Environmental Adaptations: Desiccation Tolerance

Schill, Ralph O.; Hengherr, Steffen

doi:10.1007/978-3-319-95702-9_10

Cited by 45 publications

(59 citation statements)

References 131 publications

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“…Since tardigrades on glaciers inhabit permanently aquatic/wet habitats, we can assume that they are freshwater species able to survive desiccation. Still, their recovery success is small in comparison with that of other limno-terrestrial water bears (Bertolani et al 2004;Schill and Hengherr 2019;Wełnicz et al 2011), and tardigrade species best adapted to desiccation are the ones inhabiting xeric environments, for example, lichens (Rebecchi et al 2006). Instead of typical anhydrobiosis, H. klebelsbergi most probably entered encystation, which is typical for freshwater species (Bertolani et al 2004).…”

Section: Discussionmentioning

confidence: 99%

Water bears dominated cryoconite hole ecosystems: densities, habitat preferences and physiological adaptations of Tardigrada on an alpine glacier

et al. 2019

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We investigated the Forni Glacier and the surrounding area in the Alps in terms of habitat preferences, densities, dispersal and desiccation tolerance of glacier tardigrades, which are one of the most common faunal representatives and top consumers in supraglacial ecosystems. To do so, we sampled supraglacial environments (cryoconite holes, debris from ice surface, dirt cones and moraine, mosses from supraglacial stones) and non-glacial habitats (mosses, freshwater sediments and algae), and we installed air traps on the glacier and the nearby area. We found that cryoconite holes on the Forni Glacier are exclusively dominated by one metazoan group of tardigrades, representing one species, Hypsibius klebelsbergi (identified by morphological and molecular approaches). Tardigrades were found in 100% of cryoconite holes and wet supraglacial sediment samples and reached up to 172 ind./ml. Additionally, we found glacier tardigrades in debris from dirt cones and sparsely in supraglacial mosses. Glacier tardigrades were absent from freshwater and terrestrial samples collected from non-glacial habitats. Despite the fact that H. klebelsbergi is a typical aquatic species, we showed it withstands desiccation in sediments, but in low temperatures only. Treatments conducted in higher temperatures and water only showed low or no recovery. We suspect successful dispersal with wind might have taken place only when tardigrades desiccated in sediments and were passively transported by cold wind. Limited ability to withstand high temperatures and desiccation may be potential barriers preventing glacier tardigrades inhabiting new, even apparently suitable high mountain water bodies like temporary rock pools.

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Section: Discussionmentioning

confidence: 99%

Water bears dominated cryoconite hole ecosystems: densities, habitat preferences and physiological adaptations of Tardigrada on an alpine glacier

et al. 2019

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“…Terrestrial tardigrades require to be surrounded by a thin film of water to maintain skeleton functions and oxygen uptake through cuticle. In the absence of water, tardigrades enter a dehydrated state called anhydrobiosis in which they are able to survive in nearly complete desiccation for up to 10 years [4][5][6] .…”

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confidence: 99%

A computational structural study on the DNA-protecting role of the tardigrade-unique Dsup protein

Mínguez-Toral

Cuevas-Zuviría

Garrido‐Arandia

et al. 2020

Sci Rep

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the remarkable ability of tardigrades to withstand a wide range of physical and chemical extremes has attracted a considerable interest in these small invertebrates, with a particular focus on the protective roles of proteins expressed during such conditions. the discovery that a tardigrade-unique protein named Dsup (damage suppressor) protects DnA from damage produced by radiation and radicals, has raised expectations concerning its potential applications in biotechnology and medicine. We present in this paper what might be dubbed a "computational experiment" on the Dsup-DnA system. By means of molecular modelling, calculations of electrostatic potentials and electric fields, and all-atom molecular dynamics simulations, we obtained a dynamic picture of the Dsup-DnA interaction. our results suggest that the protein is intrinsically disordered, which enables Dsup to adjust its structure to fit DNA shape. Strong electrostatic attractions and high protein flexibility drive the formation of a molecular aggregate in which Dsup shields DnA. While the precise mechanism of DnA protection conferred by Dsup remains to be elucidated, our study provides some molecular clues of their association that could be of interest for further investigation in this line.

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“…Different strategies of cryptobiosis have been described based on the environmental cues they are induced by: anhydrobiosis (desiccation), anoxybiosis (oxygen depletion), chemobiosis (high toxicant concentrations), cryobiosis (extremely low temperatures) and osmobiosis (high solute concentration) [ 2 – 4 ]. Anhydrobiosis – the best-studied form of cryptobiosis – refers to the ability to survive evaporative water loss [ 5 – 8 ]. In order to endure desiccation, tardigrades form a quiescent, barrel-shaped “tun” contracting the body longitudinally and retracting their head and legs [ 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…Tardigrades likely express an assortment of bioprotectants that protect cell membranes, DNA and proteins against damage, while the water evaporates from their bodies and desiccation ensues. Suggested bioprotectants include trehalose that can replace water during dehydration and stabilize cellular structure through vitrification [ 8 , 12 , 13 ]. Other proposed molecular adaptations include heat shock proteins (HSPs) and late embryogenesis abundant (LEA) proteins that act as molecular shields or chaperones and/or participate in the repair process after desiccation [ 14 , 15 ], as well as the recently discovered “tardigrade-unique proteins” [ 16 , 17 ].…”

Section: Introductionmentioning

confidence: 99%

New insights into the limited thermotolerance of anhydrobiotic tardigrades

Neves

Stuart

Møbjerg

2020

Communicative & Integrative Biology

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The recent discovery of an upper limit in the tolerance of an extremotolerant tardigrade to high temperatures is astounding. Although these microinvertebrates are able to endure severe environmental conditions, including desiccation, freezing and high levels of radiation, high temperatures seem to be an Achilles' heel for active tardigrades. Moreover, exposure-time appears to be a limiting factor for the heat stress tolerance of the otherwise highly resilient desiccated (anhydrobiotic) tardigrades. Indeed, the survival rate of desiccated tardigrades exposed to high temperatures for 24 hours is significantly lower than for exposures of only 1 hour. Here, we investigate the effect of 1 week of high temperature exposures on desiccated tardigrades with the aim of elucidating whether exposure-times longer than 24 hours decrease survival even further. From our analyses we estimate a significant decrease in the 50% mortality temperature from 63ºC to 56ºC for Ramazzottius varieornatus exposed to high temperatures in the desiccated tun state for 24 hours and 1 week, respectively. This negative correlation between exposure-time and tolerance to high temperatures probably results from the interference of intracellular temperature with the homeostasis of macromolecules. We hypothesize that high temperatures denature molecules that play a vital role in sustaining and protecting the anhydrobiotic state.

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Environmental Adaptations: Desiccation Tolerance

Cited by 45 publications

References 131 publications

Water bears dominated cryoconite hole ecosystems: densities, habitat preferences and physiological adaptations of Tardigrada on an alpine glacier

Water bears dominated cryoconite hole ecosystems: densities, habitat preferences and physiological adaptations of Tardigrada on an alpine glacier

A computational structural study on the DNA-protecting role of the tardigrade-unique Dsup protein

New insights into the limited thermotolerance of anhydrobiotic tardigrades

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