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Mäenpää H, Elo M, Calhim S. A first look into moss living tardigrades in boreal peatlands. Ecol Evol 2024; 14:e70045. [PMID: 39091332 PMCID: PMC11293882 DOI: 10.1002/ece3.70045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/28/2024] [Accepted: 07/08/2024] [Indexed: 08/04/2024] Open
Abstract
Tardigrades (Tardigrada) are a phylum of micrometazoans found in all biomes on Earth, but their ecology and habitat preferences remain vastly understudied. Boreal peatlands include a diversity of habitat types and high structural heterogeneity that represents an interesting system to study some of the poorly known habitat preferences of tardigrades. Here, we investigate for the first time tardigrade communities in peatland mosses and the latter's potential associations with key environmental variables. We collected 116 moss samples from 13 sites representing different peatland types and management histories. We found that tardigrades are common and diverse in boreal peatlands, as tardigrades were present in 72% of the collected samples and we identified 14 tardigrade genera. Tardigrade abundance seemed to increase alongside the increasing tree basal area and the density was higher in the microtopographic level further from the water table level, that is, hummocks (mean 117/moss gram) than in lawns/hollows (mean 84/moss gram). Furthermore, the highest tardigrade density was found in the moss taxa that are associated with forested peatland types (i.e., feather mosses) (321 mean/moss gram). Finally, we found interesting patterns regarding tardigrade functional diversity, as carnivorous tardigrades were found only in peatlands with tree basal area > 20 m2 and mostly in hummocks. Our study demonstrates that the habitat heterogeneity of peatlands (e.g., variation in moisture and vegetation cover) represents an interesting system to study tardigrade ecology and habitat preferences. However, since we found variation in tardigrade abundance and communities across peatland types and microhabitats within peatlands, our results highlight that such studies should be conducted with numerous replicate samples and a systematic study design that properly addresses the habitat heterogeneity between and within different peatland types.
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Affiliation(s)
- Hennariikka Mäenpää
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
| | - Merja Elo
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
- Nature Solutions UnitFinnish Environment InstituteJyväskyläFinland
| | - Sara Calhim
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland
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2
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Kirk MJ, Xu C, Rothman JH. Single-animal, single-tube RNA extraction for quantitative analysis of transcripts in the tardigrade Hypsibius exemplaris. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.15.585302. [PMID: 38559134 PMCID: PMC10979942 DOI: 10.1101/2024.03.15.585302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The tardigrade Hypsibius exemplaris is an emerging model organism renowned for its ability to survive environmental extremes.1-3 To explore the molecular mechanisms and genetic basis of such extremotolerance, many studies rely on transcriptional profiling4, 5 and RNA interference (RNAi)6 to define molecular targets. Such studies require efficient, accurate, and robust RNA extraction methods; however, obtaining high-quality quantitative levels of RNA from H. exemplaris has been challenging6, 7. Possessing a layer of firm chitinous cuticle, tardigrade tissues are difficult to disrupt by chemical or mechanical means8. Here we present an efficient single-tardigrade, single-tube RNA extraction method (STST) that not only reliably isolates RNA from individual tardigrades but dramatically reduces the time required for extraction. We show that this RNA extraction method yields robust quantities of cDNA and can be used to amplify multiple transcripts by qRT-PCR. To validate the method, we use it to compare dynamic changes in expression of genes encoding two heat-shock-regulated proteins, Heat-Shock Protein 70 β2 (HSP70β2) and Heat-Shock Protein 90α (HSP90α) by quantifying their expression levels in heat-exposed and cold-exposed individuals using qRT-PCR across long-term and short-term heat stressors. Our method effectively complements existing bulk RNA extraction methods7, permitting rapid examination of individual tardigrade transcriptional data and quantification of phenotypic variations in expression profiles amongst individuals.
