CONTROL OF DROSOPHILA ADULT PATTERN BY EXTRADENTICLE

The homeobox gene extradenticle (exd) acts as a cofactor of the homeot ic genes in the specification of larval patterns during embryogenesis. To study its role in adult patterns, we have generated clones of muta nt exd(-) cells and examined their effect on the different body parts. In some regions, exd(-) clones exhibit homeotic transformations simil ar to those produced by known homeotic mutations such as Ultrabithorax (Ubx) labial (lab), spineless-aristapedia (ss(a)) or Antennapedia (An tP). In other regions, the lack of exd causes novel homeotic transform ations producing ectopic eyes and legs. Moreover, exd is also required for functions normally not associated with homeosis, such as the main tenance of the dorsoventral pattern, the specification of subpatterns in adult appendages or the arrangement of bristles in the mesonotum an d genitalia. Our findings indicate that exd is critically involved in adult morphogenesis, not only in the homeotic function but also in sev eral other developmental processes.