National Engineering Research Center of Marine Facilities Aquaculture, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, 316022, China.
National Engineering Research Center of Marine Facilities Aquaculture, Marine Science and Technology College, Zhejiang Ocean University, Zhoushan, 316022, China.
Aquat Toxicol. 2020 Jul;224:105480. doi: 10.1016/j.aquatox.2020.105480. Epub 2020 May 3.
The calanoid copepod, Acartia tonsa, is relatively sensitive to marine pollution. Glutathione S-transferase (GST) multifunctional enzyme, as a biomarker, play an important role in detoxification metabolism of exogenous substances. In the present study, GST-theta and GST-mu class homology genes (designated as AtGSTT1 and AtGSTM2) were identified and characterized from A. tonsa. The coding sequence of AtGSTT1 comprised 726 bp and encoded a putative protein of 241 amino acid residues. AtGSTM2 contained an open reading frame of 678 bp that encoded a putative 227 amino acid polypeptide. Both proteins contained a conserved GST-N domain and a GST-C domain. Structural analysis revealed the characteristic N-terminal G-site. Three-dimensional structure analysis showed that AtGSTT1 and AtGSTM2 have two typical domains of GST family: The βαβαββα topology structure at the N- terminus and the superhelical structure at the C- terminus. Subsequently, the expression levels of the two GST genes were detected in A. tonsa using real-time quantitative PCR after exposure to 1,2-dimethylnaphthalene (C2-NAPH) at different concentrations (0.574, 5.736 and 57.358 μg/L) for 24, 48, 72, and 96 h. AtGSTT1 mRNA expression was significantly up-regulated in a time-dependent manner and the highest mRNA expression occurred at 5.736 μg/L C2-NAPH exposure for 96 h. AtGSTM2 mRNA expression peaked at 72 h in 0.574 μg/L and 5.736 μg/L dose groups. The expression level of AtGSTM2 showed an increasing trend in a time-dependent manner at 57.358 μg/L of C2-NAPH. These results suggested that GST genes may play an important role in protecting A. tonsa from C2-NAPH pollution, and provide a theoretical basis for further study on the molecular mechanism of polycyclic aromatic hydrocarbon (PAHs) pollution on zooplankton.
窄腹剑水蚤是一种对海洋污染相对敏感的哲水蚤。谷胱甘肽 S-转移酶（GST）多功能酶作为生物标志物，在对外源物质的解毒代谢中发挥着重要作用。本研究从窄腹剑水蚤中鉴定和表征了 GST-theta 和 GST-mu 类同源基因（分别命名为 AtGSTT1 和 AtGSTM2）。AtGSTT1 的编码序列包含 726bp，编码一个由 241 个氨基酸残基组成的假定蛋白。AtGSTM2 含有一个 678bp 的开放阅读框，编码一个假定的 227 个氨基酸多肽。这两种蛋白质都含有一个保守的 GST-N 结构域和一个 GST-C 结构域。结构分析揭示了特征性的 N 端 G-位点。三维结构分析表明，AtGSTT1 和 AtGSTM2 具有 GST 家族的两个典型结构域：N 端的βαβαββα拓扑结构和 C 端的超螺旋结构。随后，使用实时定量 PCR 检测了两种 GST 基因在 A. tonsa 中的表达水平，方法是在不同浓度（0.574、5.736 和 57.358μg/L）的 1,2-二甲基萘（C2-NAPH）暴露 24、48、72 和 96 h 后。AtGSTT1mRNA 的表达呈时间依赖性显著上调，在 5.736μg/L C2-NAPH 暴露 96 h 时达到最高水平。AtGSTM2mRNA 的表达在 0.574μg/L 和 5.736μg/L 剂量组的 72 h 达到峰值。在 57.358μg/L 的 C2-NAPH 中，AtGSTM2 的表达水平呈时间依赖性增加趋势。这些结果表明，GST 基因可能在保护 A. tonsa 免受 C2-NAPH 污染方面发挥重要作用，为进一步研究多环芳烃（PAHs）污染对浮游动物的分子机制提供了理论依据。
