Abstract：
The speciation of arsenic in fish has been widely investigated, but bioaccumulation and biotransformation of inorganic As in different tissues of Nile tilapia (Oreochromis niloticus) are not fully understood. The present study aimed to investigate the bioaccumulation of As in Nile tilapia, as well as to evaluate the distribution of the main arsenic species (As(III), As(V), MMA, DMA, and AsB) in liver, stomach, gill, and muscle, after controlled exposures to As(III) and As(V) at concentrations of 5.0 and 10.0 mg L-1 during periods of 1 and 7 days. Total As was determined by inductively coupled plasma mass spectroscopy (ICP-MS). For both exposures (As(III) and As(V)), the total As levels after 7-day exposure were highest in the liver and lowest in the muscle. Overall, the Nile tilapia exposed to As(III) showed higher tissue levels of As after the treatments, compared to As(V) exposure. Speciation of arsenic present in the tissues employed liquid chromatography coupled to ICP-MS (LC-ICP-MS), revealing that the biotransformation of As included As(V) reduction to As(III), methylation to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), and subsequent conversion to nontoxic arsenobetaine (AsB), which was the predominant arsenic form. Finally, the interactions and antagonistic effects of selenium in the bioaccumulation processes were tested by the combined exposure to As(III), the most toxic species of As, together with tetravalent selenium (Se(IV)). The results indicated a 4-6 times reduction of arsenic toxicity in the tilapia.
摘要：
鱼类中砷的形态已被广泛研究,但是尚未完全了解尼罗罗非鱼（Oreochromisniloticus）不同组织中无机砷的生物积累和生物转化。本研究旨在研究As在尼罗罗非鱼中的生物富集，以及评估主要砷物种的分布(As(III)，如（V），MMA,DMA,和AsB）在肝脏中，胃,吉尔,和肌肉，在1天和7天期间以5.0和10.0mgL-1的浓度受控暴露于As（III）和As（V）之后。通过电感耦合等离子体质谱法(ICP-MS)测定总As。对于两种暴露(As(III)和As(V))，暴露7天后的总As水平在肝脏中最高，在肌肉中最低。总的来说,处理后，暴露于As（III）的尼罗罗非鱼显示出更高的组织As水平，与As(V)曝光相比。使用液相色谱与ICP-MS（LC-ICP-MS）联用的组织中存在的砷的形态，揭示了As的生物转化包括As(V)还原为As(III)，甲基化成单甲基arsonic酸（MMA）和二甲基arsinic酸（DMA），并随后转化为无毒的砷甜菜碱（AsB），这是主要的砷形式。最后,通过联合暴露于As（III）测试了硒在生物积累过程中的相互作用和拮抗作用，砷中毒性最大的物种,连同四价硒(Se(IV))。结果表明，罗非鱼的砷毒性降低了4-6倍。
