Expression stability of reference genes in the skeletal muscles of beef cattle

The objectives of this study were to evaluate the relative expression stability of five candidate reference genes in the semimembranosus (SM) and longissimus thoracis (LT) of beef steers, heifers and young bulls. The mRNA levels of Beta-Actin, eukaryotic initiation factor-2B Subunit 2, glyceraldehyde-3-phosphate dehydrogenase, peptidylprolyl isomerase-A and succinate dehydrogenase complex-subunit A were quantified using real-time polymerase chain reaction (qPCR). The combined analysis using the geNorm algorithm revealed that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and eukaryotic initiation factor-2B subunit 2 (EIF2B2) were the most stable gene pairs. However, individual experimental conditions showed that succinate dehydrogenase complex-subunit A was most stably expressed in bulls and heifers SM, and in bulls and steers LT. Glyceraldehyde-3-phosphate dehydrogenase was most stably expressed in bull SM, steer SM, bull LT and heifer LT. The expression stability ranking order differed between experimental conditions, but all genes had low expression variability. Therefore, using the two most stable reference genes, namely GAPDH and EIF2B2, would result in more accurate normalizations for quantitative real-time PCR studies in the SM and LT muscles of beef cattle. The need for prior evaluation of candidate reference genes in different muscles and sex groups of beef cattle is thus emphasized by the present results. Key words: Bovine, gene expression, longissimus thoracis, normalization, reference genes, semimembranosus, geNorm.