Temporal Gene Expression of the Cyanobacterium Arthrospira in Response to Gamma Rays

The edible cyanobacterium Arthrospira sp. PCC 8005 is resistant to ionising radiation. The cellular mechanisms underlying this radiation resistance are, however, still largely unknown. Therefore, additional molecular analysis was performed to investigate how these cells can escape from, protect against, or repair the radiation damage. Arthrospira cells were shortly exposed to different doses of 60Co gamma rays and the dynamic response was investigated by monitoring its gene expression and cell physiology at different time points after irradiation. The results revealed a fast switch from an active growth state to a kind of 'survival modus' during which the cells put photosynthesis, carbon and nitrogen assimilation on hold and activate pathways for cellular protection, detoxification, and repair. The higher the radiation dose, the more pronounced this global emergency response is expressed. This study provides new insights into phasic response and the cellular pathways involved in the radiation resistance of microbial cells, in particularly for photosynthetic organisms as the cyanobacterium Arthrospira.