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Mechthild Tegeder – One of the best experts on this subject based on the ideXlab platform.

  • Role of ureides in source-to-sink transport of photoassimilates in non-fixing soybean
    Journal of Experimental Botany, 2020
    Co-Authors: Sandi Win Thu, Amanda Carter, Ray Collier, Anthony Gandin, Ciera Chenoa Sitton, Mechthild Tegeder
    Abstract:

    Nitrogen (N)-fixing soybean plants use the ureides Allantoin and allantoic acid as major long-distance transport forms of N, but in non-fixing, non-nodulated plants amino acids mainly serve in source-to-sink N allocation. However, some ureides are still synthesized in roots of non-fixing soybean, and our study addresses the role of ureide transport processes in those plants. In previous work, legume ureide permeases (UPSs) were identified that are involved in cellular import of Allantoin and allantoic acid. Here, UPS1 from common bean was expressed in the soybean phloem, which resulted in enhanced source-to-sink transport of ureides in the transgenic plants. This was accompanied by increased ureide synthesis and elevated Allantoin and allantoic acid root-to-sink transport. Interestingly, amino acid assimilation, xylem transport, and phloem partitioning to sinks were also strongly up-regulated. In addition, photosynthesis and sucrose phloem transport were improved in the transgenic plants. These combined changes in source physiology and assimilate partitioning resulted in increased vegetative growth and improved seed numbers. Overall, the results support that ureide transport processes in non-fixing plants affect source N and carbon acquisition and assimilation as well as source-to-sink translocation of N and carbon assimilates with consequences for plant growth and seed development.

  • pvups1 an Allantoin transporter in nodulated roots of french bean
    Plant Physiology, 2004
    Co-Authors: Helene C Pelissier, Marcelo Desimone, Anke Frerich, Karin Schumacher, Mechthild Tegeder
    Abstract:

    Nodulated legumes receive their nitrogen via nitrogen-fixing rhizobia, which exist in a symbiotic relationship with the root system. In tropical legumes like French bean (Phaseolus vulgaris) or soybean (Glycine max), most of the fixed nitrogen is used for synthesis of the ureides Allantoin and allantoic acid, the major long-distance transport forms of organic nitrogen in these species. The purpose of this investigation was to identify a ureide transporter that would allow us to further characterize the mechanisms regulating ureide partitioning in legume roots. A putative Allantoin transporter (PvUPS1) was isolated from nodulated roots of French bean and was functionally characterized in an Allantoin transport-deficient yeast mutant showing that PvUPS1 transports Allantoin but also binds its precursors xanthine and uric acid. In beans, PvUPS1 was expressed throughout the plant body, with strongest expression in nodulated roots, source leaves, pods, and seed coats. In roots, PvUPS1 expression was dependent on the status of nodulation, with highest expression in nodules and roots of nodulated plants compared with non-nodulated roots supplied with ammonium nitrate or Allantoin. In situ RNA hybrhybridization localized PvUPS1 to the nodule endodermis and the endodermis and phloem of the nodule vasculature. These results strengthen our prediction that in bean nodules, PvUPS1 is involved in delivery of Allantoin to the vascular bundle and loading into the nodule phloem.

  • a novel superfamily of transporters for Allantoin and other oxo derivatives of nitrogen heterocyclic compounds in arabidopsis
    The Plant Cell, 2002
    Co-Authors: Marcelo Desimone, Mechthild Tegeder, Elisabetta Catoni, Uwe Ludewig, Melanie Hilpert, Anja Schneider, Reinhard Kunze, Wolf B Frommer, Karin Schumacher
    Abstract:

