title: Characterization of an X-ray-hypersensitive mutant of V79 Chinese hamster cells.
abstract: A V79 Chinese hamster cell line XR-V15B exhibiting hypersensitivity to X-ray has been isolated and characterized. Additionally to increased X-ray-sensitivity (approximately 8-fold, as judged by D10 values), cross-sensitivity to bleomycin (3-fold increase), 4NQO (3-fold), H2O2, EMS, MMS (2-fold) were observed also. No increased sensitivity to UV and MMC was found. Genetic complementation analysis indicates that XR-V15B belongs to the same complementation group as the X-ray-sensitive (xrs) mutants of Chinese hamster ovary (CHO) cells described by Jeggo (1985). Biochemical analysis of XR-V15B confirms this finding: the mutant showed a decreased ability to rejoin double-strand breaks induced by X-ray as measured by neutral elution. After 4 h of repair more than 50% of the double-strand breaks remain in comparison to 3% in V79 cells. No difference was observed between wild-type and XR-V15B cells in the initial number of single-strand breaks induced, in the kinetics of their rejoining and in the final level of unrejoined single-strand breaks. Treatment with 5-azacytidine did not have an effect on the reversion frequency of XR-V15B, contrary to the results obtained with the xrs mutants. XR-V15B has been grown in continuous culture for more than 3 months without evidence of reversion. The mutation induction by X-ray irradiation at the HPRT locus is not significantly increased in the mutant, but at doses giving the same degree of cell killing, XR-V15B cells are hypomutable.
authors: Department of Radiation Genetics and Chemical Mutagenesis, State University of Leiden, Sylvius Laboratories, The Netherlands.
authors: M Z
authors: MZ
authors: Zdzienicka
authors: Q
authors: Q
authors: Tran
authors: G P
authors: GP
authors: van der Schans
authors: J W
authors: JW
authors: Simons
mesh_terms: D000818:Animals; D001374:Azacitidine / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004260:DNA Repair; D005816:Genetic Complementation Test; D007041:Hypoxanthine Phosphoribosyltransferase / Q000235:genetics; D009153:Mutagens / Q000494:pharmacology; D009154:Mutation / Q000528:radiation effects; D014965:X-Rays
chemical_list: D009153:Mutagens; D004247:DNA; D007041:Hypoxanthine Phosphoribosyltransferase; D001374:Azacitidine