Auditory transduction in Müller’s organ of the locust

Insect acoustic receivers take many forms, and have few anatomical similarities to vertebrate ears, but convergent evolution has clearly led to common principles of operation. For instance, the gating-spring model describes the biophysics of both vertebrate hair cells and the antennal sound-receiver of Drosophila. The genetic workhorse, Drosophila, has been used to identify potential mechanotransduction ion channels and provided hypotheses about the mechanisms of mechanotransduction, but the auditory neurons of these small flies have stubbornly resisted all attempts to record their intracellular electrical properties. Without recording the current flowing through the auditory mechanotransduction ion channel in vivo, it is difficult to confirm its identity. Current models of insect auditory transduction fall into two camps, depending on whether NompC or Nanchung-Inactive (both transient receptor potential ‘TRP’ channels) is considered to be the likely mechanotransduction ion channel. To resolve the identity of the mechanotransduction ion channel we isolated the mechanotransduction current through whole-cell patch-clamp recordings from the auditory neurons of the desert locust Schistocerca gregaria. Application of the insecticide, pymetrozine, a specific agonist for the Nanchung-Inactive ion channel, elicited a depolarising current that matched the maximal sound-evoked current. Our findings support the proposal that Nanchung-Inactive is the mechanotransduction ion channel in the auditory neurons of the desert locust.