Comparative muscle transcriptome associated with carcass traits of Nellore cattle. Comparative muscle transcriptome associated with carcass traits of Nellore cattle

Background: Commercial cuts yield is an important trait for beef production, which affects the final value of the products, but its direct determination is a difficult procedure to implement in practice. The measurement of ribeye area (REA) and backfat thickness (BFT) can be used as indirect measure of meat yield. REA and BFT are important traits studied in beef cattle due to its strong implication in technological and nutritional characteristics of meat products, like muscularity degree and total body fat. Thus, the aim of this work was to study the Longissimus dorsi muscle transcriptome of Nellore cattle, associated with REA and BFT, to find differentially expressed genes, metabolic pathways, and biological processes that regulate these traits.Results: By comparing the gene expression level between groups with extreme genomic estimated breeding values (GEBV) one hundred and one differentially expressed genes for REA and, eighteen for BFT (FDR 10%) were identified. Functional enrichment analysis identified two KEGG pathways, MAPK (Mitogen-Activated Protein Kinase) signaling pathway and endocytosis pathway, and three biological process for REA. The MAPK pathway is responsible for fundamental cellular processes, such as growth, differentiation and hypertrophy. For BFT, eighteen biological process were found and grouped into 8 clusters of semantically similar terms. The differentially expressed genes identified in the biological processes for BFT were ACHE, SRD5A1, RSAD2 and RSPO3. The RSAD2 is associated with lipid droplet content and lipid biosynthesis.Conclusion: In this study genes, metabolic pathways, and biological processes, involved in differentiation, proliferation, cellular transport, as well as protein synthesis and degradation related to muscle mass and fat were identified. These results help us to better understand the different molecular processes involved in muscle and fat deposition of Nellore cattle.