Lack of effect of beta-naphthoflavone on induction of Nramp genes in adult rainbow trout Oncorhynchus mykiss

Natural resistance-associated macrophage protein (Nramp) genes in rainbow trout, Oncorhynchus mykiss, were identified and characterized. The greatest mRNA level encoding these genes was in the developing ovary of rainbow trout. We evaluated the response of these genes to a certain aromatic hydrocarbon receptor (AHR) agonist. Adult rainbow trout were treated with β-naphthoflavone (BNF) (50 and 100 mg/kg) for 48 h. Using reverse-transcriptase polymerase chain reaction with ovary and head kidney RNA and specific α and β Nramp primers, a 400 bp Nramp-α- and a 400 bp Nramp-β-specific cDNA were obtained. There were no changes in the α and β Nramp mRNA levels in the ovary following BNF administration. CYP1A1 mRNA was increased in the ovary and kidney, suggesting the presence of AHR in rainbow trout ovary, while the AHR agonist produced no effect on Nramp mRNAs.