Tan, Tzer HanMalik-Garbi, MayaAbu-Shah, EnasLi, JunangSharma, AbhinavMacKintosh, Fred C.Keren, KinneretSchmidt, Christoph F.Fakhri, Nikta2018-09-272018-09-272018Tan, Tzer Han, Malik-Garbi, Maya, Abu-Shah, Enas, et al.. "Self-organized stress patterns drive state transitions in actin cortices." <i>Science Advances,</i> 4, no. 6 (2018) AAAS: https://doi.org/10.1126/sciadv.aar2847.https://hdl.handle.net/1911/102728Biological functions rely on ordered structures and intricately controlled collective dynamics. This order in living systems is typically established and sustained by continuous dissipation of energy. The emergence of collective patterns of motion is unique to nonequilibrium systems and is a manifestation of dynamic steady states. Mechanical resilience of animal cells is largely controlled by the actomyosin cortex. The cortex provides stability but is, at the same time, highly adaptable due to rapid turnover of its components. Dynamic functions involve regulated transitions between different steady states of the cortex. We find that model actomyosin cortices, constructed to maintain turnover, self-organize into distinct nonequilibrium steady states when we vary cross-link density. The feedback between actin network structure and organization of stress-generating myosin motors defines the symmetries of the dynamic steady states. A marginally cross-linked state displays divergence-free long-range flow patterns. Higher cross-link density causes structural symmetry breaking, resulting in a stationary converging flow pattern. We track the flow patterns in the model actomyosin cortices using fluorescent single-walled carbon nanotubes as novel probes. The self-organization of stress patterns we have observed in a model system can have direct implications for biological functions.engThis is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.Journal articleeaar2847https://doi.org/10.1126/sciadv.aar2847