CILIARY MOVEMENT AND ITS CONTROL IN PARAMECIUM
CILIARY MOVEMENT AND ITS CONTROL IN PARAMECIUM
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DOI：
10.1111/j.1550-7408.1984.tb04285.x
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发表时间：
1984-01-01
期刊：
影响因子：
--
通讯作者：
SUGINO, K
中科院分区：
文献类型：
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作者：
NAITOH, Y;SUGINO, K
外dou-c块中的ILIARY节拍和活动滑动区域。草履虫的纤毛表现出三维运动（10）。在搏动周期的有效冲程阶段，纤毛的弯曲发生在基底区域附近，而纤毛的其余部分或多或少是直的。因此，纤毛，直立在细胞表面上，在有效的中风开始时稍微向后倾斜，移动得很像一根柱子，首先直立在地面上，然后倒下。这种运动一直持续到纤毛几乎平行于细胞表面（图1A，1-3）。在随后的恢复划水阶段，纤毛逆时针旋转（从上面看），同时站起来，直到它返回到下一个有效划水开始的起始位置。由于基部的弯曲逐渐向端部发展，在恢复行程中纤毛呈弯曲的鞭状（图1A，4-7）。鞭状运动纤毛所受到的粘性反作用力小于直纤毛所受到的粘性反作用力。因此，周围的介质被纤毛沿着纤毛在有效冲程结束时所指向的大致方向驱动。这就是所谓的“有效中风的方向”或简单的“纤毛的节拍方向。纤毛的弯曲是由ATP激发的动力微管蛋白跨桥激活产生的外部双联体之间的主动滑动引起的（滑动微管假说; 27，31）。据预计，时间变化的位置和范围内的主动滑动区域的外部双峰是负责改变一个跳动的纤毛的配置。最近，我们基于滑动微管假说和流体力学原理（28），制作了一个计算机模型来模拟草履虫的纤毛跳动。我们估计了9个外部双峰中活动滑动区域的分布（29，30）。建立该模型的基本假设是：1）在相邻的外偶极子（27）之间发生主动滑动; 2）当被激活时，第N个外偶极子驱动第（N+“）个外偶极子朝向尖端向上（26，萨提亚，本次研讨会）; 3）在纤毛内给定的化学条件下，相邻的双线之间的滑动速度保持恒定，与双联体中活性区的位置和范围无关（8，32）; 4）在给定的化学条件下，纤毛的刚度是恒定的（9）; 5）双联体之间的滑动仅在基部区域受到限制（27）; 6）主动滑动区域不一定是直的，可以通过另一对双联体之间滑动产生的力而弯曲; 7）纤毛的主动弯曲力矩是每对双联体内滑动产生的弯曲力矩的矢量和; 8）外部粘性根据斯托克斯定律限制纤毛运动，即纤毛的每个元件具有与其长度和速度成比例的粘性阻力; 9）当纤毛在垂直于其纵轴的方向上运动时，其对纤毛元件的粘性阻力比其在轴向方向上运动时大两倍（4）; 10）主动弯矩
ILIARY beat and active sliding regions in the outer dou-c biets. A cilium of Paramecium exhibits movement in three dimensions (10). In the effective stroke phase of the beat cycle, bending of the cilium occurs near the basal region, while the rest of the cilium is more or less straight. Thus, the cilium, which stands straight upon the cell surface, leaning slightly toward the back at the beginning of the effective stroke, moves much like a pole, first standing straight upon the ground, then falling down. The movement continues until the cilium comes to lie nearly parallel to the cell surface (Fig. IA, 1-3). In the subsequent recovery stroke phase the cilium gyrates counterclockwise (as seen from above) while standing up, until it returns to the starting position for the beginning of the next effective stroke. Since the bending at the basal region gradually progresses towards the tip, the cilium takes a curved whip-like shape during the recovery stroke (Fig. lA, 4-7). The viscous counterforce experienced by a moving cilium of whip-like shape is smaller than that experienced by a straight cilium. The surrounding medium is consequently driven by the cilium in the approximate direction toward which the cilium points at the end of the effective stroke. This is called'the direction of the effective stroke'or simply'the beat direction of the cilium.'Bending of the cilium is caused by active sliding between outer doublets produced by ATP-energized activation of their dyneintubulin cross-bridges (the sliding microtubule hypothesis; 27, 3 1). It is expected that time change in both the location and the extent of the active sliding regions in the outer doublets are responsible for changing the configuration of a beating cilium. Recently, we made a computer model for the simulation of ciliary beat of Paramecium based on the sliding microtubule hypothesis and principles of hydrodynamics (28). We estimated the distribution of active sliding regions in the nine outer doublets (29, 30). The basic assumptions for making the model are 1) active sliding occurs between adjacent outer doublets (27); 2) the Nth outer doublet drives the (N+') th outer doublet up toward the tip when activated (26, Satir, this symposium); 3) under given chemical conditions within the cilium, the sliding velocity between adjacent doublets remains constant, independent of the location and extent of the active region in a doublet pair (8, 32); 4) under given chemical conditions the stiffness of the cilium is constant (9); 5) sliding between the doublets is restrained only at the basal region (27); 6) a region of active sliding is not necessarily straight and may be bent by forces generated by sliding between another pair of doublets; 7) active bending moment of a cilium is a vector sum of bending moments generated by sliding within each pair of doublets; 8) external viscosity restricts ciliary movement according to Stokes' law, namely, each element of a cilium has viscous resistance proportional to its length and velocity; 9) the viscous resistance against an element ofa cilium is two times greater when it moves in a direction perpendicular to its longitudinal axis than when it moves in its axial direction (4); 10) active bending moment