This study provides a preliminary characterization of a metallothionein (MT) gene in Septifer virgatus and highlights its potential use in biomonitoring. The full-length SvMT cDNA and the complete sequence of the SvMT gene were identified using reverse transcriptase PCR coupled with the rapid amplification of cDNA ends and the primer walking method. The SvMT cDNA encodes a protein of 72 amino acids having nine classical Cys-X-Cys motifs. Moreover, the deduced amino acids contained the conserved motif (Cys–x–Cys–x(3)–Cys–Thr–Gly–x(3)–Cys–x–Cys–x(3)–Cys–x–Cys–Lys) of MT family 2. Its molecular mass and isoelectric point were estimated to be 7.01 kDa and 7.00, respectively. BLAST-based searching indicated that SvMT shared 81.0% amino acid sequence identity with Mytilus edulis MT-20-II. The SvMT gene has three coding exons and two introns. After exposure to 1 mg/L cadmium chloride, the expression of SvMT increased 15-fold by 3 days (d), with a maximum expression of 27-fold by 5 d compared with the pre-exposure level. After exposure to 2 mg/L zinc chloride, the expression of SvMT increased 2.5-fold by 3 d and 4.7-fold by 5 d compared with the pre-exposure level. A significant increase in the expression level of SvMT mRNA was observed after the exposure of S. virgatus to the combination of 0.003 mg/L cadmium chloride and 0.2 mg/L zinc chloride compared with the pre-exposure level. Our work indicates that the SvMT gene is associated with stress responses and could be a potential biomarker for marine pollution.

中文翻译：

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来自 Septifer virgatus 的金属硫蛋白基因的分子鉴定、表征和表达分析。

这项研究提供了Septifer virgatus 中金属硫蛋白 ( MT ) 基因的初步特征，并强调了其在生物监测中的潜在用途。使用逆转录酶 PCR 结合 cDNA 末端的快速扩增和引物步移法鉴定全长SvMT cDNA 和SvMT基因的完整序列。该SvMTcDNA 编码具有 9 个经典 Cys-X-Cys 基序的 72 个氨基酸的蛋白质。此外，推导的氨基酸含有保守基序（Cys-x-Cys-x(3)-Cys-Thr-Gly-x(3)-Cys-x-Cys-x(3)-Cys-x-Cys- Lys) 属于 MT 家族 2。其分子量和等电点估计分别为 7.01 kDa 和 7.00。基于BLAST的搜索表明SvMT与Mytilus edulis MT-20-II具有81.0%的氨基酸序列同一性。该SvMT基因有三个编码外显子和两个内含子。暴露于 1 mg/L 氯化镉后，SvMT的表达在 3天时增加了 15 倍（d），与暴露前水平相比，在 5 天时最大表达量增加了 27 倍。暴露于 2 mg/L 氯化锌后，SvMT的表达与暴露前水平相比，3 d 增加 2.5 倍，5 d 增加 4.7 倍。暴露于S后观察到SvMT mRNA的表达水平显着增加。雀鹰与预曝光水平相比的0.003毫克/升氯化镉和0.2mg / L氯化锌的组合。我们的工作表明SvMT基因与应激反应有关，可能是海洋污染的潜在生物标志物。