Epigenetic effect of the rad201(G1) mutation in a system with mobilization of nonautonomous P elements in Drosophila

The effect on P-element activity in somatic cells was studied for a repair mutation localized in the Drosophila genome in the region of the rad201 and Rad51C overlapping genes. When one of the parents carried nonautonomous P elements and the rad201 mutation and the other carried a P-transposase source, a high dominant pupal lethality was observed in the progeny heterozygous for the mutant allele and their sibs homozygous for the rad201 ⁺ wild-type allele. The sib response was due to the epigenetic effect of the rad201 mutation and was maintained through at least two generations. The specifics of the epigenetic effect are discussed in terms of its possible association with P transpositions and mitotic crossing over events determined by P transposase. Based on the results of genetic and genomic DNA analyses of the rad201 mutant, it was assumed that the phenomenon in question was determined by several genetic factors.