Both early and late Drosophila chorion gene promoters confer correct temporal, tissue and sex specificity on a reporter Adh gene.

In vivo transformation studies have been performed using fusion constructs of chorion DNA and the alcohol dehydrogenase (Adh) structural gene. The results indicate that almost exclusively 5' flanking DNA regions of the early (s36) and late (s15) chorion genes suffice for conferring normal chorion developmental specificity (sex, tissue and temporal) on the reporter gene. In the case of s15, the proximal 5' flanking DNA up to position -370 is sufficient for specificity. However, quantitative analysis indicates that one or more elements within or downstream of the s15 gene are required, either transcriptionally or post-transcriptionally, for attainment of an mRNA level comparable to that of the endogenous s15 gene (corrected for amplification); in the absence of such element(s), the average level of Adh transcript produced by fusion gene constructs is 18-fold lower.