title: Killing and mutation induction in quiescent V79 cells as influenced by nalidixic acid.
abstract: Involvement of topoisomerase II in the repair of damage by N-methyl-N'-nitro-N-nitrosoguanidine, UV light and gamma-rays has been studied using quiescent V79 cells. In each case, the presence of nalidixic acid, the inhibitor of topoisomerase II, decreased the survival through suppression of potentially lethal damage repair. There was also an increase in the yield of mutants because of such suppression. The observations were in contrast with those made with exponential cells in the following aspects: (a) density-inhibited cells showed a positive response to suppression of topoisomerase II activity after treatment with UV light and gamma-rays and (b) for MNNG exposure, mutational yield increased instead of decreasing as in exponential cells. The results showed that topoisomerase II played an important part in the repair of damage of density-inhibited cells.
authors.affiliation: Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Calcutta, India.
authors.forename: R
authors.initials: R
authors.lastname: Ghosh
authors.forename: S B
authors.initials: SB
authors.lastname: Bhattacharjee
mesh_terms: D000818:Animals; D002455:Cell Division; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects*; D003260:Contact Inhibition; D006224:Cricetinae; D003412:Cricetulus; D004260:DNA Repair / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004357:Drug Synergism; D005720:Gamma Rays; D008769:Methylnitronitrosoguanidine; D009154:Mutation; D009268:Nalidixic Acid / Q000494:pharmacology*; D011838:Radiation-Sensitizing Agents; D059005:Topoisomerase II Inhibitors; D014466:Ultraviolet Rays
chemical_list: D011838:Radiation-Sensitizing Agents; D059005:Topoisomerase II Inhibitors; D008769:Methylnitronitrosoguanidine; D009268:Nalidixic Acid