ISOLATION OF NOVEL MUTATIONS AFFECTING THE MOUSE EMBRYO

对塑造人体计划的事件的基因控制 哺乳动物胚胎从植入时到基本的身体计划 是在怀孕中期出现的，目前还不太清楚。在此期间， 原肠发育、胚轴确定、胚层发育的关键事件 器官系统的决定和早期分化发生。 了解这些过程的基因控制对于 人类生育和预防人类生殖能力的研究进展 先天缺陷。在这项提案中，ENU突变将被用于 发现一大组控制小鼠重要事件的新基因 在原肠形成和中期妊娠之间的胚胎，以便 定义在建立人体计划中至关重要的遗传途径 小鼠胚胎。50-100个新突变，对 9.5DPC胚胎的形态将被识别和绘制。二 将深入研究基因的类别，那些控制 身体计划的组织和影响背腹的计划 神经管中的图案。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被用来定义组织和 由突变引起的细胞异常。两个突变，5和 118，已经被分离出来的将被深入研究。这条线 5突变会导致体轴后方截断，优先考虑 轴向和轴旁中胚层丢失，神经皱折和 体节形成；这种缺陷的组合在 以前描述过的突变。5号线突变已被定位 到16号染色体上9 cM的间隔，其中没有影响这一方面的基因 的早期开发已在以前本地化，因此 似乎定义了一种新基因。建议进行研究，以定义 原发缺陷导致5号线表型。品系118的突变 阻碍神经管闭合，眼睛发育，并导致 四肢上多了几个指头。118似乎等同于自发的 突变开放脑(OPB)，已被证明会导致腹侧移位 在神经管的细胞命运中。OPB/118的致病基因 表型将利用候选基因或定位基因进行分子克隆 克隆方法。神经管缺陷是最常见的 人类先天畸形并发生在大约1/4的 全世界有1000个婴儿出生。对小鼠的遗传学研究提供了一种独特的 以及了解起因、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.