Analysis Tools
hearing/vestibular/ear
|
• at >P0, severe abnormalities are noted throughout the cochlea (base, middle, and apex), affecting both IHC and OHC hair bundle development
• early postnatal AAV2/8-mediated delivery of clarin-1 into the inner ears does not prevent or correct the misshaping of hair bundles; both IHC and OHC hair bundles show altered shape and a loss of short-row stereocilia between P25 and P30
|
|
• at P12, the short row of stereocilia has almost entirely regressed in IHCs
|
|
• at >P0, OHC hair bundles exhibit a linear, wavy and/or hooked form and are occasionally fragmented into 2 or 3 clumps of stereocilia
• at P12, the short row of stereocilia has almost entirely regressed in OHCs
• at P12, F-actin staining of the cuticular plate on the apical surface is irregular, with furrows corresponding to regions of clumped stereocilia
|
|
• at P28, TEM analysis revealed an abnormal swelling of IHC afferent terminals along with an abnormal distribution of postsynaptic AMPA glutamate receptors
|
|
• at P18, the Ca2+ current density in IHCs is almost twice that in control mice
• analysis of the voltage-dependent activation of Ca2+ currents revealed a negative shift of 7 mV at P9 and P13 and a significantly less steep activation curve at P18
• at >P9, the kinetics of Ca2+ current activation at negative membrane potentials are slower than in control mice; moreover, time-dependent inactivation of IHC Ca2+ currents is greater than in control mice at P13 and P18
• intracochlear AAV2/8-mediated delivery of clarin-1 restores synapse ribbon structure and function, leading to normal Ca2+ currents, kinetics, and Ca2+ efficiency of exocytosis
|
|
• starting at P15, ABR thresholds are significantly high over the entire 5- to 40-kHz frequency range at a sound pressure level (SPL) exceeding 90 dB versus only 20-40 dB in control mice
• intracochlear AAV2/8-mediated delivery of clarin-1 leads to moderate hearing preservation; a decrease of ~10-15 dB in ABR thresholds relative to untreated ears is observed at 3 weeks after injection
|
|
• at P20, no significant electrically evoked brainstem responses (EEBRs) are recorded in the cochleae after direct stimulation of primary auditory neurons, indicating a strong electrical conduction defect; EEBR wave II (EII) and later waves (EIII and EIV), corresponding to responses of higher auditory centers, are absent
|
|
• DPOAEs are undetectable as early as P15
|
nervous system
|
• Ca2+ efficiency for IHC exocytosis is normal at P9 but significantly lower than that in control mice at P13
• intracochlear AAV2/8-mediated delivery of clarin-1 results in normal Ca2+ efficiency of exocytosis
|
|
• at >P0, severe abnormalities are noted throughout the cochlea (base, middle, and apex), affecting both IHC and OHC hair bundle development
• early postnatal AAV2/8-mediated delivery of clarin-1 into the inner ears does not prevent or correct the misshaping of hair bundles; both IHC and OHC hair bundles show altered shape and a loss of short-row stereocilia between P25 and P30
|
|
• at P12, the short row of stereocilia has almost entirely regressed in IHCs
|
|
• at >P0, OHC hair bundles exhibit a linear, wavy and/or hooked form and are occasionally fragmented into 2 or 3 clumps of stereocilia
• at P12, the short row of stereocilia has almost entirely regressed in OHCs
• at P12, F-actin staining of the cuticular plate on the apical surface is irregular, with furrows corresponding to regions of clumped stereocilia
|
|
• at P28, TEM analysis revealed an abnormal swelling of IHC afferent terminals along with an abnormal distribution of postsynaptic AMPA glutamate receptors
|
|
• at P18, the Ca2+ current density in IHCs is almost twice that in control mice
• analysis of the voltage-dependent activation of Ca2+ currents revealed a negative shift of 7 mV at P9 and P13 and a significantly less steep activation curve at P18
• at >P9, the kinetics of Ca2+ current activation at negative membrane potentials are slower than in control mice; moreover, time-dependent inactivation of IHC Ca2+ currents is greater than in control mice at P13 and P18
• intracochlear AAV2/8-mediated delivery of clarin-1 restores synapse ribbon structure and function, leading to normal Ca2+ currents, kinetics, and Ca2+ efficiency of exocytosis
|
|
• at P20, no significant electrically evoked brainstem responses (EEBRs) are recorded in the cochleae after direct stimulation of primary auditory neurons, indicating a strong electrical conduction defect; EEBR wave II (EII) and later waves (EIII and EIV), corresponding to responses of higher auditory centers, are absent
|
|
• mice exhibit an IHC synaptopathy characterized by a much weaker downregulation of Ca2+ currents than normally observed at the onset of hearing; a hyperpolarized voltage-activation curve and an extended calcium-dependent inactivation of Ca2+ currents; and an intrinsic defect of the exocytotic machinery
|
|
• at P15, IHCs exhibit numerous round (immature) ribbons and persistence of axosomatic efferent synaptic contacts, suggesting that synaptic ribbon maturation is delayed; only 60% of the ribbons display a mature plate-like shape
• the fraction of IHC immature ribbons decreases from 40% at P15 to less than 20% at P28, thereby reaching near-normal values
• at P13, CaV1.3 channels form larger patches in the synaptic active zone of IHCs and the ribbons are much smaller than in control mice
• the rate of colocalization for CaV1.3- and ribeye-immunoreactive areas is normal at P9, but significantly lower than that in control IHCs at P13, suggesting a loose spatial coupling between Ca2+ channels and the synaptic machinery
• at P9 and P13, the F-actin cortical network is disrupted at the IHC ribbon synapse
• intracochlear AAV2/8-mediated delivery of clarin-1 results in normal synapse ribbon structure with tight clustering of Ca2+ channels in the IHC active zone at P15-P18
|
|
• significant loss of parvalbumin-positive spiral ganglion neurons within Rosenthal's canal at P24-P30
|
|
• cochlear immunostaining with Neurofilament 200 (NF200) revealed a significant loss of auditory nerve fibers at P25
|
cellular
|
• Ca2+ efficiency for IHC exocytosis is normal at P9 but significantly lower than that in control mice at P13
• intracochlear AAV2/8-mediated delivery of clarin-1 results in normal Ca2+ efficiency of exocytosis
|
