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  • 1
    ISSN: 1573-5168
    Keywords: stress ; growth hormone ; cortisol ; glucose ; rainbow trout ; fasting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plasma growth hormone concentrations of rainbow trout,Oncorhynchus mykiss, fasted for six weeks, were significantly (p 〈 0.01) higher than in comparable fed animals; in the fasted fish, the levels fell progressively following acute stress (by displacing the fish within their home aquarium), with significant differences from pre-stressed fish evident between one and thirty-two hours after application of the stressor. Plasma growth hormone concentrations also fell significantly in the fed group, but differences were evident only between two and eight hours after stressor application. Plasma cortisol concentrations in pre- and post-stressed fed and fasted fish were similar. There was a bimodal response to stressor application in both groups, with significantly higher values relative to the pre-stressed sample evident one and eight hours after disturbance, but not after two, four or thirty-two hours. The changes in plasma cortisol levels between the initial (09:00h) sample and the sample taken eight hours later resembles the diet pattern seen in trout given access to self-demand feeders. Plasma glucose concentrations in pre-stressed fed animals were higher than in pre-stressed fasted fish. This relationship was also evident between one and four hours and thirty-two hours after stressor application. The post-stress rise in plasma glucose concentration was evident between one and four hours in the fed group, and between four and eight hours in fasted fish. The diel changes in plasma growth hormone and glucose concentrations could not be attributed to normal circadian patterns, and there was no apparent correlation between changes in plasma growth hormone and cortisol concentrations. There was a significant inverse correlation between plasma glucose and growth hormone concentrations when the total data set were analyzed, but these correlations were not apparent when the treatment groups were analyzed separately.
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  • 2
    ISSN: 1573-5168
    Keywords: salmon ; cell culture ; polyunsaturated fatty acid ; metabolism ; phospholipid classes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The incorporation and metabolism of (n-3) and (n-6) polyunsaturated fatty acids were studied in a cell line derived from chum salmon heart (CHH-1). Supplementing media with 25 μM fatty acid considerably altered the cellular fatty acid composition but did not affect the lipid class composition or cause the appearance of cytoplasmic lipid droplets. CHH-1 cells exhibited considerable Δ-6-desaturase activity but showed no preference between (n-3) and (n-6)PUFA substrates. CHH-1 cells also possess Δ-5-desaturase activity which showed preference towards (n-3)PUFA, but Δ-4-desaturase activity was totally absent. Elongation of 20-carbon PUFA was especially active in CHH-1 cells with 22-carbon PUFA being specifically incorporated into PE and PS lipid classes. The fatty acid composition of PI indicated specific incorporation of 20-carbon PUFA into this lipid class. Supplementation with 22:6(n-3) generated fatty acid compositions more closely resembling those of intact salmonid hearts. Substantial chain shortening of 22:6(n-3) to 20:5(n-3) occurred.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1573-5168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 4
    Electronic Resource
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    Springer
    ISSN: 1573-5168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 5
    ISSN: 1573-5168
    Keywords: rainbow trout ; dietary effects ; enzymatic adaptations ; intermediary metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Groups of trout were fed either a high protein/low carbohydrate (HP/LC) or a low protein/high carbohydrate (LP/HC) diet for 16 weeks. Fish fed the HP/LC diet had significantly higher levels of protein, ninhydrin positive material and tryptophan in plasma as well as lipid and protein in liver, but lower levels of glucose in plasma, glycogen in liver and a lower hepatosomatic index compared with fish fed the LP/HC diet. There were no differences concentrations of tryptophan or serotonin in the brain of fish fed the different diets. Fish fed the HP/LC diet had significantly lower activities of glycolytic enzymes but higher activities of gluconeogenic enzymes compared with the group fed the LP/HC diet. Those enzymes measured concerned with the TCA cycle or initiating amino acid catabolism were generally unaffected by diet although activities of threonine dehydrogenase, alanine aminotransferase and glutamate dehydrogenase were higher in those fish fed the HP/LC diet. The data suggest that rainbow trout show little adaptation in activities of amino acid catabolising enzymes to variations in dietary protein intake.
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  • 6
    ISSN: 1573-5168
    Keywords: protease activity ; protein degradation ; sex steroids ; chum salmon ; spawning migration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sarcoplasmic protein content decreased significantly and myosin heavy chain was degraded gradually during spawning migration of chum salmon (Oncorhynchus keta). Acid and neutral proteinase activities increased significantly during spawning migration. These proteinase activities were higher in females than in males. High levels of acid proteinase were not caused by the injury of lysosomal membranes. Considering the physiological states of chum salmon, neutral proteinase activity might be related to the degradation of muscle protein. As the changes in serum sex steroids were similar to those in the protease activities during spawning migration, it was considered that high levels of protease activity during spawning migration were closely related to the serum levels of androgens.
