De novo formation of left-right asymmetry by posterior tilt of nodal cilia.
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.
Nonaka
Shigenori
S
Graduate School of Frontier Biosciences, Osaka University, Japan. snonaka@itsa.ucsf.edu
Yoshiba
Satoko
S
Watanabe
Daisuke
D
Ikeuchi
Shingo
S
Goto
Tomonobu
T
Marshall
Wallace F
WF
Hamada
Hiroshi
H
D000818:Animals; D019521:Body Patterning; D002923:Cilia / Q000502:physiology* / Q000648:ultrastructure; D004622:Embryo, Mammalian / Q000502:physiology / Q000648:ultrastructure*; D047108:Embryonic Development; D045604:Extracellular Fluid; D051379:Mice; D008855:Microscopy, Electron, Scanning; D008954:Models, Biological; D012399:Rotation