov. and redescriptions of M. maculatus comb. nov. Iharos, 1973 and M. rawsoni Horning et al., 1978 (Tardigrada: Eutardigrada: Macrobiotidae: hufelandi group).

PubMed

Kaczmarek, Łukasz; Michalczyk, Łukasz

2017-12-08

We examined microscope slides from Horning and Iharos tardigrade collections from Museum of New Zealand Te Papa Tongarewa in Wellington and Hungarian Natural History Museum in Budapest with species of the Macrobiotus hufelandi group. Based on this material we describe one new species, Macrobiotus horningi sp. nov., and re-describe two others, M. maculatus comb. nov. Iharos, 1973 and M. rawsoni Horning et al., 1978. With the oral cavity armature of the patagonicus type and chorion of the hufelandi type, Macrobiotus horningi sp. nov. is most similar to: M. personatus Biserov, 1990, M. sandrae Bertolani & Rebecchi, 1993, M. serratus Bertolani et al., 1996, M. sottilei Pilato et al., 2012, M. terminalis Bertolani & Rebecchi, 1993 and M. vladimiri Bertolani et al., 2011, but it differs from them in morphological and morphometric traits. With eggs of the maculatus type, M. maculatus comb. nov. is most similar to: M. biserovi Bertolani et al., 1996, M. denticulatus Dastych, 2002, M. macrocalix Bertolani & Rebecchi, 1993 and M. ramoli Dastych, 2005, but differs from them in morphological and morphometric characters.

The limnology and biology of the Dufek Massif, Transantarctic Mountains 82° South

NASA Astrophysics Data System (ADS)

Hodgson, Dominic A.; Convey, Peter; Verleyen, Elie; Vyverman, Wim; McInnes, Sandra J.; Sands, Chester J.; Fernández-Carazo, Rafael; Wilmotte, Annick; De Wever, Aaike; Peeters, Karolien; Tavernier, Ines; Willems, Anne

2010-08-01

Very little is known about the higher latitude inland biology of continental Antarctica. In this paper we describe the limnology and biology of the Dufek Massif, using a range of observational, microscopic and molecular methods. Here two dry valleys are home to some of the southernmost biota on Earth. Cyanobacteria were the dominant life forms, being found in lakes and ponds, in hypersaline brines, summer melt water, relict pond beds and in exposed terrestrial habitats. Their species diversity was the lowest yet observed in Antarctic lakes. Green algae, cercozoa and bacteria were present, but diatoms were absent except for a single valve; likely windblown. Mosses were absent and only one lichen specimen was found. The Metazoa included three microbivorous tardigrades ( Acutuncus antarcticus, Diphascon sanae and Echiniscus (cf) pseudowendti) and bdelloid rotifer species, but no arthropods or nematodes. These simple faunal and floral communities are missing most of the elements normally present at lower latitudes in the Antarctic which is probably a result of the very harsh environmental conditions in the area.

Ultrastructural changes of the midgut epithelium in Isohypsibius granulifer granulifer Thulin, 1928 (Tardigrada: Eutardigrada) during oogenesis.

PubMed

Rost-Roszkowska, Magdalena M; Poprawa, Izabela; Wójtowicz, Maria; Kaczmarek, Lukasz

2011-04-01

The midgut epithelium of Isohypsibius granulifer granulifer (Eutardigrada) is composed of columnar digestive cells. At its anterior end, a group of cells with cytoplasm which differs from the cytoplasm of digestive cells is present. Probably, those cells respond to crescent-like cells (midgut regenerative cells) described for some tardigrade species. Their mitotic divisions have not been observed. We analyzed the ultrastructure of midgut digestive cells in relation to five different stages of oogenesis (previtellogenesis, beginning of the vitellogenesis, vitellogenesis--early choriogenesis, vitellogenesis--middle choriogenesis, late choriogenesis). In the midgut epithelium cells, the gradual accumulation of glycogen granules, lipid droplets and structures of varying electron density occurs. During vitellogenesis and choriogenesis, in the cytoplasm of midgut cells we observed the increasing number of organelles which are responsible for the intensive synthesis of lipids, proteins and saccharides such as cisterns of endoplasmic reticulum and Golgi complexes. At the end of oogenesis, autophagy also intensifies in midgut epithelial cells, which is probably caused by the great amount of reserve material. Midgut epithelium of analyzed species takes part in the yolk precursor synthesis.

A new tardigrade, Mutaparadoxipus duodigifinis gen. nov., sp. nov. (Heterotardigrada: Arthrotardigrada), from the Southeastern United States.

PubMed

Gross, Vladimir; Miller, William R; Hochberg, Rick

2014-07-10

A new genus and species of Arthrotardigrada is described from Florida, USA based on its unique adhesive pad/claw combinations. Mutaparadoxipus duodigifinis gen. nov., sp. nov., is characterized by well-developed, ventral secondary clavae that are adjacent to the mouth, pointed lateral and caudal alae, seminal receptacles with coiled ducts opening lateral to the gonopore, and all legs with digits bearing proximal adhesive pads. Distal claws are present on digits I-III of legs I-III, but are missing from digit IV. On leg IV, distal claws are present only on digits II & III. A single accessory point is present on claws II & III only. This is the fourth species discovered to date with proximal adhesive pads, increasing support for a clade of adhesive-padded arthrotardigrades, and is likely the sister taxon of Paradoxipus orzeliscoides. The incomplete set of claws may represent an evolutionary step in a progressive loss of claws hypothesized to have occurred within the Halechiniscidae. The subfamily Orzeliscinae is amended as a result.

Tolerance to Ammonia of Thulinius ruffoi (Bertolani, 1981), a Tardigrade Isolated from a Sewage Treatment Plant.

PubMed

Sobczyk, Mateusz; Michno, Klaudia; Kosztyła, Paulina; Stec, Daniel; Michalczyk, Łukasz

2015-12-01

The acute toxicity of ammonia on Thulinius ruffoi (Bertolani, 1981), a eutardigrade isolated from a small waste water treatment plant (WWTP) in Poland, was estimated. Our results show that no active individuals survived a 24 h exposure to solutions equal to or higher than 125 mg/L of total ammonia nitrogen (NH3-N + NH4 (+)-N), which, under the conditions in our experiment, was equivalent to 1.17 mg/L of un-ionised ammonia (NH3). The LC50 concentration of total ammonia nitrogen was equal to 52 mg/L (or 0.65 mg/L un-ionised ammonia). Given that the norms for the concentration of ammonia in treated waters leaving WWTPs are usually several times lower than the LC50 for T. ruffoi, this species does not seem to be a good bioindicator candidate for WWTPs. In this paper we also note that various ecotoxicological studies use different methodological approaches and we suggest that a more uniform methodology may aid interspecific comparisons of LC50 values.

Tolerance of budding yeast Saccharomyces cerevisiae to ultra high pressure

NASA Astrophysics Data System (ADS)

Ono, Fumihisa; Shibata, Michiko; Torigoe, Motoki; Matsumoto, Yuta; Yamamoto, Shinsuke; Takizawa, Noboru; Hada, Yoshio; Mori, Yoshihisa; Takarabe, Kenichi

2013-06-01

In our previous studies on the tolerance of small plants and animals to the high hydrostatic pressure of 7.5 GPa, it was shown that all the living samples could be borne at this high pressure, which is more than one order of magnitude higher than the proteinic denaturation pressure. To make this inconsistency clear, we have extended these studies to a smaller sized fungus, budding yeast Saccharomyces cerevisiae. A several pieces of budding yeast (dry yeast) were sealed in a small teflon capsule with a liquid pressure medium fluorinate (PC72, Sumitomo 3M), and exposed to 7.5 GPa by using a cubic anvil press. The pressure was kept constant for various duration of time from 2 to 24 h. After the pressure was released, the specimens were brought out from the teflon capsule, and they were cultivated on a potato dextrose agar (PDA). It was found that the budding yeast exposed to 7.5 GPa for up to 6 h showed multiplication. However, those exposed to 7.5 GPa for 12 and 24 h were found dead. The high pressure tolerance of budding yeast is weaker than that of tardigrades.

