标题： 分子马达稳健地驱动活性凝胶达到临界连接状态 显示英文标题

标题： Molecular motors robustly drive active gels to a critically connected state

摘要： 生命系统常常表现出内部驱动：活跃的分子过程驱动着非平衡现象，例如新陈代谢或迁移。 活性凝胶构成了一类引人入胜的内部驱动物质，其中分子马达会在聚合物网络内部施加局部应力。 有证据表明，网络交联对于允许马达诱导宏观收缩是必要的。 然而，缺乏对网络连通性如何促成收缩的定量理解。 在这里我们通过实验表明，肌球蛋白马达会将交联的肌动蛋白聚合物网络收缩为具有无标度大小分布的聚集体。 这种临界行为出现在出乎意料广泛的交联浓度范围内。 为了理解这种鲁棒性，我们开发了一个考虑网络重构的收缩网络的定量模型：马达通过迫使交联点解离来降低连通性。 矛盾的是，为了协调全局收缩，马达的活动应该较低。 否则，马达会使最初连接良好的网络达到一个临界状态，在整个网络中形成裂痕。 显示英文摘要

摘要： Living systems often exhibit internal driving: active, molecular processes drive nonequilibrium phenomena such as metabolism or migration. Active gels constitute a fascinating class of internally driven matter, where molecular motors exert localized stresses inside polymer networks. There is evidence that network crosslinking is required to allow motors to induce macroscopic contraction. Yet a quantitative understanding of how network connectivity enables contraction is lacking. Here we show experimentally that myosin motors contract crosslinked actin polymer networks to clusters with a scale-free size distribution. This critical behavior occurs over an unexpectedly broad range of crosslink concentrations. To understand this robustness, we develop a quantitative model of contractile networks that takes into account network restructuring: motors reduce connectivity by forcing crosslinks to unbind. Paradoxically, to coordinate global contractions, motor activity should be low. Otherwise, motors drive initially well-connected networks to a critical state where ruptures form across the entire network.