Molecular Characterization of Cytochrome P450 1A (CYP1A) in Asian Sea bass (Lates calcalifer Bloch) and Its Application as a Biomarker in the Gulf of Thailand

This study focusses on aquatic pollution in Thailand, using induction of hepatic cytochrome P450 1A (CYP1A) in Asian sea bass as a biomarker to assess exposure to polyaromatic hydrocarbons (PAHs). Polyclonal antibodies (PAb) were raised against Asian sea bass CYP1A in mice. Western blot analyses revealed that these antibodies recognized a CYP1A protein in Asian sea bass treated with benzo[a]pyrene (BaP). The presence of a CYP1A orthologue in Asian sea bass liver was confirmed by isolating a partial cDNA, using a reverse transcriptase polymerase chain reaction (RT-PCR) approach. Quantitative RT-PCR analysis revealed that CYP1A mRNA was 2.5-fold higher in fish injected with BaP. The PAb were next applied on 15 different tropical fish species, caught off the Chonburi from three different stations: (1) Koh Loi, Si Racha, (2) Ao Udom and (3) Laem chabang. Although, species variation in CYP1A protein levels was observed, the data suggest that Si Racha and Ao Udom were more contaminated with PAH-type contaminants compared with Laem chabang. This study confirm studies in temperate waters that CYP1A could be used as early indicators of PAH-type exposure in Thailand, and that PAb against Asian sea bass is suitable for analyses of CYP1A in different tropical fish species.