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  • 7
    ISSN: 1573-5168
    Keywords: elasmobranch ; heart ; horn shark ; pericardioperitoneal canal ; pericardium ; pressure-volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acute studies have led to the generalization that negative pericardial pressure is necessary for optimal cardiac function in elasmobranchs. We chronically instrumented horn sharks with pericardial catheters to test the hypothesis that ejection of pericardial fluid through the pericardioperitoneal canal (PPC) during routine handling could have accounted in part for previous measurements of exclusively negative pressures (−0.3 to −9.1 cm H2O) in elasmobranchs. Maximum and minimum pericardial pressures measured immediately following routine handling (acute pressures) were more negative than those measured in resting horn sharks at intervals from 1 to 27 days following handling (chronic pressures). Chronic pericardial pulse pressure was less than acute. Entirely positive pericardial pressures were observed on occasion. Handling of chronically catheterized horn sharks resulted in ejection of 21 per cent (range=10–26, n=5) of the initial pericardial fluid volume through the PPC and reduced pericardial pressure. Operating pericardial fluid volume of horn sharks averaged 2.0 ml.kg−1 (range=1.6–2.6, n=9). The PPC opened after 4.3±0.2 ml.kg−1 (x±S.E.) of elasmobranch saline had been slowly infused into the pericardium, corresponding to an average pressure of 1.3±0.2 cm H2O (n=10). The presence of the PPC plus a comparatively large pericardial fluid volume allows horn sharks to regulate pericardial pressure. Our analysis of pericardial pulse pressure, which can be an index of cardiac activity, suggests in contrast to previous studies that the elasmobranch heart can have relatively high stroke volumes at pericardial pressures near ambient. Thus, for venous return in resting or even moderately active elasmobranchs, it is more important that pericardial pressure be pulsatile than at a mean level which is negative.
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  • 8
    ISSN: 1573-5168
    Keywords: rainbow trout ; erythrocyte ; osmotic fragility ; phospholipid ; fatty acid ; diet ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rainbow trout were fed either a commercial diet or semi-purified diets containing 8% by weight of either cod liver oil, grape seed oil or hydrogenated coconut oil. Important changes in the fatty acid composition of erythrocyte membrane phospholipids were induced by these dietary fats. No changes were seen in the cholesterol/phospholipid ratio and in the cellular ATP level. Shape changes (crenation of cell margin and shrinkage) were only seen in trout fed hydrogenated coconut oil in connection with an accumulation of high amounts of (n-9) fatty acids including 20:3 (n-9) phospholipids. The compositional changes affect the stability of the erythrocyte membrane. An increased rate of osmotic hemolysis appeared to be associated with an increased unsaturated fatty acid content of the membranes.
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  • 9
    ISSN: 1573-5168
    Keywords: heat increment ; carbohydrate ; rainbow trout ; body composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was conducted to determine growth, body composition and heat increment (HI) of rainbow trout reared on isonitrogenous high digestible carbohydrate (HC) and high fat (HL) diets at 15°C. Trout reared on the HC diet had a significantly lower final body weight and carcass lipid content and a significantly higher feed:gain ratio and carcass protein content than trout reared on the HL diet after 12 weeks on the test diets. The lower carcass lipid composition indicates that trout do not readily convert dietary carbohydrates into fat. HI of trout reared on the HC diet was significantly higher than that of fish reared on the HL diet. Considering the poor utilization of dietary carbohydrates as an energy source and the apparently low conversion of dietary glucose into fat, the cause of the higher HI associated with the HC diet is not completely understood. However, it is possible the elimination of excess dietary glucose is an energy dependent process resulting in an increased heat production which would partly account for the increased HI. Furthermore, if the HC diet is a low net energy diet, then the metabolism and utilization of dietary and tissue proteins (amino acids) for energy by the trout may also be partly responsible for the increased HI of the trout reared on the HC diet.
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  • 10
    ISSN: 1573-5168
    Keywords: thiamin requirement ; thiamin status ; thiamin deficiency signs ; rainbow rout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four growth studies were conducted to determine the signs, biochemical indices and histopathology of a thiamin deficiency and the thiamin requirement of young rainbow trout reared at 15°C on a semi-purified test diet. The major overt signs of a thiamin deficiency in rainbow trout are predominantly neurological: irritability and instability. Other signs include convulsions, feed refusal, dark pigmentation and finally mortalities. Growth reduction in the thiamin deficient trout appear to result from anorexia or feed refusal and not specifically to a thiamin deficiency. Although there were prominant neurological signs in the thiamin deficient trout, there were no histopathological signs in any tissues of the trout, including the brain and central nervous system, examined by light microscopic techniques. The tissue transketolase activity would appear to be a sensitive and specific indicator of the thiamin status in the trout. In addition, the levels of plasma lactate and serum pyruvate are also elevated in thiamin deficient trout. On the basis of the growth parameters, absence of deficiency signs and kidney and liver transketolase activity, the thiamin requirement of rainbow trout reared at 15°C on a semi-purified test diet is 1 mg/kg feed.
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