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Sample records for ecosystem 15n labeling

  1. Nitrogen processing in a tidal freshwater marsh: a whole ecosystem 15N labeling study

    DEFF Research Database (Denmark)

    Gribsholt, B.; Boschker, H.T.S.; Struyf, E.

    2005-01-01

    We quantified the fate and transport of watershed-derived ammonium in a tidal freshwater marsh fringing the nutrient-rich Scheldt River in a whole-ecosystem 15N labeling experiment. 15N-NH4+ was added to the floodwater entering a 3,477 m2 tidal marsh area, and marsh ammonium processing...... and retention were traced in six subsequent tide cycles. We present data for the water phase components of the marsh system, in which changes in concentration and isotopic enrichment of NO3-, NO2- , N2O, N2, NH4+, and suspended particulate nitrogen (SPN) were measured in concert with a mass balance study......, with nitrification accounting for 30% of 15N-transformation. In situ whole-ecosystem nitrification rates were four to nine times higher than those in the water column alone, implying a crucial role for the large reactive marsh surface area in N-transformation. Under conditions of low oxygen concentrations and high...

  2. The fate of 13C15N labelled glycine in permafrost and surface soil at simulated thaw in mesocosms from high arctic and subarctic ecosystems

    DEFF Research Database (Denmark)

    Ravn, Nynne Marie Rand; Elberling, Bo; Michelsen, Anders

    2017-01-01

    glycine addition. Results: Near-surface soil microbes were more efficient in the uptake of intact glycine immediately upon thaw than plants. After one month plants had gained more 15N whereas microbes seemed to lose 15N originating from glycine. We observed a time lag in glycine degradation upon...... compound in thawing permafrost and surface soil. Methods: Double labeled glycine (13C15N) was added to soil columns with vegetation and to permafrost. During thaw conditions ecosystem respiration 13C was measured and 13C and 15N distribution in the ecosystem pools was quantified one day and one month after...... permafrost thaw, in contrast to surface soil thaw. Conclusions: Our results suggest that both arctic plants and microorganisms acquire amino acids released upon spring and permafrost thaw. Despite indications of more efficient utilization of added substrate in the High Arctic than the Subarctic, we conclude...

  3. Synthesis of {sup 15}N-labeled phthalimide

    Energy Technology Data Exchange (ETDEWEB)

    Liu Zhanfeng [College of Life Science and Technology, Beijing University of Chemical Technology, P.O. Box 75, Beijing, 100029 (China); Yuan Qipeng [College of Life Science and Technology, Beijing University of Chemical Technology, P.O. Box 75, Beijing, 100029 (China)]. E-mail: yuanqp@mail.buct.edu.cn

    2006-07-15

    A new method for preparing {sup 15}N-labeled phthalimide from the reaction between phthalic anhydride and {sup 15}N-urea (99.34%{sup 15}N) in the presence of ortho-xylene is described in this work. Reaction conditions were the mole ratio of phthalic anhydride to {sup 15}N-urea (99.34%{sup 15}N) of 3-1 at 140 {sup o}C and under atmospheric pressure. Excessive phthalic anhydride reacted with ethanol for 90 min. The by-product of diethyl phthalate dissolving in ethanol was separated by filtration. The high yield of 96% of {sup 15}N-labeled phthalimide was obtained and the purity and abundance was 99.5% and 99.04%, respectively.

  4. Synthesis of {sup 15}N labeled glyphosate; Sintese do glifosato enriquecido com {sup 15}N

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Claudineia R. de; Bendassolli, Jose Albertino; Tavares, Glauco Arnold; Rossete, Alexssandra L.R.M.; Tagliassachi, Romulo Barbieri; Prestes, Cleuber Vieira [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Dept. de Isotopos Estaveis]. E-mail: crolivei@cena.usp.br

    2005-07-01

    Amongst the actually commercialized herbicides the Glyphosate is the most used in Brazil. Its efficiency as well as the others herbicides against undesirable weeds is harmed by its final composts left at the environment. Although studies has being carried out to improve the knowledge about the herbicides behavior at the environment its complexity has led them towards innumerous to new significant research work where the use of radiolabeled composts (radiative tracers) are recommended to evaluate their bio-availability in the soil. However is the use, the manipulation and the storage of radiolabeled composts is requires an extra care under chemical safety point of view. The use of non radiolabeled composts is a world tendency especially for field researches. Under this context the presented work describes a method for the synthesis of {sup 15}N labeled glyphosate. The {sup 15}N-herbicide was undertaken by phosphometilation with the phosphit dialquil and {sup 15}N-glycine. The tests where carried out through a micro scale production plant and of equimolars amounts. At these conditions it's was possible to reach approximately a 20% of yield. At the conclusion of a best operational condition its expected to offer another important toll that shall be used in glyphosate behavior at the environment and undesirably weeds. (author)

  5. Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh - a whole ecosystem 15N enrichment study

    NARCIS (Netherlands)

    Gribsholt, B.; Struyf, E.; Tramper, A.; de Brabandere, L.; Brion, N.; van Damme, S.; Meire, P.; Dehairs, F.; Middelburg, J.J.; Boschker, H.T.S.

    2007-01-01

    An intact tidal freshwater marsh system (3477 m2) was labelled by adding 15N-ammonium as a tracer to the flood water inundating the ecosystem. The appearance and retention of 15N-label in different marsh components (leaves, roots, sediment, leaf litter and invertebrate fauna) was followed over 15

  6. Fate of orally administered {sup 15}N-labeled polyamines in rats bearing solid tumors

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Masaki; Samejima, Keijiro; Goda, Hitomi; Niitsu, Masaru [Josai Univ., Sakado, Saitama (Japan). Faculty of Pharmaceutical Sciences; Xu Yongji [Qingdao Univ. of Science and Technology (China). Inst. of Chemical and Molecular Technology; Takahashi, Masakazu [Sasaki Inst., Tokyo (Japan); Hashimoto, Yoshiyuki [Kyoritsu Coll. of Pharmacy, Tokyo (Japan)

    2003-03-01

    We studied absorption, distribution, metabolism, and excretion of polyamines (putrescine, spermidine, and spermine) in the gastrointestinal tract using {sup 15}N-labeled polyamines as tracers and ionspray ionization mass spectrometry (IS-MS). The relatively simple protocol using rats bearing solid tumors provided useful information. Three {sup 15}N-labeled polyamines that were simultaneously administered were absorbed equally from gastrointestinal tract, and distributed within tissues at various concentrations. The uptake of {sup 15}N-spermidine seemed preferential to that of {sup 15}N-spermine since the concentrations of {sup 15}N-spermidine in the liver and tumors were higher, whereas those of {sup 15}N-spermine were higher in the kidney, probably due to the excretion of excess extracellular spermine. Most of the absorbed {sup 15}N-putrescine seemed to be lost, suggesting blood and tissue diamine oxidase degradation. Concentrations of {sup 15}N-spermidine and {sup 15}N-spermine in the tumor were low. We also describe the findings from two rats that were administered with {sup 15}N-spermine. The tissue concentrations of {sup 15}N-spermine were unusually high, and significant levels of {sup 15}N-spermidine were derived from {sup 15}N-spermine in these animals. (author)

  7. Labelling of animal manure nitrogen with 15N

    DEFF Research Database (Denmark)

    Sørensen, P.; Jensen, E.S.; Nielsen, N.E.

    1994-01-01

    A sheep was fed on N-15-labelled ryegrass hay during a period of 9 days in order to obtain N-15-labelled manure. After 9 days of feeding, the total N in faeces contained 3.70 atom % N-15 excess, which was equivalent to 82% of the N-15 enrichment of the hay N. The easily-decomposable fraction...... of the faecal N was less labelled (2.89 atom % N-15 excess) than the slowly-decomposable fraction. The N-15 enrichment of mineralized faecal N did not change significantly during 32 weeks of incubation in sand. About 25% of the faecal N was water-soluble. This N had a higher N-15 enrichment than the total...... faecal N, indicating that a part of the water-soluble N was indigestible feed N. The faeces contained only small amounts of NH4+-N, which had a N-15 enrichment similar to the N-15 enrichment of N mineralized during incubation in sand. It is suggested that the labelled faecal N obtained after a few days...

  8. The contamination of commercial 15N2 gas stocks with 15N-labeled nitrate and ammonium and consequences for nitrogen fixation measurements.

    Directory of Open Access Journals (Sweden)

    Richard Dabundo

    Full Text Available We report on the contamination of commercial 15-nitrogen (15N N2 gas stocks with 15N-enriched ammonium, nitrate and/or nitrite, and nitrous oxide. 15N2 gas is used to estimate N2 fixation rates from incubations of environmental samples by monitoring the incorporation of isotopically labeled 15N2 into organic matter. However, the microbial assimilation of bioavailable 15N-labeled N2 gas contaminants, nitrate, nitrite, and ammonium, is liable to lead to the inflation or false detection of N2 fixation rates. 15N2 gas procured from three major suppliers was analyzed for the presence of these 15N-contaminants. Substantial concentrations of 15N-contaminants were detected in four Sigma-Aldrich 15N2 lecture bottles from two discrete batch syntheses. Per mole of 15N2 gas, 34 to 1900 µmoles of 15N-ammonium, 1.8 to 420 µmoles of 15N-nitrate/nitrite, and ≥21 µmoles of 15N-nitrous oxide were detected. One 15N2 lecture bottle from Campro Scientific contained ≥11 µmoles of 15N-nitrous oxide per mole of 15N2 gas, and no detected 15N-nitrate/nitrite at the given experimental 15N2 tracer dilutions. Two Cambridge Isotopes lecture bottles from discrete batch syntheses contained ≥0.81 µmoles 15N-nitrous oxide per mole 15N2, and trace concentrations of 15N-ammonium and 15N-nitrate/nitrite. 15N2 gas equilibrated cultures of the green algae Dunaliella tertiolecta confirmed that the 15N-contaminants are assimilable. A finite-differencing model parameterized using oceanic field conditions typical of N2 fixation assays suggests that the degree of detected 15N-ammonium contamination could yield inferred N2 fixation rates ranging from undetectable, <0.01 nmoles N L(-1 d(-1, to 530 nmoles N L(-1 d(-1, contingent on experimental conditions. These rates are comparable to, or greater than, N2 fixation rates commonly detected in field assays. These results indicate that past reports of N2 fixation should be interpreted with caution, and demonstrate that the purity of

  9. 15N-labelling and preliminary heteronuclear NMR study of Desulfovibrio vulgaris Hildenborough cytochrome c553.

    Science.gov (United States)

    Morelli, X; Dolla, A; Toci, R; Guerlesquin, F

    1999-04-01

    When using heteronuclear NMR, 15N-labelling is necessary for structural analysis, dynamic studies and determination of complex formation. The problems that arise with isotopic labelling of metalloproteins are due to their complex maturation process, which involves a large number of factors. Cytochromes c are poorly expressed in Escherichia coli and the overexpression that is necessary for 15N-labelling, requires an investigation of the expression host and special attention to growth conditions. We have succeeded in the heterologous expression and the complete and uniform isotopic 15N-labelling of the cytochrome c553 from Desulfovibrio vulgaris Hildenborough, in a sulphate-reducing bacterium, D. desulfuricans G200, by using a growth medium combining 15N-ammonium chloride and 15N-Celtone. These conditions allowed us to obtain approximately 0.8 mg x L-1 of pure labelled cytochrome c553. 1H and 15N-assignments for both the oxidized and the reduced states of cytochrome c553 were obtained from two-dimensional heteronuclear experiments. Pseudocontact effects due to the haem Fe3+ have been analysed for the first time through 15N and 1H chemical shifts in a c-type cytochrome.

  10. Optimizing identification and quantitation of 15N-labeled proteins in comparative proteomics.

    Science.gov (United States)

    Gouw, Joost W; Tops, Bastiaan B J; Mortensen, Peter; Heck, Albert J R; Krijgsveld, Jeroen

    2008-10-15

    Comparative proteomics has emerged as a powerful approach to determine differences in protein abundance between biological samples. The introduction of stable-isotopes as internal standards especially paved the road for quantitative proteomics for comprehensive approaches to accurately determine protein dynamics. Metabolic labeling with (15)N isotopes is applied to an increasing number of organisms, including Drosophila, C. elegans, and rats. However, (15)N-enrichment is often suboptimal (quantitation of proteins. Here, we systematically investigated two independent (15)N-labeled data sets to explore the influence of heavy nitrogen enrichment on the number of identifications as well as on the error in protein quantitation. We show that specifically larger (15)N-labeled peptides are under-represented when compared to their (14)N counterparts and propose a correction method, which significantly increases the number of identifications. In addition, we developed a method that corrects for inaccurate peptide ratios introduced by incomplete (15)N enrichment. This results in improved accuracy and precision of protein quantitation. Altogether, this study provides insight into the process of protein identification and quantitation, and the methods described here can be used to improve both qualitative and quantitative data obtained by labeling with heavy nitrogen with enrichment less than 100%.

  11. Dynamics of N2O production pathways analyzed by 15N18O isotope labeling

    DEFF Research Database (Denmark)

    Jensen, Marlene Mark; Ma, Chun; Lavik, Gaute

    Nitrous oxide production associated with biological nitrogen transformations can contribute substantially to the CO2 footprint of both man-made and natural systems, but the pathways and regulation of N2O production are poorly understood. We developed a 15N/18O dual isotope labelling technique...... demonstrate three active pathways of N2O production, each with different environmental controls. The dual 15N/18O isotope labelling approach can contribute to the development of strategies to minimise N2O emissions from man-made and natural systems....

  12. Production of 15N-labeled α-amanitin in Galerina marginata

    Science.gov (United States)

    DuBois, Brandon; Sgambelluri, R. Michael; Angelos, Evan R.; Li, Xuan; Holmes, Daniel

    2015-01-01

    α-Amanitin is the major causal constituent of deadly Amanita mushrooms that account for the majority of fatal mushroom poisonings worldwide. It is also an important biochemical tool for the study of its target, RNA polymerase II. The commercial supply of this bicyclic peptide comes directly from A. phalloides, the death cap mushroom, which is collected from its natural habitat. Isotopically labeled amanitin could be useful for clinical and forensic applications, but α-amanitin has not been chemically synthesized and A. phalloides cannot be cultured on artificial medium. Using Galerina marginata, an unrelated saprobic mushroom that grows and produces α-amanitin in culture, we describe a method for producing 15N-labeled α-amanitin using growth media containing 15N as sole nitrogen source. A key to success was preparing 15N-enriched yeast extract via a novel method designated “glass bead-assisted maturation.” In the presence of the labeled yeast extract and 15N-NH4Cl, α-amanitin was produced with >97% isotope enrichment. The labeled product was confirmed by HPLC, high-resolution mass spectrometry, and NMR. PMID:26100667

  13. Studies with /sup 15/N-labelled lysine in colostomized laying hens. 5. /sup 15/N incorporation into blood fractions and gastrointestinal tract

    Energy Technology Data Exchange (ETDEWEB)

    Gruhn, K.; Hennig, A.; Graf, H. (Karl-Marx-Universitaet, Leipzig (German Democratic Republic). Sektion Tierproduktion und Veterinaermedizin)

    1984-08-01

    3 colostomized laying hens received, together with a commercial ration of 120 g, 0.2 % /sup 15/N-labelled L-lysine with an atom-% /sup 15/N excess (/sup 15/N') of 48 %; subsequently the same ration was fed over a period of 4 days with 0.2 % unlabelled L-lysine. After the end of the experiment the hens were slaughtered. The atom-% /sup 15/N' was determined in total, in the lysine, histidine and arginine N of blood cells, plasma, NPN fraction of the blood, stomach, small intestine, cecum and rectum. /sup 15/N' in the blood cells was 0.11 atom-% in the blood plasma 0.17 atom-%, in the NPN fraction of the blood 0.09 atom-%, in the tissues of the gastrointestinal tract 0.11 atom-% and in its contents 0.12 atom-%. On the average the blood contained per hen 77.9 % lysine-/sup 15/N', 16.4 % arginine-/sup 15/N' and 5.7 % histidine-/sup 15/N' of the basic amino acid-/sup 15/N'. For the gastrointestinal tract 78.7 % lysine-/sup 15/N', 19.0 % arginine-/sup 15/N' and 2.3 % histidine-/sup 15/N' of the /sup 15/N' of the basic amino acids were ascertained. In comparison to histidine the ..cap alpha..-amino-N of lysine is incorporated to a considerably higher degree into arginine. For lysine and arginine the atom-% /sup 15/N' in the contents of the gastrointestinal tract is 4 days after the end of the supplementation of labelled lysine 8 to 10 times higher than in the feces of the last day of the experiment. This indicates a considerable secretion of the 2 amino acids in the gastrointestinal tract and their reabsorption to a large extent.

  14. Nitrogen turnover of three different agricultural soils determined by 15N triple labelling

    Science.gov (United States)

    Fiedler, Sebastian R.; Kleineidam, Kristina; Strasilla, Nicol; Schlüter, Steffen; Reent Köster, Jan; Well, Reinhard; Müller, Christoph; Wrage-Mönnig, Nicole

    2017-04-01

    To meet the demand for data to improve existing N turnover models and to evaluate the effect of different soil physical properties on gross nitrogen (N) transformation rates, we investigated two arable soils and a grassland soil after addition of ammonium nitrate (NH4NO3), where either ammonium (NH4+), or nitrate (NO3-), or both pools have been labelled with 15N at 60 atom% excess (triple 15N tracing method). Besides NH4+, NO3- and nitrite (NO2-) contents with their respective 15N enrichment, nitrous oxide (N2O) and dinitrogen (N2) fluxes have been determined. Each soil was adjusted to 60 % of maximum water holding capacity and pre-incubated at 20˚ C for two weeks. After application of the differently labelled N fertilizer, the soils were further incubated at 20˚ C under aerobic conditions in a He-N2-O2 atmosphere (21 % O2, 76 He, 2% N2) to increase the sensitivity of N2 rates via the 15N gas flux method. Over a 2 week period soil N pools were quantified by 2 M KCl extraction (adjusted to pH 7 to prevent nitrite losses) (Stevens and Laughlin, 1995) and N gas fluxes were measured by gas chromatography in combination with IRMS. Here, we present the pool sizes and fluxes as well as the 15N enrichments during the study. Results are discussed in light of the soil differences that were responsible for the difference in gross N dynamics quantified by the 15N tracing model Ntrace (Müller et al., 2007). References Müller, C., T. Rütting, J. Kattge, R.J. Laughlin, and R.J. Stevens, (2007) Estimation of parameters in complex 15N tracing models by Monte Carlo sampling. Soil Biology & Biochemistry. 39(3): p. 715-726. Stevens, R.J. and R.J. Laughlin, (1995) Nitrite transformations during soil extraction with potassium chloride. Soil Science Society of America Journal. 59(3): p. 933-938.

  15. Assessment of net postprandial protein utilization of 15N-labelled milk nitrogen in human subjects.

    Science.gov (United States)

    Bos, C; Mahé, S; Gaudichon, C; Benamouzig, R; Gausserès, N; Luengo, C; Ferrière, F; Rautureau, J; Tomé, D

    1999-03-01

    The nutritional quality of milk proteins, evaluated both in terms of digestibility and postprandial oxidation and retention in human subjects, was investigated in this study. Five healthy adult volunteers were given 480 ml 15N-labelled milk (i.e. 190 mmol N). 15N was subsequently determined at the ileal level, using a naso-intestinal intubation technique, as well as at the faecal level. Plasma and urine were sampled for 8 h after meal ingestion. Dietary exogenous N recovered at the terminal ileum after 8 h reached 8.6 (SE 0.8) mmol while the amount collected in the faeces was 6.5 (SE 0.7) mmol after 5 d. The true ileal and faecal digestibilities were 95.5 (SE 0.4)% and 96.6 (SE 0.4)% respectively. The appearance of [15N]amino acids in the plasma was rapid and prolonged. The measurement of 15N in the body urea pool and in the N excreted in the urine allowed us to calculate the deamination occurring after [15N]milk protein absorption. The net postprandial protein utilization (i.e. NPPU = (Nabsorbed-Ndeaminated)/Ningested), calculated as an index of protein quality 8 h after milk ingestion, was 81.0 (SE 1.9)%. Our data confirm that milk protein has a high oro-ileal digestibility in man and demonstrate that milk protein has a high NPPU, an index corresponding to a period in which the dietary protein retention is maximal.

  16. Compound-specific δ15N amino acid measurements in littoral mussels in the California upwelling ecosystem: a new approach to generating baseline δ15N Isoscapes for coastal ecosystems.

    Directory of Open Access Journals (Sweden)

    Natasha L Vokhshoori

    Full Text Available We explored δ(15N compound-specific amino acid isotope data (CSI-AA in filter-feeding intertidal mussels (Mytilus californianus as a new approach to construct integrated isoscapes of coastal primary production. We examined spatial δ(15N gradients in the California Upwelling Ecosystem (CUE, determining bulk δ(15N values of mussel tissue from 28 sites between Port Orford, Oregon and La Jolla, California, and applying CSI-AA at selected sites to decouple trophic effects from isotopic values at the base of the food web. Bulk δ(15N values showed a strong linear trend with latitude, increasing from North to South (from ∼ 7‰ to ∼ 12‰, R(2 = 0.759. In contrast, CSI-AA trophic position estimates showed no correlation with latitude. The δ(15N trend is therefore most consistent with a baseline δ(15N gradient, likely due to the mixing of two source waters: low δ(15N nitrate from the southward flowing surface California Current, and the northward transport of the California Undercurrent (CUC, with (15N-enriched nitrate. This interpretation is strongly supported by a similar linear gradient in δ(15N values of phenylalanine (δ(15NPhe, the best AA proxy for baseline δ(15N values. We hypothesize δ(15N(Phe values in intertidal mussels can approximate annual integrated δ(15N values of coastal phytoplankton primary production. We therefore used δ(15N(Phe values to generate the first compound-specific nitrogen isoscape for the coastal Northeast Pacific, which indicates a remarkably linear gradient in coastal primary production δ(15N values. We propose that δ(15N(Phe isoscapes derived from filter feeders can directly characterize baseline δ(15N values across major biochemical provinces, with potential applications for understanding migratory and feeding patterns of top predators, monitoring effects of climate change, and study of paleo- archives.

  17. Rapid mass spectrometric analysis of 15N-Leu incorporation fidelity during preparation of specifically labeled NMR samples

    DEFF Research Database (Denmark)

    Truhlar, Stephanie M E; Cervantes, Carla F; Torpey, Justin W

    2008-01-01

    . MALDI TOF-TOF MS/MS data provide additional information that shows where the "extra" (15)N labels are incorporated, which can be useful in confirming ambiguous assignments. The described procedure provides a rapid technique to monitor the fidelity of selective labeling that does not require a lot......Advances in NMR spectroscopy have enabled the study of larger proteins that typically have significant overlap in their spectra. Specific (15)N-amino acid incorporation is a powerful tool for reducing spectral overlap and attaining reliable sequential assignments. However, scrambling of the label...... during protein expression is a common problem. We describe a rapid method to evaluate the fidelity of specific (15)N-amino acid incorporation. The selectively labeled protein is proteolyzed, and the resulting peptides are analyzed using MALDI mass spectrometry. The (15)N incorporation is determined...

  18. Soil NO3-δ15N compositions of plant-soil ecosystems on the Chinese Loess Plateau

    Science.gov (United States)

    Liu, J.; Liu, W.

    2015-12-01

    Soil NO3-δ15N values are extremely valuable for understanding nutrient biogeochemical cycling in plant-soil ecosystems. Here, we investigated the δ15N values of surface bulk soil, soil NO3 and plants from six restoration grasslands in two different regions (Yunwu Mountain and Bin County) of the Chinese Loess Plateau to study soil NO3 conversion and transportation in these ecosystems. The soil NO3-δ15N values of Yunwu Mountain ranged from -0.1‰ to 1.3‰, and the soil NO3-δ15N values of Bin County ranged from 1.2‰ to 11.3‰. In our result, (1) the soil NO3-δ15N values increased as plant δ15N values decreased in study areas. Additionally, the bulk soil δ15N values were positively correlated with plant δ15N values. (2) In both study areas, the soil NO3-δ15N values were positively correlated with soil water content. In contrast, the bulk soil δ15N and plant δ15N values were negatively correlated with increasing soil water content. It is shown that soil NO3 is easily absorbed by plants in our study areas, which indicates that NO3 is the primary inorganic N source for grassland plants on the Chinese Loess Plateau. The plants absorbed more 15N-depleted NO3 when soil water content increased. Fallen litter assimilated by the soil produced the positive correlation between bulk soil δ15N values and plant δ15N values, which may explain how the plant-soil N cycle responds to soil water changes and may explain the negative correlation between bulk soil δ15N values and mean annual precipitation.

  19. Rapid mass spectrometric analysis of 15N-Leu incorporation fidelity during preparation of specifically labeled NMR samples.

    Science.gov (United States)

    Truhlar, Stephanie M E; Cervantes, Carla F; Torpey, Justin W; Kjaergaard, Magnus; Komives, Elizabeth A

    2008-09-01

    Advances in NMR spectroscopy have enabled the study of larger proteins that typically have significant overlap in their spectra. Specific (15)N-amino acid incorporation is a powerful tool for reducing spectral overlap and attaining reliable sequential assignments. However, scrambling of the label during protein expression is a common problem. We describe a rapid method to evaluate the fidelity of specific (15)N-amino acid incorporation. The selectively labeled protein is proteolyzed, and the resulting peptides are analyzed using MALDI mass spectrometry. The (15)N incorporation is determined by analyzing the isotopic abundance of the peptides in the mass spectra using the program DEX. This analysis determined that expression with a 10-fold excess of unlabeled amino acids relative to the (15)N-amino acid prevents the scrambling of the (15)N label that is observed when equimolar amounts are used. MALDI TOF-TOF MS/MS data provide additional information that shows where the "extra" (15)N labels are incorporated, which can be useful in confirming ambiguous assignments. The described procedure provides a rapid technique to monitor the fidelity of selective labeling that does not require a lot of protein. These advantages make it an ideal way of determining optimal expression conditions for selectively labeled NMR samples.

  20. Synthesis and characterization of a [3-15N]-labeled cis-syn thymine dimer-containing DNA duplex.

    Science.gov (United States)

    Bdour, Hussam M; Kao, Jeff Lung-Fa; Taylor, John-Stephen

    2006-02-17

    Cis-syn thymine dimers are the major photoproducts of DNA and are the principal cause of mutations induced by sunlight. To better understand the nature of base pairing with cis-syn thymine dimers, we have synthesized a decamer oligodeoxynucleotide (ODN) containing a cis-syn thymine dimer labeled at the N3 of both T's with 15N by two efficient routes from [3-15N]-thymidine phosphoramidite. In the postsynthetic irradiation route, an ODN containing an adjacent pair of [3-15N]-labeled T's was irradiated and the cis-syn dimer-containing ODN isolated by HPLC. In the mixed building block route, a mixture of cis-syn and trans-syn dimer-containing ODNs was synthesized from a mixture of [3-15N]-labeled thymine dimer phosphoramidites after which the cis-syn dimer-containing ODN was isolated by HPLC. The N3-nitrogen and imino proton signals of an (15)N-labeled thymine dimer-containing decamer duplex were assigned by 2D 1H-15N heterocorrelated HSQC NMR spectroscopy, and the 15N-1H coupling constant was found to be 1.8 Hz greater for the 5'-T than for the 3'-T. The larger coupling constant is indicative of weaker H-bonding that is consistent with the more distorted nature of the 5'-base pair found in solution state NMR and crystallographic structures.

  1. Tandem mass spectrometric investigation of acylpolyamines of spider venoms and their 15N-labeled derivatives.

    Science.gov (United States)

    Tzouros, Manuel; Manov, Nikolay; Bienz, Stefan; Bigler, Laurent

    2004-11-01

    The fragmentation mechanism of the acylpentamine toxins 1-4 found in the venom of the spider Agelenopsis aperta has been investigated in detail. To identify the origin of the two doublets of unexpected fragment ions at m/z 129/112 and m/z 115/98, three synthetic 15N-labeled analogs 5-7 have been prepared and subjected to CID fragmentation on a triple quadrupole mass spectrometer. It appears that the unexpected doublet of fragment ions arises from an internal portion of the polyamine backbone after either a transaminative Zip reaction or a sequential fragmentation of the quasi-molecular ion. The second option has been proven by in-source CID experiments. The detailed knowledge of acylpentamine fragmentation mechanisms is essential for the correct characterization of isomeric compounds, particularly for coeluting compounds within complex mixtures such as spider venoms.

  2. The synthesis of 15N(7)-Hoogsteen face-labeled adenosine phosphoramidite for solid-phase RNA synthesis.

    Science.gov (United States)

    Neuner, Sandro; Kreutz, Christoph; Micura, Ronald

    2017-01-01

    We have developed an efficient route for the synthesis of 15N(7)-labeled adenosine as phosphoramidite building block for site- and atom-specific incorporation into RNA by automated solid-phase synthesis. Such labeled RNA is required for the evaluation of selected non-canonical base pair interactions in folded RNA using NMR spectroscopic methods.

  3. Decomposition and nitrogen dynamics of 15N-labeled leaf, root, and twig litter in temperate coniferous forests

    Science.gov (United States)

    van Huysen, Tiff L.; Harmon, Mark E.; Perakis, Steven S.; Chen, Hua

    2013-01-01

    Litter nutrient dynamics contribute significantly to biogeochemical cycling in forest ecosystems. We examined how site environment and initial substrate quality influence decomposition and nitrogen (N) dynamics of multiple litter types. A 2.5-year decomposition study was installed in the Oregon Coast Range and West Cascades using 15N-labeled litter from Acer macrophyllum, Picea sitchensis, and Pseudotsuga menziesii. Mass loss for leaf litter was similar between the two sites, while root and twig litter exhibited greater mass loss in the Coast Range. Mass loss was greatest from leaves and roots, and species differences in mass loss were more prominent in the Coast Range. All litter types and species mineralized N early in the decomposition process; only A. macrophyllum leaves exhibited a net N immobilization phase. There were no site differences with respect to litter N dynamics despite differences in site N availability, and litter N mineralization patterns were species-specific. For multiple litter × species combinations, the difference between gross and net N mineralization was significant, and gross mineralization was 7–20 % greater than net mineralization. The mineralization results suggest that initial litter chemistry may be an important driver of litter N dynamics. Our study demonstrates that greater amounts of N are cycling through these systems than may be quantified by only measuring net mineralization and challenges current leaf-based biogeochemical theory regarding patterns of N immobilization and mineralization.

  4. Unusually negative nitrogen isotopic compositions (δ15N of mangroves and lichens in an oligotrophic, microbially-influenced ecosystem

    Directory of Open Access Journals (Sweden)

    I. Romero

    2008-12-01

    Full Text Available Extremes in δ15N values in mangrove tissues and lichens (range =+4 to −22‰ were measured from a mangrove forest ecosystem located on Twin Cays, offshore islands in Belize, Central America. The N isotopic compositions and concentrations of NH4+/NH3 in porewater, rainwater, and atmospheric ammonia, and the δ15N of lichens, mangrove leaves, roots, stems, and wood were examined to study the biogeochemical processes important for establishing these unusual N isotopic ratios. Dwarfed Rhizophora mangle trees had the most negative δ15N, whereas fringing Rhizophora trees, the most positive δ15N values. Porewater ammonium concentrations had little relationship to N isotopic fractionation in mangrove tissues. In dwarfed mangroves, the δ15N of fine and coarse roots were 6–9‰ more positive than leaf tissue from the same tree, indicating different sources of N for root and leaf tissues. When P was added to dwarfed mangrove trees without added N, δ15N increased within one year from −12‰ to −2‰, approaching the δ15N of porewater ammonium (δ15N=+4‰. Isotopically depleted ammonia in the atmosphere (δ15N=−19‰ and in rainwater (δ15N=−10‰ were found on Twin Cays. We propose that foliar uptake of these atmospheric sources by P-stressed, dwarfed mangrove trees and lichens can explain their very negative δ15N values. In environments where P is limiting for growth, uptake of atmospheric N by Rhizophora mangle may be an important adaptive strategy.

  5. Unusually negative nitrogen isotopic compositions (δ15N) of mangroves and lichens in an oligotrophic, microbially-influenced ecosystem

    Science.gov (United States)

    Fogel, M. L.; Wooller, M. J.; Cheeseman, J.; Smallwood, B. J.; Roberts, Q.; Romero, I.; Meyers, M. J.

    2008-12-01

    Extremes in δ15N values in mangrove tissues and lichens (range =+4 to -22‰) were measured from a mangrove forest ecosystem located on Twin Cays, offshore islands in Belize, Central America. The N isotopic compositions and concentrations of NH4+/NH3 in porewater, rainwater, and atmospheric ammonia, and the δ15N of lichens, mangrove leaves, roots, stems, and wood were examined to study the biogeochemical processes important for establishing these unusual N isotopic ratios. Dwarfed Rhizophora mangle trees had the most negative δ15N, whereas fringing Rhizophora trees, the most positive δ15N values. Porewater ammonium concentrations had little relationship to N isotopic fractionation in mangrove tissues. In dwarfed mangroves, the δ15N of fine and coarse roots were 6-9‰ more positive than leaf tissue from the same tree, indicating different sources of N for root and leaf tissues. When P was added to dwarfed mangrove trees without added N, δ15N increased within one year from -12‰ to -2‰, approaching the δ15N of porewater ammonium (δ15N=+4‰). Isotopically depleted ammonia in the atmosphere (δ15N=-19‰) and in rainwater (δ15N=-10‰) were found on Twin Cays. We propose that foliar uptake of these atmospheric sources by P-stressed, dwarfed mangrove trees and lichens can explain their very negative δ15N values. In environments where P is limiting for growth, uptake of atmospheric N by Rhizophora mangle may be an important adaptive strategy.

  6. Solid state NMR studies of oligourea foldamers: interaction of 15N-labelled amphiphilic helices with oriented lipid membranes.

    Science.gov (United States)

    Aisenbrey, Christopher; Pendem, Nagendar; Guichard, Gilles; Bechinger, Burkhard

    2012-02-21

    Synthetic oligomers that are derived from natural polypeptide sequences, albeit with unnatural building blocks, have attracted considerable interest in mimicking bioactive peptides and proteins. Many of those compounds adopt stable folds in aqueous environments that resemble protein structural elements. Here we have chemically prepared aliphatic oligoureas and labeled them at selected positions with (15)N for structural investigations using solid-state NMR spectroscopy. In the first step, the main tensor elements and the molecular alignment of the (15)N chemical shift tensor were analyzed. This was possible by using a two-dimensional heteronuclear chemical shift/dipolar coupling correlation experiment on a model compound that represents the chemical, and thereby also the chemical shift characteristics, of the urea bond. In the next step (15)N labeled versions of an amphipathic oligourea, that exert potent antimicrobial activities and that adopt stable helical structures in aqueous environments, were prepared. These compounds were reconstituted into oriented phospholipid bilayers and the (15)N chemical shift and (1)H-(15)N dipolar couplings of two labeled sites were determined by solid-state NMR spectroscopy. The data are indicative of an alignment of this helix parallel to the membrane surface in excellent agreement with the amphipathic character of the foldamer and consistent with previous models explaining the antimicrobial activities of α-peptides.

  7. The effects of isotope-labeled analogs on the LC-IDMS measurement by comparison of ESI responses and matrix effect of melamine, 13C3-melamine, 13C3+15N3-melamine, and 15N3-melamine.

    Science.gov (United States)

    Li, Xiu Qin; Zhang, Qing He; Yang, Zong; Li, Hong Mei; Huang, Dong Feng

    2017-05-01

    In this paper, the effect of isotope-labeled analogs on the liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) measurement was evaluated based on the comparison research of electrospray ionization responses (ESI) and matrix effect of melamine, 13C3-melamine, 13C3+15N3-melamine, and 15N3-melamine. The isotope-labeled melamines had similar ionization efficiency with melamine in the electrospray ionization source, but the intensity of corresponding quantitative fragment ions had distinctive differences. Based on the density functional theory at the B3LYP/6-311+G** level, this phenomenon was explained very well. The rare cleavage pathways of melamine, which just could be exactly identified by 15N-labeled melamines, resulted in the difference of quantitative fragment ions between 15N-labeled melamines and melamine. The interaction of ESI response between melamine and isotope-labeled melamines was investigated using MRM monitor mode. 15N-labeled melamine had significant ion inter-suppression effect on melamine, while 13C-labeled melamine had little influence on melamine. Finally, the influence of different isotope-labeled melamines on the LC-IDMS result was evaluated using the IDMS correction factor (θ). Taking the determination of melamine in milk powder as an example, the matrix effects of different isotope-labeled melamines and melamine had notable difference and the impact of this difference on the measurement results depended on the concentrations of analyte and matrix solution. It was worth noting that 15N3-melamine exhibited significant ion suppression to melamine in matrix solution. The deviation of the results from IDMS method might reach 59% using 15N3-melamine as internal standard in special matrix solution. Graphical Abstract The comparison of ESI responses of melamine, 13C3-melamine, 13C3+15N3-melamine and 15N3-melamine.

  8. {sup 15}N-labeled nitrogen from green manure and ammonium sulfate utilization by the sugarcane ratoon

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosano, Edmilson Jose; Rossi, Fabricio, E-mail: ambrosano@apta.sp.gov.b [Agencia Paulista de Tecnologia dos Agronegocios (APTA), Piracicapa, SP (Brazil). Polo Rigional Centro Sul; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis; Cantarella, Heitor [Agencia Paulista de Tecnologia dos Agronegocios (APTA/IAC), Campinas, SP (Brazil). Instituto Agronomico de Campinas. Centro de Solos e Recursos Agroambientais; Ambrosano, Glaucia Maria Bovi [Universidade de Campinas (UNICAMP/FOP), Piracicaba, SP (Brazil). Fac. de Odontologia de Piracicaba. Dept. de Odontologia Social, Bioestatistica; Schammass, Eliana Aparecida [Agencia Paulista de Tecnologia dos Agronegocios (APTA/IZ), Nova Odessa, SP (Brazil). Instituto de Zootecnia; Muraoka, Takashi [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Fertilidade do solo

    2011-05-15

    Legumes as green manure are alternative sources of nitrogen (N) for crops and can supplement or even replace mineral nitrogen fertilization due to their potential for biological nitrogen fixation (BNF). The utilization of nitrogen by sugarcane (Saccharum spp.) fertilized with sunn hemp (Crotalaria juncea L.) and ammonium sulfate (AS) was evaluated using the {sup 15}N tracer technique. N was added at the rate of 196 and 70 kg ha{sup -1} as {sup 15}N-labeled sunn hemp green manure (SH) and as ammonium sulfate (AS), respectively. Treatments were: (I) Control; (II) AS{sup 15}N; (III) SH{sup 15}N + AS; (IV) SH{sup 15}N; and (V) AS{sup 15}N + SH. Sugarcane was cultivated for five years and was harvested three times. {sup 15}N recovery was evaluated in the two first harvests. In the sum of the three harvests, the highest stalk yields were obtained with a combination of green manure and inorganic N fertilizer; however, in the second cutting the yields were higher where SH was used than in plots with AS. The recovery of N by the first two consecutive harvests accounted for 19 to 21% of the N applied as leguminous green manure and 46 to 49% of the N applied as AS. The amounts of inorganic N, derived from both N sources, present in the 0-0.4 m layer of soil in the first season after N application and were below 1 kg ha{sup -1}. (author)

  9. Isotope Ratio Mass Spectrometry Monitoring of Nitrogen Volatilization from Beef Cattle Feces and 15N-Labeled Synthetic Urine

    Directory of Open Access Journals (Sweden)

    Ferouz Y. Ayadi

    2015-05-01

    Full Text Available A 15-day bench-scale manure storage experiment with a slurry mixture comprising beef cattle feces and synthetic urine with 15N-labeled urea was conducted to evaluate the source of volatilized ammonia nitrogen (NH3-N. Beef cattle feces was mixed daily in a 1:2.2 mass ratio with 15N-labeled urine and added for four consecutive days to 2-L storage containers and then left undisturbed for eleven days. Isotope ratio mass spectrometry was used to determine the origin of aerial NH3-N losses from the relative isotopic abundance of N in the 15N-labeled slurry mixture. On average 84% of total NH3-N losses originated from the urine portion and were highest during the first two to four days, when fresh material was added. After fresh material addition ceased, daily NH3-N emission from the urine decreased gradually, whereas emission from the feces remained relatively constant. Calculations showed that over 34% of aerial N was not captured, suggesting that other N gas emission is significant from slurry mixtures. Likely all uncaptured N losses were from urinary urea. The study verified the applicability of 15N-labeled synthetic urine for beef slurry mixtures. However, the results suggest further research to explain and model the NH3 and N release from fecal material is warranted and to determine the identity of the uncaptured N losses.

  10. Design and operation of a continuous 13C and 15N labeling chamber for uniform or differential, metabolic and structural, plant tissue isotope labeling

    Science.gov (United States)

    Tracing heavy stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes and soil organic matter formation to small-scale stable-isotope biomarker probing. Coupling multiple stable isotopes such as 13C with 15N, 18O o...

  11. Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh – a whole ecosystem 15N enrichment study

    Directory of Open Access Journals (Sweden)

    B. Gribsholt

    2007-01-01

    Full Text Available An intact tidal freshwater marsh system (3477 m2 was labelled by adding 15N-ammonium as a tracer to the flood water inundating the ecosystem. The appearance and retention of 15N-label in different marsh components (leaves, roots, sediment, leaf litter and invertebrate fauna was followed over 15 days. This allowed us to elucidate the direct assimilation and dependence on creek-water nitrogen on a relatively short term and provided an unbiased assessment of the relative importance of the various compartments within the ecosystem. Two separate experiments were conducted, one in spring/early summer (May 2002 when plants were young and building up biomass; the other in late summer (September 2003 when macrophytes were in a flowering or early senescent state. Nitrogen assimilation rate (per hour inundated was >3 times faster in May compared to September. On both occasions, however, the results clearly revealed that the less conspicuous compartments such as leaf litter and ruderal vegetations are more important in nitrogen uptake and retention than the prominent reed (Phragmites australis meadows. Moreover, short-term nitrogen retention in these nutrient rich marshes occurs mainly via microbial pathways associated with the litter and sediment. Rather than direct uptake by macrophytes, it is the large reactive surface area provided by the tidal freshwater marsh vegetation that is most crucial for nitrogen transformation, assimilation and short term retention in nutrient rich tidal freshwater marshes. Our results clearly revealed the dominant role of microbes in initial nitrogen retention in marsh ecosystems.

  12. Cyanobacteria-derived nitrogen uptake by benthic invertebrates in Lake Taihu: a mesocosm study using 15N labeling

    Directory of Open Access Journals (Sweden)

    Yu J.

    2014-01-01

    Full Text Available Eutrophication of lakes can lead to dominance by cyanobacteria, which are hardly used by zooplankton due to their low nutrition value. However, sedimented cyanobacterial detritus may be a useful source for benthic invertebrates. We studied the Microcystis-derived nitrogen incorporation in benthic invertebrates in Lake Taihu using stable isotopic nitrogen (15N as a tracer. The δ15N of all organisms increased significantly with time after addition of the labeled Microcystis detritus. δ15N values of POM and periphyton peaked earlier than for benthic invertebrates, and the maximum levels were also higher than bivalves, snails and worms (Limnodrilus spp.. Among benthic invertebrates, Radix swinhoei peaked later than other invertebrates, but the maximum level and the excess 15N of the last sampling day were higher. At the end of the experiment, approximately 70% of the added 15N was retained in the benthic food web, while only a small fraction (less than 1% of the added detritus 15N occurred in the pelagic food web. Our results suggest that nitrogen from cyanobacteria can be incorporated more in benthic than pelagic food webs and cyanobacterial blooms may contribute to the development of benthic animals.

  13. Factors controlling decomposition of soil organic matter in fallow systems of the high tropical Andes: A field simulation approach using 14C- and 15N-labelled plant material

    NARCIS (Netherlands)

    Bottner, P.; Pansu, M.; Sarmiento, L.; Hervé, D.; Callisaya-Bautista, R.; Metselaar, K.

    2006-01-01

    N-rich (C:N = 27) and N-poor (C:N = 130) wheat straw, labelled with 14 C and 15 N, was incubated for 2 yr in two major ecosystems of the upper elevation belt of cultivation in the high Andes: the moist Paramo (precipitation = 1329 mm, altitude = 3400 m asl, Andes of Merida, Venezuela) and the dry

  14. Synthesis and biosynthesis of {sup 13}C-, {sup 15}N-labeled deoxynucleosides useful for biomolecular structural determinations

    Energy Technology Data Exchange (ETDEWEB)

    Ashburn, D.A.; Garcia, K.; Hanners, J.L.; Silks, L.A. III; Unkefer, C.J. [Los Alamos National Laboratory, NM (United States)

    1994-12-01

    Currently, there is a great emphasis on elucidating the structure, function, and dynamics of DNA. Much of the research involved in this study uses nuclear magnetic resonance (NMR) spectroscopy. Effective use of NMR spectroscopy for DNA molecules with mw > 10,000 requires stable isotope enrichment. We present strategies for site-specific isotopic labeling of the purine bases adenosine and guanosine and the biosynthesis of (U-{sup 13}C, {sup 15}N) DNA from methylotropic bacteria. With commercially available 6-chloropurine, an effective two-step route leads to 2{prime}-deoxy-(amino-{sup 15}N)adenosine (dA). The resulting d(amino-{sup 15}N)A is used in a series of reactions to synthesize 2{prime}-deoxy-(2-{sup 13}C,1,amino-{sup 15}N{sub 2})guanosine or any combination thereof. An improved biosynthesis of labeled DNA has been accomplished using Methylobacterium extorquens AS1. Each liter of growth medium contains 4 g of methanol to yield 1 g of lyophilized cells. As much as 200 mg of RNA per liter of culture has been obtained. We are currently developing large-scale isolation protocols. General synthetic pathways to oligomeric DNA will be presented.

  15. Exploring the nitrogen ingestion of aphids--a new method using electrical penetration graph and (15N labelling.

    Directory of Open Access Journals (Sweden)

    Franziska Kuhlmann

    Full Text Available Studying plant-aphid interactions is challenging as aphid feeding is a complex process hidden in the plant tissue. Here we propose a combination of two well established methods to study nutrient acquisition by aphids focusing on the uptake of isotopically labelled nitrogen ((15N. We combined the Electrical Penetration Graph (EPG technique that allows detailed recording of aphid feeding behaviour and stable isotope ratio mass spectrometry (IRMS to precisely measure the uptake of nitrogen. Bird cherry-oat aphids Rhopalosiphum padi L. (Hemiptera, Aphididae fed for 24 h on barley plants (Hordeum vulgare L., cultivar Lina, Poaceae that were cultivated with a (15N enriched nutrient solution. The time aphids fed in the phloem was strongly positive correlated with their (15N uptake. All other single behavioural phases were not correlated with (15N enrichment in the aphids, which corroborates their classification as non-feeding EPG phases. In addition, phloem-feeding and (15N enrichment of aphids was divided into two groups. One group spent only short time in the phloem phase and was unsuccessful in nitrogen acquisition, while the other group displayed longer phloem-feeding phases and was successful in nitrogen acquisition. This suggests that several factors such as the right feeding site, time span of feeding and individual conditions play a role for the aphids to acquire nutrients successfully. The power of this combination of methods for studying plant-aphid interactions is discussed.

  16. A cost-effective approach to produce15N-labelled amino acids employing Chlamydomonas reinhardtii CC503.

    Science.gov (United States)

    Nicolás Carcelén, Jesús; Marchante-Gayón, Juan Manuel; González, Pablo Rodríguez; Valledor, Luis; Cañal, María Jesús; Alonso, José Ignacio García

    2017-08-18

    The use of enriched stable isotopes is of outstanding importance in chemical metrology as it allows the application of isotope dilution mass spectrometry (IDMS). Primary methods based on IDMS ensure the quality of the analytical measurements and traceability of the results to the international system of units. However, the synthesis of isotopically labelled molecules from enriched stable isotopes is an expensive and a difficult task. Either chemical and biochemical methods to produce labelled molecules have been proposed, but so far, few cost-effective methods have been described. The aim of this study was to use the microalgae Chlamydomonas reinhardtii to produce, at laboratory scale, 15 N-labelled amino acids with a high isotopic enrichment. To do that, a culture media containing 15 NH 4 Cl was used. No kinetic isotope effect (KIE) was observed. The labelled proteins biosynthesized by the microorganism were extracted from the biomass and the 15 N-labelled amino acids were obtained after a protein hydrolysis with HCl. The use of the wall deficient strain CC503 cw92 mt+ is fit for purpose, as it only assimilates ammonia as nitrogen source, avoiding isotope contamination with nitrogen from the atmosphere or the reagents used in the culture medium, and enhancing the protein extraction efficiency compared to cell-walled wild type Chlamydomonas. The isotopic enrichment of the labelled amino acids was calculated from their isotopic composition measured by gas chromatography mass spectrometry (GC-MS). The average isotopic enrichment for the 16 amino acids characterized was 99.56 ± 0.05% and the concentration of the amino acids in the hydrolysate ranged from 18 to 90 µg/mL. Previously reported biochemical methods to produce isotopically labelled proteins have been applied in the fields of proteomics and fluxomics. For these approaches, low amounts of products are required and the isotopic enrichment of the molecules has never been properly determined. So far, only 13

  17. The use of 15N-labeled dietary proteins for determining true ileal amino acid digestibilities is limited by their rapid recycling in the endogenous secretions of pigs

    NARCIS (Netherlands)

    Leterme, P.; Théwis, A.; François, E.; Leeuwen, P. van; Wathelet, B.; Huisman, J.

    1996-01-01

    We assessed the use of 15N-labeled dietary proteins as a possible tool for the determination of the true ileal amino acid (AA) digestibility in pigs. The first experiment was designed to study the dietary N excretion pattern at the ileum subsequent to the ingestion of a single 15N-labeled meal. In a

  18. Production of 15N-Labelled Liquid Organic Fertilisers Based on Manure and Crop Residue for Use in Fertigation Studies.

    Directory of Open Access Journals (Sweden)

    Belén Martínez-Alcántara

    Full Text Available Large quantities of crop residue and animal manure from agricultural and livestock activities are annually produced worldwide. With proper management, these residues are potentially valuable sources of plant nutrients, mainly N. Recycling such subproducts in sustainably-based agricultural systems can minimise the use of mineral fertilisers, and hence reduce the potential risk of surface and groundwater pollution. Therefore, the purpose of this study was to obtain (small scale two liquid labelled-organic fertilisers, an animal- and a vegetal-based organic (AO and VO, respectively fertiliser, to be used as organic N sources in subsequent fertigation studies. Forage maize (Zea mays L. grown under 15N-labelled fertiliser supply was used as raw material for VO fertiliser production, and also as 15N-labelled sheep feed to obtain 15N-labelled manure. The labelled faeces fraction was used as raw material for the AO fertiliser. The VO fertiliser was obtained after an acidic and an enzyme-driven hydrolysis. The AO fertiliser was obtained after acidic hydrolysis. The VO liquid fertiliser presented an N concentration of 330 mg·L-1, 85% of total N was organic, while ammonium and nitrate N accounted for 55% and 45% of the mineral nitrogen fraction, respectively. This fertiliser also exhibited high K, Ca and S concentrations and notable values for the remaining macro- and micronutrients. The AO liquid fertiliser had a similar total N concentration (496 mg·L-1, 82% of total N in an organic form to that of VO, but its mineral N fraction significantly differed, which came in a predominantly (95% ammonia form. It also had a high content of N, P, K and other macronutrients, and sufficient Fe, Zn, Mn, Cu and B levels, which suggests its suitability as a potential fertiliser. The percentage of 15N enrichment in both VO and AO liquid fertilisers exceeded 2% 15N atom excess, which enabled their use in subsequent assays run to assess nitrogen uptake efficiency.

  19. Assessment of a delta15N isotopic method to indicate anthropogenic eutrophication in aquatic ecosystems.

    Science.gov (United States)

    Cole, Marci L; Valiela, Ivan; Kroeger, Kevin D; Tomasky, Gabrielle L; Cebrian, Just; Wigand, Cathleen; McKinney, Richard A; Grady, Sara P; Carvalho da Silva, Maria Helena

    2004-01-01

    Increased anthropogenic delivery of nutrients to water bodies, both freshwater and estuarine, has caused detrimental changes in habitat, food web structure, and nutrient cycling. Nitrogen-stable isotopes may be suitable indicators of such increased nutrient delivery. In this study, we looked at the differences in response of macrophyte delta15N values to anthropogenic N across different taxonomic groups and geographic regions to test a stable isotopic method for detecting anthropogenic impacts. Macrophyte delta15N values increased with wastewater input and water-column dissolved inorganic nitrogen (DIN) concentration. When macrophytes were divided into macroalgae and plants, they responded similarly to increases in wastewater N, although macroalgae was a more reliable indicator of both wastewater inputs and water-column DIN concentrations. Smooth cordgrass (Spartina alterniflora Loisel.) Delta15N increased uniformly with wastewater inputs across a geographic range. We used the relationship derived between S. alterniflora and relative wastewater load to predict wastewater loads in locations lacking quantitative land use data. The predictions matched well with known qualitative information, proving the use of a stable isotopic method for predicting wastewater input.

  20. O potencial da rotulação metabólica de 15N para a pesquisa de esquizofrenia The potential of 15N metabolic labeling for schizophrenia research

    Directory of Open Access Journals (Sweden)

    Michaela D Filiou

    2012-01-01

    Full Text Available Pesquisas em psiquiatria ainda necessitam de estudos não dirigidos por hipóteses para revelar fundamentos neurobiológicos e biomarcadores moleculares para distúrbios psiquiátricos. Metodologias proteômicas disponibilizam uma série de ferramentas para esses fins. Apresentamos o princípio de rotulação metabólica utilizando 15N para proteômica quantitativa e suas aplicações em modelos animais de fenótipos psiquiátricos com um foco particular em esquizofrenia. Exploramos o potencial de rotulação metabólica por 15N em diferentes tipos de experimentos, bem como suas considerações metodológicas.Psychiatric research is in need of non-hypothesis driven approaches to unravel the neurobiological underpinnings and identify molecular biomarkers for psychiatric disorders. Proteomics methodologies constitute a state-of-the-art toolbox for biomarker discovery in psychiatric research. Here we present the principle of in vivo 15N metabolic labeling for quantitative proteomics experiments and applications of this method in animal models of psychiatric phenotypes, with a particular focus on schizophrenia. Additionally we explore the potential of 15N metabolic labeling in different experimental set-ups as well as methodological considerations of 15N metabolic labeling-based quantification studies.

  1. O potencial da rotulação metabólica de 15N para a pesquisa de esquizofrenia The potential of 15N metabolic labeling for schizophrenia research

    Directory of Open Access Journals (Sweden)

    Michaela D. Filiou

    2013-01-01

    Full Text Available Pesquisas em psiquiatria ainda necessitam de estudos não dirigidos por hipóteses para revelar fundamentos neurobiológicos e biomarcadores moleculares para distúrbios psiquiátricos. Metodologias proteômicas disponibilizam uma série de ferramentas para esses fins. Apresentamos o princípio de rotulação metabólica utilizando 15N para proteômica quantitativa e suas aplicações em modelos animais de fenótipos psiquiátricos com um foco particular em esquizofrenia. Exploramos o potencial de rotulação metabólica por 15N em diferentes tipos de experimentos, bem como suas considerações metodológicas.Psychiatric research is in need of non-hypothesis driven approaches to unravel the neurobiological underpinnings and identify molecular biomarkers for psychiatric disorders. Proteomics methodologies constitute a state-of-the-art toolbox for biomarker discovery in psychiatric research. Here we present the principle of in vivo 15N metabolic labeling for quantitative proteomics experiments and applications of this method in animal models of psychiatric phenotypes, with a particular focus on schizophrenia. Additionally we explore the potential of 15N metabolic labeling in different experimental set-ups as well as methodological considerations of 15N metabolic labeling-based quantification studies.

  2. Net postprandial utilization of [15N]-labeled milk protein nitrogen is influenced by diet composition in humans.

    Science.gov (United States)

    Gaudichon, C; Mahé, S; Benamouzig, R; Luengo, C; Fouillet, H; Daré, S; Van Oycke, M; Ferrière, F; Rautureau, J; Tomé, D

    1999-04-01

    The aim of this study was to follow the fate of dietary nitrogen to assess the postprandial utilization of purified milk protein and to determine the acute influence of energy nutrients. For this purpose, a [15N]-labeling dietary protein approach was used. Twenty-five subjects swallowed an ileal tube and ingested [15 N]-milk protein alone or supplemented with either milk fat or sucrose. The absorption and postprandial deamination of dietary protein was monitored for 8 h. Sucrose delayed the absorption of protein longer than fat, but the ileal digestibility did not differ among groups (94.5-94.8%). Sucrose, but not fat, significantly reduced the postprandial transfer of [15N]-milk nitrogen to urea. Consequently, the net postprandial protein utilization (NPPU) of milk protein calculated 8 h after meal ingestion was 80% when ingested either alone or supplemented with fat and was significantly greater with sucrose (NPPU = 85%). This study shows that energy nutrients do not affect the nitrogen absorption but modify the metabolic utilization of dietary protein in the phase of nitrogen gain. Our method provides information concerning the deamination kinetics of dietary amino acids and further allows the detection of differences of dietary protein utilization in acute conditions. The diet composition should be carefully considered, and protein quality must be determined under optimal conditions of utilization.

