Sequence analysis and Expression of Nramp-1 Gene in Bcg super(r) and Bcg super(s) Mice

Nucleic acid sequence of complemental DNA open reading frame for Nramp-1 gene was compared among DBA/2 (Bcg super(r)), C57BL/6 (Bcg super(s)) and C57BL/6- Bcg super(r) mice which was previously developed as M. avium-resistant mouse strain (Xu, et al. Veterinary Microbiology 50:73-79 (1996)). Total RNA was isolated from various organs of DBA/2, C57BL/6 and C57BL/6-Bcg super(r). Nramp-1 cDNA was constructed from their mRNAs by gene amplification (PCR) technique and their open reading frame sequences were compared. The results clearly showed that our C57BL/6-Bcg super(r) was almost identical with the DNA sequence of the DBA/2 mice. In contrast, C57BL/6-Bcg super(s) mice differed only on the substitution of adenine for guanine of the nucleic acid at position 596. This corresponded to the site of amino acid substitution (glycine to asparate) at position 169 in predicted NRAMP which had been reported. The expression of Nramp-1 mRNA was more prominent in spleens and livers and there appeared to be no significant difference among the strains of mice.