Relationship of DNA repair and chromosome aberrations to potentially lethal damage repair in X-irradiated mammalian cells.
By the alkaline elution technique, the repair of x-ray-induced DNA single strand breaks and DNA-protein cross-links was investigated in stationary phase, contact-inhibited mouse cells. During the first hour of repair, approximately 90% of x-ray induced single strand breaks were rejoined whereas most of the remaining breaks were rejoined more slowly during the next 5 hr. The number of residual non-rejoined single strand breaks was approximately proportional to the x-ray dose at early repair times. DNA-protein cross-links were removed at a slower rate - T 1/2 approximately 10-12 hr. Cells were subcultured at low density at various times after irradiation and scored for colony survival (potentially lethal damage repair), and chromosome aberrations in the first mitosis after sub-culture. Both cell lethality and the frequency of chromosome aberrations decreased during the first several hours of repair, reaching a minimum level by 6 hr; this decrease correlated temporally with the repair of the slowly rejoining DNA strand breaks. The possible relationship of DNA repair to changes in survival and chromosome aberrations is discussed.
D000818:Animals; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D003114:Colony-Forming Units Assay; D004247:DNA / Q000528:radiation effects*; D004260:DNA Repair; D004277:DNA, Single-Stranded / Q000032:analysis; D003852:Deoxyribonucleoproteins / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D004622:Embryo, Mammalian; D005347:Fibroblasts / Q000528:radiation effects; D006863:Hydrogen-Ion Concentration; D007939:Leukemia L1210; D051379:Mice; D008809:Mice, Inbred C3H
D004277:DNA, Single-Stranded; D003852:Deoxyribonucleoproteins; D004247:DNA