Induction kinetics of mutagenic DNA repair activity in E. coli following ultraviolet irradiation.

Ultraviolet mutagenesis of phage gamma is produced by host functions which are inducible by ultraviolet irradiation of the host cell. Induction kinetics and the half life of the inducible mutagenic DNA repair (SOS-repair) in E.coli have been determined using phage gamma assays. At 37 degrees C, both mutagenic and repair activities are maximal approximately 30 min following irradiation and decay with a half life of approximately 30 min. The presence of 100 mug/ml chloramphenicol during the first 40 min after irradiation completely abolishes induction of repair and mutagenesis. The ultraviolet induction pattern of SOS repair very much resembles that of gamma prophage in lysogenic induction (Monk and Kinross, 1975).