Tissue dose, DNA adducts, oxidative DNA damage and CYP1A-immunopositive proteins in mussels exposed to waterborne benzo[ a]pyrene

Abstract

A collaborative study was performed on Mediterranean mussels ( Mytilus galloprovincialis) exposed to a wide dose-range (0.5–1000 ppb) of benzo[ a]pyrene (B[ a]P). We selected this model polycyclic aromatic hydrocarbon in order to confirm the formation of a specific DNA adduct, previously detected in gill DNA, and to clarify the in vivo effects of this mutagenic chemical requiring host-metabolism in mussels. B[ a]P concentration reached consistently higher values in the digestive gland than in other analyzed tissues of mussels exposed to B[ a]P for 2 or 3 days. With the exception of some values at 1000 ppb of B[ a]P, DNA adduct levels increased significantly with the dose in gills and digestive gland and ranged from 0.054 to 0.789 adducts per 10 8 nucleotides (mean values per dose-point). Conversely, more complex dose-response relationships were found by detecting in parallel the levels of an oxidative DNA lesion (8-OHdG) and of CYP1A-immunopositive proteins (the latter measured in the digestive gland only). Overall, the formation of DNA adducts, the evidence of oxidative DNA damage, and changes in CYP1A-immunopositive protein levels support the hypothesis that B[ a]P can induce DNA damage in mussels through a number of different molecular mechanisms.