Candidate genes validation for intramuscular fat content of Nellore Cattle.

Intramuscular fat is an important factor for the sensory quality and value of meat. However, in tropical breeds such as Nellore, the lower marbling capacity represents a challenge for its positioning in premium markets. Marbling score (MS) and the total lipid (TL) determination methods are complementary methodologies for measuring beef intramuscular fat. Longissimus thoracis samples from the 24 most extreme steers (out of 189 steers) for MS (high = 12 and low = 12) and TL (high = 12 and low = 12) traits were collected to: 1) validate in Nellore cattle differentially expressed genes for MS and TL traits found in the literature in other populations using real-time PCR, and 2) verify if differentially expressed genes were translated into differentially expressed proteins through advanced mass spectrometry (LC-MS/MS). Significant differences in the expression levels of the genes FABP4, DGAT1, DGAT2, BARX2, STAT5A, and SDC were observed in the group with high intramuscular fat content. These genes play important roles in lipid metabolism, adipogenesis and muscle development. Proteins encoded by genes (PRDM1 and COL1A2) regulated by the transcription factor STAT5A were differentially expressed and probably play a key role during intramuscular fat deposition. Our results confirm that the genes FABP4, DGAT1, DGAT2, STAT5A, and BARX2 validated here can potentially be used as biomarkers for intramuscular fat in Nellore cattle.