Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom.
PLoS One. 2021 Apr 8;16(4):e0249060. doi: 10.1371/journal.pone.0249060. eCollection 2021.
Active oscillators, with purely hydrodynamic coupling, are useful simple models to understand various aspects of motile cilia synchronization. Motile cilia are used by microorganisms to swim and to control the flow fields in their surroundings; the patterns observed in cilia carpets can be remarkably complex, and can be changed over time by the organism. It is often not known to what extent the coupling between cilia is due to just hydrodynamic forces, and neither is it known if it is biological or physical triggers that can change the dynamical collective state. Here we treat this question from a very simplified point of view. We describe three possible mechanisms that enable a switch in the dynamical state, in a simple scenario of a chain of oscillators. We find that shape-change provides the most consistent strategy to control collective dynamics, but also imposing small changes in frequency produces some unique stable states. Demonstrating these effects in the abstract minimal model proves that these could be possible explanations for gait switching seen in ciliated micro organisms like Paramecium and others. Microorganisms with many cilia could in principle be taking advantage of hydrodynamic coupling, to switch their swimming gait through either a shape change that manifests in decreased coupling between groups of cilia, or alterations to the beat style of a small subset of the cilia.
具有纯水力耦合的有源振荡器是理解运动纤毛同步的各个方面的有用的简单模型。运动纤毛被微生物用来游动并控制其周围的流场；在纤毛地毯中观察到的模式可以非常复杂，并且可以随着时间的推移被生物体改变。目前还不清楚纤毛之间的耦合在多大程度上仅仅是由于水力，也不知道是什么生物或物理触发因素可以改变动态集体状态。在这里，我们从一个非常简化的角度来处理这个问题。我们描述了三种可能的机制，在振荡器链的简单场景中，可以实现动态状态的切换。我们发现，形状变化提供了控制集体动力学的最一致策略，但即使施加较小的频率变化也会产生一些独特的稳定状态。在抽象的最小模型中证明这些效应可以证明，这些可能是草履虫等纤毛微生物中所见的步态切换的可能解释。具有许多纤毛的微生物原则上可以利用水力耦合，通过群体纤毛之间的耦合减少或少数纤毛的拍打风格改变来切换其游动步态。
