MYOFIBRILLAR STRUCTURE IN STRIATED MUSCLE

昆虫飞行肌肉的肌原纤维结构正在被研究。 通过配合使用电子显微镜，X射线衍射， 定量显微镜和生化分析，并强调 肌球蛋白交叉桥的结构和行为。 交叉桥是肌肉收缩的主要推动者， 大多数非肌肉运动，及其高度有序的晶格 IFM中的安排允许使用平均方法提取 跨桥结构处于不同的状态，这可能与 它们棘轮状周期的不同阶段。X射线和光学 衍射标准将指导我们寻找更好的固定 单宁修饰戊二醛的肌动蛋白与交叉桥 酸、二胺和聚乙二醇三氮杂环己烷。速冻 冷冻替代方法将针对稀释物进行优化。 像僵硬和松弛这样的稳定状态的剖分 尝试对动态结构转换进行研究。3-D 10-25 nm切片的计算机重建，基于 多个倾斜视图和倾斜横截面上的 完成僵硬并应用于一组由核苷酸诱导的 国家，以确定大小，形状和变化 交叉桥的区域对齐。计算机建模将会 探索肌动蛋白的EM结构和僵直的交叉桥梁如何 与X射线强度模型相一致。EM-机械 对单一纤维的相关研究将表征两种新的 乙二醇AMPPNP中遇到的交叉桥配置- 状态的诱导进展，并将探索严格的诱导和 张力检查力量的长度--划程、力量 桥梁附着物以及跨桥“滑移”的影响。我们 期望完成跨桥的协调协作研究 EM/X-射线和自旋标记定位及抗体 肌钙蛋白在交叉桥晶格中的定位。在一个 不同的方法，定量显微镜(EM和 干涉)、Percoll浮力密度带和X射线 晶格间距的衍射测量将在 肌丝和肌原纤维干质量含量的研究 制作昆虫和兔子的质量分布图 肌节，确定肌节交叉中的绝对蛋白Conon- 条带，并解决细丝之间的异常差异 质量和整个原纤维质量。

Myofibril structure of insect flight muscle (IFM) is being studied by coordinated use of electron microscopy, X-ray diffraction, quantitative microscopy and biochemical analysis, and emphasis on the structure and behavior of myosin crossbridges. Crossbridges are the primary movers in muscle contraction and most non-muscle motility, and their highly ordered lattice arrangement in IFM permits averaging methods to extract crossbridge structure indifferent states which can be related to different phases of their ratchet-like cycle. X-ray and optical diffraction criteria will guide our search for better fixation of actin and crossbridges by modifying glutaraldehyde with tannic acid, diamines, and polyethylene-glycol triazine. Quick-freeze and freeze-substitution methods will be optimized for thin- sectioning of stable states like rigor and relaxed before attempting the study of dynamic structural transitions. 3-D computer reconstructions from 10-25 nm sections, based on multiple tilt views and on oblique cross sections, will be completed for rigor and applied to a group of necleotide-induced states, to establish definitively the variation in size, shape and domain alignment of crossbridges. Computer modelling will explore how EM structure of actin and crossbridges of rigor can be reconciled with X-ray intensity modelling. EM-mechanical correlation studies of single fibers will characterize two new crossbridge configurations encountered in glycol-AMPPNP- induced progression of states, and will explore rigor induction and tension to examine the length of the power-stroke, strength of bridge attachment, and effects of crossbridge "slippage". We expect to finish coordinated collaborative studies of crossbridge orientation by EM/X-ray and spin-labelling, and antibody localization of troponin within the crossbridge lattice. IN a different approach, quantitative microscopy (EM and interference), buoyant density banding in Percoll, and X-ray diffraction measurement of lattice spacing will be coordinated in studies of dry mass content of myofilaments and fibrils, to produce mass distribution profiles of insect and rabbit sarcomeres, ascertain absolute protein conon in sarcomere cross- bands, and to resolve an anomalous discrepancy between filament mass and whole fibril mass.