ELEMENTAL AND STRUCTURAL ORGANIZATION OF NEURONS AND GLIA

这两部分的项目研究的组织和功能， 神经元和神经胶质中的特殊膜。 第一部分旨在 表征突触活动的钙调节平行 小脑皮质的纤维/浦肯野细胞突触。 重大进展 冰冻切片技术及新的分析方法的应用 仪器-低温、高分辨率、场发射扫描 透射电子显微镜（见项目Z01-NS-02836 - 01 LN）-已允许通过能量分散的详细重新调查 X射线微区分析（EDX）内质网（ER）在 调节突触内的钙离子 延长 以前的研究，结果表明，作为积累的结果， 在突触活动期间释放钙， 树突棘中ER在两个特征之间循环 集中状态。 终末内质网钙离子浓度 树突在活动过程中的变化甚至更显着，但模式 更加复杂。 对来自新的、在 小脑的体外制备，以及新的 海马脑片的器官型培养，表明这是可能的 来分析突触和树突， states. 在第2部分中，研究了特殊膜的形成， 髓鞘组装的背景。 少突胶质细胞和雪旺细胞利用 不同的合成、分选、运输和组装途径 不同的髓鞘特异性蛋白;这些途径中的一些似乎 依赖于基于微管（MT）的细胞内转运。 共焦光 显微镜下显示髓鞘化雪旺细胞的核周区 包含一个主要的，无中心放置的高尔基体， 一个微管组织中心和主要的MT网络。 这 排列与MT束在节间的 施旺细胞，其中显著部分（约。30%）的这些束 以（+）-端朝向索马的方式组装。 免疫金 电子显微镜显示，从发育的2 - 35天， 节间不基于以下因素被分类为域： 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).