  3. Nitrogen incorporation and retention by bacteria, algae, and fauna in a subtropical, intertidal sediment: An in situ 15N-labeling study

    NARCIS (Netherlands)

    Veuger, B.; Eyre, B.D.; Maher, D.; Middelburg, J.J.

    2007-01-01

    We performed a 15N-labeling study to investigate nitrogen incorporation and retention by the benthic microbial community (bacteria and benthic microalgae) and fauna in the intertidal sediment of the subtropical Australian Brunswick Estuary. The main experiment involved an in situ 15N pulse–chase

  4. Medium-term response of microbial community to rhizodeposits of white clover and ryegrass and tracing of active processes induced by 13C and 15N labelled exudates

    DEFF Research Database (Denmark)

    Kusliene, Gedrime; Rasmussen, Jim; Kuzyakov, Yakov

    2014-01-01

    microbial groups in soil under white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.) following leaf-labelling with 13C-bicarbonate and 15N-urea. In this way microbial N and 15N and the composition of PLFAs reflect the medium-term (two months) response of microorganisms to rhizodeposits...

  5. Nitrogen immobilization and mineralization during initial decomposition of 15N-labelled pea and barley residues

    DEFF Research Database (Denmark)

    Jensen, E.S.

    1997-01-01

    The immobilization and mineralization of N following plant residue incorporation were studied in a sandy loam soil using N-15-labelled field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) straw. Both crop residues caused a net immobilization of soil-derived inorganic N during...... the complete incubation period of 84 days. The maximum rate of N immobilization was found to 12 and 18 mg soil-derived N g(-1) added C after incorporation of pea and barley residues, respectively. After 7 days of incubation, 21% of the pea and 17% of the barley residue N were assimilated by the soil microbial...... the decomposition of the barley residue. The net mineralization of residue-derived N was 2% in the barley and 22% in the pea residue treatment after 84 days of incubation. The results demonstrated that even if crop residues have a relative low C/N ratio (15), transient immobilization of soil N in the microbial...

  6. Partitioning Residue-derived and Residue-induced Emissions of N2O Using 15N-labelled Crop Residues

    Science.gov (United States)

    Farrell, R. E.; Carverhill, J.; Lemke, R.; Knight, J. D.

    2014-12-01

    Estimates of N2O emissions in Canada indicate that 17% of all agriculture-based emissions are associated with the decomposition of crop residues. However, research specific to the western Canadian prairies (including Saskatchewan) has shown that the N2O emission factor for N sources in this region typically ranges between 0.2 and 0.6%, which is well below the current IPCC default emission factor of 1.0%. Thus, it stands to reason that emissions from crop residues should also be lower than those calculated using the current IPCC emission factor. Current data indicates that residue decomposition, N mineralization and N2O production are affected by a number of factors such as C:N ratio and chemical composition of the residue, soil type, and soil water content; thus, a bench-scale incubation study was conducted to examine the effects of soil type and water content on N2O emissions associated with the decomposition of different crop residues. The study was carried out using soils from the Black, Dark Brown, Brown, and Gray soil zones and was conducted at both 50% and 70% water-filled pore space (WFPS); the soils were amended with 15N-labeled residues of wheat, pea, canola, and flax, or with an equivalent amount of 15N-labeled urea; 15N2O production was monitored using a Picarro G5101-i isotopic N2O analyzer. Crop residue additions to the soils resulted in both direct and indirect emissions of N2O, with residue derived emissions (RDE; measured as 15N2O) generally exceeding residue-induced emissions (RIE) at 50% WFPS—with RDEs ranging from 42% to 88% (mean = 58%) of the total N2O. Conversely, at 70% WFPS, RDEs were generally lower than RIEs—ranging from 21% to 83% (mean = 48%). Whereas both water content and soil type had an impact on N2O production, there was a clear and consistent trend in the emission factors for the residues; i.e., emissions were always greatest for the canola residue and lowest for the wheat residue and urea fertilizer; and intermediate for pea

  7. Estimation of internal and external nitrogen for corals with a long-term 15N-labelling experiment and subsequent model calculations

    Science.gov (United States)

    Tanaka, Yasuaki; Grottoli, Andréa; Matsui, Yohei; Suzuki, Atsushi; Sakai, Kazuhiko

    2014-05-01

    Coral reef ecosystems maintain high primary productivity though the seawater is extremely oligotrophic. One of the hypotheses to explain this paradox is the recycling of nutrients in animal-algal symbiotic organisms such as corals. It is relatively easy to measure nutrient uptake rates by corals from seawater, but the proportion of internally circulating nutrients between the coral host and the endosymbiotic algae (zooxanthellae) is more challenging. Here, we performed a long-term and continuous 15N-labelling experiment to quantify the proportionate contribution of seawater (external N source) and the animal host (internal N source) to the total N influx in the endosymbiotic algae. Branches from the scleractinian corals Porites cylindrica and Montipora digitata from Okinawa, Japan, were cultured for 2 months in indoor, flow-through, filtered seawater tanks with the continuous supply of 15N-labelled nitrate. At the initial and after 2, 4, and 9 weeks of the study, coral branches were collected and the algal and animal fractions were separated for isotopic analyses. In both corals, the N isotope ratio of symbiotic algae exponentially increased and the values were much higher than those of the host tissue, suggesting that the algae had a faster turnover N time than the animal host. Algal and host N biomass normalized to the coral surface area slowly decreased in both coral species over the study period. To calculate the contribution of internal and external N, a simple mixing model of algal N metabolism was designed. Using differential equations of 15N balance and N biomass balance, F1 and F2 (external and internal N fluxes to symbiotic algae, respectively) were expressed as the functions of time. The model calculations showed that F2 was much higher than F1 in P. cylindrica and the percentage of internal N to the total influx N (PIN) was >70%. On the other hand, the contribution of F1 and F2 was comparable in M. digitata and the PIN was 40-70%. These results

  8. Nitrous oxide emissions from soil amended with 15N-labelled urea with nitrification inhibitor (Nitrapyrin) and mulch

    Science.gov (United States)

    Khan, Aamir; Heiling, Maria; Zaman, Mohammad; Resch, Christian

    2017-04-01

    Nitrous oxide (N2O), one of the key greenhouse and ozone (O3) depleting gases, constitutes 7% of the anthropogenic greenhouse effect. Its global warming potential is 310 times higher than that of carbon dioxide (CO2) and 16 times than methane (CH4) over a 100-year period. To develop mitigation tools for N2O emissions, and to investigate the relationship between gross N transformation and N2O emission from soil, it is imperative to understand N2O emission from soils as influenced by N inputs, environmental conditions and farm management practices. The use of nitrification inhibitor such as Nitrapyrin and crop residues (mulch) may have a role in mitigating N2O losses from soil because of their effects on nitrification and denitrification. It prevents hydrolytic action on urea and keeps nitrogen in ammonium form. To determine the effects of urea applied with nitrification inhibitor and mulch on N2O emissions from soil, an incubation experiment was conducted under controlled moisture of 60% water filled pore space (WFPS) and temperature (20±2oC) conditions. Soil samples (0-20 cm soil depth) collected from an arable site were treated with 15N-labelled urea (5 atom %) at 150 kg N/ha rate. The 5 treatments including control, (urea, urea with Nitrapyrin (800 g/100 kg urea), urea with mulch (5 tons/ha) and urea with Nitrapyrin and mulch) were replicated 4 times using 500 ml glass jars. The N2O isotopic signature and the intramolecular distribution of 15N were measured by off-axis integrated cavity output spectroscopy (Los Gatos Research). The preliminary results showed that nitrification inhibitor (Nitrapyrin) can be used to distinguish between different pathways of N2O production from soil. In addition to the site preference of the 15N promises to be a helpful tool to determine the source of the generated N2O.

  9. Salt marsh ecosystem biogeochemical responses to nutrient enrichment: a paired 15N tracer study.

    Science.gov (United States)

    Drake, D C; Peterson, Bruce J; Galván, Kari A; Deegan, Linda A; Hopkinson, Charles; Johnson, J Michael; Koop-Jakobsen, K; Lemay, Lynsey E; Picard, Christian

    2009-09-01

    We compared processing and fate of dissolved NO3- in two New England salt marsh ecosystems, one receiving natural flood tide concentrations of approximately 1-4 micromol NO3-/ L and the other receiving experimentally fertilized flood tides containing approximately 70-100 micromol NO3-/ L. We conducted simultaneous 15NO3- (isotope) tracer additions from 23 to 28 July 2005 in the reference (8.4 ha) and fertilized (12.4 ha) systems to compare N dynamics and fate. Two full tidal cycles were intensively studied during the paired tracer additions. Resulting mass balances showed that essentially 100% (0.48-0.61 mol NO3-N.ha(-1).h(-1)) of incoming NO3- was assimilated, dissimilated, sorbed, or sedimented (processed) within a few hours in the reference system when NO3- concentrations were 1.3-1.8 micromol/L. In contrast, only 50-60% of incoming NO3- was processed in the fertilized system when NO3- concentrations were 84-96 micromol/L; the remainder was exported in ebb tidewater. Gross NO3- processing was approximately 40 times higher in the fertilized system at 19.34-24.67 mol NO3-N.ha(-1).h(-1). Dissimilatory nitrate reduction to ammonium was evident in both systems during the first 48 h of the tracer additions but <1% of incoming 15NO3- was exported as 15NH4+. Nitrification rates calculated by 15NO3- dilution were 6.05 and 4.46 mol.ha(-1).h(-1) in the fertilized system but could not be accurately calculated in the reference system due to rapid (<4 h) NO3- turnover. Over the five-day paired tracer addition, sediments sequestered a small fraction of incoming NO3-, although the efficiency of sequestration was 3.8% in the reference system and 0.7% in the fertilized system. Gross sediment N sequestration rates were similar at 13.5 and 12.6 mol.ha(-1).d(-1), respectively. Macrophyte NO3- uptake efficiency, based on tracer incorporation in aboveground tissues, was considerably higher in the reference system (16.8%) than the fertilized system (2.6%), although bulk uptake of NO3

  10. Turnover of manure 15N-labelled ammonium during composting and soil application as affected by lime and superphosphate addition

    DEFF Research Database (Denmark)

    Tran, Tien Minh; Luxhøi, Jesper; Jensen, Lars Stoumann

    2012-01-01

    ). The NH4-N pool in the pig manure was initially labeled with 15N to determine the fate of manure NH4-N during composting. The composts were subsequently applied to soil to investigate the effects on soil mineral N and to trace the 15N during 60 d of incubation at 25°C. Of the initial manure 15NH4-N...... or effectively in balance. In soil with Lime compost, net N immobilization was strong in the fi rst 10 d, but then net N mineralization dominated the remaining period of soil incubation. Overall, adding lime before composting reduced the NH4-N content in the compost and the amount available in soil, while adding......To determine N turnover and losses during aerobic composting of animal manure, a 41-d laboratory study was performed on pig manure composting with three additive treatments (Straw: pig manure + straw only; Lime: pig manure + straw + quick lime; and SSP: pig manure + straw + single superphosphate...

  11. Nitrogen removal in Myriophyllum aquaticum wetland microcosms for swine wastewater treatment: 15 N-labelled nitrogen mass balance analysis.

    Science.gov (United States)

    Zhang, Shunan; Liu, Feng; Xiao, Runlin; He, Yang; Wu, Jinshui

    2017-01-01

    Ecological treatments are effective for treating agricultural wastewater. In this study, wetland microcosms vegetated with Myriophyllum aquaticum were designed for nitrogen (N) removal from two strengths of swine wastewater, and 15 N-labelled ammonium (NH4+ -N) was added to evaluate the dominant NH4+ -N removal pathway. The results showed that 98.8% of NH4+ -N and 88.3% of TN (TN: 248.6 mg L-1 ) were removed from low-strength swine wastewater (SW1) after an incubation of 21 days, with corresponding values for high-strength swine wastewater (SW2) being 99.2% of NH4+ -N and 87.8% of TN (TN: 494.9 mg L-1 ). Plant uptake and soil adsorption respectively accounted for 24.0% and 15.6% of the added 15 N. Meanwhile, above-ground tissues of M. aquaticum had significantly higher biomass and TN content than below-ground (P wetlands for high N-loaded animal wastewater treatment. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  12. Efficiency of soil and fertilizer nitrogen in relation to rice variety and application time using sup(15)N labelled fertilizer: Pt. 3. Top-dressing with sup(15)N fertilizer in fields

    Energy Technology Data Exchange (ETDEWEB)

    Park, H. (Korea Ginseng and Tobacco Research Inst., Seoul (Republic of Korea)); Seok, S.J. (Office of Rural Development, Suwon (Republic of Korea))

    1982-09-01

    Use efficiency of top-dressed labelled nitrogen (30% at ear formation stage) ranged 23 to 61%(five fields) with no clear difference between varieties. In high yield soil the use efficiency of top-dressed nitrogen was higher and more than 50% of fertilizer nitrogen in plant seemed to be taken up after ear formation, sup(15)N excess was greastest in grain indicating that top-dressed nitrogen translocates easily to grain. The differences of sup(15)N excess between grain and straw was greater in Tongil line than in the local indicating faster nitrogen translocation in Tongil. Percent nitrogen derived from top-dressed nitrogen ranged 14 to 27% in aerial part. Two 3-hill plots per treatment could be enough for sup(15)N experiment under field condition if there is specific care.

  13. Nitrate removal in stream ecosystems measured by 15N addition experiments: Total uptake

    Science.gov (United States)

    Hall, R.O.; Tank, J.L.; Sobota, D.J.; Mulholland, P.J.; O'Brien, J. M.; Dodds, W.K.; Webster, J.R.; Valett, H.M.; Poole, G.C.; Peterson, B.J.; Meyer, J.L.; McDowell, W.H.; Johnson, S.L.; Hamilton, S.K.; Grimm, N. B.; Gregory, S.V.; Dahm, Clifford N.; Cooper, L.W.; Ashkenas, L.R.; Thomas, S.M.; Sheibley, R.W.; Potter, J.D.; Niederlehner, B.R.; Johnson, L.T.; Helton, A.M.; Crenshaw, C.M.; Burgin, A.J.; Bernot, M.J.; Beaulieu, J.J.; Arangob, C.P.

    2009-01-01

    We measured uptake length of 15NO-3 in 72 streams in eight regions across the United States and Puerto Rico to develop quantitative predictive models on controls of NO-3 uptake length. As part of the Lotic Intersite Nitrogen eXperiment II project, we chose nine streams in each region corresponding to natural (reference), suburban-urban, and agricultural land uses. Study streams spanned a range of human land use to maximize variation in NO-3 concentration, geomorphology, and metabolism. We tested a causal model predicting controls on NO-3 uptake length using structural equation modeling. The model included concomitant measurements of ecosystem metabolism, hydraulic parameters, and nitrogen concentration. We compared this structural equation model to multiple regression models which included additional biotic, catchment, and riparian variables. The structural equation model explained 79% of the variation in log uptake length (S Wtot). Uptake length increased with specific discharge (Q/w) and increasing NO-3 concentrations, showing a loss in removal efficiency in streams with high NO-3 concentration. Uptake lengths shortened with increasing gross primary production, suggesting autotrophic assimilation dominated NO-3 removal. The fraction of catchment area as agriculture and suburban-urban land use weakly predicted NO-3 uptake in bivariate regression, and did improve prediction in a set of multiple regression models. Adding land use to the structural equation model showed that land use indirectly affected NO-3 uptake lengths via directly increasing both gross primary production and NO-3 concentration. Gross primary production shortened SWtot, while increasing NO-3 lengthened SWtot resulting in no net effect of land use on NO- 3 removal. ?? 2009.

  14. Bicarbonate as tracer for plant assimilated C and homogeneity of 14C and 15N distribution in ryegrass and white clover tissue by alternative labeling approaches

    DEFF Research Database (Denmark)

    Rasmussen, Jim; Kusliene, Gedrime; Jacobsen, Ole Stig

    2013-01-01

    if bicarbonate can be used to introduce 14C (or 13C) into white clover and ryegrass, and (ii) compared the patterns of 14C and 15N allocation in white clover and ryegrass to evaluate the homogeneity of tracer distribution after two alternative labeling approaches. Methods Perennial ryegrass and white clover were...... parts with high and low 14C activity were separated and analyzed for 15N enrichment. Results Bicarbonate applied by leaf-labeling efficiently introduced 14C into both white clover and ryegrass, although the 14C activity in particular for white clover was found predominantly in the labeled leaf. Using 14...

  15. An economic approach to efficient isotope labeling in insect cells using homemade {sup 15}N-, {sup 13}C- and {sup 2}H-labeled yeast extracts

    Energy Technology Data Exchange (ETDEWEB)

    Opitz, Christian; Isogai, Shin; Grzesiek, Stephan, E-mail: Stephan.Grzesiek@unibas.ch [University of Basel, Focal Area Structural Biology and Biophysics, Biozentrum (Switzerland)

    2015-07-15

    Heterologous expression of proteins in insect cells is frequently used for crystallographic structural studies due to the high yields even for challenging proteins requiring the eukaryotic protein processing capabilities of the host. However for NMR studies, the need for isotope labeling poses extreme challenges in eukaryotic hosts. Here, we describe a robust method to achieve uniform protein {sup 15}N and {sup 13}C labeling of up to 90 % in baculovirus-infected insect cells. The approach is based on the production of labeled yeast extract, which is subsequently supplemented to insect cell growth media. The method also allows deuteration at levels of >60 % without decrease in expression yield. The economic implementation of the labeling procedures into a standard structural biology laboratory environment is described in a step-by-step protocol. Applications are demonstrated for a variety of NMR experiments using the Abelson kinase domain, GFP, and the beta-1 adrenergic receptor as examples. Deuterated expression of the latter provides spectra of very high quality of a eukaryotic G-protein coupled receptor.

  16. Nitrogen-15 labeling of Crotalaria juncea green manure Marcação do adubo verde Crotalaria juncea com 15N

    Directory of Open Access Journals (Sweden)

    Edmilson José Ambrosano

    2003-02-01

    Full Text Available Most studies dealing with the utilization of 15N labeled plant material do not present details about the labeling technique. This is especially relevant for legume species since biological nitrogen fixation difficults plant enrichment. A technique was developed for labeling leguminous plant tissue with 15N to obtain labeled material for nitrogen dynamics studies. Sun hemp (Crotalaria juncea L. was grown on a Paleudalf, under field conditions. An amount of 58.32 g of urea with 70.57 ± 0.04 atom % 15N was sprayed three times on plants grown on eight 6-m²-plots. The labelled material presented 2.412 atom % 15N in a total dry matter equivalent to 9 Mg ha-1 This degree of enrichment enables the use of the green manure in pot or field experiments requiring 15N-labeled material.A grande maioria dos estudos com a utilização de material vegetal marcado com o isótopo 15N não apresentam detalhes tão importantes sobre como foram obtidos esses materiais. Em se tratando de marcação de leguminosas as dificuldades em se obter material marcado com 15N são ainda maiores pelo fato de serem plantas fixadoras de nitrogênio. Isso posto foi estabelecida uma técnica de marcação de leguminosas com nitrogênio (15N, com o objetivo de obter material vegetal marcado isotopicamente para estudos de dinâmica do nitrogênio. Cultivou-se a leguminosa crotalária júncea (Crotalaria juncea L., em Argissolo Vermelho Amarelo distrófico, em campo. Ao se aplicarem via foliar 58,32 gramas de uréia em oito canteiros experimentais, (uréia com 70,57 ± 0,04% de átomos de 15N parceladas em três vezes, obteve-se material vegetal marcado seco que continha 2,412 % em átomos de 15N em uma massa seca equivalente a 9 Mg ha-1. Essa marcação permite o uso dessa massa vegetal em estudos de dinâmica de nitrogênio.

  17. Interresidue carbonyl-carbonyl polarization transfer experiments in uniformly 13C, 15N-labeled peptides and proteins

    Science.gov (United States)

    Janik, Rafal; Ritz, Emily; Gravelle, Andrew; Shi, Lichi; Peng, Xiaohu; Ladizhansky, Vladimir

    2010-03-01

    In this work, we demonstrate that Homonuclear Rotary Resonance Recoupling (HORROR) can be used to reintroduce carbonyl-carbonyl interresidue dipolar interactions and to achieve efficient polarization transfer between carbonyl atoms in uniformly 13C, 15N-labeled peptides and proteins. We show that the HORROR condition is anisotropically broadened and overall shifted to higher radio frequency intensities because of the CSA effects. These effects are analyzed theoretically using Average Hamiltonian Theory. At spinning frequencies used in this study, 22 kHz, this broadening is experimentally found to be on the order of a kilohertz at a proton field of 600 MHz. To match HORROR condition over all powder orientations, variable amplitude radio frequency (RF) fields are required, and efficient direct transfers on the order of 20-30% can be straightforwardly established. Two- and three-dimensional chemical shift correlation experiments establishing long-range interresidue connectivities (e.g., (N[i]-CO[i - 2])) are demonstrated on the model peptide N-acetyl-valine-leucine, and on the third immunoglobulin binding domain of protein G. Possible future developments are discussed.

  18. Insights into nitrogen allocation and recycling from nitrogen elemental analysis and 15N isotope labelling in 14 genotypes of willow.

    Science.gov (United States)

    Brereton, Nicholas J B; Pitre, Frederic E; Shield, Ian; Hanley, Steven J; Ray, Michael J; Murphy, Richard J; Karp, Angela

    2014-11-01

    Minimizing nitrogen (N) fertilization inputs during cultivation is essential for sustainable production of bioenergy and biofuels. The biomass crop willow (Salix spp.) is considered to have low N fertilizer requirements due to efficient recycling of nutrients during the perennial cycle. To investigate how successfully different willow genotypes assimilate and allocate N during growth, and remobilize and consequently recycle N before the onset of winter dormancy, N allocation and N remobilization (to and between different organs) were examined in 14 genotypes of a genetic family using elemental analysis and (15)N as a label. Cuttings were established in pots in April and sampled in June, August and at onset of senescence in October. Biomass yield of the trees correlated well with yields recorded in the field. Genotype-specific variation was observed for all traits measured and general trends spanning these sampling points were identified when trees were grouped by biomass yield. Nitrogen reserves in the cutting fuelled the entirety of the canopy establishment, yet earlier cessation of this dependency was linked to higher biomass yields. The stem was found to be the major N reserve by autumn, which constitutes a major source of N loss at harvest, typically every 2-3 years. These data contribute to understanding N remobilization in short rotation coppice willow and to the identification of traits that could potentially be selected for in breeding programmes to further improve the sustainability of biomass production. © The Author 2013. Published by Oxford University Press.

  19. Quantifying biological nitrogen fixation of different catch crops, and residual effects of roots and tops on nitrogen uptake in barley using in-situ 15N labelling

    DEFF Research Database (Denmark)

    Li, Xiaoxi; Sørensen, Peter; Li, F C

    2015-01-01

    in microplots by 15N labelling. Their residual effects on spring barley were tested against two non-LBCCs (perennial ryegrass, fodder radish) after spring incorporation of CC tops or roots in monoliths. Total N accumulated in LBCCs was 153–226 kg N ha−1, of which 62–66 % was derived from BNF in tops and 31...

  20. Fermentation and Cost-Effective 13C/15N Labeling of the Nonribosomal Peptide Gramicidin S for Nuclear Magnetic Resonance Structure Analysis.

    Science.gov (United States)

    Berditsch, Marina; Afonin, Sergii; Steineker, Anna; Orel, Nataliia; Jakovkin, Igor; Weber, Christian; Ulrich, Anne S

    2015-06-01

    Gramicidin S (GS) is a nonribosomally synthesized decapeptide from Aneurinibacillus migulanus. Its pronounced antibiotic activity is attributed to amphiphilic structure and enables GS interaction with bacterial membranes. Despite its medical use for over 70 years, the peptide-lipid interactions of GS and its molecular mechanism of action are still not fully understood. Therefore, a comprehensive structural analysis of isotope-labeled GS needs to be performed in its biologically relevant membrane-bound state, using advanced solid-state nuclear magnetic resonance (NMR) spectroscopy. Here, we describe an efficient method for producing the uniformly (13)C/(15)N-labeled peptide in a minimal medium supplemented by selected amino acids. As GS is an intracellular product of A. migulanus, we characterized the producer strain DSM 5759 (rough-convex phenotype) and examined its biosynthetic activity in terms of absolute and biomass-dependent peptide accumulation. We found that the addition of either arginine or ornithine increases the yield only at very high supplementing concentrations (1% and 0.4%, respectively) of these expensive (13)C/(15)N-labeled amino acids. The most cost-effective production of (13)C/(15)N-GS, giving up to 90 mg per gram of dry cell weight, was achieved in a minimal medium containing 1% (13)C-glycerol and 0.5% (15)N-ammonium sulfate, supplemented with only 0.025% of (13)C/(15)N-phenylalanine. The 100% efficiency of labeling is corroborated by mass spectrometry and preliminary solid-state NMR structure analysis of the labeled peptide in the membrane-bound state. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  1. Comparing the influence of wildfire and prescribed burns on watershed nitrogen biogeochemistry using 15N natural abundance in terrestrial and aquatic ecosystem components.

    Science.gov (United States)

    Stephan, Kirsten; Kavanagh, Kathleen L; Koyama, Akihiro

    2015-01-01

    We evaluated differences in the effects of three low-severity spring prescribed burns and four wildfires on nitrogen (N) biogeochemistry in Rocky Mountain headwater watersheds. We compared paired (burned/unburned) watersheds of four wildfires and three spring prescribed burns for three growing seasons post-fire. To better understand fire effects on the entire watershed ecosystem, we measured N concentrations and δ15N in both the terrestrial and aquatic ecosystems components, i.e., soil, understory plants in upland and riparian areas, streamwater, and in-stream moss. In addition, we measured nitrate reductase activity in foliage of Spiraea betulifolia, a dominant understory species. We found increases of δ15N and N concentrations in both terrestrial and aquatic ecosystem N pools after wildfire, but responses were limited to terrestrial N pools after prescribed burns indicating that N transfer from terrestrial to aquatic ecosystem components did not occur in low-severity prescribed burns. Foliar δ15N differed between wildfire and prescribed burn sites; the δ15N of foliage of upland plants was enriched by 2.9 ‰ (difference between burned and unburned watersheds) in the first two years after wildfire, but only 1.3 ‰ after prescribed burns. In-stream moss δ15N in wildfire-burned watersheds was enriched by 1.3 ‰, but there was no response by moss in prescription-burned watersheds, mirroring patterns of streamwater nitrate concentrations. S. betulifolia showed significantly higher nitrate reductase activity two years after wildfires relative to corresponding unburned watersheds, but no such difference was found after prescribed burns. These responses are consistent with less altered N biogeochemistry after prescribed burns relative to wildfire. We concluded that δ15N values in terrestrial and aquatic plants and streamwater nitrate concentrations after fire can be useful indicators of the magnitude and duration of fire effects and the fate of post

  2. Comparing the influence of wildfire and prescribed burns on watershed nitrogen biogeochemistry using 15N natural abundance in terrestrial and aquatic ecosystem components.

    Directory of Open Access Journals (Sweden)

    Kirsten Stephan

    Full Text Available We evaluated differences in the effects of three low-severity spring prescribed burns and four wildfires on nitrogen (N biogeochemistry in Rocky Mountain headwater watersheds. We compared paired (burned/unburned watersheds of four wildfires and three spring prescribed burns for three growing seasons post-fire. To better understand fire effects on the entire watershed ecosystem, we measured N concentrations and δ15N in both the terrestrial and aquatic ecosystems components, i.e., soil, understory plants in upland and riparian areas, streamwater, and in-stream moss. In addition, we measured nitrate reductase activity in foliage of Spiraea betulifolia, a dominant understory species. We found increases of δ15N and N concentrations in both terrestrial and aquatic ecosystem N pools after wildfire, but responses were limited to terrestrial N pools after prescribed burns indicating that N transfer from terrestrial to aquatic ecosystem components did not occur in low-severity prescribed burns. Foliar δ15N differed between wildfire and prescribed burn sites; the δ15N of foliage of upland plants was enriched by 2.9 ‰ (difference between burned and unburned watersheds in the first two years after wildfire, but only 1.3 ‰ after prescribed burns. In-stream moss δ15N in wildfire-burned watersheds was enriched by 1.3 ‰, but there was no response by moss in prescription-burned watersheds, mirroring patterns of streamwater nitrate concentrations. S. betulifolia showed significantly higher nitrate reductase activity two years after wildfires relative to corresponding unburned watersheds, but no such difference was found after prescribed burns. These responses are consistent with less altered N biogeochemistry after prescribed burns relative to wildfire. We concluded that δ15N values in terrestrial and aquatic plants and streamwater nitrate concentrations after fire can be useful indicators of the magnitude and duration of fire effects and the fate of

  3. Auto-inducing media for uniform isotope labeling of proteins with {sup 15}N, {sup 13}C and {sup 2}H

    Energy Technology Data Exchange (ETDEWEB)

    Guthertz, Nicolas [Institute of Cancer Research, Division of Structural Biology (United Kingdom); Klopp, Julia; Winterhalter, Aurélie; Fernández, César; Gossert, Alvar D., E-mail: alvar.gossert@novartis.com [Novartis Institutes for BioMedical Research (Switzerland)

    2015-06-15

    Auto-inducing media for protein expression offer many advantages like robust reproducibility, high yields of soluble protein and much reduced workload. Here, an auto-inducing medium for uniform isotope labelling of proteins with {sup 15}N, {sup 13}C and/or {sup 2}H in E. coli is presented. So far, auto-inducing media have not found widespread application in the NMR field, because of the prohibitively high cost of labeled lactose, which is an essential ingredient of such media. Here, we propose using lactose that is only selectively labeled on the glucose moiety. It can be synthesized from inexpensive and readily available substrates: labeled glucose and unlabeled activated galactose. With this approach, uniformly isotope labeled proteins were expressed in unattended auto-inducing cultures with incorporation of {sup 13}C, {sup 15}N of 96.6 % and {sup 2}H, {sup 15}N of 98.8 %. With the present protocol, the NMR community could profit from the many advantages that auto-inducing media offer.

  4. Efficient 13C/15N double labeling of the avirulence protein AVR4 in a methanol-utilizing strain (Mut+) of Pichia pastoris

    Energy Technology Data Exchange (ETDEWEB)

    Burg, Harrold A. van den [Wageningen University, Laboratory of Biochemistry (Netherlands); Wit, Pierre J.G.M. de [Wageningen University, Laboratory of Phytopathology (Netherlands); Vervoort, Jacques [Wageningen University, Laboratory of Biochemistry (Netherlands)

    2001-07-15

    Cost effective {sup 13}C/{sup 15}N-isotope labeling of the avirulence protein AVR4 (10 kDa) of the fungal tomato pathogen Cladosporium fulvum was achieved with the methylotrophic yeast Pichia pastoris in a fermentor. The {sup 13}C/{sup 15}N-labeled AVR4 protein accumulated to 30 mg/L within 48 h in an initial fermentation volume of only 300 mL, while prolonged optimized overexpressions yielded 126 mg/L. These protein yields were 24-fold higher in a fermentor than in flask cultures. In order to achieve these protein expression levels, we used the methanol-utilizing strain (Mut{sup +}) of Pichia pastoris which has a high growth rate while growing on methanol as the only carbon source. In contrast, the methanol-sensitive strain (Mut{sup S}) could intrinsically yield comparable protein expression levels, but at the expense of additional carbon sources. Although both strains are generally used for heterologous protein expression, we show that the costs for {sup 13}C-isotope labeling can be substantially reduced using the Mut{sup +} strain compared to the Mut{sup S} strain, as no {sup 13}C{sub 3}-glycerol is required during the methanol-induction phase. Finally, nitrogen limitations were precluded for {sup 15}N-labeling by an optimal supply of 10 g/L ({sup 15}NH{sub 4}){sub 2}SO{sub 4} every 24 h.

  5. Efficiency of soil and fertilizer nitrogen in relation to rice variety and application time using sup(15)N labelled fertilizer: Pt. 5. sup(15)N point application in fields

    Energy Technology Data Exchange (ETDEWEB)

    Park, H.; Mok, S.K. (Korea Ginseng and Tobacco Research Inst., Seoul (Republic of Korea)); Seok, J.S. (Office of Rural Development, Suwon (Republic of Korea))

    1982-12-01

    From sup(15)N labelled nitrogen experiments on 13 fields use efficiency by difference method was higher than that by labelling method in 80% of fields tested indicating augmentation of soil nitrogen uptake by fertilizer nitrogen. Both methods showed very similar trend among fields. Sulfur coated urea(SCU) and point application increased fertilization efficiency(yield increment per fertilizer nitrogen applied, Fe) to 23 from 15 of split application through the increase of fertilizer use efficiency from 29(Eu) to 50 but tended to decrease efficiency of absorbed fertilizer nitrogen(yield increment per nitrogen derived from fertilizer, Ef) from 50 to 46. High yielding capacity of Tongil line appears to be attributed to the higher Ef, translocation efficiency and soil nitrogen preference index(soil nitrogen increment in plant per the increment of fertilizer nitrogen in plant, PI). This study confirmed that yield under fertilizer application system depends on Fe which is the multiplication of Eu and Ef and that the improvement of fertilizer management(form, application method and time) increases principally Eu, the limit of which is controlled by Ef that is attributed mainly to varietal characteristics.

  6. In situ 15N labeling experiment reveals different long-term responses to ammonium and nitrate inputs in N-saturated subtropical forest

    Science.gov (United States)

    Liu, Wenjing; Yu, Longfei; Zhang, Ting; Kang, Ronghua; Zhu, Jing; Mulder, Jan; Huang, Yongmei; Duan, Lei

    2017-09-01

    Chronically elevated deposition of reactive nitrogen (N), as ammonium (NH4+) and nitrate (NO3-), in subtropical forests with monsoonal climate has caused widespread N leaching in southern China. So far, little is known about the effect of further increases in N input and changes in the relative proportion of NH4+ and NO3- on turnover rate and fate of atmogenic N. Here we report a 15N tracer experiment in Tieshanping (TSP) forest, SW China, conducted as part of a long-term N fertilization experiment, using NH4NO3 and NaNO3, where effects of a doubling of monthly N inputs were compared. In June 2012, the regular N fertilizers were replaced by their 15N-labeled forms, viz., 15NH4NO3 and Na15NO3, as a single-dose addition. Mass balances of N for the initial 1.5 years following label addition showed that for both treatments, 70% to 80% of the annual N input was leached as NO3-, both at ambient and at double N input rates. This confirms the earlier reported extreme case of N saturation at TSP. The 15N, added as Na15NO3, showed recoveries of about 74% in soil leachates, indicating that NO3- input at TSP is subject to a rapid and nearly quantitative loss through direct leaching as a mobile anion. By contrast, recoveries of 15N in soil leachates of only 33% were found if added as 15NH4NO3. Much of the 15N was immobilized in the soil and to a lesser extent in the vegetation. Thus, immobilization of fresh N input is significantly greater if added as NH4+, than as NO3-.

  7. A technique developed for labeling the green manures (sunnhemp and velvet bean) with {sup 15} N for nitrogen dynamic studies; Tecnica para marcacao dos adubos verdes crotalaria juncea e mucuna-preta com {sup 15} N para estudos de dinamica do nitrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosano, Edmilson Jose [Instituto Agronomico de Campinas, SP (Brazil). Secao de Leguminosas; Trivelin, Paulo Cesar Ocheuze; Muruoka, Takashi [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil)

    1997-07-01

    A technique was developed for labeling the leguminous plant tissue with nitrogen ({sup 15} N) to obtain labelled material for nitrogen dynamic studies. Sunnhemp (crotalaria juncea L.) and velvet beans (Mucuna aterrima, sinonimia Stizolobium aterrimum Piper and Tracy) were grown in pots containing 10 kg of a Red Yellow Podzolic soil, under greenhouse conditions. The rate of 1.2 of nitrogen (ammonium sulphate with 11.37 atom % {sup 15} N) per pot was applied three times. The labelled dried plant material showed 3.177 and 4.337 of atom % {sup 15} N, respectively for velvet beans and sunnhemp. (author)

  8. HN-NCA heteronuclear TOCSY-NH experiment for {sup 1}H{sup N} and {sup 15}N sequential correlations in ({sup 13}C, {sup 15}N) labelled intrinsically disordered proteins

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, Christoph; Goradia, Nishit; Häfner, Sabine [Leibniz Institute for Age Research, Fritz Lipmann Institute, Research Group Biomolecular NMR Spectroscopy (Germany); Herbst, Christian [Ubon Ratchathani University, Department of Physics, Faculty of Science (Thailand); Görlach, Matthias; Ohlenschläger, Oliver; Ramachandran, Ramadurai, E-mail: raman@fli-leibniz.de [Leibniz Institute for Age Research, Fritz Lipmann Institute, Research Group Biomolecular NMR Spectroscopy (Germany)

    2015-10-15

    A simple triple resonance NMR experiment that leads to the correlation of the backbone amide resonances of each amino acid residue ‘i’ with that of residues ‘i−1’ and ‘i+1’ in ({sup 13}C, {sup 15}N) labelled intrinsically disordered proteins (IDPs) is presented. The experimental scheme, {HN-NCA heteronuclear TOCSY-NH}, exploits the favourable relaxation properties of IDPs and the presence of {sup 1}J{sub CαN} and {sup 2}J{sub CαN} couplings to transfer the {sup 15}N{sub x} magnetisation from amino acid residue ‘i’ to adjacent residues via the application of a band-selective {sup 15}N–{sup 13}C{sup α} heteronuclear cross-polarisation sequence of ∼100 ms duration. Employing non-uniform sampling in the indirect dimensions, the efficacy of the approach has been demonstrated by the acquisition of 3D HNN chemical shift correlation spectra of α-synuclein. The experimental performance of the RF pulse sequence has been compared with that of the conventional INEPT-based HN(CA)NH pulse scheme. As the availability of data from both the HCCNH and HNN experiments will make it possible to use the information extracted from one experiment to simplify the analysis of the data of the other and lead to a robust approach for unambiguous backbone and side-chain resonance assignments, a time-saving strategy for the simultaneous collection of HCCNH and HNN data is also described.

  9. Towards fully automated structure-based NMR resonance assignment of 15N-labeled proteins from automatically picked peaks

    KAUST Repository

    Jang, Richard

    2011-03-01

    In NMR resonance assignment, an indispensable step in NMR protein studies, manually processed peaks from both N-labeled and C-labeled spectra are typically used as inputs. However, the use of homologous structures can allow one to use only N-labeled NMR data and avoid the added expense of using C-labeled data. We propose a novel integer programming framework for structure-based backbone resonance assignment using N-labeled data. The core consists of a pair of integer programming models: one for spin system forming and amino acid typing, and the other for backbone resonance assignment. The goal is to perform the assignment directly from spectra without any manual intervention via automatically picked peaks, which are much noisier than manually picked peaks, so methods must be error-tolerant. In the case of semi-automated/manually processed peak data, we compare our system with the Xiong-Pandurangan-Bailey- Kellogg\\'s contact replacement (CR) method, which is the most error-tolerant method for structure-based resonance assignment. Our system, on average, reduces the error rate of the CR method by five folds on their data set. In addition, by using an iterative algorithm, our system has the added capability of using the NOESY data to correct assignment errors due to errors in predicting the amino acid and secondary structure type of each spin system. On a publicly available data set for human ubiquitin, where the typing accuracy is 83%, we achieve 91% accuracy, compared to the 59% accuracy obtained without correcting for such errors. In the case of automatically picked peaks, using assignment information from yeast ubiquitin, we achieve a fully automatic assignment with 97% accuracy. To our knowledge, this is the first system that can achieve fully automatic structure-based assignment directly from spectra. This has implications in NMR protein mutant studies, where the assignment step is repeated for each mutant. © Copyright 2011, Mary Ann Liebert, Inc.

  10. Decomposition of 15N-labelled ryegrass in soils from a long-term field experiment with different manuring strategies

    DEFF Research Database (Denmark)

    Jensen, B.K.; Jensen, E.S.; Magid, J.

    1995-01-01

    The cycling of nitrogen in agroecosystems is influenced by the amount and quality of organic matter applied to soils. The N-mineralization of N-15-labelled ryegrass (Lolium perenne L.) was significantly slightly higher in a soil with long-term application of a high amount of farmyard manure (FYM......) than in soils receiving either mineral fertilizer, a low amount of FYM or no manure. However, in general the decomposition of ryegrass in the selected soils varied only slightly. The microbial decomposition processes differed somewhat in the soil manured with a low amount of FYM from those receiving...

  11. Dynamics of amino acid redistribution in the carnivorous Venus flytrap (Dionaea muscipula) after digestion of 13 C/15 N-labelled prey.

    Science.gov (United States)

    Kruse, J; Gao, P; Eibelmeier, M; Alfarraj, S; Rennenberg, H

    2017-11-01

    Amino acids represent an important component in the diet of the Venus flytrap (Dionaea muscipula), and supply plants with much needed nitrogen resources upon capture of insect prey. Little is known about the significance of prey-derived carbon backbones of amino acids for the success of Dionaea's carnivorous life-style. The present study aimed at characterizing the metabolic fate of 15 N and 13 C in amino acids acquired from double-labeled insect powder. We tracked changes in plant amino acid pools and their δ13 C- and δ15 N-signatures over a period of five weeks after feeding, as affected by contrasting feeding intensity and tissue type (i.e., fed and non-fed traps and attached petioles of Dionaea). Isotope signatures (i.e., δ13 C and δ15 N) of plant amino acid pools were strongly correlated, explaining 60% of observed variation. Residual variation was related to contrasting effects of tissue type, feeding intensity and elapsed time since feeding. Synthesis of nitrogen-rich transport compounds (i.e., amides) during peak time of prey digestion increased 15 N- relative to 13 C- abundances in amino acid pools. After completion of prey digestion, 13 C in amino acid pools was progressively exchanged for newly fixed 12 C. The latter process was most evident for non-fed traps and attached petioles of plants that had received ample insect powder. We argue that prey-derived amino acids contribute to respiratory energy gain and loss of 13 CO2 during conversion into transport compounds (i.e., 2 days after feeding), and that amino-nitrogen helps boost photosynthetic carbon gain later on (i.e., 5 weeks after feeding). © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

  12. Alpine plant community controls on ecosystem N pools under the influence of N deposition using an enriched 15N tracer experiment

    Science.gov (United States)

    Churchill, A. C.; Bowman, W. D.

    2016-12-01

    Plant communities are assemblages of species with unique traits, and by comparing different communities we can infer how those traits affect ecosystem processes. In particular, plant feedbacks affecting the N cycle can drive processing of N in numerous pools within an ecosystem, both as individuals and as a part of the larger community. Global nitrogen (N) deposition rates have increased dramatically since the industrial revolution and an understanding of how plant feedbacks may contribute to ecosystem responses is needed. We used an enriched 15N isotope tracer to compare ecosystem N pools associated with plant processing of N among three alpine plant communities (dry, moist, and wet meadows) with diverse characteristics. We applied NH4NO3 as a fertilizer at two treatment levels, ambient deposition (control) and 30 kg N ha-1 yr-1 (fertilized) and collected measurements of enrichment in ecosystem plant and soil N pools following two growing seasons after our application of the isotopic tracer (fall 2014 and fall 2015). We found that the 15N enrichment (‰) of aboveground plant litter declined in all communities between 2014 and 2015, with greater loss of enrichment in fertilized plots in both the dry and wet meadow communities. This decline between years is expected, as litter is decomposed or if plants translocate N into belowground structures, however these results suggest that increased N deposition promotes plant N leakiness for communities with higher species diversity. Despite this trend, aboveground litter from fertilized plots remained more enriched than controls in both the dry and wet meadow communities, perhaps associated with overall greater capacity of those plant individuals to retain N. For control plots, the 15N enrichment of aboveground plant litter was comparable among the dry and moist communities, but the wet meadow was more enriched relative to the moist meadow. Fertilized plots showed a different pattern of enrichment: moist meadow < dry

  13. Preparation of Uniformly 13C,15N-Labeled Recombinant Human Amylin for Solid-State NMR Investigation

    DEFF Research Database (Denmark)

    Kosicka, Iga; Kristensen, Torsten; Bjerring, Morten

    2014-01-01

    A number of diseases are caused by the formation of amyloid fibrils. Detailed understanding of structural features of amyloid fibers is of great importance for our understanding of disease progression and design of agents for diagnostics or potential prevention of protein aggregation. In lack of ...... and electron microscopy, show toxicity towards human cells, and demonstrate that produced material may form the basis for structure determination using solid-state NMR.......A number of diseases are caused by the formation of amyloid fibrils. Detailed understanding of structural features of amyloid fibers is of great importance for our understanding of disease progression and design of agents for diagnostics or potential prevention of protein aggregation. In lack of 3D...... crystal ordering, solid-state NMR forms the most suited method to determine the structures of the fibrils with atomic resolution. To exploit this potential, large amounts of isotopic-labeled protein need to be obtained through recombinant protein expression. However, expression and purification...

  14. Candidate serum biomarkers for early intestinal cancer using 15N metabolic labeling and quantitative proteomics in the ApcMin/+ mouse.

    Science.gov (United States)

    Ivancic, Melanie M; Huttlin, Edward L; Chen, Xiaodi; Pleiman, Jennifer K; Irving, Amy A; Hegeman, Adrian D; Dove, William F; Sussman, Michael R

    2013-09-06

    Current screening procedures for colorectal cancer are imperfect and highly invasive and result in increased mortality rates due to low compliance. The goal of the experiments reported herein is to identify potential blood-based biomarkers indicative of early stage intestinal cancers using the ApcMin/+ mouse model of intestinal cancer as an experimental system. Serum proteins from tumor-bearing ApcMin/+ mice were quantitatively compared to tumor-free Apc+/+ wild-type mice via in anima metabolic labeling with 14N/15N-labeled Spirulina algae and an LTQ Orbitrap mass spectrometer. Out of 1116 total serum proteins quantified, this study identified 40 that were differentially expressed and correlated with the increase in intestinal neoplasms. A subset of these differentially expressed proteins underwent a secondary quantitative screen using selected reaction monitoring-mass spectrometry with stable isotope-labeled peptides. Using both quantitative techniques, we identified MGAM and COL1A1 as downregulated and ITIH3 and F5 as upregulated in serum. All but COL1A1 were similarly differentially expressed in the mRNA of neoplastic colonic tissues of ApcMin/+ mice compared to normal wild-type tissue. These differentially expressed proteins identified in the ApcMin/+ mouse model have provided a set of candidate biomarkers for future validation screens in humans.

  15. hnCOcaNH and hncoCANH pulse sequences for rapid and unambiguous backbone assignment in (13C, 15N) labeled proteins.

    Science.gov (United States)

    Kumar, Dinesh; Reddy, Jithender G; Hosur, Ramakrishna V

    2010-09-01

    Time-saving in data acquisition is a major thrust of NMR pulse sequence development in the context of structural proteomics research. The conventional HNCA and HN(CA)CO pulse sequences, routinely used for sequential backbone assignment, have the limitation that they cannot distinguish inter- and intra-residue correlations. In order to remove this ambiguity, one has to record HNCO and HN(CO)CA or sequential HNCA experiments which provide unambiguous information of sequential correlations. However, this almost doubles the experimental time. Besides, they require repeated scanning through the (15)N planes to search for the matching peaks along the carbon dimension. In this background, we present here two pulse sequences, termed as hncoCANH and hnCOcaNH that lead to spectra equivalent to HNCA and HN(CA)CO spectra, respectively, but with direct distinction of inter- and intra-residue peaks; these occur with opposite signs in the new experiments. The two pulse sequences have been derived by simple modification of the previously described HN(C)N pulse sequence [Panchal et al., J. Biomol. NMR 20 (2001) 135-147] to frequency-label (13)C(alpha) or (13)C' instead of (15)N during the t(1) period. Like HN(C)N, these spectra also exhibit special patterns of self and sequential peaks around glycines and prolines, which enable direct identification of certain triplets of residues and thus provide internal checks during the sequential assignment walk. The spectra enable rapid and unambiguous assignment of H(N), (15)N and (13)C(alpha) (or (13)C') in a single experiment, and thus would be of great value in high-throughput structural proteomics. (c) 2010. Published by Elsevier Inc.

  16. Efficiency of soil and fertilizer nitrogen in relation to rice variety and application time using sup(15)N labelled fertilizer: Pt. 4. Pot experiment for split application of sup(15)N-urea

    Energy Technology Data Exchange (ETDEWEB)

    Park, H. (Korea Ginseng and Tobacco Research Inst., Seoul (Republic of Korea)); Kim, U.J. (Office of Rural Development, Suwon (Republic of Korea))

    1982-09-01

    Top-dressing pot experiment with sup(15)N urea was carried out by using three varieties. Two-split application was much better for Tongil line than 4-split. Fertilization efficiency(Fe), use efficiency(Eu) and absorbed fertilizer nitrogen efficiency (Ef) were much greater in 2-split than in 4-split. The order of Fe followed that of Ef. Grain yield and sup(15)N excess % among plant parts suggest that Tongil line uptakes fertilizer nitrogen much in early stage and retranslocated well later. The order of soil nitrogen increment in plant per fertilizer nitrogen in plant (..delta..Ns/Nf) might be an index of soil nitrogen use efficiency due to fertilizer.

  17. Use of a novel nitrification inhibitor to reduce nitrous oxide emission from (15)N-labelled dairy slurry injected into soil.

    Science.gov (United States)

    Dittert, K; Bol, R; King, R; Chadwick, D; Hatch, D

    2001-01-01

    Recent recommendations for environmentally sound use of liquid animal manure often include injection of slurry into soil. Two of the most important undesired side effects, ammonia (NH(3)) volatilisation and odour emissions, are usually significantly reduced by slurry injection. On the other hand, because of the higher amount of nitrogen (N) remaining in soil, the risk of nitrate (NO(3)(-)) leaching and nitrous oxide (N(2)O) emissions is increased. Thus, the reduction of local effects caused by NH(3) deposition, e.g. N enrichment and soil acidification, may be at the cost of large-scale effects such as ozone depletion and global warming as a result of emitted N(2)O. In this context, nitrification inhibitors can contribute significantly to a reduction in NO(3)(-) leaching and N(2)O production. A field experiment was carried out at IGER, North Wyke, which aimed to evaluate the effect of the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP/ENTEC). For this experiment, (15)N enriched dairy slurry was used and the isotopic label in soil N as well as in N(2)O were studied. After slurry injection into the grassland soil in August 2000, the major emissions of N(2)O occurred during the first ten days. As expected, high N(2)O emission rates and (15)N content of the emissions were concentrated on the slurry injection slots, showing a steep decrease towards the untreated centre-point between slurry injection slots. The nitrification inhibitor DMPP proved to be very efficient in reducing N(2)O emissions. At a rate of 2 kg DMPP ha(-1), the total amount of N(2)O emitted was reduced by 32%, when compared with slurry injection without DMPP. The isotopic label of the emitted N(2)O showed that during the 22-day experimental period, emissions from the slurry N pool were strongly reduced by DMPP from 0.93 kg N(2)O-N ha(-1) (-DMPP) to 0.50 kg N(2)O-N ha(-1) (+DMPP), while only a minor effect on emissions from the soil N pool was observed (0.69 to 0.60 kg N(2)O-N ha(-1

  18. Combined 15N-Labeling and TandemMOAC Quantifies Phosphorylation of MAP Kinase Substrates Downstream of MKK7 in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Nicola V. Huck

    2017-12-01

    Full Text Available Reversible protein phosphorylation is a widespread posttranslational modification that plays a key role in eukaryotic signal transduction. Due to the dynamics of protein abundance, low stoichiometry and transient nature of protein phosphorylation, the detection and accurate quantification of substrate phosphorylation by protein kinases remains a challenge in phosphoproteome research. Here, we combine tandem metal-oxide affinity chromatography (tandemMOAC with stable isotope 15N metabolic labeling for the measurement and accurate quantification of low abundant, transiently phosphorylated peptides by mass spectrometry. Since tandemMOAC is not biased toward the enrichment of acidophilic, basophilic, or proline-directed kinase substrates, the method is applicable to identify targets of all these three types of protein kinases. The MKK7-MPK3/6 module, for example, is involved in the regulation of plant development and plant basal and systemic immune responses, but little is known about downstream cascade components. Using our here described phosphoproteomics approach we identified several MPK substrates downstream of the MKK7-MPK3/6 phosphorylation cascade in Arabidopsis. The identification and validation of dynamin-related protein 2 as a novel phosphorylation substrate of the MKK7-MPK3/6 module establishes a novel link between MPK signaling and clathrin-mediated vesicle trafficking.

  19. Effect of {sup 15}n-labeled hairy vetch and nitrogen fertilization on maize nutrition and yield under no-tillage

    Energy Technology Data Exchange (ETDEWEB)

    Almeida Acosta, Jose Alan de [Drakkar Solos, Santa Maria, RS (Brazil); Amado, Telmo Jorge Carneiro; Silva, Leandro Souza da, E-mail: tamado@smail.ufsm.b, E-mail: leandro@smail.ufsm.b [Universidade Federal de Santa Maria (UFSM), RS (Brazil). Soil Dept.; Neergaard, Andreas de; Vinther, Mads, E-mail: adn@life.ku.d [University of Copenhagen (Denmark); Silveira Nicoloso, Rodrigo da, E-mail: rodrigo.nicoloso@cnpsa.embrapa.b [Embrapa Swine and Poultry, Concordia, SC (Brazil)

    2011-07-15

    This study evaluated the effect of hairy vetch (Vicia villosa Roth) as cover crop on maize nutrition and yield under no tillage using isotope techniques. For this purpose, three experiments were carried out: quantification of biological nitrogen fixation (BNF) in hairy vetch; estimation of the N release rate from hairy vetch residues on the soil surface; quantification of {sup 15}N recovery by maize from labeled hairy vetch under three rates of mineral N fertilization. This two year field experiment was conducted on a sandy Acrisol (FAO soil classification) or Argissolo Vermelho distrofico arenico (Brazilian Soil Classification), at a mean annual temperature of 18 deg C and mean annual rainfall of 1686 mm. The experiment was arranged in a double split-plot factorial design with three replications. Two levels of hairy vetch residue (50 and 100 % of the aboveground biomass production) were distributed on the surface of the main plots (5 x 12 m). Maize in the sub-plots (5 x 4 m) was fertilized with three N rates (0, 60, and 120 kg ha{sup -1} N), with urea as N source. The hairy vetch-derived N recovered by maize was evaluated in microplots (1.8 x 2.2 m). The BFN of hairy vetch was on average 72.4 %, which represents an annual input of 130 kg ha{sup -1} of atmospheric N. The N release from hairy vetch residues was fast, with a release of about 90 % of total N within the first four weeks after cover crop management and soil residue application. The recovery of hairy vetch {sup 15}N by maize was low, with an average of 12.3 % at harvest. Although hairy vetch was not directly the main source of maize N nutrition, the crop yield reached 8.2 Mg ha{sup -1}, without mineral fertilization. There was an apparent synergism between hairy vetch residue application and the mineral N fertilization rate of 60 kg ha{sup -1}, confirming the benefits of the combination of organic and inorganic N sources for maize under no tillage. (author)

  20. Marcação de fitomassa de cana-de-açúcar com aplicação de solução de uréia marcada com15N Sugarcane phytomass labeling with application of 15N-urea solution

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Faroni

    2007-06-01

    Full Text Available O objetivo deste trabalho foi comparar três métodos de aplicação de solução de uréia marcada com15N (15N-uréia : pulverização foliar, injeção na base do colmo e imersão radicular, a fim de se definir qual seria o mais eficiente na marcação de fitomassa de cana-de-açúcar. O experimento foi instalado na Estação Experimental Apta - Pólo Regional Centro Sul, em Piracicaba, SP. A cana-de-açúcar, variedade SP80 3280, foi plantada em vasos preenchidos com aproximadamente 120 dm³ de Neossolo Quartzarênico de textura arenosa. O delineamento experimental foi inteiramente casualizado, com quatro repetições. A fitomassa de cana-de-açúcar dos três tratamentos, no 11º mês de desenvolvimento, não diferiu estatisticamente, e suas abundâncias de 15N foram superiores à natural, tendo-se verificado a seguinte ordem decrescente de marcação com 15N: parte aérea > rizoma > rizomas+raízes na camada de 0,0-0,2 m > raízes na camada de 0,2-0,4 m > raízes em profundidade maior que 0,4 m. Entre os métodos de aplicação de 15N-uréia, a injeção na base de colmos é o de mais fácil execução, o mais efetivo na marcação da fitomassa e o que apresentou a maior recuperação do traçador (96%. A aplicação foliar é comparável à injeção, somente na marcação e na recuperação do traçador no sistema radicular.The objective of this research was to compare three methods of 15N-urea solutions application: spray on leaf, injection in the plant base stem and root immersion, in order to define the most efficient labeling sugarcane phytomass with 15N method. The experiment was carried out at APTA - Pólo Regional Centro Sul, in Piracicaba, SP, Brazil, and the sugarcane variety SP80 3280 was planted in pots filled out with approximately 120 dm³ of a Typic Quartzipsamment soil. The experiment was conducted in a completely randomized design with four replicates. There were no difference between the methods in the plant parts dry

  1. CLEAR Landscape Change Module: No Increased Restoration and Protection, UTM Zone 15N NAD83, Coastal Louisiana Ecosystem Assessment and Restoration (2007), [CLEAR_Output_NIA_012307_final

    Data.gov (United States)

    Louisiana Geographic Information Center — The Coastal Louisiana Ecosystem Assessment and Restoration (CLEAR) Framework is an integrated ecosystem forecasting system, designed to simulate ecological change...

