Antioxidant markers in gills, liver and muscle tissue of the African Sharptooth Catfish (Clarias gariepinus) exposed to subchronic levels of Ibuprofen and Dibutyl phthalate

Is the trend toward a sustainable green synthesis of copper oxide nanoparticles completely safe for Oreochromis niloticus when compared to chemical ones?: using oxidative stress, bioaccumulation, and histological biomarkers

Scientists worldwide have noticed that cutting-edge technologies can be used to produce nanoparticles (NPs) in a sustainable and environmentally friendly way, instead of the old methods. However, the effectiveness of this approach for aquatic environments and species still needs to be determined. Therefore, this study aims to compare between the toxicity of green and chemically synthesized copper oxide nanoparticles (GS and CS) CuO NPs at two different concentrations on Nile tilapia (Oreochromis niloticus) using various biomarkers. CuO NPs' formation was proved, and their different characterizations were recorded. Then, the fish samples were randomly allocated in glass aquaria into five groups: one acted as a control group, and the other groups were exposed to two concentrations (25 and 50 mg/L) of GS-CuO NPs and CS-CuO NPs, separately, for 4 days. After the experimental time, in all groups that were exposed to two concentrations of both synthesized CuO NPs, the results revealed that glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), and thiobarbituric acid reactive substances (TBARS) levels were elevated in the liver and gills compared to glutathione reduced (GSH) content, which showed a significant decline. Bioaccumulation of Cu was more prevalent in the liver than in the gills, and the highest bioaccumulation capacity was more evident in the groups exposed to CS-CuO NPs. Moreover, the bioaccumulation of Cu caused severe histological changes in the liver and gills. In conclusion, the results suggested that GS-CuO NPs revealed less toxicity than CS-CuO NPs to the examined fish. However, they are still toxic, and their toxic effect cannot be overlooked.

A study to assess the health effects of an anticancer drug (cyclophosphamide) in zebrafish (Danio rerio): eco-toxicity of emerging contaminants

Cyclophosphamide (CP) is widely used for treating various kinds of cancer. Because of its high intake, metabolism and excretion, these anticancer medications have been detected in the aquatic environment. There is very limited data on the toxicity and effects of CP on aquatic organisms. The present study aims to assess the toxic effect of CP on certain oxidative stress biomarkers (superoxide dismutase-SOD, catalase-CAT, glutathione peroxidase-GPx, glutathione-GSH, glutathione S-transferases-GST and lipid peroxidation-LPO), protein, glucose, metabolising enzymes (aspartate aminotransferase-AST, alanine aminotransferase-ALT), and ion-regulatory markers (sodium ions-Na⁺, potassium ions-K⁺, and chloride ions-Cl^-), and histology in the gills and liver of Danio rerio at environmentally relevant concentrations (10, 100 and 1000 ng L^-1). Exposure to CP for 42 days led to a significant decrease in SOD, CAT, GST, GPx and GSH levels in the gills and liver tissues of zebrafish. The level of lipid peroxidation in the gills and liver tissues of zebrafish was significantly increased compared to the control group. Chronic exposure significantly changes protein, glucose, AST, ALT, Na⁺, K⁺ and Cl^- biomarkers. Fish exposed to different levels of CP showed necrosis, inflammation, degeneration and hemorrhage in the gills and hepatic tissues. The observed changes in the studied tissue biomarkers were proportional to both dose and time. In conclusion, CP at environmentally relevant concentrations causes oxidative stress, energy demand, homeostasis disturbances, and enzyme and histological alterations in the vital tissues of zebrafish. These alterations were similar to the toxic effects reported in mammalian models.

The antioxidant defense capacities and histological alterations in the livers and gills of two fish species, Oreochromis niloticus and Clarias gariepinus, as indicative signs of the Batts drain pollution

The impacts of the Batts drain on two chronically exposed fish (O. niloticus and C. gariepinus) were assessed using multiple biomarkers. Concentrations of metals in water and sediments (Cu, Zn, Fe, Cd, Pb, and Al) showed significant elevations near the Batts discharges (site 2) compared to the reference site (site 1). The liver and gills of fish collected from site 2 showed marked elevations in the catalase, superoxide dismutase, glutathione peroxidase, and thiobarbituric acid reactive substance levels. In addition, significant reductions in glutathione-reduced contents were also recorded. Tissue and species-specific antioxidant responses were associated with excessive generations of reactive oxygen species, which were visualized fluorescently. Various histological alterations were observed in the gills and livers of both species. These alterations varied between compensatory responses (ex: epithelial thickening and lifting) and irreversible damage (ex: necrotic degeneration). Based on the level of lipid peroxidation and the frequency of histopathological modifications, O. niloticus demonstrated greater resistance to the same level of pollution than C. gariepinus. Using integrated biomarkers to evaluate the real impacts of untreated discharges of the Batts drain is applied for the first time on the selected fish species at the studied sites.