Molecular Cloning of CYP1A1 in the Rockfish (Sebastes schlegeli) and Effects of PCB on Its Gene Expression

Abstract

Most studies on the interaction of environmental pollutants with fish hepatic cytochrome P450 have been focused on the induction of this enzyme system. There have been attempt to use the P450 level and ethoxyresorufin-O-deethylase (EROD) activity in fish as a biochemical markers to determine the extent of exposure to enzyme inducing chemicals (e.g. dioxins). However, It is suggest that CYP1A1 can be induced or inhibited by some xenobiotics such as polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs). Furthermore, relationship between chemicals structure or dosages and gene expression remains unclear. A cDNA library and cloned a partial CYP1A1 mRNA of rockfish, which is a commercially important marine species in Korea, was constructed to use them for monitoring studies. The deduced amino acid sequence of CYP1A1 mRNA showed a high homology to those of other fishes (81%). CYP1A1 mRNA transcript from hepatic tissue has been extracted for the northern blot analysis. Effects of PCB 153 and Aroclor 1260 on CYP 1A1 mRNA expression in vivo with juvenile rockfish were examined using the northern blot analysis. CYP 1A1 mRNA in the juvenile rockfish injected with 0.16 mM/kg of PCB 153 increased at 24 hrs and decreased at 72 hrs after injection. However, Aroclor 1260 showed difference in effects of gene expression. The expression level of CYP 1A1 mRNA decreased at all the time after injection in both dosages of Aroclor 1260. These results indicate that the expression of CYP 1A1 mRNA is different between single PCB species and PCB mixtures.