Physiological, structural and ultrastructural impacts of silver nanoparticles on the seagrass Cymodocea nodosa. (June 2020)

• Record Type: Journal Article
• Authors: Mylona, Zoi; Panteris, Emmanuel; Moustakas, Michael; Kevrekidis, Theodoros; Malea, Paraskevi
• Is Part Of: Chemosphere. Volume 248(2020)
• Publication Date: 2020-06
• Subjects: Marine plant -- Toxicity -- Cellular effect -- Physiological response -- Biomarker -- Risk assessment; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.126066
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: 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 −1 ) under laboratory conditions for 8 days were examined. An increase in H2 O2 level, indicating oxidative stress, occurred after the 4th day even at 0.0002 mg L −1 . Increased antioxidant enzyme activity, potentially contributing to H2 O2 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 −1 ; microtubule, endoplasmic reticulum, chloroplast and mitochondrion disturbance appeared after 8 days at 0.02 mg L −1, while toxic effects were generally more acute at 0.2 mg L −1 . 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 (H2 O2 ) 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. Highlights: AgNPs at environmentally relevant concentrations cause toxic effects on seagrasses. AgNPs induce oxidative stress in Cymodocea nodosa at low concentrations (0.2 μg L −1 ). AgNPs impair cytoskeleton, endoplasmic reticulum, cell ultrastructure, leaf growth. H2 O2 level and actin filament damage are early warning indicators of AgNP stress. AgNPs may pose a significant potential risk to the coastal environment.