Mechanism of Nodal Flow: A Conserved Symmetry Breaking Event in Left-Right Axis Determination

The leftward flow in extraembryonic fluid is critical for the initial determination of the left-right axis of mouse embryos. It is unclear if this is a conserved mechanism among other vertebrates and how the directionality of the flow arises from the motion of cilia. In this paper, we show that rabb...

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Bibliographic Details
Published in:Cell 2005-05, Vol.121 (4), p.633-644
Main Authors: Okada, Yasushi, Takeda, Sen, Tanaka, Yosuke, Belmonte, Juan-Carlos Izpisúa, Hirokawa, Nobutaka
Format: Article
Language:English
Subjects:
Amniotic Fluid - physiology
Animals
Biological Evolution
Blastocyst - physiology
Blastocyst - ultrastructure
Body Patterning - physiology
Cells, Cultured
Cilia - physiology
Cilia - ultrastructure
Embryo, Mammalian - embryology
Embryo, Mammalian - ultrastructure
Embryo, Nonmammalian - embryology
Embryo, Nonmammalian - ultrastructure
Functional Laterality - physiology
Mice
Microscopy, Electron, Scanning
Oryzias
Rabbits
Species Specificity
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Summary:The leftward flow in extraembryonic fluid is critical for the initial determination of the left-right axis of mouse embryos. It is unclear if this is a conserved mechanism among other vertebrates and how the directionality of the flow arises from the motion of cilia. In this paper, we show that rabbit and medakafish embryos also exhibit a leftward fluid flow in their ventral nodes. In all cases, primary monocilia present a clockwise rotational-like motion. Observations of defective ciliary dynamics in mutant mouse embryos support the idea that the posterior tilt of the cilia during rotational-like beating can explain the leftward fluid flow. Moreover, we show that this leftward flow may produce asymmetric distribution of exogenously introduced proteins, suggesting morphogen gradients as a subsequent mechanism of left-right axis determination. Finally, we experimentally and theoretically characterize under which conditions a morphogen gradient can arise from the flow.
ISSN:0092-8674
1097-4172
DOI:10.1016/j.cell.2005.04.008