Integrative taxonomy allows the identification of synonymous species and the erection of a new genus of Echiniscidae (Tardigrada, Heterotardigrada).

PubMed

Vicente, Filipe; Fontoura, Paulo; Cesari, Michele; Rebecchi, Lorena; Guidetti, Roberto; Serrano, Artur; Bertolani, Roberto

2013-02-14

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. Addition-ally, 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.

Unlocking the early fossil record of the arthropod central nervous system

PubMed Central

Edgecombe, Gregory D.; Ma, Xiaoya; Strausfeld, Nicholas J.

2015-01-01

Extant panarthropods (euarthropods, onychophorans and tardigrades) are hallmarked by stunning morphological and taxonomic diversity, but their central nervous systems (CNS) are relatively conserved. The timing of divergences of the ground pattern CNS organization of the major panarthropod clades has been poorly constrained because of a scarcity of data from their early fossil record. Although the CNS has been documented in three-dimensional detail in insects from Cenozoic ambers, it is widely assumed that these tissues are too prone to decay to withstand other styles of fossilization or geologically older preservation. However, Cambrian Burgess Shale-type compressions have emerged as sources of fossilized brains and nerve cords. CNS in these Cambrian fossils are preserved as carbon films or as iron oxides/hydroxides after pyrite in association with carbon. Experiments with carcasses compacted in fine-grained sediment depict preservation of neural tissue for a more prolonged temporal window than anticipated by decay experiments in other media. CNS and compound eye characters in exceptionally preserved Cambrian fossils predict divergences of the mandibulate and chelicerate ground patterns by Cambrian Stage 3 (ca 518 Ma), a dating that is compatible with molecular estimates for these splits. PMID:26554038

The extent of wind-mediated dispersal of small metazoans, focusing nematodes.

PubMed

Ptatscheck, Christoph; Gansfort, Birgit; Traunspurger, Walter

2018-05-01

Wind-mediated transport is an important mechanism in the dispersal of small metazoans. Yet, concrete dispersal rates have hardly been examined. Here we present the results of an one-year field experiment investigating the composition and dispersal rates of aeroplankton. To gain insights into the dynamics of dispersal at the species level, we focused on nematodes, worldwide the most common metazoan taxon. Among the six taxa collected in this study (nematodes, rotifers, collembolans, tardigrades, mites, and thrips), nematodes had the highest dispersal rates (up to >3000 individuals m -2 in 4 weeks, 27 species identified) and represented >44% of aeroplankton. Only living nematodes, and no propagules, were dispersed. All taxa had a higher dispersal potential in environments linked to the source habitat, evidenced by the much higher deposition of organisms in funnels placed on the ground than on the rooftop of a ten-story building. Nematodes under conditions of high humidity and wind speed had the highest dispersal rates, while increasing temperatures and dryness had a significantly positive impact on the wind drift of mites and thrips. The results indicated that wind dispersal over long distances is possible. The notable organismal input by wind dispersal may contribute to biodiversity and ecosystem functions.

What shapes edaphic communities in mineral and ornithogenic soils of Cierva Point, Antarctic Peninsula?

NASA Astrophysics Data System (ADS)

Mataloni, G.; Garraza, G. González; Bölter, M.; Convey, P.; Fermani, P.

2010-08-01

Three mineral soil and four ornithogenic soil sites were sampled during summer 2006 at Cierva Point (Antarctic Peninsula) to study their bacterial, microalgal and faunal communities in relation to abiotic and biotic features. Soil moisture, pH, conductivity, organic matter and nutrient contents were consistently lower and more homogeneous in mineral soils. Ornithogenic soils supported larger and more variable bacterial abundances than mineral ones. Algal communities from mineral soils were more diverse than those from ornithogenic soils, although chlorophyll- a concentrations were significantly higher in the latter. This parameter and bacterial abundance were correlated with nutrient and organic matter contents. The meiofauna obtained from mineral soils was homogeneous, with one nematode species dominating all samples. The fauna of ornithogenic soils varied widely in composition and abundance. Tardigrades and rotifers dominated the meiofauna at eutrophic O2, where they supported a large population of the predatory nematode Coomansus gerlachei. At site O3, high bacterial abundance was consistent with high densities of the bacterivorous nematodes Plectus spp. This study provides evidence that Antarctic soils are complex and diverse systems, and suggests that biotic interactions (e.g. competition and predation) may have a stronger and more direct influence on community variability in space and time than previously thought.

Organization and mobility of water in amorphous and crystalline trehalose

NASA Astrophysics Data System (ADS)

Kilburn, Duncan; Townrow, Sam; Meunier, Vincent; Richardson, Robert; Alam, Ashraf; Ubbink, Job

2006-08-01

The disaccharide trehalose is accumulated by microorganisms, such as yeasts, and multicellular organisms, such as tardigrades, when conditions of extreme drought occur. In this way these organisms can withstand dehydration through the formation of an intracellular carbohydrate glass, which, with its high viscosity and hydrogen-bonding interactions, stabilizes and protects the integrity of complex biological structures and molecules. This property of trehalose can also be harnessed in the stabilization of liposomes, proteins and in the preservation of red blood cells, but the underlying mechanism of bioprotection is not yet fully understood. Here we use positron annihilation lifetime spectroscopy to probe the free volume of trehalose matrices; specifically, we develop a molecular picture of the organization and mobility of water in both amorphous and crystalline states. Whereas in amorphous matrices, water increases the average intermolecular hole size, in the crystalline dihydrate it is organized as a confined one-dimensional fluid in channels of fixed diameter that allow activated diffusion of water in and out of the crystallites. We present direct real-time evidence of water molecules unloading reversibly from these channels, thereby acting as both a sink and a source of water in low-moisture systems. We postulate that this behaviour may provide the overall stability required to keep organisms viable through dehydration conditions.

Meiofauna communities along an abyssal depth gradient in the Drake Passage

NASA Astrophysics Data System (ADS)

Gutzmann, E.; Martínez Arbizu, P.; Rose, A.; Veit-Köhler, G.

2004-07-01

Meiofauna standing stocks and community structure are reported for the first time for abyssal soft-sediment samples in Antarctic waters. At seven stations within a depth range of 2274-5194 m a total of 128 sediment cores were retrieved with a multiple corer (MUC) on board of the R.V. Polarstern during the ANDEEP-1 cruise (ANT XIX/3). The metazoan meiofauna (defined by a lower size limit of 40 μm) was identified and counted, and one core per station was preserved for CPE, C/N, TOM and grain size analyses. Meiofauna densities are in the range of 2731 Ind./10 cm 2 at 2290 m depth and 75 Ind./10 cm 2 at 3597 m depth, with nematodes being the dominant group at all stations. Nematodes account for 84-94% followed by copepods with 2-8% of the total meiofauna. Other frequent taxa found at each station are kinorhynchs, loriciferans, tantulocarids, ostracods and tardigrades. There is a general tendency of decreasing abundances of metazoan meiofauna with increasing depth, but not all higher level taxa displayed this pattern. In addition, a tendency of decreasing higher taxon density with increasing depth was observed. Standing stocks are higher than the average found at similar depths in other oceans.

Panspermia Survival Scenarios for Organisms that Survive Typical Hypervelocity Solar System Impact Events.

NASA Astrophysics Data System (ADS)

Pasini, D.

2014-04-01

Previous experimental studies have demonstrated the survivability of living cells during hypervelocity impact events, testing the panspermia and litho-panspermia hypotheses [1]. It has been demonstrated by the authors that Nannochloropsis Oculata Phytoplankton, a eukaryotic photosynthesizing autotroph found in the 'euphotic zone' (sunlit surface layers of oceans [2]), survive impacts up to 6.93 km s-1 (approx. shock pressure 40 GPa) [3, 4]. Also shown to survive impacts up to 5.49 km s-1 is the tardigrade species Hypsibius dujardini (a complex micro-animal consisting of 40,000 cells) [5, 6]. It has also been shown that they can survive sustained pressures up to 600 MPa using a water filled pressure capsule [7]. Additionally bacteria can survive impacts up to 5.4 km s-1 (~30 GPa) - albeit with a low probability of survival [1], and the survivability of yeast spores in impacts up to 7.4 km s-1 (~30 GPa) has also recently been demonstrated [8]. Other groups have also reported that the lichen Xanthoria elegans is able to survive shocks in similar pressure ranges (~40 GPa) [9]. Here we present various simulated impact regimes to show which scenarios are condusive to the panspermia hypothesis of the natural transfer of life (via an icy body) through space to an extraterrestrial environment.

