[Comparative effectiveness of different types of radiation in the induction of gene mutations: basic and applied aspects].

Large-scale radiation-genetic studies on bacterial cells (E. coli) and Drosophila (D. melanogaster) using methods like an analysis of mutations of some structural genes and assessment of the frequency of mutations with relation to survival have shown for the first time that the efficacy of neutrons (E = 0.85 MeV) in the induction of gene mutations in Pro- and Eukaryotae is much lower than that of weak ionizing radiation with the same survival. Some features of radiation mutagenesis in a Drosophila mutant c(3)G defective in genetic recombination were described. A low level of the frequency of radiation-induced mutations typical of this mutant was also characteristic for some E. coli rec--mutants. A fact earlier reported for bacteria consisting in a higher (than one could expect extrapolation of lethal-sublethal irradiation doses to small ones) frequency of gene mutations in the range of relatively small absorbed doses of gamma-irradiation (the survival rate being not lower than 80%) was also first established for Drosophila. The importance of these entirely new facts for the theory of mutations in radiation genetics are briefly discussed.