Repair Replication of DNA in vivo

It has been postulated that damaged DNA in bacteria and in some other cellular systems is subject to repair by a mechanism that involves the replacement of the defective single-strand regions with a short stretch of oligonucleotide utilizing the complementary base pairing information in the intact strand. This mode of repair was suggested by Setlow and Carrier (1964) and by Boyce and Howard-Flanders (1964) following their demonstration that ultraviolet light (UV) induced thymine dimers are selectively released from the DNA of certain UV resistant strains of bacteria in vivo. Direct physical evidence for the postulated reconstruction of the excised region was obtained in our laboratory in a study of the qualitative nature of DNA replication in UV-irradiated bacteria (Pettijohn and Hanawalt, 1963, 1964). In this contribution we will outline the procedure by which repair replication can be demonstrated in vivo and we will examine the evidence that the observed mode...