9407887 Dubin ABSTRACT The major aim of this research is to identify mechanisms underlying olfactory transduction in receptor neurons of a simple animal (Drosophila melanogaster) with the long-term goal of understanding how odorant-induced changes in cellular excitability encode information which can be processed by higher order cells. The proposed experiments will combine for the first time the genetic variability of Drosophila melanogaster with whole cell and single channel electrophysiological analyses to study odorant-modulated ion channel function and cellular excitability in wild type flies. The molecular nature of these modulated conductances and second messenger pathways will be investigated using mutants with known defects in genes encoding ion channels and enzymes involved in signal transduction processes. Furthermore, a number of mutants defective in olfaction derived from enhancer trap lines with predominant olfactory neuron staining will be studied at the receptor cell level to examine the physiological site of the defects.