Changes in energy reserves and responses of some biomarkers in freshwater mussels exposed to metal-oxide nanoparticles.

In this study, responses of various biomarkers in the digestive gland and foot muscle of freshwater mussels (Unio tigridis) were investigated following exposure to Al2O3, CuO and TiO2 nanoparticles (NPs) for 14 days at different concentrations (0, 1, 3 and 9 mg NP/L). Mussels were fed on unicellular algae (Chlorella vulgaris) cultured in the laboratory. NP exposures caused significant increases (p < 0.05) in the levels of total glutathione (GSH), reduced-glutathione (rGSH), oxidized-glutathione (GSSG) and malondialdehyde (MDA) in the digestive gland. Oppositely, there were significant (p < 0.05) decreases in acetylcholinesterase activity in the foot muscles. Total energy reserves of the digestive gland and foot muscle significantly (p < 0.05) decreased, but only at the highest NP exposures. Nevertheless, NP exposures did not alter (p > 0.05) the algae filtering capacity of mussels. This study demonstrated that the biomarkers belonging to different metabolic systems responded to NP exposures, suggesting their usage in the monitoring studies for freshwater systems.

Accumulation and Distribution of Nanoparticles (Al2O3, CuO, and TiO2) in Tissues of Freshwater Mussel (Unio tigridis).

Freshwater mussels are used as an effective bioindicator of metal pollution. There is no data on the accumulation of any metal-oxide nanoparticles (NPs) in tissues of Unio tigridis. Thus, this study was undertaken to investigate accumulation of Al2O3, CuO, and TiO2 NPs following exposure to different concentrations (0, 1, 3, and 9 mg/L) of NPs for 14 days. Metal concentrations in tissues were determined by ICP-MS, while NP presence was demonstrated by transmission electron microscope (TEM) images. During the experiments, mussels were fed with cultured algae (Chlorella vulgaris). TEM images demonstrated the presence of NPs in digestive gland and muscle. TEM images also suggested that NPs were taken via the lysosomes or endosomes. Highest mean concentrations (µg/g d.w.) of aluminium (76.51), copper (111.63) and titanium (113.83) occurred in the gills and followed by the digestive glands and muscles. Algae consumption of mussels did not significantly differ among controls and NP-exposed groups.

Characterization of ATPases in the gill of freshwater mussel (Unio tigridis) and effects of ionic and nanoparticle forms of aluminium and copper.

Mussels are often used to monitor the aquatic systems for different ecological aims, as they are one of the best bioindicator animals. However, the characterization of biomarkers should be known before using them in environmental monitoring and toxicology studies. There is no study to our knowledge on the characterization of Na-ATPase and Ca-ATPase in tissues of freshwater mussel (Unio tigridis). Thus, this study was undertaken to characterize the optimum working conditions of Na-ATPase and Ca-ATPase in the gill of mussels, determining the highest levels of parameters (Na+, Mg2+, Ca2+, ATP, pH, temperature, enzyme amount, incubation time) to obtain maximum activity. The present study also aimed to investigate in vitro effects of ionic and nanoparticle (Al2O3, CuO) forms of aluminium and copper (0, 30, 90, 270 µg/L) on the activities of Na-ATPase and Ca-ATPase. Data showed that there was no ouabain-sensitive ATPase activity in the gill up to 10 mM ouabain concentrations. Na-ATPase and Ca-ATPase activities in the gill of control mussels were 5.124 ± 0.373 and 3.750 ± 0.211 µmol Pi/mg pro./h, respectively. Exposure to different concentrations of nanoparticles did not alter significantly (P > 0.05) the activities of Na-ATPase and Ca-ATPase in vitro, whereas the same concentrations of ionic aluminium and copper significantly decreased (P < 0.05) the enzyme activities. Data emphasized that there were different modes of action between ionic and nanoparticle forms of aluminium and copper. Data also suggested that in vivo studies should also be carried out to estimate better the effects of nanoparticle and ionic forms of metals on ATPases of U. tigridis.

Antioxidant system biomarkers of freshwater mussel (Unio tigridis) respond to nanoparticle (Al2O3, CuO, TiO2) exposures.

PURPOSE: Mussels are known as the natural filters of the aquatic systems and are accepted as one of the best bioindicator organism. There is no data on the response of Unio tigridis to metal-oxide nanoparticle (NP) exposures. This study aimed to investigate the response of the antioxidant enzymes of U. tigridis following exposure to NPs. MATERIALS AND METHODS: The mussels were exposed to different concentrations (0, 1, 3, 9 mg NP/L) of Al2O3, CuO and TiO2 NPs for 14 days and subsequently, the activities of CAT (catalase), SOD (superoxide dismutase), GPx (glutathione peroxidase), GST (glutathione S-transferase) and GR (glutathione reductase) were measured in the gill and digestive gland. Mussels were fed with cultured unicellular algae (Chlorella vulgaris) during experiments. RESULTS: Data showed that algae consumptions of mussels were not significantly (p>0.05) altered by NPs. However, all enzyme activities in the digestive gland and gill altered significantly (p<0.05) after NP exposures. The activities of CAT and SOD decreased, while the activities of enzymes belonging to glutathione metabolism (GPx and GST) increased in both tissues. CONCLUSION: This study representing the first record on the antioxidant system response of U. tigridis toward NP exposures suggests that NP toxicity should be investigated thoroughly in organisms and some regulations must be done on their usages.

