Increasing levels of dietary crystalline methionine affect plasma methionine profiles, ammonia excretion, and the expression of genes related to the hepatic intermediary metabolism in rainbow trout (Oncorhynchus mykiss)

2016 ◽  
Vol 198 ◽  
pp. 91-99 ◽  
Author(s):  
Marine Rolland ◽  
Peter V. Skov ◽  
Bodil K. Larsen ◽  
Jørgen Holm ◽  
Pedro Gómez-Requeni ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Ammonia Excretion ◽  
Intermediary Metabolism ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Expression Of Genes

scholarly journals Apparent low ability of liver and muscle to adapt to variation of dietary carbohydrate:protein ratio in rainbow trout (Oncorhynchus mykiss)

2012 ◽  
Vol 109 (8) ◽  
pp. 1359-1372 ◽  
Author(s):  
Sandrine Skiba-Cassy ◽  
Stéphane Panserat ◽  
Mélanie Larquier ◽  
Karine Dias ◽  
Anne Surget ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Amino Acid ◽  
Oncorhynchus Mykiss ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Futile Cycle ◽  
High Carbohydrate ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Low Protein ◽  
Expression Of Genes

The rainbow trout (Oncorhynchus mykiss) exhibits high dietary amino acid requirements and an apparent inefficiency to use dietary carbohydrates. Using this species, we investigated the metabolic consequences of long-term high carbohydrates/low protein feeding. Fish were fed two experimental diets containing either 20 % carbohydrates/50 % proteins (C20P50), or high levels of carbohydrates at the expense of proteins (35 % carbohydrates/35 % proteins – C35P35). The expression of genes related to hepatic and muscle glycolysis (glucokinase (GK), pyruvate kinase and hexokinase) illustrates the poor utilisation of carbohydrates irrespective of their dietary levels. The increased postprandial GK activity and the absence of inhibition of the gluconeogenic enzyme glucose-6-phosphatase activity support the hypothesis of the existence of a futile cycle around glucose phosphorylation extending postprandial hyperglycaemia. After 9 weeks of feeding, the C35P35-fed trout displayed lower body weight and feed efficiency and reduced protein and fat gains than those fed C20P50. The reduced activation of eukaryotic translation initiation factor 4-E binding protein 1 (4E-BP1) in the muscle in this C35P35 group suggests a reduction in protein synthesis, possibly contributing to the reduction in N gain. An increase in the dietary carbohydrate:protein ratio decreased the expression of genes involved in amino acid catabolism (serine dehydratase and branched-chain α-keto acid dehydrogenase E1α and E1β), and increased that of carnitine palmitoyltransferase 1, suggesting a higher reliance on lipids as energy source in fish fed high-carbohydrate and low-protein diets. This probably also contributes to the lower fat gain. Together, these results show that different metabolic pathways are affected by a high-carbohydrate/low-protein diet in rainbow trout.

Excretion and distribution of ammonia and the influence of boundary layer acidification in embryonic rainbow trout (Oncorhynchus mykiss)

1996 ◽  
Vol 199 (12) ◽  
pp. 2713-2723 ◽  
Author(s):  
E Rahaman-Noronha ◽  
M Donnell ◽  
C Pilley ◽  
P Wright
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Electrical Potential ◽  
Ammonia Excretion ◽  
Free Water ◽  
Bulk Water ◽  
Water Addition ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
External Water ◽  
Excretion Rates

