Free Arginine Levels Research Articles

Arginine, ornithine and citrulline supplementation in rainbow trout: Free amino acid dynamics and gene expression responses to bacterial infection

Supplementing the diet with functional ingredients is a key strategy to improve fish performance and health in aquaculture. The amino acids of the urea and nitric oxide (NO) cycles - arginine, ornithine and citrulline - perform crucial roles in the immune response through the generation of NO and the synthesis of polyamine used for tissue repair. We previously found that citrulline supplementation improves and maintains circulating free arginine levels in rainbow trout more effectively than arginine supplementation. Here, to test whether supplementation of urea cycle amino acids modulates the immune response in rainbow trout (Oncorhynchus mykiss), we supplemented a commercial diet with high levels (2% of total diet) of either arginine, ornithine or citrulline during a 7-week feeding trial, before challenging fish with the bacterium Aeromonas salmonicida. We carried out two separate experiments to investigate fish survival and 24 h post-infection to investigate the immediate response of free amino acid levels, and transcriptional changes in genes encoding urea cycle, NO cycle and polyamine synthesis enzymes. There were no differences in percentage fish mortality between diets, however there were numerous highly significant changes in free amino acid levels and gene expression to both dietary supplementation and infection. Out of 26 amino acids detected in blood plasma, 8 were significantly changed by infection and 9 by dietary supplementation of either arginine, ornithine or citrulline. Taurine, glycine and aspartic acid displayed the largest decreases in circulating levels in infected fish, while ornithine and isoleucine were the only amino acids that increased in concentration. We investigated transcriptional responses of the enzymes involved in arginine metabolism in liver and head kidney; transcripts for polyamine synthesis enzymes showed highly significant increases in both tissues across all diets following infection. The paralogous arginase-encoding genes, Arg1a, Arg1b, Arg2a and Arg2b, displayed complex responses across tissues and also due to diet and infection. Overall, these findings improve our understanding of amino acid metabolism following infection and suggests new potential amino acid targets for improving the immune response in salmonids.

Arginine methylation dysfunction increased risk of acute coronary syndrome in coronary artery disease population: A case-control study.

The plasma levels of asymmetric dimethylarginine (ADMA) had been proved to be an independent cardiovascular risk factor. Few studies involved the entire arginine methylation dysfunction. This study was designed to investigate whether arginine methylation dysfunction is associated with acute coronary syndrome risk in coronary artery disease population.In total 298 patients undergoing coronary angiography because of chest pain with the diagnosis of stable angina pectoris or acute coronary syndrome from February 2013 to June 2014 were included. Plasma levels of free arginine, citrulline, ornithine, and the methylated form of arginine, ADMA, and symmetric dimethylarginine (SDMA) were measured with high-performance liquid chromatography coupled with tandem mass spectrometry. We examined the relationship between arginine metabolism-related amino acids or arginine methylation index (AMI, defined as ratio of [arginine + citrulline + ornithine]/[ADMA + SDMA]) and acute coronary events.We found that plasma ADMA levels were similar in the stable angina pectoris group and the acute coronary syndrome group (P = 0.88); the AMI differed significantly between 2 groups (P < 0.001). Multivariate logistic regression demonstrated that AMI was an independent risk factor of acute coronary events in patients with coronary artery disease (OR = 0.975, 95% confidence interval 0.956–0.993; P = 0.008).Our study suggested that ADMA levels were very similar in the stable angina and acute coronary syndrome patients; AMI might be an independent risk factor of acute coronary events in coronary artery disease population.

The effect of high temperature interruptions during inductive period on the extent of flowering and on metabolic responses in olives ( Olea europaea L.)

The effect of the duration of high temperature interruption and the timing of its occurrence during inductive period on the extent of inhibition of inflorescence production in ‘Arbequina’ olive trees was investigated. Trees kept under inductive conditions in different growth chambers were subjected to high daytime temperature (26 ± 1 °C) interruptions for 3, 6, and 12 days. There was no significant difference in the extent of flowering between trees given an uninterrupted induction period and the trees where inductive period was interrupted with high daytime temperatures for three days. Inflorescence production was significantly reduced by both 6 and 12 days high temperature interruptions. Number of flowers per inflorescence was significantly reduced only with 12 days high temperature interruption. Since there was no significant difference between the extent of inhibition of inflorescence by 6 and 12 days high temperature interruption, therefore, 6 days high temperature interruption was used in subsequent experiments to study the effect of timing of interruption. A six day interruption of high temperature produced significant reduction (more than 83%) in inflorescence production irrespective of the time of interruption (i.e., 40 or 50 days after the start of induction) or number of interruptions. None of these treatments had any significant effect on the number of flowers per inflorescence. Higher levels of free arginine were found in trees that had greatest number of inflorescences produced under inductive conditions without any high temperature interruption.

