Hindawi Publishing Corporation Comparative and Functional Genomics Volume 2012, Article ID 756284, 11 pages doi:10.1155/2012/756284 Research Article Functional Genomic Analysis of Variation on Beef Tenderness Induced by Acute Stress in Angus Cattle Chunping Zhao, 1, 2 Fei Tian, 2 Ying Yu, 2, 3 Juan Luo, 2 Apratim Mitra, 2 Fei Zhan, 2 Yali Hou, 2 George Liu, 4 Linsen Zan, 1 M. Scott Updike, 2, 5 and Jiuzhou Song 2 1 College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi 712100, China 2 Department of Animal & Avian Sciences, University of Maryland, College Park, MD 20742, USA 3 Department of Animal Breeding and Genetics, College of Animal Sciences, China Agricultural University, Beijing 100193, China 4 Bovine Functional Genomic Laboratory, Animal and Natural Resources Institute, USDA-Agricultural Research Service, Beltsville, MD 20705, USA 5 Standerds Division, USDA-Agricultural Marketing Service-National Organic Program, Washington, DC 20250, USA Correspondence should be addressed to Linsen Zan, zanls@yahoo.com.cn and Jiuzhou Song, songj88@umd.edu Received 29 November 2011; Accepted 19 January 2012 Academic Editor: Giulia Piaggio Copyright © 2012 Chunping Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Beef is one of the leading sources of protein, B vitamins, iron, and zinc in human food. Beef palatability is based on three general criteria: tenderness, juiciness, and flavor, of which tenderness is thought to be the most important factor. In this study, we found that beef tenderness, measured by the Warner-Bratzler shear force (WBSF), was dramatically increased by acute stress. Microarray analysis and qPCR identified a variety of genes that were differentially expressed. Pathway analysis showed that these genes were involved in immune response and regulation of metabolism process as activators or repressors. Further analysis identified that these changes may be related with CpG methylation of several genes. Therefore, the results from this study provide an enhanced understanding of the mechanisms that genetic and epigenetic regulations control meat quality and beef tenderness. 1. Introduction Beef is a source of high-quality nutrition for human pop- ulations. Beef palatability is generally determined by three general criteria: tenderness, juiciness, and flavor. Of these factors, beef consumers usually consider tenderness as the most important palatability trait leading to a good eating experience [1–3]. Inconsistency in tenderness has been reported as the most important factor in determining con- sumer satisfaction with beef quality [4–9]. It is well known that beef tenderness is influenced not only by genetic factors but also environmental aspects. Many studies have been performed on beef quality and tenderness, identifying various important candidate genes [10, 11], quantitative trait loci (QTL), and single-nucleotide polymorphisms (SNPs) [12–20]. High-throughput transcriptomics and proteomics were also used to explore the mechanism of controlling beef quality and tenderness [21–27]. These researches focused much attention on genetic factors influencing beef tender- ness. Anecdotally, farmers found that beef produced by cattle which suffered from acute stress, such as injury, surgery, or hardware disease, has much lower quality compared to beef from normal cattle [28–31]. This phenomenon like hardware disease may occur often; therefore the underlying mechanism needs to be explored to better understand what drives beef tenderness and to ultimately improve profitability and efficiency of beef production. So far, we have not seen research which examines the mechanisms of beef quality alteration attributed to acute stress. In this experiment, we found an acute stress event that altered beef tenderness.