PS2 INTEGRIN REQUIREMENTS IN DROSOPHILA EMBRYO AND WING MORPHOGENESIS

The Drosophila inflated (if) gene encodes the αPS2 subunit of the PS integrins. We describe the generation of new if mutations, their lethal embryonic phenotype, and experiments that examine the spatial and temporal requirements for integrins in adult wing morphogenesis. Embryos hemizygous for either new allele, ifA7 or ifB2, make reduced amounts of αPS2. In a variety of genetic tests, these alleles behave similarly to ifh27e, which makes no detectable α(PS2), and all three alleles display the same embryonic phenotype. We therefore conclude that all of the lethal alleles retain little or no wild-type αPS2 function. As seen for strong mutations at the myospheroid (mys) locus, which encodes the βPS integrin subunit, if mutants show extreme defects in somatic muscle attachments and in midgut morphogenesis. Unlike mys, however, there is no dorsal herniation of the if mutant embryos. With respect to wing morphogenesis, clonal analysis experiments demonstrate that if+ function is required only in cells of the ventral wing surface. We have rescued the wing blister phenotype of double mutants for the hypomorphic mysnj42 and if3 alleles using a heat shock-inducible mys+ transgene. By varying times of transgene induction, we find that integrin function is required from very early in metamorphosis until at least the last 24-48 hr of wing development. © 1993 by Academic Press, Inc.