Department of Botany, School of Biology, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece.
Department of Botany, School of Biology, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece.
Ecotoxicol Environ Saf. 2021 Jan 15;208:111386. doi: 10.1016/j.ecoenv.2020.111386. Epub 2020 Oct 6.
The present work aims to provide insight into interactions between trace metals and higher plants, focusing on nickel uptake and its effects in seagrasses at environmentally relevant concentrations. Total and intracellular nickel accumulation kinetics, nickel effects on structural cell components, oxidative stress marker and cellular viability, and the accumulation kinetics-toxic effects relationship were investigated in leaves of Halophila stipulacea plants incubated in seawater under laboratory conditions containing nickel ions at 0.01-10 mg L for 14 days. Nickel accumulation kinetics in H. stipulacea young and older apical leaves followed a Michaelis-Menten-type equation, allowing the calculation of uptake parameters; uptake rate (V) and equilibrium concentration (C) tended to increase with the increase of nickel concentration in the medium. A dose- and uptake parameter-dependent actin filament (AF) and endoplasmic reticulum (ER) impairment was observed, whereas no effects occurred on microtubules and cell ultrastructure. AF disturbance and ER aggregation were firstly observed in differentiated cells at the lowest concentration on the 12th and 14th day, respectively, while AF disruption in meristematic cells firstly occurred at 0.05 mg L; the effects appeared earlier and were more acute at higher concentrations. Increased HO levels were detected, while, at the highest exposures, a significant reduction in epidermal cell viability in older leaves occurred. The lowest total nickel concentrations in young leaves associated with AF disturbance onset at nickel exposure concentrations of 0.01-1 mg L varied between 18.98 and 63.93 μg g dry wt; importantly, they were comparable to nickel concentrations detected in seagrass leaves from various locations. The relationships between exposure concentration, uptake kinetic parameters and toxic effect onset were satisfactorily described by regression models. Our findings suggest that (a) nickel may pose a threat to seagrass meadows, (b) H. stipulacea can be regarded as an efficient biomonitor of nickel, (c) AF and ER impairment in seagrass leaves can be considered as early biomarkers of nickel-induced stress, and (d) the regression models obtained can be used as a tool to evaluate ambient nickel levels and to detect ecotoxicologically significant nickel contamination. The data presented can be utilized in the management and conservation of the coastal environment.
本研究旨在深入探讨痕量金属与高等植物之间的相互作用，重点研究镍在环境相关浓度下在海草中的吸收及其影响。在实验室条件下，用含镍离子的海水培养 14 天，研究了镍 0.01-10mg/L 对茎枝伸长区顶端幼叶和老叶中镍总积累动力学、细胞内镍积累动力学、镍对结构细胞成分的影响、氧化应激标志物和细胞活力的影响以及积累动力学-毒性效应关系。H. stipulacea 幼叶和老叶的镍积累动力学符合米氏方程，允许计算吸收参数；随着介质中镍浓度的增加，吸收速率（V）和平衡浓度（C）趋于增加。观察到剂量和吸收参数依赖性的肌动蛋白丝（AF）和内质网（ER）损伤，但微管和细胞超微结构不受影响。在第 12 天和第 14 天，分别在最低浓度的分化细胞中首次观察到 AF 紊乱和 ER 聚集，而在分裂细胞中，首先在 0.05mg/L 时出现 AF 破坏；在较高浓度下，这些影响出现得更早且更严重。HO 水平升高，而在最高暴露下，老叶表皮细胞活力显著降低。在镍暴露浓度为 0.01-1mg/L 时，幼叶中与 AF 紊乱起始相关的总镍浓度最低值为 18.98-63.93μg/g 干重，这一数值与从不同地点采集的海草叶片中检测到的镍浓度相当。暴露浓度、吸收动力学参数和毒性效应起始之间的关系可以通过回归模型得到很好的描述。我们的研究结果表明：（a）镍可能对海草草甸构成威胁；（b）H. stipulacea 可以作为镍的有效生物监测物；（c）海草叶片中的 AF 和 ER 损伤可以作为镍诱导应激的早期生物标志物；（d）获得的回归模型可用作评估环境镍水平和检测生态毒理学上有意义的镍污染的工具。本研究结果可用于沿海环境的管理和保护。
