GENE EXPRESSION IN EARLY EMBRYONIC DEVELOPMENT

这项提议的广泛目标是了解细胞如何在 发育中的胚胎带来决定和分化。 全能卵子的后代对不同种类的 发育中胚胎的分化途径是一个基本的生物学问题 最重要的问题。单元格做出的选择遵循不同的 途径是正常和不正常胚胎发育的中心， 癌症，会修复，会衰老。这些实验将集中在海洋上。 海胆胚胎，一个与脊椎动物非常相似的系统，依赖于 细胞相互作用作为一种确定各种 早期发育中的细胞类型和谱系。这个胚胎有各种各样的 可以彼此分离并重组的卵裂球 不同的方式。新的组织特异性标志物作为可靠的 具体分化途径的指标现已可用。 首先，这些标记将被用来学习管理规则 特定的基因表达。这将涉及实验，在其中 单个卵裂球单独培养或与其他 卵裂球类型，或与各种试剂(如锂离子，成纤维细胞生长因子)。命运 卵裂球和各种基因的表达 原位杂交和免疫细胞化学。有本地化的吗 卵子植物半球中的物质，它们启动 形成肠道和针状体的谱系：有没有离子或激动剂 可能会有效地导致动物细胞的植物分化？ 这些代理人是否使用第二信使途径来影响他们的 行为?第二，开发和表征特定组织的努力 将继续进行cdna克隆。这些努力将集中在克隆上。 针状体基质基因，以及仅在其后代中表达的基因 系膜。第三，针状体基质基因如何表达的细节 是否受到监管将被研究。这些基因的转录将是 在体外对转录定义的核提取物进行研究 模板。这一功能分析将被用于对 启动子活性和研究蛋白质所需的DNA序列 与DNA相互作用的提取物。

The broad objective of this proposal is to learn how cells interact in the developing embryo to bring about determination and differentiation. the commitment of the progeny of a totipotent ovum to the various differentiation pathways of the developing embryo is a basic biological problem of prime importance. Choices made by cells to follow different paths are central to normal and abnormal embryonic development, to cancer, would repair, and aging. The experiments will focus on the sea urchin embryo, a system very similar to vertebrates in its reliance on cell interactions as a way of bringing about determination of various cell types and lineages in early development. This embryo has various blastomeres that can be separated form one another and recombined in various ways. New tissue specific markers that serve as reliable indicators of specific differentiation pathways are now available. first, these markers will be used to learn the rules that govern specific gene expression. This will involve experiments in which individual blastomeres are cultured alone or in combination with other blastomere types, or with various agents (e.g., Li ion, FGF). The fate of the blastomeres and expression of various genes will be measured by in situ hybridization and immunocytochemistry. Are there localized substances in the vegetal hemisphere of the egg that initiate the lineages that form gut and spicules: Are there ions or agonists that might be effective in causing vegetal differentiation of animal cells? Do these agents use secondary messenger pathways to effect their actions? Second, the effort to develop and characterize tissue specific cDNA clones will be continued. The efforts will concentrate on cloning spicule matrix genes, and on genes expressed solely in descendants of mesomeres. Third, the details of how expression of spicule matrix genes is regulated will be studied. Transcription of these genes will be studied, in vitro, in nuclear extracts that transcribe defined templates. This functional assay will be used to conduct studies on the DNA sequences necessary for promoter activity and to study proteins in the extracts that interact with the DNA.