Gene Analysis of Exogastrula-Inducing Peptides in Sea Urchin Embryo

我们发现，在花青草胚外添加花青草胚间质胚乳时，有一些内在因子可以诱导外泌乳形成。这些因子被命名为胃外瘘诱导肽（EGIPs）。我们对胚胎中EGIPs的生理作用、化学结构和基因表达机制进行了研究。EGIP的生理作用：研究其对胚胎细胞骨架、细胞增殖和细胞外基质的影响。细胞骨架通过微管蛋白和肌动蛋白抗体荧光染色可见。结果表明，EGIP的存在影响了植物板微管和微丝的排列。另一方面，在16细胞期大粒、中粒和卵裂球分离，观察EGIP对各卵裂球增殖的影响。发现外泌乳发生后，只有大粒细胞的分裂被暂时抑制并恢复。EGIP的一级结构：分离出4种具有相似化学结构的EGIP。它们是由53-58个氨基酸残基和6个半胱氨酸残基共同组成的简单肽。测定了4个EGIPs的氨基酸序列，并确定了二硫键的位置。cDNA的合成和基因表达的时机：利用EGIP-D，我们获得了全长为1935 bp的cDNA，接近基因组DNA的总长度。翻译结果表明，4个EGIPs被合成为前体蛋白的大分子，并在胚发育的原胚阶段表达。

We found some intrinsic factors in mesencyme blastulae of Anthocidaris crassispina which induce exogastrulation when added outside the embryos. This factors were named exogastrula-inducing peptides (EGIPs). We have investigated the physiological actions, the chemical structure and the mechanisms of of gene expression of EGIPs in the embryos.1. Physilolgical actions of EGIP : We studies the effects on cytoskeletones, cell proliferation and extracellular matrix of embryos. Cytoskeletones were visualized by fluorecent stainings with antibodies for tubulin and actin. It was suggested that the arrangements of microtubules and microfilaments in vegital plates were affected by the presence of EGIP. On the other hand, macromeres, mesomeres and were separate in 16-cell stage and the effects of EGIP on the proliferation of each blastomeres were observed. It was found that the cell divisions of only macromeres were temporarily inhibited and restored on onset of exogastrulation.2. Primary structures of EGIP : 4 Kinds of EGIP were isolated which have some similarities in chemical structures. They are simple peptides which are composed of 53-58 amino acid residues and 6 cysteine residues in common. The amino acid sequences of 4 EGIPs were all determined and the position of disulfide bonds were also settled.3. Synthesis of cDNA and the timing of gene expression : Using EGIP-D, we obtained cDNA with 1935 bp near almost total length of genomic DNA. As a result of translation of the cDNA, it revealed that 4 EGIPs were synthesized as a huge molecule of a precursor protein and expressed in gastrula stage of empryo development.