Bioaccumulation and the expression of hepatic cytochrome P450 genes in marine medaka(Oryzias melastigma) exposed to difenoconazole

This study was conducted to assess the effects of difenoconazole(DFZ), a triazole fungicide,on the hepatic biotransformation system and its bioaccumulation in marine medaka(Oryzias melastigma). Fish were exposed to DFZ(1, 10, 100, 1000 ng/L) for 180 days. The results showed that:(1) The m RNA levels of hepatic CYP1A1, CYP1 B, CYP1C1, CYP27 B and CYP3A40 were up-regulated, but those of CYP3A38 and CYP27A1 were down-regulated.(2) The activity of ethoxyresorufin-O-deethylase(EROD) and the content of reduced glutathione(GSH) in the liver were increased in the DFZ-treated groups, and glutathione S-transferase(GST) activity was increased in the 100 and 1000 ng/L groups.(3) DFZ was accumulated in the muscle and the biological concentration factors in the 10, 100, and1000 ng/L groups were respectively 149, 81 and 25. These results suggested that long-term exposure to DFZ at low concentrations would result in a bioaccumulation of this compound and disturb the biotransformation system.