A Study of the Fertility of a Drosophila melanogaster MS Strain with Impaired Transposition Control of the gypsy Mobile Element

Abstract

The flamenco locus is one of the main components of the piRNA pathway of regulation of mobile genetic elements (MGEs) in Drosophila melanogaster. Mutations at this locus lead to an increase in the transposition activity of MGEs and, as a result, to genetic instability. In this paper, the fertility of a genetically unstable MS strain obtained more than 25 years ago and characterized by a mutation in the flamenco locus and the presence of a functionally active copy of gypsy retrotransposon was investigated. Complex violations of the ovarian morphology were revealed in the MS strain in females: defects in the follicular layer and ring channels, as well as degradation of trophocytes, which in turn led to a decrease in reproductive abilities. Analysis of the MS strain transcriptome showed a decrease in the expression level of 40 genes encoding chorionic proteins and expression specificity at different stages of follicle development. In the F1 and F2 hybrid females from the crosses of MS females with wild type males, restoration of reproductive abilities was observed, despite the fact that half of the F2 females had the flamenco genotype and genetic instability caused by transposition of gypsy (according to the ovo^(D) test). Moreover, the frequency of gypsy transposition in the hybrid F2 females with the flamenco genotype doubled in comparison with the MS strain females. Thus, the MS strain had acquired partial suppression of the flamenco phenotype and accumulated several recessive mutations in the genes that control oogenesis after cultivation for over 25 years.