During Drosophila development, the legs, wings and body wall develop from the imaginal discs, groups of cells that first arise from the embryonic ectoderm. The specification of imaginal disc cells into the progenitors of adult structures involves the signalling proteins Wingless (Wg)and Decapentaplegic (Dpp). On , Weihe et al. report that the zinc finger proteins Elbow (El) and No ocelli (Noc) mediate Wg and Dpp function during appendage specification. They show that the expression of El and Noc in the presumptive distal cells of the leg and wing imaginal discs, which is regulated by Wg and Dpp, represses the expression of the body wall-specifying genes homothorax and teashirt in the appendage primordia. The researchers also reveal subtle differences in the regional requirements for El and Noc between the leg and wing primordia, and they go on to discuss the possible implications of this for our understanding of appendage development.
