Requirements for integrins during Drosophila development.

The common beta subunit of the PS antigens of Drosophila is homologous with vertebrate integrins and is encoded by the lethal(1)myospheroid gene. We have generated flies mosaic for wild-type and mutant alleles of lethal(1)myospheroid using adult gynandromorphs and radiation-induced somatic crossing over. The defects observed in the gynandromorphs demonstrate widespread requirements for PS integrins during development especially in ventrally derived structures, which also show strong expression of PS beta integrin. Smaller lethal(1)myospheroid clones induced during larval development result in blister and vein defects in the wings and aberrant development of photoreceptor cells, demonstrating roles for PS integrins during development of both wings and eyes. PS integrins are required for the close apposition of the dorsal and ventral wing epithelia and for the proper arrangement of photoreceptor cells. However, many other adhesive and morphogenetic processes proceed normally in the absence of integrins containing the beta subunit encoded by lethal(1)myospheroid.