CELL INTERACTIONS AND THE GENESIS OF NEURONAL ARBORS

描述：该项目的中心目标是在体内探索 轴突终末分支形成的机制和 中枢神经元对外周靶点的神经支配。特定的 水蚤中枢神经元(P神经元)在发育早期延伸轴突， 开辟通向目标的道路，率先建立终点站 菲尔兹。在产生这些场的过程中，同源P细胞 相互抑制对方在对方领土上的广泛发展。 后期生长的神经元(AP细胞)使用这些先驱细胞作为底物 向目标区域增长并在目标区域分支；事实上，开拓者既是 这是产生正常AP细胞株的必要条件和充分条件。 这些结果表明，一系列的增强和/或抑制 相互作用调节神经突起的伸展、收缩和分支 在水蚤中枢神经元建立外周乔木的过程中。 该项目的工作假设是这些相互作用(A) 通过影响细胞骨架的组装来调节轴突生长 组件，以及(B)至少部分地通过以下变化来调节 细胞内钙水平。这项拨款中提议的实验 旨在检验这些假设，并为 未来对信号和信号传递所涉及的机制的研究 这些细胞的反应将是主要的实验方法 (1)用时间推移分析方法研究乔木生长的运动学 对完整动物中充满染料的胚胎神经元的研究，(2)确定 细胞骨架元素在不同生长发育阶段的排列 通过注射标记的肌动蛋白和小管进行实验操作后 亚基转化为单独的生长神经元，并通过电子显微镜， 以及(3)寻找细胞骨架变化之间的关系 排列和细胞内钙离子浓度。这些研究 将提供对生产和选择性撤回的进一步洞察 轴突投射是神经支配的一个共同而重要的特征 外周组织。

DESCRIPTION: The central aim of this project is to explore in vivo the mechanisms underlying the formation of axonal terminal arborizations and the innervation of peripheral targets by central neurons. Specific leech central neurons (P neurons) extend axons early in development that pioneer the paths to the targets and are the first to establish terminal fields. In the process of generating these fields, homologous P cells inhibit each other from growing extensively in each other's territory. Later-growing neurons (AP cells) use these pioneers as substrates for growth to and branching at the target area; in fact, the pioneer is both necessary and sufficient for the generation of normal Ap cell arbors. These results indicate that a series of enhancing and/or inhibiting interactions modulate the extension, retraction and branching of neurites during the establishment of peripheral arbors by leech central neurons. The working hypotheses of this project are that these interactions (a) modulate neurite growth by affecting the assembly of cytoskeletal components, and (b) are mediated at least in part by changes in intracellular calcium levels. The experiments proposed in this grant are designed to test these hypotheses and to provide the bases for future examination of the mechanisms involved in the signaling and responses of these cells the principal experimental approaches will be (1) to study the kinematics of arbor growth using time-lapse analysis of dye-filled embryonic neurons in intact animals, (2) to determine the arrangement of cytoskeletal elements at various stages of growth and after experimental manipulations by injecting tagged actin and tubuli subunits into individual growing neurons, and by electron microscopy, and (3) to search for relations between changes in cytoskeletal arrangements and intracellular calcium concentration. These studies will provide further insight into production and selective retraction of axonal projections, a common and important feature of the innervation of peripheral tissues.