Changes in the structure and function of the epaxial muscle of rainbow trout (Oncorhynchus mykiss) in relation to ration and age

Larsson

et al. 1995

Fish Physiol Biochem

Self Cite

Enzymatic changes that occur in the white somatic muscle of rainbow trout (Oncorhynchus mykiss) in response to spawning were investigated, and the evenness of their distribution across the ventral-dorsal plane of this muscle was assessed. Four enzymes that are involved in energy metabolism were measured (phosphofructokinase: glycolytic capacity, 3-hydroxyacyl-CoA dehydrogenase: β-oxidation, citrate synthase: citric acid cycle, cytochrome oxidase: oxidative capacity). The enzyme activities were followed in different parts of the white muscle of non-spawning female rainbow trout from May, four months after their first spawning, until December, at second spawning. Samples were taken from white epaxial muscle along the lateral line, on the dorsum, and in between. Samples were also taken from red muscle of non-spawning fish. The isoforms of myosin heavy chains (MyHC) were electrophoretically identified on 6% SDS-PAGE gel to study possible changes in contractile properties of the muscle.Transformation from the non-spawning to spawning phase was associated with dramatic changes in the activity of the enzymes studied in white muscle: glycolytic capacity decreased to less than half, whereas oxidative metabolism increased about two- to four-fold in all areas. Significant quantitative differences in enzyme activities were found between the three epaxial muscle areas: in the non-spawning fish lateral line samples differed from those taken in the other two areas, whereas in spawning fish the dorsal sample difered from the other two. No difference in the expression of MyHC-isoforms was found between spawning and non-spawning fish. Co-expression of both slow and fast isoforms was found in single fibres isolated from red muscle.The results show that the energy metabolism in white muscle of domestic rainbow trout is altered during spawning; i.e., the metabolism becomes increasingly aerobic, with an increased capacity for fatty acid utilization, concomitant with phenotypic changes associated with sexual maturation. These changes are especially pronounced in ventral, superficially located fibres.

Section: Discussionsupporting

confidence: 80%

Section: Myosin Heavy Chain Isoformssupporting

confidence: 76%

Section: Muscle Samples and Enzymatic Analysesmentioning

confidence: 99%

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Spawning induces a shift in energy metabolism from glucose to lipid in rainbow trout white muscle

Larsson

et al. 1995

Fish Physiol Biochem

Self Cite

“…In agreement with previous studies, the present experiment found that mean fibre area increases with fish weight. 35,36 This suggests that other factors, co-varying with fibre size or fibre density, are responsible for the variation in gaping observed in the present study.…”

Section: Discussionmentioning

confidence: 56%

Temporal variation in muscle fibre area, gaping, texture, colour and collagen in triploid and diploid Atlantic salmon (Salmo salar L)

Bjørnevik

Espe²,

Beattie

et al. 2004

J Sci Food Agric

Diploid and triploid Atlantic salmon were reared for 32 months in seawater, from October 1998 to January 2000. During this period of time, four samplings were taken to study differences in quality traits and chemical components in the flesh between diploid and triploid Atlantic salmon. Season was found to be the dominant factor explaining the variation in flesh quality traits in both triploid and diploid fish. Ploidy affected the majority of investigated variables while body size had lesser impact. Triploid Atlantic salmon had fewer small muscle fibres and up to 23% larger mean cross-sectional muscle fibre area than diploids. Triploids also displayed more gaping, softer fillet texture, lower post mortem end pH, darker (L value) and redder (a value) flesh colour, and more soluble and less insoluble collagen compared with diploid fish. No effect of ploidy was found on crude chemical composition. Furthermore, a negative relationship was found between gaping score and muscle fibre area, and a weak positive correlation was found between fibre density and texture firmness. However, when body size and sampling time was included in the statistical model, this relationship between gaping and fibre area became very weak, and the relationship between texture and fibre area was completely negated. This suggests that intra-species variation in both texture and gaping is more related to season and body size than to average muscle fibre area size.

“…13 The deep white skeletal muscle, anatomically distinct from red muscle and accounting for most of the muscle mass, is composed only of fast-twitch glycolytic ®bres. 14,15 In sardine and tuna the gel-forming ability of minced muscle and myo®brillar proteins from red muscle is lower than that for white muscle. 16,17 However, Lefevre et al 18 demonstrated that brown trout myo®brils from white and red muscles can produce gels of equivalent rigidity after heating at 0.6 M KCl and pH 6.0.…”

Section: Introductionmentioning

confidence: 99%

Thermal gelation of brown trout myofibrils from white and red muscles: effect of pH and ionic strength

Lefèvre¹,

Fauconneau²,

Ouali³

et al. 2002

J Sci Food Agric

The effects of pH and ionic strength on the thermal gelation of brown trout myo®brils from white and red muscles were analysed by thermal scanning rheometry. The highest gelation ability was obtained at low pH (around 5.6) whatever the ionic strength. No effect of ionic strength was observed at pH 5.6; however, at pH 6.0, lowering the salt (KCl) concentration to 0.3 M or less improved the characteristics of the gels formed. The effects of pH and ionic strength on myo®brils from both muscle types appeared to be similar, but red muscle proteins were less sensitive to changes in their physicochemical environment. Consequently, the differences between muscle types appeared to be dependent on pH and ionic strength. Solubility measurements revealed large differences between muscle types and between different pH values. Ultrastructural observations con®rmed that different kinds of gels were formed depending on the physicochemical conditions and muscle type origin. INTRODUCTIONThe thermal gelation properties of myo®brillar proteins have been studied in a large variety of animals. 1 The capacity to produce gels at relatively low temperature is speci®cally observed in aquatic organisms, and this property has been used for processing ®sh myo®brils in surimi-like products. Thermal gelation properties based on interactions between proteins are very dependent on the physicochemical environment, especially pH and ionic strength. 1 Both ionic strength and pH act on myo®bril dissociation prior to heating and on protein charges, which in turn affect protein±protein and protein±solvent interactions during heating. Susceptibility of thermal gelation to physicochemical conditions varies between animal species. Proteins from ®sh are much more sensitive to changes in pH and ionic strength than those from mammals and birds and can form a gel only in a narrow range of pH and salt concentration. 2 Amongst ®sh species, myosin from cold-water ®sh is more sensitive to changes in the physicochemical environment than myosin from warm-water ®sh. 3 Fish muscle proteins, especially myosin, show an optimal thermal gelation around pH 6.0. 3±6 As the pH increases above this value, the transition temperature of myosin decreases, 5 and this is associated with protein destabilisation and consequently a lower gel-