DORSAL MESODERM FORMATION IN XENOPUS LAEVIS

在发育过程中，多条信号通路和形态发生运动 对胚胎有积极的模式作用。这一过程由渐进的 细胞的特化导致细胞类型的多样性 在成年生物体中。这一过程的第一步是建立 内胚层、中胚层和外胚层 原肠形成。这项研究的总体目标是了解细胞是如何 逐渐致力于某一特定的生殖层。这一知识 将有助于从根本上理解细胞命运是如何 以及它是如何与胚胎的图案相结合的。 该方案研究了细胞的信号和响应机制。 在背侧中胚层诱导期间，导致体节的形成。 第一个特定的目标是检查休眠信号的活性。 它负责指示腹侧中胚层 分化为体细胞组织。体节发育是一个漫长的过程 开始于原肠形成，并继续到神经化，作为 后轴发育。异体移植物将被用于确定 该信号在发育过程中处于活动状态的长度。这将是 揭示这个信号是否在整个递进形成过程中都是活跃的 或者该信号是否仅在体节开始时被激活 队形以启动这一过程。要了解细胞是如何被指示的 为了形成体节，第二个特定目的是检查细胞的行为 移植物细胞和邻近细胞通过延时视频显微照相。这个 第三个特定目的是检查细胞对此作出反应的能力 背靠背信号。初步结果表明，来自神经的细胞 外胚层直到末期仍有能力形成中胚层细胞类型 原肠发育。为了进一步检验这一观察结果，我们将执行 前后神经细胞异种移植的实验研究 外胚层、表皮和腹侧中胚层。我们将研究如何 细胞能力的变化与基因表达的变化以及如何 这共同导致了脊椎动物胚胎的图案化。最后一个目标 就是为学生人数不足的本科生和研究生提供 小组有机会获得基本技能，为他们做好准备 未来在生物医学研究方面的职业生涯。

During development multiple signaling pathways and morphogenetic movements are active to pattern the embryo. This process consists of the progressive specialization of cells to give rise to the diversity of cell types fond in the adult organism. The first step in this process is the establishment of the three embryonic germ layers, endoderm, mesoderm and ectoderm during gastrulation. The overall goal of this research is to understand how cells become progressively committed to a specific germ layer. This knowledge will contribute to the fundamental understanding of how cell fates are established and how it integrates with patterning of the embryo. This proposal examines the signaling and response mechanism of cells during dorsal mesoderm induction which leads to the formation of somites. The first specific aim will examine the activity of the dorsalizing signal which is responsible for instructing ventral-lateral mesoderm to differentiate as somitic tissue. Somite development is a lengthy process that begins at gastrulation and continues into neuralation as the posterior axis develops. Heterochronic grafts will be used to determine the length to which this signal is active during development. This will reveal whether this signal is active throughout the progressive formation of somites or whether this signal is active only at the onset of somite formation to initiate the process. To understand how cells are instructed to form somites, the second specific aim examines the cell behaviors of grafted cells and neighboring cells by time-lapse video micrography. The third specific aim examines the competence of cells to respond to this dorsalizing signal. Preliminary results suggest that cells from the neural ectoderm remain competent to form mesodermal cell types as late as the end of gastrulation. To further examine this observation, we will perform heterochronic grafts of cells from the anterior and posterior neural ectoderm, epidermis and ventral-lateral mesoderm. We will examine how changes in cell competence relate to changes in gene expression and how together this leads to patterning of the vertebrate embryo. The last aim is to provide undergraduate and graduate students from under-represented groups an opportunity to acquire essential skills that will prepare them for future careers in biomedical research.