  2. Application of the 15N gas-flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    Science.gov (United States)

    Sgouridis, Fotis; Stott, Andrew; Ullah, Sami

    2016-03-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilized agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in-house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps and a copper-based reduction furnace, and allows the analysis of small gas injection volumes (4 µL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Preconcentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N gas-flux method was adapted for application in natural and semi-natural land use types (peatlands, forests, and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. The minimum detectable flux rates were 4 µg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. Total denitrification rates measured by the acetylene inhibition technique in the same land use types correlated (r = 0.58) with the denitrification rates measured under the 15N gas-flux method, but were underestimated by a factor of 4, and this was partially attributed to the incomplete inhibition of N2O reduction to N2, under a relatively high soil moisture content, and/or the catalytic NO decomposition in the presence of acetylene. Even though relatively robust for in situ denitrification measurements, methodological

  3. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to denitrification in natural and semi-natural terrestrial ecosystems and comparison with the acetylene inhibition technique

    Science.gov (United States)

    Sgouridis, F.; Ullah, S.; Stott, A.

    2015-08-01

    Soil denitrification is considered the most un-constrained process in the global N cycle due to uncertain in situ N2 flux measurements, particularly in natural and semi-natural terrestrial ecosystems. 15N tracer approaches can provide in situ measurements of both N2 and N2O simultaneously, but their use has been limited to fertilised agro-ecosystems due to the need for large 15N additions in order to detect 15N2 production against the high atmospheric N2. For 15N-N2 analyses, we have used an "in house" laboratory designed and manufactured N2 preparation instrument which can be interfaced to any commercial continuous flow isotope ratio mass spectrometer (CF-IRMS). The N2 prep unit has gas purification steps, a copper based reduction furnace, and allows the analysis of small gas injection volumes (4 μL) for 15N-N2 analysis. For the analysis of N2O, an automated Tracegas Pre-concentrator (Isoprime Ltd) coupled to an IRMS was used to measure the 15N-N2O (4 mL gas injection volume). Consequently, the coefficient of variation for the determination of isotope ratios for N2 in air and in standard N2O (0.5 ppm) was better than 0.5 %. The 15N Gas-Flux method was adapted for application in natural and semi-natural land use types (peatlands, forests and grasslands) by lowering the 15N tracer application rate to 0.04-0.5 kg 15N ha-1. For our chamber design (volume / surface = 8:1) and a 20 h incubation period, the minimum detectable flux rates were 4 μg N m-2 h-1 and 0.2 ng N m-2 h-1 for the N2 and N2O fluxes respectively. The N2 flux ranged between 2.4 and 416.6 μg N m-2 h-1, and the grassland soils showed on average 3 and 14 times higher denitrification rates than the woodland and organic soils respectively. The N2O flux was on average 20 to 200 times lower than the N2 flux, while the denitrification product ratio (N2O/N2 + N2O) was low, ranging between 0.03 and 13 %. Total denitrification rates measured by the acetylene inhibition technique under the same field conditions

  4. Revisiting the use of δ15N in meso-scale studies of marine food webs by considering spatio-temporal variations in stable isotopic signatures - The case of an open ecosystem: The Bay of Biscay (North-East Atlantic)

    Science.gov (United States)

    Chouvelon, T.; Spitz, J.; Caurant, F.; Mèndez-Fernandez, P.; Chappuis, A.; Laugier, F.; Le Goff, E.; Bustamante, P.

    2012-08-01

    Most of the recent framework directives and environmental policies argue for the development and the use of indicators - notably trophodynamic indicators - that should be able to follow ecosystems' evolution in space and time, particularly under anthropogenic perturbations. In the last decades, the use of stable carbon and nitrogen isotopes ratios has increased exponentially, particularly in studies of marine ecosystems' trophic structure and functioning. This method is principally based on the assumption that the isotopic composition of a consumer directly reflects that of its food. Nevertheless, few studies have attempted to define the limits of this tool, before using it and drawing ecological conclusions from isotopic analysis. This study aimed to assess the importance of considering spatio-temporal variations in isotopic signatures of consumers when using δ13C and especially δ15N values in open ecosystems with complex food webs, using the Bay of Biscay (North-East Atlantic) as a case study. To this end, more than 140 species from this marine ecosystem were analysed for the isotopic signatures in their muscle tissue. They were sampled from coastal to oceanic and deep-sea areas and at different latitudes, to evaluate spatial variations of isotopic signatures. Selected species were also sampled over several years and in two seasons to account for inter-annual and seasonal variations. In the Bay of Biscay temperate ecosystem, which is subject to both coastal and oceanic influences - two main river inputs and upwelling areas - , δ13C and δ15N values significantly decreased from inshore to offshore species, and to a lesser extent from benthic to pelagic organisms. River discharges appeared to be the first factor influencing δ13C and δ15N values in consumers. From the important spatial variations detected in δ15N values in particular, we suggest that in such contrasted ecosystem, nitrogen isotopic ratios may also be revisited as an indicator of the feeding

  5. Biomass production of site selective {sup 13}C/{sup 15}N nucleotides using wild type and a transketolase E. coli mutant for labeling RNA for high resolution NMR

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Chandar S.; Luo Yiling; Chen Bin; Eldho, Nadukkudy V.; Dayie, T. Kwaku, E-mail: dayie@umd.edu [Center for Biomolecular Structure and Organization, University of Maryland, Department of Chemistry and Biochemistry (United States)

    2012-02-15

    Characterization of the structure and dynamics of nucleic acids by NMR benefits significantly from position specifically labeled nucleotides. Here an E. coli strain deficient in the transketolase gene (tktA) and grown on glucose that is labeled at different carbon sites is shown to facilitate cost-effective and large scale production of useful nucleotides. These nucleotides are site specifically labeled in C1 Prime and C5 Prime with minimal scrambling within the ribose ring. To demonstrate the utility of this labeling approach, the new site-specific labeled and the uniformly labeled nucleotides were used to synthesize a 36-nt RNA containing the catalytically essential domain 5 (D5) of the brown algae group II intron self-splicing ribozyme. The D5 RNA was used in binding and relaxation studies probed by NMR spectroscopy. Key nucleotides in the D5 RNA that are implicated in binding Mg{sup 2+} ions are well resolved. As a result, spectra obtained using selectively labeled nucleotides have higher signal-to-noise ratio compared to those obtained using uniformly labeled nucleotides. Thus, compared to the uniformly {sup 13}C/{sup 15}N-labeled nucleotides, these specifically labeled nucleotides eliminate the extensive {sup 13}C-{sup 13}C coupling within the nitrogenous base and ribose ring, give rise to less crowded and more resolved NMR spectra, and accurate relaxation rates without the need for constant-time or band-selective decoupled NMR experiments. These position selective labeled nucleotides should, therefore, find wide use in NMR analysis of biologically interesting RNA molecules.

  6. The fate of fresh and stored 15N-labelled sheep urine and urea applied to a sandy and a sandy loam soil using different application strategies

    DEFF Research Database (Denmark)

    Sørensen, P.; Jensen, E.S.

    1996-01-01

    The fate of nitrogen from N-15-labelled sheep urine and urea applied to two soils was studied under field conditions. Labelled and stored urine equivalent to 204 kg N ha(-1) was either incorporated in soil or applied to the soil surface prior to sowing of Italian ryegrass (Lolium multiflorum L.),...... mineralized in the sandy loam soil, when urine was applied prior to sowing. Thus, the fertilizer effect of urine N may be significantly lower than that of urea N on fine-textured soils, even when gaseous losses of urine N are negligible.......The fate of nitrogen from N-15-labelled sheep urine and urea applied to two soils was studied under field conditions. Labelled and stored urine equivalent to 204 kg N ha(-1) was either incorporated in soil or applied to the soil surface prior to sowing of Italian ryegrass (Lolium multiflorum L.......), or it was applied to ryegrass one month after sowing. In a sandy loam soil, 62% of the incorporated urine N and 78% of the incorporated urea N was recovered in three cuts of herbage after 5 months. In a sandy soil, 51-53% of the labelled N was recovered in the herbage and the distribution of labelled N in plant...

  7. Combining combing and secondary ion mass spectrometry to study DNA on chips using 13C and 15N labeling [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Armelle Cabin-Flaman

    2016-06-01

    Full Text Available Dynamic secondary ion mass spectrometry (D-SIMS imaging of combed DNA – the combing, imaging by SIMS or CIS method – has been developed previously using a standard NanoSIMS 50 to reveal, on the 50 nm scale, individual DNA fibers labeled with different, non-radioactive isotopes in vivo and to quantify these isotopes. This makes CIS especially suitable for determining the times, places and rates of DNA synthesis as well as the detection of the fine-scale re-arrangements of DNA and of molecules associated with combed DNA fibers. Here, we show how CIS may be extended to 13C-labeling via the detection and quantification of the 13C14N- recombinant ion and the use of the 13C:12C ratio, we discuss how CIS might permit three successive labels, and we suggest ideas that might be explored using CIS.

  8. Stabilization and plant uptake of N from 15N-labelled pea residue 16.5 years after incorporation in soil

    DEFF Research Database (Denmark)

    Laberge, G.; Ambus, P.; Hauggaard-Nielsen, H.

    2006-01-01

    The decline of N from N-15-labelled mature pea residues was followed in unplanted soil over 16.5 yr. Eight years after residue incorporation, 24% of the residue N-15 input was still present in the soil and, after 16.5 yr, 16% of the residue N-15 input remained. A double exponential model...... successfully described the decay of N from N-15-labelled pea residues. The total residual N-15 declined with average decay constants of 1.45 yr(-1) for the 30 d to 1 yr period and of 0.07 yr(-1) for the 1-16 yr period. Sixteen years following incorporation of the residues, indicator plants growing in residues......-amended soils were obtaining 1.7% of their N from residue N. This is, to our knowledge, the longest study on decay of N in soils from N-15-labelled crop residues. The current study thus provides a unique data set for our empirical understanding of N-dynamics in agricultural systems, which is a prerequisite...

  9. Plasma free amino acid kinetics in rainbow trout (Oncorhynchus mykiss) using a bolus injection of 15N-labeled amino acids.

    Science.gov (United States)

    Robinson, Jacob William; Yanke, Dan; Mirza, Jeff; Ballantyne, James Stuart

    2011-02-01

    To gain insight into the metabolic design of the amino acid carrier systems in fish, we injected a bolus of (15)N amino acids into the dorsal aorta in mature rainbow trout (Oncorhynchus mykiss). The plasma kinetic parameters including concentration, pool size, rate of disappearance (R(d)), half-life and turnover rate were determined for 15 amino acids. When corrected for metabolic rate, the R(d) values obtained for trout for most amino acids were largely comparable to human values, with the exception of glutamine (which was lower) and threonine (which was higher). R(d) values ranged from 0.9 μmol 100 g(-1) h(-1) (lysine) to 22.1 μmol 100 g(-1) h(-1) (threonine) with most values falling between 2 and 6 μmol 100 g(-1) h(-1). There was a significant correlation between R(d) and the molar proportion of amino acids in rainbow trout whole body protein hydrolysate. Other kinetic parameters did not correlate significantly with whole body amino acid composition. This indicates that an important design feature of the plasma-free amino acids system involves proportional delivery of amino acids to tissues for protein synthesis.

  10. Ecotoxicity of cadmium in a soil collembolan-predatory mite food chain: Can we use the (15)N labeled litter addition method to assess soil functional change?

    Science.gov (United States)

    Zhu, Dong; Ke, Xin; Wu, Longhua; Li, Zhu; Christie, Peter; Luo, Yongming

    2016-12-01

    Effects of cadmium (Cd) on predator-prey relationships and soil ecological function are poorly understood and there are few methods available to measure soil functional change. Thus, we structured a soil-dwelling food chain containing the predatory mite Hypoaspis aculeifer and its collembolan prey Folsomia candida to study the effects of Cd exposure for eight weeks in a spiked soil aged for five years. The (15)N labeled litter was added as food to analyze the change in nitrogen (N) transfer content. H. aculeifer reproduction and growth and the survival and reproduction of F. candida were all negatively affected by Cd exposure, and H. aculeifer reproduction was the most sensitive parameter. The sensitivity responses of F. candida and H. aculeifer were different from those using the previous single species test. The results suggest that predator-prey interactions might influence the toxicity of Cd by predation and food restriction. Cadmium lethal body concentrations of adults and juveniles of F. candida and H. aculeifer juveniles were 500-600, 180-270 and 8-10 μg g(-1), respectively. The content of N transfer from litter to animals in the food chain decreased significantly with increasing soil Cd concentration between 100 and 400 mg kg(-1). The results suggest that the (15)N labeled litter addition method is potentially useful for quantitative assessment of soil functional change for further risk assessment purposes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Multi-Isotopic (δ2H, δ13C, δ15N) Tracing of Molt Origin for Red-Winged Blackbirds Associated with Agro-Ecosystems.

    Science.gov (United States)

    Werner, Scott J; Hobson, Keith A; Van Wilgenburg, Steven L; Fischer, Justin W

    2016-01-01

    We analyzed stable-hydrogen (δ2H), carbon (δ13C) and nitrogen (δ 15N) isotope ratios in feathers to better understand the molt origin and food habits of Red-winged Blackbirds (Agelaius phoeniceus) near sunflower production in the Upper Midwest and rice production in the Mid-South of the United States. Outer primary feathers were used from 661 after-second-year (ASY) male blackbirds collected in Minnesota, Montana, North Dakota and South Dakota (spring collection), and Arkansas, Louisiana, Mississippi, Missouri and Texas (winter collection). The best-fit model indicated that the combination of feather δ2H, δ13C and δ15N best predicted the state of sample collections and thus supported the use of this approach for tracing molt origins in Red-winged Blackbirds. When considering only birds collected in spring, 56% of birds were classified to their collection state on the basis of δ2H and δ13C alone. We then developed feather isoscapes for δ13C based upon these data and for δ2H based upon continental patterns of δ2H in precipitation. We used 81 birds collected at the ten independent sites for model validation. The spatially-explicit assignment of these 81 birds to the δ2H isoscape resulted in relatively high rates (~77%) of accurate assignment to collection states. We also modeled the spatial extent of C3 (e.g. rice, sunflower) and C4 (corn, millet, sorghum) agricultural crops grown throughout the Upper Midwest and Mid-South United States to predict the relative use of C3- versus C4-based foodwebs among sampled blackbirds. Estimates of C3 inputs to diet ranged from 50% in Arkansas to 27% in Minnesota. As a novel contribution to blackbird conservation and management, we demonstrate how such feather isoscapes can be used to predict the molt origin and interstate movements of migratory blackbirds for subsequent investigations of breeding biology (e.g. sex-specific philopatry), agricultural depredation, feeding ecology, physiology of migration and sensitivity to

  12. Multi-Isotopic (δ2H, δ13C, δ15N Tracing of Molt Origin for Red-Winged Blackbirds Associated with Agro-Ecosystems.

    Directory of Open Access Journals (Sweden)

    Scott J Werner

    Full Text Available We analyzed stable-hydrogen (δ2H, carbon (δ13C and nitrogen (δ 15N isotope ratios in feathers to better understand the molt origin and food habits of Red-winged Blackbirds (Agelaius phoeniceus near sunflower production in the Upper Midwest and rice production in the Mid-South of the United States. Outer primary feathers were used from 661 after-second-year (ASY male blackbirds collected in Minnesota, Montana, North Dakota and South Dakota (spring collection, and Arkansas, Louisiana, Mississippi, Missouri and Texas (winter collection. The best-fit model indicated that the combination of feather δ2H, δ13C and δ15N best predicted the state of sample collections and thus supported the use of this approach for tracing molt origins in Red-winged Blackbirds. When considering only birds collected in spring, 56% of birds were classified to their collection state on the basis of δ2H and δ13C alone. We then developed feather isoscapes for δ13C based upon these data and for δ2H based upon continental patterns of δ2H in precipitation. We used 81 birds collected at the ten independent sites for model validation. The spatially-explicit assignment of these 81 birds to the δ2H isoscape resulted in relatively high rates (~77% of accurate assignment to collection states. We also modeled the spatial extent of C3 (e.g. rice, sunflower and C4 (corn, millet, sorghum agricultural crops grown throughout the Upper Midwest and Mid-South United States to predict the relative use of C3- versus C4-based foodwebs among sampled blackbirds. Estimates of C3 inputs to diet ranged from 50% in Arkansas to 27% in Minnesota. As a novel contribution to blackbird conservation and management, we demonstrate how such feather isoscapes can be used to predict the molt origin and interstate movements of migratory blackbirds for subsequent investigations of breeding biology (e.g. sex-specific philopatry, agricultural depredation, feeding ecology, physiology of migration and

  13. {sup 15}N and {sup 13}C- SOFAST-HMQC editing enhances 3D-NOESY sensitivity in highly deuterated, selectively [{sup 1}H,{sup 13}C]-labeled proteins

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Paolo, E-mail: rossip@umn.edu; Xia, Youlin; Khanra, Nandish; Veglia, Gianluigi, E-mail: vegli001@umn.edu; Kalodimos, Charalampos G., E-mail: ckalodim@umn.edu [University of Minnesota, Department of Biochemistry, Molecular Biology and Biophysics (United States)

    2016-12-15

    The ongoing NMR method development effort strives for high quality multidimensional data with reduced collection time. Here, we apply ‘SOFAST-HMQC’ to frequency editing in 3D NOESY experiments and demonstrate the sensitivity benefits using highly deuterated and {sup 15}N, methyl labeled samples in H{sub 2}O. The experiments benefit from a combination of selective T{sub 1} relaxation (or L-optimized effect), from Ernst angle optimization and, in certain types of experiments, from using the mixing time for both NOE buildup and magnetization recovery. This effect enhances sensitivity by up to 2.4× at fast pulsing versus reference HMQC sequences of same overall length and water suppression characteristics. Representative experiments designed to address interesting protein NMR challenges are detailed. Editing capabilities are exploited with heteronuclear {sup 15}N,{sup 13}C-edited, or with diagonal-free {sup 13}C aromatic/methyl-resolved 3D-SOFAST-HMQC–NOESY–HMQC. The latter experiment is used here to elucidate the methyl-aromatic NOE network in the hydrophobic core of the 19 kDa FliT-FliJ flagellar protein complex. Incorporation of fast pulsing to reference experiments such as 3D-NOESY–HMQC boosts digital resolution, simplifies the process of NOE assignment and helps to automate protein structure determination.

  14. Nitrogen input 15N signatures are reflected in plant 15N natural abundances in subtropical forests in China

    Science.gov (United States)

    Abdisa Gurmesa, Geshere; Lu, Xiankai; Gundersen, Per; Fang, Yunting; Mao, Qinggong; Hao, Chen; Mo, Jiangming

    2017-05-01

    Natural abundance of 15N15N) in plants and soils can provide time-integrated information related to nitrogen (N) cycling within ecosystems, but it has not been well tested in warm and humid subtropical forests. In this study, we used ecosystem δ15N to assess effects of increased N deposition on N cycling in an old-growth broad-leaved forest and a secondary pine forest in a high-N-deposition area in southern China. We measured δ15N of inorganic N in input and output fluxes under ambient N deposition, and we measured N concentration (%N) and δ15N of major ecosystem compartments under ambient deposition and after decadal N addition at 50 kg N ha-1yr-1, which has a δ15N of -0.7 ‰. Our results showed that the total inorganic N in deposition was 15N-depleted (-10 ‰) mainly due to high input of strongly 15N-depleted NH4+-N. Plant leaves in both forests were also 15N-depleted (-4 to -6 ‰). The broad-leaved forest had higher plant and soil %N and was more 15N-enriched in most ecosystem compartments relative to the pine forest. Nitrogen addition did not significantly affect %N in the broad-leaved forest, indicating that the ecosystem pools are already N-rich. However, %N was marginally increased in pine leaves and significantly increased in understory vegetation in the pine forest. Soil δ15N was not changed significantly by the N addition in either forest. However, the N addition significantly increased the δ15N of plants toward the 15N signature of the added N, indicating incorporation of added N into plants. Thus, plant δ15N was more sensitive to ecosystem N input manipulation than %N in these subtropical forests. We interpret the depleted δ15N of plants as an imprint from the high and 15N-depleted N deposition that may dominate the effects of fractionation that are observed in most warm and humid forests. Fractionation during the steps of N cycling could explain the difference between negative δ15N in plants and positive δ15N in soils, and the increase

  15. The fate of organic matter in a papyrus (Cyperus papyrus L.) dominated tropical wetland ecosystem in Nyanza Gulf (Lake Victoria, Kenya) inferred from delta13C and delta15N analysis.

    Science.gov (United States)

    Gichuki, John W; Triest, Ludwig; Dehairs, Frank

    2005-12-01

    Papyrus swamps usually form at the interface between river inlet and open lake. From one such wetland ecosystem (the Kibos system located in the Nyanza Gulf, Lake Victoria, Kenya), three sediment cores were recovered using piston corer in order to determine the fate of organic matter derived from papyrus and possible nutrient pathways in this system. The coring represented a transect from the river through the floating papyrus mat to the lake. Two short cores were retrieved from the lake and river. One long core (2 m) was recovered on a floating papyrus mat. The C:N ratio showed similar trends down core from the three locations. This may possibly be due to diagenic processes such as autolysis, dissolution and microbial mineralisation occurring in the sediments. Statistical analysis through one-way ANOVA revealed no significant differences in the C:N ratios between stations. Results of the stable carbon isotope ratios revealed that the delta(13)C of the river and lake samples were persistently more negative than -20 per thousand over the whole profile indicating possible contribution from terrestrial derived carbon. Regarding the floating mat core, the delta(13)C values ranged from -18.99 per thousand on the top of the floating mat but gradually increased to -16.82 per thousand towards the bottom of the core indicating possible contribution of carbon from Cyperus papyrus that has a delta(13)C value of -13.45+/-0.62 per thousand. Statistical analysis through one-way ANOVA revealed significant differences in the delta(13)C values between stations. The stable nitrogen isotope values were highly positive both in the river and in the lake station (delta(15)N > 10 per thousand), indicating possible contamination from sewage wastes. Values in the swamp were less positive suggesting first, the formation of ammonium depleted in (15)N from intense organic matter mineralisation, secondly indicating the delta(15)N signal of papyrus and, finally that nitrogen fixation processes

  16. Fate of leaf-litter N in forest and grassland along a pedo-climatic gradient in south-western Siberia: an in situ 15N-labelling experiment

    Science.gov (United States)

    Brédoire, Félix; Zeller, Bernd; Nikitich, Polina; Barsukov, Pavel A.; Rusalimova, Olga; Bakker, Mark R.; Legout, Arnaud; Bashuk, Alexander; Kayler, Zachary E.; Derrien, Delphine

    2017-04-01

    The suitability of Siberia for agriculture is expected to increase in the next decades due to strong and rapid climatic changes, but little is known on the environmental drivers of soil fertility there, especially nitrogen (N). Plant-available N is mainly derived from litter decomposition. South-western (SW) Siberia is located on the transition between several bioclimatic zones that are predicted to shift and extend along with climate change (steppe, forest-steppe, sub-taiga). The soils of this region are formed on a common loess deposit but they are submitted to different climatic conditions and vegetation cover. In the south of the region, typically in steppe/forest-steppe, soil freezes over winter because of a relatively shallow snow-pack, and water shortages are frequent in summer. In the north, typically in sub-taiga, the soil is barely frozen in winter due to a thick snow-pack and sufficient soil moisture in summer. In this study, we characterized the dynamics of leaf litter decomposition and the transfer of N from leaf litter to the soil and back to plants. Four sites were chosen along a climate gradient (temperature, precipitation and snow depth). At each site, we applied 15N-labelled leaf litter on the soil surface in experimental plots in an aspen (Populus tremula L.) forest and in a grassland. Twice a year during three years, we tracked the 15N derived from the decomposing labelled-litter in the organic layers, in the first 15 cm of the soil, and in above-ground vegetation. Soil temperature and moisture were monitored at a daily timestep over three years and soil water budgets were simulated (BILJOU model, Granier et al. 1999). We observed contrasting patterns in the fate of litter-derived 15N between bioclimatic zones. Over three years, along with faster decay rates, the release of leaf litter-N was faster in sub-taiga than in forest-steppe. As such, higher quantities of 15N were transferred into the soil in sub-taiga. The transfer was also deeper there

  17. NMR studies of active-site properties of human carbonic anhydrase II by using (15) N-labeled 4-methylimidazole as a local probe and histidine hydrogen-bond correlations.

    Science.gov (United States)

    Shenderovich, Ilya G; Lesnichin, Stepan B; Tu, Chingkuang; Silverman, David N; Tolstoy, Peter M; Denisov, Gleb S; Limbach, Hans-Heinrich

    2015-02-09

    By using a combination of liquid and solid-state NMR spectroscopy, (15) N-labeled 4-methylimidazole (4-MI) as a local probe of the environment has been studied: 1) in the polar, wet Freon CDF3 /CDF2 Cl down to 130 K, 2) in water at pH 12, and 3) in solid samples of the mutant H64A of human carbonic anhydrase II (HCA II). In the latter, the active-site His64 residue is replaced by alanine; the catalytic activity is, however, rescued by the presence of 4-MI. For the Freon solution, it is demonstrated that addition of water molecules not only catalyzes proton tautomerism but also lifts its quasidegeneracy. The possible hydrogen-bond clusters formed and the mechanism of the tautomerism are discussed. Information about the imidazole hydrogen-bond geometries is obtained by establishing a correlation between published (1) H and (15) N chemical shifts of the imidazole rings of histidines in proteins. This correlation is useful to distinguish histidines embedded in the interior of proteins and those at the surface, embedded in water. Moreover, evidence is obtained that the hydrogen-bond geometries of His64 in the active site of HCA II and of 4-MI in H64A HCA II are similar. Finally, the degeneracy of the rapid tautomerism of the neutral imidazole ring His64 reported by Shimahara et al. (J. Biol. Chem.- 2007, 282, 9646) can be explained with a wet, polar, nonaqueous active-site conformation in the inward conformation, similar to the properties of 4-MI in the Freon solution. The biological implications for the enzyme mechanism are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Utilization of (15)N-labelled yeast hydrolysate in Lactococcus lactis IL1403 culture indicates co-consumption of peptide-bound and free amino acids with simultaneous efflux of free amino acids.

    Science.gov (United States)

    Kevvai, Kaspar; Kütt, Mary-Liis; Nisamedtinov, Ildar; Paalme, Toomas

    2014-03-01

    Lactococcus lactis subsp. lactis IL1403 was grown in medium containing unlabelled free amino acids and (15)N-labelled yeast hydrolysate to gain insight into the role of peptides as a source of amino acids under conditions where free amino acids are abundant. A mathematical model was composed to estimate the fluxes of free and peptide-derived amino acids into and out of the intracellular amino acid pool. We observed co-consumption of peptides and free amino acids and a considerable efflux of most free amino acids during growth. We did not observe significant differences between the peptide consumption patterns of essential and non-essential amino acids, which suggests that the incorporation of a particular amino acid is more dependent on its availability in a readily assimilated form than the organism's auxotrophy for it. For most amino acids the contribution of peptide-bound forms to the formation of biomass was initially between 30 and 60 % with the remainder originating from free amino acids. During the later stages of fermentation we observed a decrease in the utilization of peptide-bound amino acids, thus indicating that the more readily assimilated peptides are gradually exhausted from the medium during growth.

  19. Compound-specific 15N stable isotope probing of N assimilation by the soil microbial biomass: a new methodological paradigm in soil N cycling

    Science.gov (United States)

    Charteris, A. F.; Knowles, T. D. J.; Michaelides, K.; Evershed, R. P.

    2015-10-01

    A compound-specific nitrogen-15 stable isotope probing (15N-SIP) technique is described which allows investigation of the fate of inorganic- or organic-N amendments to soils. The technique uses gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) to determine the δ15N values of individual amino acids (AAs; determined as N-acetyl, O-isopropyl derivatives) as proxies of biomass protein production. The δ15N values are used together with AA concentrations to quantify N assimilation of 15N-labelled substrates by the soil microbial biomass. The utility of the approach is demonstrated through incubation experiments using inorganic 15N-labelled substrates ammonium (15NH4+) and nitrate (15NO3-) and an organic 15N-labelled substrate, glutamic acid (15N-Glu). Assimilation of all the applied substrates was undetectable based on bulk soil properties, i.e. % total N (% TN), bulk soil N isotope composition and AA concentrations, all of which remained relatively constant throughout the incubation experiments. In contrast, compound-specific AA δ15N values were highly sensitive to N assimilation, providing qualitative and quantitative insights into the cycling and fate of the applied 15N-labelled substrates. The utility of this 15N-AA-SIP technique is considered in relation to other currently available methods for investigating the microbially-mediated assimilation of nitrogenous substrates into the soil organic N pool. This approach will be generally applicable to the study of N cycling in any soil, or indeed, in any complex ecosystem.

  20. Aqueous, Heterogeneous Parahydrogen-Induced 15N Polarization.

    Science.gov (United States)

    Bales, Liana B; Kovtunov, Kirill V; Barskiy, Danila A; Shchepin, Roman V; Coffey, Aaron M; Kovtunova, Larisa M; Bukhtiyarov, Andrey V; Feldman, Matthew A; Bukhtiyarov, Valerii I; Chekmenev, Eduard Y; Koptyug, Igor V; Goodson, Boyd M

    2017-07-20

    The successful transfer of parahydrogen-induced polarization to 15N spins using heterogeneous catalysts in aqueous solutions was demonstrated. Hydrogenation of a synthesized unsaturated 15N-labeled precursor (neurine) with parahydrogen (p-H2) over Rh/TiO2 heterogeneous catalysts yielded a hyperpolarized structural analog of choline. As a result, 15N polarization enhancements of over two orders of magnitude were achieved for the 15N-ethyl trimethyl ammonium ion product in deuterated water at elevated temperatures. Enhanced 15N NMR spectra were successfully acquired at 9.4 T and 0.05 T. Importantly, long hyperpolarization lifetimes were observed at 9.4 T, with a 15N T1 of ~6 min for the product molecules, and the T1 of the deuterated form exceeded 8 min. Taken together, these results show that this approach for generating hyperpolarized species with extended lifetimes in aqueous, biologically compatible solutions is promising for various biomedical applications.

  1. CLEAR Landscape Change Module: Preliminary Draft Coastal Protection and Restoration Authority Master Plan, UTM Zone 15N NAD83, Coastal Louisiana Ecosystem Assessment and Restoration (2007), [clear_ouput_cpra_pdmp_012307

    Data.gov (United States)

    Louisiana Geographic Information Center — The Coastal Louisiana Ecosystem Assessment and Restoration (CLEAR) Framework is an integrated ecosystem forecasting system, designed to simulate ecological change...

  2. Kinetic 15N-isotope effects on algal growth

    Science.gov (United States)

    Andriukonis, Eivydas; Gorokhova, Elena

    2017-03-01

    Stable isotope labeling is a standard technique for tracing material transfer in molecular, ecological and biogeochemical studies. The main assumption in this approach is that the enrichment with a heavy isotope has no effect on the organism metabolism and growth, which is not consistent with current theoretical and empirical knowledge on kinetic isotope effects. Here, we demonstrate profound changes in growth dynamics of the green alga Raphidocelis subcapitata grown in 15N-enriched media. With increasing 15N concentration (0.37 to 50 at%), the lag phase increased, whereas maximal growth rate and total yield decreased; moreover, there was a negative relationship between the growth and the lag phase across the treatments. The latter suggests that a trade-off between growth rate and the ability to adapt to the high 15N environment may exist. Remarkably, the lag-phase response at 3.5 at% 15N was the shortest and deviated from the overall trend, thus providing partial support to the recently proposed Isotopic Resonance hypothesis, which predicts that certain isotopic composition is particularly favorable for living organisms. These findings confirm the occurrence of KIE in isotopically enriched algae and underline the importance of considering these effects when using stable isotope labeling in field and experimental studies.

  3. Nitrogen cycling in a forest stream determined by a 15N tracer addition

    Science.gov (United States)

    Patrick J. Mullholland; Jennifer L. Tank; Diane M. Sanzone; Wilfred M. Wollheim; Bruce J. Peterson; Jackson R. Webster; Judy L. Meyer

    2000-01-01

    Nitrogen uptake and cycling was examined using a six-week tracer addition of 15N-labeled ammonium in early spring in Waer Branch, a first-order deciduous forest stream in eastern Tennessee. Prior to the 15N addition, standing stocks of N were determined for the major biomass compartments. During and after the addition,

  4. Nitrogen Uptake During Fall, Winter and Spring Differs Among Plant Functional Groups in a Subarctic Heath Ecosystem

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Michelsen, Anders; Jonasson, Sven

    2012-01-01

    Nitrogen (N) is a critical resource for plant growth in tundra ecosystems, and species differences in the timing of N uptake may be an important feature regulating community composition and ecosystem productivity. We added 15N-labelled glycine to a subarctic heath tundra dominated by dwarf shrubs......, mosses and graminoids in fall, and investigated its partitioning among ecosystem components at several time points (October, November, April, May, June) through to the following spring/early summer. Soil microbes had acquired 65 ± 7% of the 15N tracer by October, but this pool decreased through winter....... The faster-growing deciduous shrubs did not resume 15N acquisition until after early May indicating that they relied more on nitrogen made available later during the spring/early summer. The graminoids and mosses had no significant increases in 15N tracer recovery or tissue 15N tracer concentrations after...

  5. Plot-size for {sup 15}N-fertilizer recovery studies by tanzania-grass; Tamanho da parcela para estudos de recuperacao de fertilizante-{sup 15}N por capim-tanzania

    Energy Technology Data Exchange (ETDEWEB)

    Martha Junior, Geraldo Bueno [EMBRAPA Cerrados, Planaltina, DF (Brazil)], e-mail: gbmartha@cpac.embrapa.br; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis], e-mail: pcotrive@cena.usp.br; Corsi, Moacyr [Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP), Piracicaba, SP (Brazil). Dept. de Zootecnia], e-mail: moa@esalq.usp.br

    2009-07-01

    The understanding of the N dynamics in pasture ecosystems can be improved by studies using the {sup 15}N tracer technique. However, in these experiments it must be ensured that the lateral movement of the labeled fertilizer does not interfere with the results. In this study the plot-size requirements for {sup 15}N-fertilizer recovery experiments with irrigated Panicum maximum cv. Tanzania was determined. Three grazing intensities (light, moderate and intensive grazing) in the winter, spring and summer seasons were considered. A 1 m{sup 2} plot-size, with a grass tussock in the center, was adequate, irrespective of the grazing intensity or season of the year. Increasing the distance from the area fertilized with {sup 15}N negatively affected the N derived from fertilizer (Npfm) recovered in herbage.The lowest decline in Npfm values were observed for moderate and light grazing intensities. This fact might be explained by the vigorous growth characteristics of these plants. Increasing the grazing intensity decreased the tussock mass and, the smaller the tussock mass, the greater was the dependence on fertilizer nitrogen. (author)

  6. Synthesis of Gemcitabine-13C, 15N2 and Gemcitabine-13C, 15N2 Metabolites

    Directory of Open Access Journals (Sweden)

    ZHU Cheng-gu;YANG Shao-zu;YAN Sheng-wang;FANG Ning-jing;CAI Ding-long;LI Gang

    2014-02-01

    Full Text Available Homemade urea-13C, 15N2 was used to react with 3-methyl acrylonitrile closure to form cytosine-13C, 15N2 (2,which was protected by trimethylsilylation with BSA and condensed with 2-deoxy-2,2-difluoro-D-erythro-pentofuranose-3,5-dibenzoate-1-methanesulfonate at 120 ℃ to afford blocked gemcitabine-13C, 15N2. Hydrolytic removal of the blocking groups of gemcitabine-13C, 15N2 with NaOH gave gemcitabine-13C, 15N2, and its metabolite was obtained by further hydrolytic deamination of gemcitabine-13C, 15N2. The final products were characterized and detected by HPLC, LC-MS and NMR, and confirmed that the chemical purities were higher than 98%, isotopic abundances were 99% 13C, 98% 15N, and they were suitable for drug metabolism studies.

  7. Nutrient Status and δ15N Values in Leaves and Soils: A Cross-Biome Comparison

    Science.gov (United States)

    Mayor, J. R.; Schuur, E. A.; Turner, B. L.; Wright, S. J.

    2011-12-01

    Stable nitrogen (N) isotope ratios (δ15N) are often assumed to provide an integrated measure of multiple nitrogen cycling processes. For instance, shifts in the bioavailability of soil N forms are thought to alter plant δ15N values. Demonstrating this relationship is important as ecosystems undergo anthropogenic disturbances. We evaluated patterns and implied mechanisms of the N cycle using ecosystem δ15N values from 16 plots in boreal black spruce (Picea mariana) forest and lowland wet tropical forest. Fertilizer N and phosphorus (P) was applied annually for five and 11 years prior to measurement of ecosystem δ15N values. Full sun canopy foliage and soil extractable nitrate, ammonium, and dissolved organic N (DON) were sampled in fertilized and control plots and analyzed for δ15N. In boreal forest, N fertilization reduced DON concentrations and caused a depletion of δ15N in foliage and fungal sporocarps. Of four species occurring in all plots in the tropical forest, one (Alseis blackiana) had increased foliar δ15N values following N fertilization, one (Tetragastris panamensis) had increased foliar δ15N values following P fertilization, and one (Oenocarpus mapora) had increased foliar δ15N following N+P fertilization. Surprisingly, soil nitrate in the boreal forest became substantially 15N-enriched under P fertilization, whereas nitrate in the tropical forest soil was enriched only under N or N+P fertilization. Collectively, nitrate enrichment is likely due to enhanced rates of soil denitrification as evidenced by elevated resin extractable soil nitrate concentrations and close correlations between δ15N and δ18O values. On average, foliar δ15N in tropical trees corresponded well with δ15N in soil nitrate in control and P fertilized plots, but was 2-3% more enriched than DON under N and N+P fertilization. In boreal forests, N and N+P fertilization increased foliar N concentration and δ15N values indicating substantial use of applied fertilizer. Taken

  8. Soil processes drive seasonal variation in retention of 15N tracers in a deciduous forest catchment.

    Science.gov (United States)

    Goodale, Christine L; Fredriksen, Guinevere; Weiss, Marissa S; McCalley, K; Sparks, Jed P; Thomas, Steven A

    2015-10-01

    Seasonal patterns of stream nitrate concentration have long been interpreted as demonstrating the central role of plant uptake in regulating stream nitrogen loss from forested catchments. Soil processes are rarely considered as important drivers of these patterns. We examined seasonal variation in N retention in a deciduous forest using three whole-ecosystem 15N tracer additions: in late April (post-snowmelt, pre-leaf-out), late July (mid-growing- season), and late October (end of leaf-fall). We expected that plant 15N uptake would peak in late spring and midsummer, that immobilization in surface litter and soil would peak the following autumn leaf-fall, and that leaching losses would vary inversely with 15N retention. Similar to most other 15N tracer studies, we found that litter and soils dominated ecosystem retention of added 15N. However, 15N recovery in detrital pools varied tremendously by season, with > 90% retention in spring and autumn and sharply reduced 15N retention in late summer. During spring, over half of the 15N retained in soil occurred within one day in the heavy (mineral-associated) soil fraction. During summer, a large decrease in 15N retention one week after addition coincided with increased losses of 15NO3- to soil leachate and seasonal increases in soil and stream NO3- concentrations, although leaching accounted for only a small fraction of the lost 15N (< 0.2%). Uptake of 15N into roots did not vary by season and accounted for < 4% of each tracer addition. Denitrification or other processes that lead to N gas loss may have consumed the rest. These measurements of 15N movement provide strong evidence for the dominant role of soil processes in regulating seasonal N retention and losses in this catchment and perhaps others with similar soils.

  9. Geomorphic control on the δ15N of mountain forests

    Directory of Open Access Journals (Sweden)

    R. G. Hilton

    2013-03-01

    Full Text Available Mountain forests are subject to high rates of physical erosion which can export particulate nitrogen from ecosystems. However, the impact of geomorphic processes on nitrogen budgets remains poorly constrained. We have used the elemental and isotopic composition of soil and plant organic matter to investigate nitrogen cycling in the mountain forest of Taiwan, from 24 sites with distinct geomorphic (topographic slope and climatic (precipitation, temperature characteristics. The organic carbon to nitrogen ratio of soil organic matter decreased with soil 14C age, providing constraint on average rates of nitrogen loss using a mass balance model. Model predictions suggest that present day estimates of nitrogen deposition exceed contemporary and historic nitrogen losses. We found ∼6‰ variability in the stable isotopic composition (δ15N of soil and plants which was not related to soil 14C age or climatic conditions. Instead, δ15N was significantly, negatively correlated with topographic slope. Using the mass balance model, we demonstrate that the correlation can be explained by an increase in nitrogen loss by non-fractioning pathways on steeper slopes, where physical erosion most effectively removes particulate nitrogen. Published data from forests on steep slopes are consistent with the correlation. Based on our dataset and these observations, we hypothesise that variable physical erosion rates can significantly influence soil δ15N, and suggest particulate nitrogen export is a major, yet underappreciated, loss term in the nitrogen budget of mountain forests.

  10. True cooking aroma or artefact. {sup 15}N gives the answer; Veritable arome de cuisson ou artefact. {sup 15}N fournit la reponse

    Energy Technology Data Exchange (ETDEWEB)

    Metro, F.; Boudaud, N.; Dumont, J.P. [INRA, 44 - Nantes (France)

    1994-12-31

    In order to determine the respective contributions of the various nitrous precursor families in aroma preparations, the usually added amino acids were substituted with {sup 15}N isotope labelled homologous components. Results concerning isotope ratios for the volatile fraction nitrous components collected from poultry meat aromatic preparations, are presented. Terminal product labelling appears to allow for a better determination of the substrate and functional additive contributions. 4 figs., 6 refs.

  11. Tracing the cycling and fate of the explosive 2,4,6-trinitrotoluene in coastal marine systems with a stable isotopic tracer, 15N-[TNT

    Science.gov (United States)

    Smith, Richard W.; Vlahos, Penny; Böhlke, John Karl; Ariyarathna, Thivanka; Ballentine, Mark; Cooper, Christopher; Fallis, Stephen; Groshens, Thomas J.; Tobias, Craig

    2015-01-01

    2,4,6-Trinitrotoluene (TNT) has been used as a military explosive for over a hundred years. Contamination concerns have arisen as a result of manufacturing and use on a large scale; however, despite decades of work addressing TNT contamination in the environment, its fate in marine ecosystems is not fully resolved. Here we examine the cycling and fate of TNT in the coastal marine systems by spiking a marine mesocosm containing seawater, sediments, and macrobiota with isotopically labeled TNT (15N-[TNT]), simultaneously monitoring removal, transformation, mineralization, sorption, and biological uptake over a period of 16 days. TNT degradation was rapid, and we observed accumulation of reduced transformation products dissolved in the water column and in pore waters, sorbed to sediments and suspended particulate matter (SPM), and in the tissues of macrobiota. Bulk δ15N analysis of sediments, SPM, and tissues revealed large quantities of 15N beyond that accounted for in identifiable derivatives. TNT-derived N was also found in the dissolved inorganic N (DIN) pool. Using multivariate statistical analysis and a 15N mass balance approach, we identify the major transformation pathways of TNT, including the deamination of reduced TNT derivatives, potentially promoted by sorption to SPM and oxic surface sediments.

  12. Tamanho da parcela para estudos de recuperação de fertilizante-15N por capim-tanzânia Plot-size for 15N-fertilizer recovery studies by tanzania-grass

    Directory of Open Access Journals (Sweden)

    Geraldo Bueno Martha Júnior

    2009-04-01

    Full Text Available O entendimento da dinâmica do N em ecossistemas de pastagens pode ser melhorado por estudos em que se utilize a técnica do traçador 15N. Nesses experimentos, deve-se assegurar que o movimento lateral do traçador não interfira nos resultados. Neste trabalho foram determinadas as exigências quanto ao tamanho da parcela para experimentos com 15N em pastagem irrigada de Panicum maximum cv. Tanzânia. Foram consideradas três intensidades de pastejo (leniente, moderada e intensa em três épocas do ano: inverno, primavera e verão. Parcelas de 1 m², com uma touceira do capim ao centro, foram adequadas, independentemente da intensidade de desfolha ou da época do ano. O aumento na distância da área adubada com 15N influenciou negativamente a quantidade de N proveniente do fertilizante (Npfm recuperado na forragem. As menores taxas de declínio nos valores de Npfm foram observadas para as intensidades de pastejo leniente e moderada; esse fato pode ser explicado pelas características de crescimento vigoroso dessas plantas. O aumento na intensidade de pastejo determinou a redução na massa da touceira: quanto menor a touceira, maior a sua dependência do N do fertilizante.The understanding of the N dynamics in pasture ecosystems can be improved by studies using the 15N tracer technique. However, in these experiments it must be ensured that the lateral movement of the labeled fertilizer does not interfere with the results. In this study the plot-size requirements for 15N-fertilizer recovery experiments with irrigated Panicum maximum cv.Tanzania was determined. Three grazing intensities (light, moderate and intensive grazing in the winter, spring and summer seasons were considered. A 1 m² plot-size, with a grass tussock in the center, was adequate, irrespective of the grazing intensity or season of the year. Increasing the distance from the area fertilized with 15N negatively affected the N derived from fertilizer (Npfm recovered in herbage

  13. 15N Content Reflects Development of Mycorrhizae and Nitrogen Dynamics During Primary Succession

    Science.gov (United States)

    Hobbie, E. A.; Jumpponen, A.

    2004-05-01

    Mycorrhizal fungi are ubiquitous symbionts on terrestrial plants that are particularly important for plant nitrogen nutrition. 15N content appears to be a useful marker of the mycorrhizal role in plant nitrogen supply because of an apparent fractionation against 15N during transfer of nitrogen from mycorrhizal fungi to host plants. Because plants developing during primary succession are gradually colonized by mycorrhizal fungi, such situations provide good opportunities to study interactions between mycorrhizal colonization and plant 15N content. Here, we present results of a study of nitrogen isotope patterns in ecosystem components during the first 100 years of ecosystem development after glacial retreat, and compare those patterns with those on adjacent mature terrain. Soils in primary succession were depleted in 15N relative to nitrogen-fixing plants. Nonmycorrhizal plants and plants generally colonized by ectomycorrhizal, ericoid, or arbuscular fungi showed similar 15N content very early in succession (-4 to -6‰ ), corresponding to low colonization levels of all plant species. Subsequent colonization of evergreen plants by ectomycorrhizal and ericoid fungi led to a 5-6‰ decline in 15N content, indicating transfer of 15N-depleted N from fungi to plants. The values recorded (-10 to -14‰ ) are among the lowest yet observed in vascular plants. Nonmycorrhizal plants and plants colonized by arbuscular mycorrhizal fungi did not decline in 15N content. Most ectomycorrhizal and saprotrophic fungi were similar in 15N content in early succession (-1 to -3‰ ), with the notable exception of ectomycorrhizal fungi suspected of proteolytic capabilities, which were 15N enriched relative to all other fungi. 15N contents in both plants and soil from the mature site were 5‰ greater than in recently exposed sites. We conclude that 1) the primary nitrogen source to this ecosystem must be atmospheric deposition, 2) low plant 15N content generally corresponds with greater

  14. Changes in mineral {sup 15} N from soils treated with {sup 15} N-urea and {sup 15} N-vinasse incorporated or not to sugar cane straw; Transformacoes do {sup 15} N-mineral em solos tratados com ureia-{sup 15} N e vinhaca-{sup 15} N na presenca ou nao de palha de cana-de-acucar

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Vilma M.; Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear; Trivelin, Paulo C.O. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil); Encarnacao, Fernando A.F. [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil). Dept. de Geologia e Topografia

    1999-11-01

    Changes in N derived from {sup 15} N sources (urea and vinasse), applied to two soils differing in texture (PV sandy, LR clayey), incorporated or not to sugar cane straw (dry leaves and sheathes) and incubated in an open system for 35 days, were evaluated through an isotope technique. Soil samples were collected 7, 14, 21, 28 and 35 days after applications to determine nitrogen fractions (total-N, N H{sub 4}{sup +} - N and NO{sub 3}{sup -} - N) derived from the labelled sources. Mineral N was taken as the sum of N H{sub 4}{sup +} - N and N H{sub 3}{sup -} -N. {sup 15} N-abundances were determined in the concentrated extracts of these fractions. The mineral N net transformation rates were found from the mineral N obtained by taking the difference between the values of two subsequent incubation times. The results showed that mineral N transformation rates were initially positives in the treatments of {sup 15} N-urea, and significantly higher (10,30 mg kg{sup -1} d{sup -1}, PV and 8,08 mg kg{sup -1} d{sup -1}, LR) than those obtained in the treatments with {sup 15} N vinasse (1,11 mg kg{sup -1} dia {sup -1}, PV and 0,55 mg kg{sup -1} dia {sup -1}, LR). In general terms, mineral-N net transformation rates were negative (0,06 and 0,26 mg.kg{sup -1} d{sup -1}, PV; -1,44 and 0,07 mg.kg{sup -1}.d{sup -1}, LR, respective;y for urea and vinasse) indicating prevalence of immobilization. The results also showed small fluctuations among treatments at some of the incubation periods, which reflects the influence of characteristics and properties of both soils. (author) 20 refs., 2 figs., 1 tab.

  15. Enhanced plant growth at reduced N2O emissions: 15N dynamics confirm nitrate capture and release of co-composted biochar

    Science.gov (United States)

    Kammann, Claudia; Schmidt, Hans-Peter; Williams, Anne; Hagemann, Nikolas; Marhan, Sven; Clough, Tim; Mueller, Christoph

    2017-04-01

    Pyrogenic carbon (biochar) produced from biomass may be used as a soil amendment to sequester biomass-C and to mitigate climate change. Moreover, biochar may increase soil fertility and optimize nutrient cycling in agro-ecosystems. However, according to meta-studies large additions (>10 t ha-1) of pure biochar, may only lead to moderate yield increases. Thus, there are no economic benefits for farmers to use biochar. Recently, it has been suggested that biochar may be used as an on-farm nutrient management tool (feed additive, liquid manure treatment, composting) to deliver small doses of nutrients and biochar to the soil each year. It may also be used as a carrier for (organic) nutrients in small doses (0.5 - 2 t ha-1) in the root zone; recent studies reported considerably increased yields. The mechanisms, however, are not well understood. Co-composted biochar was recently shown to promote plant growth due to its nutrient delivery and release capabilities, particularly nitrate (NO3-). To gain further insights into biochar-nitrogen (N) interactions, we conducted a 15N labelling-tracing study under controlled conditions with treatments consisting of a non-biochar amended control, 2% (wt/wt) of untreated biochar particles (BCpure ,no intrinsic content of nitrate) and a 2% co-composted biochar (BCcomp, 5.3 g NO3-N kg-1 as a result of composting), replicated thrice. Biochars were added to a sandy loam soil in jars (200 g) planted with barley (Hordeum vulgare L.) seedlings. Fertilizer (NH4NO3) was homogenously added with either the ammonium (NH4+) or the nitrate (NO3-) pools 15N labelled (60 atom% 15N) hours before planting the seedlings. Sets of 18 jars were harvested on days 1, 3, 8, 15 and 29 and nitrogen pools were analysed to trace 15N fertilizer fate (soil mineral N, plant biomass, biochar particles, nitrous oxide (N2O) emissions). Interestingly, both BCpure and BCcomp captured fertilizer 15N from the soil matrix within hours of addition, with higher capture of 15

  16. Regional assessment of N saturation using foliar and root δ15N

    Science.gov (United States)

    L.H. Pardo; P.H. Templer; C.L. Goodale; S. Duke; P.M. Groffman; M.B. Adams; P. Boeckx; J. Boggs; J. Campbell; B. Colman; J. Compton; B. Emmett; P. Gundersen; J. Kjonaas; G. Lovett; M. Mack; A. Magill; M. Mbila; M.J. Mitchell; G. McGee; S. McNulty; K. Nadelhoffer; S. Ollinger; D. Ross; H. Rueth; L. Rustad; P. Schaberg; S. Schiff; P. Schleppi; J. Spoelstra; W. Wessel

    2006-01-01

    N saturation induced by atmospheric N deposition can have serious consequences for forest health in many regions. In order to evaluate whether foliar δ15N may be a robust, regional-scale measure of the onset of N saturation in forest ecosystems, we assembled a large dataset on atmospheric N deposition, foliar and root δ

  17. Quantifying the production of dissolved organic nitrogen in headwater streams using 15N tracer additions

    Science.gov (United States)

    Laura T. Johnson; Jennifer L. Tank; Robert O. Hall; Patrick J. Mullholland; Stephen K. Hamilton; H. Maurice Valett; Jackson R. Webster; Melody J. Bernot; William H. McDowell; Bruce J. Peterson; Suzanne M. Thomas

    2013-01-01

    Most nitrogen (N) assimilation in lake and marine ecosystems is often subsequently released via autochthonous dissolved organic nitrogen (DON) production, but autochthonous DON production has yet to be quantified in flowing waters. We measured in-stream DON production following 24 h 15N-nitrate (NO3-...

  18. Effect of dietary 15N-CCC on 15N content of meat and eggs of ...

    African Journals Online (AJOL)

    Udo ter Meulen

    2Department of Animal Nutrition and Feed Science, Jambi University, Kampus Pinang Masak Mendalo Darat, Jambi ... and egg albumen were dependent on dietary 15N-CCC concentrations and differed significantly between tissues for ..... Biochemical behaviour in 2-chloroethyl trimethylammonium chloride in wheat and in.

  19. The Role of Anthropogenic Activity and Climate on δ15N Values of Cave Bat Guano

    Science.gov (United States)

    Cleary, D. M.; Onac, B. P.; Forray, F. L.; Wynn, J. G.

    2016-12-01

    Interest in the use of bat guano, a paleoclimate and paleoenvironmental resource, has rapidly increased over the past decade. However, to this point the utility of the δ15N values of guano as a potential proxy remains poorly understood. In contrast to the preservation of the original carbon isotopic composition of guano, δ15N values have the potential to be altered as a result of processes of nitrogen (N) cycling such as denitrification. However, the probability of N loss is relatively diminished in younger guano. Here we present a 1.5 m guano core from Zidită Cave in western Romania that began accumulating at ca. 913 ± 30 yr BP. To determine the utility of N isotopes in guano studies, the δ15N time-series was compared to δ13C time series and pollen records of the same core to determine if the environmental impact (pollen) or water availability (δ13C values) has an effect on N cycling. Unlike to previous guano studies, the N content in the core is nearly constant (%N > 9 %) for over 1 m of the core, indicating limited diagenesis. Although major changes in anthropogenic activities may have influenced some δ15N variation, some inconsistencies suggest this is not the primary controller. However, the correlation between δ15N and δ13C values (p < 0.01) in this C3-plant dominated ecosystem has been interpreted to reflect variation driven largely by water availability. Wetter periods indicated by lower δ13C values correspond with higher δ15N values of guano. These results indicate that when the area surrounding the Zidită Cave receives an increase in rainfall the N-cycle becomes more open with a decreased rate of denitrification or other processes that accumulate 15N in the soil reservoir. A 10-year instrumental precipitation dataset agrees with the relationship found between δ13C and δ15N time series. These results suggest that guano δ15N values from Zidită Cave are a suitable proxy record of climate for this type of system, but we emphasize that this

  20. Species differences in nitrogen cycling in a humid sub-tropical forest inferred from 15N natural abundance

    Science.gov (United States)

    Abdisa Gurmesa, Geshere; Lu, Xiankai; Gundersen, Per; Mao, Qinggong; Zhou, Kaijun; Mo, Jiangming

    2017-04-01

    Studies of natural abundance of stable nitrogen isotope (δ15N) of ecosystems can provide integrated information about N status and N cycling rates within the ecosystems. Plant species with different N cycling traits can affect ecosystem δ15N, but such differences are poorly explored in tropical forests. This study evaluates the extent of variation in plant δ15N among co-occurring sub-tropical tropical tree species in old-growth mixed broadleaved forest in southern China. We compared leaf δ15N values among five co-occurring tree species under ambient deposition (control plots), and variation in plant δ15N response to a decade of N addition (N-plots) and to a one-year enriched 15N addition to both treatments in the study forest. We found significant differences in leaf δ15N values among tree species (up to 3‰) both in control and N-plots. Responses of leaf δ15N to N and 15N addition also differ among the tree species. These differences are explained by differences in N acquisition strategies (dependence on soil N and/or deposition N among the plant species) that is partly related to differences in mycorrhizal association among the studied plants. Our results indicate that plant species in N-rich tropical forests could have distinct N cycling traits as observed in many predominantly N-limited temperate and boreal forests. The finding, therefore, highlights the importance of considering tree species variation in studying N cycling in N-rich tropical forests.

