New methods to use fish cytochrome P4501A to assess marine organic pollutants

A new methodology has been developed to assess cytochrome P4501A expression in two South Atlantic Spanish fish, guilthead seabream (Sparus aurata) and grey mullet (Liza aurata), used as pollution bioindicators. Degenerate oligos were used to amplify by reverse transcription and PCR (RT-PCR) specific cyp1A cDNA sequences, used subsequently to design specific primers to get the full cDNA by rapid amplification of cDNA ends. A new assay has been developed to quantitate cyp1A expression by RT-PCR in an automated DNA sequencer. The effect of beta-naphthoflavone inducing biotransformation has been used to compare three distinct pollution biomarkers: EROD activity, ELISA determination of CYP1A, and 2-aminoanthracene (2-AA) activation. Immunodetection by ELISA or Western blot was inconsistent in S. aurata and L. aurata. EROD activity yielded satisfactory results; the higher induction was observed by bioactivation of 2-AA to mutagens detected with strain BA149 of Salmonella typhimurium, in agreement with the high sensitivity previously described for this biomarker. The present paper summarizes the current status of our research.