Ciliation and gene expression distinguish between node and posterior notochord in the mammalian embryo
Ciliation and gene expression distinguish between node and posterior notochord in the mammalian embryo
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DOI：
10.1111/j.1432-0436.2006.00124.x
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发表时间：
2007-02-01
期刊：
影响因子：
2.9
通讯作者：
Viebahn, Christoph
中科院分区：
文献类型：
--
作者：
Blum, Martin;Andre, Philipp;Viebahn, Christoph
哺乳动物的淋巴结，功能相当于青蛙的背囊胚口唇（Spemann's organizer），最初由Viktor Hensen于1876年在兔胚胎中描述为原始条纹前端的细胞团。今天，术语“节点”通常用于描述一个双层上皮沟，在小鼠卵柱的远端呈现为一个凹陷或“坑”，其腹侧的纤毛负责分子侧性（左-右）确定。我们发现，在兔子的亨森氏结是缺乏纤毛，纤毛细胞仅限于脊索板，出现从节点吻。在一个比较的方法，我们使用的组织者标记基因Goosecoid（GSC）显示，一个密集的上皮样细胞的区域在前端的原始条纹代表节点在小鼠和兔，并覆盖腹侧由下胚层（称为“内脏内胚层”的小鼠）。Nodal是一种复杂地参与决定脊椎动物偏侧性的基因，其表达描绘了兔和小鼠脊索的宽板状后段，在小鼠中，其由通常被称为“结节”的凹陷表示。“类似的特征性纤毛和结节表达存在于爪蟾神经胚的胃腔顶板（GRP）中，即，在胚囊口唇前面的脊索的后端。我们的数据表明：（1）脊索的后段，这里称为PNC（后脊索），其特征在于已知参与侧化决定的特征，（2）非洲爪蟾的GRP与哺乳动物的PNC相当，（3）由组织者基因表达定义的哺乳动物淋巴结缺乏纤毛，很可能不直接参与侧化决定。
The mammalian node, the functional equivalent of the frog dorsal blastoporal lip (Spemann's organizer), was originally described by Viktor Hensen in 1876 in the rabbit embryo as a mass of cells at the anterior end of the primitive streak. Today, the term "node" is commonly used to describe a bilaminar epithelial groove presenting itself as an indentation or "pit" at the distal tip of the mouse egg cylinder, and cilia on its ventral side are held responsible for molecular laterality (left-right) determination. We find that Hensen's node in the rabbit is devoid of cilia, and that ciliated cells are restricted to the notochordal plate, which emerges from the node rostrally. In a comparative approach, we use the organizer marker gene Goosecoid (Gsc) to show that a region of densely packed epithelium-like cells at the anterior end of the primitive streak represents the node in mouse and rabbit and is covered ventrally by a hypoblast (termed "visceral endoderm" in the mouse). Expression of Nodal, a gene intricately involved in the determination of vertebrate laterality, delineates the wide plate-like posterior segment of the notochord in the rabbit and mouse, which in the latter is represented by the indentation frequently termed "the node." Similarly characteristic ciliation and nodal expression exists in Xenopus neurula embryos in the gastrocoel roof plate (GRP), i.e., at the posterior end of the notochord anterior to the blastoporal lip. Our data suggest that (1) a posterior segment of the notochord, here termed PNC (for posterior notochord), is characterized by features known to be involved in laterality determination, (2) the GRP in Xenopus is equivalent to the mammalian PNC, and (3) the mammalian node as defined by organizer gene expression is devoid of cilia and most likely not directly involved in laterality determination.