  1. Effect of the supply dose on the {sup 15}N enrichment level of cow`s milk nitrogenous fractions; Influence de la dose d`apport sur le niveau d`enrichissement en {sup 15}N des fractions azotees du lait de vache

    Energy Technology Data Exchange (ETDEWEB)

    Colin, O.; Laurent, F.; Vignon, B. [INRA, 54 - Vandoeuvre-les-Nancy (France); Antoine, J.M. [Boussois-Souchon-Neuvesel (BSN), 75 - Paris (France)

    1994-12-31

    Production of cow milk {sup 15}N-labelled proteins is necessary for the study of their digestion by man. An adequate enrichment is required for compatibility with utilization constraints (application dose, studied fractions...). A test was conducted with five cows in order to optimize the utilization of labelled ammonium sulphate in the cow diet for {sup 15}N enrichment of the milk nitrogenous matter. Doses and supply timing of labelled compounds are discussed. 3 figs., 3 refs.

  2. Biosynthetic preparation of L-(/sup 13/C)- and (/sup 15/N)glutamate by Brevibacterium flavum

    Energy Technology Data Exchange (ETDEWEB)

    Walker, T.E.; London, R.E.

    1987-01-01

    The biosynthesis of isotopically labeled L-glutamic acid by the microorganism Brevibacterium flavum was studied with a variety of carbon-13-enriched precursors. The purpose of this study was twofold: (i) to develop techniques for the efficient preparation of labeled L-glutamate with a variety of useful labeling patterns which can be used for other metabolic studies, and (ii) to better understand the metabolic events leading to label scrambling in these strains. B. flavum, which is used commercially for the production of monosodium glutamate, has the capability of utilizing glucose or acetate as a sole carbon source, and important criterion from the standpoint of developing labeling strategies. Unfortunately, singly labeled glucose precursors lead to excessive isotopic dilution which reduces their usefulness. Studies with (3-/sup 13/C)pyruvate indicate that this problem can in principle be overcome by using labeled three-carbon precursors; however, conditions could not be found which would lead to an acceptable yield of isotopically labeled L-glutamate. In contrast, (1-/sup 13/C)- or (2-/sup 13/C)acetate provides relatively inexpensive, readily available precursors for the production of selectively labeled, high enriched L-glutamate. The preparation of L-(/sup 15/N)glutamate from (/sup 15/N)ammonium sulfate was carried out and is a very effective labeling strategy. Analysis of the isotopic distribution in labeled glutamate provides details about the metabolic pathways in these interesting organisms.

  3. Patterns in δ15N in roots, stems, and leaves of sugar maple and American beech seedlings, saplings, and mature trees

    Science.gov (United States)

    L.H. Pardo; P. Semaoune; P.G. Schaberg; C. Eagar; M. Sebilo

    2013-01-01

    Stable isotopes of nitrogen (N) in plants are increasingly used to evaluate ecosystem N cycling patterns. A basic assumption in this research is that plant δ15N reflects the δ15N of the N source. Recent evidence suggests that plants may fractionate on uptake, transport, or transformation of N. If the...

  4. Multiyear fate of a 15 N tracer in a mixed deciduous forest: retention, redistribution, and differences by mycorrhizal association.

    Science.gov (United States)

    Goodale, Christine L

    2017-02-01

    The impact of atmospheric nitrogen deposition on forest ecosystems depends in large part on its fate. Past tracer studies show that litter and soils dominate the short-term fate of added 15 N, yet few have examined its longer term dynamics or differences among forest types. This study examined the fate of a 15 N-NO3- tracer over 5-6 years in a mixed deciduous stand that was evenly composed of trees with ectomycorrhizal and arbuscular mycorrhizal associations. The tracer was expected to slowly mineralize from its main initial fate in litter and surface soil, with some 15 N moving to trees, some to deeper soil, and some net losses. Recovery of added 15 N in trees and litterfall totaled 11.3% both 1 and 5-6 years after the tracer addition, as 15 N redistributed from fine and especially coarse roots into cumulative litterfall and small accumulations in woody tissues. Estimates of potential carbon sequestration from tree 15 N recovery amounted to 12-14 kg C per kg of N deposition. Tree 15 N acquisition occurred within the first year after the tracer addition, with no subsequent additional net transfer of 15 N from detrital to plant pools. In both years, ectomycorrhizal trees gained 50% more of the tracer than did trees with arbuscular mycorrhizae. Much of the 15 N recovered in wood occurred in tree rings formed prior to the 15 N addition, demonstrating the mobility of N in wood. Tracer recovery rapidly decreased over time in surface litter material and accumulated in both shallow and deep soil, perhaps through mixing by earthworms. Overall, results showed redistribution of tracer 15 N through trees and surface soils without any losses, as whole-ecosystem recovery remained constant between 1 and 5-6 years at 70% of the 15 N addition. These results demonstrate the persistent ecosystem retention of N deposition even as it redistributes, without additional plant uptake over this timescale. © 2016 John Wiley & Sons Ltd.

  5. Synthesis and Characterization of Thymine-15N2

    Directory of Open Access Journals (Sweden)

    XU Jian-fei

    2016-02-01

    Full Text Available A novel and mild synthesis method of thymine-15N2 was designed. Ethyl formate and ethyl propionate as raw materials, the intermediate ethyl 2-formylpropionate was condensed under sodium metal, the target compound thymine-15N2 was obtained by condensation with isotope urea-15N2 under acid catalysis. Synthesis route had the advantages of simple operation, short process flow and less side product. The yield was more than 80% and isotope 15N abundance did not diluted. The product was characterized by HPLC, IR, MS, 1H NMR and 13C NMR. The chemical purity was more than 99% and 15N enrichment was more than 98 atom%.

  6. Belowground fate of (15)N injected into sweetgum trees (Liquidambar styraciflua) at the ORNL FACE Experiment.

    Science.gov (United States)

    Garten, Charles T; Brice, Deanne J

    2009-10-01

    Nitrogen (N) cycling can be an important constraint on forest ecosystem response to elevated atmospheric CO(2). Our objective was to trace the movement of (15)N, injected into tree sap, to labile and stable forms of soil organic matter derived partly from the turnover of tree roots under elevated (545 ppm) and ambient (394 ppm) atmospheric CO(2) concentrations at the Oak Ridge National Laboratory (ORNL) FACE (Free-Air Carbon Dioxide Enrichment) Experiment. Twenty-four sweetgum trees, divided equally between CO(2) treatments, were injected with 3.2 g (15)N-ammonium sulfate (99 atom %), and soil samples were collected beneath the trees over a period of 89 weeks. For 16 cm deep soil samples collected beneath the study trees, there was 28% more fine root (less than or equal to 2 mm diameter) biomass under elevated CO(2) (P = 0.001), but no significant treatment effect on the amounts of necromass, coarse root biomass, or on the N concentrations in tree roots and necromass. Nitrogen-15 moved quickly into roots from the stem injection site and the (15)N content of roots, necromass, and labile organic matter (i.e. particulate organic matter, POM) increased over time. At 89 weeks post-injection, approximately 76% of the necromass (15)N originated from fine root turnover. Nitrogen-15 in POM had a relatively long turnover time (47 weeks) compared with (15)N in roots (16 to 22 weeks). Over the 1.7 year period of the study, (15)N moved from roots into slower cycling POM and the disparity in turnover times between root N and N in POM could impose progressive limitations on soil N availability with stand maturation irrespective of atmospheric CO(2), especially if the release of N through the decomposition of POM is essential to sustain forest net primary production. Published in 2009 by John Wiley & Sons, Ltd.

  7. Leaf δ15N as a temporal integrator of nitrogen-cycling processes at the Mojave Desert FACE experiment

    Science.gov (United States)

    Sonderegger, D.; Koyama, A.; Jin, V.; Billings, S. A.; Ogle, K.; Evans, R. D.

    2011-12-01

    Ecosystem response to elevated carbon dioxide (CO2) in arid environments is regulated primarily by water, which may interact with nitrogen availability. Leaf nitrogen isotope composition (δ15N) can serve as an important indicator of changes in nitrogen dynamics by integrating changes in plant physiology and ecosystem biogeochemical processes. Because of this temporal integration, careful modeling of the antecedent conditions is necessary for understanding the processes driving variation in leaf δ15N. We measured leaf δ15N of Larrea tridentata (creosotebush) over the 10-year lifetime of the Nevada Desert Free-Air CO2 Enrichment (FACE) experiment. Leaf δ15N exhibited two patterns. First, elevated atmospheric CO2 significantly increased Larrea leaf δ15N by approximately 2 to 3 % compared to plants exposed to ambient CO2 concentrations Second, plants in both CO2 treatments exhibited significant seasonal cycles in leaf δ15N, with higher values during the fall and winter seasons. We modeled leaf δ15N using a hierarchical Bayesian framework that incorporated soil moisture, temperature, and the Palmer Drought Severity Index (PDSI) covariates in addition to a CO2 treatment effect and plot random effects. Antecedent moisture effects were modeled by using a combination of the previous season's aggregated conditions and a smoothly varying weighted average of the months or weeks directly preceding the observation. The time lag between the driving antecedent condition and the observed change in leaf δ15N indicates a significant and unobserved process mechanism. Preliminary results suggest a CO2 treatment interaction with the lag effect, indicating a treatment effect on the latent process.

  8. δ15N value does not reflect fasting in mysticetes.

    Directory of Open Access Journals (Sweden)

    Alex Aguilar

    Full Text Available The finding that tissue δ(15N values increase with protein catabolism has led researchers to apply this value to gauge nutritive condition in vertebrates. However, its application to marine mammals has in most occasions failed. We investigated the relationship between δ(15N values and the fattening/fasting cycle in a model species, the fin whale, a migratory capital breeder that experiences severe seasonal variation in body condition. We analyzed two tissues providing complementary insights: one with isotopic turnover (muscle and one that keeps a permanent record of variations in isotopic values (baleen plates. In both tissues δ(15N values increased with intensive feeding but decreased with fasting, thus contradicting the pattern previously anticipated. The apparent inconsistency during fasting is explained by the fact that a individuals migrate between different isotopic isoscapes, b starvation may not trigger significant negative nitrogen balance, and c excretion drops and elimination of 15N-depleted urine is minimized. Conversely, when intensive feeding is resumed in the northern grounds, protein anabolism and excretion start again, triggering 15N enrichment. It can be concluded that in whales and other mammals that accrue massive depots of lipids as energetic reserves and which have limited access to drinking water, the δ15N value is not affected by fasting and therefore cannot be used as an indication of nutritive condition.

  9. {sup 15}N uptake from manure and fertilizer sources by three consecutive crops under controlled conditions

    Energy Technology Data Exchange (ETDEWEB)

    Quiroga Garza, Hector Mario, E-mail: quiroga.mario@inifap.gob.m [Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias (INIFAP), Coahuila (Mexico); Delgado, Jorge A.; Wong, Jose Antonio Cueto, E-mail: jorge.delgado@ars.usda.go, E-mail: cueto.jose@inifap.gob.m [United States Dept. of Agriculture (USDA), Fort Collins, CO (United States). Agricultural Research Service. Soil Plant Nutrient Research Unit; Lindemann, William C., E-mail: wlindema@nmsu.ed [New Mexico State University (NMST), Las Cruces, NM (United States). Dept. Agronomy and Horticulture

    2009-09-15

    There are several regions of the world where soil N analysis and/or N budgets are not used to determine how much N to apply, resulting in higher than needed N inputs, especially when manure is used. One such region is the North Central 'La Comarca Lagunera', one of the most important dairy production areas of Mexico. We conducted a unique controlled greenhouse study using {sup 15}N fertilizer and {sup 15}N isotopic-labeled manure that was labeled under local conditions to monitor N cycling and recovery under higher N inputs. The manure-N treatment was applied only once and was incorporated in the soil before planting the first forage crop at an equivalent rate of 30, 60 and 120 Mg ha{sup -1} dry manure. The {sup 15}N treatments were equivalent to 120 and 240 kg ha{sup -1} (NH{sub 4}){sub 2}SO{sub 4}-N for each crop. The total N fertilizer for each N fertilized treatment were 360, and 720 kg ha{sup -1} N. We found very low N recoveries: about 9 % from the manure N inputs, lower than the 22 to 25 % from the fertilizer N inputs. The manure N recovered below ground in soil and roots ranged from 82 to 88 %. The low recoveries of N by the aboveground and low soil inorganic nitrate (NO{sup 3}-N) and ammonium (NH{sub 4}-N) content after the third harvested suggested that most of the {sup 15}N recovered below ground was in the soil organic form. The losses from manure N inputs ranged from 3 to 11 %, lower than the 34 to 39 % lost from fertilizer N sources. Our study shows that excessive applications of manure or fertilizer N that are traditionally used in this region will not increase the rate of N uptake by aboveground compartment but will increase the potential for N losses to the environment. (author)

  10. δ15N in the turtle grass from the Mexican Caribbean

    Science.gov (United States)

    Talavera-Saenz, A.; Sanchez, A.; Ortiz-Hernandez, M.

    2013-05-01

    Nutrient inputs associated with population growth threaten the integrity of coastal ecosystems. To assess the rapid increase in tourism, we compared the δ15N from Thalassia testudinum collected at sites with different levels of tourism development and population to detect the N inputs of wastewater discharge (WD) along the coast of Quintana Roo. The contributions of nitrogen enriched in 15N are directly related to the increase of WD inputs in areas of high tourism development (Nichupte Lagoon in Cancun, >3 million tourists per year from 2007 to 2011 and 0.7 million of resident population) and decreased towards Bahia Akumal and Tulum (>3 million tourists per year from 2007 to 2011 and 0.15 million of resident population). The δ15N from T. testudinum was significantly lower at Mahahual and Puerto Morelos (about 0.4 million tourists per year in 2007 to 2011 and 0.25 million of resident population) than other the sites. In areas of the lowest development and with tourist activity restricted and small population, such as the Yum Balam Reserve and Sian Ka'an Biosphere Reserve, the δ15N values were in much higher enrichment that Mahahual and Puerto Morelos. Therefore is suggested that Mahahual and Puerto Morelos may be used for baseline isotopic monitoring, over environmental pressure on the reef lagoon ecosystem, where tourist activities and population are growing very slow rate. The anthropogenic N input has the potential to impact, both environmentally and economically, the seagrass meadows and the coral reefs along the coast of Quintana Roo and the Caribbean.

  11. Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem

    DEFF Research Database (Denmark)

    Andresen, Louise Christoffersen; Jonasson, Sven; Strom, Lena

    2008-01-01

    15N labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of 15N label in mycorrhizal and non-mycorrhiza......, the differences in 15N uptake patterns may also be due to differences in leaf longevity and woodiness between plant functional groups.......-mycorrhizal plants and in soil microorganisms, in order to reveal probable differences in acquisition patterns between the two functional plant types and between plants and soil microorganisms. Three weeks after the label addition, with the 15N-forms added with same amount of nitrogen per square meter, we analyzed...... the 15N-enrichment in total soil, in soil K2SO4 (0.5 M) extracts and in the microbial biomass after vacuum-incubation of soil in chloroform and subsequent K2SO4 extraction. Furthermore the 15N-enrichment was analyzed in current years leaves of the dominant plant species sampled three, five and 21 days...

  12. {sup 15}N metabolic test for the determination of phytotoxic effects of chemicals and contaminated environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Jung, K.; Segner, H.; Schueuermann, G. [UFZ - Umweltforschungszentrum Leipzig-Halle GmbH, Leipzig (Germany). Sektion Chemische Oekotoxikologie; Kaletta, K. [Halle-Wittenberg Univ., Halle (Germany). Inst. fuer Biochemie

    1999-07-01

    A stable isotope {sup 15}N-nitrogen test (ESIMA=Ecotoxicological Stable Isotope Metabolic Assay) was developed to assess biological effects and the potential toxicological hazard of chemicals and contaminated environmental samples on plant metabolism. The assay measures the effect of toxicants on the incorporation of a {sup 15}N labelled tracer into the total nitrogen fraction (both the nonprotein and protein fraction) of plants. Segments of Pisum arvense epicotyls are used as test substrates because of their high metabolic activity. The plant material is incubated under standardised conditions for two hours; subsequently {sup 15}N incorporation is analysed by determining the {sup 15}N abundance ({sup 15}N atom-%) in the epicotyl segments. The effects of toxicants are evaluated by comparing the {sup 15}N incorporation rates of control tissue and epicotyl segments exposed to individual chemicals or complex environmental samples. The specificity and sensitivity of effects as indicated by ESIMA were compared with effect as measured by two establish ecotoxicological bioassays, the pollen tube growth test using pollen of Nicotiana sylvestris and the bacterial luminescence inhibition test using pollen of Photobacterium phosphoreum. The results of the study clearly indicate the suitability of ESIMA for assessing toxic impacts on plant nitrogen metabolism. (orig.)

  13. Range expansion of the jumbo squid in the NE Pacific: δ15N decrypts multiple origins, migration and habitat use.

    Science.gov (United States)

    Ruiz-Cooley, Rocio I; Ballance, Lisa T; McCarthy, Matthew D

    2013-01-01

    Coincident with climate shifts and anthropogenic perturbations, the highly voracious jumbo squid Dosidicus gigas reached unprecedented northern latitudes along the NE Pacific margin post 1997-98. The physical or biological drivers of this expansion, as well as its ecological consequences remain unknown. Here, novel analysis from both bulk tissues and individual amino acids (Phenylalanine; Phe and Glutamic acid; Glu) in both gladii and muscle of D. gigas captured in the Northern California Current System (NCCS) documents for the first time multiple geographic origins and migration. Phe δ(15)N values, a proxy for habitat baseline δ(15)N values, confirm at least three different geographic origins that were initially detected by highly variable bulk δ(15)N values in gladii for squid at small sizes (squid (>60 cm) converged, indicating feeding in a common ecosystem. The strong latitudinal gradient in Phe δ(15)N values from composite muscle samples further confirmed residency at a point in time for large squid in the NCCS. These results contrast with previous ideas, and indicate that small squid are highly migratory, move into the NCCS from two or more distinct geographic origins, and use this ecosystem mainly for feeding. These results represent the first direct information on the origins, immigration and habitat use of this key "invasive" predator in the NCCS, with wide implications for understanding both the mechanisms of periodic D. gigas population range expansions, and effects on ecosystem trophic structure.

  14. 15N fractionation in infrared-dark cloud cores

    Science.gov (United States)

    Zeng, S.; Jiménez-Serra, I.; Cosentino, G.; Viti, S.; Barnes, A. T.; Henshaw, J. D.; Caselli, P.; Fontani, F.; Hily-Blant, P.

    2017-07-01

    Context. Nitrogen is one of the most abundant elements in the Universe and its 14N/15N isotopic ratio has the potential to provide information about the initial environment in which our Sun formed. Recent findings suggest that the solar system may have formed in a massive cluster since the presence of short-lived radioisotopes in meteorites can only be explained by the influence of a supernova. Aims: We seek to determine the 14N/15N ratio towards a sample of cold and dense cores at the initial stages in their evolution. Methods: We observed the J = 1 → 0 transitions of HCN, H13CN, HC15N, HN13C, and H15NC towards a sample of 22 cores in four infrared-dark clouds (IRDCs) which are believed to be the precursors of high-mass stars and star clusters. Assuming LTE and a temperature of 15 K, the column densities of HCN, H13CN, HC15N, HN13C, and H15NC are calculated and their 14N/15N ratio is determined for each core. Results: The 14N/15N ratios measured in our sample of IRDC cores range between 70 and ≥763 in HCN and between 161 and 541 in HNC. These ratios are consistent with the terrestrial atmosphere (TA) and protosolar nebula (PSN) values, and with the ratios measured in low-mass prestellar cores. However, the 14N/15N ratios measured in cores C1, C3, F1, F2, and G2 do not agree with the results from similar studies towards the same cores using nitrogen bearing molecules with nitrile functional group (-CN) and nitrogen hydrides (-NH) although the ratio spread covers a similar range. Conclusions: Relatively low 14N/15N ratios amongst the four-IRDCs were measured in IRDC G which are comparable to those measured in small cosmomaterials and protoplanetary disks. The low average gas density of this cloud suggests that the gas density, rather than the gas temperature, may be the dominant parameter influencing the initial nitrogen isotopic composition in young PSN. The reduced spectra (FITS files) are only available at the CDS via anonymous ftp to http

  15. Incorporation of (15)N from spiked cattle dung pats into soil under two moorland plant communities.

    Science.gov (United States)

    Shepherd, M J; Anderson, J M; Bol, R; Allen, D K

    2000-01-01

    The rate and depth of cattle dung incorporation into moorland soil may be an important factor influencing plant community dynamics through its effects on soil nutrient availability. This study traces the incorporation of (15)N-labelled dung into a moorland soil under two vegetation types in Dartmoor National Park, UK. Cores of treated and control soil 10 cm deep were collected at 2, 4, 8 and 16 week intervals and divided into 2 cm depth increments. Soil samples were freeze-dried, ground and analysed for atom% (15)N and %N content using continuous-flow isotope-ratio mass spectrometry. The contribution of dung N to the soil N pool was estimated by changes in atom% (15)N of the soil. The incorporation of dung dry matter into the soil was also calculated. The labile component of the dung N was incorporated deeper and more rapidly into soil under grass than under heather vegetation. The implications of these processes for the dynamics of upland plant communities are considered in relation to the ability of plants to compete for nutrients. Copyright 2000 John Wiley & Sons, Ltd.

  16. Impacts of water and nitrogen addition on nitrogen recovery in Haloxylon ammodendron dominated desert ecosystems.

    Science.gov (United States)

    Cui, Xiaoqing; Yue, Ping; Gong, Yanming; Li, Kaihui; Tan, Dunyan; Goulding, Keith; Liu, Xuejun

    2017-12-01

    Desert ecosystems are likely to change in response to global climate change and nitrogen (N) deposition. The effects of increased precipitation and N deposition on plant growth and the N cycle largely depend on N allocation and N recovery efficiency in the plant-soil ecosystem, but there is limited research on this in desert ecosystems. Here we report results using double-labeled (15)NH4(15)NO3 (30 and 60kgNha(-1)yr(-1)) as a tracer under ambient (no additional water addition) and enhanced precipitation (60mm water addition) in a Haloxylon ammodendron dominated ecosystem in the Gurbantunggut Desert of Northwest China. Herbaceous plants were a significantly larger sink for added (15)N than the H. ammodendron trees, and N retention varied with water and N addition, relative to growing season precipitation. The retention of added (15)N varied within the components of H. ammodendron, with the stems retaining most, followed by the assimilation branches. Soil was the dominant sink for added (15)N, in which the topsoil and subsoil respond differently to water and N addition over the two-year period. Nitrogen relative recovery percentage in the whole ecosystem ranged from 43% to 61%, lower than average recovery rate in temperate forests; N tracer recovery percentage significantly increased with water addition but decreased with enhanced N deposition. Future N cycling in central Asian deserts will depend on changes in precipitation. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. A novel method for trapping and analyzing 15N in NO for tracing NO sources

    Science.gov (United States)

    Kang, Ronghua; Mulder, Jan; Dörsch, Peter

    2016-04-01

    15N isotope tracing is an effective and direct approach to investigate the biological and chemical sources of nitric oxide (NO) in soil. However, NO is highly reactive and rapidly converted to nitrogen dioxide (NO2) in the presence of ozone. Various chemical conversions of NO to the more stable solutes nitrite (NO2-) and nitrate (NO3-) have been proposed, which allow analysing the 15N abundance without major fractionation. However, NO emissions from soils are usually small, posing major challenges to conversion efficiency and background contamination. Here we present a novel method in which NO is oxidized to NO2- by chromium trioxide (CrO3) prior to conversion to NO2- and NO3- in an alkaline hydrogen peroxide (H2O2) solution. Immediately following trapping, manganese dioxide (MnO2) and 5M HCl are added to remove excess H2O2, and to adjust the pH to around 6.0-7.0, respectively. The resulting solution can be stored until analysis and is none-toxic, allowing to use a modified denitrifier method (Zhu et al., submitted), where NO2- and NO3- are reduced quantitatively to nitrous oxide (N2O). Optimum NO conversion rates of > 90% even at extremely low initial NO concentration were obtained with 4% H2O2, 0.5 M NaOH, and 0.5 L min-1 gas flow rate. In a laboratory test, using NO gas with different 15N signals produced from unlabelled and labelled NO2-, we found an overall precision of 0.4‰ for unlabelled and 49.7‰ for NO enriched with 1.0 atom% 15N, respectively. This indicates that this method can be used for both natural abundance studies of NO, as well as in labelling studies tracing NO sources. Zhu J, Yu L, Bakken LR, Mørkved PT, Mulder J, Dörsch P. Controlled induction of denitrification in Pseudomonas aureofaciens: a modified denitrifier method for 15N and 18O analysis in NO3- from natural water samples by IRMS. Submitted.

  18. Comparison of three 15N methods to correct for microbial contamination when assessing in situ protein degradability of fresh forages.

    Science.gov (United States)

    Kamoun, M; Ammar, H; Théwis, A; Beckers, Y; France, J; López, S

    2014-11-01

    The use of stable (15)N as a marker to determine microbial contamination in nylon bag incubation residues to estimate protein degradability was investigated. Three methods using (15)N were compared: (15)N-labeled forage (dilution method, LF), (15)N enrichment of rumen solids-associated bacteria (SAB), and (15)N enrichment of rumen liquid-associated bacteria (LAB). Herbage from forages differing in protein and fiber contents (early-cut Italian ryegrass, late-cut Italian ryegrass, and red clover) were freeze-dried and ground and then incubated in situ in the rumen of 3 steers for 3, 6, 12, 24, and 48 h using the nylon bag technique. The (15)N-labeled forages were obtained by fertilizing the plots where herbage was grown with (15)NH4 (15)NO3. Unlabeled forages (obtained from plots fertilized with NH4NO3) were incubated at the same time that ((15)NH4)2SO4 was continuously infused into the rumen of the steers, and then pellets of labeled SAB and LAB were isolated by differential centrifugation of samples of ruminal contents. The proportion of bacterial N in the incubation residues increased from 0.09 and 0.45 g bacterial N/g total N at 3 h of incubation to 0.37 and 0.85 g bacterial N/g total N at 48 h of incubation for early-cut and late-cut ryegrass, respectively. There were differences (P forage (late-cut ryegrass) was 0.51, whereas the corrected values were 0.85, 0.84, and 0.77 for the LF, SAB, and LAB methods, respectively. With early-cut ryegrass and red clover, the differences between uncorrected and corrected values ranged between 6% and 13%, with small differences among the labeling methods. Generally, methods using labeled forage or labeled SAB and LAB provided similar corrected degradability values. The accuracy in estimating the extent of degradation of protein in the rumen from in situ disappearance curves is improved when values are corrected for microbial contamination of the bag residue.

  19. Synthesis and {sup 15}N NMR spectra of 1- and 4-{sup 15}N-2,3,5-trimethylpyrazines and their N-oxides

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Mikiko; Sakuma, Chiseko; Kawachi, Shinji; Tabei, Katsumi; Ohta, Akihiro [Tokyo Coll. of Pharmacy (Japan); Kerim, Ablikim; Kurihara, Teruo [Josai Univ., Sakado, Saitama (Japan). Faculty of Science

    1995-01-01

    4-{sup 15}N-2,3,5-Trimethylpyrazine was synthesized by dechlorination of 4-{sup 15}N-6-chloro-2,3,5-trimethylpyrazine, the key intermediate, derived from {sup 15}N-DL-alanine. 1-{sup 15}N-2,3,5-Trimethylpyrazine was prepared by decarboxylation of 1-{sup 15}N-2,3,5-trimethyl-pyrazine-6-carboxylic acid obtained by the Pummerer type rearrangement of 1-{sup 15}N-tetramethylpyrazine 1-oxide (7) followed by oxidation. 1- and 4-oxides and 1,4-dioxides of the above {sup 15}N-trimethylpyrazines were also obtained by treatment with sodium perborate in acetic acid. (Author).

  20. Appraisal of {sup 15}N enrichment and {sup 15}N natural abundance methods for estimating N{sub 2} fixation by understorey Acacia leiocalyx and A. disparimma in a native forest of subtropical Australia

    Energy Technology Data Exchange (ETDEWEB)

    Bai, Shahla Hosseini; Xu, Zhihong; Blumfield, Timothy J. [Griffith Univ., Nathan, Brisbane, QLD (Australia). School of Biomolecular and Physical Sciences, Environmental Futures Centre; Sun, Fangfang [Guangdong Academy of Agricultural Sciences, Guangzhou (China). Research Centre for Quality, Safety and Standard of Agricultural Products; Chen, Chengrong [Griffith Univ., Nathan, Brisbane, QLD (Australia). School of Environment, Environmental Futures Centre; Wild, Clyde [Griffith Univ., Gold Coast, QLD (Australia). School of Environment, Environmental Futures Centre

    2012-05-15

    Purpose: It is anticipated that global climate change will increase the frequency of wildfires in native forests of eastern Australia. Understorey legumes such as Acacia species play an important role in maintaining ecosystem nitrogen (N) balance through biological N fixation (BNF). This is particularly important in Australian native forests with soils of low nutrient status and frequent disturbance of the nutrient cycles by fires. This study aimed to examine {sup 15}N enrichment and {sup 15}N natural abundance techniques in terms of their utilisation for evaluation of N{sub 2} fixation of understorey acacias and determine the relationship between species ecophysiological traits and N{sub 2} fixation. Materials and methods: A trial was established at sites 1 and 2 located at Toohey Forest, Queensland, Australia, a eucalypt-dominated native forest, to examine the determination of BNF using {sup 15}N enrichment and {sup 15}N natural abundance methods. Toohey Forest is an urban forest and subjected to frequent fuel reduction burns to protect the adjacent properties. Plant physiological status was measured to determine the relationship between physiological and N{sub 2} fixation activities. Results and discussion: Both {sup 15}N enrichment and {sup 15}N natural abundance techniques may be used to estimate N{sub 2} fixation of acacia tree species. The estimation of BNF using {sup 15}N enrichment was higher than those of the {sup 15}N natural abundance method. A grass reference plant, Themeda triandra, as well as tree reference plants provided an appropriate {delta}{sup 15}N signal. Potential B values for Acacia spp. between -0.3 permille and 1.0 permille provided an acceptable BNF estimation. This suburban forest is located nearby a busy highway leading to N deposition over time with consequent negative {delta}{sup 15}N signal. This N deposition may explain the separation between the {delta}{sup 15}N signal of the acacias and that of the reference plants which led to

  1. Bradyrhizobium strain and the {sup 15}N natural abundance quantification of biological N{sub 2} fixation in soybean

    Energy Technology Data Exchange (ETDEWEB)

    Guimaraes, Ana Paula [Universidade Estadual do Norte Fluminense (UENF), Campos dos Goytacases, RJ (Brazil). Centro de Ciencias e Tecnologias Agropecuarias (CCTA). Dept. de Producao Vegetal; Morais, Rafael Fiusa de; Urquiaga, Segundo; Boddey, Robert Michael; Alves, Bruno Jose Rodrigues [EMBRAPA Agrobiologia, Seropedica, RJ (Brazil)]. E-mail: bruno@cnpab.embrapa.br

    2008-09-15

    In commercial plantations of soybean in both the Southern and the Cerrado regions, contributions from biological nitrogen fixation (BNF) are generally proportionately high. When using the {sup 15}N natural abundance technique to quantify BNF inputs, it is essential to determine, with accuracy, the {sup 15}N abundance of the N derived from BNF (the 'B' value). This study aimed to determine the effect of four recommended strains of Bradyrhizobium spp. (two B. japonicum and two B. elkanii) on the 'B' value of soybean grown in pots in an open field using an equation based on the determination of {delta}{sup 15}N natural abundance in a non-labelled soil, and estimate of the contribution of BNF derived from the use of {sup 15}N-isotope dilution in soils enriched with {sup 15}N. To evaluate N{sub 2} fixation by soybean, three non-N{sub 2}-fixing reference crops were grown under the same conditions. Regardless of Bradyrhizobium strain, no differences were observed in dry matter, nodule weight and total N between labelled and non-labelled soil. The N{sub 2} fixation of the soybeans grown in the two soil conditions were similar. The mean 'B' values of the soybeans inoculated with the B. japonicum strains were -1.84 per mille and -0.50 per mille, while those inoculated with B. elkanii were -3.67 per mille and -1.0 per mille, for the shoot tissue and the whole plant, respectively. Finally, the 'B' value for the soybean crop varied considerably in function of the inoculated Bradyrhizobium strain, being most important when only the shoot tissue was utilised to estimate the proportion of N in the plant derived from N{sub 2} fixation. (author)

  2. Litterfall 15N abundance indicates declining soil nitrogen availability in a free-air CO2 enrichment experiment.

    Science.gov (United States)

    Garten, Charles T; Iversen, Colleen M; Norby, Richard J

    2011-01-01

    Forest productivity increases in response to carbon dioxide (CO2) enrichment of the atmosphere. However, in nitrogen-limited ecosystems, increased productivity may cause a decline in soil nitrogen (N) availability and induce a negative feedback on further enhancement of forest production. In a free-air CO2 enrichment (FACE) experiment, the response of sweetgum (Liquidambar styraciflua L.) productivity to elevated CO2 concentrations [CO2] has declined over time, but documenting an associated change in soil N availability has been difficult. Here we assess the time history of soil N availability through analysis of natural 15N abundance in archived samples of freshly fallen leaf litterfall. Litterfall delta15N declined from 1998 to 2005, and the rate of decline was significantly faster in elevated [CO2]. Declining leaf litterfall delta15N is indicative of a tighter ecosystem N cycle and more limited soil N availability. By integrating N availability over time and throughout the soil profile, temporal dynamics in leaf litterfall delta15N provide a powerful tool for documenting changes in N availability and the critical feedbacks between C and N cycles that will control forest response to elevated atmospheric CO2 concentrations.

  3. Theoretical and experimental study of 15N NMR protonation shifts.

    Science.gov (United States)

    Semenov, Valentin A; Samultsev, Dmitry O; Krivdin, Leonid B

    2015-06-01

    A combined theoretical and experimental study revealed that the nature of the upfield (shielding) protonation effect in 15N NMR originates in the change of the contribution of the sp(2)-hybridized nitrogen lone pair on protonation resulting in a marked shielding of nitrogen of about 100 ppm. On the contrary, for amine-type nitrogen, protonation of the nitrogen lone pair results in the deshielding protonation effect of about 25 ppm, so that the total deshielding protonation effect of about 10 ppm is due to the interplay of the contributions of adjacent natural bond orbitals. A versatile computational scheme for the calculation of 15N NMR chemical shifts of protonated nitrogen species and their neutral precursors is proposed at the density functional theory level taking into account solvent effects within the supermolecule solvation model. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Microbiota Transfer Therapy alters gut ecosystem and improves gastrointestinal and autism symptoms: an open-label study.

    Science.gov (United States)

    Kang, Dae-Wook; Adams, James B; Gregory, Ann C; Borody, Thomas; Chittick, Lauren; Fasano, Alessio; Khoruts, Alexander; Geis, Elizabeth; Maldonado, Juan; McDonough-Means, Sharon; Pollard, Elena L; Roux, Simon; Sadowsky, Michael J; Lipson, Karen Schwarzberg; Sullivan, Matthew B; Caporaso, J Gregory; Krajmalnik-Brown, Rosa

    2017-01-23

    Autism spectrum disorders (ASD) are complex neurobiological disorders that impair social interactions and communication and lead to restricted, repetitive, and stereotyped patterns of behavior, interests, and activities. The causes of these disorders remain poorly understood, but gut microbiota, the 10 13 bacteria in the human intestines, have been implicated because children with ASD often suffer gastrointestinal (GI) problems that correlate with ASD severity. Several previous studies have reported abnormal gut bacteria in children with ASD. The gut microbiome-ASD connection has been tested in a mouse model of ASD, where the microbiome was mechanistically linked to abnormal metabolites and behavior. Similarly, a study of children with ASD found that oral non-absorbable antibiotic treatment improved GI and ASD symptoms, albeit temporarily. Here, a small open-label clinical trial evaluated the impact of Microbiota Transfer Therapy (MTT) on gut microbiota composition and GI and ASD symptoms of 18 ASD-diagnosed children. MTT involved a 2-week antibiotic treatment, a bowel cleanse, and then an extended fecal microbiota transplant (FMT) using a high initial dose followed by daily and lower maintenance doses for 7-8 weeks. The Gastrointestinal Symptom Rating Scale revealed an approximately 80% reduction of GI symptoms at the end of treatment, including significant improvements in symptoms of constipation, diarrhea, indigestion, and abdominal pain. Improvements persisted 8 weeks after treatment. Similarly, clinical assessments showed that behavioral ASD symptoms improved significantly and remained improved 8 weeks after treatment ended. Bacterial and phagedeep sequencing analyses revealed successful partial engraftment of donor microbiota and beneficial changes in the gut environment. Specifically, overall bacterial diversity and the abundance of Bifidobacterium, Prevotella, and Desulfovibrio among other taxa increased following MTT, and these changes persisted after

  5. UPDATE of Analysis of 15N incorporation into D-alanine: A new method for tracing nitrogen uptake by bacteria (Veuger et al. 2005, Limnology and Oceanography Methods 3: 230-240)

    NARCIS (Netherlands)

    Veuger, B.; Middelburg, J.J.; Boschker, H.T.S.; Houtekamer, M.J.

    2007-01-01

    After publication of the original manuscript, the presented method has been applied in various 15N- and 13C-labeling studies to trace incorporation of 15N- and/or 13C into bacterial and total microbial biomass in different coastal sediments (Veuger et al. 2006, Veuger 2006). These applications and

  6. Automated probabilistic method for assigning backbone resonances of (13C,15N)-labeled proteins

    Energy Technology Data Exchange (ETDEWEB)

    Lukin, Jonathan A. [Carnegie Mellon University, Department of Biological Sciences (United States); Gove, Andrew P.; Talukdar, Sarosh N. [Carnegie Mellon University, Robotics Institute (United States); Ho Chien [Carnegie Mellon University, Department of Biological Sciences (United States)

    1997-02-15

    We present a computer algorithm for the automated assignment of polypeptide backbone and 13C{beta} resonances of a protein of known primary sequence. Input to the algorithm consists of cross peaks from several 3D NMR experiments: HNCA, HN(CA)CO, HN(CA)HA,HNCACB, COCAH, HCA(CO)N, HNCO, HN(CO)CA, HN(COCA)HA, and CBCA(CO)NH. Data from these experiments performed on glutamine-binding protein are analyzed statistically using Bayes' theorem to yield objective probability scoring functions for matching chemical shifts. Such scoring is used in the first stage of the algorithm to combine cross peaks from the first five experiments to form intraresidue segments of chemical shifts{l_brace}Ni,HiN,Ci{alpha},Ci{beta},C'i{r_brace}, while the latter five are combined into interresidue segments {l_brace}Ci{alpha},Ci{beta},C'i,Ni+1,HNi+1{r_brace}. Given a tentative assignment of segments,the second stage of the procedure calculates probability scores based on the likelihood of matching the chemical shifts of each segment with (i) overlapping segments; and (ii) chemical shift distributions of the underlying amino acid type (and secondary structure, if known). This joint probability is maximized by rearranging segments using a simulated annealing program,optimized for efficiency. The automated assignment program was tested using CBCANH and CBCA(CO)NH cross peaks of the two previously assigned proteins, calmodulin and CheA.The agreement between the results of our method and the published assignments was excellent. Our algorithm was also applied to the observed cross peaks of glutamine-binding protein of Escherichia coli, yielding an assignment in excellent agreement with that obtained by time-consuming, manual methods. The chemical shift assignment procedure described here should be most useful for NMR studies of large proteins, which are now feasible with the use of pulsed-field gradients and random partial deuteration of samples.

  7. Uptake of 15N labeled fertilizer in loblolly pine plantations of the southern United States

    Science.gov (United States)

    Jay E. Raymond; Thomas Fox; Brian Strahm

    2015-01-01

    Forests in the southeastern United States managed extensively (minimal silvicultural treatments) generally have low productivity rates (Fox and others 2007). Conversely, intensively managed stands have significantly increased productivity in this region, from 2 m3 ha-1 year -1 to a range of 6 to 10 m3 ha-1 year -1 (Fox and others 2007).

  8. 15N NMR chemical shifts in papaverine decomposition products

    Science.gov (United States)

    Czyrski, Andrzej; Girreser, Ulrich; Hermann, Tadeusz

    2013-03-01

    Papaverine can be easily oxidized to papaverinol, papaveraldine and 2,3,9,10-tetramethoxy-12-oxo-12H-indolo[2,1-a]isoquinolinium chloride. On addition of alkali solution the latter compound forms 2-(2-carboxy-4,5-dimethoxyphenyl)-6,7-dimethoxyisoquinolinium inner salt. Together with these structures the interesting 13-(3,4-dimethoxyphenyl)-2,3,8,9-tetramethoxy-6a-12a-diazadibenzo[a,g]fluorenylium chloride is discussed, which is formed in the Gadamer-Schulemann reaction of papaverine as a side product. This letter reports the 15N NMR spectra of the above mentioned compounds.

  9. Nitrogen-15 labeling of Crotalaria juncea green manure

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosano, Edmilson Jose; Rossetto, Raffaella [Estacao Experimental de Agronomia de Piracicaba, SP (Brazil). Centro de Acao Regional; Trivelin, Paulo Cesar Ocheuze; Muraoka, Takashi; Bendassolli, Jose Albertino [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis; Cantarella, Heitor [Instituto Agronomico de Campinas (IAC), SP (Brazil). Centro de Pesquisa e Desenvolvimento de Solos e Recursos Agroambientais; Ambrosano, Glaucia Maria Bovi [Universidade Estadual de Campinas, Piracicaba, SP (Brazil). Faculdade de Odontologia. Dept. de Odontologia Social e Bioestatistica; Tamiso, Luciano Grassi; Vieira, Felipe de Campos; Prada Neto, Ithamar [Sao Paulo Univ., Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz. Dept. de Producao Vegetal

    2003-03-01

    Most studies dealing with the utilization of {sup 15} N labeled plant material do not present details about the labeling technique. This is especially relevant for legume species since biological nitrogen fixation difficult plant enrichment. A technique was developed for labeling leguminous plant tissue with {sup 15} N to obtain labeled material for nitrogen dynamics studies. Sun hemp (Crotalaria juncea L.) was grown on a Paleudalf, under field conditions. An amount of 58.32 g of urea with 70.57{+-} 0.04 atom % {sup 15} N was sprayed three times on plants grown on eight 6-m2-plots. The labelled material presented 2.412 atom % {sup 15} N in a total dry matter equivalent to 9 Mg ha{sup -1} This degree of enrichment enables the use of the green manure in pot or field experiments requiring {sup 15} N-labeled material. (author)

  10. Covalent binding of aniline to humic substances. 2. 15N NMR studies of nucleophilic addition reactions

    Science.gov (United States)

    Thorn, K.A.; Pettigrew, P.J.; Goldenberg, W.S.; Weber, E.J.

    1996-01-01

    Aromatic amines are known to undergo covalent binding with humic substances in the environment. Although previous studies have examined reaction conditions and proposed mechanisms, there has been no direct spectroscopic evidence for the covalent binding of the amines to the functional groups in humic substances. In order to further elucidate the reaction mechanisms, the Suwannee River and IHSS soil fulvic and humic acids were reacted with 15N-labeled aniline at pH 6 and analyzed using 15N NMR spectrometry. Aniline underwent nucleophilic addition reactions with the quinone and other carbonyl groups in the samples and became incorporated in the form of anilinohydroquinone, anilinoquinone, anilide, imine, and heterocyclic nitrogen, the latter comprising 50% or more of the bound amine. The anilide and anilinohydroquinone nitrogens were determined to be susceptible to chemical exchange by ammonia. In the case of Suwannee River fulvic acid, reaction under anoxic conditions and pretreatment with sodium borohydride or hydroxylamine prior to reaction under oxic conditions resulted in a decrease in the proportion of anilinohydroquinone nitrogen incorporated. The relative decrease in the incorporation of anilinohydroquinone nitrogen with respect to anilinoquinone nitrogen under anoxic conditions suggested that inter- or intramolecular redox reactions accompanied the nucleophilic addition reactions.

  11. Compaction stimulates denitrification in an urban park soil using 15N tracing technique

    DEFF Research Database (Denmark)

    Li, Shun; Deng, Huan; Rensing, Christopher Günther T

    2014-01-01

    Soils in urban areas are subjected to compaction with accelerating urbanization. The effects of anthropogenic compaction on urban soil denitrification are largely unknown. We conducted a study on an urban park soil to investigate how compaction impacts denitrification. By using 15N labeling method...... and acetylene inhibition technique, we performed three coherent incubation experiments to quantify denitrification in compacted soil under both aerobic and anaerobic conditions. Uncompacted soil was set as the control treatment. When monitoring soil incubation without extra substrate, higher nitrous oxide (N2O......) flux and denitrification enzyme activity were observed in the compacted soil than in the uncompacted soil. In aerobic incubation with the addition of K15NO3, N2O production in the compacted soil reached 10.11 ng N h-1 g-1 as compared to 0.02 ng N h-1 g-1 in the uncompacted soil. Denitrification...

  12. Organic vs. Conventional Grassland Management: Do 15N and 13C Isotopic Signatures of Hay and Soil Samples Differ?

    Science.gov (United States)

    Klaus, Valentin H.; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Fischer, Markus; Kleinebecker, Till

    2013-01-01

    Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ15N and δ13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ15N15N plant - δ15N soil) to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ13C in hay and δ15N in both soil and hay between management types, but showed that δ13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ15N values implied that management types did not substantially differ in nitrogen cycling. Only δ13C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be efficiently used in practice

  13. Organic vs. conventional grassland management: do (15N and (13C isotopic signatures of hay and soil samples differ?

    Directory of Open Access Journals (Sweden)

    Valentin H Klaus

    Full Text Available Distinguishing organic and conventional products is a major issue of food security and authenticity. Previous studies successfully used stable isotopes to separate organic and conventional products, but up to now, this approach was not tested for organic grassland hay and soil. Moreover, isotopic abundances could be a powerful tool to elucidate differences in ecosystem functioning and driving mechanisms of element cycling in organic and conventional management systems. Here, we studied the δ(15N and δ(13C isotopic composition of soil and hay samples of 21 organic and 34 conventional grasslands in two German regions. We also used Δδ(15N (δ(15N plant - δ(15N soil to characterize nitrogen dynamics. In order to detect temporal trends, isotopic abundances in organic grasslands were related to the time since certification. Furthermore, discriminant analysis was used to test whether the respective management type can be deduced from observed isotopic abundances. Isotopic analyses revealed no significant differences in δ(13C in hay and δ(15N in both soil and hay between management types, but showed that δ(13C abundances were significantly lower in soil of organic compared to conventional grasslands. Δδ(15N values implied that management types did not substantially differ in nitrogen cycling. Only δ(13C in soil and hay showed significant negative relationships with the time since certification. Thus, our result suggest that organic grasslands suffered less from drought stress compared to conventional grasslands most likely due to a benefit of higher plant species richness, as previously shown by manipulative biodiversity experiments. Finally, it was possible to correctly classify about two third of the samples according to their management using isotopic abundances in soil and hay. However, as more than half of the organic samples were incorrectly classified, we infer that more research is needed to improve this approach before it can be

  14. Measuring denitrification after grassland renewal and grassland conversion to cropland by using the 15N gas-flux method

    Science.gov (United States)

    Buchen, Caroline; Eschenbach, Wolfram; Flessa, Heinz; Giesemann, Anette; Lewicka-Szczebak, Dominika; Well, Reinhard

    2015-04-01

    Denitrification, the reduction of oxidized forms of inorganic N to N2O and N2 is an important pathway of gaseous nitrogen losses. Measuring denitrification, especially the reduction of N2O to N2, expressed in the product ratio (N2O/(N2O + N2)), is rather difficult and hence rarely performed under field conditions. But using the 15N gas-flux method allows determining N transformation processes in their natural environment. In order to develop effective climate mitigation strategies understanding the N2O source is essential. We used the 15N gas-flux method to determine N2O and N2 emissions following grassland renewal and conversion techniques. Therefore we selected three different treatments: control (C), mechanical grassland renovation (GR) (autumn 2013) and grassland conversion to maize (GM) (spring 2014) from field plot trials on two different sites (Histic Gleysoil and Plaggic Anthrosol) near Oldenburg, Lower Saxony, Germany. We applied 15N labeled KNO3- (60 atom. % 15N) at a rate equivalent to common farming practices (150 kg N*ha-1) using needle injection of fertilizer solution in three different depths (10 cm, 15 cm, 20 cm) for homogeneous soil labeling up to 30 cm in microplots. During the first 10 days after application (May 2014) gas flux measurements from closed chambers were performed every second day and then weekly following a period of 8 weeks. Gas samples were analyzed for δ15N of N2 and N2O by IRMS according to Lewicka-Szczebak et al. (2013). Concentration and 15N enrichment of NO3- in soil water was determined on weekly samples using the SPIN-MAS technique (Stange et al. 2007). Fluxes of N2 and N2O evolved from the 15N labeled soil nitrogen pool were calculated using the equations of Spott et al. (2006). Peak events of N2 and N2O emissions occurred during the first 10 days of measurement, showing differences in soil types, as well as treatment variations. N2 fluxes up to 178 g*ha-1*day-1 and N2O fluxes up to 280 g*ha-1*day-1 were measured on the

  15. The influence of fish cage culture on δ13C and δ15N of filter-feeding Bivalvia (Mollusca).

    Science.gov (United States)

    Benedito, E; Figueroa, L; Takeda, A M; Manetta, G I

    2013-11-01

    The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ13C and δ15N in Corbicula fluminea (Mollusca; Bivalvia) and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP). Samples of specimens of the bivalve filterer C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C) for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ13C) and nitrogen (δ15N) isotopic value analysis in a mass spectrometer. There were significant differences in the δ13C and δ15N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ13C and δ15N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem.

  16. The influence of fish cage culture on δ13C and δ15N of filter-feeding Bivalvia (Mollusca

    Directory of Open Access Journals (Sweden)

    E. Benedito

    Full Text Available The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ13C and δ15N in Corbicula fluminea (Mollusca; Bivalvia and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP. Samples of specimens of the bivalve filterer C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ13C and nitrogen (δ15N isotopic value analysis in a mass spectrometer. There were significant differences in the δ13C and δ15N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ13C and δ15N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem.

  17. Contrasting food web linkages for the grazing pathway in 3 temperate forested streams using {sup 15}N as a tracer

    Energy Technology Data Exchange (ETDEWEB)

    Tank, J.L.; Mulholland, P.J.; Meyer, J.L.; Bowden, W.B.; Webster, J.R.; Peterson, B.J.

    1998-11-01

    Nitrogen is a critical element controlling the productivity and dynamics of stream ecosystems and many streams are limited by the supply of biologically available nitrogen. The authors are learning more about the fate of inorganic nitrogen entering streams through {sup 15}N tracer additions. The Lotic Intersite Nitrogen Experiment (LINX) is studying the uptake, cycling, and fate of {sup 15}N-NH{sub 4} in the stream food web of 10 streams draining different biomes. Using the {sup 15}N tracer method and data from 3 sites in the study, the authors can differentiate patterns in the cycling of nitrogen through the grazing pathway (N from the epilithon to grazing macroinvertebrates) for 3 temperate forested streams. Here, they quantify the relationship between the dominant grazer and its proposed food resource, the epilithon, by comparing {sup 15}N levels of grazers with those of the epilithon, as well as the biomass, nitrogen content, and chlorophyll a standing stocks of the epilithon in 3 streams.

  18. Amyloid Hydrogen Bonding Polymorphism Evaluated by (15)N{(17)O}REAPDOR Solid-State NMR and Ultra-High Resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry.

    Science.gov (United States)

    Wei, Juan; Antzutkin, Oleg N; Filippov, Andrei V; Iuga, Dinu; Lam, Pui Yiu; Barrow, Mark P; Dupree, Ray; Brown, Steven P; O'Connor, Peter B

    2016-04-12

    A combined approach, using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and solid-state NMR (Nuclear Magnetic Resonance), shows a high degree of polymorphism exhibited by Aβ species in forming hydrogen-bonded networks. Two Alzheimer's Aβ peptides, Ac-Aβ(16-22)-NH2 and Aβ(11-25), selectively labeled with (17)O and (15)N at specific amino acid residues were investigated. The total amount of peptides labeled with (17)O as measured by FTICR-MS enabled the interpretation of dephasing observed in (15)N{(17)O}REAPDOR solid-state NMR experiments. Specifically, about one-third of the Aβ peptides were found to be involved in the formation of a specific >C═(17)O···H-(15)N hydrogen bond with their neighbor peptide molecules, and we hypothesize that the rest of the molecules undergo ± n off-registry shifts in their hydrogen bonding networks.

  19. Spatial Patterns of Plant δ13C and δ15N Along a Topoedaphic Gradient in a Subtropical Savanna Landscape

    Science.gov (United States)

    Bai, E.; Boutton, T. W.; Liu, F.; Wu, B.; Archer, S. R.

    2005-12-01

    δ13C and δ15N values of plants are powerful tools in physiological ecology, ecosystem science, and global biogeochemistry, yet we know relatively little about their variation and controls at the landscape scale. In this study, we investigated landscape-scale spatial variations in the foliar isotopic composition of 3 woody plant species across a 308 m topoedaphic gradient, along which soil texture and plant resources (water and nitrogen availability) varied from upland (86 m) to lowland (84 m) portions of the landscape. The study was conducted in a subtropical savanna at the La Copita Research Area, approximately 60 km west of Corpus Christi, TX. Foliar δ13C, δ15N, leaf nitrogen concentration ([N]), and specific leaf area (SLA) were measured on all individuals of Prosopis glandulosa, Condalia hookeri, and Zanthoxylum fagara present within a belt transect 308 m long x 12 m wide. Soil texture, available soil moisture, and total N were measured at 1 m intervals along the center-line of the belt transect. Clay content, available soil moisture, and soil total N were all negatively correlated with elevation along the transect. Leaf δ13C and δ15N values for all 3 species increased by 1-4 o/oo with decreasing elevation along the transect. Contrary to theory and previous studies, δ13C values were highest where soil water was most available, suggesting that some other variable could be overriding or interacting with water availability. Foliar [N] appeared to exert the strongest control over landscape-level variation, and was positively correlated with δ13C of all species (R 2 = 0.58, pCondalia were positively correlated with leaf [N] and soil water availability; however, these relationships were absent for Prosopis, an N-fixing tree legume. We speculate that the relationship between δ15N and leaf [N] and soil water may reflect the fact that plants with high δ15N values occurred on lower-lying portions of the landscape with relatively high N-transformation rates

  20. Using δ15N of Chironomidae as an index of nitrogen sources and processing within watersheds as part of EPA's National Aquatic Resource Surveys

    Science.gov (United States)

    Brooks, J. R.; Compton, J.; Herlihy, A.; Sobota, D. J.; Stoddard, J.; Weber, M.

    2014-12-01

    Nitrogen (N) removal in watersheds is an important regulating ecosystem service that can help reduce N pollution in the nation's waterways. However, processes that remove N such as denitrification are generally determined at point locations. Measures that integrate N processing within watersheds and over time would be particularly useful for assessing the degree of this vital service. Because most N removal processes isotopically enrich the N remaining, δ15N from basal food-chain organisms in aquatic ecosystems can provide information on watershed N processing. As part of EPA's National Aquatic Resource Surveys (NARS), we measured δ15N of Chironomidae in lakes, rivers and streams because these larval aquatic insects were found in abundance in almost every lake and stream in the U.S. Using information on nitrogen loading to the watershed, and total N concentrations within the water, we assessed when elevated chironomid δ15N would indicate N removal rather than possible enriched sources of N. Chironomid δ15N values ranged from -4 to +20 ‰, and were higher in rivers and streams than in lakes (median = 7.6 ‰ vs. 4.8 ‰, respectively), indicating that N was processed to a greater degree in lotic chironomids than in lentic ones. For both, δ15N increased with watershed-level agricultural land cover and N loading, and decreased as precipitation increased. In rivers and streams with high synthetic N loading, we found lower N concentrations in streams with higher chironomid δ15N values, suggesting greater N removal. At low levels of synthetic N loading, the pattern reversed, and streams with enriched chironomid δ15N had higher N concentrations, suggesting enriched sources such as manure or sewage. Our results indicate that chironomid δ15N values can provide valuable information about watershed-level N inputs and processing for national water quality monitoring efforts.

  1. Studies of lake environments using stable isotope ratios of nitrogen (δ15N) and carbon (δ13C)

    Science.gov (United States)

    Iizumi, Yoshiko

    Increasing numbers of studies have recently used stable isotopes of nitrogen (δ15N) and carbon (δ13C) to clarify the source of nutrients in lake water and sediments, the structure and energy flow of food webs, the bioaccumulation and biomagnification of hazardous chemicals in aquatic animals, and temporal trends in lake environments. In lake research in particular, the analysis of δ15N and δ13C is a powerful tool in analyzing the structure of the food web and energy flows, as well as the bioaccumulation and biomagnification of toxic chemicals in aquatic animals. Furthermore, the integration of data on food webs, stable isotope ratios, and environmental geochemistry can be useful in evaluating the risks of exposure to environmental contaminants. It is hoped that further research on lake environments using stable isotopic methods can be performed with the aim of conserving water quality and aquatic ecosystems.

