The metabolic process and toxicity mechanism of dietary inorganic arsenic (iAs) in freshwater fish remain unclear to date. The present study conducted two iAs [arsenate (As(V)) and arsenite (As(III))] dietary exposures in freshwater fish crucian carp (Carassius auratus). The fish were fed on As supplemented artificial diets at nominal concentrations of 50 and 100 μg As(III) or As(V) g-1 (dry weight) for 10 d and 20 d. We found that the liver, kidney, spleen, and intestine of fish accumulated more As in As(V) feeding group than that in As(III), while the total As levels in muscle were similar between As(V) and As(III) group at the end of exposure. Reduction of As(V) to As(III) and oxidation of As(III) to As(V) occurred in fish fed with As(V) and As(III), respectively, indicating that toxicity of iAs was likely elevated or reduced when iAs was absorbed by fish before entering into human body through diet. Biomethylation to monomethylarsonic acid and dimethylarsinic acid and transformation to arsenocholine and arsenobetaine were also found in the fish. The linear regression analysis showed a positive correlation between secondary methylation index and the malondialdehyde content in tissues, highlighting the vital role of arsenic dimethylation in the oxidative damages in fish.

中文翻译：

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淡水鱼Car鱼中膳食无机砷的生物转化以及砷二甲基化与氧化损伤之间的独特联系。

迄今尚不清楚淡水鱼中膳食无机砷的代谢过程和毒性机理。本研究在淡水鱼类cru鱼（Car鱼）中进行了两种iAs [砷酸盐（砷（V））和砷酸盐（砷（III））]的饮食。以标称浓度为50和100μg的As（III）或As（V）g-1（干重）的标称浓度的砷为食的鱼饲养10 d和20 d。我们发现鱼的肝，肾，脾和肠在砷（V）喂养组中比砷（III）积累更多的砷，而肌肉中的总砷水平在砷（V）和砷（III）之间相似）小组在曝光结束时。分别饲喂了As（V）和As（III）的鱼体内发生了As（V）还原为As（III）和As（III）氧化为As（V），这表明当鱼通过饮食吸收iAs之前，iAs的毒性可能升高或降低。在鱼中还发现了生物甲基化为单甲基ar磺酸和二甲基ar磺酸，并转化为砷苯甲胆碱和砷甜菜碱。线性回归分析表明，次级甲基化指数与组织中丙二醛含量之间呈正相关，突出了砷二甲基化在鱼类氧化损伤中的重要作用。