A small region surrounding the distal promoter of the hunchback gene directs maternal expression.

While maternally provided factors play essential roles in the earliest processes of embryogenesis, little is known about the control of female germline-specific gene expression. Primer extension analysis and in situ hybridization experiments demonstrate that in adult Drosophila females, transcripts of the gap gene hunchback (hb) are produced only by the distal (P1) promoter and that this expression is largely restricted to the ovarian nurse cells. A deletion analysis of the hb promoter using lacZ reporter constructs defines a 1.2-kb genomic DNA fragment surrounding the P1 promoter that is sufficient to reproduce the wild-type pattern of hb ovarian transcript accumulation. By contrast, the subfragments of this region we have tested fail to direct specific ovarian expression.