Gene expression in muscle and adipose tissue of steers classed as Choice or Standard

摘要

Beef tenderness is a leading influence in consumer decisions to choose beef. Insufficient marbling and subsequent lower quality grades, lack of a uniform product, reduced or insufficient tenderness can negatively impact beef acceptability. The objective of this study was to investigate differences in gene expression, metabolism and intercellular signaling in the muscle and proximate intermuscular adipose tissue in carcasses of differing quality grades. Previous research evaluated Longissimus lumborummuscle sampled at slaughter and a significant number of differences were observed between Choice and Standard carcass samples (1,258 genesO.Ol). In this study, RNA was harvested from Longissimus thoracis muscle and associated adipose tissue at slaughterand individual samples were sequenced using RNAseq. Differential expression was determined using edgeR and P-values were adjusted using the Benjamini-Hochberg method. A corrected P-value of 0.005 and one fold change defined significant differential expression. When comparing muscle from Standard and Choice carcasses, 15 genes were down regulated and 20 were up regulated. The insulin receptor substrate 1 (IRS 1) gene was the only known functionally important gene to be differentially expressed. There were 49 down-regulated genes and 113 up-regulated genes in the comparison between adipose tissue from Standard and Choice carcasses. The function of these genes was primarily metabolism of fat and energy. This potentially demonstrates that intermuscular adipose tissue can play a bigger role in meat quality and tenderness levels than currently known.