Osmotic stress tolerance in semi-terrestrial tardigrades

Heidemann, Nanna W. T.; Smith, Daniel; Hygum, Thomas L.; Stapane, Lilian; Clausen, Lykke K. B.; Jørgensen, Aslak; Hélix-Nielsen, Claus; Møbjerg, Nadja

doi:10.1111/zoj.12502

Cited by 27 publications

(24 citation statements)

References 27 publications

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“…A similar pattern revealing a somewhat lower tolerance in Echiniscoides as compared to semi-terrestrial tardigrades was observed in a study on tolerance to gamma radiation 35 . The latter may simply reflect a variation in the tolerance level of specific tardigrade species, but, importantly, could also support the argument that electrolyte solutions have a detrimental effect on the ability to recover from extreme stress, as previously reported for semi-terrestrial species 36 .…”

Section: Discussionsupporting

confidence: 79%

Modelling extreme desiccation tolerance in a marine tardigrade

Sørensen-Hygum

Stuart

Jørgensen

et al. 2018

Sci Rep

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It has recently been argued that the enigmatic tardigrades (water bears) will endure until the sun dies, surviving any astrophysical calamities in Earth’s oceans. Yet, our knowledge of stress tolerance among marine tardigrade species is very limited and most investigations revolve around species living in moist habitats on land. Here, we investigate desiccation tolerance in the cosmopolitan marine tidal tardigrade, Echiniscoides sigismundi, providing the first thorough analysis on recovery upon desiccation from seawater. We test the influence on survival of desiccation surface, time spent desiccated (up to 1 year) and initial water volume. We propose analysis methods for survival estimates, which can be used as a future platform for evaluating and analysing recovery rates in organisms subjected to extreme stress. Our data reveal that marine tidal tardigrades tolerate extremely rapid and extended periods of desiccation from seawater supporting the argument that these animals are among the toughest organisms on Earth.

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Section: Discussionsupporting

confidence: 79%

Modelling extreme desiccation tolerance in a marine tardigrade

Sørensen-Hygum

Stuart

Jørgensen

et al. 2018

Sci Rep

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“…20 tardigrades were kept refrigerated (5 °C) for 24 hours as controls. A moss leaf was deliberately added in each Eppendorf tube, in order for the tardigrades to have something to hold on to and not spend too much energy searching for substrate 77,78 . We further tested the tolerance of the active state following a brief high temperature acclimation period.…”

Section: Discussionmentioning

confidence: 99%

Thermotolerance experiments on active and desiccated states of Ramazzottius varieornatus emphasize that tardigrades are sensitive to high temperatures

Neves

Hvidepil

Sørensen-Hygum

et al. 2020

Sci Rep

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Global warming is already having harmful effects on habitats worldwide and it is therefore important to gain an understanding of how rising temperatures may affect extant animals. Here, we investigate the tolerance to high temperatures of Ramazzottius varieornatus, a tardigrade frequently found in transient freshwater habitats. Using logistic modelling on activity we evaluate the effect of 24 hour temperature exposures on active tardigrades, with or without a short acclimation period, compared to exposures of desiccated tardigrades. We estimate that the 50% mortality temperature for non-acclimated active tardigrades is 37.1 °C, with a small but significant increase to 37.6 °C following acclimation. Desiccated specimens tolerate much higher temperatures, with an estimated 50% mortality temperature of 82.7 °C following 1 hour exposures, but with a significant decrease to 63.1 °C following 24 hour exposures. our results show that metabolically active tardigrades are vulnerable to high temperatures, yet acclimatization could provide a tolerance increase. Desiccated specimens show a much higher resilience-exposure-time is, however, a limiting factor giving tardigrades a restricted window of high temperature tolerance. tardigrades are renowned for their ability to tolerate extreme conditions, but their endurance towards high temperatures clearly has an upper limit-high temperatures thus seem to be their Achilles heel.

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“…23]. The underlying mechanisms could, however, differ between the different types of adaptations as well as between tardigrade lineages [24], underlining the importance of investigations into more heterotardigrade species.…”

Section: Discussionmentioning

confidence: 99%

Tolerance to Gamma Radiation in the Marine Heterotardigrade, Echiniscoides sigismundi

et al. 2016

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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.

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Osmotic stress tolerance in semi-terrestrial tardigrades

Cited by 27 publications

References 27 publications

Modelling extreme desiccation tolerance in a marine tardigrade

Modelling extreme desiccation tolerance in a marine tardigrade

Thermotolerance experiments on active and desiccated states of Ramazzottius varieornatus emphasize that tardigrades are sensitive to high temperatures

Tolerance to Gamma Radiation in the Marine Heterotardigrade, Echiniscoides sigismundi

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