Responses of biomarkers belonging to different metabolic systems of rats following oral administration of aluminium nanoparticle.

Nanoparticle (NP) forms of aluminium oxide (Al2O3) are used in various fields such as engineering, pharmacy, medicine etc. Compounds containing aluminium oxide NPs may present toxic effects after certain thresholds. Thus, the present study was carried out to determine the effects of Al2O3 nanoparticles (Al-NPs) in rats. For this aim, different doses (0, 0.5, 5, 50 mg/kg b.w./day) of Al NP (˜40 nm) were orally administered to female rats (Rattus norvegicus var. albinus) for 14 days and the response of several biomarkers such as activities of ATPases (total ATPase, Na,K-ATPase, Mg-ATPase) and acetylcholinesterase (AChE), levels of different glutathione forms and thiobarbituric acid reactive substances (TBARS) were measured in different tissues. Additionally, tissue accumulation of Al-NPs was demonstrated by a transmission electron microscope (TEM). The images showed the presence of Al-NP aggregates in all the tissues at all doses. The sizes of NP aggregates were dependent on NP doses and it was a bit more loose in the brain than in the liver and kidney. AChE activity in the brain decreased significantly at all NP doses, whereas TBARS levels in the liver did not alter significantly at any NP dose. Although there was no significant change in ATPase activities in the intestine at any NP dose, there were significant decreases in the kidney and brain. There were some variations in the levels of total glutathione (tGSH), oxidized glutathione (GSSG) and reduced glutathione (rGSH), though these variations were not significant (P > 0.05). Likewise, the ratio of rGSH/GSSG also did not differ significantly among NP doses and control. The brain seems most affected organ following Al-NP administration. This study demonstrated that most biomarkers in the tissues of rats were affected by Al-NP, showing the signal of toxic effects and suggests further studies to understand better the effects of Al NPs, especially in their use for pharmacology.

Response of the antioxidant enzymes of rats following oral administration of metal-oxide nanoparticles (Al2O3, CuO, TiO2).

Metal-oxide nanoparticles (NPs), as a new emerging technological compound, promise a wide range of usage areas and consequently have the potential to cause environmental toxicology. In the present work, aluminum (Al2O3), copper (CuO), and titanium (TiO2) nanoparticles (NPs) were administered via oral gavage to mature female rats (Rattus norvegicus var. albinos) for 14 days with a dose series of 0 (control), 0.5, 5, and 50 (mg/kg b.w./day). Enzyme activities of the antioxidant system such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST), and glutathione reductase (GR) in the liver were measured. Transmission electron microscope (TEM) images of the liver were taken to demonstrate NP accumulation and distribution in liver tissue. Data showed that all NPs caused some significant (P > 0.05) alterations in the activities of antioxidant enzymes. CAT activity increased after CuO and TiO2 administrations, while SOD activity decreased after Al2O3 administration. The activities of enzymes associated with glutathione (GR, GPx, GST) metabolisms were also significantly altered by NPs. GPx activity increased in rats received Al2O3, CuO NPs, while GR activity increased only by Al2O3. However, there were increases (TiO2) and decreases (CuO) in GST activity in the liver of rats. TEM images of the liver demonstrated that all NPs accumulated in the liver, even at the lowest dose. This study indicated that the antioxidant enzymes in the liver of rats were affected by all NPs, suggesting the antioxidant system of rats suffered after NP administration.

Serum biomarker levels alter following nanoparticle (Al2O3, CuO, TiO2) exposures in freshwater fish (Oreochromis niloticus).

Nanoparticles (NPs) are used in diverse field of technology and consequently are released to the environment, most ending up in water bodies. Because NPs have potential to cause adverse effects on the metabolisms of animals, the present study was carried out to help understanding their effects on fish metabolism. In this study, freshwater fish (Oreochromis niloticus) were exposed to aluminum oxide (Al2O3) (40 nm), copper oxide (CuO) (40 nm) and titanium dioxide (TiO2) (21 nm) NPs in differing concentrations (0, 1, 5, 25 mg/L) for 14 d. Following the exposures, the levels of glucose, cholesterol, triglyceride, blood urea nitrogen (BUN), creatinine, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), Na+, K+, triiodothyronine (T3), thyroxine (T4) and cortisol in the serum of fish were measured. The results of this study showed that there were significant alterations in the levels of some serum parameters. The levels of glucose, triglyceride, BUN, creatinine, K+, cortisol and T4 in the serum were changed following NP exposures, though there was no statistical difference in the levels of cholesterol, ALT, AST, ALP, Na+ and T3. Most striking data were obtained in the levels of BUN and creatinine, as their levels increased nearly 10 folds. Transmission electron microscope (TEM) images showed NP accumulation in tissues of fish even at the lowest exposure concentration. This study emphasized that NPs are not innocent compounds and can have hazardous effects when taken in substantial levels, suggesting there must be some criteria and limits in their usage and discharge to the environment. Nevertheless, more studies are needed to understand better their toxicities in different classes of animals.

