[Mutagenic effect on Escherichia coli bacteria of 8-hydroxy-2'-deoxyguanosine--a DNA base damage product induced by oxygen radicals and ionizing radiation].
The effect of 8-oxo-2'-deoxyguanosine (8-oxo-dG) (8-hydroxydeoxyguanosine)--a DNA base damage product induced by oxygen radicals and irradiation on survival and mutagenesis in Escherichia coli strains C-600 and P-687 was investigated. Survival and mutagenesis curves, in dependence of 8-oxo-dG concentrations in the medium, ranging from 0.2 through 10 mM, were obtained. Bacterial survival at all 8-oxo-dG concentrations tested was shown to be no lesser than in the control. The mutagenic effect of 8-oxo-dG was tested by frequency of reversions in the absence of leucine and threonine. A non-linear dependence of mutagenesis on the concentration was observed. Linear increase in the amount of revertants took place at concentrations of 8-oxo-dG lower than 1 mM, and being kept constant at higher concentrations. Induction of SOS repair under the action of 8-oxo-dG in E. coli PQ37 strain was estimated according to alteration of activity of beta-galactosidase in the SOS chromotest. Weak induction of the SOS response was observed within the wide range of 8-oxo-dG concentration values, which points to a lack of genotoxicity and independence of mutagenesis on SOS repair.