An Age-Related Hearing Protection Locus on Chromosome 16 of BXD Strain Mice
(a) 16 kHz ABR testing of a good-hearing BXD79 mouse revealed measurable responses to sound as low as 10 dB (bottomed greenline) and a deaf BXD187 mouse had no response to 100 dB (the top green line); both mice are at the age of 21 months. (b) ABR thresholds of parental 3-month-old D2 mice, 12-month-old B6 mice, and 24-month-old BXD79 mice that have the best hearing among the 54 examined BXD strains. (c) H&E stained cross-sections of the inner ears from a deaf mouse (BXD125) (C1-3) and a good hearing mouse (BXD155) (C1-3). Morphological contrast of the whole cochleae from the deaf BXD125 (C1) and the good hearing BXD155 (C1) strain. OHCs and IHCs are lost in the deaf ear (C2) but are present in the good ear (C2). Spiral ganglion (SG) cells are lost in the deaf ear (C3) but are present in the good ear (C3).. The corrected densities of the SGNs () in the basal cochlear turn in deaf BXD mice () are significantly less than those of good hearing BXD mice () (; by -test). No significant differences in the mean density of the SGNs in the apical cochlear turns were observed (data not shown). (d) ABR thresholds of deaf BXD125 and good-hearing BXD155 mice are exemplified at 1 year old (). Error bars indicate the standard deviation from the SEM. The ABR thresholds are significantly different between the two strains ( by ANOVA test).
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