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At least 37 records · Page 2Linked to original sources
PubMed1978

Nitrogen retention of young men who consumed selection patterns of essential amino acids at a constant nitrogen intake.

Six patterns of essential amino acids were devised to represent different sources or combinations of protein based on a daily intake of 6.0 g of nitrogen from these sources. In each diet, cereals furnished 70% and a specially designed amino acid mixture 30% of the total nitrogen. Nitrogen retention of young men who consumed amino acids equivalent to combinations of rice and soy or egg and potato did not differ from the pattern of egg, and these patterns were superior to a combination of rice and wheat; egg also was superior to corn plus beans and wheat plus milk. Relative amounts and proportions of essential amino acids could be modified without depressing nitrogen retention until one amino acid became limiting or the pattern became imbalanced. Therefore, more than one pattern of amino acids should be recognized as useful for adult human subjects; both minimal and total amounts of essential amino acids need to be considered.

Adult↗
PubMed1979

[Use of the combined Kjeldahl-wet digestion/Berthelot-reaction for determining nitrogen in biological materials. 2. Design and testing of a partially automated apparatus for routine determination of nitrogen].

The authors describe the design and the mode of operation of a partially automated analyzer system, based on the combination of the Kjeldahl wet digestion with the Berthelot reaction, for the determination of nitrogen in biological materials. The results from three years of operation are discussed from the view-points of variability of the materials to be tested, of accuracy and of precision. This analytical technique (with an accuracy of 98% and a precision of 4%) is suited for determining amino and amido nitrogen as well as non-aromatically bound ring nitrogen. The statistical evaluation of the analytical results revealed that the deviation of the measured values is mainly caused by the high-temperature digestion.

Amides↗
PubMed1977

[Studies on the determination of the part of bacterial nitrogen in relation to total nitrogen content in the duodenum of cows].

A method for estimation of content of bacterial nitrogen in duodenal intestine was described. The method of HUTTON et al. (1971) in modificated form for the own research was the best method. In two trials roughage (chopped dried forage) and ground corn were given to cows with duodenal bridge fistula in different order (90 min-intervall). Portion of bacterial nitrogen to total nitrogen was 72.5% (corn leads to roughage) and 64.7% (roughage leads to corn).

Animal Feed↗
PubMed1978

[Nitrogen and amino acid absorption in swine. 3. Endogenous secretion and absorption of nitrogen].

The endogenous nitrogen in the duodenum and the distal segment of the small intestine of 3 fistulated pigs fed a 15-N-labelled feed protein was determined using the isotope dilution technique. Over 24 hours, the endogenous N secretion was found at least 12.5 g at the end of the duodenum. For the upper segment of the small intestine, a statistically secured correlation between endogenous nitrogen and chyme amount was found to exist. It was possible to determine the true and apparent absorption of the nitrogen for both individual segments of and the whole digestive tract.

Amino Acids↗
PubMed1977

Studies on the purification of wastes from the nitrogen fertilizer industry by intensive algal cultures. IV. growth of Chlorella vulgaris in wastes with high nitrogen content in continuous and intermittent light.

The growth and utilization of nitrogen by intensive Chlorella vulgaris in wastes from production of urea, containing 1300 mg NH4+-N and 4000 mg urea-N/1, was investigated. In these conditions only Chlorella vulgaris AA strain, adapted to high concentrations of ammonia nitrogen, was able to grow. The elimination of nitrogen by continuous cultures was 750 mg urea-N/1 with 5-day flow rate. A considerable part of the urea was hydrolized by urease bacteria and removed in the form of NH3. The effect of intermittent light on the growth of algae was also studied. The better growth than in continuous light, was obtained with alternate one hour periods of light and darkness. Good results were also obtained with the use of 12 hour light and 12 hour darkness.

Ammonia↗
PubMed1979

Effect of high concentrations of nitrogen on mixed populations of nitrifying bacteria isolated from industrial nitrogenous wastewaters.

The effect of high concentrations of different forms of nitrogen (NH4+, NO2-, NO3- and urea N) on nitrification by mixed populations of nitrosobacters isolated from nitrogen fertilizer plant wastewaters and nitrobacters isolated from effluents from a biological bed treating these wastewaters was determined. The inhibitory activity (within the concentration values for industrial wastewaters) of only the reaction products was observed, i.e. nitrites for nitrification phase I and nitrates for nitrification phase II. A mixed population of phase II nitrifying bacteria is highly resistant to high concentrations of ammonia nitrogen (50% inhibition at 3,000 mg N/l).

