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Induction of Oxidative Stress and Antioxidative Mechanisms in Arabidopsis thaliana after Uranium Exposure at pH 7.5.

Saenen E, Horemans N, Vanhoudt N, Vandenhove H, Biermans G, Van Hees M, Wannijn J, Vangronsveld J, Cuypers A - Int J Mol Sci (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium. eline.saenen@sckcen.be.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus

Enzyme capacities (units (U)·g−1 FW) of ascorbate peroxidase (A, APX) and glutathione reductase (B, GR) in Arabidopsis thaliana roots exposed to different U concentrations for three days at pH 7.5. Values represent the mean ± S.E. of at least four biological replicates. Data points with different letters are significantly different (p < 0.05).
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ijms-16-12405-f004: Enzyme capacities (units (U)·g−1 FW) of ascorbate peroxidase (A, APX) and glutathione reductase (B, GR) in Arabidopsis thaliana roots exposed to different U concentrations for three days at pH 7.5. Values represent the mean ± S.E. of at least four biological replicates. Data points with different letters are significantly different (p < 0.05).

Mentions: Capacities of several enzymes related to the antioxidative defence system were analysed at protein level to investigate their importance under U stress (Figure 4 and Figure 5). In the roots, a significant increase in ascorbate peroxidase (APX) capacity was observed after exposure to 25 µM U or higher as compared to the control plants (Figure 4A). An increasing trend in the capacity of glutathione reductase (GR) was also observed after U exposure, with a significant increase after exposure to 100 µM U (Figure 4B). No significant differences were observed in the capacities of CAT, guaiacol peroxidase (GPX), syringaldazine peroxidase (SPX) and SOD (Table S1).


Induction of Oxidative Stress and Antioxidative Mechanisms in Arabidopsis thaliana after Uranium Exposure at pH 7.5.

Saenen E, Horemans N, Vanhoudt N, Vandenhove H, Biermans G, Van Hees M, Wannijn J, Vangronsveld J, Cuypers A - Int J Mol Sci (2015)

Enzyme capacities (units (U)·g−1 FW) of ascorbate peroxidase (A, APX) and glutathione reductase (B, GR) in Arabidopsis thaliana roots exposed to different U concentrations for three days at pH 7.5. Values represent the mean ± S.E. of at least four biological replicates. Data points with different letters are significantly different (p < 0.05).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490451&req=5

ijms-16-12405-f004: Enzyme capacities (units (U)·g−1 FW) of ascorbate peroxidase (A, APX) and glutathione reductase (B, GR) in Arabidopsis thaliana roots exposed to different U concentrations for three days at pH 7.5. Values represent the mean ± S.E. of at least four biological replicates. Data points with different letters are significantly different (p < 0.05).
Mentions: Capacities of several enzymes related to the antioxidative defence system were analysed at protein level to investigate their importance under U stress (Figure 4 and Figure 5). In the roots, a significant increase in ascorbate peroxidase (APX) capacity was observed after exposure to 25 µM U or higher as compared to the control plants (Figure 4A). An increasing trend in the capacity of glutathione reductase (GR) was also observed after U exposure, with a significant increase after exposure to 100 µM U (Figure 4B). No significant differences were observed in the capacities of CAT, guaiacol peroxidase (GPX), syringaldazine peroxidase (SPX) and SOD (Table S1).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Belgian Nuclear Research Centre (SCK•CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium. eline.saenen@sckcen.be.

ABSTRACT
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.

No MeSH data available.


Related in: MedlinePlus