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Stec D, Krzywański Ł, Arakawa K, Michalczyk Ł. A new redescription of Richtersius coronifer, supported by transcriptome, provides resources for describing concealed species diversity within the monotypic genus Richtersius (Eutardigrada). ZOOLOGICAL LETTERS 2020; 6:2. [PMID: 32047649 PMCID: PMC7003491 DOI: 10.1186/s40851-020-0154-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/06/2020] [Indexed: 05/08/2023]
Abstract
Richtersius coronifer, the nominal species for the family Richtersiidae and a popular laboratory model, exemplifies a common problem in modern tardigrade taxonomy. Despite undeniable progress in the field, many old and incomplete descriptions of taxa hinder both species delimitation and the estimation of species diversity and distribution. Although for over a century this species has been recorded throughout the world, recent research indicates that records to date are likely to represent a species complex rather than a single cosmopolitan species. However, in order to recognise and name species diversity within the complex, an integrative redescription of the nominal species is first needed. Here, we describe an R. coronifer population collected from Spitsbergen, i.e., one of the two localities mentioned in the original description, with detailed morphological and morphometric data associated with standard DNA sequences of four standard genetic markers (18S rRNA, 28S rRNA, ITS-2, and COI) and supported by transcriptome sequencing. We propose replacement of the neotype designated in 1981 by Maucci and Ramazzotti, as it is impossible to verify whether the existing neotype is conspecific with specimens studied by Richters in 1903 and 1904. Finally, using newly obtained cytochrome c oxidase subunit I (COI) sequences of populations from Spitsbergen, Italy, Poland, and Greece together with sequences deposited in GenBank (China, Greenland, Italy, Mongolia), we performed genetic species delimitation, which indicated seven distinct potential species within the genus Richtersius, in addition to the nominal taxon. This study marks a starting point for further research on the taxonomy of and species diversity within the genus. Moreover, this work has the potential to be the first tardigrade redescription to provide both genetic barcodes and a transcriptome of the species in question.
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Affiliation(s)
- Daniel Stec
- Department of Entomology, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland
| | - Łukasz Krzywański
- Department of Entomology, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland
| | - Kazuharu Arakawa
- Institute for Advanced Biosciences, Keio University, Mizukami 246-2, Kakuganji, Tsuruoka, Yamagata, Japan
| | - Łukasz Michalczyk
- Department of Entomology, Institute of Zoology and Biomedical Research, Jagiellonian University, Gronostajowa 9, 30-387 Kraków, Poland
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Khudyakov AN, Kuleshova LG, Zaitseva OO, Sergushkina MI, Vetoshkin KA, Polezhaeva TV. Effect of Pectins on Water Crystallization Pattern and Integrity of Cells During Freezing. Biopreserv Biobank 2019; 17:52-57. [DOI: 10.1089/bio.2018.0066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Affiliation(s)
- Andrey Nikolayevich Khudyakov
- Laboratory of Cryophysiology of Blood, Institute of Physiology, Komi Scientific Center of the Russian Academy of Sciences, Komi Republic, Syktyvkar, Russian Federation
| | - Larisa Georgievna Kuleshova
- Institute for Problems of Cryobiology and Cryomedicine, National Academy of Sciences of Ukraine, Kharkiv, Ukraine
| | - Oksana Olegovna Zaitseva
- Laboratory of Cryophysiology of Blood, Institute of Physiology, Komi Scientific Center of the Russian Academy of Sciences, Komi Republic, Syktyvkar, Russian Federation
| | - Marta Igorevna Sergushkina
- Laboratory of Cryophysiology of Blood, Institute of Physiology, Komi Scientific Center of the Russian Academy of Sciences, Komi Republic, Syktyvkar, Russian Federation
| | | | - Tatyana Vitalyevna Polezhaeva
- Laboratory of Cryophysiology of Blood, Institute of Physiology, Komi Scientific Center of the Russian Academy of Sciences, Komi Republic, Syktyvkar, Russian Federation
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Møbjerg N, Halberg KA, Jørgensen A, Persson D, Bjørn M, Ramløv H, Kristensen RM. Survival in extreme environments - on the current knowledge of adaptations in tardigrades. Acta Physiol (Oxf) 2011; 202:409-20. [PMID: 21251237 DOI: 10.1111/j.1748-1716.2011.02252.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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.
