Sister-chromatid exchanges are not directly related to 6-thioguanine-resistant mutations induced by ultraviolet radiation in V79 Chinese hamster cells.
A comparison of the effects of caffeine on ultraviolet (UV)-induced sister-chromatid exchanges (SCEs) and 6-thioguanine-resistant (6-TGr) mutations was attempted in order to study how the SCE mechanism correlates with mutagenesis. The linear UV dose-mutation relation indicated that the presence of 1mM caffeine during the 6-day expression period prior to the 6-TG selection did not alter the 6-TGr mutation induction rate. However, 1mM caffeine synergistically elevated the rate of UV-induced, immediate SCE formation, but did not alter the delayed SCE frequency in the 6-day survivors. These results indicate a clear dissociation of SCE from mutation, and suggest that SCE formation may not primarily involve the mutagenic process, but may rather be an error-proof mechanism that can tolerate some of DNA lesions.
D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D002460:Cell Line; D002999:Clone Cells; D006224:Cricetinae; D003412:Cricetulus; D003434:Crossing Over, Genetic / Q000187:drug effects*; D008168:Lung; D009154:Mutation; D012854:Sister Chromatid Exchange / Q000187:drug effects*; D013866:Thioguanine / Q000378:metabolism*; D014466:Ultraviolet Rays
D002110:Caffeine; D013866:Thioguanine