Aroclor 1254 and Benzo(a)Pyrene Induced Cyp P450 (A1) in Nile Tilapia Larvae

Background and Objective: Many organisms, including fish, respond to pollutant insult by changing the expression of genes, particularly those for xenobiotic metabolism. The ultimate objective of this study was to provide a practical monitoring tool for assessing exposure to pollutants using Nile tilapia (Oreochromis niloticus) as an indicator species. Materials and Methods: A total of (60) 6-7 days post fertilized prefeeding larvae of Nile Tilapia (Oreochromis niloticus) were used as a model species and exposed to different sublethal concentrations of Aroclor 1254 at a concentration of 16 mg/L and Benzo[a]pyrene, at a concentration of 1.6 mg/L in the laboratory using a quantitative polymerase chain reaction (qPCR) with power SYBR Green II master mixes. Primer sequences of cytochrome P450 A1 gene (CYP 1A forward and reverse) that were already optimized and passed quality criteria were used in the assay. Transcript expressions of genes were measured using RT-qPCR. Results: The results showed that each chemical induced significant CYP 1A mRNA gene expression patterns after 24 hrs of exposure, involving biological signaling pathways of aryl hydrocarbon receptor pathways, which are known to respond to chemicals such as PCBs and PAHs compared to control. Each chemical generated a different level of fold change of gene expression in prefeeding larvae of Nile tilapia. Conclusion: Thus, this indicates that a standard PCR array such as the one described here, could be used to extend these studies to wild samples (samples from different waterbodies), in order to determine whether contaminants are likely present in harmful concentrations.