PATTERNING OF DORSAL RETINA

视网膜的图案化及其轴突输出对视觉功能至关重要，而视网膜顶盖投射- 剖分是发展二维神经映射的经典模型。视网膜神经节细胞获得性 沿背腹(D-V)和前后(A-P)轴的位置坐标，然后将这些 到轴突引导分子的分级表达，它控制视束中的地形分类和 顶盖上的地形目标。从长远来看，我们试图了解轴突Beha的梯度是如何- VIOR被生成。作为第一步，我们建议在这里全面分析参与 背部视网膜的图案，到目前为止还知之甚少。 鸡和非洲爪哇的错误表达和显性阴性实验表明，BMP4、Tbx5、 背侧规范和D-V地形图中的ePhin-B2。然而，Tbx5和ePhin-B2的作用是 没有被功能丧失分析测试，我们的数据表明肯定有更多的基因参与其中。我们会 使用斑马鱼视觉系统分析D-V视网膜图案，这是快速和精确损失的理想选择- 用于研究视网膜花纹和视网膜顶盖地形图的功能实验。主要目标是：(1) 测试已知的候选基因Bmp4、tbx5和ewitin-B2在指定背侧视网膜中所需的作用 命运和地形预测；(2)测试我们已经确定的新候选基因的作用，具体如下： Cally Tcf7、其他tbx基因和eaffin-B1，以及(3)利用正向遗传筛查确定新基因 破坏视网膜背部规范的突变体。我们的初步数据首次涉及Wnt信号 在D-V视网膜模式中，并进一步提示Wnt和BMP通路之间的串扰。 在我们之前在斑马鱼视觉系统方面的专业知识的基础上，我们将结合遗传实验 利用斑马鱼的快速和复杂的胚胎学和表型分析。我们将使用ex- 列出突变体和反义吗啉寡核苷酸，以及通过正向基因分离的新突变体。 抽动和反向遗传(耕作)遗传筛选。我们将严格测试现有的D-V视网膜模型 模式，并通过测试从我们的初步数据产生的新假设，以及通过 对所需基因进行无偏见筛选。这些研究将解决以下两个基本问题 发育神经生物学：神经系统的区域如何获得位置坐标？和, 那么，它们如何在地形上相互连接呢？识别视网膜背部的关键基因 将为这些基因如何相互作用以产生地形梯度的未来工作奠定基础。 与公共卫生的相关性。视觉系统的发展和结构都得到了显著的保存。 ED跨越了从鱼类到人类的进化。因此，这些研究将阐明人眼是如何 形成并形成图案。这一点特别令人感兴趣，因为眼球背腹图案的缺陷 与人类发育障碍有关，如缺陷症。

The patterning of the retina and its axonal output are critical for visual function, and the retinotectal proj- ection is a classic model of the development of two-dimensional neural maps. Retinal ganglion cells acquire positional coordinates along the dorsal-ventral (D-V) and anterior-posterior (A-P) axes, then translate these into graded expression of axon guidance molecules, which control topographic sorting in the optic tract and topographic targeting on the tectum. In the long term, we seek to understand how gradients of axonal beha- vior are generated. As a first step, we propose here a comprehensive analysis of the genes involved in the patterning of dorsal retina, which to date is poorly understood. Misexpression and dominant-negative experiments in chick and Xenopus have implicated BMP4, Tbx5, and ephrin-B2 in dorsal specification and D-V topography. However, the roles of Tbx5 and ephrin-B2 have not been tested by loss-of-function analysis, and our data show that more genes must be involved. We will analyze D-V retinal patterning using the zebrafish visual system, which is ideal for rapid and precise loss- of-function experiments to study retinal patterning and retinotectal topography. The main goals are: (1) to test the required roles of the known candidate genes bmp4, tbx5, and ephrin-B2 in specifying dorsal retinal fate and topographic projections; (2) to test the roles of new candidate genes we have identified, specifi- cally tcf7, other tbx genes, and ephrin-B1\ and (3) to identify new genes with a forward-genetic screen for mutants that disrupt dorsal retinal specification. Our preliminary data implicate Wnt signaling for the first time in D-V retinal patterning, and furthermore suggest crosstalk between the Wnt and BMP pathways. Building on our previous expertise in the zebrafish visual system, we will combine genetic experiments with the rapid and sophisticated embryological and phenotypic analysis possible in zebrafish. We will use ex- isting mutants and antisense morpholino oligonucleotides, as well as new mutants isolated by forward gene- tic and reverse genetic (TILLing) genetic screens. We will critically test the existing model of D-V retinal patterning, and extend it significantly by testing new hypotheses arising from our preliminary data, and by conducting an unbiased screen for required genes. These studies will address two fundamental questions in developmental neurobiology: How do regions of the nervous system acquire positional coordinates? and, How do they then make topographic connections with each other? Identifying the key genes in dorsal retina will lay the groundwork for future work on how these genes interact to generate topographic gradients. Relevance to public health. The development and structure of the visual system are remarkably conserv- ed across evolution from fish to humans. Therefore, these studies will shed light on how the human eye is formed and becomes patterned. This is of particular interest because defects in dorsoventral eye patterning are associated with human developmental disorders such as coloboma.