Diminished Global Arginine Bioavailability and Increased Arginine Catabolism as Metabolic Profile of Increased Cardiovascular Risk

We hypothesized that an integrated assessment of arginine with its catabolic products might better predict cardiovascular risks than arginine levels alone. Arginine is the sole nitrogen source for nitric oxide (NO) synthesis. The major catabolic products of arginine are ornithine and citrulline. Plasma levels of free arginine, ornithine, citrulline, and the endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) were measured with liquid chromatography coupled with tandem mass spectrometry. We examined the relationship of global arginine bioavailability ratio (GABR) (defined as arginine/[ornithine + citrulline]) versus arginine and its catabolic metabolites to prevalence of significantly obstructive coronary artery disease (CAD) and incidence of major adverse cardiovascular events (MACE) (death, myocardial infarction, stroke) over a 3-year follow-up in 1,010 subjects undergoing elective cardiac catheterization. Patients with significantly obstructive CAD had significantly lower GABR (median [interquartile range]: 1.06 [0.75 to 1.31] vs. 1.27 [0.96 to 1.73], p < 0.001) and arginine levels [mean: 68 +/- 20 micromol/l vs. 74 +/- 24 micromol/l, p < 0.001) than those without significantly obstructive CAD. After adjusting for Framingham risk score, C-reactive protein, and renal function, lower GABR (but not arginine levels) and higher citrulline levels remained significantly associated with both the prevalence of significantly obstructive CAD (adjusted odds ratio: 3.93, p < 0.001, and 5.98, p < 0.001, respectively) and 3-year risk for the incidence of MACE (adjusted hazard ratio: 1.98, p = 0.025, and 2.40, p = 0.01, respectively) and remained significant after adjusting for ADMA. GABR might serve as a more comprehensive concept of reduced NO synthetic capacity compared with systemic arginine levels. Diminished GABR and high citrulline levels are associated with both development of significantly obstructive atherosclerotic CAD and heightened long-term risk for MACE.

Effects of water deficit stress, shade, weed competition, and kaolin particle film on selected foliar free amino acid accumulations in cotton, Gossypium hirsutum (L.).

Leaves of cotton plants, Gossypium hirsutum L., stressed by water deficit, reduced daylight, and weed competition, or treated with a kaolin wettable powder formulation were analyzed for levels of 17 free amino acids (FAAs) using reversed-phase high-performance liquid chromatography. Water deficit stress resulted in heightened free proline levels (49.9-fold, P < 0.001) that were correlated with diffusive resistance (seconds per centimeter). Five other FAAs increased, and the amounts of total free essential (for insect growth and development) amino acids and total FAAs also increased (P < or = 0.05). Cotton grown in 50% shade accumulated significantly more free arginine than control plants. In a small-plot weed competition assay, four FAAs increased and three FAAs decreased in association with weed competition, but because free proline levels were not altered and free arginine levels increased, other stresses aside from water deficit, possibly including shading by tall weeds, appear to have caused the changes. In a small-plot kaolin particle film assay, five FAAs were lower in cotton foliage sprayed weekly with kaolin. Because free proline was unaffected and free arginine was lower, it is possible that kaolin's reflectivity heightened light reception. The responses of free proline and arginine to the treatments used in these assays demonstrate that types and degrees of some stresses to cotton can be characterized by accumulations of certain FAAs. The study also demonstrates how some FAA levels can indicate degrees of cotton stress resulting from weed competition and from kaolin particle film application. Porometry and leaf water potential measurements assisted in corroborating some findings of the study.

