Gene expression profiles in muscle of black Iberian pigs supplemented with organic selenium compared with sodium selenite in finishing diets
Supplementation with organic Se provides positive benefits through increased bioavailability and absorption compared with inorganic Se. The objective of this study was to evaluate the effect of different sources of Se on muscle gene expression in finishing black Iberian pigs. The finishing experimental period started when the animals reached 80 kg and ended at slaughter at approximately 120 kg. The treatments consisted of a standard finishing diet supplemented with organic Se (0.2 ppm Se as Sel-Plex®; SP, Alltech Inc) or inorganic Se (0.2 ppm as sodium selenite; SS). Skeletal muscle samples were obtained at slaughter and stored in RNA later until analysis. Total RNA was isolated from samples (n=5/trt) using standard methods and was hybridized to the Affymetrix Porcine Genome array. Expression data were statistically analyzed using the GeneSpring GX 10.0 software in which SP was directly compared to SS using a t-test. Statistical differences were declared at P < 0.05 without considering a fold change cut-off. Genes differentially expressed were imported into Ingenuity for biological function analysis. Results indicated that 1205 genes (757 up- and 448 down-regulated) were differentially expressed (P < 0.05) in SP relative to SS. The biological function analysis resulted in several enriched functions related to muscle development. Among these, positive activation of lipid metabolism, cellular and tissue development (Z score > 2) were the most relevant to the study. Further analysis of the biological functions identified specific genes associated with the regulation of beta-oxidation and overall energy metabolism including CPT1C, SCD5, MYO1B and CAST among others. In addition, upstream molecule analysis indicated that more than 30 genes were controlled by TGFB1 (Transforming growth factor beta 1), which is closely related to Se in the regulation of oxidative stress. In conclusion, this study shows evidence of multiple molecular mechanisms affected by SP in skeletal muscle of black Iberian pigs that relate to performance and meat quality.
Keywords: Se, swine, gene expression, microarray, muscle