Role of Bar locus in development of legs and antenna in Drosophila melanogaster

Abstract

The X-linked Bar (B) mutation of Drosophila melanogaster, responsible for the well-known Bar eye phenotype due to over-expression of the BarH1 homeodomain protein, is shown to enhance the abnormalities in legs and antennae of flies carrying a viable combination of certain decapentaplegic (dpp) loss of function mutant alleles. It is also shown that the homeo-domain carrying BarH1/BarH2 protein products of the B locus are expressed in a characteristic annular pattern in areas of normal larval leg and antennal discs that correspond to the distal regions of adult fly appendages. dpp-mutant background partly disrupts the expression pattern of Bar homeo-proteins in these discs and a combination of B and dpp-mutant alleles disrupts the Bar expression patterns in these imaginal discs much more severely. This is in agreement with the more severe phenotypes of legs and antennae of such flies. We suggest that the homeo-box containing B genes function as new members of the proximal distal sector genes and are important for patterning these appendages along their proximo-distal axes.