Effect of Chemical Modifiers on Inactivation and Mutation-Induction by Gamma Radiation in Escherichia coli

Abstract

The effect of chemical sensitizing and protective agents on the rate of mutation induction by gamma radiation in strain WP2 of Escherichia coli B/r was studied. This organism will not grow in the absence of tryptophan but it mutates spontaneously at a very low rate, and under the influence of radiation at a much higher rate, to stable forms which can grow in the absence of tryptophan. Both inactivation and mutation-induction were apparently related to radiation dose by an exponential function in the absence of modifying agents; in their presence this was not always the case. The sensitizing agents oxygen and N-ethylmaleimide, and the protective agents cysteine, glycerol, dimethyl sulphoxide and thiourea, affected both the inactivating and mutation-inducing actions of radiation though not always to the same extent.