Nitrogen metabolism of Picea glauca. IV. Metabolism of uniformly labelled 14C-L-arginine, [carbamyl-14C]-L-citrulline, and [l,2,3,4-14C]-γ-guanidinobutyric acid during diurnal changes in the soluble and protein nitrogen associated with the onset of expansion of spruce buds

1969 ◽  
Vol 47 (8) ◽  
pp. 771-783 ◽  
Author(s):  
D. J. Durzan
Keyword(s):  
Amino Acids ◽  
Nitrogen Metabolism ◽  
Picea Glauca ◽  
Free Amino ◽  
Neutral Fraction ◽  
Aminobutyric Acid ◽  
Diurnal Changes ◽  
Protein Nitrogen ◽  
Low Levels ◽  
Pool Sizes

In spring as white spruce buds started to expand, seasonal levels of proline were high and pool sizes of most free amino acids were maximal at sunset and sunrise. Uniformly labelled 14C-L-arginine, applied to buds at sunrise, was converted to citrulline via ornithine. [Carbamyl-14C]-L-citrulline was metabolized to argininosuccinate, arginine, and urea. These reactions indicated the presence at low levels of the Krebs–Henseleit or ornithine cycle. No convincing urease activity could be extracted or detected histochemically. Urease, added to extracts of buds exposed to radioactive L-arginine or L-citrulline, released 14CO2 confirming the presence of 14C-urea. L-Arginine was converted readily to ornithine, Δ1-pyrroline-5-carboxylic acid, and proline. The appearance of 14C in monosubstituted guanidines, e.g. γ-guanidinobutyric acid and others, which remained unidentified but proven not to be homoarginine, agmatine, argininic acid, nor γ-guanidinobutyramide, accounted more readily for the metabolism of arginine than did the ornithine cycle alone. L-Citrulline was metabolized via arginine to γ-guanidinobutyric acid and to several unidentified compounds that were not amino acids or related to monosubstituted guanidines. 14C-γ-Aminobutyric acid, a product of arginine degradation, was also derived from [l,2,3,4-14C]-γ-guanidinobutyric acid suggesting the presence of a heteroarginase. γ-Guanidinobutyric acid was translocated down the shoot with little distribution of 14C into other compounds.14C from arginine and citrulline and to a much lesser extent from γ-guanidinobutyric acid was recovered in the protein fraction mainly as arginine, glutamic acid, and proline. Maximal incorporation of 14C into protein was reached at or near midnight, then rapidly fell to noon of the following day. Incorporation of 14C into bud protein was out of phase with levels of total protein N and in phase with an increase of radioactivity in compounds of the anionic and neutral fraction, reflecting dramatically the complexity of the nitrogen metabolism of buds awakening from winter dormancy.

Nitrogen metabolism of Picea glauca. II. Diurnal changes of free amino acids, amides, and guanidino compounds in roots, buds, and leaves during the onset of dormancy of white spruce saplings

1968 ◽  
Vol 46 (7) ◽  
pp. 921-928 ◽  
Author(s):  
D. J. Durzan
Keyword(s):  
Amino Acids ◽  
Picea Glauca ◽  
Weight Basis ◽  
Aminobutyric Acid ◽  
Soluble Nitrogen ◽  
Diurnal Changes ◽  
Fresh Weight ◽  
Fresh Weight Basis ◽  
Plant Parts ◽  
Guanidino Compounds

In late August during the onset of dormancy in spruce, seasonal levels of soluble nitrogen, rich in arginine, were high. On a fresh weight basis, diurnal levels of total soluble nitrogen and most component amino acids in roots, buds, and leaves showed maxima, one at sunrise and another in the afternoon or near sunset.Arginine and glutamine in the different plant parts contributed 44 to 83% to the alcohol-soluble nitrogen. In buds and leaves, percentage of arginine remained high and decreased slightly at midday, whereas in roots a continual drop occurred. In all organs examined, changes in glutamine reflected the double maxima of total soluble nitrogen and were greatest in roots.On a fresh weight basis, most amino acids accumulated at sunrise and near sunset; however a few especially in leaves, increased at midday, e.g. glutamic and aspartic acid, lysine, γ-aminobutyric acid, and serine.Comparison of levels of free guanidino compounds in different organs showed remarkable out-of-phase patterns. Levels of these compounds are known from 14C-arginine studies to be closely related to the metabolism of arginine.

