THE MAXILLARY PALP OF DROSOPHILA - ULTRASTRUCTURE AND PHYSIOLOGY DEPENDS ON THE LOZENGE GENE

The ultrastructure and physiology of the maxillary palp of Drosophila melanogaster have been studied in wild-type and lozenge mutants. Olfac tory physiology in the maxillary palp is shown to depend upon the loze nge(lz) gene. Reduced response amplitudes were recorded for all odoran ts tested, and the physiological defect was shown to map to the it loc us. The structure of the maxillary palp sensilla is described by scann ing electron microscopy (SEM) at high magnification, initially in the wild-type. A linear arrangement of pores, connected by furrows, was fo und in one class of sensilla, the basiconic sensilla. In the lz(3) mut ant, morphological alterations in the basiconic sensilla and duplicati ons of sensilla are documented by SEM. The correlation of structural a bnormalities in the lz sensilla and physiological abnormalities in odo rant response are consistent with an olfactory role for the basiconic sensilla of the maxillary palp.