Seasonal depending expression of CYP1A in the hepatopancreas of Merluccius merluccius and Mullus barbatus at the mouth of the river Bojana

Abstract

In order to ,issess effects of environme ntal pollutants on aqu at ic ecosystem s, different biomarkers may be exa mined. The pha se I biotransforma t ion e nzymes, notab ly CYP l A, definitely belong to t he most sensitive fish biomarker s known at present. CYP l A is a well-established biomarker of exposure of fish to xenobiotic compounds. The CY P l A protein le vels can be determined immunologicaly , using mono- or polyclonal antibodies with ELISA, Western-blotting or histochemic al technique s. Generally, a good correlation is observed between CYP I A mRNA , protein le ve l s and CYP I A activity. ln this work we per fo rm ed Weste r-b lot analys is and our aim was to characterize the in du c ti on of CYPIA in he patopanc reas of the European hake-Merluccius mer /ucc ius and Red mul let-Mu l/us barbatus and in winter and spring at the mouth of th e river Bojana. Both species are of considerable commercial import ance Whereas intersp ecies differences in protein profiles were established, no qualitative or quantitative intraspecies or seasonal variations in protein profiles were observed. Western blot analysis with a polyclonal antibody to CYP1A reve aled the CYP I A expression in both examined fish species in winter at the very low level. However, the relative concent!"ations of CYP I A were increased in sprin g. The apparent initiation of the defens e response in fish suggests that the contamin ants present in seawater have an eco toxico logic al potentia l. These findings could be interpreted as an ea rly­ warning signal for the deleter ious effects of the pollutants. The higher le vel of CYP l A in spr in g could be connecte d with increased antopo genic ac ti v ity at the mouth of the river Bojana in this part of the year.