Effects of lysine administration on plasma arginine and on some nitrogenous catabolites in rainbow trout

• 1.1. Rainbow trout were fed either graded levels of lysine (0.8, 1.8 and 3%) at a constant level of arginine (1.4%) or excess arginine (2.4%) at a fixed level of lysine (1.8%).
• 2.2. Increasing the dietary lysine level affected plasma urea, plasma arginine and ammonia excretion.
• 3.3. Trout fed graded levels of lysine received an arginine challenge (U¹⁴C-l-arginine) and it was found that excess dietary lysine led to a decrease in arginine degradation.
• 4.4. Injection of l-lysine induced a decrease in urea excretion, while injection of l-arginine increased both urea and ammonia excretion in control well-fed trout.
• 5.5. These results are discussed in the light of current knowledge on the antagonism between lysine and arginine.

     

Purification and characterization of elastase from the pyloric caeca of rainbow trout (Oncorhynchus mykiss)

• 1.1. An elastase-like enzyme was purified from the pyloric caeca of rainbow trout by hydrophobic interaction, cation exchange and gel-filtration chromatography.
• 2.2. The approximate molecular weight of the elastase was 27 kDa and the isoelectric point was remarkably basic.
• 3.3. The pH optimum of this enzyme was 8.0, when assayed with Succinyl-Ala-Ala-Ala-p-Nitroanilide.
• 4.4. When assayed with Succinyl-Ala-Ala-Ala-p-Nitroanilide, the enzyme activity had a temperature optimum of 45°C, and the enzyme was stable up to this temperature.
• 5.5. The trout elastase exhibited a higher specific activity than porcine elastase against Succinyl-Ala-Ala-Ala-p-Nitroanilide and elastin-orcein.
• 6.6. The trout elastase was inhibited by elastatinal, PMSF, TPCK, SBTI and Bowman-Birk inhibitor.

     

Main serum protein of rainbow trout (Salmo gairdnerii): its biological properties and significance

• 1.1. Main serum α₁-protein (α₁P) of rainbow trout was purified and its biochemical and physico-pathological properties were studied.
• 2.2. α₁P was suggested to be a primitive protein having both properties of albumin and AFP in serum proteins of mammals according to the following results.
• 3.3. Molecular weight (75,000), two kinds of molecules (pI 4.55 and 5.05) and amino acid composition.
• 4.4. Dye- or ConA binding activity.
• 5.5. Estrogen binding activity and inhibitory effect on lymphoblastoid-forming activity.
• 6.6. Possible osmotic regulator.
• 7.7. Significant elevation of blood α₁P level in the course of hepatoma induction.

     

The effect of changes in external salinity on the free amino acids and two aminotransferases of white muscle from fasted Salmo gairdneri Richardson

• 1.1. Aspartic acid. glutamic acid and serine concentrations in the white muscle of starved rainbow trout kept in diluted sea water (600 mOsm/l) for 8 days were significantly higher than in control animals kept in fresh water.
• 2.2. After 24 days the levels of all amino acids investigated (aspartic acid, glutamic acid, serine, glycine. alanine, threonine and lysine) in the white muscle of starved rainbow trout kept in diluted sea water were higher than in the white muscle of animals kept in fresh water without food.
• 3.3. Alanine aminotransferase activity in starved rainbow trout kept in diluted sea water for 24 days was higher than in the control animals kept in fresh water.
• 4.4. There is a significant correlation between alanine concentration and alanine aminotransferase activity in the white muscle of rainbow trout.

     

Properties of phosphofructokinase and tolerance to hypoxia in vertebrate myocardia

• 1.1. Kinetic properties of myocardial phosphofructokinase were compared in flounder and cod at 15°C and in an aquatic turtle and the rainbow trout at 25°C. The myocardia of flounder and turtle unlike those of the cod fish and trout maintain efficient contractility under hypoxia.
• 2.2. Flounder PFK has a lower affinity for ATP and a higher affinity for fructose-6-phosphate than cod PFK. It is less inhibited by ATP and less stimulated by AMP. For turtle PFK in relation to trout PFK the reverse is true.
• 3.3. The highest PFK activity was found between pH 7.8 and 8.0. For flounder it remained high down to pH 7.1, but was almost zero at 7.0. For cod and turtle the PFK were inactive at pH below 7.2. At pH 6.9 the activity of trout myocardial PFK was reduced about two-thirds of the maximum value.
• 4.4. Thus, no consistent differences between PFK activity of hypoxia tolerant and hypoxia non-tolerant myocardia were observed.