    A wide spectrum of soil heterocyclic nitrogen compounds are potential nutrients for plants. Here, it is shown that Arabidopsis plants are able to use Allantoin as sole nitrogen source. By functional complementation of a yeast mutant defective in Allantoin uptake, an Arabidopsis transporter, AtUPS1 (Arabidopsis thaliana ureide permease 1), was identified. AtUPS1 belongs to a novel superfamily of plant membrane proteins with five open reading frames in Arabidopsis (identity, 64 to 82%). UPS proteins have 10 putative transmembrane domains with a large cytosolic central domain containing a “Walker A” motif. Transport of (14)C-labeled Allantoin by AtUPS1 in yeast exhibited saturation kinetics (K(m) approximately 52 microM), was dependent on Glc and a proton gradient, and was stimulated by acidic pH. AtUPS1 transports uric acid and xanthine, besides Allantoin, but not adenine. Protons are cosubstrates in Allantoin transport by AtUPS1, as demonstrated by expression in Xenopus laevis oocytes. In plants, AtUPS1 gene expression was dependent on the nitrogen source. Therefore, AtUPS1 presumably is involved in the uptake of Allantoin and other purine degradation products when primary sources are limiting.

D. J. Kyle – One of the best experts on this subject based on the ideXlab platform.

  • Variation between sheep in renal excretion of [14C]Allantoin.
    The British journal of nutrition, 2002
    Co-Authors: P. Prasitkusol, E. R. Ørskov, X. B. Chen, F. D. De B. Hovell, D. J. Kyle
    Abstract:

    The objectives of the present study were to investigate the recovery of [ 14 C]Allantoin in urine of sheep dosed intravenously and degradation of Allantoin by rumen micro-organisms. The recovery of [ 14 C]Allantoin in the urine of eight sheep was measured during three periods in two experiments. Individual values of [ 14 C]Allantoin recovery varied from 66 to 95 % (mean value 83 (SE 1.6) %). The recovery of [ 14 C]Allantoin showed no relation to the level of feed intake. There was some evidence that glomerular filtfiltratione was an important factor affecting the amount of urinary Allantoin recovered in one experiment. Incomplete recovery of plasma [ 14 C]Allantoin in the urine indicated losses of plasma [ 14 C]Allantoin via non-renal routes. This is supported by the disappearance of 14 C from rumen contents incubated in vitro with [ 14 C]Allantoin for 48 h (88 %) and the presence of 14 C in saliva in vivo from sheep sampled after dosing with [ 14 C]Allantoin However, the amount of 14 C activity in the saliva was very low (equivalent to only 1.5 % of the total dose in sheep producing saliva at a rate of 15 litres/d). The proportion of renal and non-renal excretion of purine derivatives was found to be unpredictable both between and within individual animals. The factors responsible for this variability need to be identified, and existing models of excretion of purine derivatives may need to be modified accordingly to improve their accuracy of prediction. A single intravenous injection of [4,5- 14 C]Allantoin provides a simple alternative to infusion methods used to measure the proportion of plasma Allantoin excreted in the urine of sheep. Using this method it may be feasible to validate PD excretion models in other ruminant livestock.

  • determination of 15n isotopic enrichment and concentrations of Allantoin and uric acid in urine by gas chromatography mass spectrometry
    Journal of Mass Spectrometry, 1998
    Co-Authors: X. B. Chen, P. Prasitkusol, D. J. Kyle, Alexander Graham Calder, M C Jayasuriya
    Abstract:

