Identification and mapping of differentially expressed genes in fetal and postnatal pig skeletal muscle

Fetal myogenesis and postnatal skeletal muscle hypertrophy in growing pigs are critical yet poorly understood processes. Global gene expression analyses can identify key genes and pathways controlling these processes. In addition, integration of gene expression data with genome map information will facilitate identification of genes controlling economically important trait phenotypes. This study was designed to identify differentially expressed genes in developing pig skeletal muscle and locate them on the pig genome map. The specific objectives were: (1) Identify differentially expressed genes in hind limb skeletal muscle of pigs at 60 days of gestation and 7 weeks of age; and (2) Determine the map locations for differentially expressed genes. A combination of differential display RT-PCR, cDNA microarray analysis and oligonucleotide microarray analysis were used to identify differentially expressed genes. In total, over 200 differentially expressed genes were revealed and expression patterns for eight genes were evaluated by relative real time RT-PCR, confirming differential expression for seven of them. Twenty-four genes were mapped to 13 different pig chromosomes using the INRA-University of Minnesota (IMpRH) 7,000 rad radiation hybrid panel. This study represents a first step toward characterizing the transcriptional profile of developing pig skeletal muscle and it improves the porcine-human comparative map.