LAUSR

The objective of this study was to investigate early postmortem (0.5 h) gene expression in beef Longissimus thoracis (LT) muscles from carcasses with NORMAL (<5.8) and HIGH (>5.9) ultimate pH (pHu). A total of 53 transcripts were differentially expressed (P-value <.05): 40 showed up-regulation and 13 showed down-regulation in HIGH pHu carcasses. Four up-regulated (PDK4, GADD45B, MAOA, METTL21C) genes were confirmed (P < .05) by q-PCR. HIGH pHu samples resulted with lower values in glycolytic potential and AMP-activated protein kinase activity compared to NORMAL at 0.5 and 24 h postmortem (P < .05). Functional pathway analysis showed that calcium transport and GADD45 signaling pathways are associated with the development of HIGH pH meat. Genes involved in stress-related signaling, such as GADD45B, METTL21C and MAOA were overexpressed. These genes are involved in stress signaling that might be affecting Ca2+ transport and oxidative metabolism pathways in HIGH pH muscles.