The potential toxicity of copper nanoparticles and copper sulphate on juvenile Epinephelus coioides

Response of plasma copper, ceruloplasmin, iron and ions in carp, Cyprinus carpio to waterborne copper ion and nanoparticle exposure

In this study, Cyprinus carpio was exposed to 0.25mgL(-1) copper as either copper sulfate (CuSO4) or copper oxide nanoparticles (nano-Cu), and 25mgL(-1) copper as nano-Cu for 14days. CuSO4 and high concentration of nano-Cu led to a significant increase in plasma total copper levels. Plasma free copper levels increased significantly in all copper-exposed treatments. Except for low concentration of nano-Cu after 7 and 14days, copper exposure generally led to a significant decrease in plasma ceruloplasmin levels. Plasma iron levels increased significantly in CuSO4 (all times) and nano-Cu (7th and 14th days) treatments. A significant elevation in plasma total iron binding capacity (TIBC) was observed after 3days in the fish exposed to low concentration nano-Cu, and after 14days in all copper-exposed treatments. Transferrin saturation (TSA) ratio showed significant increase in CuSO4 (3rd and 7th days) and the high concentration nano-Cu (7th day) treatments. Decrease in plasma chloride (7th and 14th days) and sodium (14th days) was observed in CuSO4 treatment. In conclusion, the results suggest that ionic copper is mainly absorbed via fish gill, whereas, nano-copper are more likely absorbed via gut. Also, data suggest that ionic copper has more adverse effects on the examined plasma biochemical characteristics compared to the equivalent nano-copper concentration, which may be due to the lower copper absorption by fish in the nano-copper suspension.

A comparative analysis on the in vivo toxicity of copper nanoparticles in three species of freshwater fish

Copper nanoparticles (CuNPs) are used extensively in a wide range of products and the potential for toxicological impacts in the aquatic environment is of high concern. In this study, the fate and the acute toxicity of spherical 50nm copper nanoparticles was assessed in juvenile rainbow trout (Oncorhynchus mykiss), fathead minnow (Pimephales promelas) and zebrafish (Danio rerio) for in vivo aqueous exposures following standardized OECD 203 guideline tests. The fate of the CuNPs in the aqueous media was temperature dependent. At the higher study temperature (26±1°C), there was both an enhanced particle aggregation and higher rate of dissolution compared with that at the lower study temperature (15±1°C). 96h LC50s of the CuNPs were 0.68±0.15, 0.28±0.04 and 0.22±0.08mg Cu/L for rainbow trout, fathead minnow and zebrafish, respectively. The 96h lowest-observed-effect concentration (LOEC) for the CuNPs were 0.17, 0.023 and <0.023mg/L for rainbow trout, fathead minnow, and zebrafish respectively, and are below the predicted environmental concentration of CuNPs for some aquatic environments suggesting a possible ecotoxicological risk to fish. Soluble copper was one of main drivers for the acute toxicity of the copper nanoparticles suspensions. Both CuNPs suspension and copper nitrate caused damage to gill filaments and gill pavement cells, with differences in sensitivity for these effects between the fish species studied. We show therefore common toxicological effects of CuNPs in different fish species but with differences in sensitivity with implications for hazard extrapolation between fish species.

A Comparison Effect of Copper Nanoparticles versus Copper Sulphate on Juvenile Epinephelus coioides: Growth Parameters, Digestive Enzymes, Body Composition, and Histology as Biomarkers

Copper nanoparticles (Cu-NPs) are components in numerous commercial products, but little is known about their potential hazard in the marine environments. In this study the effects of Cu-NPs and soluble Cu on juvenile Epinephelus coioides were investigated. The fish were exposed in triplicate to control, 20 or 100 µg Cu L(-1) as either copper sulphate (CuSO4) or Cu-NPs for 25 days. The growth performance decreased with increasing CuSO4 or Cu-NPs dose, more so in the CuSO4 than Cu-NPs treatment. Both forms of Cu exposure inhibited activities of digestive enzymes (protease, amylase, and lipase) found in liver, stomach, and intestine. With an increase in CuSO4 and Cu-NPs dose, crude protein and crude lipid decreased, but ash and moisture increased, more so in the CuSO4 than Cu-NPs treatment. The Cu-NPs treatment caused pathologies in liver and gills, and the kinds of pathologies were broadly of the same type as with CuSO4. With an increase in CuSO4 or Cu-NPs dose, the total polyunsaturated fatty acids decreased, but total monounsaturated fatty acids and total saturated fatty acids increased compared to control. Overall, these data showed that Cu-NPs had a similar type of toxic effects as CuSO4, but soluble Cu was more toxic than Cu-NPs.

