DORSAL WING, A LOCUS THAT AFFECTS DORSOVENTRAL WING PATTERNING IN DROSOPHILA

The wing imaginal disc is subdivided into a dorsal and a ventral compa rtments. A new dominant homeotic mutation. Dorsal wing(1)(Dlw(1)), tra nsforms ventral into dorsal compartment in heterozygotes. This phenoty pe is similar to one of the dominant phenotypes of Polycomb (Pc) mutan ts. In Pc Dlw(+)Pc(+) Dlw(1) double mutants, the transformation is gre atly enhanced. The recessive phenotype of Dlw(1) is the opposite to th e dominant phenotype. Dlw(1)/Dlw(1) somatic clones induced at any larv al stage differentiate only ventral pattern on both wing surfaces. Thi s effect is one of the somatic clone phenotypes of trithorax (trx) let hals. A similar dorsal-to-ventral transformation is observed in Pc Dlw /Dlw clones. Dlw(1)/Dlw(2) clones have no effect elsewhere, except in the dorsal notum, which may differentiate extra macrochaetes. We propo se that: (1) Dlw(+) is required for the specification of dorsal compar tment; (2) some genes of the Polycomb group act as negative regulators of Dlw(+), while some genes of the trithorax group act as positive re gulators.