Lineage-specific Cell Communication During Sea Urchin Development

在海胆胚胎中，有五个不变的领域， 谱系-预期的反口外胚层，预期的口 外胚层植物板，成骨间充质和 微小的微粒 除了一种独特的基因模式， 表达式中，这些区域由单个像元定义 谱系历史和不同细胞类型的产生。 的 形成这些领土的血统完全与 第6次切割和空间限制基因 表达式在一个或两个除法之后开始。 在所有 除了骨骼生成间充质，创始细胞 每一个区域的祖先都有独特的模式 通过细胞内的相互作用， 其他细胞。 以下研究旨在确定 内特定细胞类型的创始细胞的谱系和命运 领土;调查具体的功能意义 与邻近细胞的相互作用， 领土;并测试主要信号转导的作用 在领土和细胞类型的规范系统。 的 所提出的实验分为以下几类：1. 笼状荧光素示踪植物板和神经元谱系 葡聚糖 2.细胞谱系和细胞相互作用的研究， 细胞消融 3.异常的分子表征 表型来源于外源血清素配体的引入- 受体系统。 4.异位妊娠的发育后果 刺激PI信号转导系统， 已知谱系的卵裂球（使用血清素受体）。 5. 第二信使水平升高的影响 胚胎和单个卵裂球。 6.发育影响 外源受体激酶在整个胚胎中的表达， 单个细胞。

In the sea urchin embryo there are five territories of invariant lineage - the prospective aboral ectoderm, the prospective oral ectoderm the vegetal plate, the skeletogenic mesenchyme and the small micromeres. In addition to a unique pattern of gene expression, these territories are defined by individual cell lineage histories and generation of distinct cell types. The lineages forming these territories are completely segregated from each other by the 6th cleavage and spatially restricted gene expression begins one or two divisions later. In all the territories except the skeletogenic mesenchyme, the founder cells that are the progenitors of each territory achieve unique patterns of gene expression by means of intracellular interactions with other cells. The following studies are designed to determine the lineage and fate of founder cells for specific cell types within territories; to investigate the specific functional significance of interactions with neighboring cells in establishing certain of the territories; and to test the role of major signal transduction systems in the specification of territories and cell types. The proposed experiments fall into the following categories: 1. Vegetal plate and neuronal lineage tracing with caged flourescein- dextran. 2. Cell lineage and cell interaction studied by means of cell ablation. 3. Molecular characterization of abnormal phenotypes derived from introduction of a foreign serotonin ligand- receptor system. 4. Developmental consequences of ectopic stimulation of the PI signal transduction system in specific blastomeres of known lineage (using the serotonin receptor). 5. The effects of elevated levels of second messengers in whole embryos and individual blastomeres. 6. Developmental effects of the expression of foreign receptor kinases in whole embryos and individual cells.