Williamson R E, Hurley U A, Perkin J L
Eur J Cell Biol. 1984 Jul;34(2):221-8.
Strong irradiation of localized areas of the alga Chara produces chloroplast damage and extensive loss of the actin bundles responsible for cytoplasmic streaming. Immunofluorescence using a monoclonal antibody binding to the actin bundles has been used to follow their regrowth. Bundle regeneration is polarized so that new bundles develop from the ends of the actin bundles delivering endoplasm to the damaged area and not from bundles removing endoplasm. According to the previously established polarity of the actin filaments this growth is occurring from the "barbed" but not the "pointed" ends of the component filaments. The frequently irregular orientation of the regenerated bundles contrasts with the straight, parallel arrangement of the bundles before destruction. The arrangement of the regenerated bundles is suggested to depend on orientation by passive endoplasmic flow rather than a cortical template. As a result, bundles follow sweeping curves and can form a U-turn connecting oppositely polarized bundles normally separated by the neutral line. In addition to development in continuity with the free ends of pre-existing bundles, visualization of small, discrete fluorescent structures suggests that bundles can begin to form in isolation within the damaged areas. The results are discussed in terms of the polarized actin polymerisation seen in vitro, additional controls which may operate on bundle growth in vivo, and the ability of flow to orient F-actin. The relevance of the findings to normal cell ontogeny is assessed.
对轮藻局部区域进行强辐射会导致叶绿体损伤，并使负责细胞质流动的肌动蛋白束大量损失。使用与肌动蛋白束结合的单克隆抗体进行免疫荧光检测，以追踪其再生过程。束的再生是极化的，因此新的束从将内质输送到受损区域的肌动蛋白束末端发育而来，而不是从移除内质的束发育而来。根据先前确定的肌动蛋白丝的极性，这种生长发生在组成丝的“带刺”端而非“尖端”。再生束频繁出现的不规则取向与破坏前束的笔直、平行排列形成对比。再生束的排列被认为取决于被动内质流的取向，而非皮层模板。结果，束呈现出弯曲的轨迹，并且可以形成一个U形转弯，连接通常被中性线隔开的相反极化的束。除了与先前存在的束的自由端连续发育外，小的离散荧光结构的可视化表明束可以在受损区域内独立开始形成。本文根据体外观察到的极化肌动蛋白聚合、体内可能对束生长起作用的其他控制因素以及流动使F - 肌动蛋白取向的能力对结果进行了讨论。评估了这些发现与正常细胞个体发育的相关性。
