Silver (Ag) and cadmium (Cd) are non-essential metals that, as a result of natural processes and human activities, reach the aquatic environment where they interact with biota inducing potential toxic effects. To determine the biological effects of these metals on the endobenthic bivalve Scrobicularia plana, specimens were exposed to Ag and Cd at two concentrations, 5 and 50 μg∙L-1, for 7 days in a controlled microcosm system. The levels of the metals were measured in the seawater, sediments and clam tissues. The possible toxic biological effects of Ag and Cd were studied using a battery of biochemical biomarkers that are responsive to oxidative stress: superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione-S-transferase (GST) activities, and metallothioneins (MTs) and lipid peroxidation (LPO) levels. Since both metals have been linked to oxidative stress, redox modifications to proteins were studied by differential isotopic labelling of the oxidised and reduced forms of cysteines (Cys). An accumulation of metals was observed in the digestive gland and gills following exposure, together with the activation of enzyme activities (SOD for the Cd exposure; SOD, CAT, GST, and GR for the Ag exposure). The MT and LPO levels (after individual exposure to Ag and Cd) increased, which suggests the existence of antioxidant and detoxification processes to mitigate the toxic oxidative effects of both metals. The redox proteomic analysis identified 771 Cys-containing peptides (out of 514 proteins), of which 195 and 226 changed after exposure to Ag and Cd, respectively. Bioinformatics analysis showed that exposure to metal affects relevant functional pathways and biological processes in S. plana, such as: “cellular respiration” (Ag), “metabolism of amino acids” and “synthesis and degradation of proteins” (Ag and Cd), “carbohydrate metabolism” and “oxidative stress” (Cd). The proteomic approach implemented here is a powerful complement to conventional biochemical biomarkers, since it evaluates changes at the protein level in a high-throughput unbiased manner, thus providing a general appraisal of the biological responses altered by exposure to the contaminants.

中文翻译：

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Ag 和 Cd 促进的氧化还原蛋白质组在穴位双壳类 Scrobicularia plana 中的积累、生化反应和变化


银 （Ag） 和镉 （Cd） 是非必需金属，由于自然过程和人类活动，它们会到达水生环境，在那里它们与生物群相互作用，从而产生潜在的毒性作用。为了确定这些金属对底栖双壳类 Scrobicularia plana 的生物学效应，将标本暴露在 5 μg∙L-1 两种浓度的 Ag 和 Cd 中 7 天，在受控的微观系统中。测量了海水、沉积物和蛤蜊组织中的金属含量。使用一组对氧化应激有反应的生化生物标志物研究了 Ag 和 Cd 可能的毒性生物学效应：超氧化物歧化酶 （SOD）、过氧化氢酶 （CAT）、谷胱甘肽还原酶 （GR）、谷胱甘肽-S-转移酶 （GST） 活性，以及金属硫蛋白 （MT） 和脂质过氧化 （LPO） 水平。由于这两种金属都与氧化应激有关，因此通过半胱氨酸 （Cys） 的氧化和还原形式的差异同位素标记来研究蛋白质的氧化还原修饰。暴露后在消化腺和鳃中观察到金属的积累，以及酶活性的激活（Cd 暴露的 SOD;SOD、CAT、GST 和 GR 用于 Ag 暴露）。MT 和 LPO 水平（个体暴露于 Ag 和 Cd 后）增加，这表明存在抗氧化和解毒过程以减轻这两种金属的毒性氧化作用。氧化还原蛋白质组学分析鉴定了 771 种含 Cys 的肽（在 514 种蛋白质中），其中 195 种和 226 种在暴露于 Ag 和 Cd 后分别发生了变化。生物信息学分析表明，暴露于金属会影响 S 中的相关功能途径和生物过程。 平面，例如：“细胞呼吸”（Ag）、“氨基酸的代谢”和“蛋白质的合成和降解”（Ag 和 Cd）、“碳水化合物代谢”和“氧化应激”（Cd）。这里实施的蛋白质组学方法是对传统生化生物标志物的有力补充，因为它以高通量无偏倚的方式评估蛋白质水平的变化，从而对因暴露于污染物而改变的生物反应进行一般评估。