CELL SURFACE AND MATRIX PROTEINS IN LIMB DEVELOPMENT

形式和模式出现在脊椎动物胚胎发育过程中， 细胞在特定的空间和时间限制下分化 通过相互的组织相互作用。 这项研究的核心是 假设这种相互作用部分是由独特的 细胞表面和细胞外蛋白。 我们计划验证这个假设 使用发育中的鸟类肢体。 具体而言，本研究的目的是 鉴定和表征细胞外和细胞表面蛋白， （i）局限于肢芽的特定区域，（ii）与 它们出现的时间与关键形态发生事件和（iii） 受到破坏肢体形态发生的突变的影响。 相遇的蛋白质 这些标准很可能是形态发生的控制因素。 细胞表面和基质蛋白将在（1）中进行鉴定和比较。 未定型的、增殖的肢体中胚层与分化近端 在正常胚胎和talpid 2突变体中的中胚层， 多并趾肢，（2）诱导活跃的顶端外胚层嵴; 来自正常胚胎的无嵴外胚层和来自暂时肢的外胚层 无肢突变体的芽不能形成顶脊。 蛋白 将在体内用35S-甲硫氨酸、3H-岩藻糖或 32 p-正磷酸盐和细胞表面和基质蛋白以及糖蛋白 将在体外用125I/Iodogen选择性标记，或 3H-硼氢化物/高碘酸盐。 细胞外、细胞表面和质膜 蛋白质将通过选择性酶消化 完整组织，通过选择性溶解和质膜 隔离 我们相信无肢和高脚的变种人 优秀的模型系统，用于分析遗传性肢体缺陷， 高等生物，细胞表面的特征和 正常和突变肢体发育中的细胞外蛋白质 大大增强了我们对组织分子基础的理解 交互. 我们希望这些研究将有助于更好地 了解人类先天性肢体缺陷。

Form and pattern arise during vertebrate embryogenesis because groups of cells differentiate under specific spatial and temporal constraints imposed by reciprocal tissue interactions. Central to this research is the hypothesis that such interactions are mediated in part by unique sets of cell surface and extracellular proteins. We plan to test this hypothesis using the developing avian limb. Specifically, the aim of this research is to identify and characterize extracellular and cell surface proteins that are (i) restricted to specific regions of the limb bud, (ii) correlated in the time of their appearance with key morphogenetic events and (iii) affected by mutations that disrupt limb morphogenesis. Proteins that meet these criteria are very likely to be controlling factors in morphogenesis. Cell surface and matrix proteins will be identified and compared in (1) uncommitted, proliferating limb mesoderm vs. differentiation proximal mesoderm in normal embryos and in talpid2 mutants which form polysyndactylous limbs, (2) inductively active apical extodermal ridge vs. non-ridge extoderm from normal embryos and ectoderm from the transient limb buds of limbless mutants which fails to form an apical ridge. Proteins will be labeled in vivo with 35S-methionine, 3H-fucose or 32p-orthophosphate and cell surface and matrix proteins and glycoproteins will be selectively labeled in vitro with 125I/lodogen or 3H-borohydride/periodate. Extracellular, cell surface and plasma membrane proteins will be further distinguished by selective enzymatic digestion of intact tissues, by selective solubilization and by plasma membrane isolation. We believe that the limbless and talpid mutants provide excellent model systems for the analysis of inherited limb defects in higher organisms and that the characterization of cell surface and extracellular proteins in both normal and mutant limb development will significantly enhance our understanding of the molecular bases of tissue interactions. We hope that these studies will conribute to a better understanding of human congenital limb defects.