Xie Fangli, Lampi Mark A, Dixon D George, Greenberg Bruce M
Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Environ Toxicol Chem. 2007 Jul;26(7):1425-32. doi: 10.1897/06-224r.1.
Recently, we showed that reactive oxygen species (ROS) formation was involved in the toxicity of the redox-active metal Cu and mixtures of Cu plus a photomodified polycyclic aromatic hydrocarbon (PAH), phenanthrenequinone (PHQ), to Daphnia magna. It is unknown, however, if similar results can be observed for metals with lower or no redox activity and their mixtures with PHQ. In the present study using D. magna, the toxicity of Ni, a weakly redox-active metal, and of Cd, a non-redox active metal, was examined with or without PHQ. The abilities of Ni, Cd, PHQ, and binary mixtures of metal plus PHQ to generate ROS were measured using a 2',7'-dichlorofluorescein fluorescence assay. The results were compared with the results of Cu and mixtures of Cu plus PHQ from a recent study by our group. The order of metal toxicity to D. magna was found to be Cd > or = Cu > Ni. As with Cu/PHQ mixtures, synergistic toxicity was observed for mixtures of Ni and PHQ, whereas additive toxicity was observed for mixtures of Cd and PHQ. Alone, PHQ had no impact on ROS levels in D. magna. Nickel alone caused elevated ROS, which was further enhanced in the presence of PHQ. Neither Cd nor Cd/PHQ mixtures increased ROS production. Attenuation of toxicity and ROS production was observed in response to treatment with low concentrations of L-ascorbic acid. These results indicate potential toxic interactions between metals and modified PAHs. With redox-active metals, such as Cu and Ni, and modified PAHs, such as PHQ, these interactions can involve ROS formation.
最近，我们发现活性氧（ROS）的形成与氧化还原活性金属铜以及铜与光改性多环芳烃（PAH）菲醌（PHQ）的混合物对大型溞的毒性有关。然而，对于氧化还原活性较低或无氧化还原活性的金属及其与PHQ的混合物，是否能观察到类似结果尚不清楚。在本研究中，我们以大型溞为研究对象，考察了弱氧化还原活性金属镍和无氧化还原活性金属镉在单独存在或与PHQ共存时的毒性。使用2',7'-二氯荧光素荧光测定法测量了镍、镉、PHQ以及金属与PHQ的二元混合物产生ROS的能力。将结果与我们小组最近一项研究中铜及铜与PHQ混合物的结果进行了比较。发现金属对大型溞的毒性顺序为镉≥铜＞镍。与铜/PHQ混合物一样，镍和PHQ的混合物表现出协同毒性，而镉和PHQ的混合物表现出相加毒性。单独来看，PHQ对大型溞的ROS水平没有影响。单独的镍会导致ROS升高，在有PHQ存在时会进一步增强。镉及其与PHQ的混合物均未增加ROS的产生。用低浓度的L-抗坏血酸处理后，观察到毒性和ROS产生减弱。这些结果表明金属与改性PAHs之间存在潜在的毒性相互作用。对于氧化还原活性金属，如铜和镍，以及改性PAHs，如PHQ，这些相互作用可能涉及ROS的形成。