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Affiliation(s)
- N Møbjerg
- Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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Guidetti R, Altiero T, Rebecchi L. On dormancy strategies in tardigrades. JOURNAL OF INSECT PHYSIOLOGY 2011; 57:567-76. [PMID: 21402076 DOI: 10.1016/j.jinsphys.2011.03.003] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 03/02/2011] [Accepted: 03/03/2011] [Indexed: 05/19/2023]
Abstract
In this review we analyze the dormancy strategies of metazoans inhabiting "hostile to life" habitats, which have a strong impact on their ecology and in particular on the traits of their life history. Tardigrades are here considered a model animal, being aquatic organisms colonizing terrestrial habitats. Tardigrades evolved a large variety of dormant stages that can be ascribed to diapause (encystment, cyclomorphosis, resting eggs) and cryptobiosis (anhydrobiosis, cryobiosis, anoxibiosis). In tardigrades, diapause and cryptobiosis can occur separately or simultaneously, consequently the adoption of one adaptive strategy is not necessarily an alternative to the adoption of the other. Encystment and cyclomorphosis are characterized by seasonal cyclic changes in morphology and physiology of the animals. They share several common features and their evolution is strictly linked to the molting process. A bet-hedging strategy with different patterns of egg hatching time has been observed in a tardigrade species. Four categories of eggs have been identified: subitaneous, delayed-hatching, abortive and diapause resting eggs, which needs a stimulus to hatch (rehydration after a period of desiccation). Cryptobiotic tardigrades are able to withstand desiccation (anhydrobiosis) and freezing (cryobiosis) at any stage of their life-cycle. This ability involves a complex array of factors working at molecular (bioprotectans), physiological and structural levels. Animal survival and the accumulation of molecular damage are related to the time spent in the cryptobiotic state, to the abiotic parameters during the cryptobiotic state, and to the conditions during initial and final phases of the process. Cryptobiosis evolved independently at least two times in tardigrades, in eutardigrades and in echiniscoids. Within each evolutionary line, the absence of cryptobiotic abilities is more related to selective pressures to local habitat adaptation than to phylogenetic relationships. The selective advantages of cryptobiosis (e.g. persistency in "hostile to life" habitats, reduction of competitors, parasites and predators, escaping in time from stressful conditions) could explain the high tardigrade species diversity and number of specimens found in habitats that dry out compared to freshwater habitats.
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Affiliation(s)
- Roberto Guidetti
- Department of Biology, University of Modena and Reggio Emilia, via Campi 213/D, 41125 Modena, Italy.
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Guidetti R, Altiero T, Bertolani R, Grazioso P, Rebecchi L. Survival of freezing by hydrated tardigrades inhabiting terrestrial and freshwater habitats. ZOOLOGY 2011; 114:123-8. [PMID: 21429723 DOI: 10.1016/j.zool.2010.11.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 10/07/2010] [Accepted: 11/02/2010] [Indexed: 10/18/2022]
Abstract
The seasonality and unpredictability of environmental conditions at high altitudes and latitudes govern the life cycle patterns of organisms, giving rise to stresses that cause 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.
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Affiliation(s)
- Roberto Guidetti
- Department of Biology, University of Modena and Reggio Emilia, Via Campi 213/D, 41125 Modena, Italy.
