EDTA-promoted exudation of 14C-labeled compounds from detached cottonwood and bean leaves as related to translocation

1977 ◽  
Vol 7 (2) ◽  
pp. 277-284 ◽  
Author(s):  
Richard E. Dickson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Organic Acids ◽  
Organic Acid ◽  
Sieve Tube ◽  
Total Activity ◽  
Mature Leaves ◽  
Edta Solution ◽  
Chloroform Methanol ◽  
Bean Leaves

Mature and developing cottonwood (Populusdeltoides Bartr.) and bean (Phaseolusvulgaris L.) leaves were photosynthetically labeled for 30 min with 14CO2. Radioactive compounds in exudate obtained by placing the cut petioles in 20 mM Na2EDTA for 6 h were compared with those found in chloroform–methanol–water extracts of leaf lamina and petiole. Of the total activity lost in 6 h, 54% was recovered in the exudate from mature bean leaves compared with 3% recovered from cottonwood leaves. Smaller amounts were recovered in exudate from developing leaves compared with mature leaves of both species. Thus EDTA was not very effective for maintaining translocation rates in excised cottonwood leaves. Most of the radioactivity in the exudate was in sugars, indicating relatively pure sieve tube contents. However, radioactive amino acids and organic acids were always present, particularly in exudate from developing leaves. These amino and organic acids could either be derived from metabolism outside of the phloem with subsequent leakage into the EDTA solution, or be a component of the normal translocation stream. Of the total activity in exudates from developing cottonwood leaves, 17% was found in the amino acid and 33% was found in the organic acid fraction compared with 7% and 5% in these fractions, respectively, from developing bean leaves. The distribution of activity in the sugar, amino acid, and organic acid fractions of cottonwood petiole extract was similar to that found in the exudate. In contrast, proportionally less sugar and more amino acids and organic acids were labeled in bean petiole extract compared with the exudate, indicating lateral movement and metabolism in the bean petiole.

The Formation of Homoserine from Methionine in Germinating Peas

1971 ◽  
Vol 49 (7) ◽  
pp. 795-798 ◽  
Author(s):  
D. R. Grant ◽  
E. Voelkert
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Amino Acid ◽  
Organic Acid ◽  
Free Amino Acid ◽  
Free Amino ◽  
Total Activity ◽  
Acid Fraction ◽  
Direct Pathway ◽  
Pea Seedlings

L-Methionine-1-14C was fed through the roots to 6-day-old pea seedlings. After 10 h over 80% of the absorbed radioactivity was recovered in the free amino acid fraction, 8% in the extracted proteins, 5% as carbon dioxide, and 2.2% in the organic acid fractions. Analysis of the amino acids revealed that only 24% of the total activity was recovered as methionine, 40% as homoserine, 10% as isoleucine, and smaller but significant amounts of aspartate, O-acetylhomoserine, and cystathionine. Dilution values strongly imply that aspartate is not an intermediate in the extensive conversion of methionine to homoserine; rather a more direct pathway is involved.

105 Feed Additives That Optimize Nitrogen Bio-availability in Nursery Pigs Fed Reducing Crude Protein Diets

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 103-103
Author(s):  
Tsung Cheng Cheng Tsai
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Organic Acids ◽  
Organic Acid ◽  
Crude Protein ◽  
Nutrient Digestibility ◽  
Nutrient Absorption ◽  
Feed Additives ◽  
Peptide Transporter ◽  
Amino Acid Requirement

Abstract Reducing dietary crude protein in early nursery has been suggested as a way to conquer the challenge of post-weaning diarrhea. In order to meet the amino acid requirement in RCP diets, feed grade amino acids are typically used, but the detrimental effect on growth performance associated with the aggressive usage of these amino acids resulted in the establishment of dietary limits. Given the fact that protein deposition rate is the highest in young pigs, lower amino acid consumption could slow the growth rate and feed efficiency in early nursery phase. Therefore, identifying feed additives that increase nutrient retention not only can further reduce dietary nitrogen but also maintain GI tract health. Among all feed additives that exert improvements on nutrient digestibility, peptide and organic acids will be discussed here. Peptide, a di- tri amino acid, is absorbed more efficiently than free amino acids in the small intestine through a peptide transporter at the enteric site. In addition, aside from meeting the amino acid requirement, the bioactive peptide possesses functions such as antimicrobial, antioxidant, anti-inflammatory, and as a stimulated Peptide transporter associated with nutrient absorption. Hence, a dietary peptide can help pigs meet the nutrient requirement in RCP diets. Organic acids, on the other hand, have been found to lower gastric pH which improves nutrient absorption, alters microbiome structure (via bacteriostatic and bactericidal) and promotes the growth and health of animals. In addition, organic acids are a ready energy source which is especially critical since nutrient supply disruption, due to low intake during early weaning, is commonly found in weaning pigs. It is noteworthy that variations of growth-promoting effects do exist for both peptide and organic acid products. Thus, understanding the mode of action and response of dietary peptide and organic acid supplements when used across different farm settings is important to help producers decide when to transfer to an antibiotic-free, low zinc operation.

