Evolution of the teleostean zona pellucida gene inferred from the egg envelope protein genes of the Japanese eel, Anguilla japonica
Evolution of the teleostean zona pellucida gene inferred from the egg envelope protein genes of the Japanese eel, Anguilla japonica
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DOI：
10.1111/j.1742-4658.2010.07874.x
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发表时间：
2010-11-01
期刊：
影响因子：
5.4
通讯作者：
Yasumasu, Shigeki
中科院分区：
文献类型：
--
作者：
Sano, Kaori;Kawaguchi, Mari;Yasumasu, Shigeki
鱼卵被膜由几种糖蛋白组成，称为透明质酸（ZP）蛋白，它们在脊椎动物中是保守的。真骨鱼类在肝脏中合成ZP蛋白，而耳首鱼类在生长的卵母细胞中合成它们。我们研究了ZP蛋白的日本鳗鱼，日本鳗鲡，属于Elopomorpha，其中分化早于真骨和耳头。对卵膜的5种主要成分进行了纯化，并测定了它们的部分氨基酸序列。cDNA克隆结果表明，鳗鱼卵被膜由4个ZPC同源物和1个ZPB同源物组成。四个鳗鱼ZP（eZP）蛋白具有跨膜结构域，这是没有发现的ZP蛋白的真骨鱼和耳头鱼的分歧后，但在大多数其他脊椎动物ZP蛋白。这一结果表明，鱼类ZP蛋白最初具有跨膜结构域，并在进化过程中失去了它。北方杂交和RT-PCR结果表明，eZP基因在卵巢中均有表达，但在肝脏中没有表达。鱼类zp基因的系统发育分析表明，ezps形成了一组与其他鱼类zp基因表达在卵巢中，这是不同于组的基因表达在肝脏中。我们的研究结果支持这一假设，即鱼ZP蛋白最初在卵巢合成，然后合成的网站切换到肝脏的进化过程中真骨鱼类。
A fish egg envelope is composed of several glycoproteins, called zona pellucida (ZP) proteins, which are conserved among vertebrate species. Euteleost fishes synthesize ZP proteins in the liver, while otocephalans synthesize them in the growing oocyte. We investigated ZP proteins of the Japanese eel, Anguilla japonica, belonging to Elopomorpha, which diverged earlier than Euteleostei and Otocephala. Five major components of the egg envelope were purified and their partial amino acid sequences were determined by sequencing. cDNA cloning revealed that the eel egg envelope was composed of four ZPC homologues and one ZPB homologue. Four of the five eel ZP (eZP) proteins possessed a transmembrane domain, which is not found in the ZP proteins of Euteleostei and Otocephala that diverged later, but is found in most other vertebrate ZP proteins. This result suggests that fish ZP proteins originally possessed a transmembrane domain and lost it during evolution. Northern blotting and RT-PCR revealed that all of the eZP transcripts were present in the ovary, but not in the liver. Phylogenetic analyses of fish zp genes showed that ezps formed a group with other fish zp genes that are expressed in the ovary, and which are distinct from the group of genes expressed in the liver. Our results support the hypothesis that fish ZP proteins were originally synthesized in the ovary, and then the site of synthesis was switched to the liver during the evolutionary pathway to Euteleostei.