Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 14, 2001
Publication Date: N/A
Technical Abstract: Nitric oxide (NO), an important component of the innate immune response, is derived from L-arginine in a reaction catalyzed by nitric oxide synthase (NOS). Although constitutive expression of NOS proteins occurs in various cells, professional phagocytes such as macrophages contain an inducible form of this enzyme (iNOS or NOS2). Induction of NOS2 requires exogenous stimulation of the macrophage by factors such as IFN- and LPS, and result in the production of high concentrations of reactive nitrogen intermediates (ROI) and subsequent microbial killing. We identified 9 SNPs within the bovine NOS2 (bNOS2) gene by sequencing PCR amplification products of a portion of the gene homologous to human NOS2 intron 7, using genomic DNA from a panel of 96 sires from 17 popular breeds of U.S. beef cattle. Polymorphisms were verified by MALDI-TOF mass spectrometry as well as by segregation in the MARC reference population. Four SNPs were further analyzed for haplotype structure in U.S. beef cattle and four haplotypes were identified (1 through 4), with allele frequencies of 0.51, 0.34, 0.14, and 0.01, respectively. Haplotype 1 was present in all 17 breeds tested, whereas haplotype 4 was only present in the Brahman and Beefmaster breeds tested. We plan to perform a series of experiments designed to determine whether these haplotypes are associated with increased/decreased NOS2 activity and ultimately bacterial killing. Results of these studies may provide an additional tool for producers to use in the selection of cattle superior in the control of pathogenic bacteria.