Simulation of the nodal flow of mutant embryos with small number of cilia: comparison of mechanosensing and vesicle transport hypotheses

Left-right (L-R) asymmetry in the body plan is determined by nodal flow in vertebrate embryos. Shinohara et al. used Dpcd and Rfx3 mutant mouse embryos and showed that only a few cilia were sufficient to achieve L-R asymmetry. However, the mechanism underlying the breaking of symmetry by such weak ciliary flow is unclear. The flow-mediated signals related to L-R asymmetry have not been clarified; there are two models for L-R symmetry breaking: vesicle transport and mechanosensing. In this study, we developed a computational model of the node system reported by Shinohara et al. and examined feasibilities of two hypotheses with a small number of cilia. With the small number of rotating cilia, flow was induced locally and global strong flow was not observed in the node. Particles were then effectively transported only when they were close to the cilia, and particle transport was strongly dependent on the ciliary positions. Although the maximum wall shear rate was also influenced by ciliary...

脊椎动物胚胎的身体结构左右（L-R）不对称性由节点流（nodal flow）决定。Shinohara等人利用Dpcd和Rfx3突变小鼠胚胎研究发现，仅需少量纤毛即可实现左右不对称性。然而，这种微弱纤毛流打破对称性的潜在机制仍不明确。与左右不对称相关的流介导信号尚未阐明；目前存在两种左右对称性打破模型：囊泡运输（vesicle transport）和机械传感（mechanosensing）。本研究中，我们构建了Shinohara等人报道的节点系统计算模型，并验证了少量纤毛条件下两种假说的可行性。在少量旋转纤毛存在的情况下，节点内仅产生局部诱导流，未观察到全局强流。只有当颗粒靠近纤毛时才能被有效运输，且颗粒运输强烈依赖于纤毛位置。尽管壁面最大剪切速率也受纤毛...