Armored Terrestrial Tardigrades use Cryptogam-Host Cues of Pending Environmental Deterioration to Initiate Cryptobiosis.

Abstract

Abstract The mechanisms of the induction of extremotolerant states, a.k.a. cryptobiosis, in tardigrades are beginning to be explored. Armored tardigrades (Class: Heterotardigrada) living in limnoterrestrial environments are highly associated with desiccation-tolerant moss or lichen substrates that themselves produce numerous specialized metabolites during desiccation. Here we show that some of these metabolites can induce reversible cryptobiosis in their coexisting heterotardigrades in a dose-dependent manner. Coexisting eutardigrades, nematodes and rotifers however, show no such response to these molecules. The response-inducing metabolites belong to a class of soft-electrophilic flavonoid compounds, suggesting that they possibly interact with electrophile-responsive heterotardigrade proteomes related to their specific cryptobiotic traits. The ability to control when biological material enters a protective state increases the scope of bioengineering avenues to mitigate increasing environmental unpredictability on Earth and to inform near-future space-travel endeavors.