Motion analysis and ultrastructural study of a colonial diatom, Bacillaria paxillifer.
Motion analysis and ultrastructural study of a colonial diatom, Bacillaria paxillifer.
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群落硅藻 Bacillaria paxillifer 的运动分析和超微结构研究。
作者：
Yamaoka;N.;Suetomo;Y.;Yoshihisa;T.;and Sonobe;S.
羽状硅藻（Bacillaria paxillifer）形成一个菌落，其中相邻细胞平滑且几乎连续地滑动，但没有观察到明显的驱动运动的装置，例如鞭毛或纤毛。迄今为止，这种运动的机制和生理意义尚不清楚。在这里，我们报告了 B 的滑翔运动的定量分析。用光学和电子显微镜对该硅藻进行柱状体和形态分析。相邻两对的滑行 B.集落中的柱状细胞以相当恒定的周期循环，而集落之间的平均滑动周期从几秒到10秒的倍数不等。肌动蛋白和肌球蛋白抑制剂可逆地损害滑动，表明肌动球蛋白系统参与其中。事实上，我们通过荧光标记的鬼笔环肽染色观察到中缝附近有两个紧密排列的肌动蛋白束。使用电子显微镜，我们观察到类似于荧光显微镜下看到的肌动蛋白束的丝状结构，并且我们还发现了位于质膜和这些肌动蛋白样丝之间的新型电子致密结构。根据这些和其他观察结果，我们建议 B. Paxillifer还使用肌动蛋白束并提出一种推定的肌球蛋白作为单细胞硅藻滑动的分子马达。
The pennate diatom,Bacillaria paxillifer, forms a colony in which adjacent cells glide smoothly and almost continuously, yet no obvious apparatus driving the movement, such as flagella or cilia, is observed. Thus far, neither the mechanism nor physiological significance of this movement has been well understood. Here, we report quantitative analysis of the gliding motion ofB. paxilliferand morphological analysis of this diatom with light and electron microscopes. The gliding of pairs of adjacentB. paxillifercells in a colony was cyclic with rather constant periods while the average gliding period varied from a few seconds to multiples of 10 s among colonies. The gliding was compromised reversibly by inhibitors for actin and myosin, suggesting involvement of the actomyosin system. Indeed, we observed two closely apposed actin bundles near the raphe by fluorescence-labeled phalloidin staining. Using electron microscopy, we observed filamentous structures that resemble the actin bundles seen with fluorescence microscopy, and we also found novel electron-dense structures located between the plasma membrane and these actin-like filaments. From these and other observations, we suggest thatB. paxilliferalso uses actin bundles and propose a putative myosin as a molecular motor in the gliding of unicellular diatoms.
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