Ammonia↗
PubMed2026

Natural variation in BRN1 enhances nitrogen sensitivity to improve rice nitrogen use efficiency.

Green Revolution rice varieties deliver high yields but require excessive nitrogen (N) fertilizer and show diminished N responsiveness, severely reducing nitrogen-use efficiency (NUE). To dissect the molecular basis of low N sensitivity in modern cultivars, we conducted a genome-wide association study (GWAS) for biomass response to N (BRN), a trait tightly linked to N sensitivity, using a diverse rice germplasm panel. We identified BRN1 as a key regulator of N-dependent biomass accumulation that regulates NLP3, a master transcription factor governing nitrate signaling. Under elevated N supply, the strigolactone signaling repressor D53 accumulates substantially and interacts with BRN1 to repress NLP3 transcription, thereby reducing rice N response. Notably, the high-response BRN1H allele encodes a more stable protein that alleviates D53-mediated suppression. Introgression of this allele into modern cultivars significantly enhanced N sensitivity and grain yield under both low and high N conditions. Our findings establish a D53-BRN1-NLP3 regulatory module controlling rice NUE, providing a target for rice breeding to sustain high productivity with improved resource sustainability.

Oryza↗
PubMed1979

An analysis of temporal patterns in urinary nitrogen excretion of young adults receiving constant diets at two nitrogen intakes for 8 to 11 weeks.

The temporal pattern of daily urinary nitrogen (UN) excretion was investigated in 21 young adult men and women who participated in two metabolic studies involving constant diets and lasting 8 to 11 weeks. For one group (16 subjects), nitrogen (N) intake was about 280 mg N/kg per day (mixed animal and plant protein sources) for 8 weeks; for the second group (five subjects), N intake was about 90 mg N/kg per day (egg protein) for 11 weeks. Two mathematical models were examined to determine how well they described the variations in UN. The first modeled only random variability while the second added a component of serial correlation (correlation between successive daily observations). After correcting the UN data for linear trend, to minimize effects of possible alterations in body composition, only two of the 21 subjects showed significant serial correlation of daily UN. Moreover, it is shown that any serial correlation undetectable in these data would not be of practical importance in estimating UN levels in short-term dietary experiments. It is concluded that the interpretation of metabolic N balance measurements involving constant N intakes over relatively short dietary periods in not complicated by cyclic, time-dependent variations in UN.

Adolescent↗
PubMed1975

Nitrogen metabolism in bears: urea metabolism in summer starvation and in winter sleep and role of urinary bladder in water and nitrogen conservation.

Three bears were studied under conditions of (1) no food but access to water for 2 weeks and (2) no food or water for 3 weeks. During starvation in summer, the bears could not inhibit the net production of urea but used lean body mass; when denied access to water as well, the bears became dehydrated and azotemic. Urea was continuously formed and degraded in the winter. Arginase activity in liver increased in winter sleep; hepatic steatosis and inflammatory reactions were also noted. The urinary bladder readsorbed labeled urea and D20 in winter; the rate of absorption of urea was equal to the rate of excretion of it into the bladder. The ability to preserve lean body mass during winter sleep apparently is a special mechanism associated with the induction of winter sleep. Bears cannot duplicate this feat during summertime starvation. In winter sleep, urea is formed and degraded but the nitrogen produced is conserved in some manner that maintains the total nitrogen pool constant. The urinary bladder plays a central role in maintaining the state of winter sleep by absorbing water and solute at a rate equal to their entry into the urinary bladder.

Animals↗
PubMed1975

Metabolic effects of antisickling amounts of nitrogen and nor-nitrogen mustard on rabbit and human erythrocytes.

Nitrogen mustard (NH2) and Nor-nitrogen mustard (Nor-HN2) both inhibit the polymerization of deoxyhemoglobin S in solution and in intact erythrocytes. Metabolic studies were undertaken to determine the feasability of an extracorporeal treatment with these or related agents. Glucose utilization, hexose monophosphate shunt activity, methemoglobin reduction, and incubation with acetylphenylhydrazine for Heinz body formation were performed, as well as specific assays for hexokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase, glutathione reductase, ATP, reduced glutathione (GSH), and survival of autologous mustard-treated cells in rabbits. HN2 was found to enter red cells rapidly and bind to intracellular contents. Metabolic studies revealed no significant inhibition or alteration of function by Nor-HN2 at 10 mg/ml of whole blood. Rabbit red cell survival was also normal. HN2, however, inhibited glutathione reductase and blocked the free sulfhydryl group of GSH by forming serveral addition products of alkylated GSH. Heinz body test with acetylphenylhydrazine became positive in HN2-treated cells, and rabbit red cell survival was shortened considerably in the concentration range used to inhibit sickling. Ascorbic acid stimulation of the hexose shunt pathway was inhibited by HN2, but methylene blue stimulation remained unaffected. 14-C-HN2 remains bound to red cells in vivo, and the disappearance of radioactivity is similar to that found with 14-C-DFP (disopropylfluorophosphate). Oxygen affinity of both HN2 and Nor-HN2 treated human red cells remains virtually the same as that found in control samples. It is concluded that Nor-HN2 may be a suitable agent for an extracorporeal therapy, and that each mustard needs to be evaluated individually for its antisickling effects and its suitability for extracorporeal use.

