High‐Temperature Tolerance in Anhydrobiotic Tardigrades Is Limited by Glass Transition

Abstract

Survival in microhabitats that experience extreme fluctuations in water availability and temperature requires special adaptations. To withstand such environmental conditions, tardigrades, as well as some nematodes and rotifers, enter a completely desiccated state known as anhydrobiosis. We examined the effects of high temperatures on fully desiccated (anhydrobiotic) tardigrades. Nine species from the classes Heterotardigrada and Eutardigrada were exposed to temperatures of up to 110 degrees C for 1 h. Exposure to temperatures of up to 80 degrees C resulted in a moderate decrease in survival. Exposure to temperatures above this resulted in a sharp decrease in survival, with no animals of the families Macrobiotidae and Echiniscidae surviving 100 degrees C. However, Milnesium tardigradum (Milnesidae) showed survival of >90% after exposure to 100 degrees C; temperatures above this resulted in a steep decrease in survival. Vitrification is assumed to play a major role in the survival of anhydrobiotic organisms during exposure to extreme temperatures, and consequently, the glass-transition temperature (T(g)) is critical to high-temperature tolerance. In this study, we provide the first evidence of the presence of a glass transition during heating in an anhydrobiotic tardigrade through the use of differential scanning calorimetry.

The metameric pattern of Hypsibius dujardini(Eutardigrada) and its relationship to that of other panarthropods

“…Fixation was followed by four 15 minute and one overnight wash in PB-Triton with 0.1% NaN 3 . Specimens were then incubated at room temperature for 27 hrs in a 1:40 dilution of phalloidin in PB-Triton with 0.1% NaN 3 . Following phalloidin incubation, specimens were rinsed three times for 5 minutes in PB-Triton.…”

“…The taxon Tardigrada is composed of microscopic invertebrates known for their remarkable ability to survive hostile environments, including extremes in temperature, pressure, salinity, radiation, and even the vacuum of outer space [1][2][3][4][5][6][7][8]. Tardigrada is an ancient lineage, with a fossil record extending back to the Cambrian period [9].…”

Hyperprolinemic larvae of the drosophilid fly, Chymomyza costata , survive cryopreservation in liquid nitrogen

“…it prevents lethal formation of intracellular ice crystals and provides molecular stability to macromolecules and cell structures. Recently, it was suggested that vitrification is an essential part of the survival strategy in anhydrobiotic invertebrates (30,31) and deeply supercooled arctic beetles (32).…”

Element analysis of the eutardigrades Richtersius coronifer and Milnesium cf. asiaticum using Particle Induced X-ray Emission (PIXE)

“…asiaticum, but another species (reported as Milnesium tardigradum Doyère 1840 but probably also M. asiaticum or M. cf. asiaticum) has been reported to be more tolerant than R. coronifer to ultraviolet radiation, freezing, and high temperature Westh, 1992, 2001;Jöns-son et al, 2008;Hengherr et al, 2009aHengherr et al, , 2009b. Also differences in biochemistry connected with desiccation have been documented in these two species (Westh and Ramløv, 1991;Hengherr et al, 2008;Jönsson and Persson, 2010).…”