Characterization of transduction in Drosophila mechanosensory bristles has revealed striking similarities to vertebrate hair cells. The presence of developmental-pathway parallels and expression of related proteins performing similar functions in both sensory systems implies that discovery of new fly mechanosensory proteins will foster our understanding of mechanotransduction in mammals. This knowledge will facilitate design and development of treatments for hearing loss and deafness, which afflict nearly 30 million Americans. The appeal of Drosophila as a model organism for studying mechanotransduction arises from its panoply of genetic tools, as well as the ability to record from mechanosensory bristles. A large-scale screen for fly mechanosensory mutants has rewarded scientists with the identity of two key mechanosensory proteins: a transduction channel and a mechanical linkage between the sensory neuron and overlying bristle. Two additional mutants isolated in the screen have physiological properties similar to the transduction channel mutant, thus they likely possess mutations in components of the transduction apparatus. The thrust of this study is to characterize these mutants. Mutated genes will be mapped and sequenced, then expression patterns of genes will be determined using in situ hybridization. Finally, to analyze the function of mechanosensory proteins, a method will be developed to express modified proteins specifically in fly mechanosensory neurons.