The actin cortex is an active adaptive material, embedded with complex regulatory networks that can sense, generate, and transmit mechanical forces. The cortex exhibits a wide range of dynamic behaviours, from generating pulsatory contractions and travelling waves to forming organised structures. Despite the progress in characterising the biochemical and mechanical components of the actin cortex, the emergent dynamics of this mechanochemical system is poorly understood. Here we develop a reaction-diffusion model for the RhoA signalling network, the upstream regulator for actomyosin assembly and contractility, coupled to an active actomyosin gel, to investigate how the interplay between chemical signalling and mechanical forces regulate stresses and patterns in the cortex. We demonstrate that mechanochemical feedback in the cortex acts to destabilise homogeneous states and robustly generate pulsatile contractions. By tuning active stress in the system, we show that the cortex can generate propagating contraction pulses, form network structures, or exhibit topological turbulence.

中文翻译：

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可兴奋肌动球蛋白皮层的搏动收缩和模式形成

肌动蛋白皮层是一种活跃的适应性材料，嵌入了复杂的调节网络，可以感知、产生和传递机械力。皮层表现出广泛的动态行为，从产生脉动收缩和行波到形成有组织的结构。尽管在表征肌动蛋白皮层的生化和机械成分方面取得了进展，但对该机械化学系统的新兴动力学知之甚少。在这里，我们为 RhoA 信号网络开发了一个反应扩散模型，它是肌动球蛋白组装和收缩的上游调节器，与活性肌动球蛋白凝胶耦合，以研究化学信号和机械力之间的相互作用如何调节皮质中的压力和模式。我们证明了皮层中的机械化学反馈会破坏均匀状态并强烈地产生脉动收缩。通过调整系统中的主动应力，我们表明皮层可以产生传播收缩脉冲、形成网络结构或表现出拓扑湍流。