Fig. 8

Hearing disability in S2-SP1 zebrafish at 120hpf.

M-cells was recorded under sound stimulation (500 Hz, 10 ms). (A) Examples of the recorded EPSC in wild-type (WT), S2-SP1 konckdown, Mcon and rescued individuals. The sound stimuli (80 dB) lasted 10 ms, during which hair cell signals could be induced several times so that a single M-cell could receive input from many different hair cells through ganglion cells because multiple action potentials in the ganglion cells could be produced., As a result, multiple peaks were produced and the EPSC amplitudes were shown for different sound levels. (B) Average C-startle response probability. For each group, 50 larvae were tested. Sound intensities are designated with + and ++ because sound was applied using different units in the M-cell recording and startle response experiments. ***P<0.001. (C) Examples of C-shaped startle responses of different larvae types in response to 500 Hz frequency, 10 ms duration. WT and Mcon-MO larvae usually swam or rested with their backs facing upward, and they tended to swim at one depth. The typical escape response of WT larva was initiated 5–11 ms after sound stimulation, However, S2-SP1 larvae usually remained stationary and rested in abnormal positions. They swam up and down or in circles. Abnormal swimming behaviour of S2-SP1 knockdown zebrafish indicated defective balance. Some S2-SP1 larvae had no response to outside sound stimulation. After rescue, S2-SP1 zebrafish regained their hearing.