  2. The use of 32P and 15N to Estimate Fertilizer Efficiency in Oil Palm

    Directory of Open Access Journals (Sweden)

    Elsje L. Sisworo

    2004-01-01

    Full Text Available Oil palm has become an important commodity for Indonesia reaching an area of 2.6 million ha at the end of 1998. It is mostly cultivated in highly weathered acid soil usually Ultisols and Oxisols which are known for their low fertility, concerning the major nutrients like N and P. This study most conducted to search for the most active root-zone of oil palm and applied urea fertilizer at such soils to obtain high N-efficiency. Carrier free KH232PO4 solution was used to determine the active root-zone of oil palm by applying 32P around the plant in twenty holes. After the most active root-zone have been determined, urea in one, two and three splits were respectively applied at this zone. To estimate N-fertilizer efficiency of urea labelled 15N Ammonium Sulphate was used by adding them at the same amount of 16 g 15N plant-1. This study showed that the most active root-zone was found at a 1.5 m distance from the plant-stem and at 5 cm soil depth. For urea the highest N-efficiency was obtained from applying it at two splits. The use of 32P was able to distinguish several root zones: 1.5 m – 2.5 m from the plant-stem at a 5 cm and 15 cm soil depth. Urea placed at the most active root-zone, which was at a 1.5 m distance from the plant-stem and at a 5 cm depth in one, two, and three splits respectively showed difference N-efficiency. The highest N-efficiency of urea was obtained when applying it in two splits at the most active root-zone.

  3. Depth-dependence in stable isotope ratio δ 15N of benthic POM consumers: The role of particle dynamics and organism trophic guild

    Science.gov (United States)

    Mintenbeck, K.; Jacob, U.; Knust, R.; Arntz, W. E.; Brey, T.

    2007-06-01

    The stable nitrogen isotope ratio (δ 15N) is an established indicator of trophic hierarchy in marine food-web studies. Most of these studies presume that spatial variation in the primary food source is negligible, although a water-depth-related increase in δ 15N of particulate organic matter (POM) has been found in many systems. We used the high-Antarctic Weddell Sea shelf and slope ecosystem to test whether such a depth-related change in δ 15N is reflected at higher trophic levels, i.e., benthic consumers of POM. In suspension feeders (SF) we found a significant increase in δ 15N with water depth of up to 9.8‰, whereas in deposit feeders (DF) a depth effect was barely detectable. Particle-size preferences of the two feeding guilds combined with particle-size-dependent sinking velocities and biogeochemical reworking of POM are discussed as the major causes of these differences. It is essential to marine food-web studies to take into account the general depth effect on POM δ 15N as well as potential feeding-guild-specific differences in the response of POM consumer tissue δ 15N to avoid serious bias and misinterpretation of stable-isotope-based trophic information.

  4. Regional patterns in foliar 15N across a gradient of nitrogen deposition in the northeastern US

    Science.gov (United States)

    Linda H. Pardo; Steven G. McNulty; Johnny L. Boggs; Sara Duke

    2007-01-01

    Recent studies have demonstrated that natural abundance 15N can be a useful tool for assessing nitrogen saturation, because as nitrification and nitrate loss increase, d15N of foliage and soil also increases. We measured foliar d15N at 11 high-elevation spruce-fir stands along an N deposition gradient...

  5. 15N NMR investigation of the covalent binding of reduced TNT amines to soil humic acid, model compounds, and lignocellulose

    Science.gov (United States)

    Thorn, K.A.; Kennedy, K.R.

    2002-01-01

    The five major reductive degradation products of TNT-4ADNT (4-amino-2,6-dinitrotoluene), 2ADNT (2-amino-4,6-dinitrotoluene), 2,4DANT (2,4-diamino-6-nitrotoluene), 2,6DANT (2,6-diamino-4-nitrotoluene), and TAT (2,4,6-triaminotoluene)-labeled with 15N in the amine positions, were reacted with the IHSS soil humic acid and analyzed by 15N NMR spectrometry. In the absence of catalysts, all five amines underwent nucleophilic addition reactions with quinone and other carbonyl groups in the soil humic acid to form both heterocyclic and nonheterocyclic condensation products. Imine formation via 1,2-addition of the amines to quinone groups in the soil humic acid was significant with the diamines and TAT but not the monoamines. Horseradish peroxidase (HRP) catalyzed an increase in the incorporation of all five amines into the humic acid. In the case of the diamines and TAT, HRP also shifted the binding away from heterocyclic condensation product toward imine formation. A comparison of quantitative liquid phase with solid-state CP/MAS 15N NMR indicated that the CP experiment underestimated imine and heterocyclic nitrogens in humic acid, even with contact times optimal for observation of these nitrogens. Covalent binding of the mono- and diamines to 4-methylcatechol, the HRP catalyzed condensation of 4ADNT and 2,4DANT to coniferyl alcohol, and the binding of 2,4DANT to lignocellulose with and without birnessite were also examined.

  6. Applicability of a “Multi-Stage Pulse Labeling” 15N Approach to Phenotype N Dynamics in Maize Plant Components during the Growing Season

    Directory of Open Access Journals (Sweden)

    Amanda de Oliveira Silva

    2017-08-01

    Full Text Available HighlightsThis work utilizes “multi-stage pulse labeling” 15N applications, primarily during reproductive growth stages, as a phenotyping strategy to identify maize hybrids with superior N use efficiency (NUE under low N conditions.Research using labeled isotopic N (15N can precisely quantify fertilizer nitrogen (N uptake and organ-specific N allocation in field crops such as maize (Zea mays L.. The overall research objective was to study plant N uptake patterns potentially correlated with N use efficiency (NUE in field-grown maize hybrids using a “multi-stage pulse labeling” 15N phenotyping strategy with an emphasis on the reproductive period. Five hybrids varying in NUE were compared under zero N fertilizer application (0N plus a moderate rate of 112 kg N ha−1 (112N in 2013 (2 locations and 2014 growing seasons. The equivalent of 3.2 (2013 to 2.1 (2014 kg of 15N ha−1, as labeled Ca(15NO32, was injected into soil on both sides of consecutive plants at multiple stages between V14 and R5. Aboveground plant biomass was primarily collected in short-term intervals (4–6 days after each 15N application in both years, and following a single long-term interval (at R6 after 15N injection at R1 in 2014. Averaged across hybrids and site-years, the moderate N rate (112N increased absolute 15N uptake at all stages; however, plants in the 0N treatment allocated proportionally more 15N to reproductive organs. Before flowering, short-term recovery of 15N (15Nrec totaled ~0.30 or 0.40 kg kg−1 of the 15N applied, and ~50% of that accumulated 15Nu was found in leaves and 40% in stems. After flowering, plant 15Nrec totaled ~0.30 kg kg−1 of 15N applied, and an average 30% of accumulated 15Nu was present in leaves, 17% in stems, and the remainder—usually the majority—in ears. At the R5 stage, despite a declining overall rate of 15N uptake per GDD thermal unit, plant 15Nrec represented ~0.25 kg kg−1 of 15N applied, of which ~65% was allocated

  7. Resolving the bulk δ 15N values of ancient human and animal bone collagen via compound-specific nitrogen isotope analysis of constituent amino acids

    Science.gov (United States)

    Styring, Amy K.; Sealy, Judith C.; Evershed, Richard P.

    2010-01-01

    Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and trophic positions within contemporary and ancient ecosystems. In order to assess more fully the dietary contributions to human tissue isotope values, a greater understanding of the complex biochemical and physiological factors which underpin bulk collagen δ 15N values is necessary. Determinations of δ 15N values of the individual amino acids which constitute bone collagen are necessary to unravel these relationships, since different amino acids display different δ 15N values according to their biosynthetic origins. A range of collagen isolates from archaeological faunal and human bone ( n = 12 and 11, respectively), representing a spectrum of terrestrial and marine protein origins and diets, were selected from coastal and near-coastal sites at the south-western tip of Africa. The collagens were hydrolysed and δ 15N values of their constituent amino acids determined as N-acetylmethyl esters (NACME) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The analytical approach employed accounts for 56% of bone collagen nitrogen. Reconstruction of bulk bone collagen δ 15N values reveals a 2‰ offset from bulk collagen δ 15N values which is attributable to the δ 15N value of the amino acids which cannot currently be determined by GC-C-IRMS, notably arginine which comprises 53% of the nitrogen unaccounted for (23% of the total nitrogen). The δ 15N values of individual amino acids provide insights into both the contributions of various amino acids to the bulk δ 15N value of collagen and the factors influencing trophic position and the nitrogen source at the base of the food web. The similarity in the δ 15N values of alanine, glutamate, proline and hydroxyproline reflects the common origin of their amino groups from glutamate. The depletion in the δ 15N value of threonine with increasing trophic level indicates a fundamental difference between

  8. Exogenous proline relieves growth inhibition caused by NaCl in petunia cells: Metabolism of L-( sup 15 M)-proline followed by sup 15 N NMR

    Energy Technology Data Exchange (ETDEWEB)

    Heyser, J.W.; Chacon, M.J. (Los Alamos National Lab., NM (USA))

    1989-04-01

    Exogenous proline stimulated the growth of Petunia hybrida cells on 195 mM NaCl 10-fold as compared with cells grown on 195 mM CaCl medium minus proline. L-({sup 15}N)-proline was fed to cells growing on 0 and 195 mM CaCl, and its metabolism was followed by {sup 15}N NMR analysis of cell extracts. Total proline and amino acids were determined by ninhydrin assay. Proline and primary amino acids were easily resolved in NMR spectra and the amount of {sup 15}N-label which remained in proline was determined. Reduced catabolism of proline in cells grown on NaCl was evident. The role of exogenous proline in conferring increased NaCl tolerance in this nonhalophyte will be discussed.

  9. Fate of nitrogen (15N from velvet bean in the soil-plant system

    Directory of Open Access Journals (Sweden)

    Scivittaro Walkyria Bueno

    2004-01-01

    Full Text Available Because of their potential for N2 biological fixation, legumes are an alternative source of nitrogen to crops, and can even replace or supplement mineral fertilization. A greenhouse experiment was carried out to evaluate temporal patterns of velvet bean (Mucuna aterrima green manure release of nitrogen to rice plants, and to study the fate of nitrogen from velvet bean in rice cultivation. The isotopic dilution methodology was used. Treatments consisted of a control and 10 incubation periods of soil fertilized with 15N-labeled velvet bean (0, 20, 40, 60, 90, 120, 150, 180, 210, and 240 days. The plant material was previously chopped, sifted (10 mm mesh sieve and oven-dried (65ºC. Incubation of the plant material (2.2 g kg-1 soil was initiated by the longest period, in order to synchronize the planting of the test crop, rice (Oryza sativa, at time zero for all treatments. Green manure incorporation promoted increases in rice dry matter yield and nitrogen uptake. These variables showed maximum values at incubation periods of 38 and 169 days, respectively. Green manure nitrogen utilization by rice plants was highest at an incubation period corresponding to 151 days. More than 60% of the green manure nitrogen remained in the soil after rice cultivation. The highest green manure nitrogen recovery from the soil-plant system occurred at an incubation period equivalent to 77 days.

  10. Fate of nitrogen ({sup 15}N) from velvet bean in the soil-plant system

    Energy Technology Data Exchange (ETDEWEB)

    Scivittaro, Walkyria Bueno [Empresa Brasileira de Pesquisa Agropecuaria, Pelotas, RS (Brazil). Clima Temperado; Muraoka, Takashi; Boaretto, Antonio Enedi; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura, Piracicaba, SP (Brazil). Lab. de Fertilidade do Solo]. E-mail: wbscivit@cpact.embrapa.br

    2004-04-01

    Because of their potential for N{sub 2} biological fixation, legumes are an alternative source of nitrogen to crops, and can even replace or supplement mineral fertilization. A greenhouse experiment was carried out to evaluate temporal patterns of velvet bean (Mucuna aterrima) green manure release of nitrogen to rice plants, and to study the fate of nitrogen from velvet bean in rice cultivation. The isotopic dilution methodology was used. Treatments consisted of a control and 10 incubation periods of soil fertilized with {sup 15}N-labeled velvet bean (0, 20, 40, 60, 90, 120, 150, 180, 210, and 240 days). The plant material was previously chopped, sifted (10 mm mesh sieve) and oven-dried (65 deg C). Incubation of the plant material (2.2 g kg{sup -1} soil) was initiated by the longest period, in order to synchronize the planting of the test crop, rice (Oryza sativa), at time zero for all treatments. Green manure incorporation promoted increases in rice dry matter yield and nitrogen uptake. These variables showed maximum values at incubation periods of 38 and 169 days, respectively. Green manure nitrogen utilization by rice plants was highest at an incubation period corresponding to 151 days. More than 60% of the green manure nitrogen remained in the soil after rice cultivation. The highest green manure nitrogen recovery from the soil-plant system occurred at an incubation period equivalent to 77 days. (author)

  11. Estimating δ15N fractionation and adjusting the lipid correction equation using Southern African freshwater fishes.

    Directory of Open Access Journals (Sweden)

    Geraldine C Taylor

    Full Text Available Stable isotope analysis is an important tool for characterising food web structure; however, interpretation of isotope data can often be flawed. For instance, lipid normalisation and trophic fractionation values are often assumed to be constant, but can vary considerably between ecosystems, species and tissues. Here, previously determined lipid normalisation equations and trophic fractionation values were re-evaluated using freshwater fish species from three rivers in the Upper Zambezian floodplain ecoregion in southern Africa. The parameters commonly used in lipid normalisation equations were not correct for the 18 model species (new D and I parameters were estimated as D = 4.46‰ [95% CI: 2.62, 4.85] and constant I = 0 [95% CI: 0, 0.17]. We suggest that future isotopic analyses on freshwater fishes use our new values if the species under consideration do not have a high lipid content in their white muscle tissue. Nitrogen fractionation values varied between species and river basin; however, the average value closely matched that calculated in previous studies on other species (δ15N fractionation factor of 3.37 ± 1.30 ‰. Here we have highlighted the need to treat stable isotope data correctly in food web studies to avoid misinterpretation of the data.

  12. Application of {sup 13}C and {sup 15}N stable isotope probing to characterize RDX degrading microbial communities under different electron-accepting conditions

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Kun-Ching; Lee, Do Gyun [Zachry Department of Civil Engineering, Texas A& M University, College Station, TX 77843-3136 (United States); Fuller, Mark E.; Hatzinger, Paul B.; Condee, Charles W. [CB& I Federal Services, Lawrenceville, NJ (United States); Chu, Kung-Hui, E-mail: kchu@civil.tamu.edu [Zachry Department of Civil Engineering, Texas A& M University, College Station, TX 77843-3136 (United States)

    2015-10-30

    Highlights: • SIP characterized RDX-degrading communities under different e-accepting conditions. • Dominant RDX degradation pathways differed under different e-accepting conditions. • More complete detoxification of RDX occurred under methanogenic and sulfate-reducing conditions than under manganese(IV) and iron(III)-reducing conditions. - Abstract: This study identified microorganisms capable of using the explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) or its metabolites as carbon and/or nitrogen sources under different electron-accepting conditions using {sup 13}C and {sup 15}N stable isotope probing (SIP). Mesocosms were constructed using groundwater and aquifer solids from an RDX-contaminated aquifer. The mesocosms received succinate as a carbon source and one of four electron acceptors (nitrate, manganese(IV), iron(III), or sulfate) or no additional electron acceptor (to stimulate methanogenesis). When RDX degradation was observed, subsamples from each mesocosm were removed and amended with {sup 13}C{sub 3}- or ring-{sup 15}N{sub 3}-, nitro-{sup 15}N{sub 3}-, or fully-labeled {sup 15}N{sub 6}-RDX, followed by additional incubation and isolation of labeled nucleic acids. A total of fifteen 16S rRNA sequences, clustering in α- and γ-Proteobacteria, Clostridia, and Actinobacteria, were detected in the {sup 13}C-DNA fractions. A total of twenty seven sequences were derived from different {sup 15}N-DNA fractions, with the sequences clustered in α- and γ-Proteobacteria, and Clostridia. Interestingly, sequences identified as Desulfosporosinus sp. (in the Clostridia) were not only observed to incorporate the labeled {sup 13}C or {sup 15}N from labeled RDX, but also were detected under each of the different electron-accepting conditions. The data suggest that {sup 13}C- and {sup 15}N-SIP can be used to characterize microbial communities involved in RDX biodegradation, and that the dominant pathway of RDX biodegradation may differ under different

  13. Quantification of the contribution of biological nitrogen fixation to tropical green manure crops and the residual benefit to a subsequent maize crop using 15N-isotope techniques.

    Science.gov (United States)

    Ramos, M G; Villatoro, M A; Urquiaga, S; Alves, B J; Boddey, R M

    2001-10-04

    In this study the contribution of biological N2 fixation (BNF) to leguminous green manures was quantified in the field at different sites with different 15N methodologies. In the first experiment, conducted on a Terra Roxa soil in Cuba, the BNF contribution to three legumes (Crotalaria juncea, Mucuna aterrima and Canavalia ensiformis) was quantified by applying 15N-labelled ammonium sulphate to the soil. The second experiment was planted in a very low fertility sandy soil near Rio de Janeiro, and the 15N natural abundance technique was applied to quantify BNF in C. juncea, M. niveum and soybean. In both studies the advantages of using several non-N2-fixing reference plants was apparent and despite the much greater accumulation of the C. juncea in the experiment performed on the fertile soil of Cuba, the above ground contributions of BNF at both sites were similar (40-80 kg N x ha(-1)) and greater than for the other legumes. In a further experiment the possible contribution of root-derived N to the soil/plant system of two of the legumes was quantified using a 15N-leaf-labelling technique performed in pots. The results of this study suggested that total below-ground N could constitute as much as 39 to 49% of the total N accumulated by the legume crops.

  14. Microbial fermentative preparation of L-(/sup 15/N/sub 2/)lysine and its tracer: application to serum amino acid kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Irving, C.S.; Cooney, C.L.; Brown, L.T.; Gold, D.; Gordon, J.; Klein, P.D.

    1983-05-01

    The microorganism Brevibacterium flavium 21129 has been used to produce multigram batches of L-(/sup 15/N/sub 2/)lysine of high purity and isotopic enrichment by supplementation of the growth medium with (/sup 15/NH/sub 4/)/sub 2/SO/sub 4/ of 98.0 atom% excess. The doubly /sup 15/N-labeled lysine can be detected at dilutions 10 times greater than singly labeled lysine when isotope dilution curves are analyzed by gas chromatography-mass spectrometry. This enhanced sensitivity permits kinetic measurements of plasma free-lysine isotope content over a 300-fold dilution during 6 h following a single oral bolus of 5 mg/kg body wt. This inexpensive preparation method lends itself to the production of highly useful biochemical compounds for kinetic studies of human nutrition.

  15. [15N-flow after in sacco incubation and feeding of sheep and goats with untreated wheat straw or straw treated with 15N horse urine].

    Science.gov (United States)

    Schubert, R; Flachowsky, G; Bochröder, B

    1994-01-01

    Chopped wheat straw was homogeneously mixed with urine of horses (5.75 gN per 1, 16.88 atom-% 15N-excess) and airtightly stored in plastic containers for 6 months. Three rumen fistulated sheep and goats each were fed with untreated or urine treated straw. Concentrate was added to straw. Untreated and urine treated straw were given in nylon bags and incubated in the rumen of sheep and goats for 1, 3, 6, 12, 24, 48 and 72 hours. A three compartment exponential function was used to fit the measurements of 15N-excess and 15N-amount of bag content. The curves and the calculated partial Y-values of the three compartments show the inflow and outflow of 15N into or from the bags and allow conclusions about the binding of urine N. Most N of urine was not compactly bound by straw during storage. Primarily microbial N was attached to the straw in the rumen. About 6% of urine N were bound more compact to the straw. Similar curves were calculated for 15N-excess and 15N-amount of nylon bags. The curves allow conclusions about tracer flows without quantitative knowledge. There were no significant differences between animal species.

  16. The use of sedimentary %C, %N, {delta} {sup 15}N, and Pb concentrations to assess historical changes in anthropogenic influence on Portuguese estuaries

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Paula [IMAR - Institute of Marine Research, Department of Botany, University of Coimbra, Travessa Martim de Freitas, 3000 Coimbra (Portugal)]. E-mail: pcastro@ci.uc.pt; Valiela, Ivan [Boston University Marine Program, Marine Biological Laboratory, 7 MBL Street, Woods Hole, 02543 MA (United States); Freitas, Helena [IMAR - Institute of Marine Research, Department of Botany, University of Coimbra, Travessa Martim de Freitas, 3000 Coimbra (Portugal)

    2007-06-15

    Vertical profiles of C, N, {delta} {sup 15}N and Pb were measured in the Mondego and Mira estuaries as markers that conveyed notions as to the relative influence of anthropogenic influence over the past decades. Recent carbon changes in both estuaries may reflect changes in estuarine productivity, probably as a consequence of sediment reworking and erosion, and also of losses in salt marsh area and dwarf eelgrass beds. {delta} {sup 15}N values began to diverge considerably before the %C and %N and were higher in Mondego. {delta} {sup 15}N signatures detected N enrichment at relatively low rates, and indicated that Mondego received more enriched N than Mira. Lead concentrations differed between estuaries, with higher concentrations in Mondego. The secular increase in %N, Pb, and {delta} {sup 15}N signatures was significantly related to human density in the watersheds of the estuaries and were sensitive indicators of anthropogenic activity. - The variables C, %N, {delta} {sup 15}N, and Pb were reliable sediment sentinels that reflected the level of anthropogenic influence in the past decades in estuarine ecosystems.

  17. /sup 15/N-Ammonia assimilation, 2-oxoglutarate transport, and glutamate export in spinach chloroplasts in the presence of dicarboxylates in the light

    Energy Technology Data Exchange (ETDEWEB)

    Woo, K.C.; Boyle, F.A.; Flugge, I.U.; Heldt, H.W.

    1987-11-01

    The direct incorporation of /sup 15/NH/sub 4/Cl into amino acids in illuminated spinach (Spinacia oleracea L.) chloroplasts in the presence of 2-oxoglutarate plus malate was determined. The amido-N of glutamine was the most highly labeled N-atom during /sup 15/NH/sub 4/ assimilation in the presence of malate. In 4 minutes the /sup 15/N-label of the amido-N of glutamine was 37% enriched. In contrast, values obtained for both the N-atom of glutamate and the amino-N of glutamine were only about 20% while that of the N-atom of aspartate was only 3%. The addition of malate during the assimilation of /sup 15/NH/sub 4/Cl and Na/sup 15/NO/sub 2/ greatly increased the /sup 15/N-label into glutamine but did not qualitatively change the order of the incorporation of /sup 15/N-label into all the amino acids examined. This evidence indicates the direct involvement of the glutamine synthetase/glutamate synthase pathway for ammonia and nitrite assimilation in isolated chloroplasts. The addition of malate or succinate during ammonia assimilation also led to more than 3-fold increase in (/sup 14/C)2-oxoglutarate transport into the chloroplast as well as an increase in the export of (/sup 14/C)glutamate out of the chloroplast. Little (/sup 14/C)glutamine was detected in the medium of the chloroplast preparations. The stimulation of /sup 15/N-incorporation and (/sup 14/C)glutamate export by malate could be directly attributed to the increase in 2-oxoglutarate transport activity (via the 2-oxoglutarate translocator) observed in the presence of exogenous malate.

  18. /sup 15/N/sub 2/ diffusion in soil during biological dinitrogen fixation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, M.P. (Lyon-1 Univ., 69 - Villeurbanne (France). Dept. de Biologie Vegetale); Warembourg, F.R. (Centre National de la Recherche Scientifique, 34 - Montpellier (France). Centre d' Etudes Phytosociologiques et Ecologiques Louis-Emberger)

    1983-01-01

    The kinetic of /sup 15/N/sub 2/ diffusion has been measured in a system similar to that for the estimation of N/sub 2/ fixation in plant microorganism associations cultivated in soil. The /sup 15/N/sub 2/ enrichment of the soil atmosphere reached an homogenous value one hour after injection of /sup 15/N/sub 2/ and is identical to that obtained by calculation, indicating that no adsorption occurs in the soil particles.

  19. Redox-controlled backbone dynamics of human cytochrome c revealed by {sup 15}N NMR relaxation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Koichi [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Kamiya, Masakatsu [Graduate School of Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Uchida, Takeshi [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan); Kawano, Keiichi [Graduate School of Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810 (Japan); Ishimori, Koichiro, E-mail: koichiro@sci.hokudai.ac.jp [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2010-07-23

    Research highlights: {yields} The dynamic parameters for the backbone dynamics in Cyt c were determined. {yields} The backbone mobility of Cyt c is highly restricted due to the covalently bound heme. {yields} The backbone mobility of Cyt c is more restricted upon the oxidation of the heme. {yields} The redox-dependent dynamics are shown in the backbone of Cyt c. {yields} The backbone dynamics of Cyt c would regulate the electron transfer from Cyt c. -- Abstract: Redox-controlled backbone dynamics in cytochrome c (Cyt c) were revealed by 2D {sup 15}N NMR relaxation experiments. {sup 15}N T{sub 1} and T{sub 2} values and {sup 1}H-{sup 15}N NOEs of uniformly {sup 15}N-labeled reduced and oxidized Cyt c were measured, and the generalized order parameters (S{sup 2}), the effective correlation time for internal motion ({tau}{sub e}), the {sup 15}N exchange broadening contributions (R{sub ex}) for each residue, and the overall correlation time ({tau}{sub m}) were estimated by model-free dynamics formalism. These dynamic parameters clearly showed that the backbone dynamics of Cyt c are highly restricted due to the covalently bound heme that functions as the stable hydrophobic core. Upon oxidation of the heme iron in Cyt c, the average S{sup 2} value was increased from 0.88 {+-} 0.01 to 0.92 {+-} 0.01, demonstrating that the mobility of the backbone is further restricted in the oxidized form. Such increases in the S{sup 2} values were more prominent in the loop regions, including amino acid residues near the thioether bonds to the heme moiety and positively charged region around Lys87. Both of the regions are supposed to form the interaction site for cytochrome c oxidase (CcO) and the electron pathway from Cyt c to CcO. The redox-dependent mobility of the backbone in the interaction site for the electron transfer to CcO suggests an electron transfer mechanism regulated by the backbone dynamics in the Cyt c-CcO system.

  20. Efficient production of (2)H, (13)C, (15)N-enriched industrial enzyme Rhizopus chinensis lipase with native disulfide bonds.

    Science.gov (United States)

    Zhang, Meng; Yu, Xiao-Wei; Swapna, G V T; Xiao, Rong; Zheng, Haiyan; Sha, Chong; Xu, Yan; Montelione, Gaetano T

    2016-07-13

    In order to use most modern methods of NMR spectroscopy to study protein structure and dynamics, isotope-enriched protein samples are essential. Especially for larger proteins (>20 kDa), perdeuterated and Ile (δ1), Leu, and Val methyl-protonated protein samples are required for suppressing nuclear relaxation to provide improved spectral quality, allowing key backbone and side chain resonance assignments needed for protein structure and dynamics studies. Escherichia coli and Pichia pastoris are two of the most popular expression systems for producing isotope-enriched, recombinant protein samples for NMR investigations. The P. pastoris system can be used to produce (13)C, (15)N-enriched and even (2)H,(13)C, (15)N-enriched protein samples, but efficient methods for producing perdeuterated proteins with Ile (δ1), Leu and Val methyl-protonated groups in P. pastoris are still unavailable. Glycosylation heterogeneity also provides challenges to NMR studies. E. coli expression systems are efficient for overexpressing perdeuterated and Ile (δ1), Leu, Val methyl-protonated protein samples, but are generally not successful for producing secreted eukaryotic proteins with native disulfide bonds. The 33 kDa protein-Rhizopus chinensis lipase (RCL), an important industrial enzyme, was produced using both P. pastoris and E. coli BL21 trxB (DE3) systems. Samples produced from both systems exhibit identical native disulfide bond formation and similar 2D NMR spectra, indicating similar native protein folding. The yield of (13)C, (15)N-enriched r27RCL produced using P. pastoris was 1.7 times higher that obtained using E. coli, while the isotope-labeling efficiency was ~15 % lower. Protein samples produced in P. pastoris exhibit O-glycosylation, while the protein samples produced in E. coli were not glycosylated. The specific activity of r27RCL from P. pastoris was ~1.4 times higher than that produced in E. coli. These data demonstrate efficient production of (2)H, (13)C, (15)N

  1. Factors Controlling the Stable Nitrogen Isotopic Composition (δ15N of Lipids in Marine Animals.

    Directory of Open Access Journals (Sweden)

    Elisabeth Svensson

    Full Text Available Lipid extraction of biomass prior to stable isotope analysis is known to cause variable changes in the stable nitrogen isotopic composition (δ15N of residual biomass. However, the underlying factors causing these changes are not yet clear. Here we address this issue by comparing the δ15N of bulk and residual biomass of several marine animal tissues (fish, crab, cockle, oyster, and polychaete, as well as the δ15N of the extracted lipids. As observed previously, lipid extraction led to a variable offset in δ15N of biomass (differences ranging from -2.3 to +1.8 ‰. Importantly, the total lipid extract (TLE was highly depleted in 15N compared to bulk biomass, and also highly variable (differences ranging from -14 to +0.7 ‰. The TLE consisted mainly of phosphatidylcholines, a group of lipids with one nitrogen atom in the headgroup. To elucidate the cause for the 15N-depletion in the TLE, the δ15N of amino acids was determined, including serine because it is one of the main sources of nitrogen to N-containing lipids. Serine δ15N values differed by -7 to +2 ‰ from bulk biomass δ15N, and correlated well with the 15N depletion in TLEs. On average, serine was less depleted (-3‰ than the TLE (-7 ‰, possibly due to fractionation during biosynthesis of N-containing headgroups, or that other nitrogen-containing compounds, such as urea and choline, or recycled nitrogen contribute to the nitrogen isotopic composition of the TLE. The depletion in 15N of the TLE relative to biomass increased with the trophic level of the organisms.

  2. Reconstructing Century-Scale Changes in Nitrogen Cycling in Forests Throughout the United States using Tree-Ring δ15N Chronologies

    Science.gov (United States)

    Gerhart-Barley, L.; McLauchlan, K. K.; Battles, J. J.; Craine, J. M.; Higuera, P. E.; Mack, M. C.; McNeil, B. E.; Nelson, D. M.; Pederson, N.; Perakis, S. S.

    2016-12-01

    In recent decades, human perturbation of the global nitrogen (N) cycle has been immense with reactive nitrogen supply to ecosystems from anthropogenic sources now exceeding that of natural fixation. The impact of these perturbations on ecosystem nutrient cycling and plant communities is limited by the lack of long-term `baseline' assessments of N cycling prior to anthropogenic influences. Stable N isotope analysis (δ15N) of dendrochronological records have the potential to provide this baseline data, but to date have focused on short term, regional assessments. Here, we address this question with a data set incorporating 311 individual trees and 7,661 δ15N measurements from 50 sites throughout the contiguous United States. These sites represent the diversity of US forest types, climate conditions, N deposition, soil types, and disturbance histories. The chronologies span, on average, the last 162 calendar years, with the oldest chronology dating back to 1572 C.E. Consequently, this study is the first century- and continental-scale assessment of ecosystem N cycling using tree-ring chronologies. When aggregated, the chronologies show a consistent decline from 1825 C.E. to present, indicating declining N availability in US forests, despite global increases in N supply. Environmental factors such as mean annual precipitation (MAP), mean annual temperature (MAT), and mean annual nitrogen deposition (Ndep) did not contribute to average site δ15N values; however, MAP and MAT significantly affected temporal trajectories in tree-ring δ15N, with more negative slopes toward present occurring in regions with low MAT and high MAP. Quantity of atmospheric N deposition had no discernible impact on mean δ15N values or on the temporal slope. This lack of response is either because levels of N deposition are too low to produce a discernible response in any meaningful aspects of the N cycle, and/or the δ15N signature of depositional N is similar enough to ecosystem N pools that

  3. Alkaline Hydrolysis/Polymerization of 2,4,6-Trinitrotoluene: Characterization of Products by 13C and 15N NMR

    Science.gov (United States)

    Thorn, K.A.; Thorne, P.G.; Cox, L.G.

    2004-01-01

    Alkaline hydrolysis has been investigated as a nonbiological procedure for the destruction of 2,4,6-trinitrotoluene (TNT) in explosives contaminated soils and munitions scrap. Nucleophilic substitutions of the nitro and methyl groups of TNT by hydroxide ion are the initial steps in the alkaline degradation of TNT. Potential applications of the technique include both in situ surface liming and ex situ alkaline treatment of contaminated soils. A number of laboratory studies have reported the formation of an uncharacterized polymeric material upon prolonged treatment of TNT in base. As part of an overall assessment of alkaline hydrolysis as a remediation technique, and to gain a better understanding of the chemical reactions underlying the hydrolysis/polymerization process, the soluble and precipitate fractions of polymeric material produced from the calcium hydroxide hydrolysis of unlabeled and 15N-labeled TNT were analyzed by elemental analysis and 13C and 15N nuclear magnetic resonance spectroscopy. Spectra indicated that reactions leading to polymerization included nucleophilic displacement of nitro groups by hydroxide ion, formation of ketone, carboxyl, alcohol, ether, and other aliphatic carbons, conversion of methyl groups to diphenyl methylene carbons, and recondensation of aromatic amines and reduced forms of nitrite, including ammonia and possibly hydroxylamine, into the polymer. Compared to the distribution of carbons in TNT as 14% sp 3- and 86% sp2-hybridized, the precipitate fraction from hydrolysis of unlabeled TNT contained 33% sp3- and 67% sp 2-hybridized carbons. The concentration of nitrogen in the precipitate was 64% of that in TNT. The 15N NMR spectra showed that, in addition to residual nitro groups, forms of nitrogen present in the filtrate and precipitate fractions include aminohydroquinone, primary amide, indole, imine, and azoxy, among others. Unreacted nitrite was recovered in the filtrate fraction. The toxicities and susceptibilities to

  4. Alkaline hydrolysis/polymerization of 2,4,6-trinitrotoluene: characterization of products by 13C and 15N NMR.

    Science.gov (United States)

    Thorn, Kevin A; Thorne, Philip G; Cox, Larry G

    2004-04-01

    Alkaline hydrolysis has been investigated as a nonbiological procedure for the destruction of 2,4,6-trinitrotoluene (TNT) in explosives contaminated soils and munitions scrap. Nucleophilic substitutions of the nitro and methyl groups of TNT by hydroxide ion are the initial steps in the alkaline degradation of TNT. Potential applications of the technique include both in situ surface liming and ex situ alkaline treatment of contaminated soils. A number of laboratory studies have reported the formation of an uncharacterized polymeric material upon prolonged treatment of TNT in base. As part of an overall assessment of alkaline hydrolysis as a remediation technique, and to gain a better understanding of the chemical reactions underlying the hydrolysis/polymerization process, the soluble and precipitate fractions of polymeric material produced from the calcium hydroxide hydrolysis of unlabeled and 15N-labeled TNT were analyzed by elemental analysis and 13C and 15N nuclear magnetic resonance spectroscopy. Spectra indicated that reactions leading to polymerization included nucleophilic displacement of nitro groups by hydroxide ion, formation of ketone, carboxyl, alcohol, ether, and other aliphatic carbons, conversion of methyl groups to diphenyl methylene carbons, and recondensation of aromatic amines and reduced forms of nitrite, including ammonia and possibly hydroxylamine, into the polymer. Compared to the distribution of carbons in TNT as 14% sp3- and 86% sp2-hybridized, the precipitate fraction from hydrolysis of unlabeled TNT contained 33% sp3- and 67% sp2-hybridized carbons. The concentration of nitrogen in the precipitate was 64% of that in TNT. The 15N NMR spectra showed that, in addition to residual nitro groups, forms of nitrogen present in the filtrate and precipitate fractions include aminohydroquinone, primary amide, indole, imine, and azoxy, among others. Unreacted nitrite was recovered in the filtrate fraction. The toxicities and susceptibilities to

  5. Changes in soil nitrogen storage and δ15N with woody plant encroachment in a subtropical savanna parkland landscape

    Science.gov (United States)

    Boutton, T. W.; Liao, J. D.

    2010-09-01

    Subtropical woodlands dominated by N-fixing tree legumes have largely replaced grasslands in the Rio Grande Plains, southwestern United States, during the past century. To evaluate the impact of this vegetation change on the N cycle, we measured the mass and isotopic composition (δ15N) of N in the soil system of remnant grasslands and woody plant stands ranging in age from 10 to 130 years. Nitrogen accumulated at linear rates following woody encroachment in the litter (0.10-0.14 g N m-2 yr-1), roots (0.63-0.98 g N m-2 yr-1), and soils (0.75-3.50 g N m-2 yr-1), resulting in a 50%-150% increase in N storage in the soil system (0-30 cm) in woody stands older than 60 years. Simultaneous decreases in soil δ15N of up to 2‰ in the upper 30 cm of the profile are consistent with a scenario in which N inputs have exceeded losses following woody encroachment and suggest N accrual was derived from symbiotic N fixation by tree legumes and/or differential atmospheric N deposition to wooded areas. Vertical uplift and lateral transfer of N by the more deeply and intensively rooted woody plants may have contributed to N accumulation in wooded areas, but soil δ15N values are inconsistent with this explanation. N accumulation following woody encroachment may alter soil N availability, species interactions and successional dynamics, flux rates of key trace gases such as NOX and N2O and ecosystem C sequestration. Given the geographic dimensions of woody encroachment, these results may have implications for atmospheric composition and the climate system.

  6. Use of a 15N tracer to determine linkages between a mangrove and an upland freshwater swamp

    Science.gov (United States)

    MacKenzie, R. A.; Cormier, N.

    2005-05-01

    Mangrove forests and adjacent upland freshwater swamps are important components of subsistence-based economies of Pacific islands. Mangroves provide valuable firewood (Rhizophora apiculata) and mangrove crabs (Scylla serrata); intact freshwater swamps are often used for agroforestry (e.g., taro cultivation). While these two systems are connected hydrologically via groundwater and surface flows, little information is available on how they may be biogeochemically or ecologically linked. For example, mangrove leaf litter was once thought to be an important food source for resident and transient nekton and invertebrates, but this value may have been overestimated. Instead, nutrients or allochthonous material (e.g., phytoplankton, detritus) delivered via groundwater or surface water from upland freshwater swamps may play a larger role in mangrove food webs. Understanding the linkages between these two ecologically and culturally important ecosystems will help us to understand the potential impacts of hydrological alterations that occur when roads or bridges are constructed through them. We conducted a 15N tracer study in the Yela watershed on the island of Kosrae, Federated States of Micronesia. K15NO3 was continually added at trace levels for 4 weeks to the Yela River in an upland freshwater swamp adjacent to a mangrove forest. Nitrate and ammonium pools, major primary producers, macroinvertebrates, and fish were sampled from stations 5 m upstream (freshwater swamp) and 138, 188, 213, and 313 m downstream (mangrove) from the tracer addition. Samples were collected once a week prior to, during, and after the 15N addition for a total of 6 weeks. Preliminary results revealed no significant enrichment (mudskipper fish (Periophthalmus sp.). However, the 15N signature of ammonium pools was enriched 10-60 ‰ by the end of the third week. These results suggest that the tracer was present in the mangrove but was either unavailable to higher organisms or was incorporated into

  7. A New Approach to Determine the Total Airborne N Input into the Soil/Plant System Using 15N Isotope Dilution (ITNI: Results for Agricultural Areas in Central Germany

    Directory of Open Access Journals (Sweden)

    Rolf W.B. Russow

    2001-01-01

    Full Text Available The atmospheric deposition of nitrogen (N in the environment is of great concern due to its impact on natural ecosystems including affecting vegetation, reducing biodiversity, increasing tree growth in forests, and the eutrophication of aquatic systems. Taking into account the average annual N emission into the atmosphere in Germany of about 2 million t N (ammonia/ammonium, NOx, and assuming homogeneous distribution throughout Germany, an average N deposition of 45 kg/ha x year can be calculated. Such high atmospheric N deposition could be confirmed by N balances from long-term field experiments in Central Germany (e.g., the Static Fertilization Experiment in Bad Lauchstädt. By contrast, estimates by standard methods indicate a deposition of only about 30 kg N/ha x year. This is because the standard methods are using wet-only or bulk collectors, which fail to take into account gaseous deposition and the direct uptake of atmospheric N by aerial plant parts. Therefore, a new system was developed using 15N isotope dilution methodology to measure the actual total atmospheric N input into a soil/plant system (Integrated Total Nitrogen Input, ITNI. A soil/plant system is labeled with [15N]ammonium-[15N]nitrate and the total input of airborne N is calculated from the dilution of this tracer by N from the atmosphere. An average annual deposition of 64 ± 11 kg/ha x year from 1994–2000 was measured with the ITNI system at the Bad Lauchst?dt research farm in the dry belt of Central Germany. Measurements in 1999/2000 at three other sites in Central Germany produced deposition rates of about 60 kg/ha x year. These data clearly show that the total atmospheric N deposition into the soil/plant system determined by the newly developed ITNI system significantly exceeds that obtained from standard wet-only and bulk collectors. The higher atmospheric N depositions found closely match those postulated from the N balances of long-term agricultural field

  8. Millennium Ecosystem Assessment: MA Ecosystems

    Data.gov (United States)

    National Aeronautics and Space Administration — The Millennium Ecosystem Assessment: MA Ecosystems provides data and information on the extent and classification of ecosystems circa 2000, including coastal,...

  9. Tracing in situ amino acid uptake in plants and microbes with15N13C labelled compounds

    DEFF Research Database (Denmark)

    Andresen, Louise Christoffersen; Michelsen, Anders; Jonasson, Sven Evert

    amino acids. Furthermore, tannin addition tended to reduce plant uptake of label. By combining data on 15N recovery after 1 day in shoots and roots (fine and coarse) of the dominant heathland plants: the evergreen dwarf shrub Calluna vulgaris and the graminoid Deschampsia flexuosa, in soil...... microorganisms (chloroform fumigation extraction) and in soil water, we discuss the relative importance of free amino acids and ammonium as plant nutrients and microbial substrates in natural N-limited ecosystems with a high proportion of soil N held in tannin-N complexes. ...

  10. Acúmulo de nutrientes e destino do nitrogênio (15N aplicado em pomar jovem de laranjeira Nutrients accumulation and fate of nitrogen (15N in Young bearing orange trees

    Directory of Open Access Journals (Sweden)

    Rodrigo Marcelli Boaretto

    2007-01-01

    orchard, three plants were fertilized with 300 g per tree of N-[(15NH42SO 4] labeled with 15N to study the fate of N in the soil-orange tree system. Fruit yield and recovery of 15N by tree biomass were evaluated. The efficiency of fertilization, estimate by tree N absorption, varied from 20 to 27% of the total applied N. Fruits exported 35% of the N taken up from fertilizer. Furthermore, the highest fruit yield was attained with N rate of 400 g/tree.

  11. Food Labels

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Food Labels KidsHealth / For Teens / Food Labels What's in ... to have at least 95% organic ingredients. Making Food Labels Work for You The first step in ...

  12. Fossil Fuel Combustion-Related Emissions Dominate Atmospheric Ammonia Sources during Severe Haze Episodes: Evidence from 15N-Stable Isotope in Size-Resolved Aerosol Ammonium

    Science.gov (United States)

    Pan, Y.; Tian, S.; Liu, D.; Fang, Y.; Zhu, X.; Zhang, Q.; Zheng, B.; Michalski, G. M.; Wang, Y.

    2016-12-01

    The reduction of ammonia (NH3) emissions is urgently needed due to its major contributions to nitrogen deposition and particle pollution. However, the relative contributions of individual NH3 sources are unclear, and debate remains over whether agricultural emissions dominate atmospheric NH3 in urban areas. Based on the chemical and isotopic measurements of size-resolved aerosols in urban Beijing, China, we find that the natural abundance of 15N (expressed using δ15N values) of ammonium (NH4+) in fine particles varies with the development of haze episodes, ranging from -37.1‰ to -21.7‰ during clean/dusty days (relative humidity: ˜ 40%), to -13.1‰ to +5.8‰ during hazy days (relative humidity: 70-90%). After factoring the isotope exchange between NH3 gas and aerosol NH4+, the δ15N value of the initial NH3 during hazy days is found to be -14.5‰ to -1.6‰, which indicates fossil fuel-based emissions. These emissions contribute 90% of the total NH3 during hazy days in urban Beijing. This work demonstrates the analysis of δ15N values of aerosol NH4+ to be a promising new tool for partitioning atmospheric NH3 sources, providing policy makers with insights into NH3 emissions and secondary aerosols for regulation in urban environments. This work also shed lights on the sources of nitrogen deposition in downwind ecosystems.

  13. The influence of fish cage culture on δ{sup 13}C and δ{sup 15}N of filter-feeding Bivalvia (Mollusca)

    Energy Technology Data Exchange (ETDEWEB)

    Benedito, E.; Takeda, A.M., E-mail: eva@nupelia.uem.br [Universidade Estadual de Maringa (UEM), PR (Brazil). Nucleo de Pesquisas em Limnologia, Ictiologia e Aquicultura; Figueroa, L. [Universidade Estadual de Maringa (UEM), PR (Brazil). Pos-Graduacao em Ecologia de Ambientes Aquaticos Continentais; Manetta, GI. [Universidade Estadual de Maringa (UEM), PR (Brazil). Pos-Graduacao em Biologia Comparada

    2013-11-15

    The objective of this study was to evaluate the effect of Oreochromis niloticus cage culture promoted variations in the δ{sup 13}C and δ{sup 15}N in Corbicula fluminea (Mollusca; Bivalvia) and in the sediment of an aquatic food web. Samples were taken before and after net cage installation in the Rosana Reservoir (Paranapanema River, PR-SP). Samples of specimens of the bivalve filter C. fluminea and samples of sediment were collected using a modified Petersen grab. All samples were dried in an oven (60 °C) for 72 hours, macerated to obtain homogenous fine powders and sent for carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) isotopic value analysis in a mass spectrometer. There were significant differences in the δ{sup 13}C and δ{sup 15}N values of the invertebrate C. fluminea between the beginning and the end of the experiment. There were no differences between the δ{sup 13}C and δ{sup 15}N values of sediment. These results indicate that the installation of fish cage culture promoted impacts in the isotopic composition of the aquatic food web organisms, which could exert influence over the native species and the ecosystem. (author)

  14. Determination of 13C and 15N enrichments of urea in plasma by gas chromatography-combustion isotope ratio mass spectrometry and gas chromatography-mass spectrometry using the 2-methoxypyrimidine derivative

    NARCIS (Netherlands)

    Kulik, W.; Oosterveld, M. J. S.; Kok, R. M.; de Meer, K.

    2003-01-01

    We describe a GC-MS and GC-c-IRMS method for the determination of labeled urea tracer enrichments in plasma as a result of combined 13C- and 15N(2)-urea infusion experiments in piglets. Urea was converted into 2-methoxypyrimidine, a stable derivative, suited for analyses by both GC-MS and GC-c-IRMS.

  15. Effect of Carbonate Matrix on δ15N Analysis Tested for Simple Bulk Combustion on Coupled Elemental Analyzer-GC-IRMS

    Science.gov (United States)

    Saxena, D.; Grossman, E. L.; Maupin, C. R.; Roark, B.; O'Dea, A.

    2016-12-01

    Nitrogen isotopes (15N/14N) have been extensively used to reconstruct trophic structure, anthropogenic nutrient loading, ecosystem dynamics, and nutrient cycling in terrestrial and marine systems. Extending similar efforts to deep time is critical to investigate sources and fluxes of nutrients in past oceans, and explore causes of biotic turnover. To test the fidelity of N-isotope analyses of biogenic carbonate samples by simple bulk combustion, we performed two sets of experiments involving varying proportions of reagent CaCO3 (0, 2, 35 mg) and three organic standards (3.7-47.2 µg) viz. USGS40 (δ15NAir = -4.52‰), USGS41 (δ15NAir = +47.57‰), and in-house standard Rice (δ15NAir = +1.18‰). At high N contents (15-47.2 µg), δ15N values for CaCO3-amended samples are consistently either 0.5‰ higher (USGS40, -4.5‰), equivalent (Rice, 1.2‰), or 0.5‰ lower (USGS41, 47.6‰) relative to unamended samples. The difference thus depends on the δ15N of the standard relative to air. With decreasing N content (10-15 µg), δ15N values for CaCO3-amended samples diverge from expected values, with 35 mg CaCO3 samples diverging at the highest N content and 0 mg CaCO3 samples at the lowest (10 µg). The latter matches the lower sample-size limit for accurate measurement under the experimental conditions. At very low sample size (3.7-10 µg), all unamended standards show decreasing δ15N with decreasing N content, presumably because of non-linearity in instrument electronics and ion source behavior. The δ15N values of amended USGS41 also decrease with decreasing N content, but those of amended USGS40 and Rice samples increase, with samples containing more CaCO3 (35 versus 2 mg) showing greater deviation from expected values. Potential causes for deviation in δ15N values with CaCO3 amendments include N2 contamination from tin capsules and reagent CaCO3, and incomplete combustion due to energy consumption during CaCO3 decomposition. While tin capsules and reagent Ca

  16. Nitrogen source tracking with δ15N content of coastal wetland plants in Hawaii

    Science.gov (United States)

    Gregory L. Bruland; Richard A.. Mackenzie

    2010-01-01

    Inter- and intra-site comparisons of the nitrogen (N) stable isotope composition of wetland plant species have been used to identify sources of N in coastal areas. In this study, we compared δ15N values from different herbaceous wetland plants across 34 different coastal wetlands from the five main Hawaiian Islands and investigated relationships of δ15N with...

  17. Target-specific NMR detection of protein–ligand interactions with antibody-relayed {sup 15}N-group selective STD

    Energy Technology Data Exchange (ETDEWEB)

    Hetényi, Anasztázia [University of Szeged, Department of Medical Chemistry (Hungary); Hegedűs, Zsófia [University of Szeged, SZTE-MTA Lendület Foldamer Research Group, Institute of Pharmaceutical Analysis Department (Hungary); Fajka-Boja, Roberta; Monostori, Éva [Biological Research Center of the Hungarian Academy of Sciences, Lymphocyte Signal Transduction Laboratory, Institute of Genetics (Hungary); Kövér, Katalin E. [University of Debrecen, Department of Inorganic and Analytical Chemistry (Hungary); Martinek, Tamás A., E-mail: martinek@pharm.u-szeged.hu [University of Szeged, SZTE-MTA Lendület Foldamer Research Group, Institute of Pharmaceutical Analysis Department (Hungary)

    2016-12-15

    Fragment-based drug design has been successfully applied to challenging targets where the detection of the weak protein–ligand interactions is a key element. {sup 1}H saturation transfer difference (STD) NMR spectroscopy is a powerful technique for this work but it requires pure homogeneous proteins as targets. Monoclonal antibody (mAb)-relayed {sup 15}N-GS STD spectroscopy has been developed to resolve the problem of protein mixtures and impure proteins. A {sup 15}N-labelled target-specific mAb is selectively irradiated and the saturation is relayed through the target to the ligand. Tests on the anti-Gal-1 mAb/Gal-1/lactose system showed that the approach is experimentally feasible in a reasonable time frame. This method allows detection and identification of binding molecules directly from a protein mixture in a multicomponent system.

  18. Application of C30B15N15 heterofullerene in the isoniazid drug delivery: DFT studies

    Science.gov (United States)

    Hazrati, Mehrnoosh Khodam; Bagheri, Zargham; Bodaghi, Ali

    2017-05-01

    Using density functional theory, we have investigated the potential application of a C30B15N15 heterofullerene in anti-cancer isoniazid drug delivery. It was found that isoniazid prefers to attach via its -NH2 group to a boron atom of the C30B15N15 with releasing a large energy of about 21.91 kcal/mol. Our partial density of states analysis demonstrates that the boron atoms significantly contribute in generation of virtual orbitals of C30B15N15 fullerene, indicating that these atoms will be suitable for nucleophilic attack rather than carbon atoms. In addition to the large released energy, the electronic properties C30B15N15 are significantly sensitive to the isoniazid attachment which can recognize the drug trajectory by affecting the fluorescence emission properties. Unlike, different nanostructures whose structures need to be manipulated to be suitable for drug delivery, the C30B15N15 fullerene can be used in the pristine form. We proposed a drug release mechanism in cancer tissues, representing that in the low pH of the cancer cells the drug and C30B15N15 fullerene are considerably protonated, thereby separating the drug from the surface of the fullerene. The reaction mechanism of the drug with the fullerene is changed from covalence in natural environment to hydrogen bonding in acidic cancer cells.

  19. Highly 15N-Enriched Chondritic Clasts in the Isheyevo Meteorite

    Energy Technology Data Exchange (ETDEWEB)

    Bonal, L; Huss, G R; Krot, A N; Nagashima, K; Ishii, H A; Bradley, J P; Hutcheon, I D

    2009-01-14

    The metal-rich carbonaceous chondrites (CB and CH) have the highest whole-rock {sup 15}N enrichment ({delta}{sup 15}N up to +1500{per_thousand}), similar to {delta}{sup 15}N values reported in micron-sized regions (hotspots) of Interplanetary Dust Particles (IDPs) of possibly cometary origin and fine-grained matrices of unmetamorphosed chondrites. These {sup 15}N-rich hotspots are commonly attributed to low-temperature ion-molecule reactions in the protosolar molecular cloud or in the outer part of the protoplanetary disk. The nature of the whole-rock {sup 15}N enrichment of the metal-rich chondrites is not understood. We report a discovery of a unique type of primitive chondritic clasts in the CH/CB-like meteorite Isheyevo, which provides important constraints on the origin of {sup 15}N anomaly in metal-rich chondrites and nitrogen-isotope fractionation in the Solar System. These clasts contain tiny chondrules and refractory inclusions (5-15 {micro}m in size), and abundant ferromagnesian chondrule fragments (1-50 {micro}m in size) embedded in the partly hydrated, fine-grained matrix material composed of olivines, pyroxenes, poorly-organized aromatic organics, phyllosilicates and other hydrous phases. The mineralogy and oxygen isotope compositions of chondrules and refractory inclusions in the clasts are similar to those in the Isheyevo host, suggesting formation at similar heliocentric distances. In contrast to the previously known extraterrestrial samples, the fine-grained material in the clasts is highly and rather uniformly enriched in {sup 15}N, with bulk {delta}{sup 15}N values ranging between +1000 and +1300{per_thousand}; the {delta}{sup 15}N values in rare hotspots range from +1400 to +4000{per_thousand}. Since fine-grained matrices in the lithic clasts are the only component containing thermally unprocessed (during CAI and chondrule formation or during impact melting) materials that accreted into the metal rich chondrite parent body(ies), the {sup 15}N

  20. Intrapopulation variation in gray wolf isotope (delta(15)N and delta(13)C) profiles: implications for the ecology of individuals.

    Science.gov (United States)

    Urton, Erin J M; Hobson, Keith A

    2005-09-01

    Trophic relationships among organisms in terrestrial boreal ecosystems define ecological communities and are important in determining dynamics of energy flow and ecosystem function. We examined trophic relationships between the gray wolf (Canis lupus) and 18 mammalian species from the boreal forest of central Saskatchewan, Canada, using delta(13)C and delta(15)N stable isotope values measured in guard hair samples. Variance in isotope values for wolves and other carnivores was investigated as a proxy for variation in diet among individuals. Isosource, an isotopic source partitioning model, quantified the relative range in proportions of five most-likely prey items in the diets of wolves. The distribution of feasible contributions from each source was dominated by elk (Cervus elaphus; mean: 48%, range:11-75%), followed by white-tailed deer (Odocoileus virginianus; mean: 21%, range: 0-54%), moose (Alces alces; mean:14%, range: 0-41%), beaver (Castor canadensis; mean: 8%, range:0-25%) and snowshoe hare (Lepus americanus; mean: 8%, range: 0-24%). Despite social foraging, our results indicate highly variable diets among individuals and we discuss this in terms of individual versus group ecology of boreal wolves.

  1. Solution 1H, 15N NMR spectroscopic characterization of substrate-bound, cyanide-inhibited human heme oxygenase: water occupation of the distal cavity.

    Science.gov (United States)

    Li, Yiming; Syvitski, Ray T; Auclair, Karine; Ortiz de Montellano, Paul; La Mar, Gerd N

    2003-11-05

    A solution NMR spectroscopic study of the cyanide-inhibited, substrate-bound complex of uniformly (15)N-labeled human heme oxygenase, hHO, has led to characterization of the active site with respect to the nature and identity of strong hydrogen bonds and the occupation of ordered water molecules within both the hydrogen bonding network and an aromatic cluster on the distal side. [(1)H-(15)N]-HSQC spectra confirm the functionalities of several key donors in particularly robust H-bonds, and [(1)H-(15)N]HSQC-NOESY spectra lead to the identification of three additional robust H-bonds, as well as the detection of two more relatively strong H-bonds whose identities could not be established. The 3D NMR experiments provided only a modest, but important, extension of assignments because of the loss of key TOCSY cross-peaks due to the line broadening from a dynamic heterogeneity in the active site. Steady-state NOEs upon saturating the water signal locate nine ordered water molecules in the immediate vicinity of the H-bond donors, six of which are readily identified in the crystal structure. The additional three are positioned in available spaces to account for the observed NOEs. (15)N-filtered steady-state NOEs upon saturating the water resonances and (15)N-filtered NOESY spectra demonstrate significant negative NOEs between water molecules and the protons of five aromatic rings. Many of the NOEs can be rationalized by water molecules located in the crystal structure, but strong water NOEs, particularly to the rings of Phe47 and Trp96, demand the presence of at least an additional two immobilized water molecules near these rings. The H-bond network appears to function to order water molecules to provide stabilization for the hydroperoxy intermediate and to serve as a conduit to the active site for the nine protons required per HO turnover.

