Relationship of DNA repair processes to mutagenesis and carcinogenesis in mammalian cells. Progress report, October 1, 1982-September 30, 1983

Two strains of murine L5178Y lymphoma cells have been characterized as to their sensitivity to the lethal and mutagenic effects of ionizing radiation, delivered at either high (53 Gy/hr) or low (0.02 Gy/hr) dose rates. Both strains were less sensitive to the lethal effects of low dose-rate radiation than high dose-rate radiation, but the differences was much greater in the case of strain LY-R. Strain LY-R was also less sensitive to the mutagenic effects of low dose-rate radiation than high dose-rate radiation, but the dose-rate dependence was much less than in the case of the lethal effects. In the case of strain LY-S, a higher mutation frequency was obtained at the low dose rate than at the high dose rate. Although strain LY-S was more sensitive to the lethal effects of ionizing radiation, it was more poorly mutable following treatment with alkylating agents and UV radiation. We suggest that strain LY-S may be deficient in an error-prone repair process. Comparison of the DNA repair capabilities of the two strains has revealed that the rejoining to the hypersensitivity of strain LY-S to the lethal effects of ionizing radiation is under investigation