New records of marine tardigrades from Moorea, French Polynesia, with the description of Styraconyx turbinarium sp. nov. (Arthrotardigrada, Halechiniscidae).

PubMed

Bartels, Paul J; Fontoura, Paulo; Nelson, Diane R

2015-05-05

Five marine arthrotardigrade species are recorded from Moorea, Society Islands, French Polynesia. Four were collected from coral sand; two, Dipodarctus anaholiensis Pollock, 1995 and Florarctus kwoni Chang & Rho, 1997, are new records for the region, and two, Halechiniscus perfectus Schulz, 1955 and Styraconyx kristenseni kristenseni Renaud-Mornant, 1981, have been previously reported. The fifth, a new species Styraconyx turbinarium sp. nov., is described and was collected from the drifting brown alga Turbinaria ornata. The new species is characterized by the presence of peduncles on all digits, an elongate primary clava, and the lateral cirrus A arising from a common pedestal and enveloped by a common membrane extending almost to the claval tip. The new species differs from the most similar species, Styraconyx tyrrhenus D'Addabbo Gallo, Morone De Lucia & de Zio Grimaldi, 1989, by having longer and differently shaped primary clavae which are elongated in the new species and club-shaped in S. tyrrhenus. By having a dorsal cuticle that is coarsely punctated but without folds or other ornamentations, the new species can be easily distinguished from S. craticulus (Pollock, 1983), a species with similar primary clavae, but with cuticular dorsal folds ornamented with a grid-like pattern.

MicroRNAs and phylogenomics resolve the relationships of Tardigrada and suggest that velvet worms are the sister group of Arthropoda.

PubMed

Campbell, Lahcen I; Rota-Stabelli, Omar; Edgecombe, Gregory D; Marchioro, Trevor; Longhorn, Stuart J; Telford, Maximilian J; Philippe, Hervé; Rebecchi, Lorena; Peterson, Kevin J; Pisani, Davide

2011-09-20

Morphological data traditionally group Tardigrada (water bears), Onychophora (velvet worms), and Arthropoda (e.g., spiders, insects, and their allies) into a monophyletic group of invertebrates with walking appendages known as the Panarthropoda. However, molecular data generally do not support the inclusion of tardigrades within the Panarthropoda, but instead place them closer to Nematoda (roundworms). Here we present results from the analyses of two independent genomic datasets, expressed sequence tags (ESTs) and microRNAs (miRNAs), which congruently resolve the phylogenetic relationships of Tardigrada. Our EST analyses, based on 49,023 amino acid sites from 255 proteins, significantly support a monophyletic Panarthropoda including Tardigrada and suggest a sister group relationship between Arthropoda and Onychophora. Using careful experimental manipulations--comparisons of model fit, signal dissection, and taxonomic pruning--we show that support for a Tardigrada + Nematoda group derives from the phylogenetic artifact of long-branch attraction. Our small RNA libraries fully support our EST results; no miRNAs were found to link Tardigrada and Nematoda, whereas all panarthropods were found to share one unique miRNA (miR-276). In addition, Onychophora and Arthropoda were found to share a second miRNA (miR-305). Our study confirms the monophyly of the legged ecdysozoans, shows that past support for a Tardigrada + Nematoda group was due to long-branch attraction, and suggests that the velvet worms are the sister group to the arthropods.

Three new Batillipes species (Arthrotardigrada: Batillipedidae) from the Brazilian coast.

PubMed

Santos, Erika; Rocha, Clélia M C DA; Gomes, Edivaldo Jr; Fontoura, Paulo

2017-03-16

Three new tardigrade species, Batillipes brasiliensis sp. nov., Batillipes dandarae sp. nov. and Batillipes potiguarensis sp. nov., are described from shallow subtidal sediments of the Brazilian coast. B. brasiliensis sp. nov. and B. dandarae sp. nov. have toes 3 and 4 on leg IV different in length, so they can be included in the D group of species, while B. potiguarensis sp. nov., with toes 3 and 4 on leg IV equal in length belong to the A group. Batillipes brasiliensis sp. nov. is characterized by having an ala-like caudal expansion; cuticular projections on the coxal region of legs I-III, and lateral projections. The lateral projection located between the third and fourth legs is fringed with digit-shaped expansions. Batillipes dandarae sp. nov. has a dorsal blunt enlargement in the scapular region; a pointed triangular caudal appendage, and no lateral projections. The new species exhibits a sensorial spine on legs I inserted posteriorly and turning forward, and anus surrounded by a peculiar cuticular structure constituted by six platelets. Batillipes potiguarensis sp. nov. is characterized by a unique combination of characters: scapular region well developed, protruding laterally at the level of the first pair of legs; lateral blunt processes between legs, and prominent roundish caudal protrusion. In addition, the new species exhibits cephalic appendages with swollen tips, evident secondary clavae, and very short sense organs on the legs IV.

Bioinformatic prediction of arthropod/nematode-like peptides in non-arthropod, non-nematode members of the Ecdysozoa.

PubMed

Christie, Andrew E; Nolan, Daniel H; Garcia, Zachery A; McCoole, Matthew D; Harmon, Sarah M; Congdon-Jones, Benjamin; Ohno, Paul; Hartline, Niko; Congdon, Clare Bates; Baer, Kevin N; Lenz, Petra H

2011-02-01

The Onychophora, Priapulida and Tardigrada, along with the Arthropoda, Nematoda and several other small phyla, form the superphylum Ecdysozoa. Numerous peptidomic studies have been undertaken for both the arthropods and nematodes, resulting in the identification of many peptides from each group. In contrast, little is known about the peptides used as paracrines/hormones by species from the other ecdysozoan taxa. Here, transcriptome mining and bioinformatic peptide prediction were used to identify peptides in members of the Onychophora, Priapulida and Tardigrada, the only non-arthropod, non-nematode members of the Ecdysozoa for which there are publicly accessible expressed sequence tags (ESTs). The extant ESTs for each phylum were queried using 106 arthropod/nematode peptide precursors. Transcripts encoding calcitonin-like diuretic hormone and pigment-dispersing hormone (PDH) were identified for the onychophoran Peripatopsis sedgwicki, with transcripts encoding C-type allatostatin (C-AST) and FMRFamide-like peptide identified for the priapulid Priapulus caudatus. For the Tardigrada, transcripts encoding members of the A-type allatostatin, C-AST, insect kinin, orcokinin, PDH and tachykinin-related peptide families were identified, all but one from Hypsibius dujardini (the exception being a Milnesium tardigradum orcokinin-encoding transcript). The proteins deduced from these ESTs resulted in the prediction of 48 novel peptides, six onychophoran, eight priapulid and 34 tardigrade, which are the first described from these phyla. Copyright © 2010 Elsevier Inc. All rights reserved.

Tardigrades of the Tree Canopy: Milnesium swansoni sp. nov. (Eutardigrada: Apochela: Milnesiidae) a new species from Kansas, U.S.A.

PubMed

Young, Alexander; Chappell, Benjamin; Miller, William; Lowman, Margaret

2016-02-04

Milnesium swansoni sp. nov. is a new species of Eutardigrada described from the tree canopy in eastern Kansas, USA. This species within the order Apochela, family Milnesiidae, genus Milnesium is distinguished by its smooth cuticle, narrow buccal tube, four peribuccal lamellae, primary claws without accessory points, and a secondary claw configuration of [3-3]-[3-3]. The buccal tube appears to be only half the width of the nominal species Milnesium tardigradum for animals of similar body length. The species adds to the available data for the phylum, and raises questions concerning species distribution.

