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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture nutrition 3 (1997), S. 0 
    ISSN: 1365-2095
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: This study was undertaken to determine acceptable dietary concentrations of high-fibre canola meal (CMHF) and low-fibre canola meal (CMLF) for juvenile shrimp, Penaeus vannamei. Four groups of 0.78 g shrimp held in running, 24.0–27.8°C sea water on a 12 h light: 12 h dark cycle were each fed one of seven isonitrogenous (340 g kg−1 protein) and isoenergetic (18.5 MJ of gross energy kg−1) diets to satiation four times daily for 56 days. Each of the test canola protein products comprised either 150, 300 or 450 g kg−1 of the protein in a basal (practical) diet by replacement of one-third, two-thirds or all of the menhaden meal protein.Shrimp that ingested diets in which CMHF and CMLF comprised 450 and 300 g kg−1 of the protein, respectively, exhibited significant reductions in growth and feed intake relative to those fed the basal diet. Feed and protein utilization were not significantly depressed unless menhaden meal in the basal diet was completely replaced by CMHF or CMLF. In general, percentage survival and final whole-body levels of protein, minerals, and thyroid hormones were not significantly affected by dietary treatment. Terminal whole-body levels of moisture were raised significantly in shrimp fed diets containing the highest levels of CMHF and CMLF. Potassium levels were significantly higher in shrimp fed the diet containing the lowest level of CMLF relative to those fed the basal diet and the diet with the highest level of CMLF. Water stability of the diet pellets was negatively correlated with their levels of CMHF and CMLF.It is concluded that commercial high-fibre canola meal can constitute 300 g kg−1 of the dietary protein of juvenile shrimp (Penaeus vannamei) without compromising growth, feed intake and feed and protein utilization. However, because of a trend towards reduced shrimp survival at this dietary concentration of canola meal, it is recommended that this protein source not exceed 150 g kg−1 of the protein in practical juvenile shrimp diets. Fibre-reduced canola meal did not have improved nutritive value for shrimp. However, we postulate that one or more fibre-reduced, and solvent-extracted canola protein products may be cost-effective substitutes for fish meal protein.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 36 (1990), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The effects of 17β-oestradiol (E2) on plasma kinetics of thyroid hormones (T4, l-thyroxine; T3, 3,5,3′-triiodo-l-thyronine) were studied in immature rainbow trout. E2-3-benzoate (0.5 mg/100 g) was injected intraperitoneally on days 0 and 3, and on the morning of day 4 each trout received an intracardiac injection of either [125I]T4 and Na 131I or [I25I]T3. Groups of trout were bled and killed from 5 min to 4 days post-injection of tracer. E2 did not alter the plasma T4 level but depressed the T4 plasma clearance rate, plasma-to-total tissue flux of T4 and thyroidal T4 secretion rate. Monodeiodination of T4 to T3 was also depressed, as judged from plasma [I25I]T3 and I25I − levels in [125I]T4-injected trout. E2 had no major effect on T3 plasma clearance rate but depressed the plasma T3 level, plasma-to-total tissue flux of T3 and the T3 plasma appearance rate. E2 had no influence on biliary transport of [I25I]T4 or [125I]T3. The above results suggest that E2, at the dose range employed, depresses extrathyroidal T4 to T3 conversion, which may in turn decrease plasma T4 clearance and thyroidal T4 secretion.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Reviews in fish biology and fisheries 6 (1996), S. 165-200 
    ISSN: 1573-5184
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Fish physiology and biochemistry 3 (1987), S. 127-131 
    ISSN: 1573-5168
