Zinc transporters play vital roles in regulating zinc content and localization by mobilizing zinc across cellular and intracellular membranes. Pacific oyster Crassostrea gigas is one of the most zinc-rich animals, which has been regarded as an excellent food for zinc supplement. But the information about zinc transporters and their involvements in zinc accumulation in oysters is still limited. In the present study, a total of 28 zinc transporter genes, including nine Zinc transporter genes (CgZnTs) and 19 Zrt/Irt-like protein genes (CgZIPs), were identified in C. gigas genome using a genome-wide search strategy. There were five ZIP10 homologs in C. gigas, which were much more than those in mammals, fish and other mollusks. Among oyster zinc transporters, immense variations were detected in their gene structure, protein length and physicochemical properties. Phylogenetic analysis showed that most of these transporters were distinctly clustered with their homologs from Homo sapiens, Danio rerio and other mollusks, and the most closely related transporters shared similar motif compositions. The highest zinc content was detected in the oyster mantle and gill, while the lowest level was found in the adductor muscle. The mRNA of all tested CgZnTs and CgZIPs were constitutively expressed in oyster tissues, and most of them were highly expressed in the gill or hepatopancreas. The analysis of RNA-seq data from gill and hepatopancreas showed that all the transporters exhibited divergent response patterns under zinc stress, except for CgZIP4 whose expression was almost undetectable in the two tissues. The results indicated that zinc transporters played important roles in the regulation of zinc homeostasis in C. gigas, which provided a solid foundation for further functional analysis of zinc transporters in oysters and other mollusks.

中文翻译：

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锌转运蛋白参与太平洋牡蛎Crassostrea gigas中锌的积累。

锌转运蛋白通过在细胞膜和细胞内膜上动员锌，在调节锌含量和定位中起着至关重要的作用。太平洋牡蛎Crassostrea gigas是最富锌的动物之一，被认为是补锌的极好食物。但是关于锌转运蛋白及其参与牡蛎锌积累的信息仍然有限。在本研究中，使用全基因组搜索策略在长形隐孢子虫基因组中鉴定出总共28个锌转运蛋白基因，其中包括9个锌转运蛋白基因（CgZnTs）和19个Zrt / Irt样蛋白基因（CgZIPs）。C. gigas中有五个ZIP10同源物，比哺乳动物，鱼类和其他软体动物中的同源物更多。在牡蛎锌转运蛋白中，发现其基因结构存在巨大差异，蛋白质长度和理化特性。系统发生分析表明，大多数这些转运蛋白与来自智人，达尼奥·里奥和其他软体动物的同源物明显地聚在一起，并且最密切相关的转运蛋白具有相似的基序组成。在牡蛎地幔和g中检测到最高的锌含量，而在内收肌中发现最低的锌含量。所有测试的CgZnT和CgZIP的mRNA在牡蛎组织中组成性表达，并且大多数在most或肝胰腺中高度表达。对来自ill和肝胰腺的RNA-seq数据的分析表明，除CgZIP4几乎在两个组织中均未检测到表达外，所有转运蛋白在锌胁迫下均表现出不同的响应模式。