PDF(Pubmed)
Abstract：
Shape changes of epithelia during animal development, such as convergent extension, are achieved through concerted mechanical activity of individual cells. While much is known about the corresponding large scale tissue flow and its genetic drivers, fundamental questions regarding local control of contractile activity on cellular scale and its embryo-scale coordination remain open. To address these questions, we develop a quantitative, model-based analysis framework to relate cell geometry to local tension in recently obtained timelapse imaging data of gastrulating Drosophila embryos. This analysis provides a systematic decomposition of cell shape changes and T1-rearrangements into internally driven, active, and externally driven, passive, contributions. Our analysis provides evidence that germ band extension is driven by active T1 processes that self-organize through positive feedback acting on tensions. More generally, our findings suggest that epithelial convergent extension results from controlled transformation of internal force balance geometry which combines the effects of bottom-up local self-organization with the top-down, embryo-scale regulation by gene expression.
摘要：
动物发育过程中上皮的形态变化,如收敛扩展，是通过单个细胞的协同机械活动来实现的。虽然人们对相应的大规模组织流及其遗传驱动因素了解很多，细胞尺度协调的问题仍然悬而未决。我们建议可以根据组织内的机械相互作用和瞬时力平衡来理解这种协调。使用整个胚胎成像数据进行果蝇原肠胚形成，我们利用局部皮质张力平衡与细胞几何形状之间的关系。这揭示了主动张力和被动全局变形的局部正反馈如何解释协调的细胞重排。我们开发了一个模型，该模型桥接了细胞和组织的尺度动力学，并预测了总组织延伸对细胞堆积的初始各向异性和六边形顺序的依赖性。我们的研究提供了对局部细胞尺度活动中整体组织形状编码的一般见解。
■通过皮质张力平衡的受控转换来解释组织流动正张力反馈驱动活跃的细胞插入细胞插入的协调需要局部张力构型的顺序张力动力学模型预测总组织形状从初始细胞顺序的变化。
■通过皮质张力平衡的受控转换来解释组织流动正张力反馈驱动活跃的细胞插入细胞插入的协调需要局部张力构型的顺序张力动力学模型预测总组织形状从初始细胞顺序的变化。