Ovary organization and oogenesis in the tardigrade Macrobiotus polonicus Pilato, Kaczmarek, Michalczyk & Lisi, 2003 (Eutardigrada, Macrobiotidae): ultrastructural and histochemical analysis.

PubMed

Poprawa, Izabela; Schlechte-Wełnicz, Weronika; Hyra, Marta

2015-05-01

The female reproductive system, the process of oogenesis, and the morphology of the egg capsule of Macrobiotus polonicus were analyzed using transmission and scanning electron microscopy and histochemical methods. The female reproductive system of Macrobiotus polonicus consists of a single ovary and a single oviduct that opens into the cloaca. The seminal receptacle filled with sperm cells is present. The ovary is divided into two parts: a germarium that is filled with oogonia and a vitellarium that is filled with branched clusters of the germ cells. Meroistic oogenesis occurs in the species that was examined. The yolk material is synthesized by the oocyte (autosynthesis) and by the trophocytes and is transported to the oocyte through cytoplasmic bridges. The process of the formation of the egg envelopes starts in the late vitellogenesis. The egg capsule is composed of two envelopes-the vitelline envelope and the three-layered chorion. The vitelline envelope is of the primary type while the chorion is of a secondary type. The surface of the chorion is covered with conical processes that terminate with a strongly indented terminal disc.

NASA's International Space Station: A Testbed for Planetary Protection Protocol Development

NASA Technical Reports Server (NTRS)

Bell, M. S.; Rucker, M.; Love, S.; Johnson, J.; Chambliss, J.; Pierson, D.; Ott, M.; Mary, N.; Glass, B.; Lupisella, M.;

Nasa's International Space Station: A Testbed for Planetary Protection Protocol Development

NASA Technical Reports Server (NTRS)

Bell, M. S.; Rucker, M.; Love, S.; Johnson, J.; Chambliss, J.; Pierson, D.; Ott, M.; Mary, N.; Glass, B.; Lupisella, M.;

MicroRNAs and phylogenomics resolve the relationships of Tardigrada and suggest that velvet worms are the sister group of Arthropoda

PubMed Central

Campbell, Lahcen I.; Rota-Stabelli, Omar; Edgecombe, Gregory D.; Marchioro, Trevor; Longhorn, Stuart J.; Telford, Maximilian J.; Philippe, Hervé; Rebecchi, Lorena; Peterson, Kevin J.; Pisani, Davide

2011-01-01

Morphological data traditionally group Tardigrada (water bears), Onychophora (velvet worms), and Arthropoda (e.g., spiders, insects, and their allies) into a monophyletic group of invertebrates with walking appendages known as the Panarthropoda. However, molecular data generally do not support the inclusion of tardigrades within the Panarthropoda, but instead place them closer to Nematoda (roundworms). Here we present results from the analyses of two independent genomic datasets, expressed sequence tags (ESTs) and microRNAs (miRNAs), which congruently resolve the phylogenetic relationships of Tardigrada. Our EST analyses, based on 49,023 amino acid sites from 255 proteins, significantly support a monophyletic Panarthropoda including Tardigrada and suggest a sister group relationship between Arthropoda and Onychophora. Using careful experimental manipulations—comparisons of model fit, signal dissection, and taxonomic pruning—we show that support for a Tardigrada + Nematoda group derives from the phylogenetic artifact of long-branch attraction. Our small RNA libraries fully support our EST results; no miRNAs were found to link Tardigrada and Nematoda, whereas all panarthropods were found to share one unique miRNA (miR-276). In addition, Onychophora and Arthropoda were found to share a second miRNA (miR-305). Our study confirms the monophyly of the legged ecdysozoans, shows that past support for a Tardigrada + Nematoda group was due to long-branch attraction, and suggests that the velvet worms are the sister group to the arthropods. PMID:21896763

Environmental Sequencing of Biotic Components of Dust in the Chihuahuan Desert

NASA Astrophysics Data System (ADS)

Walsh, E.; Gill, T. E.; Rivas, J. A., Jr.; Leung, M. Y.; Mohl, J.

2015-12-01

A growing number of studies mark the role of wind in dispersing biota. Most of these approaches have used traditional methods to assess taxonomic diversity. Here we used next generation sequencing to characterize microbiota in dust collected from the Chihuahuan Desert. Atmospheric dust was collected during events during 2011-2014 using dry deposition collectors placed at two sites in El Paso Co., TX. In parallel experiments, we rehydrated subsamples of dust and conducted PCR amplifications using conserved primers for 16S and 18S ribosomal genes. Sequenced reads were de-multiplexed, quality filtered, and processed using QIIME. Taxonomy was assigned based on pairwise identity using BLAST for microbial eukaryotes. All samples were rarefied to a set number of sequences per sample prior to downstream analyses. Bioinformatic analysis of four of the dust samples yielded a diversity of biota, including zooplankton, bacteria, fungi, algae, and protists, but fungi predominate (>90% of both 10K and 3K reads). In our rehydrations of dust samples from the U.S. southwest nematodes, gastrotrichs, tardigrades, monogonont and bdelloid rotifers, branchiopods and numerous ciliates have been recovered. Variability in genetic diversity among samples is based, in part, on the source and extent of the particular dust event. We anticipate the same patterns will be seen in the complete data set. These preliminary results indicate that wind is a major transporter of not only fungi, bacteria and other unicellular organisms but may also be important in shaping the distribution patterns of multi-cellular organisms such as those that inhabit aquatic environments in the arid southwestern US.

Distribution and Diversity of Soil Microfauna from East Antarctica: Assessing the Link between Biotic and Abiotic Factors

PubMed Central

Velasco-Castrillón, Alejandro; Schultz, Mark B.; Colombo, Federica; Gibson, John A. E.; Davies, Kerrie A.; Austin, Andrew D.; Stevens, Mark I.

2014-01-01

Terrestrial life in Antarctica has been described as some of the simplest on the planet, and mainly confined to soil microfaunal communities. Studies have suggested that the lack of diversity is due to extreme environmental conditions and thought to be driven by abiotic factors. In this study we investigated soil microfauna composition, abundance, and distribution in East Antarctica, and assessed correlations with soil geochemistry and environmental variables. We examined 109 soil samples from a wide range of ice-free habitats, spanning 2000 km from Framnes Mountains to Bailey Peninsula. Microfauna across all samples were patchily distributed, from complete absence of invertebrates to over 1600 specimens/gram of dry weight of soil (gdw), with highest microfauna abundance observed in samples with visible vegetation. Bdelloid rotifers were on average the most widespread found in 87% of sampled sites and the most abundant (44 specimens/gdw). Tardigrades occurred in 57% of the sampled sites with an abundance of 12 specimens/gdw. Nematodes occurred in 71% of samples with a total abundance of 3 specimens/gdw. Ciliates and mites were rarely found in soil samples, with an average abundance of 1.3 and 0.04 specimens/gdw, respectively. We found that microfaunal composition and abundance were mostly correlated with the soil geochemical parameters; phosphorus, NO3 − and salinity, and likely to be the result of soil properties and historic landscape formation and alteration, rather than the geographic region they were sampled from. Studies focusing on Antarctic biodiversity must take into account soil geochemical and environmental factors that influence population and species heterogeneity. PMID:24498126

Two new tardigrade species from Romania (Eutardigrada: Milnesiidae, Macrobiotidae), with some remarks on secondary sex characters in Milnesium dornensis sp. nov.

PubMed

Ciobanu, Daniel Adrian; Roszkowska, Milena; Kaczmarek, Łukasz

2015-04-02

In two moss and lichen samples collected in Romania, two new eutardigrade species were found. Milnesium dornensis sp. nov. belongs to the granulatum group and differs from most of other species in this group mainly by having a different claw configuration ([3-3]-[3-3]) and by some morphometric characters. Minibiotus diversus sp. nov. is very similar to M. gumersindoi Guil & Guidetti, 2005 and M. weglarskae Michalczyk et al., 2005, but differs from these and other congeners by the cuticular pore arrangement and morphometric characters of both adults and eggs. Males and females of the newly described Milnesium species differ not only by the shape and structure of claws I, but also by other morphometric characters. Males of Milnesium dornensis sp. nov. are smaller, more slender, have shorter papillae and relatively longer claws on legs III-IV.