THE NATURE OF PHOTOSYNTHATE IN PINUS STROBUS SEEDLINGS

1962 ◽  
Vol 40 (5) ◽  
pp. 669-676 ◽  
Author(s):  
T. Shiroya ◽  
G. Krotkov ◽  
C. D. Nelson ◽  
V. Slankis
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Organic Acids ◽  
Organic Acid ◽  
Pinus Strobus ◽  
Insoluble Residue ◽  
Two Dimensional ◽  
Initial Separation ◽  
Exchange Resins ◽  
Soluble C

Representatives of C14-labelled sugars, amino acids, and organic acids were placed on several different kinds of exchange resins and their absorption and elution from such resins was determined. From the data obtained, a combination of IR 120 in the H+ form and IRA 400 in the formate form was selected for the initial separation of pine extracts into their sugar, amino acid, and organic acid fractions. These fractions were resolved further by two-dimensional paper chromatography.Two-year-old Pinus strobus seedlings were illuminated in C14O2 for 8 hours either at 2500 or 250 ft-c. Then their shoots were extracted with 80% ethanol and the distribution of C14 in various components of the photosynthate was determined, as described above.The results obtained were essentially the same for seedlings illuminated either with 2500 or 250 ft-c. Not more than 10% of the absorbed C14 were found in the ethanol-insoluble residue. About 98% of the ethanol-soluble C14 were found in the sugar fraction, with the remaining 2% being about equally divided between the amino and organic acids. Sucrose formed about 75% of the sugar fraction, with glucose and fructose making up additional 20%. Only small amounts of raffinose were found.

The Xylem Sap of Maize Roots: Its Collection, Composition and Formation

1988 ◽  
Vol 15 (4) ◽  
pp. 557 ◽  
Author(s):  
MJ Canny ◽  
ME Mccully
Keyword(s):  
Amino Acids ◽  
Organic Acids ◽  
Organic Acid ◽  
Aspartic Acid ◽  
Xylem Sap ◽  
Great Variability ◽  
Reduced Pressure ◽  
Transpiration Stream ◽  
Maize Roots ◽  
Total Amino Acids

Three methods of sampling xylem sap of maize roots were compared: sap bleeding from the stem cut just above the ground; sap bleeding from the cut tops of roots still undisturbed in the ground; and sap aspirated from excavated roots under reduced pressure. The bleeding saps were often unobtainable. When their composition was measured with time from cutting, the concentrations of the major solutes approximately doubled in 2 h. Aspirated sap was chosen as the most reliable sample of root xylem contents. Solute concentrations of the saps showed great variability between individual roots for all solutes, but on average the concentrations found (in �mol g-1 sap) were: total amino acids, 1.8; nitrate, 1.8; sugars (mainly sucrose), 5.4; total organic acids, 18.3. Individual amino acids also varied greatly between roots. Glutamine, aspartic acid and serine were generally most abundant. The principal organic acid found was malic, approximately 8 �mol g-1. From these analyses the ratios of carbon in the fractions (sugars : amino acids : organic acids) = (44 : 6 : 50). 14Carbon pulse fed to a leaf appeared in the root sap within 30 min, rose to a peak at 4-6 h, and declined slowly over a week. During all this time the neutral, cation and anion fractions were sensibly constant in the proportions 86 : 10 : 4. The 14C therefore did not move towards the equilibrium of 12C-compounds in the sap. It is argued that the results do not support a hypothesis of formation of amino carbon from recent assimilate and reduced nitrate in the roots and an export of this to the shoot in the transpiration stream.

