Distribution of Pyrimidine Dimers During Postreplication Repair in UV-irradiated Excision-deficient Cells of Escherichia Coli K12

During postreplication repair in excision-deficient mutants of Escherichia coli K-12, pyrimidine dimers are gradually lost from UV-irradiated DNA. Our data indicate that dimers are transferred, by a process which may involve genetic exchange, into daughter strands made after irradiation. Dimer transfer appears to continue through several rounds of replication, resulting in the gradual dilution of dimers into successive generations of DNA molecules.