    Keywords: thyroid ; T4 ; T3 ; tropical marine teleosts ; free T4 ; free T3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plasma levels of L-thyroxine (T4) and 3,5,3′-triiodo-L-thyronine (T3) and the percentage of plasma T4 and T3 present in the free (dialyzable) form (%FT4 and %FT3) were measured in 16 species (11 families) of tropical marine teleosts from an inshore Barbados reef. Mean plasma T4 varied from 0.2 ng/ml to 42 ng/ml; mean plasma T3 varied from 〈 0.2 ng/ml to 50 ng/ml. The highest T4 and T3 levels were recorded in parrot-fish and the lowest levels in filefish. The %oFT4 and %FT3 varied from 0.05–3.41%. Estimated levels of plasma free T4 and free T3 levels ranged from 0.4–466 pg/ml. The extremely wide inter- and intra-species ranges in levels of free T4 and T3 do not support a previous suggestion, based on temperate freshwater salmonid species, that free T4 and T3 levels in fish may fall within a relatively range narrow comparable to that of homeothermic vertebrates.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5168
    Keywords: alkaline phosphatase isoenzymes ; thyroxine ; triiodothyronine ; smoltification ; gonadal development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in tissue and plasma isoenzymes of alkaline phosphatase (ALP) were qualitatively and quantitatively determined for male and female Atlantic salmon parr, silvery parr, smolt, immature grilse, prespawning grilse and postspawning grilse using cellulose acetate electrophoresis, densitometry and spectrophotometry. Tissue ALP isoenzymes were isolated from intestine, kidney, bone, liver, and gonad and compared to plasma isoenzymes. Parr plasma displayed three isoenzymes from bone and liver (slow and fast). During smoltification, ALP activity increased in tissue extracts from liver, gonad, and kidney of males and females. Total plasma ALP activity also increased and was due to slow and fast liver isoenzymes. During ovarian development, total ALP plasma activity increased in females and was due mostly to liver isoenzymes and an incompletely identified isoenzyme or isoenzyme mixture (band 2). However, in males total ALP plasma activity did not increase during maturation and no band 2 was evident. In male and female maturing adult grilse, bone ALP activity declined and the isoenzyme band evident in parr plasma could not be detected. ALP activity declined in the plasma of postspawning males and females. In females this was due partly to the total clearance of band 2 from the plasma, together with lowered levels of liver isoenzymes. Treatment of postspawned grilse in February and March with triiodothyronine and thyroxine elevated plasma thyroid hormone levels and increased plasma ALP levels. In conclusion, plasma ALP isoenzyme activities change with physiological state, and knowledge of the conditions governing these changes is important when using these enzymes as a diagnostic tool.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5168
    Keywords: thyroxine ; triiodothyronine ; enterohepatic cycle ; intestinal uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The absorptions of 3,5,3′-triiodo-L-thyronine (T3) and L-thyroxine (T4) from the intestinal lumen of the rainbow trout were compared in vivo. Tracer doses of [125I]T4 (+T4) or [125I]T3 (*T3) were injected through an anal cannula into the duodenum of trout fasted for 3 days at 12°C, and radioactivity was measured in blood and tissues at 4–48 h. *T3 was removed more extensively than *T4 from the intestinal lumen and more radioactivity was absorbed into the blood and tissues of u+T3-injected trout than *T4-injected trout. HPLC analysis showed that a high proportion of the radioactivity in the plasma, liver, kidney and intestinal lumen of *T3-injected trout remained as the parent *T3. However, in *T4-injected trout most plasma radioactivity was in the form of 125I−, and by 24 h a high proportion of luminal radioactivity was 125I−. By 48 h, over 4% of the injected *T3 and 1% of the injected *T4 dose resided in the gall bladder, primarily as derivatives of *T3 or *T4. We conclude that T3 is absorbed more effectively than T4 from the intestinal lumen of fasted trout, indicating the potential for an enterohepatic T3 cycle.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5168