    A method for the determination of 15 N enrichment and concentration of Allantoin and uric acid simultaneously in urine using gas chromatography/mass spectrometry (GC/MS) is described. The urine samples contained [1,3- 15 N 2 ] uric acid and its oxidation product Allantoin. The uric acid and Allantoin were isolated using an AG1-X8 (Cl – form) anion-exchange column and heated with a mixture containing 1:1 dimethylformamide and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA). The tert-butyldimethylsilyl (TBDMS) derivatives of Allantoin and uric acid formed were injected into a gas chromatograph interfaced with a mass spectrometer operated under electron impaimpact ioniionization conditions. Isotope ratio measurements were made from the abundance of the M-57 ions at m/z 398, 399 and 400 for Allantoin and at m/z 567 and 569 for uric acid. 15 N 2 Allantoin (99 at.%) was produced from [1,3- 15 N 2 ] uric acid by treatment with uricase and used as a standard. Quantitation of Allantoin and uric acid was based on isotopic dilution by spiking the urine sample with known quantities of 99 at.% [ 15 N]uric acid and Allantoin internal standards. The observed isotope ratio measurements from the prepared standards matched the theoretical values. Coefficients of variation in measurements of isotope ratio and concentration were 0.2 and 0.5%, respectively. The method was applied in a study to measure the urinary recovery of [1.3- 15 N 2 ]uric acid continuously infused for 8-10 h into the blood of four sheep each on two occasions. Within 24 h, 65.9 ± 9.1% of the tracer was excreted in the urine unchanged. Little was converted into Allantoin (∼7% of the dose). The total recovery (5 days) of the infused tracer averaged 69.5 ± 7.6% as uric acid and 76.8 ± 9.3% as the sum of uric acid and Allantoin. Uricase activities in plasma, liver and kidney of sheep were also measured using [1,3- 15 N 2 ] uric acid as a substrate. Uricase activity was estimated to be 0.6 mU g -1 wet tissue in the liver and there appeared to be none in plasma and kidney. The low uricase activities in sheep tissues appeared to explain the limited conversion of the intravenously administered [ 15 N] uric acid to Allantoin but did not explain the large quantities of Allantoin excreted in urine (8.96±0.86 and 1.36±0.25 mmol d -1 for Allantoin and uric acid, respectively). The GC/MS method for the determination of 15 N enrichment and concentration of Allantoin and uric acid in urine is accurate and precise and provides a useful tool for studies on uric acid and Allantoin metabolism.

  • Renal clearance of plasma Allantoin in sheep
    Experimental physiology, 1991
    Co-Authors: X. B. Chen, D. J. Kyle, E. R. Ørskov, F. D. D. Hovell
    Abstract:

    The recovery in urine of an intrajugular infusion of physiological amounts of Allantoin was measured in four sheep nourished by an intragastric infusion of volatile fattfatty acids and casein (to eliminate rumen fermfermentation). The recovery was 72% (S.E.M. 7) and the remainder was presumed to have been lost by diffusion into the gut and degradation by gut microflora. Measured in two sheep, Allantoin was removed from the blood at a fractional rate of 0.30 h-1, and excreted in urine at 0.23 h-1. Calculation based on creatinine excretion showed glomerular filtfiltratione and tubular reabsorption of Allantoin to be unchanged by the intravenous infusion. Maximal tubular reabsorption at 1.28 mmol day-1 was saturated by the load of endogenous Allantoin alone. In a second experiment with seven normally fed sheep (28-50 kg live weight, all given 1 kg feed), urinary excrexcretion and plasma concentration of Allantoin were linearly related. However, the errors were such that plasma Allantoin concentration would be of little value as a predictor of urinary excrexcretion. There was a nearly twofold range in Allantoin excretion (the larger animals excreting less), which implied that the supply of microbial biomass to the host animal per unit of feed ingested could be profoundly affected by feeding level.

X. B. Chen – One of the best experts on this subject based on the ideXlab platform.

  • Variation between sheep in renal excretion of [14C]Allantoin.
    The British journal of nutrition, 2002
    Co-Authors: P. Prasitkusol, E. R. Ørskov, X. B. Chen, F. D. De B. Hovell, D. J. Kyle
    Abstract:

