Preliminary Study On Metabolic Mechanism Of Benzo(a)pyene In Black Porgy (Sparus Macrocephalus)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitoust pollutants in the marine environment and many PAHs are carcinogenic and mutagenic. The research on the metabolic mechanism of Benzo(a)pyrene (BaP) in marine fish is one of the hotspots and difficulties in the ecotoxicological research area. This study integrated the chemical, ecotoxicological and biochemical methods to discuss the mechanism of metabolism and biotransformation of black porgy (Sparus macrocephalus) exposed to BaP primarily. Meanwhile, field experimental study has been done to investigate the different susceptibility between black porgy and siganussp (Siganus oramin) with different living habits and feeding habits.The following results were obtained: 1. Exposed to the lower BaP concentration (0.5μg/L and 1.0μg/L), it was found that the hepatic EROD activities were induced simultaneously with the increase of the accumulation of BaP in liver, which showed a significant positive correlation. But the hepatic GST activities had no significant change during exposure period. The concentrations of 3-OH BaP in bile had no significant variation in the early exposure period, significant variations were found after 7days expsoure.The results indicated the hepatic CYP1A enzymes were induced in the metabolic process of BaP and developed the detoxicification effect on BaP, consequently, kept from the genotoxicity occurring.2. Exposed to the higher BaP concentration (2.0μg/L and 5.0μg/L) , Black Porgy showed a rapid increase on the accumulation of BaP in the liver, reached the peak after 12h exposure, and then it decreased gradually. Meanwhile, the concentrations of 3-OH BaP increased rapidly and reached its peak after 4-7d exposure. And the strong significant induction of EROD activities was found at the 12h exposure. This indicated that the bioaccumulation under the high concentration exposure could enhance the rate of BaP biotransformation in liver. However, the high concentration of BaP and its metabolites in liver may inhibit the activity of CYP1A, which would cause lesions in fish.