GENETICS OF NOTOCHORD DEVELOPMENT

这项研究的长期目标是了解行动模式 控制脊索发育的基因。 脊索在轴向中胚层的图案化中起着关键作用 胚胎发育过程中的结构和中枢神经系统。缺陷 脊索内可导致中轴骨骼畸形或发育不全 以及脊髓的损伤。而脊索的功能很好 人们对控制其生长的遗传因素知之甚少。 发展和完整性，从而影响图案的形成过程。 对脊索有不同特异性影响的突变的存在 形成表明：1)躯干中脊索的形成 和Tail是由不同的基因控制的发育过程 元素，以及ii)这些基因在不同的时间和在 前后轴线上的不同区域。 为了理解表面上的时间间隔的分子机制 脊索发育和完整性的空间差异， 细胞周期调控相关基因的分离与功能研究 对这些过程的监管至关重要。日本血吸虫突变株的分析 脊索的正常发育和完整性是 特别是在不同的时间和不同的地区 体轴是分离这类基因的关键。 在本提案中，我们将重点放在蜂窝和 3个这样的突变的分子水平：丹福斯短尾(SD)，它 沿着脊索的整个长度影响脊索的早期，截断(TC)，这 随后，仅在脊索的尾部起作用，Etl4lacZ， 一种新的LacZ-增强子-陷阱诱导的EtI4突变(增强子-陷阱- Iocus-4)基因，只影响脊索的最后端 与SD密切相关，但与SD截然不同。这样做的具体目的是 建议的目标是： L)研究这些基因作用的细胞自主性，并评估 嵌合体中携带这些突变的细胞的发育潜力 胚胎 2)对Etl4lacZ插入突变的基因进行分析，确定其 功能 3)从YAC克隆开始，用染色体走步的方法克隆SD基因 在紧密连锁的Etl4基因上，确定SD的遗传基础 SD基因突变及其功能分析 对这些基因及其作用方式的分析应该有助于 理解明显区域化的生物学意义 基因在脊索发育中的作用。

The long-term objective of this study is to understand the mode of action of genes controlling notochord development. The notochord plays a pivotal role in patterning axial mesodermal structures and the central nervous system during embryogenesis. Defects in the notochord lead to malformations or agenesis of the axial skeleton and of the spinal cord. Whereas the functions of the notochord are well established, little is known about the genetic elements that control its development and integrity and thus influence pattern forming processes. The existence of mutations with different specific effects on notochord formation suggests that i) the formation of the notochord in the trunk and tail are developmental processes governed by distinct genetic elements, and ii) these genes act specifically at different times and in different regions along the anterior-posterior axis. To understand the molecular mechanisms underlying the apparent temporal and spatial differences of notochord development and integrity, the isolation and functional characterization of genes involved in the regulation of these processes is essential. The analysis of mutants in which the normal development and the integrity of the notochord are specifically perturbed at different times and in different regions along the body axis is the key to isolate such genes. In this proposal we will focus on the analysis at the cellular and molecular level of 3 such mutations: Danforth's short tail (Sd), which affects the notochord early along its entire length, truncate (tc), which acts later and only on the caudal part of the notochord, and Etl4lacZ, a novel lacZ-enhancer-trap-induced mutation at the EtI4 (Enhancer-trap- Iocus-4) gene which affects only the very posterior end of the notochord and is closely linked to but distinct from Sd. The specific aims of this proposal are to: l) study the cell autonomy of the action of these genes and assess the developmental potential of cells carrying these mutations in chimeric embryos 2) analyze the gene mutated by the Etl4lacZ insertion and determine its function 3) clone the Sd gene by chromosomal walking with YAC clones starting at the closely linked Etl4 gene, determine the genetic basis for the Sd mutation and analyze the Sd gene and its function The analysis of these genes and their mode of action should help to understand the biological significance of the apparent regionalization of gene action in notochord development.