The Rudolf Peierls Centre for Theoretical Physics, Clarendon Laboratory, Parks Road, University of Oxford, Oxford OX1 3PU, United Kingdom.
Phys Rev Lett. 2019 Feb 1;122(4):048004. doi: 10.1103/PhysRevLett.122.048004.
There is now growing evidence of the emergence and biological functionality of liquid crystal features, including nematic order and topological defects, in cellular tissues. However, how such features that intrinsically rely on particle elongation emerge in monolayers of cells with isotropic shapes is an outstanding question. In this Letter, we present a minimal model of cellular monolayers based on cell deformation and force transmission at the cell-cell interface that explains the formation of topological defects and captures the flow-field and stress patterns around them. By including mechanical properties at the individual cell level, we further show that the instability that drives the formation of topological defects, and leads to active turbulence, emerges from a feedback between shape deformation and active driving. The model allows us to suggest new explanations for experimental observations in tissue mechanics, and to propose designs for future experiments.
越来越多的证据表明，液晶特征（包括向列有序和拓扑缺陷）出现在细胞组织中，并且具有生物学功能。然而，对于具有各向同性形状的细胞单层中如何出现本质上依赖于粒子伸长的此类特征，这仍然是一个悬而未决的问题。在这篇快报中，我们提出了一个基于细胞变形和细胞-细胞界面力传递的细胞单层最小模型，该模型解释了拓扑缺陷的形成，并捕获了它们周围的流场和应力模式。通过在单个细胞水平上包括机械性能，我们进一步表明，驱动拓扑缺陷形成并导致主动湍流的不稳定性源于形状变形和主动驱动之间的反馈。该模型使我们能够对组织力学中的实验观察提出新的解释，并为未来的实验提出设计方案。
