IDENTIFICATION OF 2 REGIONS FROM THE DROSOPHILA-DECAPENTAPLEGIC GENE REQUIRED FOR EMBRYONIC MIDGUT DEVELOPMENT AND LARVAL VIABILITY

The Drosophila decapentaplegic (dpp) gene, a member of the transforming growth factor-beta family, is required for dorsal/ventral pattern formation and midgut and imaginal disk development. We have identified a 3-kb upstream regulatory region necessary for dpp expression in the visceral mesoderm of the gastric caeca primordia and a second 2.5kb upstream regulatory region necessary for dpp expression in the midgut visceral mesoderm corresponding to a portion of abdominal segments 1 and 2 (parasegment 7). These regulatory regions act over a distance of up to 10 -kb on all four of the dpp promoters examined. Absence of dpp expression in the gastric caeca primordia caused defective development of the gastric caeca and a concomitant partial reduction in larval and pupal viability. Absence of dpp expression in the visceral mesoderm of parasegment 7 caused a reduction in the length of the central portion of the larval gut and a change in the morphology of the midgut cells in this region but had little effect on the survival of the animals to the adult stage. However, a larval lethal phenotype was observed when both the central portion of the larval midgut and the gastric caeca were defective. © 1993 by Academic Press, Inc.