Mutation induction in a radiation-sensitive variant of mammalian cells

Ultraviolet light (UV)-induced mutations were compared between a UV-sensitive variant and its parental mouse lymphoma cell line. The variant was originally isolated for its sensitivity to 4-nitro-quinoline-1-oxide by employing a replica plating method and proved to be sensitive to the killing by UV as well. Caffeine potentiation of UV killing was observed to a similar extent in the variant and the parental cells, indicating that the caffeine-insensitive process is responsible for UV sensitivity in the variant. The induced mutation frequency as determined by resistance to 6-thioguanine was higher in the variant than in the parental cells per unit dose of UV as well as at the comparable survival level.