We are combining genetics with behavioral, electrophysiological and cell biological methods to dissect auditory molecular mechanisms, using Drosophila as a model organism. The Drosophila male, when courting a female, vibrates one wing to sing the ‘love song’. The female and male both hear the love song with their antennae and respond in a sex-specific manner. We have recovered several auditory mutants that represent genes involved in different molecular processes essential in hearing or responding normally to the love song. One of these mutants, beethoven, disrupts the normal neuronal electrophysiology of Johnston's organ, the ciliated mechanoreceptive organ in the antenna responsible for hearing. Identifying the gene product of beethoven and other such genes and examining their functional roles in hearing will provide new insights into auditory molecular mechanisms, not only in Drosophila, but perhaps in humans as well. Another goal is to further understand how organisms decipher the meaning in auditory information, and how different individuals, for example males and females, can respond differently to the same sounds. Thus we want to elucidate the neuronal circuitry by which sensory firing patterns are decoded in the brain (figure). Genetically engineered Drosophila strains that express marker genes in specific subsets of neurons will facilitate this approach. For example, we can express a GFP-tagged n-synaptobrevin molecule in the auditory neurons to visualize their projections into the brain. In our auditory mutant collection, we expect to find disruptions in genes required for the normal development of neurons in the auditory circuit, or disruptions in genes required for these neurons to function properly in a sexually dimorphic manner.