Skeletal muscle development in normal and double-muscled cattle

Area of Science:

• Animal Science
• Developmental Biology
• Genetics

Background:

• Myostatin is a key regulator of skeletal muscle growth.
• Mutations in myostatin lead to a 'double-muscled' phenotype in various species.
• Understanding the impact of myostatin mutations on prenatal muscle development is crucial.

Purpose of the Study:

• To investigate the effects of a myostatin gene mutation on prenatal muscle development in cattle.
• To compare muscle development parameters between normal-muscled (NM) and double-muscled (DM) animals.
• To analyze muscle weight, fiber type, and fiber size during bovine prenatal development.

Main Methods:

• Analysis of muscle weight, fiber type (enzyme histochemistry, MHC immunocytochemistry), and average fiber area at four gestational ages.
• Comparison between NM and DM bovine fetuses.
• Assessment of myosin heavy-chain (MHC) isoform localization.

Main Results:

• DM animals exhibited greater muscle weight (M. vastus lateralis and M. vastus medialis) throughout prenatal development compared to NM animals.
• The percentage of type 1 muscle fibers was consistently lower in DM than NM animals.
• DM muscle showed MHC isoform patterns indicative of delayed development, with differential regulation of muscle fiber size based on fiber type.

Conclusions:

• The inactivating myostatin mutation in DM animals is associated with significant alterations in skeletal muscle development.
• Changes in muscle fiber type composition and fiber size are observed during prenatal development in DM cattle.
• This study highlights the critical role of myostatin in regulating bovine muscle growth and differentiation.