CELL INTERACTIONS AND THE GENESIS OF NEURONAL ARBORS

描述：本项目的中心目的是在体内探索 轴突终末分支形成的机制， 中枢神经元对周围目标的神经支配。具体 水蛭中枢神经元（P神经元）在发育早期延伸轴突， 开拓目标路径，率先建立终端 领域的在产生这些场的过程中，同源P细胞 禁止对方在对方的领土上广泛生长。 后期生长的神经元（AP细胞）使用这些先驱作为基质， 在目标区域的增长和分支;事实上，先锋是两者兼而有之 这对于正常的Ap细胞乔木的产生是必要的和足够的。 这些结果表明，一系列增强和/或抑制 相互作用调节神经突的延伸、收缩和分支 在水蛭中枢神经元建立外周动脉的过程中。 本项目的工作假设是，这些相互作用（a） 通过影响细胞骨架的组装来调节神经突的生长 组分，和（B）至少部分地由以下组分的变化介导： 细胞内钙水平。这项拨款中提出的实验 旨在测试这些假设，并提供基础， 未来的研究涉及的机制，在信号和 这些细胞的反应，主要的实验方法将是 (1)利用时间推移分析研究乔木生长的运动学 完整动物的充满染料的胚胎神经元，（2）以确定 细胞骨架元素在不同生长阶段的排列， 在通过注射标记的肌动蛋白和微管 亚基转化为单个生长的神经元，通过电子显微镜， （3）探讨细胞骨架变化与细胞凋亡的关系 排列和细胞内钙浓度。这些研究 将提供对生产和选择性回缩的进一步了解 轴突投射，一个共同的和重要的特点，神经支配 的外周组织。

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.