     

Carbohydrate metabolism in several tissues of rainbow trout,Oncorhynchus mykiss,is modified during ovarian recrudescence

• 1.1. Several pathways of carbohydrate metabolism were evaluated in three different tissues—liver, gonad and kidney—of a hatchery-reared population of rainbow trout (Oncorhynchus mykiss) which characterised two different stages of their gonadal maturation, i.e. previtellogenesis and established exogenous vitellogenesis.
• 2.2. A fall in liver glycogen levels was observed during exogenous vitellogenesis. A decrease in activity of the enzymes involved in glycolysis and in the pentose phosphate shunt was also observed, suggesting that at the end of exogenous vitellogenesis the necessity of energy and reducing power has decreased compared to the situation at the onset of this period.
• 3.3. The main changes observed in gonad during vitellogenesis were the decreased activity of glycolysis and the pentose phosphate shunt as well as increased glycogen levels. The stored glycogen should be used later in association with the embryo development.
• 4.4. No major changes were observed in kidney metabolism throughout the vitellogenic process.
• 5.5. Exogenous vitellogenesis in rainbow trout is mainly associated with increased glycogen levels in the gonad and decreased metabolic activity in the liver.

     

Potassium balance in freshwater-adapted xtrout Oncorhynchus mykiss

• 1.1. Potassium loss occurs through the gills of trout.
• 2.2. This loss is compensated by intestinal absorption.
• 3.3. During a fasting period, branchial regulation appears after 2–3 days.
• 4.4. The maintenance of potassium balance is discussed as a function of experimental conditions.

     

Electrolyte changes,cell volume regulation and hormonal influences during acclimation of rainbow trout (Salmo gairdnerii) to salt water

• 1.1. Rainbow trout were acclimated to salt water (1.5, 2.0 or 3.0%, which means 40, 60 or 85% concentrated sea-water) and the electrolyte, glucose and cortisol concentrations of the plasma as well as the extra- and intracellular muscle space, the muscle electrolyte concentrations and the ATPase activity were analysed.
• 2.2. Plasma osmolality, Na⁺, Ca²⁺ and Mg²⁺ concentrations of the plasma had a maximum at 24 hr after the start of acclimation when acclimated to 3.0% salt water. Plasma osmolality, Na⁺ and Mg²⁺ concentrations were significantly higher during the whole acclimation time when exposed to 3.0% salt water.
• 3.3. Variations and regulations of ECS and ICS were clearly demonstrated. The intracellular electrolyte concentrations were also maximal at 24 hr.
• 4.4. The plasma glucose level was just slightly elevated, but the cortisol level clearly indicated a stress response at 24 hr.
• 5.5. The activity of gill Na-K-ATPase increased during the acclimation time.
• 6.6. The regulatory processes in trout during acclimation to salt water are compared with those occurring in tilapia and carp.

     

The effect of water loss upon the urate,urea and ammonia content of the egg of the Japanese quail Coturnix coturnix japonica

• 1.1. The urate, urea and ammonia content of the whole egg of the Japanese quail was measured in late incubation in eggs subject to different rates of water loss.
• 2.2. High rates of water loss substantially increased egg urate content, but had little or no effect on urea or ammonia content.
• 3.3. Allopurinol, an inhibitor of urate synthesis, reduced egg urate content to low levels, but produced no effect on urea content, and a small reduction in ammonia content.
• 4.4. The urea concentration of the embryo was lower than in allantoic fluid.
• 5.5. It is concluded that urate production by the avian embryo is primarily concerned with the modification of allantoic fluid composition.

     

The effect of temperature on oxygen equilibrium curves of trout blood (Salmo gairdnerii)

• 1.1. Oxygen equilibrium curves were measured on trout red blood cell suspensions at pH 7.8 and 8.4 at 15, 20 and 25 C. Normal red cells and red cells that had been depleted of their ATP content were used.
• 2.2. The equilibrium data were fitted to the Adair's model and the enthalpy (ΔH) and entropy (ΔS) changes for the first and fourth steps of oxygenation and for overall oxygenation were calculated from the temperature dependencies of the Adair constants.
• 3.3. For normal red blood cells, the apparent heat for the first oxygenation step, δh₁, is close to zero.
• 4.4. Temperature insensitivity of this step at physiological pH, combined with a large pH dependence, probably denotes a property of Hb4, the Root effect Hb of trout blood.
• 5.5. At pH 7.8, ΔH₄ is about —4kcal/mol, a small value which may be attributed to the large release of Bohr protons that occurs at the last oxygenation step and corresponds to an endothermic process which opposes to the exothermic oxygenation of the haem.
• 6.6. The ΔH₄ value appears to have a large influence on the enthalpy for overall oxygenation.
• 7.7. Results for ATP-free red cells are consistent with a mere increase in the intracellular pH and suggest that ATP has no specific effect at and above pH_i ~ 7.7.
• 8.8. Effects of temperature and pH on trout red blood cell isotherms emphasize the primary importance of the major component of trout blood, namely Hb4, in trout blood functional properties.

