The utilization of cytochrome P4501A mRNA in Limanda limanda (Dab) as a monitor of chemical exposure in the North sea

Various components of the mixed function oxidase system in the livers of Limanda limanda (Dab) were utilized to monitor the extent of pollution in the German Bight area of the North Sea. The elevation of ethoxyresorufin-O-deethylase and cyano-ethoxycoumarin dealkylase activities in hepatic microsomes in samples taken from sites close to shore indicate significant pollution by chemicals capable of inducing cytochrome P4501A in the liver. Cytochrome P4501A mRNA was also elevated in the livers of fish taken at inshore sites. The measurement of mRNA for this form of cytochrome P450 can therefore be utilized as a biochemical monitor of chemical pollution. The same biochemical markers were utilized to assess hydrocarbon pollution in the area of an abandoned oil rig site, and the results indicated that contamination with inducing compounds was negligible. These results indicate that the measurement of cytochrome P4501A in a number of ways, including the assessment of its mRNA level, is a valid indicator of the exposure of fish to certain environmental pollutants.