Saenen Eline, Horemans Nele, Vanhoudt Nathalie, Vandenhove Hildegarde, Biermans Geert, Van Hees May, Wannijn Jean, Vangronsveld Jaco, Cuypers Ann
Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium.
Int J Mol Sci. 2015 Jun 2;16(6):12405-23. doi: 10.3390/ijms160612405.
To evaluate the environmental impact of uranium (U) contamination, it is important to investigate the effects of U at ecologically relevant conditions. Since U speciation, and hence its toxicity, strongly depends on environmental pH, the present study aimed to investigate dose-dependent effects of U at pH 7.5. Arabidopsis thaliana plants (Mouse-ear Cress) were exposed for three days to different U concentrations at pH 7.5. In the roots, the increased capacities of ascorbate peroxidase and glutathione reductase indicate an important role for the ascorbate-glutathione cycle during U-induced stress. However, a significant decrease in the ascorbate redox state was observed after exposure to 75 and 100 µM U, indicating that those roots are severely stressed. In accordance with the roots, the ascorbate-glutathione cycle plays an important role in the antioxidative defence systems in A. thaliana leaves exposed to U at pH 7.5 as the ascorbate and glutathione biosynthesis were upregulated. In addition, small inductions of enzymes of the antioxidative defence system were observed at lower U concentrations to counteract the U-induced stress. However, at higher U concentrations it seems that the antioxidative defence system of the leaves collapses as reductions in enzyme activities and gene expression levels were observed.
为评估铀（U）污染对环境的影响，在生态相关条件下研究铀的影响至关重要。由于铀的形态及其毒性很大程度上取决于环境pH值，本研究旨在探究pH值为7.5时铀的剂量依赖性效应。将拟南芥植株（鼠耳芥）在pH值为7.5的条件下暴露于不同铀浓度中三天。在根部，抗坏血酸过氧化物酶和谷胱甘肽还原酶活性增加，表明抗坏血酸-谷胱甘肽循环在铀诱导的胁迫过程中发挥重要作用。然而，暴露于75和100μM铀后，抗坏血酸氧化还原状态显著下降，表明这些根部受到严重胁迫。与根部情况一致，在pH值为7.5的条件下，暴露于铀的拟南芥叶片中，抗坏血酸-谷胱甘肽循环在抗氧化防御系统中起重要作用，因为抗坏血酸和谷胱甘肽的生物合成上调。此外，在较低铀浓度下观察到抗氧化防御系统的酶有小幅度诱导，以对抗铀诱导的胁迫。然而，在较高铀浓度下，叶片的抗氧化防御系统似乎崩溃，因为观察到酶活性和基因表达水平下降。
