Functional analysis of zebrafish retina-specific atonal gene and its expression profile

在脊椎动物中，视网膜区域特定于前神经板并外翻形成视杯，在视杯中分化出六种主要的神经元和一种类型的胶质细胞。因此，视网膜提供了一个很好的模型，在其中研究发育中的大脑中的神经元分化。另一个有趣的特征是，神经元分化在一个位置开始，然后扩散到整个视网膜区域。在无脊椎动物果蝇的复眼中，分泌因子Hedgehog和转录因子无调性之间的循环对于神经源性波在眼场中的发展是必不可少的。然而，脊椎动物视网膜神经发生的诱导和进展的机制尚不清楚。为了阐明发育中的视网膜神经元分化的诱导和进展的机制，我们克隆了斑马鱼无性基因ath5，该基因仅在新分化的视网膜神经…中表达在斑马鱼中，更多的是在鼻侧视网膜开始表达，并扩散到视网膜的背侧和颞区，这表明斑马鱼的神经元分化浪潮从鼻侧扩散到颞区。鼻区毗邻视柄组织，这增加了视柄和神经视网膜之间的相互作用对于鼻部视网膜最初诱导ath5表达的重要性的可能性。为了测试这种可能性，用聚焦的激光束消融了视柄和神经视网膜之间的边界。这种消融扰乱了最初对ath5表达的诱导。此外，视柄组织移植在视网膜的颞区异位诱导了AT5的表达。这些数据表明，神经发生的最初诱导是由视柄信号调节的，而进展过程是由短程信号的继而介导的。这些数据表明，脊椎动物和果蝇的眼睛对神经源性波的调节有惊人的相似之处。较少

In the vertebrate, the retina region is specified in anterior neural plate and evaginates to form the optic cup, where six major classes of neurons and one-type of glia differentiate. Thus, the retina provides a good model, in which to study neuronal differentiation in the developing brain. Another interesting feature is that neuronal differentiation is initiated in one location and spreads to the whole region of the retina. In the compound eye of the invertebrate, the fruit fly, Drosophila melanogaster, cycle between activation of secretion factor, Hedgehog, and transcription factor, Atonal, is essential for progression of a neurogenic wave across the eye field. However, mechanisms underlying induction and progression of neurogenesis in the vertebrate retina is unknown.To elucidate mechanisms underlying induction and progression of neuronal differentiation in the developing retina, we cloned zebrafish atonal gene, ath5, which expresses exclusively in newly differentiating retinal neur … More ons, In zebrafish, ath5 expression is initiated at nasal retina and spreads to dorsal and temporal region of the retina, suggesting that a wave of neuronal differentiation spreads from nasal to temporal in zebrafish. The nasal region is adjacent to the optic stalk tissue, raising a possibility that interaction between optic stalk and neural retina is important for initial induction of ath5 expression in the nasal retina. To test this possibility, the boundary between the optic stalk and the neural retina was ablated with focussed laser beam. This ablation disrupts initial induction of ath5 expression. Furthermore, transplantation of optic stalk tissue induces ectopically ath5 expression in temporal region of the retina. These data suggest that initial induction of neurogenesis is regulated by signals from optic stalk and that progression process is mediated by relays of short-range signals. These data suggest a striking similarity of regulation of a neurogenic wave between the vertebrate and Drosophila eye. Less