ORGANIZER AND EMBRYONIC REGULATION

亨森氏结，相当于两栖动物的“斯佩曼氏结” 组织者”，是最重要的区域的非常早期，原肠胚 胚胎它不仅产生了身体的中线器官 （脊索，体节，肠，神经管底板），但也是 负责诱导和塑造整个中枢神经系统 系统经典研究声称，基于形态学标准， 当Hensen结被切除时，脊索和体节正常形成。 该项目包括对这一问题的新调查， 现在可用的许多分子标记的优势，以揭示 将胚胎的这一独特区域指定为“胚胎发育区”的条件是： 组织者”，并将其细胞与原始条纹的其余部分分开。 这项研究将有助于从分子和分子水平上确定组织者。 胚胎学术语，并确定导致 调控该区域中几个基因的表达。最后 结果将显示组织者的哪些属性在 在胚胎发育的早期阶段独立控制。 利用移植实验结合原位杂交和 逆转录病毒载体引起特定基因的错误表达， 具体的问题将被解决：脊索和体节的形式 结消融术后？原始条纹的残端是否表示节点- 淋巴结消融后的特定标记物（例如，goosecoid、sonic hedgehog）？ 消融淋巴结后，原始条纹的残端是否可以获得 神经诱导能力和/或诱导额外手指的能力 寄主肢芽？重新生成的节点是否为左/右不对称（如 正常节点）？重新生成节点属性的能力是否仅限于 原始条纹的特定部分如果上述任何属性 不能被原始条纹获得，它能再生吗？ 这些属性是否表达适当的节点标记基因？

Hensen's node, the amniote equivalent of the amphibian "Spemann's organizer", is the most important region of the very early, gastrulating embryo. Not only does it generate the midline organs of the body (notochord, somites, gut, floor plate of the neural tube), but is also responsible for inducing and patterning the whole of the central nervous system. Classical studies have claimed, based on morphological criteria, that when Hensen's node is ablated, notochord and somites form normally. This project consists of new investigation of this problem, taking advantage of the many molecular markers now available, to reveal the conditions that specify this unique region of the embryo as "the organizer" and set its cells aside from the rest of the primitive streak. The study will help to define the organizer in both molecular and embryological terms and to identify the conditions that lead to the regulation of expression of several genes in this region. Finally, the results will reveal which properties of the organizer are under independent control at very early stages of embryonic development. Using transplantation experiments combined with in situ hybridization and retroviral vectors to cause misexpression of specific genes, the following specific questions will be addressed: Do the notochord and somites form after node ablation? Does the stump of the primitive streak express node- specific markers (e.g. goosecoid, sonic hedgehog) after node ablation? After ablation of the node, can the stump of the primitive streak acquire neural inducing ability and/or the ability to induce extra digits in a host limb bud? Is the regenerated node left/right asymmetric (like the normal node)? Is the ability to regenerate node properties restricted to a specific portion of the primitive streak? If any of the above properties cannot be acquired by the primitive streak, can it be made to regenerate these properties if made to express appropriate node marker genes?