Department of Botany, School of Biology, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece.
Laboratory of Environmental Research and Education, Democritus University of Thrace, Nea Hili, GR-68100, Alexandroupolis, Greece.
Chemosphere. 2020 Jun;248:126066. doi: 10.1016/j.chemosphere.2020.126066. Epub 2020 Feb 1.
Silver nanoparticles (AgNPs) are an emerging contaminant, currently considered to be a significant potential risk to the coastal environment. To further test potential risk, and to determine effect concentrations and sensitive response parameters, toxic effects of environmentally relevant AgNP concentrations on the seagrass Cymodocea nodosa were evaluated. Alterations of the cytoskeleton, endoplasmic reticulum, ultrastructure, photosystem II function, oxidative stress markers, cell viability, and leaf, rhizome and root elongation in C. nodosa exposed to AgNP concentrations (0.0002-0.2 mg L) under laboratory conditions for 8 days were examined. An increase in HO level, indicating oxidative stress, occurred after the 4th day even at 0.0002 mg L. Increased antioxidant enzyme activity, potentially contributing to HO level decline at the end of the experiment, and reduced protein content were also observed. Actin filaments started to diminish on the 6th day at 0.02 mg L; microtubule, endoplasmic reticulum, chloroplast and mitochondrion disturbance appeared after 8 days at 0.02 mg L, while toxic effects were generally more acute at 0.2 mg L. A dose-dependent leaf elongation inhibition was also observed; as for juvenile leaves, toxicity index increased from 2.8 to 40.7% with concentration. Hydrogen peroxide (HO) overproduction and actin filament disruption appeared to be the most sensitive response parameters, and thus could be utilized as early warning indicators of risk to seagrass meadows. A risk quotient of 1.33 was calculated, confirming previous findings, that AgNPs may pose a significant risk to the coastal environment.
银纳米粒子（AgNPs）是一种新兴的污染物，目前被认为是对沿海环境的重大潜在风险。为了进一步测试潜在风险，并确定效应浓度和敏感响应参数，评估了环境相关 AgNP 浓度对海草草 Cymodocea nodosa 的毒性影响。在实验室条件下，将 C. nodosa 暴露于 AgNP 浓度（0.0002-0.2 mg L）下 8 天，研究了细胞骨架、内质网、超微结构、光系统 II 功能、氧化应激标志物、细胞活力以及叶片、根茎和根伸长的变化。在第 4 天，即使在 0.0002 mg L 时，HO 水平的升高表明发生了氧化应激。抗氧化酶活性的增加，可能有助于实验结束时 HO 水平的下降，以及蛋白质含量的降低也观察到。在 0.02 mg L 时，第 6 天开始减少肌动蛋白丝；在 0.02 mg L 时，第 8 天出现微管、内质网、叶绿体和线粒体紊乱，而在 0.2 mg L 时，毒性作用通常更为急性。还观察到剂量依赖性的叶片伸长抑制；对于幼叶，毒性指数从 2.8%增加到 40.7%，浓度增加。过氧化氢（HO）的过度产生和肌动蛋白丝的破坏似乎是最敏感的响应参数，因此可以用作海草草甸风险的预警指标。计算出的风险商数为 1.33，证实了先前的发现，即 AgNPs 可能对沿海环境构成重大风险。
