Takahashi Toshiyuki, Shirai Yohji, Kosaka Toshikazu, Hosoya Hiroshi
Graduate School of Biological Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
PLoS One. 2007 Dec 26;2(12):e1352. doi: 10.1371/journal.pone.0001352.
A green ciliate Paramecium bursaria, bearing several hundreds of endosymbiotic algae, demonstrates rotational microtubule-based cytoplasmic streaming, in which cytoplasmic granules and endosymbiotic algae flow in a constant direction. However, its physiological significance is still unknown. We investigated physiological roles of cytoplasmic streaming in P. bursaria through host cell cycle using video-microscopy. Here, we found that cytoplasmic streaming was arrested in dividing green paramecia and the endosymbiotic algae proliferated only during the arrest of cytoplasmic streaming. Interestingly, arrest of cytoplasmic streaming with pressure or a microtubule drug also induced proliferation of endosymbiotic algae independently of host cell cycle. Thus, cytoplasmic streaming may control the algal proliferation in P. bursaria. Furthermore, confocal microscopic observation revealed that a division septum was formed in the constricted area of a dividing paramecium, producing arrest of cytoplasmic streaming. This is a first report to suggest that cytoplasmic streaming controls proliferation of eukaryotic cells.
一种绿色纤毛虫草履虫，体内携带着数百个内共生藻类，呈现出基于微管的旋转式胞质环流，其中胞质颗粒和内共生藻类沿恒定方向流动。然而，其生理意义仍然未知。我们通过视频显微镜利用宿主细胞周期研究了草履虫胞质环流的生理作用。在此，我们发现正在分裂的绿色草履虫中的胞质环流会停止，并且内共生藻类仅在胞质环流停止期间增殖。有趣的是，用压力或微管药物阻止胞质环流也会独立于宿主细胞周期诱导内共生藻类增殖。因此，胞质环流可能控制着草履虫中藻类的增殖。此外，共聚焦显微镜观察显示，在正在分裂的草履虫的收缩区域形成了一个分裂隔膜，导致胞质环流停止。这是首次表明胞质环流控制真核细胞增殖的报告。
