Figure 5. Analysis of mechanotransduction in Tomt mutants.

(A–D) P5 explants from middle region of the cochlea cultured for 24 hr with or without 1 mM Gentamicin, followed by fixation and immunostaining for MYO7A. (A) Tomt^del/+ cultured without Gentamicin. (B) Tomt^del/+ cultured for 24 hr with 1 mM Gentamicin. Note the almost complete loss of hair cells. (C) Tomt^del/del cultured for 24 hr with 1 mM Gentamicin. Hair cells are spared from Gentamicin-mediated ototoxicity. (D) Tomt^add/add cultured for 24 hr with 1 mM Gentamicin. Hair cells are spared from Gentamicin-mediated ototoxicity. (E) Representative mechanotransduction currents in OHCs from Tomt^add/+ and Tomt^add/add mice at P7 in response to a set of 10 ms hair bundle deflections ranging from −400 nm to 1000 nm (100 nm steps). (F) Current displacement plot obtained from similar data as shown in (E). Data are mean ± SEM. (G) Summary of data obtained from experiments as shown in (E–F) for Tomt^add/+ and Tomt^add/add at P4 and P7. Data are plotted as maximum MET currents. Number of cells tested is indicated on each column of the graph. Scale bar in (B) = 5 µm and applies to (A–D).

DOI: http://dx.doi.org/10.7554/eLife.24318.007

Figure 5—figure supplement 1. Basic membrane properties of cochlear hair cells in Tomt mutants.

(A) Membrane potential (in millivolts (mV)) of outer hair cells from P6 Tomt^add/+ and Tomt^add/add mice current-clamped at 0 picoamps. Number of cells is indicated on individual columns of the graph. (B) Outward currents (in nanoamps (nA)) elicited from outer hair cells of P6 Tomt^add/+ and Tomt^add/add mice at command potentials from −90 mV to 60 mV with a holding potential of −70 mV. (C). Nonlinear capacitance (in picofarads (pF)) as a function of voltage of outer hair cells from P16 Tomt^add/+ and Tomt^add/add mice. At right are summary data showing the membrane potential at which the peak Cm was recorded and the absolute value of the peak Cm, in pF. Data are mean ± SEM.

DOI: http://dx.doi.org/10.7554/eLife.24318.008