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Affiliation(s)
- Molly J. Kirk
- Department of Molecular Cellular and Developmental Biology University of California, Santa Barbara, Santa Barbara, CA
| | - Chaoming Xu
- Department of Molecular Cellular and Developmental Biology University of California, Santa Barbara, Santa Barbara, CA
| | - Joel H. Rothman
- Department of Molecular Cellular and Developmental Biology University of California, Santa Barbara, Santa Barbara, CA
- Neuroscience Research Institute, University of California, Santa Barbara, Santa Barbara, CA
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3
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Kayastha P, Wieczorkiewicz F, Pujol M, Robinson A, Michalak M, Kaczmarek Ł, Poprawa I. Elevated external temperature affects cell ultrastructure and heat shock proteins (HSPs) in Paramacrobiotus experimentalis Kaczmarek, Mioduchowska, Poprawa, & Roszkowska, 2020. Sci Rep 2024; 14:5097. [PMID: 38429316 PMCID: PMC10907573 DOI: 10.1038/s41598-024-55295-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 02/22/2024] [Indexed: 03/03/2024] Open
Abstract
Increasing temperature influences the habitats of various organisms, including microscopic invertebrates. To gain insight into temperature-dependent changes in tardigrades, we isolated storage cells exposed to various temperatures and conducted biochemical and ultrastructural analysis in active and tun-state Paramacrobiotus experimentalis Kaczmarek, Mioduchowska, Poprawa, & Roszkowska, 2020. The abundance of heat shock proteins (HSPs) and ultrastructure of the storage cells were examined at different temperatures (20 °C, 30 °C, 35 °C, 37 °C, 40 °C, and 42 °C) in storage cells isolated from active specimens of Pam. experimentalis. In the active animals, upon increase in external temperature, we observed an increase in the levels of HSPs (HSP27, HSP60, and HSP70). Furthermore, the number of ultrastructural changes in storage cells increased with increasing temperature. Cellular organelles, such as mitochondria and the rough endoplasmic reticulum, gradually degenerated. At 42 °C, cell death occurred by necrosis. Apart from the higher electron density of the karyoplasm and the accumulation of electron-dense material in some mitochondria (at 42 °C), almost no changes were observed in the ultrastructure of tun storage cells exposed to different temperatures. We concluded that desiccated (tun-state) are resistant to high temperatures, but not active tardigrades (survival rates of tuns after 24 h of rehydration: 93.3% at 20 °C, 60.0% at 35 °C, 33.3% at 37 °C, 33.3% at 40 °C, and 20.0% at 42 °C).
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Affiliation(s)
- Pushpalata Kayastha
- Department of Animal Taxonomy and Ecology, Faculty of Biology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland.
| | - Filip Wieczorkiewicz
- Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Bankowa 9, 40-007, Katowice, Poland
| | - Myriam Pujol
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Alison Robinson
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Marek Michalak
- Department of Biochemistry, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Łukasz Kaczmarek
- Department of Animal Taxonomy and Ecology, Faculty of Biology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, 61-614, Poznań, Poland
| | - Izabela Poprawa
- Institute of Biology, Biotechnology and Environmental Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Bankowa 9, 40-007, Katowice, Poland.
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4
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Al-Ansari M, Fitzsimons T, Wei W, Goldberg MW, Kunieda T, Quinlan RA. The major inducible small heat shock protein HSP20-3 in the tardigrade Ramazzottius varieornatus forms filament-like structures and is an active chaperone. Cell Stress Chaperones 2024; 29:51-65. [PMID: 38330543 PMCID: PMC10939073 DOI: 10.1016/j.cstres.2023.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 12/03/2023] [Indexed: 02/10/2024] Open
Abstract
The tardigrade Ramazzottius varieornatus has remarkable resilience to a range of environmental stresses. In this study, we have characterised two members of the small heat shock protein (sHSP) family in R. varieornatus, HSP20-3 and HSP20-6. These are the most highly upregulated sHSPs in response to a 24 h heat shock at 35 0C of adult tardigrades with HSP20-3 being one of the most highly upregulated gene in the whole transcriptome. Both R. varieornatus sHSPs and the human sHSP, CRYAB (HSPB5), were produced recombinantly for comparative structure-function studies. HSP20-3 exhibited a superior chaperone activity than human CRYAB in a heat-induced protein aggregation assay. Both tardigrade sHSPs also formed larger oligomers than CRYAB as assessed by size exclusion chromatography and transmission electron microscopy of negatively stained samples. Whilst both HSP20-3 and HSP20-6 formed particles that were variable in size and larger than the particles formed by CRYAB, only HSP20-3 formed filament-like structures. The particles and filament-like structures formed by HSP20-3 appear inter-related as the filament-like structures often had particles located at their ends. Sequence analyses identified two unique features; an insertion in the middle region of the N-terminal domain (NTD) and preceding the critical-sequence identified in CRYAB, as well as a repeated QNTN-motif located in the C-terminal domain of HSP20-3. The NTD insertion is expected to affect protein-protein interactions and subunit oligomerisation. Removal of the repeated QNTN-motif abolished HSP20-3 chaperone activity and also affected the assembly of the filament-like structures. We discuss the potential contribution of HSP20-3 to protein condensate formation.