Nitrogen metabolism of Picea glauca. III. Diurnal changes of amino acids, amides, protein, and chlorophyll in leaves of expanding buds

1968 ◽  
Vol 46 (7) ◽  
pp. 929-937 ◽  
Author(s):  
D. J. Durzan
Keyword(s):  
Amino Acids ◽  
Picea Glauca ◽  
Moisture Stress ◽  
Rapid Expansion ◽  
Soluble Nitrogen ◽  
Diurnal Changes ◽  
Fresh Weight ◽  
Protein Nitrogen ◽  
Fresh Weight Basis ◽  
Diurnal Patterns

In spring, buds of spruce shoots under moisture stress contracted during the day and expanded at night. Increased water supply to roots removed the shrinkage of buds and stimulated rapid expansion. In leaves of buds about to break and under moisture stress, the alcohol-soluble nitrogen, high in arginine content, was maximal at midday, after midnight, and again at noon the next day. As a percentage of the soluble nitrogen, all compounds, except arginine, contributed most at sunset and again at sunrise. Other prominent amino acids included proline, alanine, γ-aminobutyric acid, and the amides glutamine and asparagine. Except for the amides, these and other compounds, present at lower levels, gave diurnal patterns similar on a fresh weight basis to arginine. Values for protein nitrogen were greatest at 2 p.m. followed by an increase of asparagine nitrogen, and again at 4 a.m., followed by an increase of glutamine nitrogen. At night the composition of newly synthesized protein increased significantly in aspartic acid, serine, glycine, alanine, leucine, and isoleucine. Chlorophyll a increased from 2 p.m. to 10 p.m., whereas chlorophyll b was present at lower levels and showed little diurnal variation.

Free Amino Acid and Haemolymph Concentration Changes in Sphaeroma Rugicauda (Isopoda) During Adaptation to a Dilute Salinity

1969 ◽  
Vol 50 (2) ◽  
pp. 319-326
Author(s):  
R. R. HARRIS
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Sea Water ◽  
Protein Nitrogen ◽  
Body Sodium ◽  
Concentration Changes ◽  
Total Body

1. Non-protein and protein nitrogen fractions of the isopod Sphaeroma rugicauda were measured in animals adapted to 100 and 2% sea water. 2. The non-protein nitrogen component was reduced in animals acclimatized to the lower salinity. 3. Free amino acids accounted for 88 and 74% respectively of the non-protein nitrogen in the two salinities. 4. In 2% sea water taurine, proline, glycine, alanine and glutamic acid showed the greatest decreases in concentration compared to the levels measured in animals adapted to 100% sea water. 5. The decrease in total free amino acids of animals acclimatized to 100% sea water and transferred to 2% sea water was measured. 6. The total free amino acid concentration is reduced to the 2% sea water level within 12 hr. after transfer. 7. Free amino acid, haemolymph sodium and total body sodium levels after transfer to 2% sea water were compared. 8. The asymmetry between the fall in haemolymph sodium concentration and the decrease in total body sodium under these conditions is thought to be due to a water shift from the haemolymph into the tissues. 9. It is suggested that the osmotic pressure of the cells falls at a slower rate than that of the haemolymph.

CHANGES IN PEACH TREES (cv. RED HAVEN) ATTACKED BY TAPHRINA DEFORMANS, WITH PARTICULAR REFERENCE TO NITROGEN METABOLISM IN INFECTED AND NON-INFECTED LEAVES

1967 ◽  
Vol 45 (4) ◽  
pp. 459-477 ◽  
Author(s):  
Vittorio Raggi
Keyword(s):  
Amino Acids ◽  
Nitrogen Metabolism ◽  
Free Amino Acids ◽  
Free Amino ◽  
Dry Weight ◽  
Infected Tissue ◽  
Diseased Plant ◽  
Glycolytic Activity ◽  
Protein Amino Acids ◽  
Peach Trees