  2. The magnitude of spatial and temporal variation in δ15N and δ13C differs between taxonomic groups: Implications for food web studies

    Science.gov (United States)

    Hyndes, Glenn A.; Hanson, Christine E.; Vanderklift, Mathew A.

    2013-03-01

    Understanding variability in stable isotope abundance is essential for effective hypothesis testing and evaluating food sources, trophic levels and food web structure. The magnitude and sources of variability are likely to differ among taxonomic and functional groups. We aimed to quantify variability of δ13C and δ15N for 16 species representing seven distinct taxonomic groups of benthic invertebrates and autotrophs in a marine ecosystem. We quantified the magnitude of variability among individuals or shoots separated by metres, among eight sites separated by kilometres, and between two survey occasions separated by months. δ13C varied by as much as 7‰ for primary producers, 4‰ for consumers, while δ15N varied by as much as 9‰ and 2‰ respectively. Variation in δ15N of seagrass was largely accounted for by differences among sites, while variation in δ13C was mainly attributable to shoots collected a few metres apart. Compared to seagrasses, variation in macroalgae was mainly explained by differences between the two survey occasions for δ15N and among individuals collected a few metres apart for δ13C. Variation was generally lower for consumers and typically explained by differences among individuals for δ15N but displayed inconsistent patterns for δ13C. Dual isotope Bayesian mixing models showed that the potential contributions of food sources for herbivorous consumers varied among sites and between survey occasions, and also that there was high variability or uncertainty in the contributions of sources within sites. The relative consistency in the main sources of variation among broad taxonomic groups in autotrophs suggests that aspects of physiology that are phylogenetically conserved might be important influences on variation in natural abundances of stable isotopes. In comparison, the sources of variability were less consistent within and among broad consumer groups, suggesting complex interactions between consumers and their food sources.

  3. The dietary protein paradox and threonine 15 N-depletion: Pyridoxal-5'-phosphate enzyme activity as a mechanism for the δ15 N trophic level effect.

    Science.gov (United States)

    Fuller, Benjamin T; Petzke, Klaus J

    2017-04-30

    Nitrogen stable isotope ratios (δ15 N values) are used to reconstruct dietary patterns, but the biochemical mechanism(s) responsible for the diet to tissue trophic level effect and its variability are not fully understood. Here δ15 N amino acid (AA) values and physiological measurements (nitrogen intake, plasma albumin concentrations, liver-reduced glutathione concentrations and leucine oxidation rates) are used to investigate increased dietary protein consumption and oxidative stress (vitamin E deficiency) in rat total plasma protein. Using gas chromatography/combustion/isotope ratio mass spectrometry, the δ15 N values from N-pivaloyl-i-propyl esters of 15 AAs are reported for rats (n = 40) fed casein-based diets with: adequate protein (AP, 13.8%; n = 10), medium protein (MP, 25.7%; n = 10), high protein (HP, 51.3%; n = 10) or HP without vitamin E (HP-E; n = 10) for 18 weeks. Between the HP and AP groups, the δ15 NAA values of threonine (-4.0‰), serine (+1.4‰) and glycine (+1.2‰) display the largest differences and show significant correlations with: nitrogen intake, plasma albumin concentrations, liver-reduced glutathione concentrations and leucine oxidation rates. This indicates increased AA catabolism by the dietary induction of shared common metabolic pathways involving the enzymes threonine ammonia-lyase (EC 4.3.1.19), serine hydroxymethyltransferase (EC 2.1.2.1) and the glycine cleavage system (EC 2.1.2.10). The δ15 NAA values of the HP-E and HP groups were not found to be significantly different. The 15 N-depleted results of threonine are linked to increased activity of threonine ammonia-lyase, and show potential as a possible biomarker for protein intake and/or gluconeogenesis. We hypothesize that the inverse nitrogen equilibrium isotope effects of Schiff base formation, between AAs and pyridoxal-5'-phosphate cofactor enzymes, play a key role in the bioaccumulation and depletion of 15 N in the biomolecules of living organisms and

  4. Nitrogen Isotopic Ratios in Cometary NH2: Implication for 15N-fractionation in Ammonia

    Science.gov (United States)

    Shinnaka, Yoshiharu; Kawakita, Hideyo; Jehin, Emmanuël; Decock, Alice; Hutsemékers, Damien; Manfroid, Jean; Arai, Akira

    2015-11-01

    Isotopic ratios in cometary molecules are diagnostic for the physico-chemical conditions where molecules formed and are processed, from the interstellar medium to the solar nebula. Usually temperatures at the molecular formation control the fractionation of the heavier element in molecular species, e.g., D-fractionation in water.In cometary volatiles, the 14N/15N ratios in CN have been well observed (Manfroid et al. 2009, A&A, 503, 613, and reference therein) and is consistent with the ratio in HCN (a most probable parent of CN) measured in few comets (Bockelée-Morvan et al. 2008, ApJ, 679, L49). Those ratios are enriched compared to the proto-solar value by a factor of ~3. In contrast to those Nitriles, there are only few reports on 14N/15N ratios in Ammonia (as Amine) (Rousselot et al. 2014, ApJ, 780, L17; Shinnaka et al. 2014, ApJ, 782, L16). Ammonia (NH3) is usually the most abundant and HCN is the second most abundant N-bearing volatiles in cometary ice. Especially, recent observations of 15NH2 revealed the 14N/15N ratios in NH3 are comparable to those of CN. However, from the viewpoint of theoretical work, the enrichment of 15N in cometary NH3 cannot be reproduced by current chemical network models. Information about the diversity of the 14N/15N ratios in NH3 of individual comets is needed to understand the formation mechanisms/environments of NH3 in the early solar system.To clarify the diversity of the 14N/15N ratios in cometary NH3, we determine the 14N/15N ratios in NH3 for more than ten comets individually which include not only Oort cloud comets but also short period comets by using the high-resolution optical spectra of NH2. These spectra were obtained with both the UVES mounted on the VLT in Chile and the HDS on the Subaru Telescope in Hawaii.The derived 14N/15N ratios in NH3 for more than ten comets show high 15N-enrichment compared with the elemental abundances of nitrogen in the Sun by about factor of ~3 and has no large diversity depending on

  5. Oak loss increases foliar nitrogen, δ(15)N and growth rates of Betula lenta in a northern temperate deciduous forest.

    Science.gov (United States)

    Falxa-Raymond, Nancy; Patterson, Angelica E; Schuster, William S F; Griffin, Kevin L

    2012-09-01

    Oak forests dominate much of the eastern USA, but their future is uncertain due to a number of threats and widespread failure of oak regeneration. A sudden loss of oaks (Quercus spp.) could be accompanied by major changes in forest nitrogen (N) cycles with important implications for plant nutrient uptake and tree species composition. In this study, we measured the changes in N use and growth rates of black birch trees (Betula lenta L.) following oak girdling at the Black Rock Forest in southeastern New York, USA. Data were collected from nine experimental plots composed of three treatments: 100% oaks girdled (OG), 50% oaks girdled (O50) and control (C). Foliar N concentration and foliar (15)N abundance increased significantly in the oak-girdled plots relative to the control, indicating that the loss of oaks significantly altered N cycling dynamics. As mineralization and nitrification rates increase following oak loss, black birch trees increase N absorption as indicated by higher foliar N content and increased growth rates. Foliar N concentration increased by 15.5% in the O50 and 30.6% in the OG plots relative to the control, while O50 and OG plots were enriched in (15)N by 1.08‰ and 3.33‰, respectively (P < 0.0001). A 641% increase in black birch growth rates in OG plots suggests that this species is able to respond to additional N availability and/or increased light availability. The loss of oaks and subsequent increase in black birch productivity may have a lasting impact on ecosystem form and function.

  6. An Evolutionary Perspective on Global Vegetation \\delta15N Co-variance With Average Annual Precipitation

    Science.gov (United States)

    Sechrest, W.; Billmark, K. A.; Shields, L. G.; Swap, R. J.; Macko, S. A.

    2001-12-01

    Recent regional transect studies have shown a significant negative relationship between the \\delta15N value of vegetation and the mean annual precipitation. \\delta15N values provide an indication of the source nitrogen utilized by the plant owing to differential fractionations from biological and chemical processes. The fact that such a relationship exists across a variety of systems is surprising given the abundance of global plant species and the complexity of the nitrogen cycle. This observed pattern suggests that there may be some biological controls on plant utilization of nitrogen that are linked to available water. After observing this relationship in samples collected as a part of the Southern African Regional Science Initiative (SAFARI 2000), we have found that this relationship holds on a global scale for published values of \\delta15N. The critical question remains; is this relationship a result of shared characteristics of related species, or more broadly is there an evolutionary reason for this relationship? Since the \\delta15N values varied with rainfall, we hypothesize that the photosynthetic pathway utilized by plants play a role in this pattern. For example, plants that have evolved C4 metabolism, in other words, plants that have evolved mechanisms to allow for utilization of nutrients in a way more independent of available water than their C3 metabolizing counterparts, may exhibit different \\delta15N with respect to our original relationship. The data collected in conjunction with SAFARI 2000 confirms this hypothesis and as a result we have used modern phylogenetic techniques (using taxonomic information as a surrogate for true phylogenetic relationships between the included plant species) to test whether evolutionary history has played a role in the \\delta15N pattern. We anticipate that by using multidisciplinary tools this study will greatly advance ongoing research in the areas of nitrogen dynamics and vegetative biogeochemical cycling.

  7. Coral skeletal {delta}{sup 15}N reveals isotopic traces of an agricultural revolution

    Energy Technology Data Exchange (ETDEWEB)

    Marion, Guy S. [Department of Biological Sciences, Stanford University, Stanford, CA 94305 (United States)]. E-mail: g.marion@uq.edu.au; Dunbar, Robert B. [Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 (United States); Mucciarone, David A. [Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 (United States); Kremer, James N. [Department of Marine Sciences, University of Connecticut at Avery Point, Groton, CT 06340 (United States); Lansing, J. Stephen [Department of Anthropology, University of Arizona, Tucson, AZ 85721 (United States); Arthawiguna, Alit [Installation for Agricultural Research (IP 2TP), Kotak Pos 3480, Denpasar, Bali (Indonesia)

    2005-09-01

    This study introduces a new method of tracing the history of nutrient loading in coastal oceans via {delta}{sup 15}N analysis of organic nitrogen preserved in the skeleton of the massive Porites coral. Four coral cores were collected in Bali, Indonesia, from reefs exposed to high levels of fertilizers in agricultural run-off, from lagoonal corals impacted by sewage, and from a reef located 30 km offshore. Skeletal {delta}{sup 15}N in the agriculturally exposed coral declined from 10.7 {+-} 0.4 per mille in 1970-1971, when synthetic fertilizers (-0.8 per mille {+-} 0.2 per mille ) were introduced to Bali, to a depleted 'anthropogenic' baseline of 3.5 per mille {+-} 0.4% in the mid-1990s. {delta}{sup 15}N values were negatively correlated with rainfall, suggesting that marine {delta}{sup 15}N lowers during flood-born influxes of waste fertilizers. Reef cores exposed to untreated sewage in terrestrial discharge were enriched (7.8 and 7.3 {+-} 0.4 per mille ), while the offshore core reflected background oceanic signals (6.2 {+-} 0.4 per mille). {delta}{sup 15}N, N concentration, and C:N systematics indicate that the N isotopic composition of skeletal organic matter was generally well preserved over 30 years. We suggest that skeletal organic {delta}{sup 15}N can serve as a recorder of past nitrogen sources. In Bali, this tracer suggests that the intensification of Western style agricultural practices since 1970 are contributing to the degradation of coastal coral reefs.

  8. Organically treated biochar increases plant production and reduces N2O emissions: mechanistic insights by 15N tracing

    Science.gov (United States)

    Kammann, Claudia; Messerschmidt, Nicole; Clough, Tim; Schmidt, Hans-Peter; Marhan, Sven; Koyro, Hans-Werner; Steffens, Diedrich; Müller, Christoph

    2014-05-01

    Pyrogenic carbon (biochar) offers considerable potential for carbon capture and soil storage (CCSS) compared to other, less recalcitrant soil-C additives. Recent meta-analysis demonstrated that it can significantly reduce agricultural N2O emissions. Freshly produced biochars, however, do not always have yield-improving effects, i.e. there is no immediate economic incentive for using it. Hence, combining biochar with organic nutrient-rich amendments may be a promising agricultural strategy to accelerate CCSS, but it is unclear if biochar still reduces N2O emissions, in particular when it may act as nutrient carrier. We explored the potential of biochar to improve the GHG-cost/yield ratio and thereby its socio-economic value as soil amendment in two subsequent studies under controlled conditions: (1) A proof-of-concept study where the effects of untreated biochar were compared to those of co-composted biochar combined with stepwise improved nutritional regimes (+/- compost; +/- mineral-N application), and (2) a 15N-labeling-tracing study to unravel N exchange on biochar particles and N2O production and reduction mechanisms. Both studies were carried out in nutrient-poor sandy soils, the most likely initial target soils for biochar-CCSS strategies. While the untreated biochar reduced plant growth under N-limiting conditions, or at best did not reduce it, the co-composted biochar always significantly stimulated plant growth. The relative stimulation was largest with the lowest nutrient additions (305% versus 61% of control with untreated biochar). Electro-ultra-filtration analyses revealed that the co-composted but not the untreated biochar carried considerable amounts of easily extractable as well as more strongly sorbed plant nutrients, in particular nitrate and phosphorus. The subsequent 15N labelling-tracing study revealed that the co-composted biochar still (i) acted as a mineral-N exchange site for nitrate and ammonium despite its N-preloading, (ii) reduced N2O

  9. The role of electrostatic interactions and solvent polarity on the 15N NMR shielding of azines

    Science.gov (United States)

    Modesto-Costa, Lucas; Gester, Rodrigo M.; Manzoni, Vinícius

    2017-10-01

    The nitrogen-15 nuclear magnetic resonance (15N NMR) shielding of azines is very sensitive to the chemical environment. Theoretically, specific interactions are important on the calculation of their spectroscopic properties. However, the choice of the solvent model for the description of NMR shielding constants is still a subject of discussion. In this context, we analyse the role of electrostatic interactions on 15N NMR shielding as function of solvent polarity using the sequential-Quantum Mechanics/Molecular Mechanics approach methodology. Excellent agreement with experimental data of the NMR shielding was obtained without the inclusion of explicit solvent molecules either for polar or non polar solvents.

  10. 15N Fractionation in Star-Forming Regions and Solar System Objects

    Science.gov (United States)

    Wirstrom, Eva; Milam, Stefanie; Adande, GIlles; Charnley, Steven; Cordiner, Martin

    2015-01-01

    A central issue for understanding the formation and evolution of matter in the early Solar System is the relationship between the chemical composition of star-forming interstellar clouds and that of primitive Solar System materials. The pristinemolecular content of comets, interplanetary dust particles and carbonaceous chondrites show significant bulk nitrogen isotopic fractionation relative to the solar value, 14N15N 440. In addition, high spatial resolution measurements in primitive materials locally show even more extreme enhancements of 14N15N 100.

  11. Constraints on oceanic N balance/imbalance from sedimentary 15N records

    Directory of Open Access Journals (Sweden)

    M. A. Altabet

    2007-01-01

    Full Text Available According to current best estimates, the modern ocean's N cycle is in severe deficit. N isotope budgeting provides an independent geochemical constraint in this regard as well as the only means for past reconstruction. Overall, it is the relative proportion of N2 fixation consumed by water column denitrification that sets average oceanic δ15N under steady-state conditions. Several factors (conversion of organic N to N2, Rayleigh closed and open system effects likely reduce the effective fractionation factor (ε for water column denitrification to about half the inherent microbial value for εden. If so, the average oceanic δ15N of ~5‰ is consistent with a canonical contribution from water column denitrification of 50% of the source flux from N2 fixation. If an imbalance in oceanic N sources and sinks changes this proportion then a transient in average oceanic δ15N would occur. Using a simple model, changing water column denitrification by ±30% or N2 fixation by ±15% produces detectable (>1‰ changes in average oceanic δ15N over one residence time period or more with corresponding changes in oceanic N inventory. Changing sedimentary denitrification produces no change in δ15N but does change N inventory. Sediment δ15N records from sites thought to be sensitive to oceanic average δ15N all show no detectible change over the last 3 kyr or so implying a balanced marine N budget over the latest Holocene. A mismatch in time scales is the most likely meaningful interpretation of the apparent conflict with modern flux estimates. Decadal to centennial scale oscillations between net N deficit and net surplus may occur but on the N residence timescale of several thousand years, net balance is achieved in sum. However, sediment δ15N records from the literature covering the period since the last glacial maximum show excursions of up to several ‰ that are consistent with sustained N deficit during the deglaciation followed by readjustment

  12. Inoculation of Bacillus sphaericus UPMB-10 to Young Oil Palm and Measurement of Its Uptake of Fixed Nitrogen Using the 15N Isotope Dilution Technique

    Science.gov (United States)

    Zakry, Fitri Abdul Aziz; Shamsuddin, Zulkifli H.; Rahim, Khairuddin Abdul; Zakaria, Zin Zawawi; Rahim, Anuar Abdul

    2012-01-01

    There are increasing applications of diazotrophic rhizobacteria in the sustainable agriculture system. A field experiment on young immature oil palm was conducted to quantify the uptake of N derived from N2 fixation by the diazotroph Bacillus sphaericus strain UPMB-10, using the 15N isotope dilution method. Eight months after 15N application, young immature oil palms that received 67% of standard N fertilizer application together with B. sphaericus inoculation had significantly lower 15N enrichment than uninoculated palms that received similar N fertilizers. The dilution of labeled N served as a marker for the occurrence of biological N2 fixation. The proportion of N uptake that was derived from the atmosphere was estimated as 63% on the whole plant basis. The inoculation process increased the N and dry matter yields of the palm leaflets and rachis significantly. Field planting of young, immature oil palm in soil inoculated with B. sphaericus UPMB-10 might mitigate inorganic fertilizer-N application through supplementation by biological nitrogen fixation. This could be a new and important source of nitrogen biofertilizer in the early phase of oil palm cultivation in the field. PMID:22446306

  13. Ecosystem services

    Science.gov (United States)

    Trista Patterson

    2014-01-01

    Since its inception, the ecosystem service approach has stimulated interest from numerous planning, management, and partnership perspectives. To date, however, research that quantifies ecosystem services in the study area (in the form of explicit ecosystem service studies) has been limited. This chapter reviews and synthesizes the concept of ecosystem services,...

  14. Can δ15N and δ13C stable isotopes and fatty acid signatures ...

    African Journals Online (AJOL)

    Temporal changes in fatty acid composition and δ15N, δ13C stable isotope values of the phytobenthos growing on artificial clay substrates under natural conditions over a 28-day period at an upstream and a downstream site in the Kowie River near Grahamstown were investigated in 2012. High concentrations of diatom ...

  15. Measurement of marine productivity using 15 N and 13 C tracers ...

    Indian Academy of Sciences (India)

    Difference in energy requirement for assimilation of different nitrogen compounds decides the preferred nitrogen source during the early hours of incubation. Variation in light intensity during incubation also plays a significant role in the assimilation of nitrogen. Results from time course experiments with both 15N and 13C ...

  16. 948 15 N as a tool to demonstrate the contribution of fish-waste ...

    African Journals Online (AJOL)

    This study uses stable isotope ratios of nitrogen (ä15N) to test the hypothesis that a bloom of the green seaweed Ulva lactuca, which occurred in Saldanha Bay, South Africa, in summer 1993/94 was linked to an adjacent discharge of nitrogen from pelagic fish processing waste. It is suggested that only two significant ...

  17. Determination of level widths in 15N using nuclear resonance fluorescence

    Directory of Open Access Journals (Sweden)

    Szücs T.

    2015-01-01

    Full Text Available Level widths in 15N have been measured with the nuclear resonance fluorescence (NRF technique. Solid nitrogen compounds, bremsstrahlung, and HPGe detectors have been used as target, beam, and detectors, respectively. The preliminarily level widths are in agreement with the literature values, but more precise.

  18. Monitoring the refinement of crystal structures with (15)N solid-state NMR shift tensor data.

    Science.gov (United States)

    Kalakewich, Keyton; Iuliucci, Robbie; Mueller, Karl T; Eloranta, Harriet; Harper, James K

    2015-11-21

    The (15)N chemical shift tensor is shown to be extremely sensitive to lattice structure and a powerful metric for monitoring density functional theory refinements of crystal structures. These refinements include lattice effects and are applied here to five crystal structures. All structures improve based on a better agreement between experimental and calculated (15)N tensors, with an average improvement of 47.0 ppm. Structural improvement is further indicated by a decrease in forces on the atoms by 2-3 orders of magnitude and a greater similarity in atom positions to neutron diffraction structures. These refinements change bond lengths by more than the diffraction errors including adjustments to X-Y and X-H bonds (X, Y = C, N, and O) of 0.028 ± 0.002 Å and 0.144 ± 0.036 Å, respectively. The acquisition of (15)N tensors at natural abundance is challenging and this limitation is overcome by improved (1)H decoupling in the FIREMAT method. This decoupling dramatically narrows linewidths, improves signal-to-noise by up to 317%, and significantly improves the accuracy of measured tensors. A total of 39 tensors are measured with shifts distributed over a range of more than 400 ppm. Overall, experimental (15)N tensors are at least 5 times more sensitive to crystal structure than (13)C tensors due to nitrogen's greater polarizability and larger range of chemical shifts.

  19. δ15N in sedimenting particles as indicator of euphotic-zone processes

    Science.gov (United States)

    Voss, M.; Altabet, M. A.; Bodungen, B. v.

    1996-01-01

    Stable nitrogen isotopes ( δ15N) were analyzed in sedimenting particles in the northern North Atlantic at the Vöring Plateau at 500 m depth and in the Lofoten Basin at 500, 1000 and 3000 m depth over a period of up to 3 years. Suspended particles were sampled throughout the entire water column in early summer, autumn and winter in the Lofoten Basin only. From this data set a seasonal cycle of δ15N-PON (particulate organic nitrogen) was constructed and supplemented by calculations of δ15N-PON from nitrate data (after Rayleigh fractionation formulae). Sediment trap δ15N-PON values from 500 m showed a clear seasonal signal with a 7‰ drop from winter to spring and a similar increase again in winter. This seasonal pattern in δ15N of sedimenting particles also occurred in trap collections at 3000 m depth with a delay of approximately two months. It is assumed that fractionation during nitrate uptake in spring and early summer and increased sedimentation of isotopically light phytodetritus are the main reasons for this pronounced seasonal pattern. Surface water degradation processes, uptake of isotopically heavy nitrate, and heterotrophic activity cause the increase in δ15N-PON in sinking matter towards autumn. In winter the nitrogen isotope values remain isotopically heavy. The observed seasonal pattern and quantity of sinking fluxes compared well with the calculations. Surprisingly, the suspended particle pool below the winter mixed layer also had a seasonal signal, with a 5‰ increase in δ15N between June and September and a decrease towards November. In the absence of intense biological fractionation the sinking and suspended particle pools obviously undergo considerable exchange of material, which seems to be more intense during spring and less during autumn and winter. The nitrogen isotope signal in the particulate material in the deep northern North Atlantic is clearly dominated by the fractionation of the limiting nitrate pool, causing a much higher

  20. Dry season limnological conditions and basin geology exhibit complex relationships with δ13C and δ15N of carbon sources in four Neotropical floodplains

    Science.gov (United States)

    Hoeinghaus, David J.; Manetta, Gislaine I.; Benedito, Evanilde

    2017-01-01

    Studies in freshwater ecosystems are seeking to improve understanding of carbon flow in food webs and stable isotopes have been influential in this work. However, variation in isotopic values of basal production sources could either be an asset or a hindrance depending on study objectives. We assessed the potential for basin geology and local limnological conditions to predict stable carbon and nitrogen isotope values of six carbon sources at multiple locations in four Neotropical floodplain ecosystems (Paraná, Pantanal, Araguaia, and Amazon). Limnological conditions exhibited greater variation within than among systems. δ15N differed among basins for most carbon sources, but δ13C did not (though high within-basin variability for periphyton, phytoplankton and particulate organic carbon was observed). Although δ13C and δ15N values exhibited significant correlations with some limnological factors within and among basins, those relationships differed among carbon sources. Regression trees for both carbon and nitrogen isotopes for all sources depicted complex and in some cases nested relationships, and only very limited similarity was observed among trees for different carbon sources. Although limnological conditions predicted variation in isotope values of carbon sources, we suggest the resulting models were too complex to enable mathematical corrections of source isotope values among sites based on these parameters. The importance of local conditions in determining variation in source isotope values suggest that isotopes may be useful for examining habitat use, dispersal and patch dynamics within heterogeneous floodplain ecosystems, but spatial variability in isotope values needs to be explicitly considered when testing ecosystem models of carbon flow in these systems. PMID:28358822

  1. Dry season limnological conditions and basin geology exhibit complex relationships with δ13C and δ15N of carbon sources in four Neotropical floodplains.

    Science.gov (United States)

    Zaia Alves, Gustavo H; Hoeinghaus, David J; Manetta, Gislaine I; Benedito, Evanilde

    2017-01-01

    Studies in freshwater ecosystems are seeking to improve understanding of carbon flow in food webs and stable isotopes have been influential in this work. However, variation in isotopic values of basal production sources could either be an asset or a hindrance depending on study objectives. We assessed the potential for basin geology and local limnological conditions to predict stable carbon and nitrogen isotope values of six carbon sources at multiple locations in four Neotropical floodplain ecosystems (Paraná, Pantanal, Araguaia, and Amazon). Limnological conditions exhibited greater variation within than among systems. δ15N differed among basins for most carbon sources, but δ13C did not (though high within-basin variability for periphyton, phytoplankton and particulate organic carbon was observed). Although δ13C and δ15N values exhibited significant correlations with some limnological factors within and among basins, those relationships differed among carbon sources. Regression trees for both carbon and nitrogen isotopes for all sources depicted complex and in some cases nested relationships, and only very limited similarity was observed among trees for different carbon sources. Although limnological conditions predicted variation in isotope values of carbon sources, we suggest the resulting models were too complex to enable mathematical corrections of source isotope values among sites based on these parameters. The importance of local conditions in determining variation in source isotope values suggest that isotopes may be useful for examining habitat use, dispersal and patch dynamics within heterogeneous floodplain ecosystems, but spatial variability in isotope values needs to be explicitly considered when testing ecosystem models of carbon flow in these systems.

  2. (15)N and (1)H Solid-State NMR Investigation of a Canonical Low-Barrier Hydrogen-Bond Compound: 1,8-Bis(dimethylamino)naphthalene.

    Science.gov (United States)

    White, Paul B; Hong, Mei

    2015-09-03

    Strong or low-barrier hydrogen bonds have often been proposed in proteins to explain enzyme catalysis and proton-transfer reactions. So far (1)H chemical shifts and scalar couplings have been used as the main NMR spectroscopic signatures for strong H-bonds. In this work, we report simultaneous measurements of (15)N and (1)H chemical shifts and N-H bond lengths by solid-state NMR in (15)N-labeled 1,8-bis(dimethylamino)naphthalene (DMAN), which contains a well-known strong NHN H-bond. We complexed DMAN with three different counteranions to examine the effects of the chemical environment on the H-bond lengths and chemical shifts. All three DMAN compounds exhibit significantly elongated N-H distances compared to the covalent bond length, and the (1)H(N) chemical shifts are larger than ∼17 ppm, consistent with strong NHN H-bonds in the DMAN cation. However, the (15)N and (1)H chemical shifts and the precise N-H distances differ among the three compounds, and the (15)N chemical shifts show opposite dependences on the proton localization from the general trend in organic compounds, indicating the significant effects of the counteranions on the electronic structure of the H-bond. These data provide useful NMR benchmarks for strong H-bonds and caution against the sole reliance on chemical shifts for identifying strong H-bonds in proteins since neighboring side chains can exert influences on chemical shifts similar to those of the bulky organic anions in DMAN. Instead, N-H bond lengths should be measured, in conjunction with chemical shifts, as a more fundamental parameter of H-bond strength.

  3. {sup 1}H and {sup 15}N resonance assignment, secondary structure and dynamic behaviour of the C-terminal domain of human papillomavirus oncoprotein E6

    Energy Technology Data Exchange (ETDEWEB)

    Nomine, Yves; Charbonnier, Sebastian [Laboratoire d' Immunotechnologie, CNRS UMR 7100, Ecole Superieure de Biotechnologie de Strasbourg (France); Miguet, Laurent; Potier, Noelle; Dorsselaer, Alain Van [Laboratoire de Spectrometrie de Masse Bio-Organique, CNRS UMR 7509, Faculte de Chimie (France); Atkinson, R. Andrew [Laboratoire de RMN, CNRS UMR 7104, Ecole Superieure de Biotechnologie de Strasbourg (France); Trave, Gilles [Laboratoire d' Immunotechnologie, CNRS UMR 7100, Ecole Superieure de Biotechnologie de Strasbourg (France)], E-mail: trave@esbs.u-strasbg.fr; Kieffer, Bruno [Laboratoire de RMN, CNRS UMR 7104, Ecole Superieure de Biotechnologie de Strasbourg (France)], E-mail: kieffer@esbs.u-strasbg.fr

    2005-02-15

    E6 is a viral oncoprotein implicated in cervical cancers, produced by human papillomaviruses (HPVs). E6 contains two putative zinc-binding domains of about 75 residues each. The difficulty in producing recombinant E6 has long hindered the obtention of structural data. Recently, we described the expression and purification of E6-C 4C/4S, a stable, folded mutant of the C-terminal domain of HPV16 E6. Here, we have produced {sup 15}N-labelled samples of E6-C 4C/4S for structural studies by NMR. We have assigned most {sup 1}H and {sup 15}N resonances and identified the elements of secondary structure of the domain. The domain displays an original {alpha}/{beta} topology with roughly equal proportions of {alpha}-helix and {beta}-sheet. The PDZ-binding region of E6, located at the extreme C-terminus of the domain, is in a random conformation. Mass spectrometry demonstrated the presence of one zinc ion per protein molecule. Kinetics of replacement of zinc by cadmium followed by {sup 1}H,{sup 15}N-HSQC experiments revealed specific frequency changes for the zinc-binding cysteines and their immediate neighbours. NMR spectra were affected by severe line-broadening effects which seriously hindered the assignment work. Investigation of these effects by {sup 15}N relaxation experiments showed that they are due to heterogeneous dynamic behaviour with {mu}s-ms time scale motions occurring in localised regions of the monomeric domain.

  4. Interception of residual nitrate from a calcareous alluvial soil profile on the North China Plain by deep-rooted crops: A {sup 15}N tracer study

    Energy Technology Data Exchange (ETDEWEB)

    Ju, X.T. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, 2 Yuan Ming Yuan West Road, Hai Dian District, Beijing 100094 (China)]. E-mail: juxt@cau.edu.cn; Gao, Q. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, 2 Yuan Ming Yuan West Road, Hai Dian District, Beijing 100094 (China); College of Agricultural Resources and Environmental Sciences, Jilin Agricultural University, Changchun 130118 (China); Christie, P. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, 2 Yuan Ming Yuan West Road, Hai Dian District, Beijing 100094 (China); Agricultural and Environmental Science Department, Queen' s University Belfast, Belfast BT9 5PX (United Kingdom); Zhang, F.S. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, 2 Yuan Ming Yuan West Road, Hai Dian District, Beijing 100094 (China)

    2007-03-15

    {sup 15}N-labeled nitrate was injected into different depths of an alluvial calcareous soil profile on the North China Plain. Subsequent movement of NO{sub 3} {sup -}N and its recovery by deep-rooted maize (Zea mays L.) and shallow-rooted eggplant (Solanum melongena L.) were studied. Under conventional water and nutrient management the mean recoveries of {sup 15}N-labeled nitrate from K{sup 15}NO{sub 3} injected at depths 15, 45, and 75 cm were 22.4, 13.8, and 7.8% by maize and 7.9, 4.9, and 2.7% by eggplant. The recovery rate by maize at each soil depth was significantly higher than by eggplant. The deeper the injection of nitrate the smaller the distance of its downward movement and this corresponded with the movement of soil water during crop growth. Deeper rooting crops with high root length density and high water consumption may therefore be grown to utilize high concentrations of residual nitrate in the subsoil from previous intensive cropping and to protect the environment. - Deep-rooted crops have a greater capacity than shallow-rooted crops to intercept residual nitrate from the subsoil and restrict its movement down to the shallow groundw0010at.

  5. Tracking the fate of nitrate through pulse-flow wetlands: A mesocosm scale 15N enrichment tracer study

    Science.gov (United States)

    Messer, Tiffany L.; Burchell, Michael R.; Böhlke, John Karl; Tobias, Craig R.

    2017-01-01

    Quantitative information about the fate of applied nitrate (NO3-N) in pulse-flow constructed wetlands is essential for designing wetland treatment systems and assessing their nitrogen removal services for agricultural and stormwater applications. Although many studies have documented NO3-N losses in wetlands, controlled experiments indicating the relative importance of different processes and N sinks are scarce. In the current study, 15NO3-N isotope enrichment tracer experiments were conducted in wetland mesocosms of two different wetland soil types at two realistic agricultural NO3-N source loads. The 15N label was traced from the source NO3-N into plant biomass, soil (including organic matter and ammonium), and N-gas constituents over 7–10 day study periods. All sinks responded positively to higher NO3-N loading. Plant uptake exceeded denitrification 2–3 fold in the low NO3-N loading experiments, while both fates were nearly equivalent in the high loading experiments. One to two years later, soils largely retained the assimilated tracer N, whereas plants had lost much of it. Results demonstrated that plant and microbial assimilation in the soil (temporary N sinks) can exceed denitrification (permanent N loss) in pulse-flow environments and must be considered by wetland designers and managers for optimizing nitrogen removal potential.

  6. The Five-Year Fate of a 15N Tracer in a Mixed Deciduous Forest: Retention, Redistribution, and Differences by Mycorrhizal Association

    Science.gov (United States)

    Goodale, C. L.

    2015-12-01

    The impact of nitrogen deposition on forest ecosystems depends in large part on its fate: uptake by trees can stimulate growth, while gaseous or leaching losses contribute to air and water pollution and represent the loss of a limiting nutrient. Past tracer studies have shown that soils dominate the short-term fate of added 15N, but its longer-term term fate remains uncertain. This study examined how much 15N tracer moved plant or soil pools or was lost over 5-6 years. In 2007, a 15N tracer (0.21 kg/ha as 99% enriched 15N-KNO3) was added to 0.25 ha mixed hardwood forest in central NY. All of the tracer was recovered in the days after its addition, but recovery fell to 78% by the end of this year (25% surface litter, 48% 0-10 cm soil, 5% roots). One year later, recovery in these pools fell (to 51%), with losses from surface litter (-11%) and the 0-10 cm soils (-15%), including losses from the "heavy" soil fraction. Additional tracer moved to other plant pools (+5%) and to deeper soil (+13%; up to 30 cm), for a total recovery of 69% of the added tracer. Between years 1 and 5-6, only total tracer recovery decreased by only 1.4%. Recovery decreased in foliage (-0.2%), all roots (-3.5%), and surface litter (-9.8%), while increasing in woody biomass (+0.9%), 0-10 cm soil (+8.9%), and deep soil (+2.3%; up to 50 cm). Tracer recovery in live and dead plant N pools (11%) did not change, as 3% moved from roots into aboveground plant tissues and 3% moved from live plant pools into leaf litter; these results imply no net transfer of 15N from soil to plants during this period. Over all 5-6 years, only 1.6% of the tracer moved into bark or wood, a small but important sink because of its high C:N ratio; however, roughly one-third of this total was in wood formed prior to the start of the tracer addition. Tree species differed in their recovery of 15N: the six species with ectomycorrhizal associations showed more enrichment than the four species with arbuscular mycorrhizae. It is

  7. Leaf δ15N as an indicator of arbuscular mycorrhizal nitrogen uptake in a coastal-plain forest (restinga forest) at Southeastern Brazil

    Science.gov (United States)

    Mardegan, S. F.; Valadares, R.; Martinelli, L.

    2013-12-01

    Restinga diversity contrasts with a series of adverse environmental conditions that constrain their development, including nutrient limitation. In this sense, the mutualistic symbiosis between plants and arbuscular mycorrhizal fungi (AMF) may contribute in nutrient acquisition, including nitrogen. However, this association deeply affects plant nitrogen isotopic composition (δ15N), since assimilation processes and biochemical reactions within the fungi may reflect in a delivered product with an isotopic composition about 8 to 10 ‰ lower than that observed at the fungal symbiont per se. Here we assessed if the association with AMF affects δ15N values of plant species from a coastal-plain forest (restinga forest) at Southeastern Brazil. Accordingly, we analyzed the nutritional and isotopic compositions from ecosystem key-compartments (soil, litter and leaves), relating plant δ15N with the colonization rates. The study was carried out in a permanent plot (1 ha) at a coastal-plain forest (restinga forest) at the Serra do Mar State Park, SP, Brazil. Sampled vegetation is characterized by the lack of a well-defined stratification and a rather open canopy. It also comprises trees ranging from 10 to 15-m high. Soils are deep and sandy, being characterized by high acidity, nutrient deficiency and a dense litter cover. We randomly collected five samples (250 mg) from topsoil (0-10 cm) and five to ten leaves from individuals belonging to 16 plant species of high relevance within the site (IVI index). We also collected superficial (0-10 cm depth) fine roots (5 g) and 13 samples (100 g) of fine litter next to the individuals sampled. Soil samples were air-dried, sieved, homogenized and used in the physical-chemical characterization. The remainder was ground to a fine powder to determine nitrogen concentrations and δ15N values. Leaves were dried at 50 °C, finely milled and used for the determination of nitrogen concentrations, C/N ratios and δ15N values. Root samples were

  8. Variable δ15N Diet-Tissue Discrimination Factors among Sharks: Implications for Trophic Position, Diet and Food Web Models

    Science.gov (United States)

    Olin, Jill A.; Hussey, Nigel E.; Grgicak-Mannion, Alice; Fritts, Mark W.; Wintner, Sabine P.; Fisk, Aaron T.

    2013-01-01

    The application of stable isotopes to characterize the complexities of a species foraging behavior and trophic relationships is dependent on assumptions of δ15N diet-tissue discrimination factors (∆15N). As ∆15N values have been experimentally shown to vary amongst consumers, tissues and diet composition, resolving appropriate species-specific ∆15N values can be complex. Given the logistical and ethical challenges of controlled feeding experiments for determining ∆15N values for large and/or endangered species, our objective was to conduct an assessment of a range of reported ∆15N values that can hypothetically serve as surrogates for describing the predator-prey relationships of four shark species that feed on prey from different trophic levels (i.e., different mean δ15N dietary values). Overall, the most suitable species-specific ∆15N values decreased with increasing dietary-δ15N values based on stable isotope Bayesian ellipse overlap estimates of shark and the principal prey functional groups contributing to the diet determined from stomach content analyses. Thus, a single ∆15N value was not supported for this speciose group of marine predatory fishes. For example, the ∆15N value of 3.7‰ provided the highest percent overlap between prey and predator isotope ellipses for the bonnethead shark (mean diet δ15N = 9‰) whereas a ∆15N value shark (mean diet δ15N = 15‰). These data corroborate the previously reported inverse ∆15N-dietary δ15N relationship when both isotope ellipses of principal prey functional groups and the broader identified diet of each species were considered supporting the adoption of different ∆15N values that reflect the predators’ δ15N-dietary value. These findings are critical for refining the application of stable isotope modeling approaches as inferences regarding a species’ ecological role in their community will be influenced with consequences for conservation and management actions. PMID:24147026

  9. Variable δ(15N diet-tissue discrimination factors among sharks: implications for trophic position, diet and food web models.

    Directory of Open Access Journals (Sweden)

    Jill A Olin

    Full Text Available The application of stable isotopes to characterize the complexities of a species foraging behavior and trophic relationships is dependent on assumptions of δ(15N diet-tissue discrimination factors (∆(15N. As ∆(15N values have been experimentally shown to vary amongst consumers, tissues and diet composition, resolving appropriate species-specific ∆(15N values can be complex. Given the logistical and ethical challenges of controlled feeding experiments for determining ∆(15N values for large and/or endangered species, our objective was to conduct an assessment of a range of reported ∆(15N values that can hypothetically serve as surrogates for describing the predator-prey relationships of four shark species that feed on prey from different trophic levels (i.e., different mean δ(15N dietary values. Overall, the most suitable species-specific ∆(15N values decreased with increasing dietary-δ(15N values based on stable isotope Bayesian ellipse overlap estimates of shark and the principal prey functional groups contributing to the diet determined from stomach content analyses. Thus, a single ∆(15N value was not supported for this speciose group of marine predatory fishes. For example, the ∆(15N value of 3.7‰ provided the highest percent overlap between prey and predator isotope ellipses for the bonnethead shark (mean diet δ(15N = 9‰ whereas a ∆(15N value < 2.3‰ provided the highest percent overlap between prey and predator isotope ellipses for the white shark (mean diet δ(15N = 15‰. These data corroborate the previously reported inverse ∆(15N-dietary δ(15N relationship when both isotope ellipses of principal prey functional groups and the broader identified diet of each species were considered supporting the adoption of different ∆(15N values that reflect the predators' δ(15N-dietary value. These findings are critical for refining the application of stable isotope modeling approaches as inferences regarding a species

  10. Does labelling frequency affect N rhizodeposition assessment using the cotton-wick method?

    DEFF Research Database (Denmark)

    Mahieu, S.; Fustec, J.; Jensen, Erik Steen

    2009-01-01

    The aim of the present study was to test and improve the reliability of the 15N cotton-wick method for measuring soil N derived from plant rhizodeposition, a critical value for assessing belowground nitrogen input in field-grown legumes. The effects of the concentration of the 15N labelling...

  11. Nutrition Labeling

    DEFF Research Database (Denmark)

    Grunert, Klaus G

    2013-01-01

    because consumers will avoid products that the label shows to be nutritionally deficient, but also because food producers will try to avoid marketing products that appear, according to the label, as nutritionally problematic, for example, because of a high content of saturated fat or salt. Nutrition......Nutrition labeling refers to the provision of information on a food product’s nutritional content on the package label. It can serve both public health and commercial purposes. From a public health perspective, the aim of nutrition labeling is to provide information that can enable consumers...... to make healthier choices when choosing food products. Nutrition labeling is thus closely linked to the notion of the informed consumer, that chooses products according to their aims, on the basis of the information at their disposal. Because many consumers are assumed to be interested in making healthy...

  12. Nutrition Labeling

    Science.gov (United States)

    Metzger, Lloyd E.

    Nutrition labeling regulations differ in countries around the world. The focus of this chapter is on nutrition labeling regulations in the USA, as specified by the Food and Drug Administration (FDA) and the Food Safety and Inspection Service (FSIS) of the United States Department of Agriculture (USDA). A major reason for analyzing the chemical components of foods in the USA is nutrition labeling regulations. Nutrition label information is not only legally required in many countries, but also is of increasing importance to consumers as they focus more on health and wellness.

  13. Inside Ecosystems.

    Science.gov (United States)

    Moll, Gary; And Others

    1995-01-01

    The third in a series of articles featuring the urban ecosystem. Discusses the inner workings of an ecosystem and the links that connect its elements, including the link between people and the environment. Graphics illustrate "layers" of the landscape. (LZ)

  14. The Styrene Probe Applied to 15N and 77Se NMR

    Science.gov (United States)

    1988-08-01

    Specific quantitative correlation equations have been developed for the following N-containing compounds: anilines, benzenesulfonamides, acetanilides ...LVII 45 46 The azlactones were also much less soluble than the other compound series in the NMR solvents used (CD 3NO 2 and CDCI3), reducing the...spite of the much lower solubility of these compounds versus the other series. A typical parameter menu for these runs follows: 77 Table 9 15N Standard

  15. Density functional calculations of {sup 15}N chemical shifts in solvated dipeptides

    Energy Technology Data Exchange (ETDEWEB)

    Cai Ling; Fushman, David, E-mail: fushman@umd.edu; Kosov, Daniel S. [University of Maryland, Department of Chemistry and Biochemistry (United States)], E-mail: dkosov@umd.edu

    2008-06-15

    We performed density functional calculations to examine the effects of solvation, hydrogen bonding, backbone conformation, and the side chain on {sup 15}N chemical shielding in proteins. We used N-methylacetamide (NMA) and N-formyl-alanyl-X (with X being one of the 19 naturally occurring amino acids excluding proline) as model systems. In addition, calculations were performed for selected fragments from protein GB3. The conducting polarizable continuum model was employed to include the effect of solvent in the density functional calculations. Our calculations for NMA show that the augmentation of the polarizable continuum model with the explicit water molecules in the first solvation shell has a significant influence on isotropic {sup 15}N chemical shift but not as much on the chemical shift anisotropy. The difference in the isotropic chemical shift between the standard {beta}-sheet and {alpha}-helical conformations ranges from 0.8 to 6.2 ppm depending on the residue type, with the mean of 2.7 ppm. This is in good agreement with the experimental chemical shifts averaged over a database of 36 proteins containing >6100 amino acid residues. The orientation of the {sup 15}N chemical shielding tensor as well as its anisotropy and asymmetry are also in the range of values experimentally observed for peptides and proteins.

  16. Alpine ecosystems

    Science.gov (United States)

    P.W. Rundel; C.I. Millar

    2016-01-01

    Alpine ecosystems are typically defined as those areas occurring above treeline, while recognizing that alpine ecosystems at a local scale may be found below this boundary for reasons including geology, geomorphology, and microclimate. The lower limit of the alpine ecosystems, the climatic treeline, varies with latitude across California, ranging from about 3500 m in...

  17. The nature of the dietary protein impacts the tissue-to-diet 15N discrimination factors in laboratory rats.

    Science.gov (United States)

    Poupin, Nathalie; Bos, Cécile; Mariotti, François; Huneau, Jean-François; Tomé, Daniel; Fouillet, Hélène

    2011-01-01

    Due to the existence of isotope effects on some metabolic pathways of amino acid and protein metabolism, animal tissues are (15)N-enriched relative to their dietary nitrogen sources and this (15)N enrichment varies among different tissues and metabolic pools. The magnitude of the tissue-to-diet discrimination (Δ(15)N) has also been shown to depend on dietary factors. Since dietary protein sources affect amino acid and protein metabolism, we hypothesized that they would impact this discrimination factor, with selective effects at the tissue level. To test this hypothesis, we investigated in rats the influence of a milk or soy protein-based diet on Δ(15)N in various nitrogen fractions (urea, protein and non-protein fractions) of blood and tissues, focusing on visceral tissues. Regardless of the diet, the different protein fractions of blood and tissues were generally (15)N-enriched relative to their non-protein fraction and to the diet (Δ(15)N>0), with large variations in the Δ(15)N between tissue proteins. Δ(15)N values were markedly lower in tissue proteins of rats fed milk proteins compared to those fed soy proteins, in all sampled tissues except in the intestine, and the amplitude of Δ(15)N differences between diets differed between tissues. Both between-tissue and between-diet Δ(15)N differences are probably related to modulations of the relative orientation of dietary and endogenous amino acids in the different metabolic pathways. More specifically, the smaller Δ(15)N values observed in tissue proteins with milk than soy dietary protein may be due to a slightly more direct channeling of dietary amino acids for tissue protein renewal and to a lower recycling of amino acids through fractionating pathways. In conclusion, the present data indicate that natural Δ(15)N of tissue are sensitive markers of the specific subtle regional modifications of the protein and amino acid metabolism induced by the protein dietary source.

  18. [Photobiological properties of 13,15-N-(carboxymethyl)- and 13,15-N-(2-carboxyethyl)cycloimide derivatives of chlorin p6].

    Science.gov (United States)

    Feofanov, A V; Nazarova, A I; Karmakova, T A; Pliutinskaia, A D; Grishin, A I; Iakubovskaia, R I; Lebedeva, V S; Ruziev, R D; Mironov, A F; Maurizot, J C; Vigny, P

    2004-01-01

    Lipophilic derivatives of chlorin p6, 13,15-N-(carboxymethyl)cycloimide methyl ester (CIC1) and 13,15-N-(2-carboxyethyl)cycloimide methyl ester (CIC2), were shown to absorb light in 710 nm region and to be efficient IR photosensitizers. They exhibit similar phototoxicities on the cells of A549 human lung adenocarcinoma, which are 40- and 100-fold higher than those of chlorin p6 and the clinically used Photogem, respectively, and are not toxic in the absence of light irradiation. The confocal spectral imaging technique allowed us to demonstrate that the high phototoxicity of CIC1 and CIC2 is due to their ability to readily penetrate to cells and to be bound to the cell membranes and lipid-containing structures in the monomeric photoactive form. Under the irradiation, the membrane-bound CIC1 and CIC2 are characterized by high quantum yields of singlet oxygen generation (0.6 and 0.65, respectively) and the inability to produce hydroxyl radicals. A 1.5-microM content of CIC1 and CIC2 in the incubation medium provides for their average cytoplasmic concentrations of 21 and 16.5 microM, respectively. The incubation times to achieve 50% level of maximum accumulation for CIC1 and CIC2 in A549 cells are 30 +/- 6 and 24 +/- 12 min, and the times for 50% release of the dyes from the cells are 17 +/- 4 and 50 +/- 10 min, respectively. A diffuse distribution with the predominant accumulation in the membranes of the Golgi apparatus and mitochondria is characteristic of both CIC2 and CIC1, whereas, in addition, CIC1 is considerably accumulated in lipid droplets (cellular organelles responsible for the storage and metabolism of neutral lipids and steryl esters). Our results demonstrate that changes in the structure of the imide substituent could affect the intracellular localization and the rate of release of chlorin p6 cycloimide derivatives from cells while preserving their high photodynamic activity.

  19. Utilization of residual nitrogen ({sup 15}N) from cover crop and urea by corn; Utilizacao do nitrogenio ({sup 15}N) residual de coberturas de solo e da ureia pela cultura do milho

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Edson Cabral da; Muraoka, Takashi; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil)]. E-mail: ecsilva@cena.usp.br; muraoka@cena.usp.br; pcotrive@cena.usp.br; Buzetti, Salatier [UNESP, Ilha Solteira, SP (Brazil). Faculdade de Engenharia (FEIS). Dept. de Fitossanidade, Engenharia Rural e Solos]. E-mail: sbuzetti@agr.feis.unesp.br; Guimaraes, Geovane Lima [UNESP, Ilha Solteira, SP (Brazil). Faculdade de Engenharia (FEIS)]. E-mail: geovanegui@aluno.feis.unesp.br; Veloso, Marcos Emanuel da Costa [Universidade de Sao Paulo (USP), Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz (ESALQ)]. E-mail: meveloso@esalq.usp.br

    2006-11-15

    The majority of N from mineral fertilizers and cover crops is usually not used by the very next corn crop, but can be absorbed by follow-up crops. The objective of this study was to evaluate the use of residual nitrogen from urea, sunnhemp (Crotalaria juncea) and millet (Pennisetum americanum) labeled with {sup 15}N, applied to no-tillage corn in the previous growing season, in a Red Latosol of the Cerrado. The study was conducted in an experimental farm of the Sao Paulo State University (UNESP), Ilha Solteira, in Selviria county (MS), Brazil, in different areas. The experiment had a randomized complete block design, with 15 treatments and four replications. Treatments were applied to corn crop in the 2001/02 and 2003/04 growing seasons. They were distributed in a 3 x 5 factorial layout, representing the combination of three cover crops: sunnhemp, millet and spontaneous vegetation (fallow) and five N rates (as urea): 0, 30, 80, 130, and 180 kg ha-1 of N. After corn harvest, the two areas were followed in the dry season and were followed by corn crop in the 2002/03 (experiment 1) and 2003/04 (experiment 2) growing seasons, using the same fertilizer rate on all plots to distinguish the residual effect of N sources. The average use of residual N from the millet and sunnhemp residues (above-ground part) by corn crop was less than 3.5 and 3 %, respectively, of the initial amount. The corn uptake of residual N from urea increased in a quadratic manner in experiment 1 and linearly in experiment Two as a response to the applied N rates, and the recover was below 3 %. The cover crop type did not affect the use of residual N of urea by corn, and vice-versa. (author)

  20. The Influence of Seed-borne N in 15N Isotope Dilution Studies with Legumes The Influence of Seed-borne N in 15N Isotope Dilution Studies with Legumes

    DEFF Research Database (Denmark)

    Jensen, Erik Steen; Andersen, A. J.; Thomsen, J. D.

    1985-01-01

    The distriution of seed-borne N in shoot and root of pea and field bean was studied using three methods: 1) determination of the N content in shoot and root of plants grown in sand culture without other N sources. 2) 15N isotope dilution in plants grown in Rhizobium-free medium supplied with 15N-...

  1. Nitrogen accumulation and partitioning in a High Arctic tundra ecosystem from extreme atmospheric N deposition events

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, Sonal, E-mail: S.Choudhary@sheffield.ac.uk [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Management School, University of Sheffield, Conduit Road, Sheffield S10 1FL (United Kingdom); Blaud, Aimeric [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Osborn, A. Mark [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); School of Applied Sciences, RMIT University, PO Box 71, Bundoora, VIC 3083 (Australia); Press, Malcolm C. [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Manchester Metropolitan University, Manchester, M15 6BH (United Kingdom); Phoenix, Gareth K. [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom)

    2016-06-01

    Arctic ecosystems are threatened by pollution from recently detected extreme atmospheric nitrogen (N) deposition events in which up to 90% of the annual N deposition can occur in just a few days. We undertook the first assessment of the fate of N from extreme deposition in High Arctic tundra and are presenting the results from the whole ecosystem {sup 15}N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2 g N m{sup −2} yr{sup −1}, applied as {sup 15}NH{sub 4}{sup 15}NO{sub 3} in Svalbard (79{sup °}N), during the summer. Separate applications of {sup 15}NO{sub 3}{sup −} and {sup 15}NH{sub 4}{sup +} were also made to determine the importance of N form in their retention. More than 95% of the total {sup 15}N applied was recovered after one growing season (~ 90% after two), demonstrating a considerable capacity of Arctic tundra to retain N from these deposition events. Important sinks for the deposited N, regardless of its application rate or form, were non-vascular plants > vascular plants > organic soil > litter > mineral soil, suggesting that non-vascular plants could be the primary component of this ecosystem to undergo measurable changes due to N enrichment from extreme deposition events. Substantial retention of N by soil microbial biomass (70% and 39% of {sup 15}N in organic and mineral horizon, respectively) during the initial partitioning demonstrated their capacity to act as effective buffers for N leaching. Between the two N forms, vascular plants (Salix polaris) in particular showed difference in their N recovery, incorporating four times greater {sup 15}NO{sub 3}{sup −} than {sup 15}NH{sub 4}{sup +}, suggesting deposition rich in nitrate will impact them more. Overall, these findings show that despite the deposition rates being extreme in statistical terms, biologically they do not exceed the capacity of tundra to sequester pollutant N during the growing season. Therefore, current and future extreme events

  2. Combining ambiguous chemical shift mapping with structure-based backbone and NOE assignment from 15N-NOESY

    KAUST Repository

    Jang, Richard

    2011-01-01

    Chemical shift mapping is an important technique in NMRbased drug screening for identifying the atoms of a target protein that potentially bind to a drug molecule upon the molecule\\'s introduction in increasing concentrations. The goal is to obtain a mapping of peaks with known residue assignment from the reference spectrum of the unbound protein to peaks with unknown assignment in the target spectrum of the bound protein. Although a series of perturbed spectra help to trace a path from reference peaks to target peaks, a one-to-one mapping generally is not possible, especially for large proteins, due to errors, such as noise peaks, missing peaks, missing but then reappearing, overlapped, and new peaks not associated with any peaks in the reference. Due to these difficulties, the mapping is typically done manually or semi-automatically. However, automated methods are necessary for high-throughput drug screening. We present PeakWalker, a novel peak walking algorithm for fast-exchange systems that models the errors explicitly and performs many-to-one mapping. On the proteins: hBclXL, UbcH5B, and histone H1, it achieves an average accuracy of over 95% with less than 1.5 residues predicted per target peak. Given these mappings as input, we present PeakAssigner, a novel combined structure-based backbone resonance and NOE assignment algorithm that uses just 15N-NOESY, while avoiding TOCSY experiments and 13C- labeling, to resolve the ambiguities for a one-toone mapping. On the three proteins, it achieves an average accuracy of 94% or better. Copyright © 2011 ACM.

