Distinct mechanisms of action of the Lozenge locus in Drosophila eye and antennal development are suggested by the analysis of dominant enhancers.

The development of the olfactory sense organs on the antenna of the fruit fly Drosophila utilises mechanisms distinct from those used in the rest of the adult peripheral nervous system. Lozenge (lz) is the only locus hither-to identified as required for the development of antennal sense organs. In addition to effects on the antenna, mutations in lz also affect the development of the eye and maxillary palp. We have used the readily-scored eye-phenotype in a temperature sensitive lz allele to screen for dominant modifiers of phenotypes at this locus. We analyse the phenotypes of both intragenic and extragenic modifiers. Our results reinforce the view from developmental studies that lz functions in eye and antennal development in distinct ways.