Characterize Human Forward Contamination Project

NASA Technical Reports Server (NTRS)

Rucker, Michelle

2015-01-01

Let's face it: wherever we go, we will inevitably carry along the little critters that live in and on us. Conventional wisdom has long held that it's unlikely those critters could survive the space environment, but in 2007 microscopic animals called Tardigrades survived exposure to space and in 2008 Cyanobacteria lived for 548 days outside the International Space Station (ISS). But what about the organisms we might reasonably expect a crewed spacecraft to leak or vent? Do we even know what they are? How long might our tiny hitch-hikers survive in close proximity to a warm spacecraft that periodically leaks/vents water or oxygen-and how might they mutate with long-duration exposure? Unlike the Mars rovers that we cleaned once and sent on their way, crew members will provide a constantly regenerating contaminant source. Are we prepared to certify that we can meet forward contamination protocols as we search for life at new destinations? This project has four technical objectives: 1. TEST: Develop a test plan to leverage existing equipment (i.e. ISS) to characterize the kinds of organisms we can reasonably expect pressurized, crewed volumes to vent or leak overboard; 2. ANALYSIS: Develop an analysis plan to study those organisms in relevant destination environments, including spacecraft-induced conditions; 3. MODEL: Develop a modeling plan to model organism transport mechanisms in relevant destination environments; 4. SHARE: Develop a plan to disseminate findings and integrate recommendations into exploration requirements & ops. In short, we propose a system engineering approach to roadmap the necessary experiments, analysis, and modeling up front--rather than try to knit together disparate chunks of data into a sensible conclusion after the fact.

Survival of plant seeds, their UV screens, and nptII DNA for 18 months outside the International Space Station.

PubMed

Tepfer, David; Zalar, Andreja; Leach, Sydney

2012-05-01

The plausibility that life was imported to Earth from elsewhere can be tested by subjecting life-forms to space travel. Ultraviolet light is the major liability in short-term exposures (Horneck et al., 2001 ), and plant seeds, tardigrades, and lichens-but not microorganisms and their spores-are candidates for long-term survival (Anikeeva et al., 1990 ; Sancho et al., 2007 ; Jönsson et al., 2008 ; de la Torre et al., 2010 ). In the present study, plant seeds germinated after 1.5 years of exposure to solar UV, solar and galactic cosmic radiation, temperature fluctuations, and space vacuum outside the International Space Station. Of the 2100 exposed wild-type Arabidopsis thaliana and Nicotiana tabacum (tobacco) seeds, 23% produced viable plants after return to Earth. Survival was lower in the Arabidopsis Wassilewskija ecotype and in mutants (tt4-8 and fah1-2) lacking UV screens. The highest survival occurred in tobacco (44%). Germination was delayed in seeds shielded from solar light, yet full survival was attained, which indicates that longer space travel would be possible for seeds embedded in an opaque matrix. We conclude that a naked, seed-like entity could have survived exposure to solar UV radiation during a hypothetical transfer from Mars to Earth. Chemical samples of seed flavonoid UV screens were degraded by UV, but their overall capacity to absorb UV was retained. Naked DNA encoding the nptII gene (kanamycin resistance) was also degraded by UV. A fragment, however, was detected by the polymerase chain reaction, and the gene survived in space when protected from UV. Even if seeds do not survive, components (e.g., their DNA) might survive transfer over cosmic distances.

An integrated approach to fast and informative morphological vouchering of nematodes for applications in molecular barcoding

PubMed Central

De Ley, Paul; De Ley, Irma Tandingan; Morris, Krystalynne; Abebe, Eyualem; Mundo-Ocampo, Manuel; Yoder, Melissa; Heras, Joseph; Waumann, Dora; Rocha-Olivares, Axayácatl; Jay Burr, A.H; Baldwin, James G; Thomas, W. Kelley

2005-01-01

Molecular surveys of meiofaunal diversity face some interesting methodological challenges when it comes to interstitial nematodes from soils and sediments. Morphology-based surveys are greatly limited in processing speed, while barcoding approaches for nematodes are hampered by difficulties of matching sequence data with traditional taxonomy. Intermediate technology is needed to bridge the gap between both approaches. An example of such technology is video capture and editing microscopy, which consists of the recording of taxonomically informative multifocal series of microscopy images as digital video clips. The integration of multifocal imaging with sequence analysis of the D2D3 region of large subunit (LSU) rDNA is illustrated here in the context of a combined morphological and barcode sequencing survey of marine nematodes from Baja California and California. The resulting video clips and sequence data are made available online in the database NemATOL (http://nematol.unh.edu/). Analyses of 37 barcoded nematodes suggest that these represent at least 32 species, none of which matches available D2D3 sequences in public databases. The recorded multifocal vouchers allowed us to identify most specimens to genus, and will be used to match specimens with subsequent species identifications and descriptions of preserved specimens. Like molecular barcodes, multifocal voucher archives are part of a wider effort at structuring and changing the process of biodiversity discovery. We argue that data-rich surveys and phylogenetic tools for analysis of barcode sequences are an essential component of the exploration of phyla with a high fraction of undiscovered species. Our methods are also directly applicable to other meiofauna such as for example gastrotrichs and tardigrades. PMID:16214752

Planetary and Space Simulation Facilities PSI at DLR for Astrobiology

NASA Astrophysics Data System (ADS)

Rabbow, E.; Rettberg, P.; Panitz, C.; Reitz, G.

2008-09-01

Ground based experiments, conducted in the controlled planetary and space environment simulation facilities PSI at DLR, are used to investigate astrobiological questions and to complement the corresponding experiments in LEO, for example on free flying satellites or on space exposure platforms on the ISS. In-orbit exposure facilities can only accommodate a limited number of experiments for exposure to space parameters like high vacuum, intense radiation of galactic and solar origin and microgravity, sometimes also technically adapted to simulate extraterrestrial planetary conditions like those on Mars. Ground based experiments in carefully equipped and monitored simulation facilities allow the investigation of the effects of simulated single environmental parameters and selected combinations on a much wider variety of samples. In PSI at DLR, international science consortia performed astrobiological investigations and space experiment preparations, exposing organic compounds and a wide range of microorganisms, reaching from bacterial spores to complex microbial communities, lichens and even animals like tardigrades to simulated planetary or space environment parameters in pursuit of exobiological questions on the resistance to extreme environments and the origin and distribution of life. The Planetary and Space Simulation Facilities PSI of the Institute of Aerospace Medicine at DLR in Köln, Germany, providing high vacuum of controlled residual composition, ionizing radiation of a X-ray tube, polychromatic UV radiation in the range of 170-400 nm, VIS and IR or individual monochromatic UV wavelengths, and temperature regulation from -20°C to +80°C at the sample size individually or in selected combinations in 9 modular facilities of varying sizes are presented with selected experiments performed within.

Observed trends of soil fauna in the Antarctic Dry Valleys: early signs of shifts predicted under climate change.

PubMed

Andriuzzi, W S; Adams, B J; Barrett, J E; Virginia, R A; Wall, D H

2018-02-01

Long-term observations of ecological communities are necessary for generating and testing predictions of ecosystem responses to climate change. We investigated temporal trends and spatial patterns of soil fauna along similar environmental gradients in three sites of the McMurdo Dry Valleys, Antarctica, spanning two distinct climatic phases: a decadal cooling trend from the early 1990s through the austral summer of February 2001, followed by a shift to the current trend of warming summers and more frequent discrete warming events. After February 2001, we observed a decline in the dominant species (the nematode Scottnema lindsayae) and increased abundance and expanded distribution of less common taxa (rotifers, tardigrades, and other nematode species). Such diverging responses have resulted in slightly greater evenness and spatial homogeneity of taxa. However, total abundance of soil fauna appears to be declining, as positive trends of the less common species so far have not compensated for the declining numbers of the dominant species. Interannual variation in the proportion of juveniles in the dominant species was consistent across sites, whereas trends in abundance varied more. Structural equation modeling supports the hypothesis that the observed biological trends arose from dissimilar responses by dominant and less common species to pulses of water availability resulting from enhanced ice melt. No direct effects of mean summer temperature were found, but there is evidence of indirect effects via its weak but significant positive relationship with soil moisture. Our findings show that combining an understanding of species responses to environmental change with long-term observations in the field can provide a context for validating and refining predictions of ecological trends in the abundance and diversity of soil fauna. © 2018 by the Ecological Society of America.