Accumulation of free amino acids as an early indication for physiological stress (nitrogen overload) due to elevated ammonium levels in vital Stratiotes aloides L. stands

The relationship between the nitrogen and the free amino acid content in Stratiotes aloides L. was investigated for 11 healthy stands in the Netherlands. In the shoots, the mean free asparagine and free arginine levels were strongly correlated with the mean total N concentrations and the ammonium concentrations in the water layer. The percentage of total N present as free amino acids varied from 5.4 % to 27.5 % between the stands. In the stands with the highest total N levels, up to 92 % of the nitrogen in the free-amino acid pool consisted of asparagine and arginine. The results reveal that the accumulation of these N-efficient free amino acids was caused by increased ammonium availability in the environment. The accumulation of specific free amino acids is regarded as an early indication for N-stress in still healthy S. aloides stands.

Arginine requirement and status assessed by different biochemical indices in rainbow trout ( Salmo gairdneri R.)

Arginine status was assessed in rainbow trout fed zein/fish meal-based diets containing graded amounts of arginine (1 to 2.4% in steps of 0.2%) or different levels of lysine (0.8, 2.0 and 3.0%), using different biochemical indices. Patterns of changes in free arginine levels in plasma, muscle or liver were not sufficient to estimate arginine needs according to dose-response analysis. The relative incorporation of labelled arginine into muscle protein decreased up to a dietary arginine level of 1.4–1.6% and then was restored. The oxidation of arginine increased up to a dietary level of 1.4%. There was a large accumulation of radioactivity, probably linked to different catabolites of arginine, in the soluble pool of the muscle, above a dietary arginine level of 1.2%. The catabolism of arginine, assessed by other criteria such as plasma urea and urinary excretion of urea, increased when dietary arginine exceeded 1.4% but the urea pathway accounted for less than 50% of arginine catabolism. An alternative pathway of arginine metabolism, that of creatime synthesis, also increased with an increasing dietary supply of arginine. With the experimental diet used, it is concluded that the arginine requirement can be met by a total dietary supply of 1.2%. At higher levels of arginine supplementation, the level of dietary lysine should be above 2.0% of the diet.

RNA, Proteins and Polyamines During Tube Growth in Germinating Apple Pollen

Variations of RNA, protein, and free- and trichloroacetic acid-soluble bound polyamine levels were determined during tube growth in germinating Malus domestica Borkh. cv. Starkrimson pollen.During rehydration of pollen no marked differences were observed, whereas, during germination, RNA, proteins, and polyamines showed parallel decreases. At the same time, there was synthesis of RNA and polyamines as indicated by use of labeled precursors. The data indicate that during germination: (a) the genes for rRNA, tRNA, and probably mRNA are active; (b) the enzymes involved in polyamine biosynthesis are very active. High levels of free arginine during the first 15 minutes were observed, probably in response to a demand for this precursor in polyamine biosynthesis. Moreover, profiles of the variations in the specific activities of RNA and polyamines showed similar patterns. The results indicate that biosynthesis of RNA and polyamines precedes tube emergence. The possible role of these compounds, which are known to be released into the medium in the progamic phase of the fertilization processes, is considered.

Anaerobic metabolism of the common cockle, Cardium edule—IV. Time dependent changes of metabolites in the foot and gill tissue induced by anoxia and electrical stimulation

1. 1. The levels of adenylates, arginine phosphate, arginine and various other metabolites related to anaerobic metabolism were determined in foot and gills of Cardium edule during anoxia (incubation in oxygen-free sea water) up to 48 hr and after electrical stimulation of the foot muscle. 2. 2. In the foot the phosphagen was depleted quite rapidly in the first hours of anoxia. Free arginine levels rose while there was little octopine accumulation. d-Lactate appeared to be the predominant end product. Alanine and succinate were also produced and the concentration of aspartate decreased, suggesting this metabolite as precursor for succinate. In the gills, where no arginine phosphate was present, succinate production was higher than in the foot and exceeded lactate formation. 3. 3. Only a small decline in ATP occurred during anoxia and consequently, only moderate changes in the energy charge were observed in both tissues. 4. 4. Electrical stimulation of the foot also resulted in the breakdown of arginine phosphate and formation of mainly lactate and not octopine. 5. 5. Total ATP consumption during anoxia has been calculated to be more rapid during the first hours. The ATP consumption rate was reduced by a factor of 7.8 during 48 hr of anoxia. 6. 6. During the first 4 hr of anoxia about 60% of the total consumed energy (as ATP equivalents) was provided by the phosphagen, while later glycolysis contributed about 80%. During electrical stimulation about 75% of the energy supplied was derived from the phosphagen. 7. 7. A comparison of the C. edule results with the data during anoxia and exercise of the jumping cockle is made.