    The objectives of the present study were to investigate the recovery of [ 14 C]Allantoin in urine of sheep dosed intravenously and degradation of Allantoin by rumen micro-organisms. The recovery of [ 14 C]Allantoin in the urine of eight sheep was measured during three periods in two experiments. Individual values of [ 14 C]Allantoin recovery varied from 66 to 95 % (mean value 83 (SE 1.6) %). The recovery of [ 14 C]Allantoin showed no relation to the level of feed intake. There was some evidence that glomerular filtration rate was an important factor affecting the amount of urinary Allantoin recovered in one experiment. Incomplete recovery of plasma [ 14 C]Allantoin in the urine indicated losses of plasma [ 14 C]Allantoin via non-renal routes. This is supported by the disappearance of 14 C from rumen contents incubated in vitro with [ 14 C]Allantoin for 48 h (88 %) and the presence of 14 C in saliva in vivo from sheep sampled after dosing with [ 14 C]Allantoin However, the amount of 14 C activity in the saliva was very low (equivalent to only 1.5 % of the total dose in sheep producing saliva at a rate of 15 litres/d). The proportion of renal and non-renal excretion of purine derivatives was found to be unpredictable both between and within individual animals. The factors responsible for this variability need to be identified, and existing models of excretion of purine derivatives may need to be modified accordingly to improve their accuracy of prediction. A single intravenous injection of [4,5- 14 C]Allantoin provides a simple alternative to infusion methods used to measure the proportion of plasma Allantoin excreted in the urine of sheep. Using this method it may be feasible to validate PD excretion models in other ruminant livestock.

  • determination of 15n isotopic enrichment and concentrations of Allantoin and uric acid in urine by gas chromatography mass spectrometry
    Journal of Mass Spectrometry, 1998
    Co-Authors: X. B. Chen, P. Prasitkusol, D. J. Kyle, Alexander Graham Calder, M C Jayasuriya
    Abstract:

    A method for the determination of 15 N enrichment and concentration of Allantoin and uric acid simultaneously in urine using gas chromatography/mass spectrometry (GC/MS) is described. The urine samples contained [1,3- 15 N 2 ] uric acid and its oxidation product Allantoin. The uric acid and Allantoin were isolated using an AG1-X8 (Cl – form) anion-exchange column and heated with a mixture containing 1:1 dimethylformamide and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA). The tert-butyldimethylsilyl (TBDMS) derivatives of Allantoin and uric acid formed were injected into a gas chromatograph interfaced with a mass spectrometer operated under electron impact ionization conditions. Isotope ratio measurements were made from the abundance of the M-57 ions at m/z 398, 399 and 400 for Allantoin and at m/z 567 and 569 for uric acid. 15 N 2 Allantoin (99 at.%) was produced from [1,3- 15 N 2 ] uric acid by treatment with uricase and used as a standard. Quantitation of Allantoin and uric acid was based on isotopic dilution by spiking the urine sample with known quantities of 99 at.% [ 15 N]uric acid and Allantoin internal standards. The observed isotope ratio measurements from the prepared standards matched the theoretical values. Coefficients of variation in measurements of isotope ratio and concentration were 0.2 and 0.5%, respectively. The method was applied in a study to measure the urinary recovery of [1.3- 15 N 2 ]uric acid continuously infused for 8-10 h into the blood of four sheep each on two occasions. Within 24 h, 65.9 ± 9.1% of the tracer was excreted in the urine unchanged. Little was converted into Allantoin (∼7% of the dose). The total recovery (5 days) of the infused tracer averaged 69.5 ± 7.6% as uric acid and 76.8 ± 9.3% as the sum of uric acid and Allantoin. Uricase activities in plasma, liver and kidney of sheep were also measured using [1,3- 15 N 2 ] uric acid as a substrate. Uricase activity was estimated to be 0.6 mU g -1 wet tissue in the liver and there appeared to be none in plasma and kidney. The low uricase activities in sheep tissues appeared to explain the limited conversion of the intravenously administered [ 15 N] uric acid to Allantoin but did not explain the large quantities of Allantoin excreted in urine (8.96±0.86 and 1.36±0.25 mmol d -1 for Allantoin and uric acid, respectively). The GC/MS method for the determination of 15 N enrichment and concentration of Allantoin and uric acid in urine is accurate and precise and provides a useful tool for studies on uric acid and Allantoin metabolism.

