The degradation of myo®brillar proteins of rohu carp (Labeo rohita (Hamilton)) muscle was analysed after post-mortem storage. Muscle ®llets were kept either unfrozen at 2°C for up to 15 days or frozen at À8°C or À20°C for up to 6 months. A co-ordinated histochemical, biochemical and electrophoretic study showed a differential response of the carp muscle, revealing clear degenerative/ degradative changes speci®c to the post-mortem storage temperatures. The myo®brillar protein fractions, namely myosin light chains and a-actinin, showed degradative changes during the above storage conditions, whereas other protein fractions in the high-molecular-weight range fragmented to give lower-molecular-weight proteins. The importance of the post-mortem storage temperature for controlling the degradation of the myo®brillar proteins was emphasised. This is the ®rst report on this popular ®sh species, known for its culinary importance, showing that speci®c protein fractions of the myo®brils degrade during post-mortem storage.

From an histochemical and biochemical study on the fibre differentiation and muscle growth in common carp, Cyprinus carpio Var. communis, growth and development processes have been characterized on the basis ofdifferences in fibresize, fibre number, lipid content, succinicdehydrogenase (SDH) and myofibrillar adenosine triphosphatase (m-ATPase). A very early differentiation and zonal segregation of principal fibre types (red and white) and subsequent increase in muscle by their hypertrophy and hyperplasia was observed. These changes become pronounced after yolk sac absorption. The special character of the red muscle, as it develops from a superficial monolayered lateral sheet to a compact multicellular cone, was also investigated.

Response of tenotomized rat soleus muscle to denervation performed at different time intervals, has been investigated. Tenotomized muscles showed typical central core lesions seven days post-operatively. These were not observed in m-ATPase stained sections of simultaneously denervated and tenotomized muscles, and muscles denervated 24 h after tenotomy. Central core lesions were not prevented in muscles denervated 28 h after tenotomy, indicating that tenotomy effects responsible for central lesions are completed by this time. Myosin light chain pattern of muscles denervated 28 h after tenotomy, and tenotomized only were similar showing increased LC3/LC1 ratio. Simultaneously denervated and tenotomized muscle however showed all the three light chains relatively equal in quantity. The results suggest that elimination of neural activation within 28 h prevents myofibrillar loss and minimized other changes which occur due to tenotomy.

Myofibrillar proteins in the myotomal muscle fibre types of two freshwater teleosts, Heferopneusfes fossilis (Bloch) and Labeo rohita (Hamilton), were investigated. The fibre types were identified histochemically based on the reactivities of the enzymes SDH and m-ATPase. Electrophoretic analysis revealed distribution patterns of myosin light chains, tropomyosin, troponin, c-and m-protein; specific to the muscle fibre types. The results correlate well with the general pattern of myofibrillar protein distribution found in the skeletal muscles of higher vertebrates. The significance of the present findings are discussed with regard to histochemical, biochemical as well as functional properties of the muscle fibre types.

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