Lineage-specific gene expression in the sea urchin embryo.
Lineage-specific gene expression in the sea urchin embryo.
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海胆胚胎中谱系特异性基因的表达。
DOI：
10.1101/sqb.1985.050.01.041
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Sucov,HM
中科院分区：
文献类型：
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作者：
Davidson,EH;Flytzanis,CN;Lee,JJ;Robinson,JJ;Rose3rd,SJ;Sucov,HM
在受精后的几天内，海胆胚胎发育成一个由大约1800个细胞组成的小型分化生物，能够进食、游泳，并在随后几周的幼虫生长中进行进一步的个体转化。在胚胎发育晚期，可以识别出许多在形态和功能水平上明显特化的不同细胞系，其中许多可以追溯到早期卵裂球的特定组。经典的细胞谱系和实验研究（H6rstadius 1939；回顾，见Angerer和Davidson 1984）已经表明，这些谱系中的某些似乎是特定的，至少部分是由于母系成分遗传在它们的祖细胞占据的卵细胞浆区域。在早期细胞系中对其他细胞系的描述显然取决于卵裂期间卵裂球之间发生的诱导相互作用。对于分子生物学家和他的前辈来说，这种快速发育和简单构造的胚胎提供了实验可及性的优点。因此，就胚胎中基因活性的直接分子水平分析而言，对于特定基因和总体转录种群及其蛋白质产物，海胆是目前最知名的胚胎系统（例如，综述Hentschel和Birnstiel 1981； Davidson等人1982；Angerer和Davidson 1984）。我们实验室最近的工作重点是获得一个克隆基因文库，这些克隆基因在早期胚胎中以谱系特异性的方式表达，用于检查这些基因在发育早期活性的差异指定的分子过程。当然，这是理解受精卵如何产生功能分化胚胎的基本和普遍问题，即使考虑到大多数卵子的细胞质各向异性是公认的（Davidson 1976年回顾）。对于任何胚胎来说，这都是一个远未解决的问题。此外，不同的发展模式完全可以采用不同的解决办法。在下面，我们回顾了目前在分离和鉴定谱系特异性海胆胚胎基因方面的进展，然后简要描述了最近的研究表明，这些基因在显微注射到未受精卵后明显正确地表达。
Within a few days of fertilization, the sea urchin embryo develops into a small differentiated organism consisting of about 1800 cells and capable of feeding, swimming, and the further ontogenic transformations required in the succeeding weeks of larval growth. A number of distinct cell lineages that are clearly specialized at the morphological and functional levels can be discerned in the advanced embryo, and many of these can be traced back to particular sets of early blastomeres. Classical cell lineage and experimental studies (H6rstadius 1939; for review, see Angerer and Davidson 1984) have shown that certain of these lineages appear to be specified, at least in part, in consequence of the maternal components inherited in those regions of egg cytoplasm occupied by their progenitor cells. Specification of others among the early cell lineages clearly depends on inductive interactions that occur between blastomeres during cleavage. For the molecular biologist, as for his predecessors, this rapidly developing and simply constructed embryo offers the advantages of experimental accessibility. Thus, in respect to direct molecular-level analyses of gene activity in the embryo, for both specific genes and overall transcript populations and their protein products, the sea urchin is at present the best known embryonic system (eg, reviews of Hentschel and Birnstiel 1981; Davidson et al. 1982; Angerer and Davidson 1984). A focus of recent efforts in our laboratory has been the acquisition of a library of cloned genes that are expressed in the early embryo in a lineage-specific manner, for use in examination of the molecular processes by which these genes are differentially specified for activity early in development. This is, of course, the fundamental and general problem in understanding how the zygote gives rise to a functionally differentiated embryo, even given the well-established cytoplasmic anisotropy of most eggs (reviewed by Davidson 1976). It is a problem that is far from being solved for any embryo. Furthermore, diverse solutions may well be utilized in different modes of development. In the following, we review current progress on the isolation and characterization of lineage-specific sea urchin embryo genes, and then describe briefly recent studies that demonstrate apparently correct ontogenic expression of such genes after microinjection into the unfertilized egg.