title: Hypermutability of a UV-sensitive aphidicolin-resistant mutant of Chinese hamster fibroblasts.
abstract: An ultraviolet light (UV)-sensitive thymidine auxotroph of Chinese hamster V79 cells that exhibits pleiotropic effects such as a high level of deoxycytidine triphosphate, slow growth, sensitivity to cytidine, and high frequencies of site-specific bromodeoxyuridine-dependent chromosomal aberrations was selected by its resistance to aphidicolin. The UV-induced mutability of this mutant and one of its revertants, which retains some of the phenotypes listed above, was studied in 3 mutation assay systems. The results showed that the mutant was hypermutable for ouabain and diphtheria-toxin-resistant mutations compared to wild-type V79 cells at the same UV dose or the same survival level. The mutant exhibits a delayed expression of maximal frequency of induced 6-thioguanine-resistant mutants. When maximal frequencies are compared at the same UV dose, the mutant also has higher mutation frequencies at the hypoxanthine-guanine phosphoribosyl transferase locus. The revertant was similar to the wild-type in UV sensitivity and mutability. Our results showed that UV sensitivity and hypermutability are correlated and controlled by a single gene. Thymidine auxotrophy or nucleotide pool imbalance apparently did not contribute to the UV sensitivity and mutability of the mutant.
mesh_terms: D000818:Animals; D016590:Aphidicolin; D002478:Cells, Cultured; D002875:Chromosomes; D006224:Cricetinae; D003412:Cricetulus; D004167:Diphtheria Toxin / Q000235:genetics; D004224:Diterpenes / Q000494:pharmacology*; D004351:Drug Resistance; D005347:Fibroblasts; D005796:Genes; D009154:Mutation; D010042:Ouabain / Q000235:genetics; D013866:Thioguanine; D014466:Ultraviolet Rays
chemical_list: D004167:Diphtheria Toxin; D004224:Diterpenes; D016590:Aphidicolin; D010042:Ouabain; D013866:Thioguanine