DNA repair and replication in radiation-sensitive and -resistant mouse lymphoma cells gamma-irradiated under aerobic and hypoxic conditions.

Repair of DNA damage induced by gamma-rays was studied by the DNA unwinding technique in two strains of murine L5178Y lymphoma cells. These strains differ in sensitivity to low LET radiation by a factor of 1.4. No difference was found in the rate of DNA strand break rejoining during the first 3 hours after irradiation with 2 or 10 Gy of gamma-rays under aerobic conditions either at 0 degrees C or at room temperature. Also, the lesions inflicted by irradiation with 5 Gy of gamma-rays under hypoxia at room temperature were repaired by both strains at the same rate. The final level of unrejoined DNA strand break was the same in both strains, under all conditions examined, within the limits of resolution of the DNA unwinding technique. The rates of DNA chain elongation were also similar in both strains after irradiation under hypoxic or aerobic conditions.