EVIDENCE FOR THE EXISTENCE OF CYTOCHROME-P450 GENE FAMILIES (CYP1A, 3A, 4A, 11A) AND MODULATION OF GENE-EXPRESSION (CYP1A) IN THE MUSSEL MYTILUS SPP

The presence and expression of four gene families of the cytochrome P4 50 multi-gene family (CYP450) was investigated in the digestive gland of M. edulis using Southern and Northern blot analysis. The cDNA probe s employed were for CYP1A1 (pfP(1)450-3(1), 1.5kb from rainbow trout), CYP3A (phPCN12, human), CYP4A1 (2.1kb, rat) and CYP1A1 (1.9kb, human) . Single hybridising mRNAs of approximately 2.1kb were seen for all pr obes, indicating presence and expression of genes from or similar to t he four families. Hybridisation on Southern blots was demonstrated for CYP3A and CYP11A, confirming the presence of related CYP genes. The f ormer gave a strong band at about 4.5kb and a weak one at 7.3kb, and t he latter a single band at 13kb. The detection of CYP3A-like sequences is consistent with the reported presence of testosterone 6-beta-hydro xylase activity in M. edulis. Marked variation in levels of CYP1A-like mRNA were seen in mussels from several sites in the Venice area (UNES CO-MURST Venice Lagoon Project), indicating modulation of gene express ion. Some correlation with contaminant exposure was seen, indicating p otential for use of this measurement as a biomarker for organic pollut ion.