Isolation of a mutant cell line derived from ICR 2A frog cells hypersensitive to the induction of nondimer DNA damage by solar ultraviolet radiation

A mutant cell line DRP 36, hypersensitive to nondimer DNA damage induced by exposure of cells to the Mylar-filtered solar ultraviolet (UV) radiation produced by a fluorescent sunlamp plus photoreactivating light (PRL) was isolated from the haploid ICR 2A frog cell line. The D₀ for mutant cells exposed to this solar UV source was 3.3 kJ/m² compared with a D₀ of 7.3 kJ/m² for the parental ICR 2A cells. In contrast, DRP 36 and ICR 2A cells exhibited similar levels of survival following 254-nm irradiation which causes the induction primarily of pyrimidine dimers. The cross-sensitivity to additional DNA damaging agents was examined, and it was determined that the DRP 36 cells are also hypersensitive to treatment with γ-rays, ethyl methane sulfonate (EMS), cis-dichlorodiammine platinum (II) (DDP), and 4-nitroquinoline oxide (4-NQO) while exhibiting normal sensitivity to l-phenylalanine mustard (L-PAM), 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) and mitomycin C (MMC).