Effect of Maternal Nutrition on the Transcriptome of Fetal Muscle in Sheep

Maternal nutrition during different stages of pregnancy can induce remarkable phenotypic changes in fetal tissues, which in turn can have lifelong implications. The objective of this study was to evaluate the effect of different maternal diets on the transcriptome of fetal muscle in sheep. Ewes were bred to a single sire and from days 67±3 of gestation until necropsy (days 130±1), they were fed one of three diets: alfalfa haylage (HY; fiber), corn (CN; starch), or dried corn distiller’s grains (DG; fiber plus protein plus fat). Longissimus dorsi muscle tissue from individual fetuses were pooled and then analyzed by RNA sequencing. Reads were mapped to the ovine genome using Tophat, and the resulting alignments were used to reconstruct transcript models using Cufflinks. Differential gene expression was analyzed using edgeR package. Significant gene expression differences were found between CN and the other two treatments. A total of 860 and 1,578 transcript units out of 17,544 showed differential expression (FDR <0.05) between DG vs CN, and HY vs CN, respectively. Notably, the expression of most genes in fetuses was decreased by maternal CN diet. Pathway analysis revealed that several Gene Ontology terms (e.g., embryonic morphogenesis, muscle fiber development, contractile fiber), InterPro entries (e.g., several tubulin-like and calponin-like motifs), and KEGG pathways (e.g., focal adhesion, gap function) were enriched (FDR <0.05) with differentially expressed genes. Many of these pathways are closely related to muscle development. Overall, our findings provide evidence that maternal diet can modulate gene expression in fetal muscle in sheep.