Finite element models of flagella with sliding radial spokes and interdoublet links exhibit propagating waves under steady dynein loading
Finite element models of flagella with sliding radial spokes and interdoublet links exhibit propagating waves under steady dynein loading
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DOI：
10.1002/cm.21432
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发表时间：
2018-05-01
期刊：
影响因子：
2.9
通讯作者：
Bayly, Philip V.
中科院分区：
文献类型：
--
作者：
Hu, Tianchen;Bayly, Philip V.
鞭毛是如何产生推进性的振荡波形的仍不清楚。虽然众所周知，动力蛋白马达，结合被动的细胞骨架元件，驱动轴丝的弯曲，通过施加剪切力和弯曲力矩的微管偶极子，节奏的起源仍然是神秘的。大多数鞭毛振荡的概念模型涉及动力蛋白的调节或转换，因此动力蛋白的活动首先在轴丝的一侧，然后另一侧，驱动弯曲。相反，最近有人提出了一种基于动态结构不稳定性的“粘弹性颤振”机制。粘性流体中耦合弹性梁的简单数学模型，在受到足够大的稳定、轴向分布的动力蛋白力的作用下，可以表现出振荡运动，而无需任何切换或动态调节。在这里，我们介绍了更现实的有限元（FE）模型的6双和9双鞭毛，径向辐条和interdoublet链接，沿沿着中心对或相应的双。这些模型演示了粘弹性颤振机制。在临界力阈值之上，这些模型表现出典型的颤振不稳定性的推进、波动振荡的突然发作。稳态动力蛋白力或粘性阻力的大小和空间分布的变化，导致与实验观察定性一致的行为。这项研究表明，有限元模型模拟鞭毛跳动过程中轴丝组件之间的非线性相互作用的能力，并支持粘弹性颤振作为鞭毛振荡的机制的可扩展性。
It remains unclear how flagella generate propulsive, oscillatory waveforms. While it is well known that dynein motors, in combination with passive cytoskeletal elements, drive the bending of the axoneme by applying shearing forces and bending moments to microtubule doublets, the origin of rhythmicity is still mysterious. Most conceptual models of flagellar oscillation involve dynein regulation or switching, so that dynein activity first on one side of the axoneme, then the other, drives bending. In contrast, a "viscoelastic flutter" mechanism has recently been proposed, based on a dynamic structural instability. Simple mathematical models of coupled elastic beams in viscous fluid, subjected to steady, axially distributed, dynein forces of sufficient magnitude, can exhibit oscillatory motion without any switching or dynamic regulation. Here we introduce more realistic finite element (FE) models of 6-doublet and 9-doublet flagella, with radial spokes and interdoublet links that slide along the central pair or corresponding doublet. These models demonstrate the viscoelastic flutter mechanism. Above a critical force threshold, these models exhibit an abrupt onset of propulsive, wavelike oscillations typical of flutter instability. Changes in the magnitude and spatial distribution of steady dynein force, or to viscous resistance, lead to behavior qualitatively consistent with experimental observations. This study demonstrates the ability of FE models to simulate nonlinear interactions between axonemal components during flagellar beating, and supports the plausibility of viscoelastic flutter as a mechanism of flagellar oscillation.