Zelinová Veronika, Mistrík Igor, Pavlovkin Ján, Tamás Ladislav
Institute of Botany, Slovak Academy of Sciences, Dúbravská cesta 9, 84523, Bratislava, Slovak Republic.
Protoplasma. 2013 Oct;250(5):1057-65. doi: 10.1007/s00709-013-0481-3. Epub 2013 Jan 17.
The purpose of this study was to analyse the alterations of glutathione peroxidase (GPX) expression and activity during the recovery period after a short-term treatment of barley root tip with cadmium (Cd) and hydrogen peroxide (H(2)O(2)). The transcript level of GPX increased as early as 1 h and GPX activity 3 h after short-term treatment independently of Cd concentration. In 15 μM Cd-treated roots, its expression reached a peak within 2 h and sustained until 3 h, after which it gradually declined. After 6 h of short-term Cd treatment, the activity of GPX was the highest in the 15-μM Cd-treated roots. At higher Cd concentrations, the activity of GPX was lower than in 15 μM Cd-treated roots, but still higher than in control roots. A considerable increase in H(2)O(2) production was observed even after only 1 h of short-term exposure of roots to 30 and 60 μM Cd, while after 15 μM Cd exposure, its production increased 3 h after the treatment. Lipid peroxidation increased even 1 h after short-term treatment in a Cd concentration-dependent manner. A considerable decrease of GPX activity was observed after the exposure of roots to H(2)O(2) or t-butyl hydroperoxide in a concentration-dependent manner despite that its expression increased even 1 h after short-term treatment. Presumable, under high acute Cd stress, rapid accumulation of H(2)O(2) leads to the disturbance of basal metabolic processes affecting also GPX activity. In contrast, high GPX activity under moderate Cd stress maintains cell function despite the high rate of H(2)O(2) metabolism in root tip.
本研究的目的是分析在短期用镉（Cd）和过氧化氢（H₂O₂）处理大麦根尖后的恢复期内，谷胱甘肽过氧化物酶（GPX）表达和活性的变化。短期处理后，无论Cd浓度如何，GPX的转录水平早在1小时就升高，GPX活性在3小时升高。在15 μM Cd处理的根中，其表达在2小时内达到峰值并持续到3小时，之后逐渐下降。短期Cd处理6小时后，15 μM Cd处理的根中GPX活性最高。在较高的Cd浓度下，GPX活性低于15 μM Cd处理的根，但仍高于对照根。即使根仅短期暴露于30和60 μM Cd 1小时后，也观察到H₂O₂产量显著增加，而在暴露于15 μM Cd后，其产量在处理后3小时增加。短期处理1小时后，脂质过氧化以Cd浓度依赖性方式增加。尽管短期处理1小时后其表达增加，但根暴露于H₂O₂或叔丁基过氧化氢后，观察到GPX活性以浓度依赖性方式显著降低。推测在高急性Cd胁迫下，H₂O₂的快速积累导致基础代谢过程紊乱，也影响GPX活性。相反，在中度Cd胁迫下，尽管根尖中H₂O₂代谢率高，但高GPX活性维持细胞功能。
