Fish muscle, structure

The susceptibility to conformational changes is also governed by the formation of FA in the fish muscle. Structural changes during frozen storage in cod myosin, for instance, were noted to be induced by the addition of FA (Careche and Li-Chan,... 

Fig. 24. M-band structure from electron microscopy of both simple lattice and superlattice muscles. (A) 3D Reconstruction of fish muscle M-band. Three distinct layers were observed in the reconstruction, at each of the M-bridge levels M4, Ml, and M4 (M and B label the myosin filaments and M-bridges, respectively.) The observed 32-point group symmetry has been imposed on the 3D map. (B) Part of the M-band as modeled by Luther and Squire (1978). Ml and M4 bridges are seen connecting adjacent myosin filaments. Halfway along the M-bridges and running parallel to the myosin filaments are the M-filaments. M3 marks a further level of secondary Y-shaped bridges. (C) A slice...

When the structure in Fig. 29A is put into the fish muscle A-band unit cell (Fig. 29B note that the analysis of Hudson et al. [1997] defined the absolute orientation of the filament within the A-band lattice), it can be seen that the actin-binding sites on the myosi n heads are already close to... 

Al-Khayat, H. A., Morris, E. P., Powell, A. S., Kensler, R. W., and Squire,J. M. (2005a). 3D structure of vertebrate (fish) muscle myosin filaments by single particle analysis. 

Harford, J. J., and Squire, J. M. (1992). Evidence for structurally different attached states of myosin cross-bridges on actin during contraction of fish muscle. Biophys. /. 63, 387-396. 

Johnston, I.A. (1981b). Structure and function of fish muscles. Symposia of the Zoological Society, London 48,71-113. 

Dou, W., Zhao, Z.X., 1996. A study on bioaccumulation of BHC and DDT in fish muscles of different food structures from Baiyangdian Lake. Adv. Environ. Sci. (Chinese) 4(6), 51-56. 

The analyses carried out up to now on such extracts have been based upon differences of solubility (see p. 235). The discussion of the results obtained has made clear that a reinvestigation of these mixtures is necessary in order to define more accurately the structure proteins of fish muscle. Electrophoresis, which permits the analysis of such mixtures with a minimum of alteration, appears a particularly suitable method. It has been applied as yet only to carp muscle extracts of high ionic strength (Hamoir, 1951b, 1954, 1955). In view of the very constant electrochemical behavior of the muscle structure proteins (see Hamoir, 1953a), it seems safe to assume that similar results will be obtained with other fishes. The results already obtained will therefore be more extensively described. The slight difference in extractibility previously mentioned between white and red rabbit muscles (Crepax, 1952) suggests that a separate study of both fish muscles would also be desirable in this case, but it has not yet been undertaken. 

The various structural proteins of Fig. 11 and 12 may thus be isolated. Their behavior is very similar to the corresponding components of rabbit muscle, but their extractibility is quite different. Fish actomyosin goes easily into solution and rabbit actomyosin dissolves with difficulty. Fish tropomyosin can be selectively extracted at fi 1 and pH 5.2, whereas similar experiments on rabbit muscle reveal only a very small solubilization of this protein (Van de Bergh, unpublished results). Fish muscle is fundamentally similar to other striated muscles but seems to be characterized by a looser association of its structure components. 

The isolation of the proteins of fish muscle is still in its beginning, but is a necessary preliminary step to gain a deeper insight into the metabolism and structure of this tissue, thus providing a basis to attack the problems of storage. For the present, our description will be limited to some pure... 

The fibers of both white and dark muscles consist of bundles of striated myofibrils each containing thin and thick filaments and various subcellular structures such as the sarcoplasmic reticulum and other organelles (9,10,11). The size and shape of fish muscle fibers and myofibrils differ somewhat from the corresponding components of mammalian muscles (9,11). 

Many of the lipids found in nature are intimately bound to proteins and saccharides. The interactions within such structures are usually weak, but covalent bonds can occur (e.g., lipid inclusion in amylose or some lipid fractions in fish muscle tissue). During the processing and storage of food, the lipids are released and new bonds... 

Because phospholipids are typically the other main lipid class found in fish flesh, the leaner the fish and the higher the proportion that phospholipids contribute to total lipids. For this reason, phospholipids comprise almost 90% of total lipids of lean fish such as cod, with TAG contributing as little as about 1%. Due to anatomical and physiological reasons, the amount of structural lipids (phospholipids) varies between 0.3 and 0.5 per 100 g w/w of fish muscle and does not usually exceed 1% w/w. This is most likely the minimum level of phospholipids essential for the cell and organelle membranes, of which they are a major component. Phospholipids are the major lipid class in most Australian fish, and in mollusks and crustaceans, all of which are typically lean (Table 12.3). In contrast to finfish, which tend to store lipid as TAG, an increase in the lipid content of shellfish is usually due to an accumulation of polar lipids (Nichols et al., 1998). This is similar to the case in Antarctic krill Euphausia superba D.), the phospholipids of which serve as storage lipids along with TAG. 

Low field NMR has become a valuable tool in the research of muscle structure of meat and fish and has given valuable information about the water behaviour in such biological systems. The aim of this paper was to study the differences in farmed and wild cod muscle as indicated by low field relaxation measurements and how these results can be related to more traditional measurements of physical, chemical and sensory analysis and how different processing, such as filleting pre or post rigor mortis, salting and superchilling affected these parameters. 

A uniform expansion with porous structures such as restructured fish muscle (Wanget al, 2013). 

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