Cytochrome P450 diversity in the tree of life.

PubMed

Nelson, David R

2018-01-01

Sequencing in all areas of the tree of life has produced >300,000 cytochrome P450 (CYP) sequences that have been mined and collected. Nomenclature has been assigned to >41,000 CYP sequences and the majority of the remainder has been sorted by BLAST searches into clans, families and subfamilies in preparation for naming. The P450 sequence space is being systematically explored and filled in. Well-studied groups like vertebrates are covered in greater depth while new insights are being added into uncharted territories like horseshoe crab (Limulus polyphemus), tardigrades (Hypsibius dujardini), velvet worm (Euperipatoides_rowelli), and basal land plants like hornworts, liverworts and mosses. CYPs from the fungi, one of the most diverse groups, are being explored and organized as nearly 800 fungal species are now sequenced. The CYP clan structure in fungi is emerging with 805 CYP families sorting into 32 CYP clans. >3000 bacterial sequences are named, mostly from terrestrial or freshwater sources. Of 18,379 bacterial sequences downloaded from the CYPED database, all are >43% identical to named CYPs. Therefore, they fit in the 602 named P450 prokaryotic families. Diversity in this group is becoming saturated, however 25% of 3305 seawater bacterial P450s did not match known P450 families, indicating marine bacterial CYPs are not as well sampled as land/freshwater based bacterial CYPs. Future sequencing plans of the Genome 10K project, i5k and GIGA (Global Invertebrate Genomics Alliance) are expected to produce more than one million cytochrome P450 sequences by 2020. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone. Copyright © 2017 Elsevier B.V. All rights reserved.

Environmental DNA sequencing primers for eutardigrades and bdelloid rotifers

PubMed Central

2009-01-01

Background The time it takes to isolate individuals from environmental samples and then extract DNA from each individual is one of the problems with generating molecular data from meiofauna such as eutardigrades and bdelloid rotifers. The lack of consistent morphological information and the extreme abundance of these classes makes morphological identification of rare, or even common cryptic taxa a large and unwieldy task. This limits the ability to perform large-scale surveys of the diversity of these organisms. Here we demonstrate a culture-independent molecular survey approach that enables the generation of large amounts of eutardigrade and bdelloid rotifer sequence data directly from soil. Our PCR primers, specific to the 18s small-subunit rRNA gene, were developed for both eutardigrades and bdelloid rotifers. Results The developed primers successfully amplified DNA of their target organism from various soil DNA extracts. This was confirmed by both the BLAST similarity searches and phylogenetic analyses. Tardigrades showed much better phylogenetic resolution than bdelloids. Both groups of organisms exhibited varying levels of endemism. Conclusion The development of clade-specific primers for characterizing eutardigrades and bdelloid rotifers from environmental samples should greatly increase our ability to characterize the composition of these taxa in environmental samples. Environmental sequencing as shown here differs from other molecular survey methods in that there is no need to pre-isolate the organisms of interest from soil in order to amplify their DNA. The DNA sequences obtained from methods that do not require culturing can be identified post-hoc and placed phylogenetically as additional closely related sequences are obtained from morphologically identified conspecifics. Our non-cultured environmental sequence based approach will be able to provide a rapid and large-scale screening of the presence, absence and diversity of Bdelloidea and Eutardigrada in

An integrative description of Macrobiotus shonaicus sp. nov. (Tardigrada: Macrobiotidae) from Japan with notes on its phylogenetic position within the hufelandi group

PubMed Central

Stec, Daniel; Arakawa, Kazuharu

2018-01-01

Tardigrade research in Japan dates back over 100 years, and to date, 167 species of this ecdysozoan phylum have been reported from the country. Of these species, the Macrobiotus hufelandi complex has been represented only by the nominal taxon of this group, Macrobiotus hufelandi. In this article, a new species of the hufelandi group from Japan, Macrobiotus shonaicus sp. nov., is described using integrative taxonomy. In addition to the detailed morphological and morphometric data, obtained using phase contrast light microscopy (PCM) and scanning electron microscopy (SEM), we provide DNA sequences of four molecular markers (both nuclear and mitochondrial). The new species belongs to the persimilis subgroup and is most similar to M. anemone from USA, M. naskreckii from Mozambique, and M. patagonicus from Argentina, but it can be easily distinguished from these species by the presence of thin flexible filaments on terminal discs of the egg process. By the latter character, the new species is most similar to M. paulinae and M. polypiformis, but it can be easily distinguished from them by having a solid egg surface between egg processes (i.e., without pores or reticulum). A phylogenetic analysis of available DNA sequences of the COI marker for the hufelandi group revealed that the new species clusters with the two other species that exhibit filaments on egg process discs (M. paulinae and M. polypiformis) and with two species that have entire egg processes modified into filaments (M. kristenseni and M. scoticus). All five species form a clade distinct from all other sequenced species of the hufelandi group with typical mushroom- or inverted goblet-shaped egg processes, which may suggest that the ancestor of the five species with atypical egg processes had a mutation allowing derivations from the mushroom or inverted chalice-like shape of egg processes. PMID:29489835

Controls on microalgal community structures in cryoconite holes upon high-Arctic glaciers, Svalbard

NASA Astrophysics Data System (ADS)

Vonnahme, T. R.; Devetter, M.; Žárský, J. D.; Šabacká, M.; Elster, J.

2016-02-01

Glaciers are known to harbor surprisingly complex ecosystems. On their surface, distinct cylindrical holes filled with meltwater and sediments are considered hot spots for microbial life. The present paper addresses possible biological interactions within the community of prokaryotic cyanobacteria and eukaryotic microalgae (microalgae) and relations to their potential grazers, such as tardigrades and rotifers, additional to their environmental controls. Svalbard glaciers with substantial allochthonous input of material from local sources reveal high microalgal densities. Small valley glaciers with high sediment coverages and high impact of birds show high biomasses and support a high biological diversity. Invertebrate grazer densities do not show any significant negative correlation with microalgal abundances but rather a positive correlation with eukaryotic microalgae. Shared environmental preferences and a positive effect of grazing are the proposed mechanisms to explain these correlations. Most microalgae found in this study form colonies (< 10 cells, or > 25 µm), which may protect them against invertebrate grazing. This finding rather indicates grazing as a positive control on eukaryotic microalgae by nutrient recycling. Density differences between the eukaryotic microalgae and prokaryotic cyanobacteria and their high distinction in redundancy (RDA) and principal component (PCA) analyses indicate that these two groups are in strong contrast. Eukaryotic microalgae occurred mainly in unstable cryoconite holes with high sediment loads, high N : P ratios, and a high impact of nutrient input by bird guano, as a proxy for nutrients. In these environments autochthonous nitrogen fixation appears to be negligible. Selective wind transport of Oscillatoriales via soil and dust particles is proposed to explain their dominance in cryoconites further away from the glacier margins. We propose that, for the studied glaciers, nutrient levels related to recycling of limiting

Characterize Human Forward Contamination Project

NASA Technical Reports Server (NTRS)

Rucker, Michelle

2015-01-01

Let's face it: wherever we go, we will inevitably carry along the little critters that live in and on us. Conventional wisdom has long held that it's unlikely those critters could survive the space environment, but in 2007 microscopic animals called Tardigrades survived exposure to space and in 2008 Cyanobacteria lived for 548 days outside the International Space Station (ISS). But what about the organisms we might reasonably expect a crewed spacecraft to leak or vent? Do we even know what they are? How long might our tiny hitch-hikers survive in close proximity to a warm spacecraft that periodically leaks/vents water or oxygen-and how might they mutate with long-duration exposure? Unlike the Mars rovers that we cleaned once and sent on their way, crew members will provide a constantly regenerating contaminant source. Are we prepared to certify that we can meet forward contamination protocols as we search for life at new destinations? This project has four technical objectives: 1. TEST: Develop a test plan to leverage existing equipment (i.e. ISS) to characterize the kinds of organisms we can reasonably expect pressurized, crewed volumes to vent or leak overboard; as part of testing, we'll need to develop an Extravehicular Activity (EVA)-compatible tool that can withstand the pressure and temperature extremes of space, as well as collect, separate, and store multiple samples; 2. ANALYSIS: Develop an analysis plan to study those organisms in relevant destination environments, including spacecraft-induced conditions; 3. MODEL: Develop a modeling plan to model organism transport mechanisms in relevant destination environments; 4. SHARE: Develop a plan to disseminate findings and integrate recommendations into exploration requirements & ops. In short, we propose a system engineering approach to roadmap the necessary experiments, analysis, and modeling up front--rather than try to knit together disparate chunks of data into a sensible conclusion after the fact.

