GENOMIC VARIATION OF LABORATORY STRAINS A ND NATURAL-POPULATIONS OF DROSOPHILA-MELANOGASTER UNDER X-IRRADIATION

The spontaneous and X-ray-induced mutation rates and spectrums were es timated in laboratory strains and natural populations of Drosophila me lanogaster from the Chernobyl meltdown area, Laboratory strains Oregon R and y(2)W(a4) were stable. In all natural populations, the spontane ous mutation rate was an order of magnitude higher (10(-3)) than in la boratory strains. Irradiation at a total dose of 3000 R was shown to i nduce genetic instability in the stable laboratory strain y(2)w(a4) an d to increase the mutation rate and spectrum range in the unstable nat ural population P-1. A high level of genetic instability was observed both in the first and second generations. Genetic analysis by means of classical genetic and molecular methods was performed; in crosses, a collection of spontaneous and induced mutants was used. The molecular genetic nature of mutations at the white and cur loci was analyzed by Southern blot-hybridization. Mutations at the white locus were shown t o result bath from transposition and recombination events; cut mutatio ns were caused by deletions.