Some of the changes induced by Taphrina deformans on metabolism (particularly the nitrogen metabolism) of peach leaves were studied. Observations were as follows. (1) Dry weight diminishes in the infected tissues, especially at the end of the cycle, whereas it remains almost unchanged in the non-infected tissues of the diseased plant. (2) Initially, the amount of total nitrogen, per gram of dry substance is clearly greater in the infected tissues than in the control, then it becomes lower during the differentiation of the asci, especially at the stage of full sporulation. Similar variations occur also, in a more attenuated form, in the non-infected tissues. (3) A considerable increase of the glycolytic activity is observed in the infected tissue especially during the period preceding the differentiation of the asci, and an increase of respiration, even though much more restricted, is observed also in the next period. In non-invaded tissues, an increase of glycolysis is noted along with a diminution of respiration. (4) The non-infected leaves weigh more than those of the control until the differentiation of the asci; after it, they have a clear drop up to the maturity of the asci, and a further revival at the end of the disease. (5) In the infected tissues, the content of free amino acids is always higher than in the control (with a maximum after sporulation), whereas in the non-infected ones it is generally lower. (6) The more important alterations in the pool of the free amino acids in invaded tissues consist in a scarcity, in percentage of the total, of alanine and glutamic acid, especially at the end of the disease, whereas proline, ornithine, glycine, and others increase, especially during the incubation period. In particular the glutamine–asparagines– threonine group reaches the highest value when sporulation has occurred. In the non-invaded tissues, the changes are more restricted. (7) The content of protein amino acids in infected tissues is generally lower than in the control, especially in the last phases of infection whereas in the non-invaded parts it is generally higher, except in differentiation of the asci. (8) In the infected tissue, the alterations of the quantitative relationships between the single protein amino acids (in percentage of the total) are not very great, but some diminutions and increases are recorded (diminution of alanine, glycine, leucine, etc.; increase of lysine, histidine, etc.); in the non-infected tissues, no noteworthy alterations were observed.

Effect of diet and infusion of volatile fatty acids into the rumen on the concentration of plasma free amino acids in sheep

1982 ◽  
Vol 48 (3) ◽  
pp. 519-526 ◽  
Author(s):  
J. R. Mercer ◽  
E. L. Miller
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino ◽  
Volatile Fatty Acids ◽  
Plasma Concentrations ◽  
Essential Amino Acids ◽  
Protein Nitrogen ◽  
Post Infusion ◽  
Limiting Amino Acid ◽  
The Mean

1. The effect of supplementing barley diets with urea (U), extracted decorticated groundnut meal (GNM) or Peruvian fish meal (PFM) on plasma free amino acid concentrations in sheep have been examined and the first limiting amino acid has been indicated by measuring the changes in the concentration of the plasma essential amino acids (PEAA) during a rumen infusion of a volatile fatty acid (VFA) mixture.2. Three wethers fitted with rumen and re-entrant duodenal cannulas were given isonitrogenous, isoenergetic diets containing (g/kg dry matter (DM)) U 20, GNM 106 or PFM 78, the crude protein (nitrogen × 6.25) contents being 139, 145 and 148 respectively. The sheep were fed hourly, the mean daily dm intake being 0.634 kg.3. Plasma concentrations of valine, threonine, lysine, isoleucine and leucine were linearly related to their concentrations in duodenal digesta.4. A VFA mixture was infused into the rumen for 6 h to supply (mmol/min) acetate 1.47, propionate 0.22 and n-butyrate 0.27. Blood samples were taken 6 h before, during and 12 h after the end of the infusion.5. The concentration of all PEAA decreased relative to the pre-infusion and post-infusion controls but there were no significant differences between diets.6. The mean decreases in concentration averaged over all three diets showed that the decrease in concentration of methionine (41.5%) was far greater than for any other essential amino acid suggesting that under these conditions methionine was the first limiting amino acid.

Variations in the concentrations of free amino acids in the plasma of the dairy cow at parturition

1972 ◽  
Vol 39 (3) ◽  
pp. 355-364 ◽  
Author(s):  
R. Verbeke ◽  
E. Roets ◽  
G. Peeters
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Free Amino ◽  
Milk Protein ◽  
Sampling Period ◽  
Aminobutyric Acid ◽  
Amino Acid Utilization ◽  
Amino Acid Levels ◽  
The Mean ◽  
Peak Value

SummaryThe plasma levels of individual amino acids were studied in 6 dairy cows from 4 days before to 3 days after calving. During this sampling period, the concentrations of 13 amino acids showed significant changes. The levels of several amino acids were depressed markedly in the sample collected immediately before calving. Following parturition, the concentration of most amino acids gradually returned to values obtained 3 days before calving. The glutamine and alanine contents of the plasma rose to a peak value 1 day after calving and subsequently decreased. The mean concentrations of glycine and α-aminobutyric acid did not change before parturition but rose significantly thereafter. These observations are discussed in terms of amino-acid utilization for milk protein synthesis and gluconeogenesis at the onset of lactation. The changes in plasma amino acid levels appear to be synchronized with those reported for prolactin and progesterone in the 24 h before parturition. This may indicate an important influence of both hormones on the lactogenic process in the cow. The highly significant correlations obtained between the concentrations of 14 individual amino acids are discussed.

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