Atypical tuning and amplification mechanisms in gecko auditory hair cells.

SignificanceGeckos are lizards capable of vocalization and can detect frequencies up to 5 kHz, but the mechanism of frequency discrimination is incompletely understood. The gecko's auditory papilla has a unique arrangement over the high-frequency zone, with rows of mechanically sensitive hair bundles covered with gelatinous sallets. Lower-frequency hair cells are tuned by an electrical resonance employing Ca2+-activated K+ channels, but hair cells tuned above 1 kHz probably rely on a mechanical resonance of the sallets. The resonance may be boosted by an electromotile force from hair bundles found to be evoked by changes in hair cell membrane potential. This unusual mechanism operates independently of mechanotransduction and differs from mammals which amplify the mechanical input using the motor protein prestin.