INTERACTIONS OF DECAPENTAPLEGIC, WINGLESS, AND DISTAL-LESS IN THE DROSOPHILA LEG

The genes decapentaplegic, wingless, and Distal-less appear to be inst rumental in constructing the anatomy of the adult Drosophila leg. In o rder to investigate how these genes function and whether they act coor dinately, we analyzed the leg phenotypes of the single mutants and the ir inter se double mutant compounds. In decapentaplegic the tarsi freq uently exhibit dorsal deficiencies which suggest that the focus of gen e action may reside dorsally rather than distally. In wingless the tar sal hinges are typically duplicated along with other dorsal structures , confirming that the hinges arise dorsally. The plane of symmetry in double-ventral duplications caused by decapentaplegic is virtually the same as the plane in double-dorsal duplications caused by wingless. I t divides the fate map into two parts, each bisected by the dorsoventr al axis. In the double mutant decapentaplegic wingless the most ventra l and dorsal tarsal structures are missing, consistent with the notion that both gene products function as morphogens. In wingless Distal-le ss compounds the legs are severely truncated, indicating an important interaction between these genes. Distal-less and decapentaplegic manif est a relatively mild synergism when combined.