[Spontaneous mutation rate in clones of Chinese hamster cells differing in UV sensitivity]

The paper deals with a study of the rate of spontaneous mutations to 6-mercaptopurine resistance in cells of CHR2, CHS2 clones differing in sensitivity to the lethal and mutagenic effects of UV irradiation. An enhanced UV-sensitivity of CHS2 clone was shown earlier to be the result of a disturbance in postreplication DNA repair. Estimation of spontaneous mutation rate in the HPRT locus demonstrated that it is similar for both clones (1.5 to 1.8 X 10(-5) per cell, per generation). The defect of postreplication DNA repair in Chinese hamster cells was found to be unrelated to the increase in spontaneous mutability. The possible role of the repair process in the mechanism of initiation of spontaneous and induced mutations in Chinese hamster cells with the enhanced UV-sensitivity is discussed.