MyHCs developmental expression patterns and its effect on muscle fibre characteristics in pig

Abstract

This study comprehensively explored muscle fibre characteristics and expression patterns of myosin heavy chain (MyHC) family in skeletal muscles of Large White and Mashen pigs exhibiting differences in muscle fibre development in postnatal muscle growth. Muscle fibre density and diameter were analysed using haematoxylin and eosin staining. The expression patterns of MyHCI, MyHCIIa, MyHCIIx and MyHCIIb were detected by quantitative real-time polymerase chain reaction. The muscle fibre diameter increased and density decreased gradually with aging. In individuals of the same age, the muscle fibre diameter was significantly lower and density was significantly higher in Mashen than in Large White pigs. The MyHCI expression increased, whereas that of MyHCIIa first increased and then decreased. The expression of MyHCI and MyHCIIa was significantly higher in Mashen. The expression of MyHCIIx and MyHCIIb decreased with increasing age; their expression was significantly lower in Mashen pigs. Muscle fibre diameter was negatively correlated with MyHCI expression and positively correlated with MyHCIIx and MyHCIIb expression (except the expression of MyHCI in psoas major). Muscle fibre diameter, muscle fibre density, and MyHCs expression follow certain patterns in skeletal muscles. These results provide valuable information for understanding the molecular mechanism responsible for pig growth performance and meat quality.