Multiwall Carbon Nanotube-Induced Apoptosis and Antioxidant Gene Expression in the Gills, Liver, and Intestine of Oryzias latipes

Multiwall carbon nanotubes (MWCNTs) have many attractive properties with potential applications in various fields. Despite their usefulness, however, the associated waste can be hazardous to the environment. To examine adverse effects in aquatic environments, Oryzias latipes were exposed to MWCNTs dispersed in water for 14 days and apoptosis and antioxidant gene expression were observed. This work showed that in gills exposed to 100 mg/L MWCNTs for 4 days, there was significant p53, caspase-3 (Cas3), caspase-8 (Cas8), and caspase-9 (Cas9) gene expression relative to the controls, while catalase (CAT) and glutathione-S-transferase (GST) expression were reduced. At 14 days, CAT, GST, and metallothionein (MT) were induced significantly in the gills and Cas3, Cas8, and Cas9 were induced in the liver. No significant gene induction was seen in intestine. Intracellular reactive oxygen species (ROS) were increased significantly only at 14 days. Histologically, no apoptosis was observed with exposure to 100 mg/L MWCNTs for 21 days. The gills were more sensitive to MWCNT toxicity than the other organs. Males had higher apoptosis gene induction than females. These results demonstrated that MWCNTs could cause apoptosis in a manner influenced by tissue and gender in aqueous environments.

Effect of copper nanoparticles and copper sulphate on oxidation stress, cell apoptosis and immune responses in the intestines of juvenile Epinephelus coioides

Copper nanoparticles (Cu-NPs) are widely used in various industrial and commercial applications, but little is known about their potential hazard in the intestines of marine teleosts. In this study we investigated the effects of Cu-NPs and soluble Cu in the intestines of juvenile Epinephelus coioides. The fish were exposed in triplicate to control, 20 or 100 μg Cu L(-1) as either copper sulphate (CuSO₄) or Cu-NPs for 25 days. With an increase in Cu-NPs or CuSO₄ dose, the concentration of malonaldehyde in the intestines significantly increased, whereas the activities of total superoxide dismutase and catalase as well as glutathione concentration decreased compared to the control. Statistical analysis of an apoptosis index of intestinal cells showed that general dose-dependent apoptosis was induced by Cu-NPs or CuSO₄, with Cu-NPs inducing the significantly higher apoptosis index than CuSOv. Caspase-3 and caspase-9 activities were increased with an increase in Cu-NPs or CuSO₄ dose, more so in the Cu-NPs than CuSO₄ treatment. With an increase in Cu-NPs or CuSOv dose, succinate dehydrogenase and Na(+)-K(+)-ATPase activity and cytochrome c concentration in mitochondria decreased, accompanied by increased cytochrome c concentration in the cytosol. Concentration of heat shock proteins 70 and 90 in the intestines and expression of corresponding genes were enhanced with an increase in the Cu-NPs or CuSOv dose, but the concentrations and expressions of immunoglobulin M and lysozyme decreased (more in the Cu-NPs than CuSO₄ treatment) compared to the control. Expression of interleukin-1beta and tumor necrosis factor-alpha showed a dose-dependent increase with the increased Cu-NPs or CuSO₄ dose, with the highest expression found in the Cu-NPs treatment. In conclusion, Cu-NPs had similar toxic effects as CuSOv in the intestines of juvenile E. coioides, but toxicity of Cu-NPs was more severe than that of CuSO₄.

