The Drosophila genes disconnected and disco-related together specify development of adult legs

Abstract

In the fruit fly, Drosophila melanogaster, specification of the legs begins during embryogenesis when Wingless signaling induces small groups of cells to form the imaginal disc primordia in the thoracic segments. This signal initiates expression of transcription factors that will later be used to pattern the legs. The paralogous genes disconnected and disco-related encode transcription factors that are expressed in the disc primordia during early embryogenesis, and their expression continues in the leg discs during larval and pupal stages. The importance of these two genes in establishing the leg development trajectory was indicated by our previous observation that ectopic expression of either gene in the wing discs cells caused legs to develop in place of wings. However, because of their redundancy and requirement for survival during embryogenesis, we were unable to define their role in development of the adult legs. Here, we report loss-of-function analyses of the disco genes during development of the legs. We discovered that loss of both genes functions causes both truncation of the distal leg with apparent overgrowth of proximal regions and complete loss of legs and ventral thoracic body patterning. At the molecular level we noted reduction or loss of signaling and transcription factors that pattern the proximal-distal axis of the legs. We conclude from these studies that the disco genes promote leg development through regulation of signaling processes, but also by stabilizing expression of the leg determination gene network.