Effects of human trampling on populations of soil fauna in the McMurdo Dry Valleys, Antarctica.

PubMed

Ayres, Edward; Nkem, Johnson N; Wall, Diana H; Adams, Byron J; Barrett, J E; Broos, Emma J; Parsons, Andrew N; Powers, Laura E; Simmons, Breana L; Virginia, Ross A

2008-12-01

Antarctic ecosystems are often considered nearly pristine because levels of anthropogenic disturbance are extremely low there. Nevertheless, over recent decades there has been a rapid increase in the number of people, researchers and tourists, visiting Antarctica. We evaluated, over 10 years, the direct impact of foot traffic on the abundance of soil animals and soil properties in Taylor Valley within the McMurdo Dry Valleys region of Antarctica. We compared soils from minimally disturbed areas with soils from nearby paths that received intermediate and high levels of human foot traffic (i.e., up to approximately 80 passes per year). The nematodes Scottnema lindsayae and Eudorylaimus sp. were the most commonly found animal species, whereas rotifers and tardigrades were found only occasionally. On the highly trampled footpaths, abundance of S. lindsayae and Eudorylaimus sp. was up to 52 and 76% lower, respectively, than in untrampled areas. Moreover, reduction in S. lindsayae abundance was more pronounced after 10 years than 2 years and in the surface soil than in the deeper soil, presumably because of the longer period of disturbance and the greater level of physical disturbance experienced by the surface soil. The ratio of living to dead Eudorylaimus sp. also declined with increased trampling intensity, which is indicative of increased mortality or reduced fecundity. At one site there was evidence that high levels of trampling reduced soil CO(2) fluxes, which is related to total biological activity in the soil. Our results show that even low levels of human traffic can significantly affect soil biota in this ecosystem and may alter ecosystem processes, such as carbon cycling. Consequently, management and conservation plans for Antarctic soils should consider the high sensitivity of soil fauna to physical disturbance as human presence in this ecosystem increases.

An integrative description of Macrobiotus shonaicus sp. nov. (Tardigrada: Macrobiotidae) from Japan with notes on its phylogenetic position within the hufelandi group.

PubMed

Stec, Daniel; Arakawa, Kazuharu; Michalczyk, Łukasz

2018-01-01

Tardigrade research in Japan dates back over 100 years, and to date, 167 species of this ecdysozoan phylum have been reported from the country. Of these species, the Macrobiotus hufelandi complex has been represented only by the nominal taxon of this group, Macrobiotus hufelandi. In this article, a new species of the hufelandi group from Japan, Macrobiotus shonaicus sp. nov., is described using integrative taxonomy. In addition to the detailed morphological and morphometric data, obtained using phase contrast light microscopy (PCM) and scanning electron microscopy (SEM), we provide DNA sequences of four molecular markers (both nuclear and mitochondrial). The new species belongs to the persimilis subgroup and is most similar to M. anemone from USA, M. naskreckii from Mozambique, and M. patagonicus from Argentina, but it can be easily distinguished from these species by the presence of thin flexible filaments on terminal discs of the egg process. By the latter character, the new species is most similar to M. paulinae and M. polypiformis, but it can be easily distinguished from them by having a solid egg surface between egg processes (i.e., without pores or reticulum). A phylogenetic analysis of available DNA sequences of the COI marker for the hufelandi group revealed that the new species clusters with the two other species that exhibit filaments on egg process discs (M. paulinae and M. polypiformis) and with two species that have entire egg processes modified into filaments (M. kristenseni and M. scoticus). All five species form a clade distinct from all other sequenced species of the hufelandi group with typical mushroom- or inverted goblet-shaped egg processes, which may suggest that the ancestor of the five species with atypical egg processes had a mutation allowing derivations from the mushroom or inverted chalice-like shape of egg processes.

Ultrastructural changes and programmed cell death of trophocytes in the gonad of Isohypsibius granulifer granulifer Thulin, 1928 (Tardigrada, Eutardigrada, Isohypsibiidae).

PubMed

Poprawa, Izabela; Hyra, Marta; Kszuk-Jendrysik, Michalina; Rost-Roszkowska, Magdalena Maria

2015-03-01

The studies on the fates of the trophocytes, the apoptosis and autophagy in the gonad of Isohypsibius granulifer granulifer have been described using transmission electron microscope, light and fluorescent microscopes. The results presented here are the first that are connected with the cell death of nurse cells in the gonad of tardigrades. However, here we complete the results presented by Węglarska (1987). The reproductive system of I. g. granulifer contains a single sack-like hermaphroditic gonad and a single gonoduct. The gonad is composed of three parts: a germarium filled with proliferating germ cells (oogonia); a vitellarium that has clusters of female germ cells (the region of oocytes development); and a male part filled with male germ cells in which the sperm cells develop. The trophocytes (nurse cells) show distinct alterations during all of the stages of oogenesis: previtello-, vitello- and choriogenesis. During previtellogenesis the female germ cells situated in the vitellarium are connected by cytoplasmic bridges, and form clusters of cells. No ultrastructural differences appear among the germ cells in a cluster during this stage of oogenesis. In early vitellogenesis, the cells in each cluster start to grow and numerous organelles gradually accumulate in their cytoplasm. However, at the beginning of the middle of vitellogenesis, one cell in each cluster starts to grow in order to differentiate into oocyte, while the remaining cells are trophocytes. Eventually, the cytoplasmic bridges between the oocyte and trophocytes disappear. Autophagosomes also appear in the cytoplasm of nurse cells together with many degenerating organelles. The cytoplasm starts to shrink, which causes the degeneration of the cytoplasmic bridges between trophocytes. Apoptosis begins when the cytoplasm of these cells is full of autophagosomes/autolysosomes and causes their death. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ancestral Patterning of Tergite Formation in a Centipede Suggests Derived Mode of Trunk Segmentation in Trilobites

PubMed Central

Ortega-Hernández, Javier; Brena, Carlo

2012-01-01

Trilobites have a rich and abundant fossil record, but little is known about the intrinsic mechanisms that orchestrate their body organization. To date, there is disagreement regarding the correspondence, or lack thereof, of the segmental units that constitute the trilobite trunk and their associated exoskeletal elements. The phylogenetic position of trilobites within total-group Euarthropoda, however, allows inferences about the underlying organization in these extinct taxa to be made, as some of the fundamental genetic processes for constructing the trunk segments are remarkably conserved among living arthropods. One example is the expression of the segment polarity gene engrailed, which at embryonic and early postembryonic stages is expressed in extant panarthropods (i.e. tardigrades, onychophorans, euarthropods) as transverse stripes that define the posteriormost region of each trunk segment. Due to its conservative morphology and allegedly primitive trunk tagmosis, we have utilized the centipede Strigamia maritima to study the correspondence between the expression of engrailed during late embryonic to postembryonic stages, and the development of the dorsal exoskeletal plates (i.e. tergites). The results corroborate the close correlation between the formation of the tergite borders and the dorsal expression of engrailed, and suggest that this association represents a symplesiomorphy within Euarthropoda. This correspondence between the genetic and phenetic levels enables making accurate inferences about the dorsoventral expression domains of engrailed in the trunk of exceptionally preserved trilobites and their close relatives, and is suggestive of the widespread occurrence of a distinct type of genetic segmental mismatch in these extinct arthropods. The metameric organization of the digestive tract in trilobites provides further support to this new interpretation. The wider evolutionary implications of these findings suggest the presence of a derived

Tree species traits influence soil physical, chemical, and biological properties in high elevation forests.