  • Renal clearance of plasma Allantoin in sheep
    Experimental physiology, 1991
    Co-Authors: X. B. Chen, D. J. Kyle, E. R. Ørskov, F. D. D. Hovell
    Abstract:

    The recovery in urine of an intrajugular infusion of physiological amounts of Allantoin was measured in four sheep nourished by an intragastric infusion of volatile fatty acids and casein (to eliminate rumen fermentation). The recovery was 72% (S.E.M. 7) and the remainder was presumed to have been lost by diffusion into the gut and degradation by gut microflora. Measured in two sheep, Allantoin was removed from the blood at a fractional rate of 0.30 h-1, and excreted in urine at 0.23 h-1. Calculation based on creatinine excretion showed glomerular filtration rate and tubular reabsorption of Allantoin to be unchanged by the intravenous infusion. Maximal tubular reabsorption at 1.28 mmol day-1 was saturated by the load of endogenous Allantoin alone. In a second experiment with seven normally fed sheep (28-50 kg live weight, all given 1 kg feed), urinary excretion and plasma concentration of Allantoin were linearly related. However, the errors were such that plasma Allantoin concentration would be of little value as a predictor of urinary excretion. There was a nearly twofold range in Allantoin excretion (the larger animals excreting less), which implied that the supply of microbial biomass to the host animal per unit of feed ingested could be profoundly affected by feeding level.

Marcelo Desimone – One of the best experts on this subject based on the ideXlab platform.

  • Allantoin accumulation mediated by Allantoinase downregulation and transport by Ureide Permease 5 confers salt stress tolerance to Arabidopsis plants
    Plant Molecular Biology, 2016
    Co-Authors: Carlos Ignacio Lescano, Carolina Martini, Claudio Alejandro González, Marcelo Desimone
    Abstract:

    Allantoin, a metabolite generated in the purine degradation pathway, was primarily considered an intermediate for recycling of the abundant nitrogen assimilated in plant purines. More specifically, tropical legumes utilize Allantoin and allantoic acid as major nodule-to-shoot nitrogen transport compounds. In other species, an increase in Allantoin content was observed under different stress conditions, but the underlying molecular mechanisms remain poorly understood. In this work, Arabidopsis thaliana was used as a model system to investigate the effects of salt stress on Allantoin metabolism and to know whether its accumulation results in plant protection. Plant seedlings treated with NaCl at different concentrations showed higher Allantoin and lower allantoic acid contents. Treatments with NaCl favored the expression of genes involved in Allantoin synthesis, but strongly repressed the unique gene encoding Allantoinase (AtALN). Due to the potential regulatory role of this gene for Allantoin accumulation, AtALN promoter activity was studied using a reporter system. GUS mediated coloration was found in specific plant tissues and was diminished with increasing salt concentrations. Phenotypic analysis of knockout, knockdown and stress-inducible mutants for AtALN revealed that Allantoin accumulation is essential for salt stress tolerance. In addition, the possible role of Allantoin transport was investigated. The Ureide Permease 5 (UPS5) is expressed in the cortex and endodermis of roots and its transcription is enhanced by salt treatment. Ups5 knockout plants under salt stress presented a susceptible phenotype and altered Allantoin root-to-shoot content ratios. Possible roles of Allantoin as a protectant compound in oxidative events or signaling are discussed.

  • pvups1 an Allantoin transporter in nodulated roots of french bean
    Plant Physiology, 2004
    Co-Authors: Helene C Pelissier, Marcelo Desimone, Anke Frerich, Karin Schumacher, Mechthild Tegeder
    Abstract:

