Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Komaba Institute for Science, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Commun Biol. 2021 Oct 21;4(1):1209. doi: 10.1038/s42003-021-02756-0.
Helical swimming in free-space is a common behavior among microorganisms, such as ciliates that are covered with thousands hair-like motile cilia, and is thought to be essential for cells to orient directly to an external stimulus. However, a direct quantification of their three-dimensional (3D) helical trajectories has not been reported, in part due to difficulty in tracking 3D swimming behavior of ciliates, especially Tetrahymena with a small, transparent cell body. Here, we conducted 3D tracking of fluorescent microbeads within a cell to directly visualize the helical swimming exhibited by Tetrahymena. Our technique showed that Tetrahymena swims along a right-handed helical path with right-handed rolling of its cell body. Using the Tetrahymena cell permeabilized with detergent treatment, we also observed that influx of Ca into cilia changed the 3D-trajectory patterns of Tetrahymena swimming, indicating that the beating pattern of cilia is the determining factor in its swimming behavior.
在自由空间中螺旋游动是微生物的一种常见行为，例如纤毛虫，它们的身体表面覆盖着成千上万根毛发状的运动纤毛，人们认为这种游动方式对于细胞直接感知外部刺激至关重要。然而，由于难以跟踪纤毛虫的三维（3D）游动行为，特别是对于细胞体较小且透明的四膜虫，因此尚未对其 3D 螺旋轨迹进行直接定量。在这里，我们通过对细胞内的荧光微球进行 3D 跟踪，直接观察到四膜虫的螺旋游动。我们的技术表明，四膜虫沿着右手螺旋路径游动，其细胞体呈右手滚动。使用去污剂处理使四膜虫细胞通透后，我们还观察到钙离子流入纤毛会改变四膜虫游动的 3D 轨迹模式，表明纤毛的拍打模式是其游动行为的决定因素。
