Role of DNA repair pathways in the recovery of a dried, radioresistant cyanobacterium exposed to high-LET radiation: implications for the habitability of Mars

Abstract If life ever appeared on Mars and if it did refuge into sub-superficial environments when surface conditions turned too hostile, then should have been periodically revived from the frozen, dormant state in order to repair accumulated damage reset survival clock zero for next phase. Thus, unravelling how long Earth microorganisms can cope with high-LET radiation mimicking long-term irradiation is fundamental get insights resilience of a microbial Martian subsurface over geological timescales that might taken advantage clement allowed DNA damage. The exposure dried cells radioresistant cyanobacterium Chroococcidiopsis sp. CCMEE 029 2 kGy heavy-ion (Fe ions) not significantly reduce its survival, although was accumulated. Upon rehydration, lesions were repaired as suggested by over-expression genes involved double strand breaks (DSBs), oxidized bases apurinic-apyrimidinic sites. Indeed, monitoring upon rehydration key role RecF homologous recombination repairing DSBs. While fact out eight BER system, only one up-regulated, absence generally induced UV radiation. In conclusion, non-significantly reduced exposed Fe-ion further expanded our appreciation putative subsurface. Moreover, also relevant searching Europa Enceladus where environment critically affect dormant, frozen forms.