Assessment of Hepatotoxicity Induced by Aluminum Oxide Nanoparticles in Oreochromis niloticus Using Integrated Biomarkers: Exposure and Recovery.

The hepatotoxic impacts of 2, 4, and 8 mg/L of Al2O3 nanoparticles (31.4 ± 4.8 nm) were evaluated in Oreochromis niloticus after 7 days of exposure and 15 days of recovery periods. The biochemical analysis of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase in plasma showed significant increases in both 4 and 8 mg/L Al2O3 NPs exposed groups. The antioxidant biomarkers showed concentration-dependent elevations in catalase, superoxide dismutase, glutathione peroxidase activities, and thiobarbituric acid reactive substances levels. Glutathione reduced contents showed significant reductions in both 4 and 8 mg/L Al2O3 nanoparticles exposed groups. Several hepatic histopathological alterations were recorded ranging from adaptive responses (e.g. melanomacrophages aggregation) to permanent damage (e.g. necrosis). The recovery period using toxicant-free water led to an obvious reduction in the Al content in liver, liver and antioxidant enzymes in addition to regressive histopathological alterations based on the frequency of alterations occurrence and the extent of affected areas.

Assessment of metal pollution impacts on Tilapia zillii and Mugil cephalus inhabiting Qaroun and Wadi El-Rayan lakes, Egypt, using integrated biomarkers.

Qaroun and Wadi El-Rayan lakes are exposed to a huge amount of discharges from different sources and numerous anthropogenic activities. Therefore, the present work aimed to evaluate the impacts of metal pollution on two wild fish species; Tilapia zillii and Mugil cephalus collected from lake Qaroun (eastern and western parts) and Wadi El-Rayan lakes (upper and lower lakes). Accumulation of metals (Cu, Zn, Cd, and Pb) in water, sediment, and five vital tissues as well as metal pollution index (MPI), contamination factor (CF), and pollution load index (PLI) were integrated as metal pollution biomarkers. Generally, these integrated endpoints had the same trend and indicated that the eastern part of lake Qaroun was the most polluted site followed by the lower lake of Wadi El-Rayan. To assess the environmental genotoxicity, the percentage DNA damage in different tissues of both fish species was estimated using the comet assay technique. The percentage of DNA damages showed tissue-, species- and site-specification. Hazard index (HI) has been used as an evaluation index for human health associated with fish consumption at the studied sites. This index showed that all metals were in the safe limits at normal consumption levels while adverse health effects are expected to occur at the subsistence consumption level. The safe HI for each metal at normal consumption level does not neglect that the combined cumulative risk impact of all metals is a sign of warning and the health of fish consumers nearby contaminated sites is threatened.

Comparative Assessment of Genotoxic Impacts Induced by Zinc Bulk- and Nano-Particles in Nile tilapia, Oreochromis niloticus.

Fish were separately exposed to 1/2 LC50/96 h values of bulk-Zn and nano-Zn for 7, 14, and 28 days. The induction of micronuclei (MN) and other eight nuclear abnormalities in erythrocytes showed marked time and size dependence. The frequencies of all nuclear anomalies were progressively elevated (p < 0.05) with increasing the time of exposure to both bulk-Zn and nano-Zn. Throughout the study periods, fish exposed to nano-Zn showed the maximum elevation in all studied nuclear anomalies. Based on the fragmented DNA values, both Zn forms induced tissue-specific DNA damage as following gills > liver > muscles. Moreover, nano-Zn exposed groups revealed a maximum percentage of DNA damage among all studied groups, especially after 14 days. The percentage of DNA damage was decreased in all tissues on the 28th day, which reflected the presence of an effective repair mechanism. Finally, nano-Zn exhibited more genotoxic effects than that of its bulk counterparts.