Toxicopathology and expression of a CYP1-like gene in gills and digestive gland of wild Mediterranean mussel (Mytilus galloprovincialis) from sites with different contamination profiles and exposed to B[a]P

) did not significantly modulate the CYP1-like expression in either tissue, despite evidence for DNA damage and histopathological alterations. However, wild mussels collected from estuarine sites with previously described distinct contamination profiles showed different expression patterns in the gills, suggesting that CYP1-like transcription may be influenced by environmental variables other than known AhR agonists in vertebrates, even though these may cause adverse effects. They also indicate that comparisons with vertebrate models should be made with caution, given possible differences in phase I bioactivation and its regulation between lophotrochozoans and higher eumetazoans.