title: The influence of repair systems on the presence of sensitive and resistant fractions in the relation of survival of colony-forming ability in Escherichia coli to UV exposure.
abstract: In the experimentally observed relationship between survival of colony-forming ability and the amount of exposure to ultraviolet light, two characteristics are generally found. First, sensitive and resistant components often show. Second, there is often a shouldered character to the survival. We present evidence that the first is largely due to the presence of active replication forks in the genome, and that the second is related to the operation of the recombinational repair system. We are able to describe our data in terms of a superposition of single and multiple-hit fractions and to show that the latter are greatly increased, in excision-repair-competent strains, by prevention of protein synthesis for 1 h prior to irradiation. Applying this analysis and treatment to a number of mutant strains enables us to make suggestions as to the interaction between recombinational and excision repair.
mesh_terms: D004260:DNA Repair; D004926:Escherichia coli / Q000528:radiation effects*; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000235:genetics; D005798:Genes, Bacterial; D011938:Rec A Recombinases / Q000235:genetics; D011995:Recombination, Genetic; D014466:Ultraviolet Rays
chemical_list: D011938:Rec A Recombinases; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V