Cryptocaryon irritans is a fatal parasite for marine teleosts and causes severe economic loss for aquaculture. Galvanized materials have shown efficacy in controlling this parasite infestation through the release of zinc ions to induce oxidative stress. In this study, the resistance mechanism in C. irritans against oxidative stress induced by zinc ions was investigated. Untargeted metabolomics analysis was used to determine metabolic regulation in C. irritans in response to zinc ion treatment by the immersion of protomonts in ZnSO4 solution at a sublethal dose (20 μmol). Eight differential metabolites were selected to assess the efficacy of defense against zinc ion stimulation in protomonts of C. irritans. Furthermore, the mRNA relative levels of glutathione metabolism-associated enzymes were measured in protomonts following treatment with ZnSO4 solution at sublethal dose. The results showed that zinc ion exposure disrupted amino acid metabolism, carbohydrate metabolism, lipid metabolism, and nucleotide metabolism in C. irritans. Four antioxidants, namely ascorbate, S-hexyl-glutathione, syringic acid, and ubiquinone-1, were significantly increased in the Zn group (P < 0.01), while the glutathione metabolism pathway was enhanced. The encystment rate of C. irritans was significantly higher in the ascorbate and methionine treatment (P < 0.05) groups. Additionally, at 24 h post-zinc ion exposure, the relative mRNA level of glutathione reductase (GR) was increased significantly (P < 0.01). On the contrary, the relative mRNA levels of glutathione S-transferase (GT) and phospholipid-hydroperoxide glutathione peroxidase (GPx) were significantly decreased (P < 0.05), thus indicating that the generation of reduced glutathione was enhanced. These results revealed that glutathione metabolism in C. irritans contributes to oxidative stress resistance from zinc ions, and could be a potential drug target for controlling C. irritans infection.

中文翻译：

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刺激白点虫中的谷胱甘肽代谢参与防御锌离子诱导的氧化应激

Cryptocaryon irritans 是海洋硬骨鱼的致命寄生虫，对水产养殖造成严重的经济损失。镀锌材料已显示出通过释放锌离子诱导氧化应激来控制这种寄生虫感染的功效。在这项研究中，研究了 C. irritans 对锌离子诱导的氧化应激的抗性机制。非靶向代谢组学分析用于通过将 protomonts 以亚致死剂量 (20 μmol) 浸入 ZnSO4 溶液中来确定刺激 C. irritans 响应锌离子处理的代谢调节。选择了八种不同的代谢物来评估在 C. irritans 的 protomonts 中对锌离子刺激的防御效果。此外，在用亚致死剂量的 ZnSO4 溶液处理后，在 protomonts 中测量了谷胱甘肽代谢相关酶的 mRNA 相对水平。结果表明，锌离子暴露会破坏 C. irritans 的氨基酸代谢、碳水化合物代谢、脂质代谢和核苷酸代谢。锌组中抗坏血酸、S-己基-谷胱甘肽、丁香酸和泛醌-1四种抗氧化剂含量显着增加（P < 0.01），而谷胱甘肽代谢途径增强。抗坏血酸和蛋氨酸处理组的 C. irritans 包囊率显着升高（P < 0.05）。此外，在锌离子暴露后 24 小时，谷胱甘肽还原酶 (GR) 的相对 mRNA 水平显着增加 (P < 0.01)。相反，谷胱甘肽S-转移酶（GT）和磷脂-氢过氧化物谷胱甘肽过氧化物酶（GPx）的相对mRNA水平显着降低（P < 0.05），表明还原型谷胱甘肽的生成增强。这些结果表明，C. irritans 中的谷胱甘肽代谢有助于抵抗锌离子的氧化应激，并且可能是控制 C. irritans 感染的潜在药物靶点。