Sgs4 promoter fragment, extending from 850 bases 5' to 740 bases 3' to the transcription start site, drives the expression of a AvaII-HincII su(wa) fragment, extending from coordinate 767 in the first exon to coordinate 3502 in the fourth exon (coordinate system from FBrf0046125), followed by sequence encoding the lacZ reporter. SV40 polyadenylation signal and 3' nontranscribed sequences from su(wa) are present downstream of lacZ.