Animals↗
PubMed2026

Wheat breeding during and after the "green revolution" contributed to the reduced use of elite nitrogen metabolism alleles linked to nitrogen use efficiency.

The wheat "Green Revolution (GR)" that occurred from the 1960s to the 1970s significantly enhanced the harvest index and resistance to lodging, thereby increasing grain production, but at the cost of reduced nitrogen (N) use efficiency (NUE) in wheat. The NUE of wheat is mainly regulated by N metabolism genes (NMGs). However, the evolutionary process of NMGs during GR and post-GR wheat breeding, as well as which of them affect NUE, remains unclear. Here, we collected 265 wheat varieties that were released before, during, and after the GR and investigated grain yield per plant and 24 other traits under different N supply conditions. Next, we identified the genotypes of these wheat varieties using a 100 K targeted sequencing array. Then, we systematically analyzed the signatures in the genomes of GR and post-GR released varieties compared with pre-GR released varieties through population divergence (Fst) and nucleotide diversity (π) ratio analyses, and found that 41 NMGs were located within the selective sweep regions during the GR and post-GR breeding. We further identified 118 quantitative trait loci (QTLs) involved in regulating NUE through genome-wide association studies (GWAS). Four NMGs-NRT1 AND PEPTIDE TRANSPORTER FAMILY 2.7-D (TaNPF2.7-D), TaNPF2.3-D, TaNPF2.7 L-D, and QUASIMODO2-B (TaQUA2-B)-were located within overlapping regions of selective sweeps and NUE-related QTLs. Notably, the elite haplotypes of these genes for NUE are less utilized in GR and post-GR released cultivars. Furthermore, we found that TaNPF2.7-D positively regulates nitrate exudation as well as the wheat development. Collectively, our findings uncover an important reason for the reduction in NUE in modern cultivars and provide a valuable resource for improving wheat NUE.

Triticum↗
PubMed1978

Studies on enzymes of nitrogen metabolism, and nitrogen end products in the developing chick (Gallus domesticus) embryo.

1. A total of 450 fertilized eggs were used to study the concentrations of uric acid, urea and ammonia in allantoic and amniotic fluids, and some enzymes of nitrogen metabolism in the liver and kidney during the development of the chick embryo from the 5th to 21st day of incubation. 2. Concentrations of the compounds studied were higher in allantoic fluid. The molar concentration of allantoic uric acid increased steadily with time. The pattern of urea and ammonia in both allantoic and amniotic fluids were the same. 3. Arginase (E.C.3.5.3.1) activity in both embryonic kidney and definitive kidney was higher than that in the liver. The specific activity of arginase (mumole urea formed/hr per g wet wt kidney) dropped during development. 4. Little arginine synthetase activity (argininosuccinate synthetase, E.C.6.3.4.5; and argininosuccinate lyase, E.C.4.3.2.1) was found in kidney, but none in the liver. 5. The complete urea cycle function was absent in both the liver and the kidney of the chick embryo.

Animals↗
PubMed1975

Protein requirements of men in a hot climate: decreased urinary nitrogen losses concomitant with increased sweat nitrogen losses during exposure to high environmental temperature.

In two separate experiments 8 healthy young men were given an egg-milk formula at a level of 0.7 g protein/kg per day, and were exposed to high environmental temperature (34--37 C, 7 hours daily) or cool temperature (21--26 C, all day), alternately. In the first experiment a 16-day hot period was followed by a 20-day cool period and finally by a 20-day hot period. Daily urinary nitrogen (N) loss of the last 8 days of cool period, 82.2 mg/kg, was significantly higher than that of the last 8 days of the 20-day hot period 69.7 mg/kg. Daily skin N loss was significantly lower during the last 8 days of the cool period (3.5 mg/kg) than during the last 8 days of the 20-day hot period (11.9 mg/kg). Urinary N and skin N lossess were negatively correlated (r equal to -0.905) in these periods. In the second experiment a 28 day hot period was followed by a 20-day cool period. Skin N loss diminished from 12.3 mg/kg daily during the last 12 days of the 28-day hot period to 4.1 mg/kg during the last 12-days of the cool period. At the same time, urinary N loss increased significantly from 81.4 mg/kg during the 28-day hot period to 95.2 mg/kg during a cool period. Urinary N and skin N losses were again negatively correlated (r equal to -0.620) during these periods. Results of these studies indicate that when skin N loss increases during high temperature, urinary N loss decreases gradually, but total N loss does not increase.