     

The peculiarities of nitrogen excretion in sturgeons (Acipenser ruthenus) (Pisces,Acipenseridae)—I. the influence of ration size

• 1.1. The nonfaecal nitrogenous excretion rate in starved sterlet fingerlings and fingerlings fed on different rations was investigated. The weight of the fish and temperature of the water was 43 g and 17.5°C, respectively.
• 2.2. In the nonfaecal excrements of starved sterlets the ammonia: urea ratio was substantially lower than in teleosts. This ratio was found to be 1.4:1.
• 3.3. In fed sterlets the urea excretion rate was higher than in starved ones but independent of ration size.
• 4.4. During the day the urea excretion rate in sterlets was constant.
• 5.5. The ammonia excretion rate accelerated 2 hr after feeding and reached its peak duration 6–11 hr after depending on the ration size.
• 6.6. Total ammonia output in the sterlet increased following the increase of ration size up to 8.4% of body wt. Further increases in ration size did not cause the corresponding elevation of ammonia excretion rate.

     

Xenobiotic metabolizing enzymes in rainbow trout exposed to river water

• 1.1. Juvenile rainbow trout were exposed to river water in a flow-through system. After 15 days of exposure, hepatic biotransformation activities and related parameters were measured and compared to those of the control group organisms that were maintained in tap water under identical experimental conditions.
• 2.2. Liver somatic index (LSI), microsomal protein and cytochrome P-450 contents, benzo[a]pyrene hydroxylase (AHH), ethoxyresorufin-O-deethylase (EROD) and UDP glucuronyl transferase activities were not significantly affected.
• 3.3. Aminopyrine-N-demethylase (APD) activity showed a slight yet significant increase in exposed trout.

     

Nucleoside monophosphoramidate hydrolase from rat liver: Purification and characterization

• 1.1. Adenosine 5'-phosphoramidate hydrolase of 29 kDa was isolated from rat liver cytosol.
• 2.2. It consisted of two subunits of 14 kDa.
• 3.3. It hydrolyzed nucleoside 5'-monophosphoramidates into nucleoside 5'-monophosphates and ammonia, while it did not hydrolyze adenylyl phosphoramidate, adenylyl imidodiphosphate and N-phosphorylated compounds like phosphocreatine, N^ω-phosphoarginine, 6-phospholysine and 3-phosphohistidine.
• 4.4. Divalent cations and cyclic AMP had no effect on the hydrolytic activity.

     

Demonstration of specific receptors for calcitonin in isolated trout gill cells

• 1.1. Salmon calcitonin binding by isolated gill cells from rainbow trout, Salmo gairdneri has been investigated.
• 2.2. The calcitonin receptor interaction is time- and temperature-dependent.
• 3.3. 50% of inhibition of the ¹²⁵I labeled calcitonin binding is observed in presence of 1.5 ng/ml unlabeled salmon calcitonin.
• 4.4. Two types of receptors are described: a high affinity-low capacity site and a low affinity-large capacity site.
• 5.5. These studies strongly support the role of calcitonin as a hormone regulating the gill function in physiological conditions.

     

Regulation of glutamine catabolism in the perfused guinea-pig liver in relation to ureogenesis and gluconeogenesis

• 1.1. L-Glutamine conversion into ammonia, urea and glucose by the perfused liver of 48 hr starved guinea-pigs was concentration dependent attaining the maximal rate at 4 mM.
• 2.2. The activity of glutaminase I (EC 3.5.12), measured in isolated liver mitochondria was high enough to account for the observed rate of ammonia, urea and glucose formation by the perfused liver. Neither NH4C1 (5 mM) nor aminooxyacetate (0.5 mM) affected the rate of glutamine conversion into glutamate by isolated liver mitochondria.
• 3.3. Gluconeogenesis and ureogenesis from glutamine was inhibited by octanoate, Dt-3-hydroxybutyrate, aminooxyacetate, ethanol and p-hydroxyphenylpyruvate while ammonia formation was stimulated by aminooxyacetate. 2,4-Dinitrophenol stimulated the rate of the formation of all three metabolites from glutamine.
• 4.4. The major changes induced by aminooxyacetate, as determined in livers perfused with glutamine and stopped by freeze-clamping technique, consisted in a decrease in the content of ATP, aspartate and malate and in a slight increase in the content of glutamate.
• 5.5. Glutamine is an effective precursor of phosphoenolpyruvate in isolated liver mitochondria. Its formation was inhibited by octanoate and by DL-3-hydroxybutyrate.
• 6.6. The data are discussed in terms of regulation of glutamine catabolism in liver with emphasis on ureogenesis and gluconeogenesis.