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Affiliation(s)
- Mohammad Al-Ansari
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK; Department of Biochemistry, Health Sciences Centre, Kuwait University, Kuwait
| | - Taylor Fitzsimons
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK
| | - Wenbin Wei
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK.
| | - Martin W Goldberg
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK
| | - Takekazu Kunieda
- Department of Biological Sciences, The University of Tokyo, Japan
| | - Roy A Quinlan
- Department of Biosciences, Upper Mountjoy Science Site, University of Durham, Durham DH1 3LE, UK; Department of Biological Structure, University of Washington, Seattle, WA 98195, USA.
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Hvidepil LKB, Møbjerg N. New insights into osmobiosis and chemobiosis in tardigrades. Front Physiol 2023; 14:1274522. [PMID: 37929212 PMCID: PMC10620314 DOI: 10.3389/fphys.2023.1274522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 10/02/2023] [Indexed: 11/07/2023] Open
Abstract
Tardigrades are renowned for their ability to enter the extremotolerant state of latent life known as cryptobiosis. While it is widely accepted that cryptobiosis can be induced by freezing (cryobiosis) and by desiccation (anhydrobiosis), the latter involving formation of a so-called tun, the exact mechanisms underlying the state-as well as the significance of other cryptobiosis inducing factors-remain ambiguous. Here, we focus on osmotic and chemical stress tolerance in the marine tidal tardigrade Echiniscoides sigismundi. We show that E. sigismundi enters the tun state following exposure to saturated seawater and upon exposure to locality seawater containing the mitochondrial uncoupler DNP. The latter experiments provide evidence of osmobiosis and chemobiosis, i.e., cryptobiosis induced by high levels of osmolytes and toxicants, respectively. A small decrease in survival was observed following simultaneous exposure to DNP and saturated seawater indicating that the tardigrades may not be entirely ametabolic while in the osmobiotic tun. The tardigrades easily handle exposure to ultrapure water, but hypo-osmotic shock impairs tun formation and when exposed to ultrapure water the tardigrades do not tolerate DNP, indicating that tolerance towards dilute solutions involves energy-consuming processes. We discuss our data in relation to earlier and more contemporary studies on cryptobiosis and we argue that osmobiosis should be defined as a state of cryptobiosis induced by high external osmotic pressure. Our investigation supports the hypothesis that the mechanisms underlying osmobiosis and anhydrobiosis are overlapping and that osmobiosis likely represents the evolutionary forerunner of cryptobiosis forms that involve body water deprivation.
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Affiliation(s)
| | - Nadja Møbjerg
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
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6
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Giovannini I, Manfrin C, Greco S, Vincenzi J, Altiero T, Guidetti R, Giulianini P, Rebecchi L. Increasing temperature-driven changes in life history traits and gene expression of an Antarctic tardigrade species. Front Physiol 2023; 14:1258932. [PMID: 37766751 PMCID: PMC10520964 DOI: 10.3389/fphys.2023.1258932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 08/23/2023] [Indexed: 09/29/2023] Open
Abstract
The Antarctic region has been experiencing some of the planet's strongest climatic changes, including an expected increase of the land temperature. The potential effects of this warming trend will lead ecosystems to a risk of losing biodiversity. Antarctic mosses and lichens host different microbial groups, micro-arthropods and meiofaunal organisms (e.g., tardigrades, rotifers). The eutardigrade Acutuncus antarcticus is considered a model animal to study the effect of increasing temperature due to global warming on Antarctic terrestrial communities. In this study, life history traits and fitness of this species are analyzed by rearing specimens at two different and increasing temperatures (5°C vs. 15°C). Moreover, the first transcriptome analysis on A. antarcticus is performed, exposing adult animals to a gradual increase of temperature (5°C, 10°C, 15°C, and 20°C) to find differentially expressed genes under short- (1 day) and long-term (15 days) heat stress. Acutuncus antarcticus specimens reared at 5°C live longer (maximum life span: 686 days), reach sexual maturity later, lay more eggs (which hatch in longer time and in lower percentage) compared with animals reared at 15°C. The fitness decreases in animals belonging to the second generation at both rearing temperatures. The short-term heat exposure leads to significant changes at transcriptomic level, with 67 differentially expressed genes. Of these, 23 upregulated genes suggest alterations of mitochondrial activity and oxido-reductive processes, and two intrinsically disordered protein genes confirm their role to cope with heat stress. The long-term exposure induces alterations limited to 14 genes, and only one annotated gene is upregulated in response to both heat stresses. The decline in transcriptomic response after a long-term exposure indicates that the changes observed in the short-term are likely due to an acclimation response. Therefore, A. antarcticus could be able to cope with increasing temperature over time, including the future conditions imposed by global climate change.
