NEURAL CONTROL OF A MOTOR PROGRAM

这项拟议的研究的目标是了解细胞、基因、 最终导致神经系统控制的分子机制 线虫线虫的排便行为。初级阶段 重点将放在专门的肛门肌的运动控制上。 大便。这项研究将扩展目前对两个 含有GABA的假定运动神经元，称为AVL和DVB，是 是肛门肌肉收缩所必需的。这将通过使用 激光微束在功能上单独消除已识别的神经元 或分组，以确定它们在控制排便方面的作用。 这些结果将导致对完整的 神经元网络在这一行为中起着重要作用。这项研究还将延长 除了23个这样的基因外，还发现了对排便重要的基因 已经确定的基因。为此，一大批有缺陷的突变体 肛门肌肉收缩的控制将被隔离。这一部分是 研究还将使用经典的遗传方法对现有的 显性突变体、上位性试验和突变体的详细测定 表型来表征这些基因的功能。的最终目标是 这项研究将把这种遗传分析扩展到分子水平。 现有的针对推定的 肛门肌运动神经元AVL和DVB，将被用作免疫荧光 线虫身上全是污渍。AVL和DVB的详细结构 将在大量的排便突变体和野生型中进行比较。 这些测试将确定突变体是否改变了细胞的命运 或AVL和DVB的神经元过程引导。其中一个基因EXP-1是 可能是兴奋性GABA神经肌肉的一种成分 由AVL和DVB在肛门肌上形成连接。EXP-L，可能还有一个 在这项研究中发现的少量其他类似基因将被克隆 利用线虫近乎完整的物理图谱和DNA介导法 外源L突变体的转化拯救。该基因(S)将被测序，其 基因产物在体内定位，并在多个组织中表达 其他影响肛门肌功能控制的突变体。这些研究 将致力于了解该基因的分子功能。 这项拟议研究的两个特点与健康相关。 首先，线虫为系统的遗传学研究提供了唯一的模型 排便，这种行为在后生动物中几乎是普遍的，在这种行为中， 是人类的一种广泛的疾病。第二，肛门的运动控制 线虫的肌肉收缩提供了一个不同寻常的好机会 鉴定和分析影响已鉴定的GABA突触的突变体。

The goal of the proposed research is to understand the cellular, genetic, and ultimately molecular mechanisms underlying nervous system control of defecation behavior in the nematode Caenorhabditis elegans. The primary focus will be on motor control of the specialized anal muscles that mediate defecation. The study will extend the current knowledge of two GABA-containing putative motor neurons, called AVL and DVB, that are required for anal muscle contraction. This will be accomplished by using a laser microbeam to functionally eliminate identified neurons, individually or in groups, in order to determine their role in control of defecation. These results will lead to a tentative determination of the complete network of neurons important in this behavior. The study will also extend the identification of genes important for defecation, adding to the 23 such genes already identified. To this end a large set of mutants defective in control of anal muscle contraction will be isolated. This part of the study will also use classical genetic methods of reversion of existing dominant mutants, epistasis tests, and detailed determination of mutant phenotype to characterize the function of these genes. The final aim of the study will be to extend this genetic analysis to the molecular level. Existing monoclonal antibodies, which are directed against the putative anal muscle motor neurons AVL and DVB, will be used as an immunofluorescent stain in C. elegans whole mounts. The detailed structure of AVL and DVB will be compared in the large set of defecation mutants and the wild type. These tests will determine whether the mutants have altered the cell fate or neuronal process guidance of AVL and DVB. One gene, exp-1, is implicated as a possible component of an excitatory GABA neuromuscular junction made by AVL and DVB on the anal muscles. exp-l, and possibly a small set other similar genes identified in this study, will be cloned using the nearly complete physical map of C. elegans and DNA mediated transformation rescue of exp-l mutants. The gene(s) will be sequenced, its gene product localized in vivo, and its expression assessed in the many other mutants that affect control of anal muscle function. These studies will be directed at understanding the molecular function of this gene. Two features of the proposed study are of general health related interest. First, C. elegans provides the only model for the systematic genetic study of defecation, a behavior nearly universal in metazoans, and in which there are a wide range of disorders in humans. Second, motor control of anal muscle contraction in C. elegans provides an unusually good opportunity to identify and analyze mutants affecting an identified GABA synapse.