de novo formation of left–right asymmetry by posterior tilt of nodal cilia新创的形成左右不对称节点后倾斜的纤毛.pdf

Open access, freely available online PLoS BIOLOGY De Novo Formation of Left–Right Asymmetry by Posterior Tilt of Nodal Cilia 1,2* 1,3 1,4 1,3 5 Shigenori Nonaka , Satoko Yoshiba , Daisuke Watanabe , Shingo Ikeuchi , Tomonobu Goto , Wallace F. Marshall2, Hiroshi Hamada1,3 1 Graduate School of Frontier Biosciences, Osaka University, Japan, 2 Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America, 3 CREST, Japan Science and Technology Corporation, Tokyo, Japan, 4 Molecular Embryology, Department of Biosciences, School of Science, Kitasato University, Kanagawa, Japan, 5 Department of Mechanical Engineering, Tottori University, Tottori, Japan In the developing mouse embryo, leftward fluid flow on the ventral side of the node determines left–right (L-R) asymmetry. However, the mechanism by which the rotational movement of node cilia can generate a unidirectional flow remains hypothetical. Here we have addressed this question by motion and morphological analyses of the node cilia and by fluid dynamic model experiments. We found that the cilia stand, not perpendicular to the node surface, but tilted posteriorly. We further confirmed that such posterior tilt can produce leftward flow in model experiments. These results strongly suggest that L-R asymmetry is not the descendant of pre-existing L-R asymmetry within each cell but is generated de novo by combining three sources of spatial information: antero-posterior and dorso-ventral axes, and the chirality of ciliary movement. Citation: Nonaka S, Yoshiba S, Watanabe D, Ikeuchi S, Goto T, et al. (2005) De novo formation of left–right asymmetry by posterior tilt of nodal cilia.