Kabała Katarzyna, Janicka-Russak Małgorzata, Burzyński Marek, Kłobus Grazyna
Department of Plant Physiology, Institute of Plant Biology, University of Wrocław, Kanonia 6/8, 50-328 Wrocław, Poland.
J Plant Physiol. 2008;165(3):278-88. doi: 10.1016/j.jplph.2007.03.007. Epub 2007 Jul 20.
The effects of 10 microM cadmium, copper and nickel on the activities of vacuolar membrane and plasma membrane (PM) ATP-dependent proton pumps was investigated in Cucumis sativus L. root cells. It was demonstrated that vacuolar H+-ATPase (EC 3.6.3.14) and PM H+-ATPase (EC 3.6.3.6) differed in sensitivity to heavy metals. Exposure of cucumber seedlings to Cd, Cu and Ni had no significant effect on the activity of the vacuolar proton pump and, in the case of Ni, also on the activity of the PM proton pump. In contrast, Cd and Cu ions diminished both ATP hydrolysis and proton transport in plasma membranes. Transcript levels of genes encoding PM enzyme as well as the subunit A of tonoplast enzyme in roots stressed with heavy metals were similar to the control. Cd, Cu and Ni were accumulated in cucumber roots with similar efficiency, but their relative distribution between the symplast and apoplast differed. To explain the mechanism of heavy metal action on the plasma membranes of cucumber roots, the MDA content, as a lipid peroxidation product, and fatty acid composition were analyzed. It was shown that exposure of plants to Cd, Cu and Ni did not enhance the lipid peroxidation in the PM fraction. However, all metals caused an increase in the saturation of PM fatty acids and a decrease in the length of the fatty acid chain.
研究了10微摩尔镉、铜和镍对黄瓜（Cucumis sativus L.）根细胞液泡膜和质膜（PM）ATP依赖性质子泵活性的影响。结果表明，液泡H⁺-ATP酶（EC 3.6.3.14）和质膜H⁺-ATP酶（EC 3.6.3.6）对重金属的敏感性不同。黄瓜幼苗暴露于镉、铜和镍对液泡质子泵的活性没有显著影响，而对于镍，对质膜质子泵的活性也没有显著影响。相比之下，镉和铜离子减少了质膜中的ATP水解和质子运输。重金属胁迫下黄瓜根中编码质膜酶以及液泡膜酶亚基A的基因转录水平与对照相似。镉、铜和镍在黄瓜根中的积累效率相似，但它们在共质体和质外体之间的相对分布不同。为了解释重金属对黄瓜根质膜作用的机制，分析了脂质过氧化产物丙二醛（MDA）含量和脂肪酸组成。结果表明，植物暴露于镉、铜和镍不会增强质膜部分的脂质过氧化。然而，所有金属都导致质膜脂肪酸饱和度增加，脂肪酸链长度缩短。
