Abstract
This study used qRT-PCR to examine variation in the expression of 13 myogenes during muscle development in four prenatal periods (21, 40, 70 and 90 days post-insemination) in commercial (the three-way Duroc, Landrace and Large-White cross) and local Piau pig breeds that differ in muscle mass. There was no variation in the expression of the CHD8, EID2B, HIF1AN, IKBKB, RSPO3, SOX7 and SUFU genes at the various prenatal ages or between breeds. The MAP2K1 and RBM24 genes showed similar expression between commercial and Piau pigs but greater expression (p < 0.05) in at least one prenatal period. Pair-wise comparisons of prenatal periods in each breed showed that only the CSRP3, LEF1, MRAS and MYOG genes had higher expression (p < 0.05) in at least one prenatal period in commercial and Piau pigs. Overall, these results identified the LEF1 gene as a primary candidate to account for differences in muscle mass between the pig breeds since activation of this gene may lead to greater myoblast fusion in the commercial breed compared to Piau pigs. Such fusion could explain the different muscularity between breeds in the postnatal periods.
Highlights
Myogenesis is a prenatal process that involves the formation of muscle fibers through changes in gene expression and cell phenotype, and is influenced by genetic and environmental factors (Te Pas et al, 2005)
The size and number of muscle fibers determine muscle mass since skeletal muscle growth depends on the number of fibers formed during myogenesis and on postnatal muscle hypertrophy, which is limited by physiological and genetic factors (Rehfeldt et al, 2000)
Primary muscle fibers are formed de novo in the early stages of myoblast fusion and secondary fibers use the primary fibers as a template in a second wave of differentiation (Rehfeldt et al, 2000; Te Pas et al, 2005); the lat
Summary
Myogenesis is a prenatal process that involves the formation of muscle fibers through changes in gene expression and cell phenotype, and is influenced by genetic and environmental factors (Te Pas et al, 2005). The changes in gene expression associated with muscle development and growth have been examined in different breeds of pigs at various prenatal ages (Te Pas et al, 2005; Cagnazzo et al, 2006; Murani et al, 2007; Sollero et al, 2011; Zhao et al, 2011). The analysis of changes in myogenic gene expression during the prenatal period, when the two waves of myoblast fusion occur, can be very important for understanding the biochemical differences that contribute to distinct interbreed variations in the degree of muscularity and meat quality.
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