振荡流体流动驱动收缩波随系统尺寸的标度
Oscillatory fluid flow drives scaling of contraction wave with system size
摘要：
跨越所有生命王国的长距离流动对许多生物体的功能至关重要。协调的流动是电力变形的基础，是迁移或发展或传播资源和信号所必需的。一种普遍存在的产生流动的机制，特别是在动物和变形虫中，是肌动蛋白-肌球蛋白皮质驱动的机械变形，其泵送由皮质封闭的流体。然而，目前还不清楚皮层动力学如何自我组织，以产生协调的流量在很大程度上不同规模的生物系统。在这里，我们开发了一个机械化学模型的肌动蛋白皮质力学耦合到收缩触发，可溶性化学品。化学物质本身与由皮层驱动的管状细胞变形产生的流动平流输送。理论模型预测的动态不稳定性，引起稳定的模式皮层收缩波和振荡流。令人惊讶的是，模拟模式扩展到动力学不稳定性的内在长度尺度之外-而是与系统大小成比例。图案随机出现，但可以在增长系统中或通过流动生成边界条件稳健地生成。我们认为振荡流是收缩波随系统尺寸缩放的关键。我们的工作表明，在生物物理模式的重要性，不仅作为一个调节输入或紧急输出，而是作为一个完整的一部分，一个自组织的机器。收缩和流体流动在所有种类的生物中都可以观察到，因此这个概念可能与广泛的系统有关。
英文摘要：
Flows over remarkably long distances are crucial to the functioning of many organisms, across all kingdoms of life. Coordinated flows are fundamental to power deformations, required for migration or development, or to spread resources and signals. A ubiquitous mechanism to generate flows, particularly prominent in animals and amoeba, is acto-myosin cortex driven mechanical deformations that pump the fluid enclosed by the cortex. Yet, it is unclear how cortex dynamics can self-organize to give rise to coordinated flows across the largely varying scales of biological systems. Here, we develop a mechanochemical model of acto-myosin cortex mechanics coupled to a contraction-triggering, soluble chemical. The chemical itself is advected with the flows generated by the cortex driven deformations of the tubular-shaped cell. The theoretical model predicts a dynamic instability giving rise to stable patterns of cortex contraction waves and oscillatory flows. Surprisingly, simulated patterns extend beyond the intrinsic length scale of the dynamic instability - scaling with system size instead. Patterns appear randomly but can be robustly generated in a growing system or by flow-generating boundary conditions. We identify oscillatory flows as the key for the scaling of contraction waves with system size. Our work shows the importance of active flows in biophysical models of patterning, not only as a regulating input or an emergent output, but rather as a full part of a self-organized machinery. Contractions and fluid flows are observed in all kinds of organisms, so this concept is likely to be relevant for a broad class of systems.
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