ANALYSIS OF THE ANTENNAL PHENOTYPE IN THE DROSOPHILA MUTANT LOZENGE

Previous work on the lozenge (lz) gene complex of D. melanogaster has focused on the compound eye. Hem we study the effects of 22 lz mutatio ns on the antennal sensilla. The antenna of strong lz alleles is chara cterized by a lack of basiconic sensilla and by a significantly increa sed density of coeloconic sensilla. Intermediate alleles have few basi conic sensilla, they exhibit a highly increased density of trichoid se nsilla, but a normal coeloconic density. Basiconic sensilla on the max illary palps are weakly affected even by strong lz alleles. The antenn al phenotype for most of the strong and intermediate mutants is partia lly dominant over wild type. Although this complicates the interpretat ion of complementation data, 12 selected mutants that were studied in heteroallelic combinations seem to define a single cistron. Temperatur e shifts of the e allele showed that gene activity is crucial from abo ut 87% of the third larval instar up to 7% of pupal life. Applying res trictive temperature early during this period results in a 'novel' phe notype that is characterized by a dramatic decrease in the density of trichoid sensilla, whereas a late pulse of restrictive temperature lea ds to a 'normal' intermediate phenotype. Our data suggest that the lz gene controls at least five different functions in the antenna: the si ze of the third antennal segment, the overall number and density of se nsilla, the proportions of the 3 types of sensilla, and the generation of basiconic sensilla.