Evaluation of single and joint toxicity of perfluorooctane sulfonate, perfluorooctanoic acid, and copper to Carassius auratus using oxidative stress biomarkers

Perfluorooctane sulfonate, perfluorooctanoic acid, and copper have been recently regarded as ubiquitous environmental contaminants in aquatic ecosystems worldwide. However, data on their possible combined toxic effects on aquatic organisms are still lacking. In this study, a systematic experimental approach was used to assess the impacts of these chemicals and their mixtures on hepatic antioxidant status of Carassius auratus after 4 days. Oxidative stress was apparently observed for joint exposure by determining biochemical parameters (superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and malondialdehyde). The integrated biomarker response index was calculated to rank the toxicity order, from which the synergistic effect was tentatively proposed for joint-toxicity action. In addition, these treatments significantly altered trace element homeostasis in different fish tissues, and the concentration distribution of these test chemicals was also measured. Taken together, these results provided some valuable toxicological data on the joint effects of perfluorinated compounds and heavy metals on aquatic species, which can facilitate further understanding on the potential risks of other coexisting pollutants in the natural aquatic environment.

Comparative effects of dissolved copper and copper oxide nanoparticle exposure to the sea anemone, Exaiptasia pallida

Increasing use of metal oxide nanoparticles (NP) by various industries has resulted in substantial output of these NP into aquatic systems. At elevated concentrations, NP may interact with and potentially affect aquatic organisms. Environmental implications of increased NP use are largely unknown, particularly in marine systems. This research investigated and compared the effects of copper oxide (CuO) NP and dissolved copper, as copper chloride (CuCl2), on the sea anemone, Exaiptasia pallida. Sea anemones were collected over 21 days and tissue copper accumulation and activities of the enzymes: catalase, glutathione peroxidase, glutathione reductase, and carbonic anhydrase were quantified. The size and shape of CuO NP were observed using a ecanning electron microscope (SEM) and the presence of copper was confirmed by using Oxford energy dispersive spectroscopy systems (EDS/EDX). E. pallida accumulated copper in their tissues in a concentration- and time-dependent manner, with the animals exposed to CuCl2 accumulating higher tissue copper burdens than those exposed to CuO NP. As a consequence of increased copper exposure, as CuO NP or CuCl2, anemones increased activities of all of the antioxidant enzymes measured to some degree, and decreased the activity of carbonic anhydrase. Anemones exposed to CuO NP generally had higher anti-oxidant enzyme activities than those exposed to the same concentrations of CuCl2. This study is useful in discerning differences between CuO NP and dissolved copper exposure and the findings have implications for exposure of aquatic organisms to NP in the environment.

Copper exposure induces toxicity to the antioxidant system via the destruction of Nrf2/ARE signaling and caspase-3-regulated DNA damage in fish muscle: amelioration by myo-inositol

The muscle is the main portion of fish that is consumed by humans. Copper (Cu) can induce oxidative damage in fish muscle. However, the effects of Cu exposure on the muscle antioxidant system and molecular patterns and preventive measures against these effects remain unclear. In this study, ROS production, enzymatic and mRNA levels of antioxidant enzymes and NF-E2-related factor 2 (Nrf2) signaling-related molecules, antioxidant response element (ARE) binding ability, DNA fragmentation and caspase-3 activities were analyzed in fish muscle following Cu exposure or myo-inositol (MI) pre-administration. The results indicated that contamination due to copper exposure caused an approximately three-fold increase in ROS production, induced lipid peroxidation and protein oxidation, and resulted in depletion of the glutathione (GSH) content of fish muscle. Moreover, Cu exposure caused decreases in the activities of total superoxide dismutase (T-SOD), CuZnSOD, and glutathione peroxidase (GPx) that were accompanied by decreases in CuZnSOD, GPx1a, GPx1b and signaling factor protein kinase C delta mRNA levels. The decreases in the antioxidant enzyme gene mRNA levels were confirmed to be partly due to the reduced nuclear Nrf2 protein levels, poor ARE binding ability and increased caspase-3 signaling-modulated DNA fragmentation in the fish muscle. Interestingly, MI pre-treatment prevented fish muscle from Cu-induced oxidative damages mainly through increasing the GSH content, and increasing the CuZnSOD and GPx activities and corresponding mRNA levels and ARE binding ability. Taken together, our results show for the first time that Cu exposure caused oxidative damage to the muscle by decreasing the antioxidant enzyme activities via the down-regulation of the expression of genes related to the disruption of the Nrf2/ARE signaling, and this down-regulation was partially caused by caspase-3-regulated DNA fragmentation. Finally, MI protects fish against Cu toxicity.