2007 Annual Report 1a.Objectives (from AD-416) The objectives of this cooperative research project are (1) to identify bull calves from the ISU Ankeny Holstein population that represent different genotypes for a polymorphism in the promoter region of the PrP gene and (2) to identify differences in gene expression in the central nervous system between cattle affected, and not affected, with BSE using microarray technology. 1b.Approach (from AD-416) A polymorphism in the putative PRNP promoter region that shows a significant association with BSE susceptibility was recently identified in cattle. Genomic DNA will be extracted from Holsteins representing each of three sub-populations within the ISU Holstein herd. Genotypes will be determined for the PrP promoter region polymorphism and animals selected for BSE inoculation. For gene expression studies, CNS will be harvested from cattle affected and non affected with BSE immediately following euthanasia. Total RNA will be extracted from CNS tissues for gene expression analyses using the Affymetrix platform. Comparisons will be made between BSE affected and non affected animals in order to identify gene expression profiles associated with BSE. 3.Progress Report This report serves to document research conducted under a specific cooperative agreement between ARS and the Iowa State University entitled "Identification of Cattle with Different Genotypes for BSE Inoculation". Additional details of research can be found in then report for the parent project 3625-32000-086-00D, Transmission, Differentiation, and Pathobiology of Transmissible Spongiform Encephalopathies. The objectives of this cooperative research are (i) to identify bull calves from the Iowa State University Ankeny Holstein population that represent different genotypes for a polymorphism in the promoter region of the PrP gene, and (ii) to identify differences in gene expression in the central nervous system between cattle affected, and not affected, with BSE using microarray technology. NADC has taken possession of 40 bull calves representing different PrP genotypes that will be used for this cooperative research. Analysis of gene expression profiles comparing BSE affected and non-affected animals has not yet been initiated. During the past year there were regular contacts with the cooperator. These contacts included phone calls and e-mail correspondence.