Ultrastructure of the endoplasmic factor responsible for cytoplasmic streaming in Chara internodal cells.
Ultrastructure of the endoplasmic factor responsible for cytoplasmic streaming in Chara internodal cells.
复制标题
负责节间细胞胞浆流动的内质因子的超微结构。
作者：
R. Nagai;T. Hayama
以前的研究人员提出，轮状细胞中的细胞质流动是内质因子与静止皮质中由微丝组成的纤维相互作用的结果。利用内灌流技术，我们证实了在引入三磷酸腺苷后，通过降低三磷酸腺苷的内部浓度而附着在原纤维上的细胞器沿原纤维移动。切片标本显示，在没有三磷酸腺苷存在的情况下，不同形状的内质细胞器与微丝束相连。每个细胞器上特定区域排列规则的电子致密材料，间距为100-130 nm，从而实现连接。在内质负染标本中对所讨论的细胞器进行了研究。细胞器有一些共同的特征。(1)它们都是膜限制的。(2)它们的大小和构型差异很大。(3)有一个或多个突起。(4)突起多为杆状或角状。(5)突起表面可见直径20~30 nm的小球状小体，排列有序，间距与薄片相同。(6)突起表面常有细丝附着。这些细丝与F-肌动蛋白的直径不同(小于4 nm)，不能与兔骨骼肌重肌球蛋白反应。讨论了细胞器中这些成分在细胞质流动中的作用。报道了一种横向周期约为38 nm的微丝准晶阵列及其光学衍射图。
Previous investigators have proposed that cytoplasmic streaming in Chara internodal cells results from the interaction between an endoplasmic factor and fibrils composed of microfilaments in the stationary cortex. Using the internal perfusion technique, we confirmed the observation that organelles which had been attached to the fibrils by decreasing the internal concentration of ATP moved along the fibrils after ATP was introduced. Thin-sectioned specimens revealed that endoplasmic organelles of various shapes were linked to microfilament bundles in the absence of ATP. Linkage was effected by regularly arranged electron-dense materials with a spacing of 100 -- 130 nm at definite regions on each organelle. The organelles in question were studied in negatively stained preparations of endoplasm. The organelles had some common features. (1) They were all membrane-limited.(2) Their sizes and configurations varied largely. (3) One or more protuberances were present on them. (4) The protuberances were usually rod- or horn-like. (5) Small globular bodies 20--30 nm in diameter were found in ordered array with the same spacing as those in thin sections at the surface of the protuberances. (6) Many fine filaments were always attached to the surface of the protuberances. These fine filaments differed from F-actin in diameter (less than 4 nm) and inability to react with heavy meromyosin from rabbit skeletal muscle. The role of such components of the organelles in cytoplasmic streaming is discussed. A paracrystalline array of microfilaments with a transverse periodicity of about 38 nm is presented, together with its optical diffraction pattern.