Correlation between Polyaromatic Hydrocarbons (PAHs) Discharges at El-Manzala Wetland with the Relative Gene Expression of CYP19 Gene of the Nile Tilapia (Oreochromis. niloticus)

El-Manzala Wetland is known to be of the most significant sources of inexpensive different fish species for human consumption in Egypt. The Lake receives pollution from various sources; domestic wastewater, industrial wastewater, and agricultural drainage directly without any treatments, which leads to many environmental disorders. The following research was conducted for lake water quality evaluation and how it impacts the expression of the aromatase (CYP19a&b) genes in Oreochromis niloticus tissues at different locations of El-Manzala Lake. Sampling was done during the summer of 2018 when water and fish samples were collected from five different locations of El-Manzala Lake. It was found that the studied locations recorded hazardous concentrations of polyaromatic hydrocarbons (PAHs) that may cause significant defects to aquatic organisms except in the reference location and affect the expression of CYP19a&b genes. The relative gene expressions of CYP19a in the ovary and the testis were measured and recorded in positive ranges but revealed the controversial expression pattern of CYP19b gene in the brain tissues. Our results revealed that PAHs discharges at El-Manzala Lake are correlated with the gene expression of CYP19 genes. The current findings suggested a correlation between biomarkers response and wastewater exposure as stressors. Besides, the assessed multiple general health indicators give prospective insights for Nile tilapia adaptive pattern and monitoring of pollution of freshwater ecosystems.