MYOSIN ISOFORMS IN SELECTED MUSCLE-FIBER TYPES OF THE POND LOACH MISGURNUS-FOSSILIS L

The main types of muscle fibre in the pond loach lateral musculature-r ed, intermediate and white, distinguished histochemically by myofibril lar ATPase activity-differ in the composition of their native myosin i soforms. However, each of these fibre types expresses a single myosin heavy chain (MHC) of similar electrophoretic mobility. The small diame ter fibres (referred to also as tonic-like) are distinct in myofibrill ar ATPase activity and seem to contain the unique type of MHC, which s uggests unique contractile properties for this fibre type.