Extracellular Matrix Induction of Primary Mesenchyme Differention

海胆微粒在胚胎的营养极通过四个细胞的营养层不同程度的分裂而产生。初级间充质是微粒的切割产物，它们迁移到胚胎的囊胚中，在那里它们与细胞外基质(ECM)相互作用，并分化形成胚胎骨架或针状体。来自体外和体内研究的证据表明，微体需要一个允许的环境或信号来启动分化。一个完整的胚胎ECM是许可环境的主要组成部分。PI最近表明，如果在重建的基膜(Matrigel)上培养，微体将在体外分化。单独在海水中培养的微粒子不会分化。基质中启动分化的分子是什么，它与胚胎中的内源信号分子有何关系。PI建议：(1)从海胆胚胎中鉴定和纯化针状体诱导活性(SIA)；(2)表征SIA的一般作用机制；(3)鉴定和鉴定海胆胚胎中的同源SIA活性。

Sea urchin micromeres arise at the vegetal pole of the embryo by unequal cleavage in the vegetal tier of four cells. Primary mesenchyme, the cleavage products of the micromeres, migrate into the blastocoel of the embryo where they interact with the extracellular matrix (ECM) and differentiate to produce the embryonic skeleton or spicule. Evidence from in vitro and in vivo studies suggests that the micromeres require a permissive environment or signal to initiate differentiation. An intact embryonic ECM is a major component of the permissive environment. The PI has recently shown that micromeres will differentiate in vitro if cultured on a reconstituted basal lamina (matrigel). Isolated micromeres cultured in sea water alone will not differentiate. What is the molecule in the matrigel which initiates differentiation and how is it related to the endogenous signalling molecule in the embryo. The PI proposes to: (1) identify and purify the spicule inducing activity (SIA) from the matrigel, (2) characterize the general mechanism of action of SIA, and (3) identify and initiate characterization of the homologous SIA activity from the sea urchin embryo.