NompC TRP Channel Is Essential for Drosophila Sound Receptor Function

The idea that the NompC TRPN1 channel is the Drosophila transducer for hearing has been challenged by remnant sound-evoked nerve potentials in nompC nulls [1-5]. We now report that NompC is essential for the function of Drosophila sound receptors and that the remnant nerve potentials of nompC mutants are contributed by gravity/wind receptor cells. Ablating the sound receptors reduces the amplitude and sensitivity of sound-evoked nerve responses, and the same effects ensued from mutations in nompC. Ablating the sound receptors also suffices to abolish mechanical amplification, which arises from active receptor motility [6, 7], is linked to transduction [8], and also requires NompC [9]. Calcium imaging shows that the remnant nerve potentials in nompC mutants are associated with the activity of gravity/wind receptors and that the sound receptors of the mutants fail to respond to sound. Hence, Drosophila sound receptors require NompC for mechanical signal detection and amplification, demonstrating the importance of this transient receptor potential channel for hearing and reviving the idea that the fly's auditory transducer might be NompC.