Figure 7
Tm[Tmc2] expression does not disrupt auditory function in Tmc2Δ/Δ mice but fails to rescue auditory function in Tmc1Δ/Δ mice. Recordings were performed from 8 Tm[Tmc2];Tmc2Δ/Δ (red), 7 Tmc2Δ/Δ (without Tm[Tmc2], black) littermates, and 8 Tm[Tmc2];Tmc1Δ/Δ mice (blue). (A) Similar, sensitive, distortion product otoacoustic emission (DPOAE) audiograms (2f1-f2 DPOAE magnitude as function of f2 frequency, mean ± S.D.) recorded from Tm[Tmc2];Tmc2Δ/Δ and Tmc2Δ/Δ mice. No DPOAEs were recorded above the noise floor (0 dB SPL) from Tm[Tmc2];Tmc1Δ/Δ mice. DPOAEs were recorded from the auditory meatus. F1 was set at 70 dB SPL and f2 was set at 60 dB SPL. (B) Similar, sensitive, compound action potential (CAP recorded from the round window) audiograms (CAP threshold as a function of stimulus frequency, mean ± S.D.) were recorded from Tm[Tmc2];Tmc2Δ/Δ and Tmc2Δ/Δ, but not from Tm[Tmc2];Tmc1Δ/Δ mice as indicated by the blue line (upper SPL of sound system). (C) Cochlear microphonic potential (CM) as a function of the level of the 5 kHz stimulus tone (mean ± S.D.) recorded from the round window are almost identical in Tm[Tmc2];Tmc2Δ/Δ and Tmc2Δ/Δ mice. CM was not elicited from Tm[Tmc2];Tmc1Δ/Δ mice for any level of the 5 kHz tones. (D) Threshold, mechanical frequency tuning curves, based on 0.2 nm displacements recorded from the basilar membrane in cochlear basal turns are almost identical in Tm[Tmc2];Tmc2Δ/Δ and Tmc2Δ/Δ mice. Tuning curves measured from Tm[Tmc2];Tmc1Δ/Δ mice resemble post-mortem responses from Tm[Tmc2];Tmc2Δ/Δ and Tmc2Δ/Δ, mice. Measurements were confined to mice aged P20–28.