    Keywords: triiodothyronine ; trout ; low pH ; Al ; tissue T3 extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tissue T3 (3,5,3′-triiodo-L-thyronine) concentrations were measured in rainbow trout, Salmo gairdneri, after digestion by Pronase or collagenase and extraction with ethanolic ammonia (99:1, v/v) followed by 2N NH4OH and chloroform. Recoveries of [125I]T3 administered in vivo or in vitro were high and consistent and there was close parallelism between sample dilutions and the radioimmunoassay curve, but recoveries of unlabeled T3 administered in vitro were low and variable. Alternatively, trout were brought to isotopic equilibrium by [125I]T3 infusion for 96 h, the extracted [125I]T3 determined by gel filtration and the tissue T3 content calculated from the specific activity of plasma [125I]T3. By the latter method, tissue T3 concentrations were: intestine (4.2 ng/g), kidney (2.5), liver (2.8), stomach (1.5), heart (1.0), muscle (0.7), gill (0.6) and skin (0.3). Muscle (67% of body weight) comprised the largest tissue T3 pool (82% of all tissues examined). Seven days exposure of trout to water acidified with H2SO4 (pH 4.8) or acidified water containing aluminum (21.6 mM), decreased tissue T3 content generally and particularly in muscle (14% of controls). In conclusion, skeletal muscle is the largest T3 tissue pool and seems highly responsive to altered physiologic state.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Fish physiology and biochemistry 6 (1989), S. 255-259 
    ISSN: 1573-5168
    Keywords: T3 ; estradiol-17β ; ovary ; trout ; gonadotropin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cellular mechanism of action of 3,5,3′-triiodo-L-thyronine (T3) in enhancing SG-G100 gonadotropin-induced ovarian secretion of 17β-estradiol (E2) was studiedin vitro using oocyte follicular preparations of rainbow trout. The dependence of the T3 stimulatory action on the level of intracellular 3′,5′-cyclic adenosine monophosphate (cAMP) was shown in experiments in which forskolin or dibutyryl cAMP enhanced E2 secretion. In the presence of partially purified salmon gonadotropin (SG-G100), T3 stimulation of E2 secretion was prevented by theophylline, suggesting that T3 may exert part of its stimulatory action by inhibiting phosphodiesterase.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Fish physiology and biochemistry 7 (1989), S. 289-293 
    ISSN: 1573-5168
    Keywords: thyroid ; deiodinase ; T4 ; T3 ; rainbow trout ; energy balance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extrathyroidal T4 5′-monodeiodination, demonstrated in several teleost species, generates T3 which binds more effectively than T4 to putative nuclear receptors and is probably the active thyroid hormone. T4 to T3 conversion is sensitive to the physiological state and provides a pivotal regulatory link between the environment and thyroid hormone action. T3 generation is enhanced in anabolic states (positive energy balance or conditions favoring somatic growth; food intake or treatment with androgens or growth hormone) and is suppressed in catabolic states (negative energy balance or conditions not favoring somatic growth; starvation, stress, or high estradiol levels associated with vitellogenesis). In fish, as in mammals, thyroidal status may be finely tuned to energy balance and through T3 production regulate energy-demanding processes, which in fish include somatic growth, development and early gonadal maturation.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fish physiology and biochemistry 1 (1986), S. 171-177 
    ISSN: 1573-5168
    Keywords: thyroid ; excess iodide ; T4 ; T3 ; rainbow trout ; Salmo gairdneri ; radioiodide kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The acute and chronic effects of excess iodide (KI or NaI) were studied on thyroid function of rainbow trout at 11±1°C. No Wolff-Chaikoff effect, characteristic of mammals, was observed and instead plasma L-thyroxine (T4) levels increased 6 hr after a single iodide injection. Plasma 3,5,3′-triiodo-L-thyronine (T3) did not change and by 24 hr plasma T4 returned to normal. This iodide-induced elevation in plasma T4 was probably not due to toxic effects demonstrated at higher NaI or KI doses. A single iodide injection also decreased the plasma iodide distribution space, decreased the fractional rate of plasma iodide loss and completely blocked thyroidal uptake of radioiodide. Injections of iodide over a 22-day period elevated plasma iodide 200X with no mortality and no influence on plasma T4 or T3. It is concluded that: (i) apart from the transient 6h increase in plasma T4, trout thyroid function, as judged by plasma hormone levels, is insensitive to considerable iodide excess, (ii) non-invasive iodide suppression of thyroidal radioiodide recycling may be useful in kinetic studies of125I-labeled thyroid hormones, and (iii) fundamental differences in intrathyroidal iodine metabolism appear to exist between mammals and fish.
    Type of Medium: Electronic Resource
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