Bristle multiplication phenotype, ectopic bristles are complete sensory organs. Anterior orbital, ocellar and posterior supra-alar bristle loss due to defects in the cell fate specification in the bristle lineage.
Brd1 homozygotes survive and exhibit more severe phenotypes than heterozygotes. Brd1/+ = Brd1 hemizygous with Brd-. Brd1 strongly affects macrochaetae and other imaginal-disc sensilla (i.e., trichoid, campaniform, basiconic), but only mildly increases microchaete density. In addition to sensillum multiplication, Brd1 homozygotes also exhibit bristle loss, with anterior orbitals absent (>90%) and a less frequent loss of ocellar macrochaetae (<5%).The EMS-induced point revertants of Brd1 tested (Brdrv1 to Brdrv4) are homozygous viable, viable in trans to Brd deficiencies and display no mutant phenotypes in either situation.