  3. Combining automated peak tracking in SAR by NMR with structure-based backbone assignment from 15N-NOESY

    KAUST Repository

    Jang, Richard

    2012-03-21

    Background: Chemical shift mapping is an important technique in NMR-based drug screening for identifying the atoms of a target protein that potentially bind to a drug molecule upon the molecule\\'s introduction in increasing concentrations. The goal is to obtain a mapping of peaks with known residue assignment from the reference spectrum of the unbound protein to peaks with unknown assignment in the target spectrum of the bound protein. Although a series of perturbed spectra help to trace a path from reference peaks to target peaks, a one-to-one mapping generally is not possible, especially for large proteins, due to errors, such as noise peaks, missing peaks, missing but then reappearing, overlapped, and new peaks not associated with any peaks in the reference. Due to these difficulties, the mapping is typically done manually or semi-automatically, which is not efficient for high-throughput drug screening.Results: We present PeakWalker, a novel peak walking algorithm for fast-exchange systems that models the errors explicitly and performs many-to-one mapping. On the proteins: hBclXL, UbcH5B, and histone H1, it achieves an average accuracy of over 95% with less than 1.5 residues predicted per target peak. Given these mappings as input, we present PeakAssigner, a novel combined structure-based backbone resonance and NOE assignment algorithm that uses just 15N-NOESY, while avoiding TOCSY experiments and 13C-labeling, to resolve the ambiguities for a one-to-one mapping. On the three proteins, it achieves an average accuracy of 94% or better.Conclusions: Our mathematical programming approach for modeling chemical shift mapping as a graph problem, while modeling the errors directly, is potentially a time- and cost-effective first step for high-throughput drug screening based on limited NMR data and homologous 3D structures. 2012 Jang et al.; licensee BioMed Central Ltd.

  4. Annual variation of natural 15N abundance in tea leaves and its practicality as an organic tea indicator.

    Science.gov (United States)

    Hayashi, Nobuyuki; Ujihara, Tomomi; Tanaka, Eri; Kishi, Yasuhiro; Ogawa, Hideyuki; Matsuo, Hirofumi

    2011-09-28

    To obtain basic knowledge about the relationship between the application of organic fertilizers and the δ15N values of leaves of organically grown tea plants, annual variations in the δ15N values of the tea leaves were investigated. Although variations did not immediately arise after the application of organic fertilizers, differences in the δ15N values between organic and conventional cultivations appeared basically after three years from the beginning of the organic cultivation except when an organic fertilizer with a low δ15N value was applied, and the variation depended on the δ15N values of the fertilizers. In addition, the effectiveness of the δ15N values as a practical indicator of organic teas was examined. The tea leaves collected from organic farms did not always have higher δ15N values than the commercially available nonorganic teas. This result demonstrates that it is not easy to discriminate organic teas from nonorganic teas simply by their δ15N values.

  5. Distribution of nitrogen ammonium sulfate ({sup 15}N) soil-plant system in a no-tillage crop succession; Distribuicao do nitrogenio do sulfato de amonio ({sup 15}N) no sistema solo-planta, em uma sucessao de culturas, sob sistema plantio direto

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Flavia Carvalho da Silva, E-mail: flcsfernandes@gmail.com [Universidade Estadual de Maringa - Campus de Umuarama, PR (Brazil); Libardi, Paulo Leonel, E-mail: pllibard@esalq.usp.br [Departamento de Engenharia de Biossistemas, Escola Superior de Agricultura Luiz de Queiroz, Piracicaba, SP (Brazil)

    2012-05-15

    the n use by maize (Zea mays, l.) is affected by n-fertilizer levels. this study was conducted using a sandy-clay texture soil (Hapludox) to evaluate the efficiency of n use by maize in a crop succession, based on {sup 15}N labeled ammonium sulfate (5.5 atom %) at different rates, and to assess the residual fertilizer effect in two no-tillage succession crops (signal grass and corn). Two maize crops were evaluated, the first in the growing season 2006, the second in 2007, and brachiaria in the second growing season. The treatments consisted of n rates of 60, 120 and 180 kg ha{sup -1}in the form of labeled {sup 15}N ammonium sulfate. This fertilizer was applied in previously defined subplots, only to the first maize crop (growing season 2006). The variables total accumulated n; fertilizer-derived n in corn plants and pasture; fertilizer-derived n in the soil; and recovery of fertilizer-n by plants and soil were evaluated.The highest uptake of fertilizer n by corn was observed after application of 120 kg ha{sup -1}N and the residual effect of n fertilizer on subsequent corn and brachiaria was highest after application of 180 kg ha{sup -1}N. After the crop succession, soil n recovery was 32, 23 and 27 % for the respective applications of 60, 120 and 180 kg ha{sup -1}N. (author)

  6. Characterization of Atmospheric Nitrate Dynamics in a Sub-Alpine Watershed Using Δ17O and δ15N

    Science.gov (United States)

    Bourgeois, I.; Savarino, J. P.; Clement, J. C.

    2015-12-01

    Remote subalpine ecosystems are usually characterized by nutrient-poor soils (Körner, 2004; Seastedt et al., 2004), making them particularly susceptible to undergo changes due to increased atmospheric N deposition (Vitousek et al., 1997; Preunkert et al., 2003). Using Δ17O, a conserved tracer of atmospheric nitrate (NO3 atm) (Michalski et al., 2004; Tsunogai et al., 2010), and δ15N, indicator of NO3 biological sources (Kendall, 1998; Casciotti et al., 2009), we measured the seasonal variations of NO3 atm stable isotopic composition and concentration in several streams and soils originating from two sub-alpine watersheds in the French Alps. Our objective was to investigate whether or not NO3 atm impacts the soil N biogeochemical cycle by increasing nutrients availability for plants and bacteria. We coupled streams and soils measurements with snow-pits sampling and aerosols collection at the Lautaret Pass, to better emphasize the correlation between atmospheric deposition, soil retention and watersheds effluents response. Our results reveal that different temporal dynamics govern our study site: stream measurements show that in spring, snowmelt results in a NO3 atm impulse, accounting for ca. 31 % of the total stream NO3 budget; on the opposite in autumn, NO3 atm accounts only for ca. 3 % of the total stream NO3 budget, highlighting the presence of a NO3 bacterial pool (nitrification). We also inferred from the observed Δ17O variations two distinct phenomena in the spring/summer season: a fast snow run-off and a slower snow-water percolation. The later is believed to affect most the soil N cycle as it directly increases available NO3. Measured soil leachates and extracts confirm this hypothesis and point out the potential importance of anthropogenic N deposition as on average 7 to 10 % of the soil solutions NO3 derives directly from the atmosphere.

  7. Effect of estrogens on urinary /sup 15/N balance in girls

    Energy Technology Data Exchange (ETDEWEB)

    Zachmann, M.; Kempken, B.; Prader, A. (Zurich Univ. (Switzerland))

    1984-08-01

    While the anabolic and growth-promoting effects of testosterone are known to be important for pubertal growth in boys, the role of estrogens (E) in the female spurt is less certain. Adrenal androgens have been considered to be more important than ovarian E. To study the anabolic effects of E, there has been carried out a pilot study in 9 girls aged 11 to 15 years. Before and 6 days after the start of E treatment, urinary /sup 15/N balance studies were performed, using /sup 15/NH/sub 4/Cl.

  8. Spin Resonance Clock Transition of the Endohedral Fullerene 15N @ C60

    Science.gov (United States)

    Harding, R. T.; Zhou, S.; Zhou, J.; Lindvall, T.; Myers, W. K.; Ardavan, A.; Briggs, G. A. D.; Porfyrakis, K.; Laird, E. A.

    2017-10-01

    The endohedral fullerene 15N @ C60 has narrow electron paramagnetic resonance lines which have been proposed as the basis for a condensed-matter portable atomic clock. We measure the low-frequency spectrum of this molecule, identifying and characterizing a clock transition at which the frequency becomes insensitive to magnetic field. We infer a linewidth at the clock field of 100 kHz. Using experimental data, we are able to place a bound on the clock's projected frequency stability. We discuss ways to improve the frequency stability to be competitive with existing miniature clocks.

  9. Aqua ammonia {sup 15} N obtaining and application with vainness for sugar-cane fertilization

    Energy Technology Data Exchange (ETDEWEB)

    Vitti, Andre Cesar; Trivellin, Paulo Cesar O.; Oliveira, Claudineia R. de; Bendassoli, Jose A. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil)]. E-mail: acvitti@cena.usp.br

    2000-07-01

    Nitrogen compounds marked with the isotope {sup 15} N are continuously being used in agronomic studies and, when associated to the isotopic dilution technique, they constitute an important tool in clarifying the N cycle. At the Centro de Energia Nuclear na Agricultura (CENA/USP), it was obtained ( {sup 15} NH{sub 4}){sub 2}SO{sub 4} enhanced at 3,5% of {sup 15} N atoms, by means of the ionic exchange chromatography technique, which made possible to produce aqua ammonia ({sup 15} NH{sub 3}aq). Four repetitions were taken to the aqua ammonia production process to use the nitrogen compound in the field experiment. In each process 150g of ammonium sulfate enhanced at 3,5% of {sup 15} N atoms was used, obtaining 31,0 {+-} 1,6 g of aqua ammonia on the average (80% yield), with the same enhancement. The incidence of isotopic dilution has not been observed during the procedure, what made the use of such methodology possible. After obtaining the aqua ammonia {sup 15} N through this procedure, it was added to the vinasse (an equivalent to 50 m{sup 3} ha{sup -1} ) in doses that corresponded to 70 kg ha{sup -1} of N-NH{sub 3}aq. The mixture was applied to the sugar-cane straw on the soil's surface, aimed to the crop's fertilization. The compound's isotopic composition was analyzed by means of a spectrometer of masses ANCA-SL Europe Scientific, while the total-N volatilized, by the micro-Kjeldahl. Method. In accordance to the low NH{sub 3} (6,4 {+-} 1,9 kg ha{sup -1} ) volatilization results, it could be concluded that the application of vinasse and aqua ammonia mixture to the straw on the soil's surface was efficient, due to the vinasse's acid character, which allowed the NH{sub 3}, in presence of the ion H{sup +}, to stay in the NH{sub 4}{sup +} form in solution. (author)

  10. Optical Microscopy Characterization for Borehole U-15n#12 in Support of NCNS Source Physics Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Jennifer E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sussman, Aviva Joy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-05-22

    Optical microscopy characterization of thin sections from corehole U-15n#12 is part of a larger material characterization effort for the Source Physics Experiment (SPE). The SPE program was conducted in Nevada with a series of explosive tests designed to study the generation and propagation of seismic waves inside Stock quartz monzonite. Optical microscopy analysis includes the following: 1) imaging of full thin sections (scans and mosaic maps); 2) high magnification imaging of petrographic texture (grain size, foliations, fractures, etc.); and 3) measurement of microfracture density.

  11. Binding of oxytocin and 8-arginine-vasopressin to neurophysin studied by /sup 15/N NMR using magnetization transfer and indirect detection via protons

    Energy Technology Data Exchange (ETDEWEB)

    Live, D.H.; Cowburn, D.

    1987-10-06

    NMR was used to monitor the binding to neurophysin of oxytocin and 8-arginine-vasopressin, /sup 15/N labeling being used to identify specific backbone /sup 15/N and /sup 1/H signals. The most significant effects of binding were large downfield shifts in the amino nitrogen resonance of Phe-3 of vasopressin and in its associated proton, providing evidence that the peptide bond between residues 2 and 3 of the hormones is hydrogen-bonded to the protein within hormone-neurophysin complexes. Suggestive evidence for hydrogen bonding of the amino nitrogen of Tyr-2 was also obtained in the form of decreased proton exchange rates on binding; however, the chemical shift changes of this nitrogen and its associated proton indicated that such hydrogen bonding, if present, is probably weak. Shifts in the amino nitrogen of Asn-5 and in the -NH protons of both Asn-5 and Cys-6 demonstrated that these residues are significantly perturbed by binding, suggesting conformational changes of the ring on binding and/or the presence of binding sites on the hormone outside the 1-3 region. No support was obtained for the thesis that there is a significant second binding site for vasopressin on each neutrophysin chain. The behavior of both oxytocin and vasopressin on binding was consistent with formation of 1:1 complexes in slow exchange with the free state under most pH conditions. At low pH there was evidence of an increased exchange rate. Additionally, broadening of /sup 15/N resonances in the bound state at low pH occurred without a corresponding change in the resonances of equilibrating free hormone. The results suggest significant conformational alteration in neurophysin-hormone complexes at low pH possibly associated with protonation of the carboxyl group of the hormone-protein salt bridge.

  12. Alkaline hydrolysis/polymerization of 2,4,6-Trinitrotoluene:  Characterization of products by 13C and 15N NMR

    Science.gov (United States)

    Thorn, Kevin A.; Thorne, Philip G.; Cox, Larry G.

    2004-01-01

    Alkaline hydrolysis has been investigated as a nonbiological procedure for the destruction of 2,4,6-trinitrotoluene (TNT) in explosives contaminated soils and munitions scrap. Nucleophilic substitutions of the nitro and methyl groups of TNT by hydroxide ion are the initial steps in the alkaline degradation of TNT. Potential applications of the technique include both in situ surface liming and ex situ alkaline treatment of contaminated soils. A number of laboratory studies have reported the formation of an uncharacterized polymeric material upon prolonged treatment of TNT in base. As part of an overall assessment of alkaline hydrolysis as a remediation technique, and to gain a better understanding of the chemical reactions underlying the hydrolysis/polymerization process, the soluble and precipitate fractions of polymeric material produced from the calcium hydroxide hydrolysis of unlabeled and 15N-labeled TNT were analyzed by elemental analysis and 13C and 15N nuclear magnetic resonance spectroscopy. Spectra indicated that reactions leading to polymerization included nucleophilic displacement of nitro groups by hydroxide ion, formation of ketone, carboxyl, alcohol, ether, and other aliphatic carbons, conversion of methyl groups to diphenyl methylene carbons, and recondensation of aromatic amines and reduced forms of nitrite, including ammonia and possibly hydroxylamine, into the polymer. Compared to the distribution of carbons in TNT as 14% sp3- and 86% sp2-hybridized, the precipitate fraction from hydrolysis of unlabeled TNT contained 33% sp3- and 67% sp2-hybridized carbons. The concentration of nitrogen in the precipitate was 64% of that in TNT. The 15N NMR spectra showed that, in addition to residual nitro groups, forms of nitrogen present in the filtrate and precipitate fractions include aminohydroquinone, primary amide, indole, imine, and azoxy, among others. Unreacted nitrite was recovered in the filtrate fraction. The toxicities and susceptibilities to

  13. Macroalgae δ15N values in well-mixed estuaries: Indicator of anthropogenic nitrogen input or macroalgae metabolism?

    Science.gov (United States)

    Raimonet, Mélanie; Guillou, Gaël; Mornet, Françoise; Richard, Pierre

    2013-03-01

    Although nitrogen stable isotope ratio (δ15N) in macroalgae is widely used as a bioindicator of anthropogenic nitrogen inputs to the coastal zone, recent studies suggest the possible role of macroalgae metabolism in δ15N variability. Simultaneous determinations of δ15N of dissolved inorganic nitrogen (DIN) along the land-sea continuum, inter-species variability of δ15N and its sensitivity to environmental factors are necessary to confirm the efficiency of macroalgae δ15N in monitoring nitrogen origin in mixed-use watersheds. In this study, δ15N of annual and perennial macroalgae (Ulva sp., Enteromorpha sp., Fucus vesiculosus and Fucus serratus) are compared to δ15N-DIN along the Charente Estuary, after characterizing δ15N of the three main DIN sources (i.e. cultivated area, pasture, sewage treatment plant outlet). During late winter and spring, when human activities produce high DIN inputs, DIN sources exhibit distinct δ15N signals in nitrate (NO) and ammonium (NH): cultivated area (+6.5 ± 0.6‰ and +9.0 ± 11.0‰), pasture (+9.2 ± 1.8‰ and +12.4‰) and sewage treatment plant discharge (+16.9 ± 8.7‰ and +25.4 ± 5.9‰). While sources show distinct δN- in this multiple source catchment, the overall mixture of NO sources - generally >95% DIN - leads to low variations of δN-NO at the mouth of the estuary (+7.7 to +8.4‰). Even if estuarine δN-NO values are not significantly different from pristine continental and oceanic site (+7.3‰ and +7.4‰), macroalgae δ15N values are generally higher at the mouth of the estuary. This highlights high anthropogenic DIN inputs in the estuary, and enhanced contribution of 15N-depleted NH in oceanic waters. Although seasonal variations in δN-NO are low, the same temporal trends in macroalgae δ15N values at estuarine and oceanic sites, and inter-species differences in δ15N values, suggest that macroalgae δ15N values might be modified by the metabolic response of macroalgae to environmental parameters (e

  14. A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

    Science.gov (United States)

    Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S

    2011-06-24

    The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

  15. Pesticide Labels

    Science.gov (United States)

    Pesticide labels translate results of our extensive evaluations of pesticide products into conditions, directions and precautions that define parameters for use of a pesticide with the goal of ensuring protection of human health and the environment.

  16. Structure and membrane interactions of the antibiotic peptide dermadistinctin K by multidimensional solution and oriented 15N and 31P solid-state NMR spectroscopy.

    Science.gov (United States)

    Verly, Rodrigo M; de Moraes, Cléria Mendonça; Resende, Jarbas M; Aisenbrey, Christopher; Bemquerer, Marcelo Porto; Piló-Veloso, Dorila; Valente, Ana Paula; Almeida, Fábio C L; Bechinger, Burkhard

    2009-03-18

    DD K, a peptide first isolated from the skin secretion of the Phyllomedusa distincta frog, has been prepared by solid-phase chemical peptide synthesis and its conformation was studied in trifluoroethanol/water as well as in the presence of sodium dodecyl sulfate and dodecylphosphocholine micelles or small unilamellar vesicles. Multidimensional solution NMR spectroscopy indicates an alpha-helical conformation in membrane environments starting at residue 7 and extending to the C-terminal carboxyamide. Furthermore, DD K has been labeled with (15)N at a single alanine position that is located within the helical core region of the sequence. When reconstituted into oriented phosphatidylcholine membranes the resulting (15)N solid-state NMR spectrum shows a well-defined helix alignment parallel to the membrane surface in excellent agreement with the amphipathic character of DD K. Proton-decoupled (31)P solid-state NMR spectroscopy indicates that the peptide creates a high level of disorder at the level of the phospholipid headgroup suggesting that DD K partitions into the bilayer where it severely disrupts membrane packing.

  17. Detection of open and closed conformations of tryptophan synthase by 15N-heteronuclear single-quantum coherence nuclear magnetic resonance of bound 1-15N-L-tryptophan.

    Science.gov (United States)

    Osborne, Andrew; Teng, Quincy; Miles, Edith Wilson; Phillips, Robert S

    2003-11-07

    1-15N-L-Tryptophan (1-15N-L-Trp) was synthesized from 15N-aniline by a Sandmeyer reaction, followed by cyclization to isatin, reduction to indole with LiAlH4, and condensation of the 15N-indole with L-serine, catalyzed by tryptophan synthase. 1-15N-L-Trp was complexed with wild-type tryptophan synthase and beta-subunit mutants, betaK87T, betaD305A, and betaE109D, in the absence or presence of the allosteric ligands sodium chloride and disodium alpha-glycerophosphate. The enzyme complexes were observed by 15N-heteronuclear single-quantum coherence nuclear magnetic resonance (15N-HSQC NMR) spectroscopy for the presence of 1-15N-L-Trp bound to the beta-active site. No 15N-HSQC signal was detected for 1-15N-L-Trp in 10 mm triethanolamine hydrochloride buffer at pH 8. 1-15N-L-Trp in the presence of wild-type tryptophan synthase in the absence or presence of 50 mm sodium chloride showed a cross peak at 10.25 ppm on the 1H axis and 129 ppm on the 15N axis as a result of reduced solvent exchange for the bound 1-15N-L-Trp, consistent with formation of a closed conformation of the active site. The addition of disodium alpha-glycerophosphate produced a signal twice as intense, suggesting that the equilibrium favors the closed conformation. 15N-HSQC NMR spectra of betaK87T and betaE109D mutant Trp synthase with 1-15N-L-Trp showed a similar cross peak either in the presence or absence of disodium alpha-glycerophosphate, indicating the preference for a closed conformation for these mutant proteins. In contrast, the betaD305A Trp synthase mutant only showed a 15N-HSQC signal in the presence of disodium alpha-glycerophosphate. Thus, this mutant Trp synthase favored an open conformation in the absence of disodium alpha-glycerophosphate but was able to form a closed conformation in the presence of disodium alpha-glycerophosphate. Our results demonstrate that the 15N-HSQC NMR spectra of 1-15N-L-Trp bound to Trp synthase can be used to determine the conformational state of mutant

  18. Precursor discrimination of designer drug benzylpiperazine using δ13C and δ15N stable isotopes.

    Science.gov (United States)

    Beckett, Nicola M; Grice, Darren I; Carter, James F; Cresswell, Sarah L

    2015-01-01

    Advances in analytical technology and emerging techniques have resulted in the increased exploitation of chemical and isotopic profiling for source linkage/discrimination of illicit drugs for forensic purposes. Although not routinely used for illicit drug investigations, such information has been obtained and its application demonstrated through the use of isotope ratio mass spectrometry (IRMS). There is a solid platform of research available relating to the isotopic analysis of methylenedioxymethamphetamine (MDMA) and methamphetamine (MA), however with the recently flourishing designer drug market it was of interest to examine the isotopic profiles of the popular 'party drug' benzylpiperazine hydrochloride (BZP·HCl). A preliminary analysis of δ13C and δ15N isotopic ratios in BZP·HCl products and corresponding synthetic intermediates (piperazine·HCl) synthesized in-house from three different precursor suppliers was conducted using IRMS. Analysis of the δ13C and δ15N isotopic data indicated that discrimination and correct grouping of all the intermediates and some of the product samples examined in this study were achievable. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

  19. MUSIC in Triple-Resonance Experiments: Amino Acid Type-Selective 1H- 15N Correlations

    Science.gov (United States)

    Schubert, Mario; Smalla, Maika; Schmieder, Peter; Oschkinat, Hartmut

    1999-11-01

    Amino acid type-selective triple-resonance experiments can be of great help for the assignment of protein spectra, since they help to remove ambiguities in either manual or automated assignment procedures. Here, modified triple-resonance experiments that yield amino acid type-selective 1H-15N correlations are presented. They are based on novel coherence transfer schemes, the MUSIC pulse sequence elements, that replace the initial INEPT transfer and are selective for XH2 or XH3 (X can be 15N or 13C). The desired amino acid type is thereby selected based on the topology of the side chain. Experiments for Gly (G-HSQC); Ala (A-HSQC); Thr, Val, Ile, and Ala (TAVI-HSQC); Thr and Ala (TA-HSQC), as well as Asn and Gln (N-HSQC and QN-HSQC), are described. The new experiments are recorded as two-dimensional experiments and therefore need only small amounts of spectrometer time. The performance of the experiments is demonstrated with the application to two protein domains.

  20. MUSIC in triple-resonance experiments: amino acid type-selective (1)H-(15)N correlations

    Science.gov (United States)

    Schubert; Smalla; Schmieder; Oschkinat

    1999-11-01

    Amino acid type-selective triple-resonance experiments can be of great help for the assignment of protein spectra, since they help to remove ambiguities in either manual or automated assignment procedures. Here, modified triple-resonance experiments that yield amino acid type-selective (1)H-(15)N correlations are presented. They are based on novel coherence transfer schemes, the MUSIC pulse sequence elements, that replace the initial INEPT transfer and are selective for XH(2) or XH(3) (X can be (15)N or (13)C). The desired amino acid type is thereby selected based on the topology of the side chain. Experiments for Gly (G-HSQC); Ala (A-HSQC); Thr, Val, Ile, and Ala (TAVI-HSQC); Thr and Ala (TA-HSQC), as well as Asn and Gln (N-HSQC and QN-HSQC), are described. The new experiments are recorded as two-dimensional experiments and therefore need only small amounts of spectrometer time. The performance of the experiments is demonstrated with the application to two protein domains. Copyright 1999 Academic Press.

  1. Constraining the S factor of 15N(p,g)16O at Astrophysical Energies

    CERN Document Server

    LeBlanc, P J; Goerres, J; Junker, M; Azuma, R; Beard, M; Bemmerer, D; Best, A; Broggini, C; Caciolli, A; Corvisiero, P; Costantini, H; Couder, M; deBoer, R; Elekes, Z; Falahat, S; Formicola, A; Fulop, Zs; Gervino, G; Guglielmetti, A; Gustavino, C; Gyurky, Gy; Kaeppeler, F; Kontos, A; Kuntz, R; Leiste, H; Lemut, A; Li, Q; Limata, B; Marta, M; Mazzocchi, C; Menegazzo, R; O'Brien, S; Palumbo, A; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Stech, E; Straniero, O; Strieder, F; Tan, W; Terrasi, F; Trautvetter, H P; Uberseder, E; Wiescher, M

    2010-01-01

    The 15N(p,g)16O reaction represents a break out reaction linking the first and second cycle of the CNO cycles redistributing the carbon and nitrogen abundances into the oxygen range. The reaction is dominated by two broad resonances at Ep = 338 keV and 1028 keV and a Direct Capture contribution to the ground state of 16O. Interference effects between these contributions in both the low energy region (Ep < 338 keV) and in between the two resonances (338 15N(p,g)16O reaction has been remeasured covering the energy range from Ep=1800 keV down to 130 keV. The results have been analyzed in the framework of a multi-level R-matrix theory and a S(0) value of 39.6 keV b has been found.

  2. Nitrogen limitation, 15N tracer retention, and growth response in intact and Bromus tectorum-invaded Artemisia tridentata ssp. wyomingensis communities

    Science.gov (United States)

    Witwicki, Dana L.; Doescher, Paul S.; Pyke, David A.; DeCrappeo, Nicole M.; Perakis, Steven S.

    2012-01-01

    Annual grass invasion into shrub-dominated ecosystems is associated with changes in nutrient cycling that may alter nitrogen (N) limitation and retention. Carbon (C) applications that reduce plant-available N have been suggested to give native perennial vegetation a competitive advantage over exotic annual grasses, but plant community and N retention responses to C addition remain poorly understood in these ecosystems. The main objectives of this study were to (1) evaluate the degree of N limitation of plant biomass in intact versus B. tectorum-invaded sagebrush communities, (2) determine if plant N limitation patterns are reflected in the strength of tracer 15N retention over two growing seasons, and (3) assess if the strength of plant N limitation predicts the efficacy of carbon additions intended to reduce soil N availability and plant growth. Labile C additions reduced biomass of exotic annual species; however, growth of native A. tridentata shrubs also declined. Exotic annual and native perennial plant communities had divergent responses to added N, with B. tectorum displaying greater ability to use added N to rapidly increase aboveground biomass, and native perennials increasing their tissue N concentration but showing little growth response. Few differences in N pools between the annual and native communities were detected. In contrast to expectations, however, more 15N was retained over two growing seasons in the invaded annual grass than in the native shrub community. Our data suggest that N cycling in converted exotic annual grasslands of the northern Intermountain West, USA, may retain N more strongly than previously thought.

  3. Hydroponic isotope labeling of entire plants and high-performance mass spectrometry for quantitative plant proteomics.

    Science.gov (United States)

    Bindschedler, Laurence V; Mills, Davinia J S; Cramer, Rainer

    2012-01-01

    Hydroponic isotope labeling of entire plants (HILEP) combines hydroponic plant cultivation and metabolic labeling with stable isotopes using (15)N-containing inorganic salts to label whole and mature plants. Employing (15)N salts as the sole nitrogen source for HILEP leads to the production of healthy-looking plants which contain (15)N proteins labeled to nearly 100%. Therefore, HILEP is suitable for quantitative plant proteomic analysis, where plants are grown in either (14)N- or (15)N-hydroponic media and pooled when the biological samples are collected for relative proteome quantitation. The pooled (14)N-/(15)N-protein extracts can be fractionated in any suitable way and digested with a protease for shotgun proteomics, using typically reverse phase liquid chromatography nanoelectrospray ionization tandem mass spectrometry (RPLC-nESI-MS/MS). Best results were obtained with a hybrid ion trap/FT-MS mass spectrometer, combining high mass accuracy and sensitivity for the MS data acquisition with speed and high-throughput MS/MS data acquisition, increasing the number of proteins identified and quantified and improving protein quantitation. Peak processing and picking from raw MS data files, protein identification, and quantitation were performed in a highly automated way using integrated MS data analysis software with minimum manual intervention, thus easing the analytical workflow. In this methodology paper, we describe how to grow Arabidopsis plants hydroponically for isotope labeling using (15)N salts and how to quantitate the resulting proteomes using a convenient workflow that does not require extensive bioinformatics skills.

  4. The degree of urbanization across the globe is not reflected in the δ(15)N of seagrass leaves.

    Science.gov (United States)

    Christiaen, Bart; Bernard, Rebecca J; Mortazavi, Behzad; Cebrian, Just; Ortmann, Alice C

    2014-06-30

    Many studies show that seagrass δ(15)N ratios increase with the amount of urbanization in coastal watersheds. However, there is little information on the relationship between urbanization and seagrass δ(15)N ratios on a global scale. We performed a meta-analysis on seagrass samples from 79 independent locations to test if seagrass δ(15)N ratios correlate with patterns of population density and fertilizer use within a radius of 10-200 km around the sample locations. Our results show that seagrass δ(15)N ratios are more influenced by intergeneric and latitudinal differences than the degree of urbanization or the amount of fertilizer used in nearby watersheds. The positive correlation between seagrass δ(15)N ratios and latitude hints at an underlying pattern in discrimination or a latitudinal gradient in the (15)N isotopic signature of nitrogen assimilated by the plants. The actual mechanisms responsible for the correlation between δ(15)N and latitude remain unknown. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Discrimination against 15N among recombinant inbred lines of Phaseolus vulgaris L. contrasting in phosphorus use efficiency for nitrogen fixation.

    Science.gov (United States)

    Lazali, Mohamed; Bargaz, Adnane; Carlsson, Georg; Ounane, Sidi Mohamed; Drevon, Jean Jacques

    2014-02-15

    Although isotopic discrimination processes during nitrogen (N) transformations influence the outcome of (15)N based quantification of N2 fixation in legumes, little attention has been given to the effects of genotypic variability and environmental constraints such as phosphorus (P) deficiency, on discrimination against (15)N during N2 fixation. In this study, six Phaseolus vulgaris recombinant inbred lines (RILs), i.e. RILs 115, 104, 34 (P deficiency tolerant) and 147, 83, 70 (P deficiency sensitive), were inoculated with Rhizobium tropici CIAT899, and hydroaeroponically grown with P-sufficient (250 μmol P plant(-1) week(-1)) versus P-deficient (75 μmol P plant(-1) week(-1)) supply. Two harvests were done at 15 (before nodule functioning) and 42 (flowering stage) days after transplanting. Nodulation, plant biomass, P and N contents, and the ratios of (15)N over total N content ((15)N/Nt) for shoots, roots and nodules were determined. The results showed lower (15)N/Nt in shoots than in roots, both being much lower than in nodules. P deficiency caused a larger decrease in (15)N/Nt in shoots (-0.18%) than in nodules (-0.11%) for all of the genotypes, and the decrease in shoots was greatest for RILs 34 (-0.33%) and 104 (-0.25%). Nodule (15)N/Nt was significantly related to both the quantity of N2 fixed (R(2)=0.96***) and the P content of nodules (R(2)=0.66*). We conclude that the discrimination against (15)N in the legume N2-fixing symbiosis of common bean with R. tropici CIAT899 is affected by P nutrition and plant genotype, and that the (15)N/Nt in nodules may be used to screen for genotypic variation in P use efficiency for N2 fixation. Copyright © 2013 Elsevier GmbH. All rights reserved.

  6. Structure and reactivity of lithium amides. /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies and colligative measurements of lithium diphenylamide and lithium diphenylamide-lithium bromide complex solvated by tetrahydrofuran

    Energy Technology Data Exchange (ETDEWEB)

    DePue, J.S.; Collum, D.B.

    1988-08-03

    /sup 6/Li, /sup 13/C, and /sup 15/N NMR spectroscopic studies of lithium diphenylamide in THF/hydrocarbon solutions (THF = tetrahydrofuran) detected two different species. /sup 6/Li and /sup 15/N NMR spectroscopic studies of (/sup 6/Li, /sup 15/N)lithium diphenylamide showed the species observed at low THF concentrations to be a cyclic oligomer. Structural analogies provided strong support for a dimer while colligative measurements at 0/degrees/C indicated the dimer to be di- or trisolvated. On the basis of the observed mass action effects, the species appearing at intermediate THF concentrations is assigned as a contact or solvent-separated ion-paired monomer. Lithium diphenylamide forms a 1:1 adduct with lithium bromide at low THF concentrations. A combination of /sup 6/Li-/sup 15/N double labeling studies and colligative measurements supports a trisolvated cyclic mixed dimer structure. Although detailed spectroscopic studies at elevated THF concentrations were precluded by high fluctionality, the similarity of the /sup 13/C chemical shifts of lithium diphenylamide in the presence and absence of lithium bromide provide indirect evidence that the mixed dimer undergoes a THF concentration dependent dissociation to the monomeric amide and free lithium bromide. 24 references, 9 figures, 2 tables.

  7. Food Label and You

    Medline Plus

    Full Text Available ... Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food Label and You Video Share Tweet Linkedin Pin it ... Game Show Review (Are You Smarter Than A Food Label?) The Food Label & You (full video) Introduction back ...

  8. Food Label and You

    Medline Plus

    Full Text Available ... Labeling Labeling & Nutrition The Food Label and You — Video Share Tweet Linkedin Pin it More sharing ... Road) Game Show Review (Are You Smarter Than A Food Label?) The Food Label & You (full video) ...

  9. Distribution of /sup 15/N fertilizer in field-lysimeters sown with garlic (Allium sativum) and foxtail millet (Setaria italica)

    Energy Technology Data Exchange (ETDEWEB)

    Lazzari, M.A. (Universidad Nacional del Sur, Bahia Blanca (Argentina). Dept. de Ciencas Agrarias)

    1982-01-01

    We examined the distribution of residual /sup 15/N and its uptake by a foxtail millet crop grown in field lysimeters following a previous garlic crop fertilized with either /sup 15/N-urea or /sup 15/N-ammonium sulphate. Garlic apparently removed more N from the lysimeters treated with urea-N than from those treated with (NH/sub 4/)/sub 2/SO/sub 4/. Fertilizer-N in the lysimeters was similar (ca. 32% of original) following millet harvest. About 16 per cent of both fertilizers in the lysimeters was removed by the millet.

  10. Evaluation of automated analysis of 15N and total N in plant material and soil

    DEFF Research Database (Denmark)

    Jensen, E.S.

    1991-01-01

    was lower than 0.1%. The CV of repeated analyses of N-15-labelled plant material and soil samples varied between 0.3% and 1.1%. The reproducibility of repeated total N analyses using the automated method was comparable to results obtained with a semi-micro Kjeldahl procedure. However, the automated method...

  11. Regional, seasonal and interspecific variation in 15N and 13C in sympatric mouse lemurs

    Science.gov (United States)

    Rakotondranary, S. Jacques; Struck, Ulrich; Knoblauch, Christian; Ganzhorn, Jörg U.

    2011-11-01

    Madagascar provides some of the rare examples where two or more primate species of the same genus and with seemingly identical niche requirements occur in sympatry. If congeneric primate species co-occur in other parts of the world, they differ in size in a way that is consistent with Hutchinson's rule for coexisting species, or they occupy different ecological niches. In some areas of Madagascar, mouse lemurs do not follow these "rules" and thus seem to violate one of the principles of community ecology. In order to understand the mechanisms that allow coexistence of sympatric congeneric species without obvious niche differentiation, we studied food composition of two identical sized omnivorous mouse lemur species, Microcebus griseorufus and M. murinus with the help of stable isotope analyses ( δ 15N and δ 13C). The two species are closely related sister species. During the rich season, when food seems abundant, the two species do not differ in their nitrogen isotope composition, indicating that the two species occupy the same trophic level. But they differ in their δ 13C values, indicating that M. griseorufus feeds more on C4 and CAM (Crassulacean-acid-metabolism) plants than M. murinus. During the lean season, M. murinus has lower δ 15N values, indicating that the two species feed at different trophic levels during times of food shortage. Hybrids between the two species showed intermediate food composition. The results reflect subtle differences in foraging or metabolic adaptations that are difficult to quantify by traditional observations but that represent possibilities to allow coexistence of species.

  12. Nitrogen use efficiency evaluation of aerobic rice under field capacity water potential using 15N isotopic tracer technique

    Science.gov (United States)

    Wahid, Ahmad Nazrul Abd; Rahim, Sahibin Abd; Rahim, Khairuddin Abdul; Harun, Abdul Rahim

    2015-09-01

    This study was carried out to evaluate the efficiency use of the nitrogen fertilizer on aerobic rice varieties MR219-4 and MR219-9 which were grown aerobically under field capacity water potential at the controlled environment area or shield house. Direct 15N isotope tracer method was used in this study, whereby the 15N isotope was utilized as a tracer for nitrogen nutrient uptake. 15N isotope presence in the samples is determined by using emission spectrometer analysis and percentage of total nitrogen is determined by using Kjeldahl method. 15N atom access value contained in the sample will be used in determining the effectiveness of the use of nitrogen in fertilizers through the specific calculation formulas. In this work, the data several data of nitrogen derived from fertilizer (Ndff), total nitrogen, nitrogen uptake and nitrogen use efficiency was obtained.

  13. Simplified synthesis of isotopically labeled 5,5-dimethyl-pyrroline N-oxide.

    Science.gov (United States)

    Leinisch, Fabian; Jiang, Jinjie; Deterding, Leesa J; Mason, Ronald P

    2011-10-10

    5,5-Dimethylpyrroline N-oxide (15N) and 5,5-di(trideuteromethyl)pyrroline N-oxide were synthesized from the respective isotopically labeled 2-nitropropane analogs obtained from the reaction of sodium nitrate with 2-halopropanes. This facile, straightforward process allows synthesizing isotopically labeled DMPO analogs in a 4-step reaction without special equipment.

  14. Simplified Synthesis of Isotopically Labeled 5,5-Dimethyl-pyrroline N-Oxide

    Directory of Open Access Journals (Sweden)

    Ronald P. Mason

    2011-10-01

    Full Text Available 5,5-Dimethylpyrroline N-oxide (15N and 5,5-di(trideuteromethylpyrroline N-oxide were synthesized from the respective isotopically labeled 2-nitropropane analogs obtained from the reaction of sodium nitrate with 2-halopropanes. This facile, straightforward process allows synthesizing isotopically labeled DMPO analogs in a 4-step reaction without special equipment.

  15. Variability in δ{sup 15}N of intertidal brown algae along a salinity gradient: Differential impact of nitrogen sources

    Energy Technology Data Exchange (ETDEWEB)

    Viana, Inés G., E-mail: inesgviana@gmail.com; Bode, Antonio

    2015-04-15

    While it is generally agreed that δ{sup 15}N of brown macroalgae can discriminate between anthropogenic and natural sources of nitrogen, this study provides new insights on net fractionation processes occurring in some of these species. The contribution of continental and marine sources of nitrogen to benthic macroalgae in the estuary-ria system of A Coruña (NW Spain) was investigated by analyzing the temporal (at a monthly and annual basis) and spatial (up to 10 km) variability of δ{sup 15}N in the macroalgae Ascophyllum nodosum and three species of the genus Fucus (F. serratus, F. spiralis and F. vesiculosus). Total nitrate and ammonium concentrations and δ{sup 15}N-DIN, along with salinity and temperature in seawater were also studied to address the sources of such variability. Macroalgal δ{sup 15}N and nutrient concentrations decreased from estuarine to marine waters, suggesting larger dominance of anthropogenic nitrogen sources in the estuary. However, δ{sup 15}N values of macroalgae were generally higher than those of ambient nitrogen at all temporal and spatial scales considered. This suggests that the isotopic composition of these macroalgae is strongly affected by fractionation during uptake, assimilation or release of nitrogen. The absence of correlation between macroalgal and water samples suggests that the δ{sup 15}N of the species considered cannot be used for monitoring short-term changes. But their long lifespan and slow turnover rates make them suitable to determine the impact of the different nitrogen sources integrated over long-time periods. - Highlights: • Variability of Fucacean δ{sup 15}N indicates N sources along a salinity gradient. • δ{sup 15}N of Fucaceae and seawater are not correlated at short time scales. • Isotopic fractionation in macroalgal tissue varies at seasonal and at local scale. • Fucacean species are suitable for monitoring chronic N loadings.

  16. Ecosystem functioning

    National Research Council Canada - National Science Library

    Jax, Kurt

    2010-01-01

    "In the face of decreasing biodiversity and ongoing global changes, maintaining ecosystem functioning is seen both as a means to preserve biological diversity as well as for safeguarding human well...

  17. δ(15)N Values in Crassostrea virginica Shells Provides Early Direct Evidence for Nitrogen Loading to Chesapeake Bay.

    Science.gov (United States)

    Black, H D; Andrus, C F T; Lambert, W J; Rick, T C; Gillikin, D P

    2017-03-10

    Crassostrea virginica is one of the most common estuarine bivalves in the United States' east coast and is frequently found in archaeological sites and sub-fossil deposits. Although there have been several sclerochronological studies on stable carbon and oxygen isotopes in the shells of this species, less is known about δ(15)N values within their shells, which could be a useful paleoenvironmental proxy to assess estuarine nitrogen dynamics. Modern C. virginica samples were collected in Chesapeake Bay for comparison with archaeological shells from nearby sites ranging in age from ~100 to 3,200 years old. Left valves were sampled by milling the hinge area and the resulting powder was analyzed for %N and δ(15)N values. Comparison of δ(15)N values between C. virginica shells shows relatively constant values from ~1250 BC to ~1800 AD. After ~1800 AD, there are rapid increases in (15)N enrichment in the shells, which continue to increase in value up to the modern shell values. The increase in δ(15)N values is evidence of early anthropogenic impact in Chesapeake Bay. These results corroborate the observation that coastal nitrogen pollution occurred earlier than the 19th century and support the use of oyster shell δ(15)N values as a useful environmental proxy.

  18. δ15N Values in Crassostrea virginica Shells Provides Early Direct Evidence for Nitrogen Loading to Chesapeake Bay

    Science.gov (United States)

    Black, H. D.; Andrus, C. F. T.; Lambert, W. J.; Rick, T. C.; Gillikin, D. P.

    2017-01-01

    Crassostrea virginica is one of the most common estuarine bivalves in the United States’ east coast and is frequently found in archaeological sites and sub-fossil deposits. Although there have been several sclerochronological studies on stable carbon and oxygen isotopes in the shells of this species, less is known about δ15N values within their shells, which could be a useful paleoenvironmental proxy to assess estuarine nitrogen dynamics. Modern C. virginica samples were collected in Chesapeake Bay for comparison with archaeological shells from nearby sites ranging in age from ~100 to 3,200 years old. Left valves were sampled by milling the hinge area and the resulting powder was analyzed for %N and δ15N values. Comparison of δ15N values between C. virginica shells shows relatively constant values from ~1250 BC to ~1800 AD. After ~1800 AD, there are rapid increases in 15N enrichment in the shells, which continue to increase in value up to the modern shell values. The increase in δ15N values is evidence of early anthropogenic impact in Chesapeake Bay. These results corroborate the observation that coastal nitrogen pollution occurred earlier than the 19th century and support the use of oyster shell δ15N values as a useful environmental proxy. PMID:28281649

  19. Correlation between the synthetic origin of methamphetamine samples and their {sup 15}N and {sup 13}C stable isotope ratios

    Energy Technology Data Exchange (ETDEWEB)

    Billault, Isabelle [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France)]. E-mail: Isabelle.Billault@univ-nantes.fr; Courant, Frederique [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Pasquereau, Leo [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Derrien, Solene [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Robins, Richard J. [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France); Naulet, Norbert [Laboratoire d' Analyse Isotopique et Electrochimique de Metabolismes, CNRS UMR6006, University of Nantes, BP 92208, 44322 Nantes (France)

    2007-06-12

    The active ingredient of ecstasy, N-methyl-3,4-methyldioxyphenylisopropylamine (MDMA) can be manufactured by a number of easy routes from simple precursors. We have synthesised 45 samples of MDMA following the five most common routes using N-precursors from 12 different origins and three different precursors for the aromatic moiety. The {sup 13}C and {sup 15}N contents of both the precursors and the MDMA samples derived therefrom were measured by isotope ratio mass spectrometry coupled to an elemental analyser (EA-IRMS). We show that within-pathway correlation between the {sup 15}N content of the precursor and that of the derived MDMA can be strong but that no general pattern of correlation can be defined. Rather, it is evident that the {delta} {sup 15}N values of MDMA are strongly influenced by a combination of the {delta} {sup 15}N values of the source of nitrogen used, the route by which the MDMA is synthesised, and the experimental conditions employed. Multivariate analysis (PCA) based on the {delta} {sup 15}N values of the synthetic MDMA and of the {delta} {sup 15}N and {delta} {sup 13}C values of the N-precursors leads to good discrimination between the majority of the reaction conditions tested.

  20. Elastic and inelastic scattering of {sup 15}N ions by {sup 9}Be at 84 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Rudchik, A.T., E-mail: rudchik@kinr.kiev.ua [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Chercas, K.A. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Kemper, K.W. [Physics Department, Florida State University, Tallahassee, FL 32306-4350 (United States); Rusek, K. [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Rudchik, A.A.; Herashchenko, O.V. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Koshchy, E.I. [Kharkiv National University, pl. Svobody 4, 61077 Kharkiv (Ukraine); Pirnak, Val.M. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Piasecki, E.; Trzcińska, A. [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Sakuta, S.B. [Russian Research Center “Kurchatov Institute”, Kurchatov Sq. 1, 123182 Moscow (Russian Federation); Siudak, R. [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland); Strojek, I. [National Center for Nuclear Researches, ul. Hoża 69, PL-00-681 Warsaw (Poland); Stolarz, A. [Heavy Ion Laboratory of Warsaw University, ul. L. Pasteura 5A, PL-02-093 Warsaw (Poland); Ilyin, A.P.; Ponkratenko, O.A.; Stepanenko, Yu.M.; Shyrma, Yu.O. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine); Szczurek, A. [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, PL-31-342 Cracow (Poland); Uleshchenko, V.V. [Institute for Nuclear Research, Ukrainian Academy of Sciences, Prospect Nauki 47, 03680 Kyiv (Ukraine)

    2016-03-15

    Angular distributions of the {sup 9}Be + {sup 15}N elastic and inelastic scattering were measured at E{sub lab}({sup 15}N) = 84 MeV (E{sub c.m.} = 31.5 MeV) for the 0–6.76 MeV states of {sup 9}Be and 0–6.32 MeV states of {sup 15}N. The data were analyzed within the optical model and coupled-reaction-channels method. The elastic and inelastic scattering, spin reorientations of {sup 9}Be in ground and excited states and {sup 15}N in excited states as well as the most important one- and two-step transfer reactions were included in the channels-coupling scheme. The parameters of the {sup 9}Be + {sup 15}N optical potential of Woods–Saxon form as well as deformation parameters of these nuclei were deduced. The analysis showed that the {sup 9}Be + {sup 15}N pure potential elastic scattering dominates at the forward angles whereas the ground state spin reorientation of {sup 9}Be gives a major contribution to the elastic scattering cross sections at the large angles. Contributions from particle transfers are found to be negligible for the present scattering system.

  1. δ15N Values in Crassostrea virginica Shells Provides Early Direct Evidence for Nitrogen Loading to Chesapeake Bay

    Science.gov (United States)

    Black, H. D.; Andrus, C. F. T.; Lambert, W. J.; Rick, T. C.; Gillikin, D. P.

    2017-03-01

    Crassostrea virginica is one of the most common estuarine bivalves in the United States’ east coast and is frequently found in archaeological sites and sub-fossil deposits. Although there have been several sclerochronological studies on stable carbon and oxygen isotopes in the shells of this species, less is known about δ15N values within their shells, which could be a useful paleoenvironmental proxy to assess estuarine nitrogen dynamics. Modern C. virginica samples were collected in Chesapeake Bay for comparison with archaeological shells from nearby sites ranging in age from ~100 to 3,200 years old. Left valves were sampled by milling the hinge area and the resulting powder was analyzed for %N and δ15N values. Comparison of δ15N values between C. virginica shells shows relatively constant values from ~1250 BC to ~1800 AD. After ~1800 AD, there are rapid increases in 15N enrichment in the shells, which continue to increase in value up to the modern shell values. The increase in δ15N values is evidence of early anthropogenic impact in Chesapeake Bay. These results corroborate the observation that coastal nitrogen pollution occurred earlier than the 19th century and support the use of oyster shell δ15N values as a useful environmental proxy.

  2. 15N/14N variations in Cretaceous Atlantic sedimentary sequences: implication for past changes in marine nitrogen biogeochemistry

    Science.gov (United States)

    Rau, G.H.; Arthur, M.A.; Dean, W.E.

    1987-01-01

    At two locations in the Atlantic Ocean (DSDP Sites 367 and 530) early to middle Cretaceous organic-carbon-rich beds ("black shales") were found to have significantly lower ??15N values (lower 15N/14N ratios) than adjacent organic-carbon-poor beds (white limestones or green claystones). While these lithologies are of marine origin, the black strata in particular have ??15N values that are significantly lower than those previously found in the marine sediment record and most contemporary marine nitrogen pools. In contrast, black, organic-carbon-rich beds at a third site (DSDP Site 603) contain predominantly terrestrial organic matter and have C- and N-isotopic compositions similar to organic matter of modern terrestrial origin. The recurring 15N depletion in the marine-derived Cretaceous sequences prove that the nitrogen they contain is the end result of an episodic and atypical biogeochemistry. Existing isotopic and other data indicate that the low 15N relative abundance is the consequence of pelagic rather than post-depositional processes. Reduced ocean circulation, increased denitrification, and, hence, reduced euphotic zone nitrate availability may have led to Cretaceous phytoplankton assemblages that were periodically dominated by N2-fixing blue-green algae, a possible source of this sediment 15N-depletion. Lack of parallel isotopic shifts in Cretaceous terrestrially-derived nitrogen (Site 603) argues that the above change in nitrogen cycling during this period did not extend beyond the marine environment. ?? 1987.

  3. Single Particle Strengths and Mirror States in $^{15}$N$-^{15}$O below 12.0 MeV

    CERN Document Server

    Mertin, C E; Crisp, A M; Keeley, N; Kemper, K W; Momtyuk, O; Roeder, B T; Volya, A

    2014-01-01

    New $^{14}$N(d,p) angular distribution data were taken at a deuteron bombarding energy of 16 MeV to locate all narrow single particle neutron states up to 15 MeV in excitation. A new shell model calculation is able to reproduce all levels in $^{15}$N up to 11.5 MeV and is used to characterize a narrow single particle level at 11.236 MeV and to provide a map of the single particle strengths. The known levels in $^{15}$N are then used to determine their mirrors in the lesser known nucleus $^{15}$O. The 2s$_{1/2}$ and 1d$_{5/2}$ single particle centroid energies are determined for the $^{15}$N$-^{15}$O mirror pair as: $^{15}$N $(\\text{2s}_{1/2}) = 8.08$ MeV, $^{15}$O $(\\text{2s}_{1/2}) = 7.43$ MeV, $^{15}$N $(\\text{1d}_{5/2}) = 7.97$ MeV, and $^{15}$O $(\\text{1d}_{5/2}) = 7.47$ MeV. These results confirm the degeneracy of these orbits and that the $^{15}$N$-^{15}$O nuclei are where the transition between the $\\text{2s}_{1/2}$ lying below the $\\text{1d}_{5/2}$ to lying above it, takes place. The $\\text{1d}_{3/2}$...

  4. Study of a case of essential hypoproteinaemia using the isotopes {sup 131}I and {sup 15}N; Etude a l'aide des isotopes {sup 131}I et {sup 15}N d'un cas d'hypoproteinemie essentielle

    Energy Technology Data Exchange (ETDEWEB)

    Dubert, A.; Coursaget, J.; Fallot, P.; Royer, P. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Hopital des Enfants Malades, 75 - Paris (France)

    1959-07-01

    Hypoproteinaemia both human and experimental has been studied with the help of nuclear labelling. A comparative study has been made of the fate of serum proteins labelled by an endogenous path after administration of nitrogen-15 glycine and also of serum albumin labelled by exogenous path using iodine-131. We have determined the biological period of the serum albumin and serum globulins and also the magnitude of the vascular and extravascular pools of serum albumin. In this way it has been possible to measure the speed of replacement of plasma proteins. A presentation of results taken from both clinical observation and experiment leads to a discussion on the pathogenic mechanism of hypoproteinaemia. (author) [French] Les hypoproteinemies humaine et experimentale ont ete explorees a l'aide d'indicateurs nucleaires. Une etude comparative du devenir des proteines seriques marquees par voie endogene, apres administration de glycocolle-{sup 15}N et de l'albumine serique marquee par voie exogene a l'iode-131 a ete realisee. On a determine la periode biologique de la serumalbumine et des globulines seriques ainsi que la grandeur des 'pools' vasculaire et extravasculaire de la serumalbumine. Il a ete ainsi possible d'evaluer la vitesse de renouvellement des proteines plasmatiques. La confrontation des resultats tires de l'observation clinique et de l'experimentation conduit a une discussion sur le mecanisme pathogenique de l'hypoproteinemie. (auteur)

  5. Recuperação de 15N-ureia no sistema solo-planta de pastagem de capim-tanzânia Recovery of 15N-urea in soil-plant system of tanzania grass pasture

    Directory of Open Access Journals (Sweden)

    Geraldo Bueno Martha Júnior

    2009-02-01

    Full Text Available O atrativo econômico e o impacto ambiental da adubação nitrogenada em pastagens dependem da eficiência de uso do nitrogênio (N do fertilizante no sistema solo-planta. Entretanto, a recuperação do 15N-ureia em pastagem de Panicum maximum cv. Tanzânia, uma das forrageiras mais utilizadas na intensificação de sistemas pastoris, permanece desconhecida. Este experimento, seguindo um delineamento de blocos completos casualizados, com quatro tratamentos (0, 40, 80 e 120 kg ha-1 de N-ureia e três repetições, foi realizado para determinar a recuperação do 15N-ureia pelo capim-tanzânia. A produção de forragem, o teor de N total e a quantidade de N na planta não foram afetados pelas doses de 15N-ureia, refletindo as elevadas perdas do N aplicado nas condições do experimento. Entretanto, a baixa eficiência agronômica do uso da ureia pode ser explicada pelo decréscimo da recuperação do N do fertilizante no sistema solo-planta com o aumento da dose de 15N-ureia em situações climáticas bastante adversas, que contribuíram para aumentar as perdas de 15N-ureia no sistema solo-planta.The economic attractiveness and negative environmental impact of nitrogen (N fertilization in pastures depend on the N use efficiency in the soil-plant system. However, the recovery of urea-15N by Panicum maximum cv. Tanzania pastures, one of the most widely used forage species in intensified pastoral systems, is still unknown. This experiment was conducted in a randomized complete block design with four treatments (0, 40, 80 and 120 kg ha-1 of N-urea and three replications, to determine the recovery of 15N urea by Tanzania grass. Forage production, total N content and N yield were not affected by fertilization (p > 0.05, reflecting the high losses of applied N under the experimental conditions. The recovery of 15N urea (% of applied N in forage and roots was not affected by fertilization levels (p > 0.05, but decreased exponentially in the soil and soil

  6. Influência do etil-trinexapac no acúmulo, na distribuição de nitrogênio (15N e na massa de grãos de arroz de terras altas Influence of ethyl-trinexapac on 15N accumulation and distribution and on highland rice yield

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Félix Alvarez

    2007-12-01

    regulador de crescimento vegetal reduziu a altura das plantas e o acúmulo de 15N na panícula e promoveu a redistribuição do 15N absorvido e o aumento do 15N acumulado na raiz, colmo+bainha e folhas. A contribuição de 15N absorvido, em cada estádio estudado, para formação da panícula aumentou com o desenvolvimento das plantas, em menor proporção na presença do regulador de crescimento utilizado. O etil-trinexapac influenciou negativamente os componentes do rendimento e a massa de grãos de arroz.The high rice grain yields ensured by sprinkler irrigation have encouraged the use of higher fertilizer doses, mainly the nitrogen fertilizers. However, an improper management of nitrogen fertilization may result in plant lodging. Application of plant regulators may redirect assimilates to grain production while limiting the vegetative growth. This study aimed to: evaluate the influence of the growth regulator Ethyl-trinexapac on plant growth parameters and on 15N accumulation and distribution in the whole plant and plant components, and determine the contribution of nitrogen taken up in different developmental stages in panicle formation, yield components and rice yield. The experiment was carried out under controlled greenhouse conditions. The treatments consisted of application or not of a plant growth regulator (0 and 200 g active ingredient ha-1 of ethyl-trinexapac at four plant development stages (1 - beginning to end of tillering; 2 - end of tillering and flower differentiation; 3 - flower differentiation to flowering; 4 - flowering until physiological maturation. The experimental design was arranged in random blocks, in a 2 x 4 factorial scheme, with three replications. The plants were placed in a group of 48 pots. In a group of 24 pots with nutrient solution containing 15NH4SO4, plants were collected and separated in parts in the beginning of each pre-established plant development stage and at the end of each stage. In a second group (24 pots, pre-labeled plants

  7. Food labels

    DEFF Research Database (Denmark)

    Selsøe Sørensen, Henrik; Clement, Jesper; Gabrielsen, Gorm

    2012-01-01

    The food industry develops tasty and healthy food but fails to deliver the message to all consumers. The consumers’ background knowledge is essential for how they find and decode relevant elements in the cocktail of signs which fight for attention on food labels. In this exploratory study, we find...... evidence for dividing consumers into two profiles: one relying on general food knowledge and another using knowledge related to signpost labels. In a combined eyetracking and questionnaire survey we analyse the influence of background knowledge and identify different patterns of visual attention...... for the two consumer profiles. This underlines the complexity in choosing and designing the ‘right’ elements for a food package that consumers actually look at and are able to make rational use of. In spite of any regulation of food information provided by authorities, consumers will still be confronted...

