Introduction
Myostatin, or growth and differentiation factor 8 (GDF8), is a member of the
transforming growth factor-b superfamily; it functions as a negative regulator of
skeletal muscle development and growth in mammals (McPherron and Lee 1997).
The myostatin gene consists of three exons and two introns in all species studied
(Bellinge et al. 2005). Although myostatin is principally found in skeletal muscle, it
has also been localized to adipose tissue, where it serves as a negative regulator of
preadipocyte differentiation (Feldman et al. 2006). The effects of the myostatin gene
were first described in mice, where loss of myostatin expression in knock-out mice
was associated with both an increase in the number of muscle fibers (hyperplasia)