GENETIC DISSECTION OF MECHANOSENSORY TRANSDUCTION - MECHANORECEPTION-DEFECTIVE MUTATIONS OF DROSOPHILA

To identify genes involved in mechanotransduction, Drosophila larvae w ere screened for X-linked mutations affecting a behavioral response to touch. Many mutations that caused nondevelopmental defects were recov ered, among them multiple alleles of the genes uncoordinated (unc) and uncoordinated-like (uncl). Adult flies mutant in these genes showed r educed viability that was associated with behavioral phenotypes rangin g from reduced locomotor activity to total uncoordination, Behavioral analysis of mosaic flies indicated that external sensory bristles are a focus of the unc mutant defect. Extracellular recordings from mutant mechanosensory bristles revealed that mechanoreceptor potentials were absent or reduced in both unc and uncl mutants. A second genetic scre en, for unc-like uncoordination, yielded mutations in seven genes on t he second chromosome; mutations in five of these genes also reduced or eliminated bristle mechanoreceptor potentials. These mutants provide the basis for a genetic, electrophysiological, and molecular dissectio n of mechanotransduction.