OLFACTORY PHYSIOLOGY IN THE DROSOPHILA MAXILLARY PALP REQUIRES THE VISUAL-SYSTEM GENE RDGB

We describe the kinetics of odorant response in the maxillary palp of Drosophila, and show that the rate of recovery from odorant stimulatio n is affected by mutation of the rdgB (retinal degeneration B) gene. W e use immunocytochemistry to confirm that the rdgB gene product is exp ressed in the maxillary palp. rdgB has recently been shown to encode a protein with Ca2+-binding sites and sequence similarity to rat brain phosphatidylinositol transfer protein; it is located near the rhabdome ric membranes in photoreceptor cells, where it has been suggested to p lay a role in membrane transport. The delay in recovery kinetics that we observe in olfactory tissue may reflect a defect in membrane restor ation at the conclusion of the olfactory transduction cascade. The use of common molecules in the physiology of two olfactory organs, and in both visual and olfactory physiology, is discussed.