University of Wyoming, Department of Molecular Biology, Laramie, WY 82071, USA.
University of Modena and Reggio Emilia, Department of Life Sciences, Modena 41125, Italy.
Biol Open. 2024 Oct 15;13(10). doi: 10.1242/bio.060485. Epub 2024 Sep 25.
Tardigrades are known for their ability to survive extreme conditions. Reports indicate that tardigrade thermal tolerance is enhanced in the desiccated state; however, these reports have almost always used a single tardigrade species and drying/heating methods vary between studies. Using six different species of tardigrades we confirm that desiccation enhances thermal tolerance in tardigrades. Furthermore, we show that differences in thermal tolerance exist between tardigrade species both when hydrated and desiccated. While Viridiscus viridianus survives the highest temperatures in the hydrated state of any species tested here, under hydrated conditions, the thermal tolerance of V. viridianus is restricted to an acute transient stress. Furthermore, unlike other stresses, such as desiccation, where mild initial exposure preconditions some species to survive subsequent harsher treatment, for V. viridianus exposure to mild thermal stress in the hydrated state does not confer protection to harsher heating. Our results suggest that while tardigrades have the capacity to tolerate mild thermal stress while hydrated, survival of high temperatures in a desiccated state is a by-product of tardigrades' ability to survive desiccation.
缓步动物以能够在极端条件下生存而闻名。有报道表明，在干燥状态下，缓步动物的耐热性增强；然而，这些报道几乎总是使用单一的缓步动物物种，并且干燥/加热方法在不同的研究中也有所不同。我们使用六种不同的缓步动物物种证实，干燥确实可以增强缓步动物的耐热性。此外，我们还表明，即使在水合状态和干燥状态下，缓步动物物种之间的耐热性也存在差异。虽然在测试的所有物种中，Viridiscus viridianus 在水合状态下能够承受最高的温度，但在水合条件下，Viridiscus viridianus 的耐热性仅限于急性短暂应激。此外，与其他应激（如干燥）不同，轻度初始暴露会使一些物种对随后更恶劣的处理产生适应，但对于 V. viridianus 来说，在水合状态下暴露于轻度热应激不会赋予其对更恶劣加热的保护作用。我们的研究结果表明，虽然缓步动物在水合状态下有能力耐受轻度热应激，但在干燥状态下耐受高温是缓步动物能够耐受干燥的副产物。
