Transcriptional profiling during fetal skeletal muscle development of Piau and Yorkshire-Landrace crossbred pigs. Sus scrofa

The aim of this study was to identify differentially expressed genes and pathways in longissimus dorsi (LD) of pigs at 40 and 70 d of gestation (stages encompassing the transition from primary to secondary fiber formation) in U.S. commercial crossbred pigs (Yorkshire x Landrace) and Brazilian native Piau pigs. We confirmed the expression patterns for a subset of genes by qRT-PCR. Pathway analysis revealed functionally related genes, and indicated commonalities and differences between the breed types and developmental ages evaluated. Results from qRT-PCR analysis confirmed the expression patterns observed on the array for most of the genes tested (85%). This study reveals transcriptional profiles in LD at 40 and 70 d gestation for commercial and Piau pigs, which helps elucidate phenotypic differences between these breed types. Overall design: This study utilized the Swine Protein-Annotated Oligonucleotide Microarray which contains 20,400 70-mer oligonucleotides (http://www.pigoligoarray.org). Total RNA was isolated from fetuses obtained from gilts at each gestational age (n=3 crossbred gilts; n=4 Piau gilts) and RNA from 3 fetuses per litter was pooled. Samples were evaluated with a connected loop design using 13 slides such that six breed comparisons and seven age comparisons were performed. Fluorescence intensity data was LOESS normalized and analyzed with a mixed model.