     

Effects of aluminium and pH on calcium fluxes,and effects of cadmium and manganese on calcium and sodium fluxes in brown trout (Salmo trutta L.)

• 1.1. Simultaneous measurement of calcium fluxes in brown trout, at low external [Ca] (20 μ mol 1⁻¹), provided evidence of active uptake of Ca from the medium.
• 2.2. At pH 4.5, calcium influx was inhibited and efflux was stimulated.
• 3.3. Cd and Mn, but not Al, at concentrations within the ranges found in acid waters experiencing fish population decline, inhibited calcium influx. Efflux was unaffected.
• 4.4. Cd and Mn stimulated sodium influx and efflux.

     

Plasma metabolites of lake trout (Salvelinus namaycush) in relation to diet and storage conditions

• 1.1. The effects of storage temperature (2, −20 and −80°C) and duration (3, 9 and 27 days) on plasma metabolites concentrations of lake trout fed three dietary protein levels (20, 40 and 60%) and a single lipid level (20%) for 28 days were investigated.
• 2.2. Significantly high plasma urea and glucose concentrations were associated with low (20%) and high (60%) dietary protein intake in fish; while, high plasma creatinine concentration seems to characterize insufficient dietary protein and energy consumption.
• 3.3. Deproteinization of plasma with 5.0% sulfosalicylic acid did not confer better storage stability for any of the plasma metabolites except ammonia which was significantly high in non-deproteinized samples when stored at 2°C over 3, 9 and 27 day periods.
• 4.4. These studies suggest that non-deproteinized fish plasma can be stored at − 20°C without affecting the baseline concentrations of ammonia, creatinine and glucose for up to 9 days and, urea and total protein for up to 27 days.

     

Influence of temperature,rate of feeding and body weight on nitrogen metabolism of bream,Abramis brama L

• 1.1. Measurements of the rate of nitrogen consumption, total nitrogen and ammonia excretion and nitrogen absorption of bream, Abramis brama L. (body weight range 0.4–519 g wet wt) were made at 10, 15 and 20 C.
• 2.2. Fish were fed once daily on live zooplankton collected in Lake Balaton and cultured Tubifex sp. at 5–15% of their body weight.
• 3.3. Fish size and temperature had a combined effect on the rate of total nitrogen excretion. Total nitrogen excretion did not increase proportionally with an increase in consumption.
• 4.4. On average, 52–80% of the nitrogen consumed with food was excreted by bream.
• 5.5. The greatest part of total nitrogen excretion was ammonia and its proportion in the total ranged between 53 and 75%.
• 6.6. Temperature did not have any significant effect on the proportion of excreted ammonia and the rate of excreted total nitrogen was the only factor determining its proportion in the total.
• 7.7. The rate of nitrogen absorption of bream was surprisingly very high.

     

Influence of handling and/or anaesthesia on stress response in rainbow trout. Effects on liver primary metabolism

• 1.1. The overall effect of handling, anaesthesia and sham injection on some blood metabolites, liver glycogen and several key enzymes involved in liver carbohydrates and nitrogen metabolism was studied in rainbow trout. In addition, the possible role of anaesthesia (MS222) itself as a stress-inductor or suppressor was also studied.
• 2.2. Stress resulted in hyperglycaemia and initially in liver glycogen depletion, as well as increasing plasma amino acid levels.
• 3.3. Glycogen stores subsequently recovered while amino acid concentration fell.
• 4.4. These changes seemed to correlate with the increased activity of liver fructose 1,6-bisphosphatase, glucose 6-phosphate dehydrogenase, alanine aminotransferase and glutamate dehydrogenase, thus supporting the hypothesis that gluconeogenic flux from amino acids increases in stressed trouts.
• 5.5. Anaesthesia, under the same experimental conditions, did not seem to mediate in stress production, but rather resulted in stress suppression.

     

The activity of glutathione S-transferase in hepatopancreas of Procambarus clarkii: Seasonal variations and the influence of environmental pollutants

• 1.1The glutathione S-transferase activity in hepatopancreas of the American red crayfish Procambarus clarkii after 15 days' acclimatization in tap water aquaria was measured in specimens collected monthly for a whole year, and shows seasonal variation.
• 2.2. Previous data on the environmental pollution of Lake Albufera suggest a possible correlation with the activity tested in the different seasons of the year considering the results of non-acclimatized animals.