Effects of Arginine-Devoid Diets in Chronically Uremic Rats

There is evidence that the kidney has a major role in the formation of the arginine used for extrahepatic protein synthesis. The effects of arginine-free diets were studied, therefore, in female Sprague-Dawley rats made uremic by partial left-renal artery ligation and contralateral nephrectomy. Uremic and sham-operated control rats were fed diets with amino acids proportioned as in casein or similar isonitrogenous diets in which the arginine was replaced by glutamic acid and alanine. Weight gain and the food efficiency ratio were determined, and 6 weeks after nephrectomy, a pulse dose of 14C-guanido arginine was administered. The rats were killed 2 hours later, and the radioactivity of proteins in various tissues was determined. Free arginine levels in tissues were also measured. Control rats fed diets devoid of arginine had reduced growth and a low food efficiency ratio. Free arginine levels in tissues and 14C-arginine incorporation into tissue protein in these rats were not different from controls receiving arginine except that 14C-incorporation into brain protein was decreased. Uremic rats fed an arginine-containing diet had a reduced growth rate as compared to control rats, and 14C-incorporation into brain protein was less. In uremic rats, when arginine was removed from the diet, there was no further effect on weight gain but the plasma arginine level was decreased and the incorporation of 14C-guanido arginine into protein of muscle and of kidney was reduced. Hence, the effects of an arginine-free diet appears to be different in chronically uremic as compared to control rats.

Amino acids, soluble proteins, and isoenzyme patterns of peroxidase during the germination of jack pine

In germinating jack pine, changes in nitrogenous compounds were separated into two phases, the first, where through imbibition, seeds expanded but the prospective seedling remained enclosed by the haploid and nutritive female gametophyte (0 to 3 days), and second, when radicles emerged and only cotyledons remained in contact with the gametophyte (4 to 11 days).During imbibition, total soluble N in seeds dropped and the amino acid pool was dominated by high levels of free arginine. As levels of arginine N declined the greatest changes in percentage composition involved glutamic acid (gametophyte) and glutamine (embryo). Thereafter, arginine N accumulated. By 7 days, arginine N was recovered in seedlings primarily from cotyledons. High asparagine levels were observed in stems and roots as glutamine N in the emerging seedling declined.Protein reserves in the seedling were nearly depleted by 4 days. Total protein and, at later stages, the ratio of hexone bases to dicarboxylic acids was generally higher in the gametophyte than in the seedling. Soluble proteins of the embryo were separated into at least 18 bands by disc electrophoresis and contained peroxidase activity which increased strongly after the first week of germination. The increase of nine isoenzymes of peroxidase with mobilities towards the anode correlated with the histochemical localization of peroxidase at the emerging shoot and root tips and throughout the vascular tissues.

Relation of Dietary Cations to Arginine-lysine Antagonism and Free Amino Acid Patterns in Chicks

Broiler-strain chicks were fed from hatching to 4 weeks of age a basal purified diet containing 35% casein, 0.5% methionine and 1.5% glycine as sources of amino acids. The diets contained 1.2% arginine, 2.5% lysine, 0.4% potassium and had a cation to anion ratio of 1:1. Supplementation with either arginine·HCl or sodium and potassium salts of metabolizable acids produced marked growth stimulation. A combination of cations and arginine was even more beneficial but the effects were not additive. Not only did the cation supplement stimulate the growth rate to the same extent as 0.6% arginine, but it decreased the deficiency signs typical of arginine deficiency-ataxia and frizzled feathers. More significantly, both arginine and potassium acetate supplementation decreased plasma and muscle lysine, threonine and serine while increasing the levels of free arginine. A combination of the supplements gave plasma and muscle amino acid patterns highly similar to those observed in chicks fed a practical corn-soybean meal diet. It may be concluded that cation supplementation of this casein-based diet spares the arginine requirement and creates more favorable free amino acid patterns. It is postulated that the rate of arginine catabolism is decreased by the more positive cation balance.