Amino Acid Metabolism in Plants. III. Purification and Some Properties of a Multispecific Aminotransferase Isolated from Bushbean Seedlings (Phaseolus vulgaris L.)

1972 ◽  
Vol 50 (7) ◽  
pp. 813-829 ◽  
Author(s):  
J. C. Forest ◽  
F. Wightman
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Aspartate Aminotransferase ◽  
Soluble Protein ◽  
Specific Activity ◽  
Aromatic Amino Acids ◽  
Total Activity ◽  
Aminotransferase Activity ◽  
Aromatic Aminotransferase

The development of aromatic aminotransferase activity was examined in cotyledons, roots, and shoots of bushbean seedlings growing under light or dark conditions for the first 2 weeks after germination. All three aromatic amino acid – α-ketoglutarate aminotransferase activities were found to have similar patterns of development in comparable organs grown under the two environmental conditions, and the changes in levels of activity appeared unrelated to variations in the endogenous amounts of free aromatic amino acids in the organs of these seedlings. The highest total activity for all three transamination reactions was found in the shoots of light-grown seedlings after 14 days, whereas the aminotransferases showing highest specific activity were found in roots of both kinds of seedlings after 8 days of growth. The intracellular distribution of the three aromatic aminotransferase activities and of aspartate aminotransferase activity was investigated by differential centrifugation of root homogenates. Only a total of 10% of these two activities was found in the two particulate fractions; the soluble protein in the final supernatant fraction accounted for almost 90% of the total aromatic and aspartate aminotransferase activities.The aromatic aminotransferase in the soluble protein fraction from seedling roots was purified about 600-fold by pH precipitation, ammonium sulfate fractionation, and Sephadex chromatography, and the recovery obtained was 30–35% based on total activity. It was observed that the specific activity for aspartate–α-ketoglutarate aminotransferase increased proportionally to the increase in aromatic aminotransferase activities during the different steps of purification. Gel electrophoresis of the purified fraction revealed only one protein band which corresponded to the product-specific stained band for the three aromatic aminotransferase activities assayed on other gels. The molecular weight of the purified aminotransferase was found to be about 128 000 daltons and its Stokes radius was calculated to be 43 ± 3 Å. The pH optima for the three aromatic aminotransferase activities and for aspartate aminotransferase activity were all found to be 8.5. The purified enzyme showed no specific requirement for pyridoxal phosphate and an examination of its amino acid substrate specificity revealed that it was able to catalyze transamination of L-aspartic acid, L-phenylalanine, L-tyrosine, and L-tryptophan when α-ketoglutarate was provided as amino group acceptor. The enzyme was also found to catalyze transamination of L-glutamic acid when oxaloacetate was used as amino group acceptor, but neither pyruvate nor glyoxylate were utilized as amino acceptors for transamination of any of the amino acids examined. The enzyme was found to catalyze transamination of aspartic acid with much greater velocity than its rate of reaction with any of the three aromatic amino acids, and the inclusion of aspartic acid in a reaction medium at equimolar concentration with any one of the three aromatic amino acids resulted in strong inhibition of the aromatic aminotransferase activity of the enzyme. All the evidence indicates that the soluble protein fraction purified from bushbean roots contained only one aminotransferase which was able to catalyze the transamination of five L-amino acids. The demonstration of the substrate multispeciftcity of this pure enzyme represents the first evidence for a multispecific aminotransferase in plants.

Translocation and Metabolism of MAA-14C in Johnsongrass and Cotton

Weed Science ◽  
1969 ◽  
Vol 17 (4) ◽  
pp. 421-427 ◽  
Author(s):  
M. M. Sckerl ◽  
R. E. Frans
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Gossypium Hirsutum ◽  
Organic Acid ◽  
Biosynthetic Pathway ◽  
Sorghum Halepense ◽  
Acid Fraction ◽  
Methanol Extracts ◽  
Xylem Tissue

