UV mutagenesis and the CHO cell cycle

Cytotoxicity, mutagenesis, lesion induction and repair, and cellular recovery in Chinese hamster ovary (CHO) cells following ultraviolet light (UV) irradiation were investigated, primarily as a function of position in the cell cycle at the time of UV exposure utilizing mitotic harvest or serum starvation/refeeding protocols. CHO cells became increasingly more sensitive to the cytotoxic effects of UV as they traversed the cell cycle from G1 through early-mid S, then became significantly more resistant as they progressed into G2 and M. During cell cycle traverse, D/sub q/ values remained approximately constant, while those for D0 varied by more than a factor of two