Peroxisome proliferation and antioxidant enzymes in transplanted mussels of four basque estuaries with different levels of polycyclic aromatic hydrocarbon and polychlorinated biphenyl pollution

Abstract

We aimed to determine the effects of changes in polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) bioavailability on peroxisome proliferation and antioxidant enzymes to assess their potential use as pollution biomarkers. For this, mussels (Mytilus galloprovincialis) were sampled in Txatxarramendi and transplanted to Arriluze, Muskiz, and Plentzia (northern Spain), and vice versa. Arriluze was the most heavily polluted site, followed by Plentzia, Txatxarramendi, and Muskiz. Animals transplanted from a polluted station to a cleaner station lost contaminant load in three to six weeks, and when transplanted to a more polluted station, they accumulated PAHs and PCBs accordingly. Peroxisomal acyl-A oxidase (AOX) activity was the highest in animals from Arriluze, and animals transplanted to Arriluze showed increased AOX activity, reaching the levels of native mussels. Mussels from Txatxarramendi showed the lowest peroxisomal volume density (Vv_p). Among mussels from Txatxarramendi, only those transplanted to Plentzia showed increased Vv_p, whereas animals from Arriluze and Muskiz transplanted to Txatxarramendi after 2 d and six weeks, respectively, had decreased Vv_p. Two days after transplant, superoxide dismutase and glutathione peroxidase activities were significantly lower in mussels from Arriluze and Muskiz, respectively, than in those from Txatxarramendi and than in animals transplanted to Txatxarramendi from these stations. In conclusion, transplant experiments with mussels are useful to assess the effects of pollution. Peroxisome proliferation, measured as induction of AOX or increased Vv_p, shows great potential as a biomarker of pollution to be included in pollution monitoring programs. In the present work, we have demonstrated that peroxisome proliferation is a reversible phenomenon in mussels.