Kováčik Jozef, Babula Petr, Hedbavny Josef, Kryštofová Olga, Provaznik Ivo
Institute of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic.
Department of Natural Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Palackého 1/3, 612 42 Brno, Czech Republic.
Chemosphere. 2015 Feb;120:23-30. doi: 10.1016/j.chemosphere.2014.05.074. Epub 2014 Jun 24.
Physiological responses of Scenedesmus quadricauda to Cr(VI) and Cr(III) excess were studied in buffer with circumneutral pH (6.5). Total Cr content was similar in low (1 μM of both oxidation states) but higher in 10 μM Cr(VI) treatment and high accumulation potential was detected (80-82% and 41-65% in 1 and 10 μM treatments, respectively). Specific fluorescence indicator (6-((anthracen-9-yl) methyleneamino)-2H-chromen-2-one) confirmed partial reduction of Cr(VI) to Cr(III) under exposure conditions. Viability and chlorophyll autofluorescence were more depleted by Cr(VI) while Cr(III) stimulated increase in ROS and lipid peroxidation. Antioxidative enzyme activities showed significantly higher values in 10 μM treatments of both Cr oxidation states. Depletion of mitochondrial proteins was not reflected in alteration of total soluble proteins indicating sensitivity of this organelle to Cr and TTC test showed no clear oxidation state-related effect. In this view, "Cr(VI) is not more toxic than Cr(III)" at least for some parameters. Subsequent study with the application of 10 μM Cr(VI) confirmed that HEPES buffer is more suitable exposure solution for toxicological studied than water or inorganic salts (higher chlorophyll autofluorescence was observed) and pH 6.5 is more suitable than low or high pH (4.5 or 8.5) in terms of Cr uptake. Another known Cr(III) fluorescence indicator (naphthalimide-rhodamine) also confirmed partial reduction of Cr(VI) to Cr(III) at acidic pH but only traces were seen at alkaline pH.
在pH值为中性（6.5）的缓冲液中研究了四尾栅藻对过量六价铬和三价铬的生理响应。在低浓度（两种氧化态均为1 μM）下，总铬含量相似，但在10 μM六价铬处理中更高，并且检测到高积累潜力（在1 μM和10 μM处理中分别为80 - 82%和41 - 65%）。特异性荧光指示剂（6 - （（蒽 - 9 - 基）亚甲基氨基） - 2H - 色烯 - 2 - 酮）证实了在暴露条件下六价铬部分还原为三价铬。六价铬对活力和叶绿素自发荧光的消耗更大，而三价铬刺激了活性氧和脂质过氧化的增加。抗氧化酶活性在两种铬氧化态的10 μM处理中均显示出显著更高的值。线粒体蛋白的消耗并未反映在总可溶性蛋白的变化中，表明该细胞器对铬敏感，并且氯化三苯基四氮唑试验未显示出与氧化态相关的明显影响。从这个角度来看，至少对于某些参数，“六价铬并不比三价铬毒性更大”。随后使用10 μM六价铬的研究证实，对于毒理学研究而言，HEPES缓冲液比水或无机盐更适合作为暴露溶液（观察到更高的叶绿素自发荧光），并且就铬吸收而言，pH 6.5比低pH或高pH（4.5或8.5）更合适。另一种已知的三价铬荧光指示剂（萘二甲酰亚胺 - 罗丹明）也证实在酸性pH下六价铬部分还原为三价铬，但在碱性pH下仅观察到痕量。
