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Frontiers in veterinary science
Frontiers
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Abstract: |
The toxic waste and pollutants of heavy metals continuously pollute freshwater aquatic
reservoirs, which have severe implications on aquatic life and human health. The present
work aims to evaluate trace elements (Zn, Mn, Cu, Cd, and Pb) along with three sites,
Mariout Lake, Abbassa, and River Nile Aswan in Egypt, using Nile tilapia (Oreochromis
niloticus) as bioindicator. The quality assurance, health-risk assessment, sodium dodecyl
sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), quantitative polymerase chain
reaction (qPCR), and micronucleus test were performed to investigate the effect of
different trace elements on Hsp70 gene level and micronuclei formation. We observed the
highest expression of Hsp70 protein band of 70 KD and stress-responsive Hsp70 gene in
the liver followed by gills of Nile tilapia caught from Mariout and Abbassa, but the lowest
expression was in Nile tilapia caught from Aswan. Obvious micronuclei were observed
under the microscope in erythrocytes, and their number was gradually decreased in the
following manner: Mariout > Abbassa > Aswan. Noticeably, Cu, Zn, and Mn contents
were low. Still, Pb and Cd contents were higher than the toxicity level recommended by
the Food and Agriculture Organization (FAO), The World Health Organization (WHO), and
the European Commission (EC). These results showed that Hsp70’s appearance at the
two levels of mRNA and protein is an effective indicator for aquatic pollution besides the
aberration at the chromosome level represented in the micronucleus test. Furthermore,
these results showed that Nile tilapia of the Aswan region had comparatively low trace
elements contamination and were suitable for consumption
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