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Ice crystallization and freeze tolerance in embryonic stages of the tardigrade Milnesium tardigradum. Comp Biochem Physiol A Mol Integr Physiol 2010; 156:151-5. [DOI: 10.1016/j.cbpa.2010.01.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 01/19/2010] [Accepted: 01/23/2010] [Indexed: 11/17/2022]
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Schill RO, Mali B, Dandekar T, Schnölzer M, Reuter D, Frohme M. Molecular mechanisms of tolerance in tardigrades: New perspectives for preservation and stabilization of biological material. Biotechnol Adv 2009; 27:348-52. [DOI: 10.1016/j.biotechadv.2009.01.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Hengherr S, Worland MR, Reuner A, Brümmer F, Schill RO. Freeze tolerance, supercooling points and ice formation: comparative studies on the subzero temperature survival of limno-terrestrial tardigrades. J Exp Biol 2009; 212:802-7. [DOI: 10.1242/jeb.025973] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Many limno-terrestrial tardigrades live in unstable habitats where they experience extreme environmental conditions such as drought, heat and subzero temperatures. Although their stress tolerance is often related only to the anhydrobiotic state, tardigrades can also be exposed to great daily temperature fluctuations without dehydration. Survival of subzero temperatures in an active state requires either the ability to tolerate the freezing of body water or mechanisms to decrease the freezing point. Considering freeze tolerance in tardigrades as a general feature, we studied the survival rate of nine tardigrade species originating from polar, temperate and tropical regions by cooling them at rates of 9, 7, 5, 3 and 1°C h–1 down to –30°C then returning them to room temperature at 10°C h–1. The resulting moderate survival after fast and slow cooling rates and low survival after intermediate cooling rates may indicate the influence of a physical effect during fast cooling and the possibility that they are able to synthesize cryoprotectants during slow cooling. Differential scanning calorimetry of starved, fed and cold acclimatized individuals showed no intraspecific significant differences in supercooling points and ice formation. Although this might suggest that metabolic and biochemical preparation are non-essential prior to subzero temperature exposure, the increased survival rate with slower cooling rates gives evidence that tardigrades still use some kind of mechanism to protect their cellular structure from freezing injury without influencing the freezing temperature. These results expand our current understanding of freeze tolerance in tardigrades and will lead to a better understanding of their ability to survive subzero temperature conditions.
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Affiliation(s)
- S. Hengherr
- Universität Stuttgart, Biological Institute, Department of Zoology,Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - M. R. Worland
- British Antarctic Survey, Natural Environment Research Council, High Cross,Madingley Road, Cambridge CB3 0ET, UK
| | - A. Reuner
- Universität Stuttgart, Biological Institute, Department of Zoology,Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - F. Brümmer
- Universität Stuttgart, Biological Institute, Department of Zoology,Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - R. O. Schill
- Universität Stuttgart, Biological Institute, Department of Zoology,Pfaffenwaldring 57, 70569 Stuttgart, Germany
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Lundheim R. Physiological and ecological significance of biological ice nucleators. Philos Trans R Soc Lond B Biol Sci 2002; 357:937-43. [PMID: 12171657 PMCID: PMC1693005 DOI: 10.1098/rstb.2002.1082] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
When a pure water sample is cooled it can remain in the liquid state at temperatures well below its melting point (0 degrees C). The initiation of the transition from the liquid state to ice is called nucleation. Substances that facilitate this transition so that it takes place at a relatively high sub-zero temperature are called ice nucleators. Many living organisms produce ice nucleators. In some cases, plausible reasons for their production have been suggested. In bacteria, they could induce frost damage to their hosts, giving the bacteria access to nutrients. In freeze-tolerant animals, it has been suggested that ice nucleators help to control the ice formation so that it is tolerable to the animal. Such ice nucleators can be called adaptive ice nucleators. There are, however, also examples of ice nucleators in living organisms where the adaptive value is difficult to understand. These ice nucleators might be structures with functions other than facilitating ice formation. These structures might be called incidental ice nucleators.
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Affiliation(s)
- Rolv Lundheim
- Allforsk Biology, Queen Maud College, Thonning Owesensgt 18, 7044 Trondheim, Norway.
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Wright JC. Cryptobiosis 300 Years on from van Leuwenhoek: What Have We Learned about Tardigrades? ZOOL ANZ 2001. [DOI: 10.1078/0044-5231-00068] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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McInnes S. Zoogeographic distribution of terrestrial/freshwater tardigrades from current literature. J NAT HIST 1994. [DOI: 10.1080/00222939400770131] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Ramløv H, Westh P. Survival of the cryptobiotic eutardigrade Adorybiotus coronifer during cooling to −196 °C: Effect of cooling rate, trehalose level, and short-term acclimation. Cryobiology 1992. [DOI: 10.1016/0011-2240(92)90012-q] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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