Radioautographs showed that root uptake of14C-methanearsonic acid (MAA-14C) by johnsongrass (Sorghum halepense(L.) Pers.) from nutrient solution was rapid and translocation into all portions of the plant occurred within 4 hr after treatment. Basipetal and acropetal translocation of foliar and stem-applied MAA-14C occurred in both johnsongrass and cotton (Gossypium hirsutumL., var. Rex smooth leaf), indicating that movement of the herbicide probably occurs in both phloem and xylem tissue. However, acropetal movement of MAA in both plants occurred at a higher rate than basipetal movement, and basipetal movement in cotton was not as rapid as in johnsongrass. Methanol extracts of MAA-14C johnsongrass were chromatographed. Radioactive spots with Rfvalues different from the MAA-14C standard were observed. Use of location reagents on the chromatographs suggested that MAA-14C may complex with either a sugar or organic acid or both. Amino acid fractions were prepared from methanol extracts of both plants. An MAA metabolite, with a positive reaction to ninhydrin, was located on chromatographs spotted with the amino acid fraction from johnsongrass but was not present in the cotton fraction. A comparison of Rfvalues suggests that the metabolite may be a combination of the MAA molecule with histidine or one of its analogues. Spectrophotometric determination showed a build-up of amino acids in MAA-treated johnsongrass but not in cotton. The increased levels of amino acids in johnsongrass suggest that the MAA metabolite may be blocking a protein synthesis pathway, or some other unknown biosynthetic pathway.

Studies of intermediary metabolism in radish cotyledons. Turnover of photosynthetic products in 14CO2 pulse-chase experiments

1970 ◽  
Vol 48 (6) ◽  
pp. 1191-1198 ◽  
Author(s):  
A. Caballero ◽  
E. A. Cossins
Keyword(s):  
Amino Acids ◽  
Organic Acid ◽  
Incubation Medium ◽  
Growth And Development ◽  
Sugar Phosphate ◽  
Carbon 14 ◽  
Mature Leaves ◽  
Photosynthetic Products ◽  
Sugar Phosphates ◽  
Kinetics Of

Ability of 11-day-old radish cotyledons to carry out photosynthesis has been examined by supplying 14CO2 to cotyledon disks for periods ranging from 30 s to 20 min. Carbon-14 was rapidly incorporated into malate, citrate, sugar phosphates, and a number of amino acids. The kinetics of 14C incorporation suggest that carbon initially enters components of the organic acid and sugar phosphate fraction, being then rapidly transferred to the amino acids and sugars. In pulse-chase experiments, illuminated cotyledon disks were incubated with 14CO2 for 30 min then transferred to air containing 12CO2 for periods up to 240 min with illumination. During such postpulse incubations, considerable losses of 14C occurred from most of the principal compounds labeled during the chase incubation. As these losses were not entirely accounted for by losses of label to the incubation medium they can largely be attributed to metabolic turnover of these compounds. It is concluded that, in general, the photosynthesis of radish cotyledons is similar to that of mature leaves and of physiological significance as a route for synthesis of several important cellular constituents required for seedling growth and development.

scholarly journals Incorporation of radioactive carbon from [14C] alanine in the rumen of a cow given feed containing urea as the sole source of nitrogen

1980 ◽  
Vol 52 (1) ◽  
pp. 69-74
Author(s):  
Eeva-Liisa Syväoja ◽  
Matti Kreula
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Amino Acid ◽  
Butyric Acid ◽  
Volatile Fatty Acids ◽  
Rumen Fluid ◽  
Cell Mass ◽  
Total Activity ◽  
Considerable Proportion ◽  
Trichloracetic Acid

The utilisation of exogenic amino acid in a cow given feed containing urea and ammonium salts as the sole sources of nitrogen was studied by means of intraruminal administration of [14C]alanine. The labelling of the trichloracetic acid-precipitated bacterial cell mass, the main volatile fatty acids (acetic, propionic and butyric acid) and a number of isolated amino acids after 1,3, 8 and 26 h was determined. The rumen micro-organisms rapidly incorporated the [14C]alanine into their cellular constituents. After the above-mentioned times the microbial cell mass was found to contain 47.4, 49.7, 70.0 and 80.0 % of the total activity of the rumen contents. Although the carbon skeleton of alanine can be used for the formation of many amino acids the rumen bacteria studied were shown to utilise only small amounts of this amino acid in their synthesis of Asp, Glu, Tyr and Phe. The combined label present in these 4 amino acids was 1.5, 1.9, 2.9 and 5.5 % of the total activity of the rumen fluid at the stated times. A considerable proportion of the [14C]alanine was degraded to volatile fatty acids: label present in acetic, propionic and butyric acid totalled 40.8, 32.3, 23.0 and 5.0 % of that in the rumen fluid. Of these, acetic acid had the strongest labelling after 1 and 3 h, and propionic acid the weakest at all stages.

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