Cell Lineage in the Developmental Biology of Sea Urchins

海胆早期发育的分子机制必须从胚胎细胞谱系的角度来解释。本研究的目的是进一步探讨细胞谱系关系在海胆胚胎和幼虫发育中的作用。采用多种方法：1)基于现有的部分完成的数据库，一些研究将通过进一步定义最终植物板内的谱系和规格，通过更完整地确定八个小微粒的命运，以及通过描述神经母细胞的起源来解决紫癜胚胎谱系中未解决的问题；2)为了描述调控发育中的谱系变化，一组实验将比较正常谱系模式与经LiCl处理或与微粒融合的离体动物帽细胞的谱系模式，并将比较正常谱系模式与经向四分之一胚胎的谱系模式。3)利用原位杂交技术，对紫斑棘鱼幼体中组织特异性标记基因的表达进行了研究，为紫斑棘鱼幼体形态发生的谱系和特征描述提供依据。发育生物学的一个基本问题是在一个成年人身上发现的各种细胞类型是如何从一个受精卵中衍生出来的。本研究将追踪创始细胞从受精后的早期分裂到最终形成幼虫的细胞命运。它还将探讨决定这些细胞命运的因素。

The molecular mechanisms of early development in the sea urchin must be interpreted in terms of the embryonic cell lineage. The purpose of this investigation is to further explore the role of cell lineage relationships in the development of sea urchin embryos and larvae. A multiple approach is taken: 1) Building on the existing, partially completed database, some studies will address unsolved problems in the lineage of the S. purpuratus embryo by further defining the lineage and specification within the definitive vegetal plate, by determining more completely the fate of the eight small micromeres, and by describing the origins of the neuroblasts; 2) To describe lineage changes in regulative development, a group of experiments will compare normal lineage patterns with the lineage of cells in isolated animal caps treated with LiCl or fused with micromeres and will compare normal lineage patterns with those of meridional quarter embryos, and 3) To provide descriptions of lineage and specification in the morphogenesis of the juvenile echinoderm, the expression of histospecific marker genes in the rudiment of S. purpuratus larvae will be investigated by in situ hybridization. %%% A fundamental problem in developmental biology is how the various cell types found in an adult are derived from a single fertilized egg. This study will trace the cell fates of founder cells from very early divisions after fertilization to their ultimate form in a larvae. It will also explore the factors which determine the fate of those cells.