Transcriptome analysis of the tardigradeHypsibius exemplarisexposed to the DNA-damaging agent bleomycin

Tardigrades are microscopic animals that are renowned for their capabilities of tolerating near-complete desiccation by entering an ametabolic state called anhydrobiosis. However, many species also show high tolerance against radiation in the active state as well, suggesting cross-tolerance via the anhydrobiosis mechanism. Previous studies utilized indirect DNA damaging agents to identify core components of the cross-tolerance machinery; however, it was difficult to distinguish whether transcriptomic changes were the result of DNA damage or residual oxidative stress. To this end, we performed transcriptome analysis on bleomycin-exposed Hypsibius exemplaris . We observed induction of several tardigrade-specific gene families that may be the core components of the cross-tolerance mechanism. We also identified an enrichment of the tryptophan metabolism pathway, which metabolomic analysis suggested the engagement of this pathway in stress tolerance. These results provide several candidates for the core component of the cross-tolerance, as well as possible anhydrobiosis machinery.