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Study on the cytoplasmic and inductive factors for the excitable membrane differentiation in the cleavage-arrested and isolated blastomeres of the early embryo.

早期胚胎卵裂停滞和分离卵裂球可兴奋膜分化的细胞质和诱导因子的研究。

基本信息

批准号：
60480115
负责人：
TAKAHASHI Kunitaro
金额：
$ 4.16万
依托单位：
Faculty of Medicine, University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

项目摘要

As previously reported, when the cell-cleavage of the Halocynthia embryo of the protochordate is arrested at the early developmental stage, such as 1- to 8-cell, and the arrested embryo is cultured further until the normal hatching time, the membrane of a large and multinuclear blastomere expresses one of four types of excitability, such as neural, epidermal, muscular and non-excitable types. This suggests that all nuclei in the blastomere apparently select only one cell type for their expression though the blastomere has multiple fates during normal development. In this research project, this selection is presumed to be one of the important mechanisms for cellular differentiation in general. Following two kinds of experiments were performed. Firstly, the cell autonomous differentiation of the isolated and cleavage-arrested blastomeres of the 8-cell was studied. Secondly the differentiation under the interaction with neighboring cells was studied by contacting two types of the blastomere during development. The anterior a42 and posterior b42 ectodermal blastomeres of the 8-cell evoked a long-lasting Ca action potential and antiepidermal monoclonal antibody 2C5 was bound to their cytoplasm, suggesting the epidermal type differentiation when they were cultured in isolated condition. In contrast, the a42's produced Na spikes in 70% of all examined cases when they were cultured under close contact with the A41 blastomere. In this situation the 2C5 was not bound to the cytoplasm, suggesting the differentiation other than the epidermal type. Considering that in the case of vertebrate embryo's the axial mesoderm including the presumptive notochordal region can induce the neural plate, in this protochordate, an ancestoral form of the vertebrate, the a42 including presumptive brain vesicle region was inferred to be induced by the A41 including the presumptive notochordal region and to differentiate into neural type.

如前所述，当原脊索动物Halocynthia胚胎的细胞分裂在发育早期（如1- 8细胞）被阻止时，被阻止的胚胎进一步培养直到正常孵化时间，一个大的多核囊胚的膜表达四种类型的兴奋性，如神经型，表皮型，肌肉型和非兴奋型。这表明，尽管卵裂球在正常发育过程中有多种命运，但所有的细胞核显然只选择一种细胞类型来表达。在本研究项目中，这种选择被认为是细胞分化的重要机制之一。进行了以下两种实验。首先，研究了8细胞分离的卵裂球和卵裂阻滞的细胞自主分化。其次，通过接触两种类型的卵裂球，研究其在发育过程中与邻近细胞相互作用下的分化情况。8细胞外胚层卵裂球前a42和后b42激发了持久的Ca动作电位，胞质上结合了抗表皮单克隆抗体2C5，表明在离体培养条件下已向表皮型分化。相比之下，当a42与A41卵裂球密切接触时，在所有检测病例中，有70%的a42产生了Na峰值。在这种情况下，2C5不与细胞质结合，提示分化为非表皮型。考虑到脊椎动物胚胎的轴向中胚层包括推定脊索区可以诱导神经板，在该脊椎动物的祖先形式原脊索动物中，推断包括推定脑泡区的a42是由包括推定脊索区的A41诱导并分化为神经型的。