Blum Martin, Beyer Tina, Weber Thomas, Vick Philipp, Andre Philipp, Bitzer Eva, Schweickert Axel
University of Hohenheim, Institute of Zoology, Stuttgart, Germany.
Dev Dyn. 2009 Jun;238(6):1215-25. doi: 10.1002/dvdy.21855.
Vertebrate organ laterality is manifested by the asymmetric morphogenesis and placement of inner organs. Asymmetric induction of the Nodal signaling cascade in the left lateral plate mesoderm (LPM) precedes and is essential for asymmetric organ morphogenesis. While the Nodal cascade is highly conserved, symmetry breakage is considered to vary between the different classes of the vertebrates. In Xenopus, early determinants at cleavage stages were thought to break symmetry, opposed to cilia-driven leftward flow in mammals and fish. The main objectives of this review are to emphasize the conserved nature of symmetry breakage, and to demonstrate the power of Xenopus embryology to analyze and manipulate flow. In addition, mutant phenotypes described in other model organisms can easily be mimicked in frog by single or multiple knockdowns in combination with experimental manipulations and flow analysis. Xenopus, therefore, is ideally suited to address the major open questions in the field. Developmental Dynamics 238:1215-1225, 2009. (c) 2009 Wiley-Liss, Inc.
脊椎动物器官的左右不对称性表现为内部器官的不对称形态发生和定位。左侧侧板中胚层（LPM）中Nodal信号级联的不对称诱导先于不对称器官形态发生，并且对其至关重要。虽然Nodal级联高度保守，但对称破缺被认为在不同类别的脊椎动物中有所不同。在非洲爪蟾中，卵裂期的早期决定因素被认为会打破对称性，这与哺乳动物和鱼类中由纤毛驱动的向左流动相反。本综述的主要目的是强调对称破缺的保守性质，并展示非洲爪蟾胚胎学在分析和操纵流动方面的作用。此外，通过与实验操作和流动分析相结合的单次或多次基因敲低，其他模式生物中描述的突变表型可以很容易地在青蛙中模拟出来。因此，非洲爪蟾非常适合解决该领域的主要开放性问题。《发育动力学》238:1215 - 1225，2009年。（c）2009年威利 - 利斯公司。