    Nodulated legumes receive their nitrogen via nitrogen-fixing rhizobia, which exist in a symbiotic relationship with the root system. In tropical legumes like French bean (Phaseolus vulgaris) or soybean (Glycine max), most of the fixed nitrogen is used for synthesis of the ureides Allantoin and allantoic acid, the major long-distance transport forms of organic nitrogen in these species. The purpose of this investigation was to identify a ureide transporter that would allow us to further characterize the mechanisms regulating ureide partitioning in legume roots. A putative Allantoin transporter (PvUPS1) was isolated from nodulated roots of French bean and was functionally characterized in an Allantoin transport-deficient yeast mutant showing that PvUPS1 transports Allantoin but also binds its precursors xanthine and uric acid. In beans, PvUPS1 was expressed throughout the plant body, with strongest expression in nodulated roots, source leaves, pods, and seed coats. In roots, PvUPS1 expression was dependent on the status of nodulation, with highest expression in nodules and roots of nodulated plants compared with non-nodulated roots supplied with ammonium nitrate or Allantoin. In situ RNA hybridization localized PvUPS1 to the nodule endodermis and the endodermis and phloem of the nodule vasculature. These results strengthen our prediction that in bean nodules, PvUPS1 is involved in delivery of Allantoin to the vascular bundle and loading into the nodule phloem.

  • a novel superfamily of transporters for Allantoin and other oxo derivatives of nitrogen heterocyclic compounds in arabidopsis
    The Plant Cell, 2002
    Co-Authors: Marcelo Desimone, Mechthild Tegeder, Elisabetta Catoni, Uwe Ludewig, Melanie Hilpert, Anja Schneider, Reinhard Kunze, Wolf B Frommer, Karin Schumacher
    Abstract:

    A wide spectrum of soil heterocyclic nitrogen compounds are potential nutrients for plants. Here, it is shown that Arabidopsis plants are able to use Allantoin as sole nitrogen source. By functional complementation of a yeast mutant defective in Allantoin uptake, an Arabidopsis transporter, AtUPS1 (Arabidopsis thaliana ureide permease 1), was identified. AtUPS1 belongs to a novel superfamily of plant membrane proteins with five open reading frames in Arabidopsis (identity, 64 to 82%). UPS proteins have 10 putative transmembrane domains with a large cytosolic central domain containing a “Walker A” motif. Transport of (14)C-labeled Allantoin by AtUPS1 in yeast exhibited saturation kinetics (K(m) approximately 52 microM), was dependent on Glc and a proton gradient, and was stimulated by acidic pH. AtUPS1 transports uric acid and xanthine, besides Allantoin, but not adenine. Protons are cosubstrates in Allantoin transport by AtUPS1, as demonstrated by expression in Xenopus laevis oocytes. In plants, AtUPS1 gene expression was dependent on the nitrogen source. Therefore, AtUPS1 presumably is involved in the uptake of Allantoin and other purine degradation products when primary sources are limiting.

Christopher G Guglielmo – One of the best experts on this subject based on the ideXlab platform.

  • the relationship between uric acid and its oxidative product Allantoin a potential indicator for the evaluation of oxidative stress in birds
    Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2006
    Co-Authors: Ella Tsahar, Christopher G Guglielmo, Zeev Arad, Ido Izhaki
    Abstract:

    Uric acid is the main nitrogenous waste product in birds but it is also known to be a potent antioxidant. Hominoid primates and birds lack the enzyme urate oxidase, which oxidizes uric acid to Allantoin. Consequently, the presence of Allantoin in their plasma results from non-enzymatic oxidation. In humans, the Allantoin to uric acidacid ratio in plasma increases during oxidative stress, thus this ratio has been suggested to be an in vivo marker for oxidative stress in humans. We measured the concentrations of uric acid and Allantoin in the plasma and ureteral urine of white-crowned sparrows (Zonotrichia leucophrys gambelii) at rest, immediately after 30 min of exercise in a hop/hover wheel, and after 1 h of recovery. The plasma Allantoin concentration and the Allantoin to uric acidacid ratio did not increase during exercise but we found a positive relationship between the concentrations of uric acid and Allantoin in the plasma and in the ureteral urine in the three activity phases. In the plasma, the slope of the regression describing the above positive relationships was significantly higher immediately after activity. We suggest that the slope indicates the rate of uric acid oxidation and that during activity this rate increases as a result of higher production of free radicals. The present study demonstrates that Allantoin is present in the plasma and in the ureteral urine of white-crowned sparrows and therefore might be useful as an indicator of oxidative stress in birds.