Development of a liquid-holding technique for the study of DNA-repair in human diploid fibroblasts.
Liquid-holding conditions can be obtained for human diploid skin fibroblasts by keeping confluent cultures stationary over periods of 7 days or longer by means of conditioned medium. Under this condition recovery of radiation damage induced by ultraviolet light or X-rays is observed as an increase in cloning efficiency. The amount of recovery when expressed in a dose-modifying-factor appears higher than in bacteria and yeast. The repair-deficient human cell strains XP25Ro and XP7Be (xeroderma pigmentosum from complementation groups A and D respectively) exhibit less but still discernible recovery after UV-irradiation and the same was observed for AT5Bi (ataxia telangiectasia) after X-irradiation. Experiments on mutation induction indicated that the repair which takes place during liquid holding of UV-irradiated XP7Be cells reduces the mutant frequency considerably while after liquid holding of UV-irradiated wild-type cells the same or lower mutant frequencies were found for the lower exposures and the same or higher mutant frequencies for the higher exposures.
D002460:Cell Line; D003470:Culture Media; D046508:Culture Techniques / Q000379:methods*; D004247:DNA / Q000528:radiation effects; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts; D005821:Genetic Techniques; D006801:Humans; D008297:Male; D014466:Ultraviolet Rays; D014965:X-Rays
D003470:Culture Media; D004247:DNA