Lack of eect of beta-naphtho¯avone on induction of Nramp genes in adult rainbow trout Oncorhynchus mykiss A.K. Dasmahapatra, B.A.B. Wimpee, K.J. Budsberg, M.O. Dorschner, R.B. Phillips, R.J. Hutz * NIEHS Marine and Freshwater Biomedical Sciences Center, University of Wisconsin-Milwaukee, Milwaukee, WI 53204, USA Accepted 5 May 2000 Abstract Natural resistance-associated macrophage protein (Nramp) genes in rainbow trout, Oncor- hynchus mykiss, were identi®ed 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 b-naphtho¯avone (BNF) (50 and 100 mg/kg) for 48 h. Using reverse-transcriptase poly- merase chain reaction with ovary and head kidney RNA and speci®c a and b Nramp primers, a 400 bp Nramp-a- and a 400 bp Nramp-b-speci®c cDNA were obtained. There were no changes in the a and b 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 eect on Nramp mRNAs. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Nramp; CYP1A1; Ovary; Rainbow trout; BNF; RT-PCR The identi®cation and characterization of genetic factors in¯uencing natural sus- ceptibility to infectious diseases can provide new insight into the basic mechanisms of host defense against infections. Natural resistance-associated macrophage protein (Nramp), a product of the Nramp gene, regulates macrophage activation for anti- microbial activity against intracellular pathogens. Studies in mammals showed that Marine Environmental Research 50 (2000) 147±151 www.elsevier.com/locate/marenvrev 0141-1136/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0141-1136(00)00113-6 * Corresponding author. Tel.: +1-414-382-1726.