Adult↗
PubMed1978

Effect of fiber from fruits and vegetables on metabolic responses of human subjects I. Bowel transit time, number of defecations, fecal weight, urinary excretions of energy and nitrogen and apparent digestibilities of energy, nitrogen, and fat.

Twelve men 37 to 58 years of age consumed two diets for a period of 26 days each in a cross-over design. The high fiber diet contained fruits and vegetables and the lower fiber diet contained fruit and vegetable juices. Neither diet contained whole grain cereals or nuts. Some nutrients were added to the low fiber diet in order to make the diets equivalent insofar as possible in all respects except fiber. The inclusion of fruits and vegetables in the diet decreased bowel transit time, increased fecal weight, increased number of defecations, increased fecal excretions and decreased apparent digestibilities of energy, nitrogen, and fat. Six of the 12 subjects had diastolic blood pressure of 80 or more when consuming the low fiber diet. The diastolic blood pressures of these six men were significantly lower when the high fiber diet was consumed.

Adult↗
PubMed1979

Nitrogen fixation by Rhizobium sp. 32H1. A morphological and ultrastructural comparison of asymbiotic and symbiotic nitrogen-fixing forms.

The induction of nitrogenase (C2H2) activity in asymbiotically cultured Rhizobium sp. 32H1 was found to be associated with morphological changes in the cells which were more pronounced than those seen in bacteroids. Polyphosphate granules were found in both bacteroids and cultured cells, but poly-beta-hydroxybutyrate vesicles were almost absent in bacteroids but were present in cultured cells. Freeze-etching techniques revealed no differences between the asymbiotically cultured nitrogen-fixing forms and bacteroids in that both the cell wall and cytoplasmic membrane cleavage planes were normal for gram-negative bacteria.

Cytoplasmic Granules↗
PubMedDate not supplied

[Effect of nitrogen-containing compounds on hydrogen light emission and nitrogen fixation by purple bacteria].

The cells of Rhodospirillum rubrum and Thiocapsa roseopersicina grown in media containing glutamate and arginine, respectively, as well as under conditions of nitrogen fixation evolve H2 in the light. If the cultures were grown in media with NH4+, NO3-, urea, glutamine or asparagine, hydrogen photoevolution by the cells and acetylene reduction started after the lag-phase and proceeded at a low rate. Extracts of such cells did not display the activity of nitrogenase which could be assayed by the ATP-dependent evolution of H2 from dithionite. The data obtained confirm the fact that hydrogen photoevolution by purple bacteria involves nitrogenase whose synthesis is regulated (according to the action of glutamine) with the participation of glutamine synthetase. NH4+, glutamine and asparagine inhibit also hydrogen photoproduction by purple bacteria and acetylene photoreduction. However, they have no effect on hydrogen evolution in the dark by the cells of R. rubrum and T. roseopersicina in the presence of formiate or pyruvate, respectively, whereas carbon monoxide inhibits hydrogen production. Therefore, hydrogen production by purple bacteria in the dark must be catalyzed by hydrogenase.

Arginine↗
PubMed1976

[Nitrogen metabolism of broilers fed 15-N labeled wheat. 4. 15-N concentration in muscles and nitrogen utilization].

Broilers were fed 15N labelled wheat and the concentration of the labelled isotope in muscular tissue was determined. A negative correlation was found to exist between the percentage proportion of N in the muscle fractions and the level of 15N frequency established 12 hrs after administration of the labelled ration. Higher rates of tracer incorporation were observed in the muscles of legs and other muscles (predominatly red muscles) than in pectoral muscles (white muscles). The heart was shown to exhibit the lowest N content and the highest level of 15N frequency of all muscle fractions. In view of the fact that some specific difficulties will arise when certain factors (trace elements, vitamins, ergotropic substances, genetic factors) which influence the N metabolism of fattening poultry, are estimated on the basis of the conventional N balance trials the present tracer technique is recommended for use as an alternative method in studies of the kind just described. In the present trial 20% of the wheat N were utilized for the production of meat N in muscular tissue.

Animal Feed↗