TY - JOUR
T1 - Symmetry breakage in the vertebrate embryo
T2 - When does it happen and how does it work?
AU - Blum, Martin
AU - Schweickert, Axel
AU - Vick, Philipp
AU - Wright, Christopher V.E.
AU - Danilchik, Michael V.
N1 - Funding Information:
We are grateful to Rebecca Burdine (Princeton) and Cecilia Lo (Pittsburgh) for sharing unpublished results and observations. The generous help from Matthias Tisler and Tim Ott in preparing all figures was much appreciated and is gratefully acknowledged. Work in the Blum lab was supported by DFG Grants BL285/9-2 and BL285/10-1 , PV was the recipient of a DFG return fellowship ( VI-574/2-1 ), and CW was supported by NIH R01-GM56238 .
PY - 2014/9/1
Y1 - 2014/9/1
N2 - Asymmetric development of the vertebrate embryo has fascinated embryologists for over a century. Much has been learned since the asymmetric Nodal signaling cascade in the left lateral plate mesoderm was detected, and began to be unraveled over the past decade or two. When and how symmetry is initially broken, however, has remained a matter of debate. Two essentially mutually exclusive models prevail. Cilia-driven leftward flow of extracellular fluids occurs in mammalian, fish and amphibian embryos. A great deal of experimental evidence indicates that this flow is indeed required for symmetry breaking. An alternative model has argued, however, that flow simply acts as an amplification step for early asymmetric cues generated by ion flux during the first cleavage divisions. In this review we critically evaluate the experimental basis of both models. Although a number of open questions persist, the available evidence is best compatible with flow-based symmetry breakage as the archetypical mode of symmetry breakage.
AB - Asymmetric development of the vertebrate embryo has fascinated embryologists for over a century. Much has been learned since the asymmetric Nodal signaling cascade in the left lateral plate mesoderm was detected, and began to be unraveled over the past decade or two. When and how symmetry is initially broken, however, has remained a matter of debate. Two essentially mutually exclusive models prevail. Cilia-driven leftward flow of extracellular fluids occurs in mammalian, fish and amphibian embryos. A great deal of experimental evidence indicates that this flow is indeed required for symmetry breaking. An alternative model has argued, however, that flow simply acts as an amplification step for early asymmetric cues generated by ion flux during the first cleavage divisions. In this review we critically evaluate the experimental basis of both models. Although a number of open questions persist, the available evidence is best compatible with flow-based symmetry breakage as the archetypical mode of symmetry breakage.
KW - Cilia
KW - Ion-flux model
KW - Left-right asymmetry
KW - Leftward flow
KW - Symmetry breakage
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U2 - 10.1016/j.ydbio.2014.06.014
DO - 10.1016/j.ydbio.2014.06.014
M3 - Article
C2 - 24972089
AN - SCOPUS:84905757257
SN - 0012-1606
VL - 393
SP - 109
EP - 123
JO - Developmental Biology
JF - Developmental Biology
IS - 1
ER -