B-165. Evaluation of Bovine Gene Response to Fescue Toxicosis via Expression Microarrays

D. D. Tanaree1, J. Duringer1, D. Bohnert2, A. M. Craig1;
1Oregon State Univ., Corvallis, OR, 2Eastern Oregon Agricultural Res. Ctr., Oregon State Univ., Burns, OR.

Fescue toxicosis is a problem which causes over $1 billion in economic damage per year to livestock producers worldwide. Induced by ergot alkaloids, clinical signs can include fescue foot and summer syndrome (via vasoconstrictive effects), as well as reductions in reproductive fitness, weight gains, and milk production. Little is known about cellular mechanisms mediating these toxic effects. Liver biopsies were obtained from cattle (n=4) pre- and post-exposure (0 and 29 d) to feed containing 579 ppb ergovaline. Liver tissue RNA was extracted, reverse transcribed, and then hybridized to an oligonucleotide microarray chip. We evaluated the effects of ergovaline-based toxicosis on gene expression using an ANOVA model and false discovery rate (FDR) analysis. Results were validated with real-time PCR. There was a general pattern of downregulation in gene expression, which appears to be indicative of a stress or shock response. Amongst significantly (P < 0.05) upregulated genes, those dealing with toxin response and vasoconstriction were not the largest group of annotated genes to show such a response. Lipid metabolism and cell signaling genes were also affected, along with a number of sequences on the array which have not been annotated to date. Thus, exposure of cattle to toxic levels of ergovaline can result in widespread changes in gene expression in liver tissue beyond those related to clinical signs. Future studies will examine homology of non-notated sequences as well as explore the effects of other endophytic toxins.

126/B. Regulation of Virulence Determinants of Pathogenic Microorganisms - III

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