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Affiliation(s)
- Ilaria Giovannini
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
| | - Chiara Manfrin
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Samuele Greco
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Joel Vincenzi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Tiziana Altiero
- NBFC, National Biodiversity Future Center, Palermo, Italy
- Department of Education and Humanities, University of Modena and Reggio Emilia, Reggio Emilia, Italy
| | - Roberto Guidetti
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
| | - Piero Giulianini
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Lorena Rebecchi
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
- NBFC, National Biodiversity Future Center, Palermo, Italy
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7
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Escarcega RD, Patil AA, Meyer MD, Moruno-Manchon JF, Silvagnoli AD, McCullough LD, Tsvetkov AS. The Tardigrade damage suppressor protein Dsup promotes DNA damage in neurons. Mol Cell Neurosci 2023; 125:103826. [PMID: 36858083 PMCID: PMC10247392 DOI: 10.1016/j.mcn.2023.103826] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 02/18/2023] [Accepted: 02/22/2023] [Indexed: 03/02/2023] Open
Abstract
Tardigrades are microscopic invertebrates, which are capable of withstanding extreme environmental conditions, including high levels of radiation. A Tardigrade protein, Dsup (Damage Suppressor), protects the Tardigrade's DNA during harsh environmental stress and X-rays. When expressed in cancer cells, Dsup protects DNA from single- and double-strand breaks (DSBs) induced by radiation, increases survival of irradiated cells, and protects DNA from reactive oxygen species. These unusual properties of Dsup suggested that understanding how the protein functions may help in the design of small molecules that could protect humans during radiotherapy or space travel. Here, we investigated if Dsup is protective in cortical neurons cultured from rat embryos. We discovered that, in cortical neurons, the codon-optimized Dsup localizes to the nucleus and, surprisingly, promotes neurotoxicity, leading to neurodegeneration. Unexpectedly, we found that Dsup expression results in the formation of DNA DSBs in cultured neurons. With electron microscopy, we discovered that Dsup promotes chromatin condensation. Unlike Dsup's protective properties in cancerous cells, in neurons, Dsup promotes neurotoxicity, induces DNA damage, and rearranges chromatin. Neurons are sensitive to Dsup, and Dsup is a doubtful surrogate for DNA protection in neuronal cells.
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Affiliation(s)
- Rocio Diaz Escarcega
- Department of Neurology, The University of Texas McGovern Medical School at Houston, TX 77030, United States of America
| | - Abhijeet A Patil
- Department of Neurology, The University of Texas McGovern Medical School at Houston, TX 77030, United States of America
| | - Matthew D Meyer
- Shared Equipment Authority, Rice University, Houston, TX 77005, United States of America
| | - Jose F Moruno-Manchon
- Department of Neurology, The University of Texas McGovern Medical School at Houston, TX 77030, United States of America
| | - Alexander D Silvagnoli
- Department of Neurology, The University of Texas McGovern Medical School at Houston, TX 77030, United States of America
| | - Louise D McCullough
- Department of Neurology, The University of Texas McGovern Medical School at Houston, TX 77030, United States of America; The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, United States of America
| | - Andrey S Tsvetkov
- Department of Neurology, The University of Texas McGovern Medical School at Houston, TX 77030, United States of America; The University of Texas Graduate School of Biomedical Sciences, Houston, TX 77030, United States of America; UTHealth Consortium on Aging, The University of Texas McGovern Medical School, Houston, TX 77030, United States of America.
