ISOLATION OF NOVEL MUTATIONS AFFECTING THE MOUSE EMBRYO

基因控制的事件，形状的身体计划， 哺乳动物胚胎从植入到基本身体计划的时间 是如何在怀孕中期出现的还不是很清楚。在此期间， 原肠胚形成、轴决定、胚层形成等关键事件 发生器官系统的决定和早期分化。 了解这些过程的遗传控制对于 人类生育研究的进展和预防人类生育 出生缺陷 在本提案中，ENU诱变将用于 确定了一组控制小鼠重要事件新基因 在原肠胚形成和妊娠中期之间的胚胎， 确定在建立身体计划的关键遗传途径， 小鼠胚胎 50-100个新的突变，有明显的影响， 9.5dpc胚胎的形态将被鉴定和定位。两 将深入研究基因的类别，那些控制 组织的身体计划和那些影响背腹 神经管中的模式。 对于影响这些过程的突变体， 组织学分析、细胞增殖和细胞死亡分析， 分子标志物的表达将用于定义组织， 突变导致的细胞异常 两个突变，5和 118，已经被分离出来，将进行深入研究。 线 5突变导致体轴的后截短， 轴向和近轴中胚层的丧失，以及神经褶和 体节的形成;这种缺陷的组合在 先前特征的突变。 5号线突变已经被定位 到16号染色体上的9 cM间隔，其中没有基因影响这方面 早期的发展已经被本地化，因此 似乎定义了一个新基因。 建议开展研究， 导致5号线表型的主要缺陷。 118号线突变 阻止神经管闭合，眼睛发育， 四肢上的多余手指 118似乎是等位基因的自发 突变开放脑（opb），已被证明会导致腹侧移位 神经管中细胞的命运 负责OPB/118的基因 表型将被分子克隆，使用候选基因或定位 克隆方法。 神经管缺陷是最常见的 人类先天性异常，大约有1/ 全球1000个新生儿。 小鼠的遗传研究提供了一种独特的 和有价值的来源，了解的原因，检测手段， 预防和治疗这类人类出生缺陷。

The genetic control of the events that shape the body plan of the mammalian embryo from the time of implantation until the basic body plan is laid out in midgestation is not well understood. During this time, the critical events of gastrulation, axis determination, germ layer determination and early differentiation of organ systems take place. Understanding the genetic control of these processes is crucial for progress in studies of human fertility and for the prevention of human birth defects. In this proposal, ENU mutagenesis will be used to identify a large set of new genes that control important events in mouse embryo between the time of gastrulation and midgestation in order to define the genetic pathways crucial in setting up the body plan of the mouse embryo. 50-100 new mutations that have clear effects on the morphology of the 9.5 dpc embryo will be identified and mapped. Two classes of genes will be studied in depth, those that control the organization of the body plan and those that affect dorsal-ventral patterning in the neural tube. For mutants that affect these processes, histological analysis, cell proliferation and cell death analysis and expression of molecular markers will be used to define the tissue and cellular abnormalities produced by the mutation. Two mutations, 5 and 118, that have already been isolated will be studied in depth. The line 5 mutation causes posterior truncation of the body axis, a preferential loss of axial and paraxial mesoderm, and failure of neural fold and somite formation; this combination of defects has not been observed in previously-characterized mutations. The line 5 mutation has been mapped to a 9 cM interval on chromosome 16 where no gene affecting this aspect of early development have been localized previously and therefore appears to define a new gene. Studies are proposed to define the primary defect leading to the line 5 phenotype. The line 118 mutation blocks neural tube closure, eye development and causes the formation of extra digits on the limbs. 118 appears to be allelic to the spontaneous mutation open-brain (opb), which has been shown to cause a ventral shift in cell fates in the neural tube. The gene responsible for the opb/118 phenotype will be molecularly cloned, using candidate gene or positional cloning approaches. Neural tube defects are one of the most common human congenital abnormalities and occur in approximately one out of 1000 births world-wide. Genetic studies in the mouse provide a unique and valuable source for understanding of the causes, means of detection, prevention and treatment of this class of human birth defects.