Physiological and molecular biological studies on acquisition of auditory responsiveness in zebrafish

在活体内研究了斑马鱼胚胎和仔鱼内耳毛细胞的发育起源、耳石大小对听觉敏感性的影响以及后脑神经元放电特性发育变化的分子机制。我们首先证明，系留细胞是胚胎内耳中与耳石(耳石)相关的少数纤毛细胞，在形态和功能上分化为第一毛细胞。其次，含有大耳石的球囊内耳器官是探测声音所必需的，而含有小耳石的椭圆形内耳器官则不是。但是，通过实验扩大耳石的椭圆形毛细胞获得了声音的感觉，这表明耳石的大小对感觉声音至关重要。第三，在接受听神经输入的后脑网状脊髓神经元中，Mauthner细胞的独特放电特性是在早期发育过程中获得的，它们需要Kvβ亚基和低阈值KV1亚基的共同表达。

The developmental origin of inner ear hair cells, role of ear stone size on acoustic sensitivity and molecular mechanisms underlying developmental change in firing properties of hindbrain neurons were studied in vivo in zebrafish embryos and larvae. We demonstrated first that tether cells, a few ciliated cells associated with an ear stone (otolith) in the embryonic inner ear, morphologically and functionally differentiate into first hair cells. Second, the saccule inner ear organ containing a large otolith is necessary to detect sound, whereas the utricle containing a small otolith is not. But, utricle hair cells with experimentally enlarged otoliths acquired the sense of sound, suggesting that otolith size is crucial to sense sound. Third, unique firing properties of Mauthner cells among the hindbrain reticulospinal neurons receiving auditory nerve inputs are acquired during early development and coexpression of Kv beta subunits with low-threshold Kv1 subunits is required for them.