DELETION SCANNING OF THE REGULATORY SEQUENCES OF THE FBP1 GENE OF DROSOPHILA-MELANOGASTER USING P-TRANSPOSASE-INDUCED DEFICIENCIES

A procedure permitting deletion scanning of potential cis-regulatory s equences within a transgene whose genomic position remains fixed was a pplied to the study of the upstream sequences of the ecdysteroid-induc ible Fat-body protein-1 (Fbp1) gene. Deficiencies were induced in a Fb p1:Adh fusion transgene by means of a secondary P transposase mutagene sis. Phenotypic and molecular screens were used to select mutant trans posons that retained their original genomic location and carried a del etion affecting the Fbp1 sequences but not the Adh reporter gene. Mole cular mapping of the deletion breakpoints was achieved by sequence ana lysis and expression of the reporter gene was quantified by measuremen t of ADH activity. This procedure was efficient in detecting cis-actin g elements, even those with moderate effects on levels of gene express ion. For example, we have succeeded in identifying a negative regulato ry element Deletion of this element leads to a 50% increase in the rep orter ADH activity. This element binds the transcription factor AEF-1. In addition, we have detected a strong, positively acting element con tained within a 32-bp region located immediately upstream of an ecdyso ne-response element.