Sex- and cell-specific regulation of yolk polypeptide genes introduced into Drosophila by P-element-mediated gene transfer.

To find whether cis-acting regulatory sequences necessary for sex- and cell-specific expression of two yolk polypeptide genes (Yps) reside near the structural genes themselves, we introduced a 5.0-kilobase genomic DNA segment containing a 3' truncated Yp1 and a complete Yp2 into five different autosomal locations by P-element-mediated gene transfer. Transcripts from the introduced Yp1 were not found in male flies but appeared on a normal developmental schedule in adult females, accumulating in their body walls and ovarian follicles but not in guts or malpighian tubules. Protein from the introduced Yp2 allele was present in female hemolymph and vitellogenic ovaries but was lacking from male hemolymph. We conclude that sequences necessary for the correct stage-, cell-, and sex-specific expression of the Yp1 and Yp2 genes are included in this genomic fragment. These results combined with published work suggest that two tissue-specific, cis-acting, bidirectional, positive regulatory elements placed on either side of a centrally located HindIII site govern expression of both Yp genes--one element specific for fat body and the other specific for ovarian follicle cells.