This study examined ammonia excretion by embryos of the rainbow trout (Oncorhynchus mykiss). The distribution of ammonia in relation to the H+ distribution and electrical potential was determined. The influence of the pH of the unstirred layer (USL) of water next to the external surface of the embryo was also assessed. Eyed-up embryos (35­40 days post-fertilization) were exposed to various external water conditions [pH 6.0, pH 10.0, 1.6 mmol l-1 NaCl, 0.0 mmol l-1 NaCl, 0.2 mmol l-1 NH4Cl, 2.5 mmol l-1 borax buffer (Na2B4O7.10H2O), 2.5 mmol l-1 Hepes, 0.1 mmol l-1 amiloride] for 30 min and ammonia excretion rates, ammonia concentration in the perivitelline fluid (PVF) and yolk, and the pH of the PVF, yolk and USL were measured. The rate of ammonia excretion was dependent, in part, on the partial pressure gradient of NH3 ( PNH3) from the PVF to the USL. Exposure to water of pH 6 increased, whereas NH4Cl or pH 10 exposure decreased, ammonia excretion rates. Elevated external Na+ levels also influenced the rate of ammonia excretion, but neither Na+-free water nor amiloride had any effect. The distribution of ammonia between the PVF and USL was dependent on the H+ distribution, but ammonia was distributed according to the electrical potential between the PVF and yolk. The USL was 0.32 pH units more acidic than the bulk water. Addition of buffer to the external water eliminated the acid USL and decreased ammonia excretion rates. We conclude that rainbow trout embryos excrete ammonia primarily as NH3, but when external Na+ levels are elevated, ammonia excretion may be independent of the PNH3 gradient. The acidic USL next to the chorion probably facilitates NH3 diffusion by maintaining the PNH3 through the conversion of NH3 to NH4+ upon entry into the USL.

A respirometric analysis of fuel use during aerobic swimming at different temperatures in rainbow trout (Oncorhynchus mykiss)

1998 ◽  
Vol 201 (22) ◽  
pp. 3123-3133 ◽  
Author(s):  
JD Kieffer ◽  
D Alsop ◽  
CM Wood
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Swimming Speed ◽  
Ammonia Excretion ◽  
Whole Body ◽  
Acclimation Temperature ◽  
Fish Swimming ◽  
Fuel Use ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Absolute Basis

Instantaneous fuel usage at 5 degreesC or 15 degreesC was assessed by measurement of rates of O2 consumption (O2), CO2 excretion (CO2) and nitrogenous waste excretion (nitrogen =ammonia-N + urea-N) in juvenile rainbow trout (Oncorhynchus mykiss) at rest and during swimming at 45 % and 75 % of aerobic capacity (Ucrit). After 2 weeks of training at approximately 1 body length s-1 (BL s-1), critical swimming speeds (approximately 3.0 BL s-1) and whole-body energy stores (total protein, lipids and carbohydrates) were identical in fish acclimated to 5 degreesC or 15 degreesC. O2 and CO2 increased with swimming speed at both temperatures and were higher at 15 degreesC than at 5 degreesC at all speeds, but the overall Q10 values (1.23-1.48) were low in these long-term (6 weeks) acclimated fish. The respiratory quotient (CO2/O2, approximately 0.85) was independent of both temperature and swimming speed. In contrast to O2 and CO2, the rate of ammonia excretion was independent of swimming speed, but more strongly influenced by temperature (Q10 1. 4-2.8). Urea excretion accounted for 15-20 % of nitrogen, was unaffected by swimming speed and showed a tendency (P<0.07) to be positively influenced by temperature at one speed only (45 % Ucrit). Nitrogen quotients (NQ nitrogen/O2) were generally higher in warm-acclimated fish, remaining independent of swimming speed at 15 degreesC (0.08), but decreased from about 0.08 at rest to 0.04 during swimming at 5 degreesC. Instantaneous aerobic fuel use calculations based on standard respirometric theory showed that both acclimation temperature and swimming speed markedly influenced the relative and absolute use of carbohydrates, lipids and proteins by trout. At rest, cold-acclimated trout used similar proportions of carbohydrates and lipids and only 27 % protein. During swimming, protein use decreased to 15 % at both speeds while the relative contributions of both lipid and carbohydrate increased (to more than 40 %). On an absolute basis, carbohydrate was the most important fuel for fish swimming at 5 degreesC. In contrast, resting fish acclimated to 15 degreesC utilized 55 % lipid, 30 % protein and only 15 % carbohydrate. However, as swimming speed increased, the relative contribution of carbohydrate increased to 25 %, while the protein contribution remained unchanged at approximately 30 %, and lipid use decreased slightly (to 45 %). On an absolute basis, lipid remained the most important fuel in fish swimming at 15 degreesC. These results support the concept that lipids are a major fuel of aerobic exercise in fish, but demonstrate that the contribution of protein oxidation is much smaller than commonly believed, while that of carbohydrate oxidation is much larger, especially at higher swimming speeds and colder temperature.

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