Cadmium toxicity investigated at the physiological and biophysical levels under environmentally relevant conditions using the aquatic model plant Ceratophyllum demersum
Cadmium toxicity investigated at the physiological and biophysical levels under environmentally relevant conditions using the aquatic model plant Ceratophyllum demersum
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DOI：
10.1111/nph.13840
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发表时间：
2016-06-01
期刊：
影响因子：
9.4
通讯作者：
Kuepper, Hendrik
中科院分区：
文献类型：
--
作者：
Andresen, Elisa;Kappel, Sophie;Kuepper, Hendrik
镉（Cd）是一种重要的环境污染物，对大多数生物体有毒。我们的目的是揭示模型水生植物金鱼藻暴露于自然界中低浓度（nM）镉的情况下镉的毒性机制。实验是在环境相关条件下进行的，包括类似自然的光和温度循环以及低生物量与水的比率。我们测量了叶绿素 (Chl) 荧光动力学、氧交换、活性氧和色素的浓度、金属与蛋白质的结合以及淀粉和金属的积累。大多数参数的抑制阈浓度为 20 nM。低于这个浓度，几乎观察不到任何应激症状。第一个抑制位点是光合光反应（光系统 II (PSII) 反应中心的最大量子产率测量为 F-v/F-m、光适应的 PSII 活性 Phi(PSII) 和总叶绿素）。 PSII 光捕获复合物 (LHCII) 的三聚体比 LHC 单体减少更多，单体中 Cd 的检测表明 Chl 分子中镁 (Mg) 被 Cd 取代。由于光合作用和能量耗散功能失调，出现了活性氧（超氧化物和过氧化氢）。镉在比之前报道的浓度低得多的浓度下对大型植物产生负面影响，强调了应用环境相关条件进行研究的重要性。可以建立一系列抑制事件。
Cadmium (Cd) is an important environmental pollutant and is poisonous to most organisms. We aimed to unravel the mechanisms of Cd toxicity in the model water plant Ceratophyllum demersum exposed to low (nM) concentrations of Cd as are present in nature.Experiments were conducted under environmentally relevant conditions, including nature-like light and temperature cycles, and a low biomass to water ratio. We measured chlorophyll (Chl) fluorescence kinetics, oxygen exchange, the concentrations of reactive oxygen species and pigments, metal binding to proteins, and the accumulation of starch and metals.The inhibition threshold concentration for most parameters was 20 nM. Below this concentration, hardly any stress symptoms were observed. The first site of inhibition was photosynthetic light reactions (the maximal quantum yield of photosystem II (PSII) reaction centre measured as F-v/F-m, light-acclimated PSII activity Phi(PSII), and total Chl). Trimers of the PSII light-harvesting complexes (LHCIIs) decreased more than LHC monomers and detection of Cd in the monomers suggested replacement of magnesium (Mg) by Cd in the Chl molecules. As a consequence of dysfunctional photosynthesis and energy dissipation, reactive oxygen species (superoxide and hydrogen peroxide) appeared.Cadmium had negative effects on macrophytes at much lower concentrations than reported previously, emphasizing the importance of studies applying environmentally relevant conditions. A chain of inhibition events could be established.