GENETIC ANALYSIS OF CELL DIVISION ORIENTATION

在从细菌到哺乳动物的生物体中，某些细胞经历 在发育和生长过程中可复制的分裂模式。的 分裂模式对于形态发生、组织组织形成和 影响发育命运的细胞相互作用。 的取向 分裂的过程也在细胞成分的分离中起作用 在本质上不对称的分裂中。 因此，了解如何 控制分裂模式对于我们理解 基本的发展过程，包括人类的发展过程， 我们对发育障碍的理解 我们正在研究控制 利用线虫C.优雅的， 基因形态和分子分析 我们用的是一种基因 一种鉴定正常不变细胞所需基因的方法 C.线虫胚胎 我们的长期目标是 描述与去除这些基因相关的缺陷， 活性，并在分子水平上分离和研究基因。 的 该提案的具体目标是：1）确定何时何地让 （我们已经证明的一个基因对正常的分裂方向至关重要）和一个 相关基因Irg-1的表达，2）阐明let-99的作用， IRG-1在部门定位和其他发展方面，以及3） 开始研究其他参与控制分裂的基因 导向 为了实现这些目标，我们将使用发育RNA 印迹以确定let-99和Irg-1基因何时表达。 我们将 使用LET-99和LRG-1抗血清来确定何时以及在什么细胞中， 蛋白质是否存在，以及蛋白质是否定位于任何 亚细胞结构可以让我们深入了解功能。 我们将 表征另外的let-99突变（并且如果 需要），以解决是否需要let-99来进行部门定向 而不是早期胚胎发生。 为了确定Irg-1是否是 根据部门定位或其他发展方面的需要，我们将 使用靶选择诱变产生Irg-1突变， 最后，我们建议继续遗传 筛选改变胚胎分裂模式的突变， 为了分离新基因S的等位基因以及 我们之前发现的基因 的一个子集的特征， 新的突变将开始。

In organisms ranging from bacteria to mammals, certain cells undergo reproducible patterns of division during development and growth. The division pattern is important for morphogenesis, tissue organization, and cellular interactions that influence developmental fate. The orientation of division also plays a role in the segregation of cellular components during intrinsically asymmetric divisions. Thus, an understanding of how division patterns are controlled is essential to our understanding of basic developmental processes, including those of humans, and could aid in our understanding of developmental disorders. We are studying the control of cell division pattern using the nematode C. elegans, which is amenable to genetic, morphological and molecular analysis. We are using a genetic approach to identify genes required for the normally invariant cell division pattern of the C. elegans embryo. Our long term goals are to characterize the defects associated with removal of those gene's activities, and isolate and study the genes at the molecular level. The specific goals of this proposal are 1) to determine when and where let-99 (a gene we have shown is critical for normal division orientation) and a related gene Irg-1, are expressed, 2) elucidate the role of let-99 and Irg-1 in division orientation and other aspects of development, and 3) begin the study of other genes involved in controlling division orientation. To accomplish these aims, we will use developmental RNA blots to determine when the let-99 and Irg-1 genes are expressed. We will use LET-99 and LRG-1 antisera to determine when and in what cells the proteins are present, and whether the proteins are localized to any subcellular structures that would give insight into function. We will characterize additional let-99 mutations (and isolate null alleles if necessary) to address whether let-99 is required for division orientation at times other than early embryogenesis. To determine if Irg-1 is required for division orientation or other aspects of development, we will generate Irg-1 mutations using target-selected mutagenesis and characterize the mutant phenotype Finally, we propose to continue genetic screens for mutations that alter the division pattern of the embryo, in order to isolate alleles of new genes s well as additional alleles of genes we previously identified. The characterization of a subset of the new mutations will be initiated.