Repair Replication and Unscheduled DNA Synthesis in Synchronous Mammalian Cells

Summary

Mammalian cell populations, synchronized by the excess thymidine double block technique, were irradiated in the G₂ phase of the mitotic cycle with u.v. or ⁶⁰Co radiations then pulsed with ³H 5-bromo-2-deoxyuridine. Repair replication was demonstrated in each of the three cell lines investigated after u.v.-irradiation; but no evidence for repair was detected after ⁶⁰Co-irradiation. The extent of repair did not increase with dose. A correlation between repair replication and unscheduled DNA synthesis was observed.