The Voltage-Gated Potassium Channel <i>Shal</i> (K _v 4) Contributes to Active Hearing in <i>Drosophila</i>

The full complement of ion channels which influence insect auditory mechanotransduction and the mechanisms by which their influence is exerted remain unclear. <i>Shal</i> (K_v4), a <i>Shaker</i> family member encoding voltage-gated potassium channels in <i>Drosophila melanogaster</i>, has been shown to localize to dendrites in some neuron types, suggesting the potential role of <i>Shal</i> in <i>Drosophila</i> hearing, including mechanotransduction. A GFP trap was used to visualize the localization of the <i>Shal</i> channel in Johnston's organ neurons responsible for hearing in the antenna. <i>Shal</i> protein was localized strongly to the cell body and inner dendritic segment of sensory neurons. It was also detectable in the sensory cilium, suggesting its involvement not only in general auditory function but specifically in mechanotransduction. Electrophysiological recordings to assess neural responses to auditory stimuli in mutant <i>Shal</i> flies revealed significant decreases in auditory responses. Laser Doppler vibrometer recordings indicated abnormal antennal free fluctuation frequencies in mutant lines, indicating an effect on active antennal tuning, and thus active transduction mechanisms. This suggests that <i>Shal</i> participates in coordinating energy-dependent antennal movements in <i>Drosophila</i> that are essential for tuning the antenna to courtship song frequencies.