ELEMENTAL AND STRUCTURAL ORGANIZATION OF NEURONS AND GLIA

这个由两部分组成的项目研究了 神经元和神经胶质细胞中的特化膜。第一部分旨在 钙对突触活动的平行调节特征 小脑皮质的纤维/浦肯野细胞突触。取得的重大进展 冷冻切片技术及一种新型解析器的应用 仪器-低温、高分辨率、场发射扫描 透射电子显微镜(在项目Z01-NS-02836-01中描述 Ln)-已允许能量分散公司进行详细的重新调查 内质网在脑出血中作用的X射线微区分析 调节这些突触的细胞内钙离子。扩展 以前的研究结果表明，由于积累的结果 在突触活动中释放钙，细胞内的钙含量 树突棘的内质网在两个特征之间循环 浓度状态。内质网终末钙浓度的测定 树突在活动过程中变化更剧烈，但其模式 要复杂得多。来自NEW，IN的冷冻切片的初步EDX分析 小脑的体外制备及新陈代谢产物结构分析 海马片的器官型培养，表明这是可能的 分析符合药理学定义的突触和树突 各州。在第二部分中，我们研究了特化膜的形成 髓鞘组装的背景。少突胶质细胞和雪旺细胞使用 合成、分选、运输和组装的不同途径 不同的髓鞘特异性蛋白；其中一些途径似乎 依赖于基于微管(MT)的细胞内转运。共焦光 显微镜下可见髓鞘雪旺细胞的核周区域 包含一个主要的、偏心放置的高尔基体，与 一个微管组织中心和一个主要的MT网络。这 排列与节间的MT束形成对比 Schwann细胞，其中相当大的部分(约30%)这些捆绑包 被组装成(+)端指向胞体。免疫金 电子显微镜显示，从发育的2-35天，MTS 节点间不会基于以下项被分类为域 微管相关蛋白结合或翻译后修饰 (乙酰化和酪氨酸化)。

This two-part project studies the organization and function of specialized membranes in neurons and glia. The first part aims to characterize calcium regulation of synaptic activity in parallel fiber/Purkinje cell synapses of the cerebellar cortex. Major advances in frozen sectioning technology and the application of a new analytical instrument-the low-temperature, high-resolution, field-emission scanning transmission electron microscope (described in Project Z01 -NS-02836-01 LN)- have permitted a detailed re-investigation by energy-dispersive x-ray microanalysis (EDX) of the role of endoplasmic reticulum (ER) in regulating intracellular calcium in these synapses. Extending the previous study, the results show that, as a consequence of accumulating and releasing calcium during synaptic activity, the calcium content of the ER in dendritic spines cycles between two characteristic concentration states. The calcium concentration of ER in terminal dendrites changes even more dramatically during activity, but the pattern is more complex. Preliminary EDX analysis of cryosections from new, in vitro preparations of cerebellum, as well as structural analysis of new organotypic culture of hippocampal slices, indicate that it is possible to analyze synapses and dendrites which are in pharmacologically defined states. In Part 2, the formation of specialized membranes is studied in the context of myelin assembly. Oligodendrocytes and Schwann cells use distinct pathways for synthesis, sorting, transport and assembly of different myelin-specific proteins; some of these pathways appear to depend on microtubule (MT)-based intracellular transport. Confocal light microscopy shows that the perinuclear region of myelinating Schwann cells contain a principal, acentrically placed Golgi apparatus associated with one microtubule organizing center and a major MT network. This arrangement contrasts with the MT bundles in the internodes of the Schwann cell, where a significant fraction (approx. 30%) of these bundles are assembled with the (+)-end directed toward the soma. Immunogold electron microscopy shows that from 2-35 days of development, the MTs of the internode are not sorted into domains on the basis of microtubule-associated protein binding or post-translational modification (acetylation and tyrosination).