Rhodes Charlotte R, Parkinson Nicholas, Tsai Hsun, Brooker Debra, Mansell Siobhan, Spurr Nigel, Hunter A Jackie, Steel Karen P, Brown Steve D M
MRC Institute of Hearing Research, University Park, Nottingham, NG7 2RD, UK.
J Neurocytol. 2003 Nov;32(9):1143-54. doi: 10.1023/B:NEUR.0000021908.98337.91.
The semi-dominantly inherited mouse mutation pardon (Pdo) was isolated due to the lack of a Preyer reflex (ear flick) in response to sound from a large-scale N -ethyl- N -nitrosourea (ENU) mutagenesis programme. Dissection of the middle ear revealed malformations in all three ossicles, rendering the ossicular chain incomplete. Hair cell counts in the apical turn of the organ of Corti revealed a significant 22.7% increase in the number of outer hair cells. Raised compound action potential thresholds in Pdo/+ mutants suggested a combined sensorineural/conductive hearing loss. We show that a missense mutation in the homeobox gene Emx2 is responsible for these defects, identifying a new function for this gene in the development of specific structures in the ear.
半显性遗传的小鼠突变体“赦免”（Pdo）是在一项大规模N-乙基-N-亚硝基脲（ENU）诱变计划中，由于缺乏对声音的普雷耶反射（耳部轻弹）而分离出来的。中耳解剖显示所有三块听小骨均有畸形，导致听骨链不完整。柯蒂氏器顶转的毛细胞计数显示，外毛细胞数量显著增加了22.7%。Pdo/+突变体中复合动作电位阈值升高表明存在感音神经性/传导性混合性听力损失。我们发现，同源盒基因Emx2中的一个错义突变是这些缺陷的原因，从而确定了该基因在耳部特定结构发育中的新功能。
