Analysis of transcriptional regulation of the s38 chorion gene of Drosophila by P element-mediated transformation.

Transcriptional regulation of the s38 chorion gene was studied using P element-mediated germline transformation. A 5.27 kb DNA fragment containing the s38 gene and 5'- and 3'-flanking sequences, was tested for its ability to be transcribed with correct developmental specificity. Five single-insert transformed lines were generated by microinjection of this DNA fragment cloned into a marked P element transformation vector. In each line, the transformed gene was transcribed according to the precise developmental pattern followed by the native s38 gene. The 1.3 kb at the 5' end of this tested fragment was fused to the E. coli lac z gene. This fragment was also capable of initiating transcription of E. coli lac z RNA with the developmental profile of the native s38 gene. In vitro deletion studies are underway to determine which sequences in the 1.3 kb fragment are necessary for regulating the developmental expression of the gene.