Involvement of the Excision Repair System in Recovery of Bacteriophage from γ-ray Damage Sustained under Oxic and Anoxic Conditions

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Abstract
Bacteriophages T1 and λvir irradiated with gamma-rays under anoxic conditions show a higher survival when assayed on an Escherichia coli Hcr+ strain than when assayed on a Hcr− derivative (uvrA B or C). Hardly any difference in sensitivity is seen for phage irradiated in the presence of oxygen. Assayed on a strain deficient in DNA polymerase I, the survival of irradiated T1 is lower than on the wild-type parent, for irradiation under both oxic and anoxic conditions. It is concluded that the damage sustained under oxic conditions, which is repaired by the excision repair system, does not need the products coded by the uvr genes, whereas part of the damage inflicted under nitrogen does. This conclusion is supported by the observation that the sensitivities of bacteriophages T4D and T4Dv1 for γ-rays differ under nitrogen, but are identical under oxygen.