The effect of thymidine on the induction of micronuclei by alkylating agents in V79 Chinese hamster cells.
Incubation in thymidine-containing medium resulted in increased lethality and micronucleus frequency in V79 cells treated with ethyl nitrosourea (ENU), methyl nitrosourea (MNU) and ethyl methane-sulphonate (EMS) but not with methyl methanesulfonate (MMS). Thymidine had no effect in ENU treated HeLa cells. In V79 cells, the presence of thymidine during post-treatment DNA replication was necessary for the effect. It is suggested that the increase in chromosome damage was the result of an increased O6-alkylguanine-thymine mispairing in cells which are defective in the repair of O6-alkylguanine. Treatment of V79 cells with O6-ethylguanine resulted in increased production of both micronuclei and polyploid cells. These effects might be explained by spindle dysfunction caused by the alkylated guanine.
D000477:Alkylating Agents / Q000633:toxicity*; D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D002470:Cell Survival / Q000187:drug effects; D002869:Chromosome Aberrations; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D006147:Guanine / Q000031:analogs & derivatives / Q000494:pharmacology; D009154:Mutation / Q000187:drug effects*; D013936:Thymidine / Q000494:pharmacology*
D000477:Alkylating Agents; C007673:6-ethylguanine; D006147:Guanine; D004247:DNA; D013936:Thymidine