Slow-type C-protein in dystrophic chicken fast pectoralis muscle.

C-protein isoform expression in hereditary dystrophic chicken skeletal muscle was compared with that in normal chicken muscle during postnatal development by immunocytochemical and immunoblot methods. In the pectoralis muscle (PM) of both normal and dystrophic chicken, slow- and fast-type C-proteins were coexpressed in the vast majority of myofibers at neonatal age, but the slow C-protein disappeared, leaving continued expression of only the fast-type C-protein as muscle development progressed up to 2 weeks posthatch. In the dystrophic chicken PM, however, myofibers containing slow-type C-protein reappeared about 1 month posthatch and increased in number with the progression of muscular dystrophy. We conclude that C-protein isoform expression in dystrophic myofibers resembles that in neonatal myofibers and that the expression of slow-type C-protein can be seen as a marker for chicken muscular dystrophy.