Response of the antioxidant enzymes of the erythrocyte and alterations in the serum biomarkers in rats following oral administration of nanoparticles.

In this study, Al2O3, CuO and TiO2 nanoparticles (NPs) were administered to mature female rats (Rattus norvegicus var. albinos) via oral gavage (0, 0.5, 5, 50mg/kg b.w./day) for 14days to investigate their effects on 14 serum biomarkers and 4 antioxidant enzyme (catalase, superoxide dismutase, glutathione peroxidase, glutathione S-transferase) activities in the erythrocyte. Data showed that Al2O3 did not cause any significant (P>0.05) change in the parameters, except few cases, while CuO and TiO2 caused significant alterations in antioxidant system parameters of the erythrocytes. Activities of catalase and superoxide dismutase significantly decreased in CuO and TiO2 administered rats. Oppositely, glutathione peroxidase activity increased in CuO and TiO2 administered rats. There were no significant alterations in the activity of glutathione S-transferase in the erythrocytes. Levels of glucose, cholesterol, bilirubin, triglyceride, triiodothyronine (T3), estradiol, prolactin and immunoglobulin M (IgM) in the serum altered after some of NP administrations, whereas cortisol, protein, creatinine, blood urea nitrogen (BUN), thyroxine (T4) and immunoglobulin G (IgG) levels in the serum did not change significantly after any of NP administration. There were outstanding increases in the levels of bilirubin and prolactin and decreases in the levels of triglyceride and estradiol. The present study demonstrated that the antioxidant enzymes in the erythrocyte were generally affected from copper and titanium NPs, while aluminium and copper NPs caused more significant alterations in serum biomarkers.

Characterization of antioxidant system parameters in four freshwater fish species.

The potential use of antioxidant system parameters has gained considerable interest due to their pivotal role of detoxification mechanisms in environmental studies and culture fish point of view. Fish with different ecological needs may have different antioxidant capacity and response to environmental contaminants. Thus, the optimal working conditions and specific enzyme activities (Vmax and Km) of antioxidant system parameters (Superoxide dismutase, SOD; Catalase, CAT; Glutathione peroxidase, GPX; Glutathione reductase, GR and Glutathione S-transferase, GST) and glutathione (GSH) were determined in four commonly cultured freshwater fish species (tilapia; Oreochromis niloticus, carp; Cyprinus carpio, trout; Onchorhynchus mykiss and catfish; Clarias garipienus). Data showed that optimal concentrations of different buffers, pH and specific chemicals for each enzyme and GSH were similar in most cases for all fish species, except a few differences. The highest Vmax and Km values were found in carp for GPX and GST, though these values were the highest in tilapia, catfish and trout for CAT, SOD and GR, respectively. As a conclusion, optimization assays of these parameters in different bioindicator organisms based on their physiological and ecological differences may be useful for the aquatic ecosystem biomonitoring studies and also present fundamental data for utilization in aquaculture.

Low water conductivity increases the effects of copper on the serum parameters in fish (Oreochromis niloticus).

The conductivity is largely determined by ion levels in water, predominant ion being Ca(2+) in the freshwaters. For this reason, the effects of copper were evaluated as a matter of conductivity of exposure media in the present study. Thus, freshwater fish Oreochromis niloticus were exposed to copper in differing conductivities (77, 163 and 330 µS/cm), using acute (0.3 µM, 3 d) and chronic (0.03 µM, 30 d) exposure protocols. Following the exposure serum parameters of fish were measured. Data showed that there was no significant alteration (P>0.05) in serum parameters of control fish. However, activities of ALP, ALT and AST decreased significantly at the lower conductivities in chronic copper exposure, but not in acute ones. Protein levels did not differ significantly in any of the exposure conditions. However, Cu exposure at the lowest conductivity sharply increased the levels of glucose in the acute exposure, while there was no significant difference in the chronic exposure. Cholesterol levels decreased only at the lower conductivities in chronic exposure, but increased in acute exposure. Similarly, triglyceride levels increased in acute exposures and decreased in chronic exposures at the lowest conductivity. There was no change in Na(+) levels, while there was an increase in K(+) levels and a decrease in Ca(2+) level at the lowest conductivity of acute exposures. However, Cl(-) levels generally decreased at the higher conductivities of chronic exposures. There was a strong negative relationship between significant altered serum parameters and water conductivity. In conclusion, this study showed that copper exposure of fish at lower conductivities caused more toxicities, indicating the protective effect of calcium ions against copper toxicity. Data suggest that conductivity of water may be used in the evaluation of metal data from different waters with different chemical characteristics.