Phenomenological theory of repair kinetics of ultraviolet irradiated Lambda phage

Role of post-replication and excision repair mechanism in the induction of Trp+ revertants of UV-irradiated Escherichia coli

Both the post-replication and the excision repair mechanism participate in the induction of Trp+ revertants in Escherichia coli B/r Hcr+ thy trp after a UV-irradiation. At low radiation doses (surviving cell fraction greater than 10(-1) most Trp+ reversions are due to post-replication repair mechanism while at high doses (surviving cell fraction less than 10(-1)) the Trp+ reversions arise probably as the result of an inaccurate excision repair. The absolute accuracy of repair processes decreases with increasing radiation dose.

Reactivation of photoinactivated single-stranded DNA bacteriophage phi X174 by UV-irradiated Escherichia coli cells

Reactivation of single-stranded DNA phage, photodynamically inactivated in the presence of proflavine sulfate, by three isogenic Escherichia coli strains having different DNA repair capabilities has been studied. It was found that reactivation of photoinactivated phiX174 was possible only if the host cells were recombination proficient (recA(+)) and had been lightly irradiated with UV light prior to infection; the presence of the uvrA(+) gene was not essential. Only a small part of the proflavine-mediated photodynamic damage in phiX174 could be repaired in this fashion. Burst sizes of reactivated phages were, however, comparable to those of normal unirradiated phages.