PubMed

Ayres, Edward; Steltzer, Heidi; Berg, Sarah; Wallenstein, Matthew D; Simmons, Breana L; Wall, Diana H

2009-06-18

Previous studies have shown that plants often have species-specific effects on soil properties. In high elevation forests in the Southern Rocky Mountains, North America, areas that are dominated by a single tree species are often adjacent to areas dominated by another tree species. Here, we assessed soil properties beneath adjacent stands of trembling aspen, lodgepole pine, and Engelmann spruce, which are dominant tree species in this region and are distributed widely in North America. We hypothesized that soil properties would differ among stands dominated by different tree species and expected that aspen stands would have higher soil temperatures due to their open structure, which, combined with higher quality litter, would result in increased soil respiration rates, nitrogen availability, and microbial biomass, and differences in soil faunal community composition. We assessed soil physical, chemical, and biological properties at four sites where stands of aspen, pine, and spruce occurred in close proximity to one-another in the San Juan Mountains, Colorado. Leaf litter quality differed among the tree species, with the highest nitrogen (N) concentration and lowest lignin:N in aspen litter. Nitrogen concentration was similar in pine and spruce litter, but lignin:N was highest in pine litter. Soil temperature and moisture were highest in aspen stands, which, in combination with higher litter quality, probably contributed to faster soil respiration rates from stands of aspen. Soil carbon and N content, ammonium concentration, and microbial biomass did not differ among tree species, but nitrate concentration was highest in aspen soil and lowest in spruce soil. In addition, soil fungal, bacterial, and nematode community composition and rotifer, collembolan, and mesostigmatid mite abundance differed among the tree species, while the total abundance of nematodes, tardigrades, oribatid mites, and prostigmatid mites did not. Although some soil characteristics were

Utilizing ARC EMCS Seedling Cassettes as Highly Versatile Miniature Growth Chambers for Model Organism Experiments

NASA Technical Reports Server (NTRS)

Freeman, John L.; Steele, Marianne K.; Sun, Gwo-Shing; Heathcote, David; Reinsch, S.; DeSimone, Julia C.; Myers, Zachary A.

2014-01-01

The aim of our ground testing was to demonstrate the capability of safely putting specific model organisms into dehydrated stasis, and to later rehydrate and successfully grow them inside flight proven ARC EMCS seedling cassettes. The ARC EMCS seedling cassettes were originally developed to support seedling growth during space flight. The seeds are attached to a solid substrate, launched dry, and then rehydrated in a small volume of media on orbit to initiate the experiment. We hypothesized that the same seedling cassettes should be capable of acting as culture chambers for a wide range of organisms with minimal or no modification. The ability to safely preserve live organisms in a dehydrated state allows for on orbit experiments to be conducted at the best time for crew operations and more importantly provides a tightly controlled physiologically relevant growth experiment with specific environmental parameters. Thus, we performed a series of ground tests that involved growing the organisms, preparing them for dehydration on gridded Polyether Sulfone (PES) membranes, dry storage at ambient temperatures for varying periods of time, followed by rehydration. Inside the culture cassettes, the PES membranes were mounted above blotters containing dehydrated growth media. These were mounted on stainless steel bases and sealed with plastic covers that have permeable membrane covered ports for gas exchange. The results showed we were able to demonstrate acceptable normal growth of C.elegans (nematodes), E.coli (bacteria), S.cerevisiae (yeast), Polytrichum (moss) spores and protonemata, C.thalictroides (fern), D.discoideum (amoeba), and H.dujardini (tardigrades). All organisms showed acceptable growth and rehydration in both petri dishes and culture cassettes initially, and after various time lengths of dehydration. At the end of on orbit ISS European Modular Cultivation System experiments the cassettes could be frozen at ultra-low temperatures, refrigerated, or chemically

Capturing Evidence for Past Life in the Martian Loess

NASA Astrophysics Data System (ADS)

Schultz, P. H.; Harris, R. S.; Clemett, S. J.; Thomas-Keprta, K. L.; Zárate, M.

2014-12-01

Vast loess deposits in Europe and the US accumulated after the last glacial maxima (<20 kyrs). In Argentina, however, they gradually accumulated from dried riverbeds that carried sediments from the Andes over the last 12 myrs [1]. These 300m-thick loessoid deposits resemble the accumulations of unconformable deposits found on Mars, some exceeding 3km in thickness. While short-lived as surface materials on the Earth (e.g., <12 myrs in Argentina), they remain exposed for billions of years on Mars (since the Late Noachian). Unlithified loessoid deposits represent a special target type affecting both crater excavation and melt generation. Craters as large as 20km in diameter may not reach the underlying "basement" (e.g., cratered highlands). Porous targets also result in greater amounts of impact melt derived from different levels [2, 3]. Moreover, melt breccias can be soft captured, buried, and trapped until re-exposed [4]. In Argentina, some folded vesicular glasses as old as 9.3 myrs contain flash-heated yet well-preserved biomatter (down to < 5 microns) including plant materials [5] and even partially vitrified cartilage fragments [6]. The entrained plant materials also contain organic relicts such as derivatives of chlorophyll. This biomatter becomes trapped as the melt is rolled and folded during excavation or emplacement. Exploratory impact experiments at the NASA Ames Vertical Gun Range simulated this process at a much smaller scale (5km/s at 45 deg impact angle). Fragments of wetted Pampas grass and tardigrades buried near the surface were entrained within small, twisted and folded glasses. Grass positioned uprange of the impact, however, survived intact within a projectile radius of the impact point. Consequently, the low impact speeds available in the experiments could be more than offset by an uprange location for a much higher speed impact. While plant material should not be expected, other primitive forms could be mixed within seams and folds within

Cell-in-Shell Hybrids: Chemical Nanoencapsulation of Individual Cells.

PubMed

Park, Ji Hun; Hong, Daewha; Lee, Juno; Choi, Insung S

2016-05-17

Nature has developed a fascinating strategy of cryptobiosis ("secret life") for counteracting the stressful, and often lethal, environmental conditions that fluctuate sporadically over time. For example, certain bacteria sporulate to transform from a metabolically active, vegetative state to an ametabolic endospore state. The bacterial endospores, encased within tough biomolecular shells, withstand the extremes of harmful stressors, such as radiation, desiccation, and malnutrition, for extended periods of time and return to a vegetative state by breaking their protective shells apart when their environment becomes hospitable for living. Certain ciliates and even higher organisms, for example, tardigrades, and others are also found to adopt a cryptobiotic strategy for survival. A common feature of cryptobiosis is the structural presence of tough sheaths on cellular structures. However, most cells and cellular assemblies are not "spore-forming" and are vulnerable to the outside threats. In particular, mammalian cells, enclosed with labile lipid bilayers, are highly susceptible to in vitro conditions in the laboratory and daily life settings, making manipulation and preservation difficult outside of specialized conditions. The instability of living cells has been a main bottleneck to the advanced development of cell-based applications, such as cell therapy and cell-based sensors. A judicious question arises: can cellular tolerance against harmful stresses be enhanced by simply forming cell-in-shell hybrid structures? Experimental results suggest that the answer is yes. A micrometer-sized "Iron Man" can be generated by chemically forming an ultrathin (<100 nm) but durable shell on a "non-spore-forming" cell. Since the report on silica nanoencapsulation of yeast cells, in which cytoprotective yeast-in-silica hybrids were formed, several synthetic strategies have been developed to encapsulate individual cells in a cytocompatible fashion, mimicking the cryptobiotic cell