Impact of energy restriction during late gestation on muscle and blood transcriptome of beef calves
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Maternal nutrition during gestation has long-term effects on skeletal muscle development of the offspring. In this thesis, we studied the effect of energy restriction during late gestation on gene expression in the blood and muscle tissues of preconditioned beef calves. The first chapter corresponds to a literature review in which we describe aspects related to this research, such as muscle and immune system development, gene expression, and the use of RNA-seq data to answer complex biological questions. The second chapter describes a research project in which, multiparous cows were divided into two groups: cows fed 70% and 100% of their energy requirements during the last third of gestation. Blood and muscle samples were collected from the offspring, and total RNA was extracted and sequenced (RNA-seq). Finally, statistical analyses were performed to identify differentially expressed genes as an effect of maternal energy restriction, overrepresentation of related biological functions, and to construct gene-gene networks. A total of 160, 164, and 346 DEG (q-value < 0.05) were identified in the skeletal muscle for the effects of diet, sex, and diet-by-sex interaction, respectively. For blood, 452, 1392, and 155 DEG were identified for the effects of diet, time, and diet-by-time interaction, respectively. For skeletal muscle, results based on diet identified genes involved in the muscle metabolism. On muscle, from the 10 most DEG down-regulated in the energy-restricted group (REST), we identified 6 genes associated with muscle metabolism and development, SLCO3A1, ATP6V0D1, SLC2A1, GPC4, RASD2, and SLC2A1. On blood, among the top 10 DEG, we found genes related to response to stress overexpressed in the REST after weaning, such as SOD3 and INO80D, and to immune response down-regulated in the REST after vaccination, such as OASL, KLRF1, and LOC104968634. Among the DEG identified in both blood and muscle, including VAT1, CABLES1, SLC20A2, ILF3, and QDPR were down-regulated in the muscle and up-regulated in blood, and SPAG17 and LOC107131247 were down-regulated in both.
Therefore, the findings support the hypothesis that alterations in the intra-uterine environment can alter the gene expression of muscle and blood on the offspring which and, consequently, modify postnatal development.