Aharchaou Imad, Maul Armand, Pons Marie-Noëlle, Pauly Danièle, Poirot Hélène, Flayac Justine, Rodius François, Rousselle Philippe, Beuret Maximilien, Battaglia Eric, Vignati Davide A L
Université de Lorraine, CNRS, LIEC, F-57000, Metz, France.
Université de Lorraine, CNRS, LRGP, F-54000, Nancy, France.
Chemosphere. 2022 Jun;297:134090. doi: 10.1016/j.chemosphere.2022.134090. Epub 2022 Feb 23.
Chromium has two main oxidation states, Cr(III) and Cr(VI), that can occur simultaneously in natural waters. Current consensus holds that Cr(VI) is of high ecotoxicological concern, but regards Cr(III) as poorly bioavailable and relatively non-toxic. In this work, the effects and bioaccumulation of Cr(III), Cr(VI) and their mixture were studied using the freshwater clam Corbicula fluminea as a model organism. Mixture exposures were carried out using solutions isotopically enriched in Cr(III) or Cr(VI), allowing to quantify the contribution of each redox form to total Cr accumulation in the clams. Following exposure to individual redox forms, Cr(III) accumulated preferentially in the digestive glands and Cr(VI) in the gills of C. fluminea. In mixture exposures, both redox forms accumulated mainly in the gills; the concentration of Cr(III) in the digestive glands being much lowered compared with individual exposures. Both oxidation states affected the expression of biomarkers related to energy reserves, cellular damage and mitochondrial functioning, as well as the expression of mRNA for detoxification genes. The observed effects differed between gills and digestive glands. The present study suggests that Cr(III) is a bioavailable and biologically active elemental species deserving more consideration by the ecotoxicological community.
铬有两种主要氧化态，即Cr(III)和Cr(VI)，它们可同时存在于天然水体中。目前的共识是，Cr(VI)具有较高的生态毒理学风险，但认为Cr(III)的生物可利用性差且相对无毒。在这项研究中，以淡水蚬（Corbicula fluminea）作为模式生物，研究了Cr(III)、Cr(VI)及其混合物的影响和生物累积情况。使用富含Cr(III)或Cr(VI)的同位素溶液进行混合暴露实验，从而能够量化每种氧化还原形态对蚬中总铬累积的贡献。暴露于单一氧化还原形态后，Cr(III)优先在淡水蚬的消化腺中累积，而Cr(VI)则优先在鳃中累积。在混合暴露实验中，两种氧化还原形态主要在鳃中累积；与单一暴露相比，消化腺中Cr(III)的浓度大幅降低。两种氧化态均影响了与能量储备、细胞损伤和线粒体功能相关的生物标志物的表达，以及解毒基因的mRNA表达。鳃和消化腺中的观察结果有所不同。本研究表明，Cr(III)是一种具有生物可利用性和生物活性的元素形态，值得生态毒理学界给予更多关注。
