The tardigrade Hypsibius exemplaris dramatically upregulates DNA repair pathway genes in response to ionizing radiation [Bleo_RNA-seq]

Tardigrades can survive remarkable doses of ionizing radiation, up to about 1000 times the lethal dose for humans. How they do so is incompletely understood. We found that the tardigrade Hypsibius exemplaris suffers DNA damage upon gamma irradiation, but damage is repaired. We show that tardigrades have a specific and robust response to ionizing radiation: irradiation induces a rapid and dramatic upregulation of many DNA repair genes. By expressing tardigrade genes in bacteria, we validate that increased expression of some repair genes can suffice to increase radiation tolerance. We show that at least one such gene is necessary for tardigrade radiation tolerance. Tardigrades' ability to sense ionizing radiation and massively upregulate specific DNA repair pathway genes may represent an evolved solution for maintaining DNA integrity. Overall design: To identify genes that are enriched following Bleomycin exposure, Hypsibius exemplaris were exposed to 0 mg/mL (untreated), 10 µg/mL, 100 µg/mL, or 1 mg/mL Bleomycin for 24 hours. We then performed gene expression profiling analysis from data obtained from 3 replicates of each dose of Bleomycin and compared to the 0 mg/mL (untreated) samples.