Specification of cell fate in the sea urchin embryo: summary and some proposed mechanisms.
Specification of cell fate in the sea urchin embryo: summary and some proposed mechanisms.
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发表时间：
1998-09
期刊：
影响因子：
4.6
通讯作者：
E. Davidson;R. Cameron;A. Ransick
中科院分区：
文献类型：
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作者：
E. Davidson;R. Cameron;A. Ransick
早期的一套卵裂球规格发生在卵裂过程中的海胆胚胎，条件和自主过程的结果，在1989年提出的这个胚胎的模型。最近的实验结果极大地阐明了一些早期胚胎领域的特化机制，尽管其他的仍然模糊不清。我们回顾了特定谱系元素内的规范的渐进过程，并参考早期轴向组织的胚胎。内胚层和其他潜在的卵裂球间信号相互作用的veg2谱系亚元素的条件规范的证据进行了总结。中胚层和内胚层的植物板块之间的边界，以及内胚层和外胚层之间的边界，直到后来的发展，才建立。这些过程已经通过对各种基因的空间表达的大量观察和优雅的谱系标记研究得到了澄清。早期特化事件取决于母体调节因子的区域动员，从而立即导致编码转录因子的基因的合子表达，以及编码细胞类型特征性蛋白质的下游基因的合子表达，所述细胞类型特征性蛋白质将在很久以后从特定卵裂球的后代中产生。这个胚胎显示出间接发育的最大形式。胚胎发育的基因调控网络反映了完整幼虫及其形成所需过程的相对简单性。胚后成人身体计划形成的幼虫雏形的要求包括从事一个新的水平的遗传调控装置，举例说明的Hox基因复合体。
An early set of blastomere specifications occurs during cleavage in the sea urchin embryo, the result of both conditional and autonomous processes, as proposed in the model for this embryo set forth in 1989. Recent experimental results have greatly illuminated the mechanisms of specification in some early embryonic territories, though others remain obscure. We review the progressive process of specification within given lineage elements, and with reference to the early axial organization of the embryo. Evidence for the conditional specification of the veg2 lineage subelement of the endoderm and other potential interblastomere signaling interactions in the cleavage-stage embryo are summarized. Definitive boundaries between mesoderm and endoderm territories of the vegetal plate, and between endoderm and overlying ectoderm, are not established until later in development. These processes have been clarified by numerous observations on spatial expression of various genes, and by elegant lineage labeling studies. The early specification events depend on regional mobilization of maternal regulatory factors resulting at once in the zygotic expression of genes encoding transcription factors, as well as downstream genes encoding proteins characteristic of the cell types that will much later arise from the progeny of the specified blastomeres. This embryo displays a maximal form of indirect development. The gene regulatory network underlying the embryonic development reflects the relative simplicity of the completed larva and of the processes required for its formation. The requirements for postembryonic adult body plan formation in the larval rudiment include engagement of a new level of genetic regulatory apparatus, exemplified by the Hox gene complex.