Low intensity proton beam irradiation downregulates antioxidative protection in Aspergillus nidulans

Results showed upregulation of DNA repair, ribosome biogenesis, and protein ubiquitination genes, while glycolysis, and respiration genes were downregulated. Surprisingly, antioxidative enzyme genes were bulk-downregulated, increasing susceptibility to oxidative stress induced by menadione sodium bisulfite (MSB).

Experiments with an oxidative stress-sensitive mutant and MSB-pretreated cultures suggested that oxidative stress protection was crucial for surviving proton radiation. Therefore, down-regulation of antioxidant enzyme genes was not an adaptive response, but probably a consequence of a disturbance in redox sensing caused by reductive pre-hydrated electrons from water radiolysis. These results shed light on the complex interaction between radiation stress and fungal responses, which could lead to the potential exploitation of the underlying mechanisms in real space environments.