Survival in extreme environments – on the current knowledge of adaptations in tardigrades

  title={Survival in extreme environments – on the current knowledge of adaptations in tardigrades},
  author={Nadja M{\o}bjerg and Kenneth Agerlin Halberg and Aslak J{\o}rgensen and Dennis K. Persson and M Jenssen Bjorn and Hans Raml{\o}v and Reinhardt M{\o}bjerg Kristensen},
  journal={Acta Physiologica},
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… 

Differential mechanisms of tolerance to extreme environmental conditions in tardigrades

This work annotated the genomes of both tardigrades using a guided approach and found specific amplifications of several genes, including MRE11 and XPC, and numerous missense variants exclusive of R. varieornatus in CHEK1, POLK, UNG and TERT, all of them involved in important pathways for DNA repair and telomere maintenance.

Extreme-tolerance mechanisms in meiofaunal organisms: a case study with tardigrades, rotifers and nematodes

This review will analyse the dormancy strategies in tardigrades, rotifers and nematodes with emphasis on mechanisms of extreme stress tolerance to identify convergent and unique strategies occurring in these distinct groups.

New insights into survival strategies of tardigrades.

  • N. MøbjergR. Neves
  • Biology
    Comparative biochemistry and physiology. Part A, Molecular & integrative physiology
  • 2020

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

Tardigrades seem to have a well-developed battery of cuproproteins involved in copper homeostasis, providing basis for active copper sequestering and excretion and supporting the hypothesis that copper inhibits sodium turnover as demonstrated for other aquatic organisms.

Respiration Measurements of Individual Tardigrades of the Species Richtersius cf coronifer as a Function of Temperature and Salinity and Termination of Anhydrobiosis.

First measurements of mass-specific respiration rates of individual tardigrades of the species Richtersius cf coronifer during termination of anhydrobiosis are reported as well as measurements of the impact of temperature and salinity on oxygen uptake rates.

Ecology and thermal tolerance of the marine tardigrade Halobiotus crispae (Eutardigrada: Isohypsibiidae)

The thermal tolerance data reveal that the entry into the pseudosimplex 1 stage represents an adaptive strategy that enables the survival of the Vellerup Vig population during periods of heat stress, and temperature is an important factor in limiting the geographic distribution of H. crispae.

Tun formation is not a prerequisite for desiccation tolerance in the marine tidal tardigrade Echiniscoides sigismundi

It is suggested that tun formation may have evolved as a response to elevated external pressure rather than desiccation per se, and that E. sigismundi tolerates being dehydrated from ultrapurified water, revealing an exceptional and unparalleled resilience towards losing structural integrity.

Resistance to Extreme Stresses by a Newly Discovered Japanese Tardigrade Species, Macrobiotus kyoukenus (Eutardigrada, Macrobiotidae)

Tardigrades are small micrometazoans able to resist several environmental stresses in any stage of their life cycle and an integrated analysis of tardigrade specimens collected in Tsukuba (Japan) revealed a peculiar morphology and a new sensory field in the cloaca that could become a new emerging model for stress resistance studies.

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

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 and revealing that maintaining structural integrity is essential for resumption of life following rehydration.



Cyclomorphosis in Tardigrada: adaptation to environmental constraints

Investigating mechanisms of survival and physiological adaptations associated with sub-zero temperatures and severe osmotic stress in two commonly found cyclomorphic stages of the marine eutardigrade Halobiotus crispae shows that only animals in the so-called pseudosimplex 1 stage are freeze tolerant.

Experiences with dormancy in tardigrades

The analysis of life history traits of a laboratory reared strain of a soil tardigrade revealed a particular hatching phenology that involved the production of both subitaneous and resting eggs, and the evolutionary meaning of dormancy in tardsigrades is discussed.

Diapause in tardigrades: a study of factors involved in encystment

Evidence is obtained that A. volubilis is able to perform both diapause and cryptobiosis, even overlapping the two phenomena, indicating an involvement of endogenous factors in tardigrade encystment.

Establishment of a rearing system of the extremotolerant tardigrade Ramazzottius varieornatus: a new model animal for astrobiology.

The successful rearing of the herbivorous tardigrade, Ramazzottius varieornatus, by supplying the green alga Chlorella vulgaris as food is reported, and it is reported that the reared individuals of this species had an anhydrobiotic capacity throughout their life cycle in egg, juvenile, and adult stages.

Extreme stress tolerance in tardigrades: surviving space conditions in low earth orbit

The primary focus was to assess the impact of cosmic radiation on the survival of the eutardigrade Richtersius coronifer and experiments testing extreme cold and vacuum tolerance in R. coronifer show that tardigrades inanhydrobiosis are unaffected by these conditions.

Anhydrobiotic Abilities of Tardigrades

In several desiccated species glass transition has been detected, which support the vitrification hypothesis, and heat shock proteins serve as molecular chaperones to preserve or restore the protein integrity and late embryogenesis abundant (LEA) proteins LEA proteins play an important role as well.

Anhydrobiosis: the extreme limit of desiccation tolerance

This review presents the response to desiccation from molecules to cells and organisms, the extraordinary resistance to chemical and physical extremes, the morphological, physiological, biochemical, and molecular constraints allowing organisms to enter and to survive anhydrobiosis, and the evolutionary meaning of life without water.

Trehalose and anhydrobiosis in tardigrades – evidence for divergence in responses to dehydration

The accumulation of trehalose is demonstrated in developing tardigrade embryos, which have been shown to have a high level of desiccation tolerance, and, for the first time, is shown in species of the order Parachela.

Trehalose in three species of desiccation tolerant tardigrades

The presence of the disaccharide trehalose was found in three desiccation tolerant tardigrades, with increased levels in dehydrated specimens of MacRobiotus islandicus, and possibly also in Macrobiotus krynauwi, both belonging to the family Macrobioticidae.

Radiation tolerance in the eutardigrade Richtersius coronifer

The study suggests that radiation tolerance in tardigrades is not due to biochemical protectants connected with the desiccated state, but may rely on efficient mechanisms of DNA repair, the nature of which is currently unknown.