Cytochrome P450-Dependent Mixed FunctionOxidases (MFO) System Dynamics During the PolyAromatic Hydrocarbon (PAH) Metabolism in GreenMussel Perna Viridis (Linnaeus, 1758)

摘要

Polyaromatic hydrocarbons (PAH's) are the prominent and most common pollutants inaquatic environments, particularly in marine water. The discharge of hydrocarbons intothe sea might be of great concern for marine species living close to dumping sites. There-fore, toxicological properties of hydrocarbons released into marine environments needto be evaluated. PAH pollution potential may be predicted by assessing the induction ofhepatic cytochrome P450-associated enzyme activity. The inducibility and activity ofphase I reduction nicotinamide adenine dinucleotide phosphate, reduced (NADPH) cyto-chrome c reductase (CCR), cytochrome c oxidase (COX) and three CYP450 isoforms(benzyloxyresorufin - O-dealkylase (BROD], ethoxyresorufin-O-dealkylase [EROD] andmethoxyresorufin-O-dealkylase [MROD]) enzymes were measured in the hepatic S9fraction prepared from Perna viridis collected from three sites: a highly oil-polluted site(Kasimedu fishing harbor, Rayapuram, Chennai [Station]]); a moderately polluted off-shore site, about 3 Km away from this area [Station 2]; and the least oil-polluted site(Vellar estuary, Parangipettai [Station 3], which was a reference site.) The levels ofBROD (CYP2B6), MROD (CYPIA2) and EROD (CYP1A1) in the tissues of green musselwere measured using Spectro-Fluorometer SL-174, (ELICO, India). All the MFOenzymes exhibited a hierarchical dose-dependent activity in response to oil pollution inthese study areas. Samples from the heavily oil-polluted (Kasimedu Station-1 and Sta-tion-2) areas exhibited greater activity of all enzymes than the least oil-polluted (Vellarestuary) reference area. Among the enzymes analyzed, the MROD activity was best cor-related with the level of hydrocarbon contamination (P < 0.05). Therefore MROD can beconsidered as a robust biomarker for petroleum hydrocarbons in P. viridis.