Varriano-Marston E, Franzini-Armstrong C, Haselgrove J C
J Muscle Res Cell Motil. 1984 Aug;5(4):363-86. doi: 10.1007/BF00818256.
Deep-etching and rotary-shadowing techniques were used to describe crossbridges in fish (Chanda ranga) muscle, relaxed and in iodoacetate rigor conditions. Three major fracture planes from rigor muscle were studied using stereomicroscopy and Fourier image analysis. The 1,0 plane reveals alternating thick and thin filaments with the thick filaments frontmost in the fracture and the thin filaments in the recessed plane. All crossbridges coming from the frontmost thick filaments are visible on actin filaments in the 1,0 plane. Fourier transforms of digitized images from these fracture planes exhibit axial periodicities of 14 and 36 nm. The actin layer, a fracture plane just below the myosin filaments in the 1,0 plane, shows end-on views of crossbridges projecting out of the fracture plane and limited transverse alignment of crossbridges. Actin layer Fourier transforms demonstrate a 14 nm reflection associated with the attachment of crossbridges with a mean axial periodicity determined by their myosin origins. The 1,1 lattice direction shows pairs of thin filaments alternated with single thick filaments. In this view, all crossbridges coming from three adjacent myosins are visible. In all fracture planes, decoration of individual thin filaments by crossbridges is variable, but usually one (singlet) or two (doublet) closely spaced crossbridges mark each actin target zone, at intervals of 35-38 nm. Counts of crossbridges decorating actin filaments give an average of four every three target zones. The anticipated stagger of target zones for crossbridges from two adjacent myosin filaments is observed. Alignment of actin target zones across the sarcomere is good. We can distinguish two distinct shapes for rigor crossbridges: a narrow, straight bridge and a wider bridge with a triangular shape. We interpret these as being the appearance of crossbridges with one or two S1 subfragments (single and double headed) respectively. Comparison between rigor and relaxed structures indicates attachment of all crossbridges in rigor.
采用深蚀刻和旋转阴影技术来描述鱼（钱德拉兰加）肌肉中处于松弛状态以及碘乙酸盐僵直状态下的横桥。使用体视显微镜和傅里叶图像分析研究了来自僵直肌肉的三个主要断裂平面。1,0平面显示出粗细肌丝交替排列，粗肌丝在断裂处最靠前，细肌丝在凹陷平面。来自最靠前粗肌丝的所有横桥在1,0平面的肌动蛋白丝上可见。这些断裂平面数字化图像的傅里叶变换呈现出14和36纳米的轴向周期性。肌动蛋白层是1,0平面中位于肌球蛋白丝下方的一个断裂平面，显示出横桥从断裂平面伸出的端视图以及横桥有限的横向排列。肌动蛋白层傅里叶变换显示出与横桥附着相关的14纳米反射，其平均轴向周期性由肌球蛋白起源决定。1,1晶格方向显示成对的细肌丝与单根粗肌丝交替排列。在此视图中，来自三个相邻肌球蛋白的所有横桥都可见。在所有断裂平面中，横桥对单个细肌丝的修饰各不相同，但通常每35 - 38纳米间隔会有一个（单桥）或两个（双桥）紧密间隔的横桥标记每个肌动蛋白靶区。装饰肌动蛋白丝的横桥计数显示每三个靶区平均有四个。观察到来自两个相邻肌球蛋白丝的横桥靶区预期的交错。整个肌节中肌动蛋白靶区的排列良好。我们可以区分僵直横桥的两种不同形状：一种窄的、直的桥和一种宽的、三角形的桥。我们将其分别解释为具有一个或两个S1亚片段（单头和双头）的横桥外观。僵直结构与松弛结构的比较表明在僵直状态下所有横桥都处于附着状态。
