Ventricular myosin heavy chain isoform expression is altered in vitro in low score normal chickens.

The low score normal (LSN) chicken exhibits a genetic muscle weakness and altered in vitro myogenesis compared to the normal White Leghorn chicken. The ventricular myosin heavy chain isoform has been reported to be the initial muscle-specific contractile protein expressed during myogenesis. The goals of this study were to determine whether altered myogenesis of the LSN satellite cells in culture was accompanied by delayed ventricular myosin heavy chain expression and to further characterize the altered myogenic events exhibited by the LSN chicken. Immunocytochemical and ELISA analyses were employed to document the temporal expression of the ventricular myosin heavy chain during LSN chicken myogenesis. Satellite cells derived from the LSN chicken pectoralis major exhibited lower (P </= 0.05) expression of ventricular myosin heavy chain during proliferation and differentiation in culture than did satellite cells derived from White Leghorn chickens. Low score normal cells failing to express the ventricular myosin heavy chain generally remained mononucleated and unfused, whereas cells that were multinucleated appeared to express ventricular myosin heavy chain regardless of the avian source. These results suggest that the altered myogenesis observed in LSN chickens is associated with delayed ventricular myosin heavy chain expression.