Regulation of the P element transposon in Drosophila melanogaster involves a cellular, maternally-transmitted, repressive condition known as P cytotype. The major focus of this project will be a transinteraction where the repressor that constitutes P cytoype affects the expression of certain genes with P elements inserts. This unusual interaction provides a model for the action of the P element repressor, and is a sensitive assay for the presence of repressor. A large sample of affected alleles will be gathered, primarily at the singed locus. These alleles will be characterized molecularly, and Northern analysis of singed transcripts will illuminate the mechanisms involved. The cis requirements of the P inserts will be examined using deletions induced by P transposase. An additional sensitive assay for the repressor is the ability to suppress in trans a special, stable, transposase-producing element called 2-3(99B). This element will be characterized genetically and molecularly to determine the basis for its unusual properties of stability despite extraordinary, and apparently unregulated, transposase activity. Together these assays provide the means to continue an examination of the nature of the P element repressor. This work will improve our understanding of a major transposon in Drosophila, which will facilitate the understanding of comparable DNA parasites in other organisms.
