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Two rotating cilia in the node cavity are sufficient to break left–right symmetry in the mouse embryo

2012; Nature Portfolio; Volume: 3; Issue: 1 Linguagem: Inglês

10.1038/ncomms1624

2041-1723

Kyosuke Shinohara, Aiko Kawasumi, Atsuko Takamatsu, Satoko Yoshiba, Yanick Botilde, Noboru Motoyama, Walter Reith, Bénédicte Durand, Hidetaka Shiratori, Hiroshi Hamada,

Microtubule and mitosis dynamics

Determination of left–right asymmetry in mouse embryos is achieved by a leftward fluid flow (nodal flow) in the node cavity that is generated by clockwise rotational movement of 200–300 cilia in the node. The precise action of nodal flow and how much flow input is required for the robust read-out of left–right determination remains unknown. Here we show that a local leftward flow generated by as few as two rotating cilia is sufficient to break left–right symmetry. Quantitative analysis of fluid flow and ciliary rotation in the node of mouse embryos shows that left–right asymmetry is already established within a few hours after the onset of rotation by a subset of nodal cilia. Examination of various ciliary mutant mice shows that two rotating cilia are sufficient to initiate left–right asymmetric gene expression. Our results suggest the existence of a highly sensitive system in the node that is able to sense an extremely weak unidirectional flow, and may favour a model in which the flow is sensed as a mechanical force. The left–right asymmetry of an organism is patterned during development and is determined by fluid flow created by the movement of cilia. In this study, the asymmetry is shown to be determined early after the movement of cilia is established and that only two rotating cilia are required for breaking symmetry.