Genetic and molecular anlaysis of neural development

描述（由申请人提供）：脊椎动物神经系统内细胞类型的多样性取决于发生在发育早期阶段的模式事件。神经组织的形态和形态与其他胚层的发育密切相关。中胚层和内胚层是诱导神经组织和在神经板内建立不对称的重要信号来源。在这个建议中，我们寻求利用有效的遗传和细胞方法在斑马鱼中可用来研究神经外胚层的模式。斑马鱼很适合这种分析。斑马鱼的胚胎是透明的，胚胎发育迅速。这些特性促进了对正常和异常胚胎发育的详细观察。斑马鱼产生大量的后代，这除了促进表型表征外，还增强了遗传分析。提出的实验利用几种特征良好的斑马鱼突变来研究诱导和模式神经组织的分子机制。一般的方法是考虑产生前后神经组织的所有信号。将测试神经诱导和模式的模型。提出了一种遗传筛选，以确定新的基因座，破坏前神经规范。筛选利用产生单倍体斑马鱼胚胎的能力，以增加筛选的吞吐量。筛选有两个组成部分：一种基于形态学的方法来识别破坏前神经模式的突变增强子（bozozok），另一种基于原位的方法来检测phox2a转录因子表达域的改变。在试点筛选中发现的一个有希望的突变改变了前神经模式，并将详细研究。因为所有脊椎动物在神经系统的组织结构上都有基本的相似之处，所以了解控制斑马鱼神经模式的遗传网络将为包括人类在内的其他物种的发育提供重要的见解。几种破坏胚胎发育的斑马鱼突变具有与常见的人类先天性畸形（前脑无裂畸形）相似的前神经缺陷，并且具有相似的病因。破译脊椎动物轴的形成机制也可能为了解其他人类发育障碍的原因提供线索。

DESCRIPTION (provided by applicant): The diversity of cell types within the vertebrate nervous system depends on patterning events that occur at early stages of development. The specification and patterning of neural tissue is closely coupled to the development of the other germ layers. The mesoderm and endoderm are important sources of signals that induce neural tissue and establish asymmetries within the neural plate. In this proposal, we seek to utilize the potent genetic and cellular methodologies available in the zebrafish to study patterning of the neural ectoderm. The zebrafish is well suited to this analysis. Zebrafish embryos are transparent and embryonic development occurs rapidly. These attributes foster detailed observation of normal and aberrant embryonic development. Zebrafish produce large numbers of offspring, which in addition to facilitating phenotypic characterization, enhances genetic analysis. The proposed experiments utilize several well characterized zebrafish mutations to investigate the molecular mechanisms that induce and pattern neural tissue. The general approach is to account for all the signals that generate anterior and posterior neural tissue. Models for both neural induction and patterning will be tested. A genetic screen is proposed to identify novel loci that disrupt anterior neural specification. The screen takes advantage of the ability to generate haploid zebrafish embryos in order to increases the throughput of the screen. There are two components to the screen: a morphology based approach to identify enhancers of a mutation (bozozok) which disrupts anterior neural patterning and an in situ based effort to detect alterations of the expression domains of the phox2a transcription factor. One promising mutation identified in a pilot screen alters anterior neural patterning and will be studied in detail. Because all vertebrates share fundamental similarities in the organization of their nervous systems, understanding the genetic networks that govern neural patterning in zebrafish will provide important insights into development of other species, including humans. Several zebrafish mutations have that disrupt embryonic development have anterior neural defects similar to a common human congenital abnormality, holoprosencephaly, and share similar etiologies. Deciphering the mechanisms of vertebrate axis formation may also provide insight into the causes other human developmental disorders.