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8
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Metivier JC, Chain FJJ. Diversity in Expression Biases of Lineage-Specific Genes During Development and Anhydrobiosis Among Tardigrade Species. Evol Bioinform Online 2022; 18:11769343221140277. [PMID: 36578471 PMCID: PMC9791283 DOI: 10.1177/11769343221140277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/27/2022] [Indexed: 12/24/2022] Open
Abstract
Lineage-specific genes can contribute to the emergence and evolution of novel traits and adaptations. Tardigrades are animals that have adapted to tolerate extreme conditions by undergoing a form of cryptobiosis called anhydrobiosis, a physical transformation to an inactive desiccated state. While studies to understand the genetics underlying the interspecies diversity in anhydrobiotic transitions have identified tardigrade-specific genes and family expansions involved in this process, the contributions of species-specific genes to the variation in tardigrade development and cryptobiosis are less clear. We used previously published transcriptomes throughout development and anhydrobiosis (5 embryonic stages, 7 juvenile stages, active adults, and tun adults) to assess the transcriptional biases of different classes of genes between 2 tardigrade species, Hypsibius exemplaris and Ramazzottius varieornatus. We also used the transcriptomes of 2 other tardigrades, Echiniscoides sigismundi and Richtersius coronifer, and data from 3 non-tardigrade species (Adenita vaga, Drosophila melanogaster, and Caenorhabditis elegans) to help identify lineage-specific genes. We found that lineage-specific genes have generally low and narrow expression but are enriched among biased genes in different stages of development depending on the species. Biased genes tend to be specific to early and late development, but there is little overlap in functional enrichment of biased genes between species. Gene expansions in the 2 tardigrades also involve families with different functions despite homologous genes being expressed during anhydrobiosis in both species. Our results demonstrate the interspecific variation in transcriptional contributions and biases of lineage-specific genes during development and anhydrobiosis in 2 tardigrades.
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Affiliation(s)
| | - Frédéric J J Chain
- Frédéric J J Chain, Department of Biological Sciences, University of Massachusetts Lowell, One University Ave, Lowell, MA 01854, USA.
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Møbjerg A, Kodama M, Ramos-Madrigal J, Neves RC, Jørgensen A, Schiøtt M, Gilbert MTP, Møbjerg N. Extreme freeze-tolerance in cryophilic tardigrades relies on controlled ice formation but does not involve significant change in transcription. Comp Biochem Physiol A Mol Integr Physiol 2022; 271:111245. [PMID: 35640792 DOI: 10.1016/j.cbpa.2022.111245] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/30/2022]
Abstract
Subzero temperatures are among the most significant factors defining the distribution of organisms, yet, certain taxa have evolved to overcome this barrier. The microscopic tardigrades are among the most freeze-tolerant animals, with selected species reported to survive milli-Kelvin temperatures. Here, we estimate survival of fully hydrated eutardigrades of the species Ramazzottius varieornatus following exposures to -20 °C and -80 °C as well as -196 °C with or without initial cooling to -80 °C. The tardigrades easily survive these temperatures, yet with a significant decrease in viability following rapid cooling by direct exposure to -196 °C. Hence, post-freeze recovery of R. varieornatus seems to rely on cooling rate and thus controlled ice formation. Cryophilic organisms are renowned for having cold-active enzymes that secure appropriate reaction rates at low temperatures. Hence, extreme freeze-tolerance in R. varieornatus could potentially involve syntheses of cryoprotectants and de novo transcription. We therefore generated a reference transcriptome for this cryophilic R. varieornatus population and explored for differential gene expression patterns following cooling to -80 °C as compared to active 5 °C controls. Specifically, we tested for fast transcription potentially occurring within 25 min of cooling from room temperature to a supercooling point of ca. -20 °C, at which the tardigrades presumably freeze and enter into the ametabolic state of cryobiosis. Our analyses revealed no evidence for differential gene expression. We, therefore, conclude that extreme freeze-tolerance in R. varieornatus relies on controlled extracellular freezing with any freeze-tolerance related genes being constitutively expressed.
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Affiliation(s)
- Ask Møbjerg
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, Copenhagen, Denmark. https://twitter.com/askmobjerg
| | - Miyako Kodama
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - Jazmín Ramos-Madrigal
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | | | - Aslak Jørgensen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Morten Schiøtt
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - M Thomas P Gilbert
- Center for Evolutionary Hologenomics, The Globe Institute, University of Copenhagen, Copenhagen, Denmark; University Museum, NTNU, Trondheim, Norway
| | - Nadja Møbjerg
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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