THE DISTRIBUTION OF MOBILE AND STRUCTURAL COMPONENTS AT CHEMICAL SYNAPSES

本项目旨在确定细胞内的扩散分布 以及轴突、树突、神经胶质和突触内的结构成分。 这项工作是重要的，因为本地化之间的关系， 细胞成分的运动及其在突触中的作用 传输 该项目依赖于最近的几项技术 包括直接冷冻、冷冻切片、免疫细胞化学等， 冷冻切片，定量X射线显微分析， 元素特异性X射线成像。 细胞内的定量研究 小脑平行纤维/浦肯野细胞突触的钙分布 表明在所有静息时总钙低于0.7mmol/kg湿重 突触前和突触后细胞器;因此，高水平的钙储存出现 对这些突触的活动来说是不必要的。 膜去极化， 然而，在（细胞外衍生）钙中， 突触前终末和树突状细胞的滑面内质网 刺，而突触囊泡中的是不变的，从而确定 内质网作为钙螯合的场所。 用活跃髓鞘形成的冰冻切片进行免疫细胞化学研究 神经有牵连的细胞骨架和转运蛋白，例如，肌动蛋白， 血影蛋白和驱动蛋白，在合成和插入髓鞘特异性 蛋白PO和髓鞘相关糖蛋白。 同样，一种新的方法 在冷冻切片中使用原位杂交方法揭示了 编码中枢神经系统的mRNA的差异定位 髓鞘特异性蛋白髓鞘碱性蛋白和蛋白脂质蛋白。 因此，该项目继续提供关于 扩散和结构成分之间的详细关系 神经元和神经胶质，以及它们如何调节神经元活动。

This project aims to determine the intracellular distribution of diffusible and structural components within axons, dendrites, glia, and synapses. This work is important because of the relationship between the localization and movement of cellular constituents and their role in synaptic transmission. This project depends on several recent technological advances, including direct freezing, cryosectioning, immunocytochemistry in ultrathin cryosections, and quantitative x-ray microanalysis and element-specific x-ray imaging. Quantitative studies of the intracellular calcium distribution in parallel fiber/Purkinje cell cerebellar synapses indicate that total calcium is below 0.7 mmol/kg wet weight in all resting pre-and postsynaptic organelles; thus, high-level calcium stores appear unnecessary for the activity of these synapses. Membrane depolarization, however, elicits a fivefold increase in (extracellularly derived) calcium in the smooth endoplasmic reticulum of presynaptic terminals and dendritic spines, while that in synaptic vesicles is unchanged, thereby identifying the endoplasmic reticulum as a site of calcium sequestration. Immunocytochemical studies using frozen sections of actively myelinating nerve have implicated cytoskeletal and transport proteins, e.g., actin, spectrin and kinesin, in the synthesis and insertion of the myelin-specific proteins PO and myelin-associated glycoprotein. Similarly, a new approach using in situ hybridization methods in frozen sections has revealed the differential localization of m-RNAs encoding for the central nervous system myelin-specific proteins myelin basic protein and proteolipid protein. Thus, this project continues to provide important new information on the detailed relationship between the diffusible and structural components of neurons and glia, and how these regulate neuronal activity.