INDUCTION OF CYTOCHROME P4501A MESSENGER-RNA BY 3-METHYLCHOLANTHRENE IN RED-SEA BREAM PAGRUS-MAJOR

The induction of cytochrome P4501A (CYP1A) mRNA in red sea bream Pagru s major was investigated using CYP1A cDNA. The CYP1A cDNA was derived from a 3-methylcholanthrene (MC)-inducible mRNA of P. major. CYP1A mRN A was induced in the liver, gill, gut and kidney after an intraperiton eal injection of 3-MC, although the induction levels of mRNA were diff erent among these organs. Results of the time course experiment showed that the CYP1A mRNA content rapidly increased immediately after the 3 -MC injection, then showed a slight decrease prior to a further increa se until at least 70 h after the injection. The CYP1A mRNA content inc reased in a concentration-dependent manner when fish were treated with various concentrations of 3-MC. The effect of water temperature on th e induction of CYP1A mRNA was examined. The level of mRNA content was approximately double in fish maintained at 15 degrees C of sea water t han those at 11 degrees C and 19 degrees C. However, the induction lev els of CYP1A mRNA were still higher in fish at 11 and 19 degrees C tha n in the control fish. These results suggested that the CYP1A mRNA may be useful as a biological indicator of the presence and concentration of chemical pollutants.