Kinetics of induction of sister-chromatid exchanges by X-rays through two cell cycles.
V79 Chinese hamster cells were exposed to X-rays at various times through the two cell cycles required to obtain harlequin-stained chromosomes. A two-fold SCE enhancement was found between the first and the second G1 phase when BrdUrd was incorporated during the first S phase only. This BrdUrd effect was not found when MNNG was used. Furthermore, the kinetics of SCE and aberrations were different, suggesting two separate mechanisms for their formation: SCE activity takes place when DNA damage occurs before the DNA replication, and aberration activity when the DNA damage occurs chiefly after the DNA replication.
D000818:Animals; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D003078:Colchicine / Q000494:pharmacology; D006224:Cricetinae; D003412:Cricetulus; D003434:Crossing Over, Genetic / Q000528:radiation effects*; D007700:Kinetics; D008168:Lung; D008769:Methylnitronitrosoguanidine / Q000494:pharmacology; D012854:Sister Chromatid Exchange / Q000187:drug effects / Q000528:radiation effects*
D008769:Methylnitronitrosoguanidine; D001973:Bromodeoxyuridine; D003078:Colchicine