THE DISTRIBUTION OF MOBILE COMPONENTS AT CHEMICAL SYNAPSES

该项目旨在确定可扩散和可扩散的 化学突触的结构成分。这项工作意义重大 因为这种运动的本地化和运动之间的关系 组成成分及其在突触传递中的作用。要达到 这个项目是研究突触所必需的分辨率和敏感度 结合了几项重要的技术进步，包括快速 未固定组织的冷冻和冷冻切除，冷冻和冷冻切除 蔗糖保护组织的免疫细胞化学染色，并定量， 元素特定的X射线成像和分析在专门的分析中 电子显微镜。细胞内钙离子分布的研究 小鼠小脑的分子层表明突触前钙 存储不存在，也不是并行活动所必需的 纤维/浦肯野细胞突触。然而，膜去极化是 伴随着细胞外钙进入细胞器的过程 浦肯野细胞的树突，表明需要 突触后元件中的钙处理细胞器。钙的分析 在鱿鱼脑突触体内的分布证实了 突触前钙储存在静息的胆碱能终末。这 制剂也在使用，与一种锑标记的 乙酰胆碱类似物，以确定ACh在哪里被吸收和存储 胆碱能突触体。结构方面的相关研究 突触功能的研究表明，快速冷冻对于 保留不稳定的膜结构的固有组织，例如 水泡。已研究的免疫细胞化学支持参与 肌动蛋白和脑影蛋白在髓鞘形成中的作用，并提供了一种方法 确定细胞骨架蛋白在脑组织中的作用 突触。因此，该项目现在已经开始提供重要的 关于可扩散和可扩散之间详细关系的信息 突触的结构成分，以及这些如何调节突触活动。

This project aims to determine the distribution of diffusible and structural components at chemical synapses. This work is significant because of the relationship between the localization and movement of such constituents and their role in synaptic transmission. To attain the resolution and sensitivty necessary to study synapses, this project combines several significant technological advances, including rapid freezing and cryosectioning of unfixed tissues, cryosectioning and immunocytochemical staining of sucrose-protected tissues, and quantitative, element-specific x-ray imaging and analysis in a specialized analytical electron microscope. Studies of the intracellular calcium distribution in the molecular layer of mouse cerebellum indicate that presynaptic calcium stores are not present and are not required for the activity of parallel fiber/Purkinje cell synapses. Membrane depolarization, however, is accompanied by the loading of extracellular calcium into organelles in the dendrites of Purkinje cells, demonstrating a requirement for calcium-handling organelles in postsynaptic elements. Analysis of calcium distribution in the synaptosomes from squid brain confirm the absence of presynaptic calcium stores in resting cholinergic terminals. This preparation is also being used, in conjunction with an antimony-labeled acetylcholine analog, to determine where ACh is taken up and stored in cholinergic synaptosomes. Correlative studies on structural aspects of synaptic function have shown that rapid freezing is essential for preserving the native organization of labile membrane structures such as vesicles. Immunocytochemical studied have supported the involvement of actin and brain spectrin in myelination, and provided an approach to determining the role of cytoskeletal proteins in the organization of brain synapses. Thus, this project has now begun to provide important information on the detailed relationship between the diffusible and structural components of synapses, and how these regulate synaptic activity.