  8. Practical considerations for investigation of protein conformational dynamics by 15N R 1ρ relaxation dispersion.

    Science.gov (United States)

    Walinda, Erik; Morimoto, Daichi; Shirakawa, Masahiro; Sugase, Kenji

    2017-03-01

    It is becoming increasingly apparent that proteins are not static entities and that their function often critically depends on accurate sampling of multiple conformational states in aqueous solution. Accordingly, the development of methods to study conformational states in proteins beyond their ground-state structure ("excited states") has crucial biophysical importance. Here we investigate experimental schemes for optimally probing chemical exchange processes in proteins on the micro- to millisecond timescale by 15N R 1ρ relaxation dispersion. The schemes use selective Hartmann-Hahn cross-polarization (CP) transfer for excitation, and derive peak integrals from 1D NMR spectra (Korzhnev et al. in J Am Chem Soc 127:713-721, 2005; Hansen et al. in J Am Chem Soc 131:3818-3819, 2009). Simulation and experiment collectively show that in such CP-based schemes care has to be taken to achieve accurate suppression of undesired off-resonance coherences, when using weak spin-lock fields. This then (i) ensures that relaxation dispersion profiles in the absence of chemical exchange are flat, and (ii) facilitates extraction of relaxation dispersion profiles in crowded regions of the spectrum. Further improvement in the quality of the experimental data is achieved by recording the free-induction decays in an interleaved manner and including a heating-compensation element. The reported considerations will particularly benefit the use of CP-based R 1ρ relaxation dispersion to analyze conformational exchange processes in larger proteins, where resonance line overlap becomes the main limiting factor.

  9. Conformational analysis of capsaicin using 13C, 15N MAS NMR, GIAO DFT and GA calculations

    Science.gov (United States)

    Siudem, Paweł; Paradowska, Katarzyna; Bukowicki, Jarosław

    2017-10-01

    Capsaicin produced by plants from genus Capsicum exerts multiple pharmacological effects and has found applications in food and pharmaceutical industry. The alkaloid was studied by a combined approach: solid-state NMR, GA conformational search and GIAO DFT methods. The 13C CPMAS NMR spectra were recorded using variable contact time and dipolar dephasing experiments. The results of cross-polarization (CP) kinetics, such as TCP values and long T1ρH (100-200 ms), indicated that the capsaicin molecule is fairly mobile, especially at the end of the aliphatic chain. The15N MAS NMR spectrum showed one narrow signal at -255 ppm. Genetic algorithm (GA) search with multi modal optimization was used to find low-energy conformations of capsaicin. Theoretical GIAO DFT calculations were performed using different basis sets to characterize five selected conformations. 13C CPMAS NMR was used as a validation method and the experimental chemical shifts were compared with those calculated for selected stable conformers. Conformational analysis suggests that the side chain can be bent or extended. A comparison of the experimental and the calculated chemical shifts indicates that solid capsaicin does not have the same structure as those established by PWXRD.

  10. Prediction of human dietary δ15N intake from standardised food records: validity and precision of single meal and 24-h diet data.

    Science.gov (United States)

    Hülsemann, Frank; Koehler, Karsten; Wittsiepe, Jürgen; Wilhelm, Michael; Hilbig, Annett; Kersting, Mathilde; Braun, Hans; Flenker, Ulrich; Schänzer, Wilhelm

    2017-08-01

    Natural stable isotope ratios (δ15N) of humans can be used for nutritional analyses and dietary reconstruction of modern and historic individuals and populations. Information about an individual's metabolic state can be obtained by comparison of tissue and dietary δ15N. Different methods have been used to estimate dietary δ15N in the past; however, the validity of such predictions has not been compared to experimental values. For a total of 56 meals and 21 samples of 24-h diets, predicted and experimental δ15N values were compared. The δ15N values were predicted from self-recorded food intake and compared with experimental δ15N values. Predicted and experimental δ15N values were in good agreement for meals and preparations (r = 0.89, p Dietary δ15N was mainly determined by the amount of fish, whereas the contribution of meat to dietary δ15N values was less pronounced. Prediction of human dietary δ15N values using standardised food records and representative δ15N data sets yields reliable data for dietary δ15N intake. A differentiated analysis of the primary protein sources is necessary when relating the proportion of animal-derived protein in the diet by δ15N analysis.

  11. Mineralization and volatilization of nitrogen from vinasse-{sup 15} N in the presence or absence of urea and sugar cane straw; Mineralizacao e volatilizacao do nitrogenio da vinhaca-{sup 15} N na presenca ou nao de ureia e de palha de cana-de-acucar

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Vilma Maria; Colaco, Waldeciro [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear; Trivelin, Paulo Cesar Ocheuse [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil); Encarnacao, Fernando Antonio Franco da [Alagoas Univ., Maceio, AL (Brazil). Dept. de Geologia e Topografia; Cabezas, Waldo Alejandro Ruben Lara [Uberlandia Univ., MG (Brazil). Dept. de Agronomia

    1999-03-01

    The mineralized and volatilized nitrogen derived from vinasse labelled with {sup 15} N were determined in a laboratory experiment, using samples of two soils [a sandy Red-Yellow-Podzolic-PV and a clayey Latosol - LR (Oxisol)], collected in Piracicaba, SP, Brazil. The experiment consisted of four treatments: application of vinasse (V{sup *}); vinasse with urea (V{sup *}+U); vinasse with sugar cane straw (V{sup *}+P); and vinasse with urea and sugar cane straw (V{sup *}+U+P). Vinasse, labelled with {sup 15} N (V{sup *}) was applied at a rate of 100 mg.kg{sup -1} of N-vinasse. All treatments, were incubated for 7, 14, 21, 28 and 35 days. N-urea and sugar cane straw were incorporated in the soil at rates of 220 mg.kg{sup -1} and 22 g.kg{sup -1}, respectively. N H{sub 4}{sup +} -N and NO{sub 3}{sup -} -N concentrations, as a result of the vinasse addition, were affected by soil type. A larger availability of N H{sub 4}{sup +} -N and NO{sub 3}{sup -} -N derived from vinasse were observed, when urea was added. Sugar cane straw plus vinasse did not alter the concentrations of N H{sub 4}{sup +} - N and NO{sub 3}{sup -} - N derived from vinasse. Urea plus sugar cane straw did not affect N H{sub 4}{sup +} -N concentrations, and affected the NO{sub 3}{sup -} -N concentration in LR soil over time. Losses of vinasse-N, due to volatilization, increased with time for all treatments, and were larger for PV (14%) than for LR(5%); but such losses were similar in LR soil. (author)

  12. STELLAR ORIGINS OF EXTREMELY {sup 13}C- AND {sup 15}N-ENRICHED PRESOLAR SIC GRAINS: NOVAE OR SUPERNOVAE?

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Nan; Nittler, Larry R.; Alexander, Conel M. O’D.; Wang, Jianhua [Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC 20015 (United States); Pignatari, Marco [E.A. Milne Centre for Astrophysics, Department of Physics and Mathematics, University of Hull, HU6 7RX (United Kingdom); José, Jordi [Department de Fisica, EUETIB, Universitat Politécnica de Catalunya, E-08036 Barcelona (Spain); Nguyen, Ann, E-mail: nliu@carnegiescience.edu [Robert M. Walker Laboratory for Space Science, Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, TX 77058 (United States)

    2016-04-01

    Extreme excesses of {sup 13}C ({sup 12}C/{sup 13}C < 10) and {sup 15}N ({sup 14}N/{sup 15}N < 20) in rare presolar SiC grains have been considered diagnostic of an origin in classical novae, though an origin in core collapse supernovae (CCSNe) has also been proposed. We report C, N, and Si isotope data for 14 submicron- to micron-sized {sup 13}C- and {sup 15}N-enriched presolar SiC grains ({sup 12}C/{sup 13}C < 16 and {sup 14}N/{sup 15}N < ∼100) from Murchison, and their correlated Mg–Al, S, and Ca–Ti isotope data when available. These grains are enriched in {sup 13}C and {sup 15}N, but with quite diverse Si isotopic signatures. Four grains with {sup 29,30}Si excesses similar to those of type C SiC grains likely came from CCSNe, which experienced explosive H burning occurred during explosions. The independent coexistence of proton- and neutron-capture isotopic signatures in these grains strongly supports heterogeneous H ingestion into the He shell in pre-supernovae. Two of the seven putative nova grains with {sup 30}Si excesses and {sup 29}Si depletions show lower-than-solar {sup 34}S/{sup 32}S ratios that cannot be explained by classical nova nucleosynthetic models. We discuss these signatures within the CCSN scenario. For the remaining five putative nova grains, both nova and supernova origins are viable because explosive H burning in the two stellar sites could result in quite similar proton-capture isotopic signatures. Three of the grains are sub-type AB grains that are also {sup 13}C enriched, but have a range of higher {sup 14}N/{sup 15}N. We found that {sup 15}N-enriched AB grains (∼50 < {sup 14}N/{sup 15}N < ∼100) have distinctive isotopic signatures compared to putative nova grains, such as higher {sup 14}N/{sup 15}N, lower {sup 26}Al/{sup 27}Al, and lack of {sup 30}Si excess, indicating weaker proton-capture nucleosynthetic environments.

  13. Food Label and You

    Medline Plus

    Full Text Available ... Products Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food Label and You — Video Share ... FDA has issued final changes to update the Nutrition Facts label for packaged foods. For more information, ...

  14. Food Label and You

    Medline Plus

    Full Text Available ... Products Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food Label and You Video Share Tweet ... FDA has issued final changes to update the Nutrition Facts label for packaged foods. For more information, ...

  15. Food Label and You

    Medline Plus

    Full Text Available ... Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food Label and You — Video Share Tweet ... NOTE: FDA has issued final changes to update the Nutrition Facts label for packaged foods. For more ...

  16. Food Label and You

    Medline Plus

    Full Text Available ... Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food Label and You Video Share Tweet Linkedin ... NOTE: FDA has issued final changes to update the Nutrition Facts label for packaged foods. For more ...

  17. Impact of traffic on δ15N, δ13C and δ18O of needles and annual tree rings of Norway spruce (Picea abies L.

    Directory of Open Access Journals (Sweden)

    Guerrieri MR

    2006-01-01

    Full Text Available Increase of nitrogen depositions, as oxidized (NOx and reduced (NHx compounds, has important implications on ecosystem nitrogen cycle. NOx comes predominantly from fossil fuel combustion in car engines and industrial processes, while agricultural activities (cattle farming, fertilizations are the main sources for NHx emissions. Such fertilisations could stimulate growth and, therefore, productivity of forests, especially in temperate forests, where nitrogen is a limiting factor. On the other hand an excess of nitrogen can lead to an acidification of the soil and have a negative impact on the microbial fauna and structure of plants. NOx and NHx depositions can be separated with the help of stable isotopes with different 15N-values reported for NOx originating from combustion sources. Consequently it was observed that the nitrogen isotopic composition of the vegetation reflects the isotopic signature of nitrogen sources. Our preliminary results on needles of Norway spruce trees exposed to NOx emissions along a transect perpendicular to a highway close to Faido and Brittnau show a clear isotopic enrichment in 15N in trees growing closer to traffic pollution, indicating an uptake of atmospheric nitrogen by stomatal pathway. Carbon and oxygen isotopic composition measured in tree rings reveals the physiological response in plants. Trees more exposed to air pollution from traffic show an increase in δ13C and δ18O in tree rings, since mid sixties next to Erstfeld. This could mean a higher photosynthetic activity, enhanced by NOx traffic emissions, under low or not changed stomatal conductance. Our results confirm that stable isotopes of carbon, oxygen and nitrogen measured in needles and tree rings represent an important tool to monitor the impact of NOx load on tree physiology.

  18. Isotopic discrimination of stable isotopes of nitrogen (δ15N) and carbon (δ13C) in a host-specific holocephalan tapeworm.

    Science.gov (United States)

    Navarro, J; Albo-Puigserver, M; Coll, M; Saez, R; Forero, M G; Kutcha, R

    2014-09-01

    During the past decade, parasites have been considered important components of their ecosystems since they can modify food-web structures and functioning. One constraint to the inclusion of parasites in food-web models is the scarcity of available information on their feeding habits and host-parasite relationships. The stable isotope approach is suggested as a useful methodology to determine the trophic position and feeding habits of parasites. However, the isotopic approach is limited by the lack of information on the isotopic discrimination (ID) values of parasites, which is pivotal to avoiding the biased interpretation of isotopic results. In the present study we aimed to provide the first ID values of δ(15)N and δ(13)C between the gyrocotylidean tapeworm Gyrocotyle urna and its definitive host, the holocephalan Chimaera monstrosa. We also test the effect of host body size (body length and body mass) and sex of the host on the ID values. Finally, we illustrate how the trophic relationships of the fish host C. monstrosa and the tapeworm G. urna could vary relative to ID values. Similar to other studies with parasites, the ID values of the parasite-host system were negative for both isotopic values of N (Δδ(15)N = - 3.33 ± 0.63‰) and C (Δδ(13)C = - 1.32 ± 0.65‰), independent of the sex and size of the host. By comparing the specific ID obtained here with ID from other studies, we illustrate the importance of using specific ID in parasite-host systems to avoid potential errors in the interpretation of the results when surrogate values from similar systems or organisms are used.

  19. Pan-Arctic concentrations of mercury and stable isotope ratios of carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) in marine zooplankton

    Energy Technology Data Exchange (ETDEWEB)

    Pomerleau, Corinne, E-mail: corinne.pomerleau@umanitoba.ca [Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Greenland Institute of Natural Resources, Kivioq 2, Nuuk 3900, Greenland (Denmark); Stern, Gary A.; Pućko, Monika [Centre for Earth Observation Science, University of Manitoba, Winnipeg, MB R3T 2N2 (Canada); Foster, Karen L. [Foster Environmental, Peterborough, ON K9J 8L2 (Canada); Macdonald, Robie W. [Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC V8L 4B2 (Canada); Fortier, Louis [Québec-Océan, Département de Biologie, Université Laval, Québec, QC G1V 0A6 (Canada)

    2016-05-01

    Zooplankton play a central role in marine food webs, dictating the quantity and quality of energy available to upper trophic levels. They act as “keystone” species in transfer of mercury (Hg) up through the marine food chain. Here, we present the first Pan-Arctic overview of total and monomethylmercury concentrations (THg and MMHg) and stable isotope ratios of carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) in selected zooplankton species by assembling data collected between 1998 and 2012 from six arctic regions (Laptev Sea, Chukchi Sea, southeastern Beaufort Sea, Canadian Arctic Archipelago, Hudson Bay and northern Baffin Bay). MMHg concentrations in Calanus spp., Themisto spp. and Paraeuchaeta spp. were found to increase with higher δ{sup 15}N and lower δ{sup 13}C. The southern Beaufort Sea exhibited both the highest THg and MMHg concentrations. Biomagnification of MMHg between Calanus spp. and two of its known predators, Themisto spp. and Paraeuchaeta spp., was greatest in the southern Beaufort Sea. Our results show large geographical variations in Hg concentrations and isotopic signatures for individual species related to regional ecosystem features, such as varying water masses and freshwater inputs, and highlight the increased exposure to Hg in the marine food chain of the southern Beaufort Sea. - Highlights: • Assessment of Pan-Arctic variability in zooplankton Hg concentrations • Increased exposure to Hg in the marine food chain of the southern Beaufort Sea • Zooplankton plays a central role in the Hg pathway within Arctic marine food webs.

  20. Biogeochemical Indicators in High- and Low-Arctic Marine and Terrestrial Avian Community Changes: Comparative Isotopic (13C, 15N, and 34S) Studies in Alaska and Greenland

    Science.gov (United States)

    Causey, D.; Bargmann, N. A.; Burnham, K. K.; Burnham, J. L.; Padula, V. M.; Johnson, J. A.; Welker, J. M.

    2011-12-01

    Understanding the complex dynamics of environmental change in northern latitudes is of paramount importance today, given documented rapid shifts in sea ice, plant phenology, temperatures, deglaciation, and habitat fidelity. This knowledge is particularly critical for Arctic avian communities, which are integral components by which biological teleconnections are maintained between the mid and northern latitudes. Furthermore, Arctic birds are fundamental to Native subsistence lifestyles and a focus for conservation activities. Avian communities of marine and terrestrial Arctic environments represent a broad spectrum of trophic levels, from herbivores (eg., geese Chen spp.), planktivores (eg., auklets Aethia spp.), and insectivores (eg., passerines: Wheatears Oenanthe spp., Longspurs Calcarius spp.), to predators of marine invertebrates (eg., eiders Somateria spp.), nearshore and offshore fish (eg., cormorants Phalacrocorax spp, puffins Fratercula spp.), even other bird species (eg., gulls Larus spp., falcons Peregrinus spp.). This diversity of trophic interconnections is an integral factor in the dynamics of Arctic ecosystem ecology, and they are key indicators for the strength and trajectories of change. We are especially interested in their feeding ecology, using stable isotope-diet relations to examine historical diets and to predict future feeding ecology by this range of species. Since 2009, we have been studying the foodweb ecology using stable isotopes (δ13C, δ15N, δ34S) of contemporaneous coastal and marine bird communities in High Arctic (Northwest Greenland) and Low Arctic (western Aleutian Islands, AK). We are quantifying the isotopic values of blood, organ tissues, and feathers, and have carried out comparisons between native and lipid-extracted samples. Although geographically distant, these communities comprise similar taxonomic and ecological congeners, including several species common to both (eg., Common Eider, Black-legged Kittiwake, Northern

  1. 1H and 15N NMR resonance assignments and secondary structure of titin type I domains

    Energy Technology Data Exchange (ETDEWEB)

    Muhle-Goll, Claudia; Nilges, Michael; Pastore, Annalisa [European Molecular Biology Laboratory (Germany)

    1997-01-15

    Titin/connect in is a giant muscle protein with a highly modular architecture consisting of multiple repeats of two sequence motifs, named type I and type II. Type I modules have been suggested to be intracellular members of the fibronectin type III (Fn3) domain family. Along the titin sequence they are exclusively present in the region of the molecule located in the sarcomere A-band. This region has been shown to interact with myosin and C-protein. One of the most noticeable features of type I modules is that they are particularly rich in semiconserved prolines, since these residues account for about 8% of their sequence. We have determined the secondary structure of a representative type I domain (A71) by 15N and 1HNMR. We show that the type I domains of titin have the Fn3 fold as proposed, consisting of a three- and a four-stranded {beta}-sheet. When the two sheets are placed on top of each other to form the {beta}-sandwich characteristic of the Fn3 fold, 8 out of 10 prolines are found on the same side of the molecule and form an exposed hydrophobic patch. This suggests that the semiconserved prolines might be relevant for the function of type I modules, providing a surface for binding to other A-band proteins. The secondary structure of A71 was structurally aligned to other extracellular Fn3 modules of known 3D structure. The alignment shows that titin type I modules have closest similarity to the first Fn3 domain of Drosophila neuroglian.

  2. {sup 15}N/{sup 14}N isotopic ratio and statistical analysis: an efficient way of linking seized Ecstasy tablets

    Energy Technology Data Exchange (ETDEWEB)

    Palhol, Fabien; Lamoureux, Catherine; Chabrillat, Martine; Naulet, Norbert

    2004-05-10

    In this study, the {sup 15}N/{sup 14}N isotopic ratios of 106 samples of 3,4-methylenedioxymethamphetamine (MDMA) extracted from Ecstasy tablets are presented. These ratios, measured using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), show a large discrimination between samples with a range of {delta}{sup 15}N values between -17 and +19%o, depending on the precursors and the method used in clandestine laboratories. Thus, {delta}{sup 15}N values can be used in a statistical analysis carried out in order to link Ecstasy tablets prepared with the same precursors and synthetic pathway. The similarity index obtained after principal component analysis and hierarchical cluster analysis appears to be an efficient way to group tablets seized in different places.

  3. Diet-tissue stable isotope (Δ(13)C and Δ(15)N) discrimination factors for multiple tissues from terrestrial reptiles.

    Science.gov (United States)

    Steinitz, Ronnie; Lemm, Jeffrey M; Pasachnik, Stesha A; Kurle, Carolyn M

    2016-01-15

    Stable isotope analysis is a powerful tool for reconstructing trophic interactions to better understand drivers of community ecology. Taxon-specific stable isotope discrimination factors contribute to the best use of this tool. We determined the first Δ(13)C and Δ(15)N values for Rock Iguanas (Cyclura spp.) to better understand isotopic fractionation and estimate wild reptile foraging ecology. The Δ(13)C and Δ(15)N values between diet and skin, blood, and scat were determined from juvenile and adult iguanas held for 1 year on a known diet. We measured relationships between iguana discrimination factors and size/age and quantified effects of lipid extraction and acid treatment on stable isotope values from iguana tissues. Isotopic and elemental compositions were determined by Dumas combustion using an elemental analyzer coupled to an isotope ratio mass spectrometer using standards of known composition. The Δ(13)C and Δ(15)N values ranged from -2.5 to +6.5‰ and +2.2 to +7.5‰, respectively, with some differences among tissues and between juveniles and adults. The Δ(13)C values from blood and skin differed among species, but not the Δ(15)N values. The Δ(13)C values from blood and skin and Δ(15)N values from blood were positively correlated with size/age. The Δ(13)C values from scat were negatively correlated with size (not age). Treatment with HCl (scat) and lipid extraction (skin) did not affect the isotope values. These results should aid in the understanding of processes driving stable carbon and nitrogen isotope discrimination factors in reptiles. We provide estimates of Δ(13)C and Δ(15)N values and linear relationships between iguana size/age and discrimination factors for the best interpretation of wild reptile foraging ecology. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Earthworms and litter management contributions to ecosystem services in a tropical agroforestry system.

    Science.gov (United States)

    Fonte, Steven J; Six, Johan

    2010-06-01

    The development of sustainable agricultural systems depends in part upon improved management of non-crop species to enhance the overall functioning and provision of services by agroecosystems. To address this need, our research examined the role of earthworms and litter management on nutrient dynamics, soil organic matter (SOM) stabilization, and crop growth in the Quesungual agroforestry system of western Honduras. Field mesocosms were established with two earthworm treatments (0 vs. 8 Pontoscolex corethrurus individuals per mesocosm) and four litter quality treatments: (1) low-quality Zea mays, (2) high-quality Diphysa robinioides, (3) a mixture of low- and high-quality litters, and (4) a control with no organic residues applied. Mesocosms included a single Z. mays plant and additions of 15N-labeled inorganic nitrogen. At maize harvest, surface soils (0-15 cm) in the mesocosms were sampled to determine total and available P as well as the distribution of C, N, and 15N among different aggregate-associated SOM pools. Maize plants were divided into grain and non-grain components and analyzed for total P, N, and 15N. Earthworm additions improved soil structure as demonstrated by a 10% increase in mean weight diameter and higher C and N storage within large macro-aggregates (>2000 microm). A corresponding 17% increase in C contained in micro-aggregates within the macro-aggregates indicates that earthworms enhance the stabilization of SOM in these soils; however, this effect only occurred when organic residues were applied. Earthworms also decreased available P and total soil P, indicating that earthworms may facilitate the loss of labile P added to this system. Earthworms decreased the recovery of fertilizer-derived N in the soil but increased the uptake of 15N by maize by 7%. Litter treatments yielded minimal effects on soil properties and plant growth. Our results indicate that the application of litter inputs and proper management of earthworm populations can have

  5. Produção de amônia anidra e aquamônia enriquecida em 15N a partir de (15NH42SO4 Production of anhydrous ammonia and aqua ammonia enriched in 15N from (15NH42SO4

    Directory of Open Access Journals (Sweden)

    José Albertino Bendassolli

    2002-09-01

    Full Text Available No Brasil, a aquamônia vem sendo utilizada como fertilizante nitrogenado, especialmente na cultura de cana de açúcar. Entre os fatores que influenciam a produtividade das culturas agrícolas, está a eficiência de utilização de fertilizantes nitrogenados (EUF, sendo a técnica isotópica com 15N empregada em investigações dessa natureza. Este trabalho procurou estabelecer métodos de produção de amônia anidra (15NH3 e aquosa (15NH3aq, enriquecidas em 15N, em um único sistema, a partir do sulfato de amônio previamente enriquecido no mesmo isótopo. O processo de produção de 15NH3 e 15NH3aq foi avaliado em função dos fatores: temperatura (60, 70 e 75ºC e tempo de reação (90, 120, 150, 165, 210 e 255 minutos, fluxo de gás de arraste (140; 180 e 220 mL min-1 de N2 e massa de sulfato de amônio utilizada na reação (40; 72,6; 106; 132 e 200 g. As melhores condições com relação à produção de 15NH3 e 15NH3aq foram proporcionadas pela temperatura de 70ºC, fluxo de gás de arraste de 180 mL min-1 de N2 e tempo de reação de 210 minutos. O teor de N na 15NH3aq variou de 15 a 20% (m/m e o sistema apresentou capacidade de produção de aproximadamente 280 mL de 15NH3aq com concentração de 15% (m/m por batelada. O processo global apresentou rendimento na faixa de 91 a 99%, em função da massa de (15NH42SO4 utilizada, sendo as perdas de 15N desprezíveis.In Brazil aqua ammonia is an important fertilizer for soil fertilization of the sugarcane crop. The efficiency of the use of nitrogen fertilizers (EUF by crops is a factor that has influence on agricultural productivity. The isotope technique of 15N labeled fertilizer is used for EUF determinations. In this paper the methods for production, in a same system, of anhydrous ammonia (15NH3 and aqua ammonia (15NH3aq, both enriched in the heavy stable isotope of nitrogen, using ammonium sulfate (AS labeled with 15N [(15NH42SO4 ] as raw material, are presented. The parameters

  6. Utilização do nitrogênio (15N residual de coberturas de solo e da uréia pela cultura do milho Utilization of residual nitrogen (15N from cover crop and urea by corn

    Directory of Open Access Journals (Sweden)

    Edson Cabral da Silva

    2006-12-01

    study was to evaluate the use of residual nitrogen from urea, sunnhemp (Crotalaria juncea and millet (Pennisetum americanum labeled with 15N, applied to no-tillage corn in the previous growing season, in a Red Latosol of the Cerrado. The study was conducted in an experimental farm of the Sao Paulo State University (UNESP, Ilha Solteira, in Selvíria county (MS, Brazil, in different areas. The experiment had a randomized complete block design, with 15 treatments and four replications. Treatments were applied to corn crop in the 2001/02 and 2003/04 growing seasons. Theey were distributed in a 3 x 5 factorial layout, representing the combination of three cover crops: sunnhemp, millet and spontaneous vegetation (fallow and five N rates (as urea: 0, 30, 80, 130, and 180 kg ha-1 of N. After corn harvest, the two areas were fallowed in the dry season and were followed by corn crop in the 2002/03 (experiment 1 and 2003/04 (experiment 2 growing seasons, using the same fertilizer rate on all plots to distinguish the residual effect of N sources. The average use of residual N from the millet and sunnhemp residues (above-ground part by corn crop was less than 3.5 and 3 %, respectively, of the initial amount. The corn uptake of residual N from urea increased in a quadratic manner in experiment 1 and linearly in experiment Two as a response to the applied N rates, and the recover was below 3 %. The cover crop type did not affect the use of residual N of urea by corn, and vice-versa.

  7. Direct measurement of the 15N(p,gamma)16O total cross section at novae energies

    CERN Document Server

    Bemmerer, D; Bonetti, R; Broggini, C; Confortola, F; Corvisiero, P; Costantini, H; Elekes, Z; Formicola, A; Fülöp, Z; Gervino, G; Guglielmetti, A; Gustavino, C; Gyurky, Gy; Junker, M; Limata, B; Marta, M; Menegazzo, R; Prati, P; Roca, V; Rolfs, C; Alvarez, C Rossi; Somorjai, E; Straniero, O

    2009-01-01

    The 15N(p,gamma)16O reaction controls the passage of nucleosynthetic material from the first to the second carbon-nitrogen-oxygen (CNO) cycle. A direct measurement of the total 15N(p,gamma)16O cross section at energies corresponding to hydrogen burning in novae is presented here. Data have been taken at 90-230 keV center-of-mass energy using a windowless gas target filled with nitrogen of natural isotopic composition and a bismuth germanate summing detector. The cross section is found to be a factor two lower than previously believed.

  8. pH-induced changes in Rhodospirillum rubrum cytochrome c2 and subsequent renaturation: an 15N NMR study.

    OpenAIRE

    Yu,L.P.; Smith, G.M

    1988-01-01

    The 15N-enriched ferrocytochrome c2 from Rhodospirillum rubrum was studied by 15N NMR at different solvent pH values. The mobility and chemical shift of the N-terminal glutamic acid (335.4 ppm at pH 5.1) were found to depend on pH. It was least mobile between pH 8 and 9.0, which is explained in terms of pH-dependent conformational changes and formation of salt linkages and/or hydrogen bonds. The resonances of the lysine side chains are centered around 341.7 ppm at low pH and move upfield with...

  9. Recovery of {sup 15}N-urea in soil-plant system of tanzania grass pasture; Recuperacao de {sup 15}N-ureia no sistema solo-planta de pastagem de capim-Tanzania

    Energy Technology Data Exchange (ETDEWEB)

    Martha Junior, Geraldo Bueno; Vilela, Lourival [EMBRAPA Cerrados, Planaltina, DF (Brazil)], e-mail: gbmartha@cpac.embrapa.br; Corsi, Moacyr [Universidade de Sao Paulo (ESALQ/USP), Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz. Dept. de Zootecnica], e-mail: moa@esalq.usp.br; Trivelin, Paulo Cesar Ocheuze [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis], e-mail: pcotrive@cena.usp.br

    2009-01-15

    The economic attractiveness and negative environmental impact of nitrogen (N) fertilization in pastures depend on the N use efficiency in the soil-plant system. However, the recovery of urea-{sup 15}N by Panicum maximum cv. Tanzania pastures, one of the most widely used forage species in intensified pastoral systems, is still unknown. This experiment was conducted in a randomized complete block design with four treatments (0, 40, 80 and 120 kg ha-1 of N-urea) and three replications, to determine the recovery of {sup 15}N urea by Tanzania grass. Forage production, total N content and N yield were not affected by fertilization (p > 0.05), reflecting the high losses of applied N under the experimental conditions. The recovery of {sup 15}N urea (% of applied N) in forage and roots was not affected by fertilization levels (p > 0.05), but decreased exponentially in the soil and soil-plant system (p < 0.05) with increasing urea doses. The amount of {sup 15}N (kg ha{sup -1}) in forage and roots (15 to 30 cm) increased with increasing urea doses (p < 0.05). (author)

  10. MASS LOSS AND NITROGEN DYNAMICS DURING THE DECOMPOSITION OF A N-LABELED N2-FIXING EPOPHYTIC LICHEN, LOBARIA OREGANA (TUCK.) MULL. ARG.

    Science.gov (United States)

    We studied mass loss and nitrogen dynamics during fall and spring initiated decomposition of an N2-fixing epiphytic lichen, Lobaria oregana (Tuck.) Mull. Arg. using 15N. We developed a method of labeling lichens with 15N that involved spraying lichen material with a nutrient sol...

  11. Hyperpolarized 13 C,15 N2 -urea T2 relaxation changes in acute kidney injury

    DEFF Research Database (Denmark)

    Mariager, Christian Østergaard; Nielsen, Per Mose; Qi, Haiyun

    2017-01-01

    PURPOSE: To investigate the correlation between renal ischemia and 13 C-urea T2 relaxation rate in an acute kidney injury (AKI) rat model. METHODS: Six rats subjected to unilateral renal ischemia were investigated. Creatinine clearance, urine output, plasma creatinine as well as blood-urea nitrogen...... (BUN) values were acquired before and after the procedure. 1 H T2* mapping was acquired using blood oxygenation level dependent (BOLD) MRI and hyperpolarized 13 C-urea T2 mapping was acquired using a 2D golden-angle radial approach. Kidney perfusion was estimated using noncontrast flow alternating...... inversion recovery arterial spin labeling. RESULTS: All rats showed clinical signs of AKI with increased plasma creatinine and increased BUN. Whole kidney 13 C-urea T2 significantly decreased 26% (P = 0.001) 24 h after reperfusion. A significantly different (3.7 times steeper; P = 0.008) osmolality gradient...

  12. CARBON-RICH PRESOLAR GRAINS FROM MASSIVE STARS: SUBSOLAR {sup 12}C/{sup 13}C AND {sup 14}N/{sup 15}N RATIOS AND THE MYSTERY OF {sup 15}N

    Energy Technology Data Exchange (ETDEWEB)

    Pignatari, M. [Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Konkoly Thege Miklos ut 15-17, H-1121 Budapest (Hungary); Zinner, E. [Laboratory for Space Sciences and Physics Department, Washington University, St. Louis, MO 63130 (United States); Hoppe, P. [Max Planck Institute for Chemistry, D-55128 Mainz (Germany); Jordan, C. J.; Gibson, B. K. [E.A. Milne Centre for Astrophysics, Dept of Physics and Mathematics, University of Hull, HU6 7RX (United Kingdom); Trappitsch, R. [Department of the Geophysical Sciences and Chicago Center for Cosmochemistry, Chicago, IL 60637 (United States); Herwig, F. [Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P5C2 (Canada); Fryer, C. [Computational Physics and Methods (CCS-2), LANL, Los Alamos, NM, 87545 (United States); Hirschi, R. [Keele University, Keele, Staffordshire ST5 5BG (United Kingdom); Timmes, F. X. [The Joint Institute for Nuclear Astrophysics, Notre Dame, IN 46556 (United States)

    2015-08-01

    Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C and low-density (LD) graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing {sup 12}C/{sup 13}C and {sup 14}N/{sup 15}N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations are considered. If the supernova shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of {sup 13}C and {sup 15}N. The short-lived radionuclides {sup 22}Na and {sup 26}Al are increased by orders of magnitude. The production of radiogenic {sup 22}Ne from the decay of {sup 22}Na in the He shell might solve the puzzle of the Ne-E(L) component in LD graphite grains. This scenario is attractive for the SiC grains of type AB with {sup 14}N/{sup 15}N ratios lower than solar, and provides an alternative solution for SiC grains originally classified as nova grains. Finally, this process may contribute to the production of {sup 14}N and {sup 15}N in the Galaxy, helping to produce the {sup 14}N/{sup 15}N ratio in the solar system.

  13. Human baby hair amino acid natural abundance 15N-isotope values are not related to the 15N-isotope values of amino acids in mother's breast milk protein.

    Science.gov (United States)

    Romek, Katarzyna M; Julien, Maxime; Frasquet-Darrieux, Marine; Tea, Illa; Antheaume, Ingrid; Hankard, Régis; Robins, Richard J

    2013-12-01

    Since exclusively breast-suckled infants obtain their nutrient only from their mother's milk, it might be anticipated that a correlation will exist between the (15)N/(14)N isotope ratios of amino acids of protein of young infants and those supplied by their mother. The work presented here aimed to determine whether amino nitrogen transfer from human milk to infant hair protein synthesized within the first month of life conserves the maternal isotopic signature or whether post-ingestion fractionation dominates the nitrogen isotope spectrum. The study was conducted at 1 month post-birth on 100 mother-infant pairs. Isotope ratios (15)N/(14)N and (13)C/(12)C were measured using isotope ratio measurement by Mass Spectrometry (irm-MS) for whole maternal milk, and infant hair and (15)N/(14)N ratios were also measured by GC-irm-MS for the N-pivaloyl-O-isopropyl esters of amino acids obtained from the hydrolysis of milk and hair proteins. The δ(15)N and δ(13)C (‰) were found to be significantly higher in infant hair than in breast milk (δ(15)N, P amino acids in infant hair was also significantly higher than that in maternal milk (P < 0.001). By calculation, the observed shift in isotope ratio was shown not to be accounted for by the amino acid composition of hair and milk proteins, indicating that it is not simply due to differences in the composition in the proteins present. Rather, it would appear that each pool-mother and infant-turns over independently, and that fractionation in infant N-metabolism even in the first month of life dominates over the nutrient N-content.

  14. Impact of charring on cereal grain characteristics: linking prehistoric manuring practice to 15N signatures in archaeobotanical material

    DEFF Research Database (Denmark)

    Kanstrup, Marie; Thomsen, Ingrid Kaag; Mikkelsen, Peter Hambro

    2012-01-01

    Systematic use of animal manure has been demonstrated to be detectable in the plant δ15N value but evidence of manure affecting isotopic composition is mainly based on studies of fresh plant material. These findings can potentially be applied to archaeobotanical assemblages and thus provide infor...

  15. Natural abundance 15N in soil and litter across a nitrate-output gradient in New Hampshire

    Science.gov (United States)

    L.H. Pardo; H.F. Hemond; J.P. Montoya; J. Pett-Ridge

    2007-01-01

    Stable isotopes of nitrogen are potentially a valuable tool for regional assessments of nitrogen saturation because they provide an integrated measure of the past nitrogen cycling history of a site. We measured δ15N of soil and litter, as well as net nitrification potential, at three sites across a nitrate-loss gradient in the White...

  16. 1H, 13C and 15N NMR assignments of a calcium-binding protein from Entamoeba histolytica.

    Science.gov (United States)

    Verma, Deepshikha; Bhattacharya, Alok; Chary, Kandala V R

    2016-04-01

    We report almost complete sequence specific (1)H, (13)C and (15)N NMR assignments of a 150-residue long calmodulin-like calcium-binding protein from Entamoeba histolytica (EhCaBP6), as a prelude to its structural and functional characterization.

  17. Sequence specific 1H, 13C and 15N resonance assignments of hahellin in 8 M urea.

    Science.gov (United States)

    Srivastava, Atul K; Chary, K V R

    2010-10-01

    The sequence specific (1)H, (13)C and (15)N resonance assignments of hahellin in 8 M urea-denatured state have been accomplished by NMR spectroscopy. Secondary chemical shift analysis reveals the native-like propensities for β-rich conformation in the denatured state.

  18. Analysis of 15N incorporation into D-alanine: a new method for tracing nitrogen uptake by bacteria

    NARCIS (Netherlands)

    Veuger, B.; Middelburg, J.J.; Boschker, H.T.S.; Houtekamer, M.J.

    2005-01-01

    The quantitative contribution of bacteria to total microbial uptake of nitrogenous substrates is an aspect of the aquatic nitrogen cycle that is still largely unclear, mainly because existing methods are generally inadequate. We investigated the feasibility of measuring 15N incorporation into

  19. Variation in hair δ13C and δ15N values in long-tailed macaques (Macaca fascicularis) from Singapore

    Science.gov (United States)

    Schillaci, Michael A.; Castellini, J. Margaret; Stricker, Craig A.; Jones-Engel, Lisa; Lee, Benjamin P.Y.-H.

    2014-01-01

    Much of the primatology literature on stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) has focused on African and New World species, with comparatively little research published on Asian primates. Here we present hair δ13C and δ15N isotope values for a sample of 33 long-tailed macaques from Singapore. We evaluate the suggestion by a previous researcher that forest degradation and biodiversity loss in Singapore have led to a decline in macaque trophic level. The results of our analysis indicated significant spatial variability in δ13C but not δ15N. The range of variation in δ13C was consistent with a diet based on C3 resources, with one group exhibiting low values consistent with a closed canopy environment. Relative to other macaque species from Europe and Asia, the macaques from Singapore exhibited a low mean δ13C value but mid-range mean δ15N value. Previous research suggesting a decline in macaque trophic level is not supported by the results of our study.

  20. Proton-decoupled CPMG: a better experiment for measuring (15)N R2 relaxation in disordered proteins.

    Science.gov (United States)

    Yuwen, Tairan; Skrynnikov, Nikolai R

    2014-04-01

    (15)N R2 relaxation is one of the most informative experiments for characterization of intrinsically disordered proteins (IDPs). Small changes in nitrogen R2 rates are often used to determine how IDPs respond to various biologically relevant perturbations such as point mutations, posttranslational modifications and weak ligand interactions. However collecting high-quality (15)N relaxation data can be difficult. Of necessity, the samples of IDPs are often prepared with low protein concentration and the measurement time can be limited because of rapid sample degradation. Furthermore, due to hardware limitations standard experiments such as (15)N spin-lock and CPMG can sample the relaxation decay only to ca. 150ms. This is much shorter than (15)N T2 times in disordered proteins at or near physiological temperature. As a result, the sampling of relaxation decay profiles in these experiments is suboptimal, which further lowers the precision of the measurements. Here we report a new implementation of the proton-decoupled (PD) CPMG experiment which allows one to sample (15)N R2 relaxation decay up to ca. 0.5-1s. The new experiment has been validated through comparison with the well-established spin-lock measurement. Using dilute samples of denatured ubiquitin, we have demonstrated that PD-CPMG produces up to 3-fold improvement in the precision of the data. It is expected that for intrinsically disordered proteins the gains may be even more substantial. We have also shown that this sequence has a number of favorable properties: (i) the spectra are recorded with narrow linewidth in nitrogen dimension; (ii) (15)N offset correction is small and easy to calculate; (iii) the experiment is immune to various spurious effects arising from solvent exchange; (iv) the results are stable with respect to pulse miscalibration and rf field inhomogeneity; (v) with minimal change, the pulse sequence can also be used to measure R2 relaxation of (15)N(ε) spins in arginine side chains. We

  1. Stable isotope tracking of endangered sea turtles: validation with satellite telemetry and δ15N analysis of amino acids.

    Directory of Open Access Journals (Sweden)

    Jeffrey A Seminoff

    Full Text Available Effective conservation strategies for highly migratory species must incorporate information about long-distance movements and locations of high-use foraging areas. However, the inherent challenges of directly monitoring these factors call for creative research approaches and innovative application of existing tools. Highly migratory marine species, such as marine turtles, regularly travel hundreds or thousands of kilometers between breeding and feeding areas, but identification of migratory routes and habitat use patterns remains elusive. Here we use satellite telemetry in combination with compound-specific isotope analysis of amino acids to confirm that insights from bulk tissue stable isotope analysis can reveal divergent migratory strategies and within-population segregation of foraging groups of critically endangered leatherback sea turtles (Dermochelys coriacea across the Pacific Ocean. Among the 78 turtles studied, we found a distinct dichotomy in δ(15N values of bulk skin, with distinct "low δ(15N" and "high δ(15N" groups. δ(15N analysis of amino acids confirmed that this disparity resulted from isotopic differences at the base of the food chain and not from differences in trophic position between the two groups. Satellite tracking of 13 individuals indicated that their bulk skin δ(15N value was linked to the particular foraging region of each turtle. These findings confirm that prevailing marine isoscapes of foraging areas can be reflected in the isotopic compositions of marine turtle body tissues sampled at nesting beaches. We use a Bayesian mixture model to show that between 82 and 100% of the 78 skin-sampled turtles could be assigned with confidence to either the eastern Pacific or western Pacific, with 33 to 66% of all turtles foraging in the eastern Pacific. Our forensic approach validates the use of stable isotopes to depict leatherback turtle movements over broad spatial ranges and is timely for establishing wise conservation

  2. Retrospective characterization of ontogenetic shifts in killer whale diets via δ13C and δ15N analysis of teeth

    Science.gov (United States)

    Newsome, Seth D.; Etnier, Michael A.; Monson, Daniel H.; Fogel, Marilyn L.

    2009-01-01

    Metabolically inert, accretionary structures such as the dentin growth layers in teeth provide a life history record of individual diet with near-annual resolution. We constructed ontogenetic δ13C and δ15N profiles by analyzing tooth dentin growth layers from 13 individual killer whales Orcinus orca collected in the eastern northeast Pacific Ocean between 1961 and 2003. The individuals sampled were 6 to 52 yr old, representing 2 ecotypes—resident and transient—collected across ~25° of latitude. The average isotopic values of transient individuals (n = 10) are consistent with a reliance on mammalian prey, while the average isotopic values of residents (n = 3) are consistent with piscivory. Regardless of ecotype, most individuals show a decrease in δ15N values of ~2.5‰ through the first 3 yr of life, roughly equivalent to a decrease of one trophic level. We interpret this as evidence of gradual weaning, after which, ontogenetic shifts in isotopic values are highly variable. A few individuals (n = 2) maintained relatively stable δ15N and δ13C values throughout the remainder of their lives, whereas δ15N values of most (n = 11) increased by ~1.5‰, suggestive of an ontogenetic increase in trophic level. Significant differences in mean δ13C and δ15N values among transients collected off California suggest that individuality in prey preferences may be prevalent within this ecotype. Our approach provides retrospective individual life history and dietary information that cannot be obtained through traditional field observations of free-ranging and elusive species such as killer whales, including unique historic ecological information that pre-dates modern studies. By providing insights into individual diet composition, stable isotope analysis of teeth and/or bones may be the only means of evaluating a number of hypothesized historical dietary shifts in killer whales of the northeast Pacific Ocean

  3. Major Sources of Organic Matter in a Complex Coral Reef Lagoon: Identification from Isotopic Signatures (δ13C and δ15N.

    Directory of Open Access Journals (Sweden)

    Marine J Briand

    Full Text Available A wide investigation was conducted into the main organic matter (OM sources supporting coral reef trophic networks in the lagoon of New Caledonia. Sampling included different reef locations (fringing, intermediate and barrier reef, different associated ecosystems (mangroves and seagrass beds and rivers. In total, 30 taxa of macrophytes, plus pools of particulate and sedimentary OM (POM and SOM were sampled. Isotopic signatures (C and N of each OM sources was characterized and the composition of OM pools assessed. In addition, spatial and seasonal variations of reef OM sources were examined. Mangroves isotopic signatures were the most C-depleted (-30.17 ± 0.41 ‰ and seagrass signatures were the most C-enriched (-4.36 ± 0.72 ‰. Trichodesmium spp. had the most N-depleted signatures (-0.14 ± 0.03 ‰ whereas mangroves had the most N-enriched signatures (6.47 ± 0.41 ‰. The composition of POM and SOM varied along a coast-to-barrier reef gradient. River POM and marine POM contributed equally to coastal POM, whereas marine POM represented 90% of the POM on barrier reefs, compared to 10% river POM. The relative importance of river POM, marine POM and mangroves to the SOM pool decreased from fringing to barrier reefs. Conversely, the relative importance of seagrass, Trichodesmium spp. and macroalgae increased along this gradient. Overall, spatial fluctuations in POM and SOM were much greater than in primary producers. Seasonal fluctuations were low for all OM sources. Our results demonstrated that a large variety of OM sources sustain coral reefs, varying in their origin, composition and role and suggest that δ13C was a more useful fingerprint than δ15N in this endeavour. This study also suggested substantial OM exchanges and trophic connections between coral reefs and surrounding ecosystems. Finally, the importance of accounting for environmental characteristics at small temporal and spatial scales before drawing general patterns is

  4. Food Label and You

    Medline Plus

    Full Text Available ... Produced by CDRH-TV for CFSAN. back to menu More in Labeling & Nutrition Label Claims Front-of-Package Labeling Initiative Nutrition Facts Label Programs and Materials Nutrition Labeling Information for Restaurants & Retail Establishments Page Last Updated: 05/22/2016 ...

  5. Food Label and You

    Medline Plus

    Full Text Available ... Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food Label and You — Video Share Tweet Linkedin ...

  6. Food Label and You

    Medline Plus

    Full Text Available ... Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food Label and You Video Share Tweet Linkedin Pin ...

  7. Food Label and You

    Medline Plus

    Full Text Available ... Package Labeling Initiative Nutrition Facts Label Programs and Materials Nutrition Labeling Information for Restaurants & Retail Establishments Page ... State & Local Officials Consumers Health Professionals Science & Research Industry Scroll back to top Popular Content Home Latest ...

  8. Use of 15N labeled Urea to Study Nitrogen Use Efficiencies in a Forage Corn-Oat Rotation Grown on Clay and Sandy Clay Loam Soils of Mexico

    Science.gov (United States)

    Nitrogen (N) is applied in large amounts to sustain high forage yield and quality to feed a dairy cattle population surpassing 440,000 heads in Comarca Lagunera, Mexico (25° 32´ N, 103° 14´W and 1150 masl). Traditional farm practices across this region overaplly organic (manure) and fertilizer N. We...

  9. Expression and purification of 15N- and 13C-isotope labeled 40-residue human Alzheimer’s β-amyloid peptide for NMR-based structural analysis

    OpenAIRE

    Long, Fei; Cho, Wonhwa; Ishii, Yoshitaka

    2011-01-01

    Amyloid fibrils of Alzheimer’s β-amyloid peptide (Aβ) are a primary component of amyloid plaques, a hallmark of Alzheimer’s disease (AD). Enormous attention has been given to the structural features and functions of Aβ in amyloid fibrils and other type of aggregates in associated with development of AD. This report describes an efficient protocol to express and purify high-quality 40-residue Aβ(1–40), the most abundant Aβ in brains, for structural studies by NMR spectroscopy. Over-expression ...

  10. Simple approach for the preparation of 15-15N2-enriched water for nitrogen fixation assessments: Evaluation, application and recommendations

    Directory of Open Access Journals (Sweden)

    Isabell eKlawonn

    2015-08-01

    Full Text Available Recent findings revealed that the commonly used 15N2 tracer assay for the determination of dinitrogen (N2 fixation can underestimate the activity of aquatic N2-fixing organisms. Therefore, a modification to the method using pre-prepared 15-15N2-enriched water was proposed. Here, we present a rigorous assessment and outline a simple procedure for the preparation of 15-15N2-enriched water. We recommend to fill sterile-filtered water into serum bottles and to add 15-15N2 gas to the water in amounts exceeding the standard N2 solubility, followed by vigorous agitation (vortex mixing ≥5 min. Optionally, water can be degassed at low-pressure (≥950 mbar for ten minutes prior to the 15-15N2 gas addition to indirectly facilitate the 15-15N2 dissolution. This preparation of 15-15N2-enriched water can be done within one hour using standard laboratory equipment. The final 15N-atom% excess was 5% after replacing 2–5% of the incubation volume with 15-15N2-enriched water. Notably, the addition of 15-15N2-enriched water can alter levels of trace elements in the incubation water due to the contact of 15-15N2-enriched water with glass, plastic and rubber ware during its preparation. In our tests, levels of trace elements (Fe, P, Mn, Mo, Cu, Zn increased by up to 0.1 nmol L-1 in the final incubation volume, which may bias rate measurements in regions where N2 fixation is limited by trace elements. For these regions, we tested an alternative way to enrich water with 15-15N2. The 15-15N2 was injected as a bubble directly to the incubation water, followed by gentle shaking. Immediately thereafter, the bubble was replaced with water to stop the 15-15N2 equilibration. This method achieved a 15N-atom excess of 6.6±1.7% when adding 2 mL 15-15N2 per liter of incubation water. The herein presented methodological tests offer guidelines for the 15N2 tracer assay and thus, are crucial to circumvent methodological draw-backs for future N2 fixation assessments.

  11. Food Label and You

    Medline Plus

    Full Text Available ... Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition ...

  12. Identification of active metabolism roots of sugarcane for the isotopic dilution technique with {sup 15}N; Identificacao de raizes metabolicamente ativas de cana-de-acucar pela tecnica da diluicao isotopica com {sup 15}N

    Energy Technology Data Exchange (ETDEWEB)

    Faroni, Carlos E.; Bologna, Isabela R.; Franco, Henrique C.J. [Sao Paulo Univ., Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz. Dept. de Solos e Nutricao de Plantas]. E-mail: cfaroni@cena.usp.br; irbologn@esalq.usp.br; hjfranco@cena.usp.br; Trivelin, Paulo C.O.; Vitti, Andre C. [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Isotopos Estaveis]. E-mail: pcotrive@cena.usp.br; acvitti@cena.usp.br

    2005-07-01

    The knowledge of the sugarcane roots growth dynamics, as well as of the root system architecture of its, better allows to understanding of the relations between the plant and its environment of production, making possible the handling from practical more efficient and sustainable agriculturists who result in increase of productivity and longevity of the culture. In the study of the development of the sugarcane root system has an aggravating one in what the root renewal between cycles is mentioned to it, or in the same cycle, becoming necessary the identification of alive or active metabolism roots in a total mass showed. The present study it had for objective to develop a methodology of sugarcane active metabolism roots identification in the ground, by means of the isotopic dilution technique with {sup 15}N. The sugarcane root system study it can be carried through with this isotopic marker saw leaf application, a time that {sup 15}N is translocated until the root system. The experiment was carried through in commercial area of sugarcane in the region of Piracicaba, State of Sao Paulo, in a Oxissoil, with one second sprouts again of cultivating RB85 5156. The urea was the vehicle of supply of the isotopic marker {sup 15}N, by means of solution applied to leaves of the plants. After harvest of the aerial part, carried through 96 hours after the application of the urea solution, had been opened trenches, transversally to the line of the culture, with dimensions of 1 m of length and 1,4 m of width. The ground samples had been harvested by means of monoliths (5,6 dm{sup -3}) in the depths of 0-20, 20-40, 40-60 and 60-80 cm, in the projection of the line of the culture and laterally in the distances of 14-42 cm and 42-70 cm of the culture line. In each depth of sampling, and the culture line projection, they had been separate samples of visually active roots. These samples had been considered standard for the determination for isotopic dilution technique of roots with

  13. Uptake and distribution of /sup 15/N enriched nitrate by three rootstock cultivars grafted to Chenin blanc

    Energy Technology Data Exchange (ETDEWEB)

    Conradie, W.J. (Viticultural and Oenological Research Inst. Stellenbosch, South Africa)

    1983-01-01

    The uptake and distribution of nitrogen by the rootstocks 99R,101-14 Mgt and 140 Ruggeri grafted to Chenin blanc in sand culture, were determined using /sup 15/N enriched potassium nitrate. The K/sup 15/NO/sub 3/ was applied at the end of rapid shoot growth and the vines were sampled at veraison. Although vines grafted on 99R showed less aerial- and root growth than those on 101-14Mgt and 140 Ruggeri, nitrogen was absorbed equally well by all three rootstocks. The distribution of newly absorbed nitrogen could be accurately determined by means of /sup 15/N, and at veraison more than half of newly absorbed N was found in the leaves and shoots, and about 15% in the bunches. It was clear that nitrogen which accumulated in the bunches during the period of investigation, was derived primarily from previously assimilated N in the roots and mature wood.

  14. O potencial da rotulação metabólica de 15N para a pesquisa de esquizofrenia

    Directory of Open Access Journals (Sweden)

    Michaela D. Filiou

    2013-01-01

    Full Text Available Pesquisas em psiquiatria ainda necessitam de estudos não dirigidos por hipóteses para revelar fundamentos neurobiológicos e biomarcadores moleculares para distúrbios psiquiátricos. Metodologias proteômicas disponibilizam uma série de ferramentas para esses fins. Apresentamos o princípio de rotulação metabólica utilizando 15N para proteômica quantitativa e suas aplicações em modelos animais de fenótipos psiquiátricos com um foco particular em esquizofrenia. Exploramos o potencial de rotulação metabólica por 15N em diferentes tipos de experimentos, bem como suas considerações metodológicas.

  15. Facile measurement of {sup 1}H-{sup 15}N residual dipolar couplings in larger perdeuterated proteins

    Energy Technology Data Exchange (ETDEWEB)

    Fitzkee, Nicholas C.; Bax, Ad, E-mail: bax@nih.go [National Institutes of Health, Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases (United States)

    2010-10-15

    We present a simple method, ARTSY, for extracting {sup 1}J{sub NH} couplings and {sup 1}H-{sup 15}N RDCs from an interleaved set of two-dimensional {sup 1}H-{sup 15}N TROSY-HSQC spectra, based on the principle of quantitative J correlation. The primary advantage of the ARTSY method over other methods is the ability to measure couplings without scaling peak positions or altering the narrow line widths characteristic of TROSY spectra. Accuracy of the method is demonstrated for the model system GB3. Application to the catalytic core domain of HIV integrase, a 36 kDa homodimer with unfavorable spectral characteristics, demonstrates its practical utility. Precision of the RDC measurement is limited by the signal-to-noise ratio, S/N, achievable in the 2D TROSY-HSQC spectrum, and is approximately given by 30/(S/N) Hz.

  16. Effect of four plant species on soil 15N-access and herbage yield in temporary agricultural grasslands

    DEFF Research Database (Denmark)

    Pirhofer-Walzl, Karin; Eriksen, J.; Rasmussen, Jesper

    2013-01-01

    Abstract Background and aims We carried out field experiments to investigate if an agricultural grassland mixture comprising shallow- (perennial ryegrass: Lolium perenne L.; white clover: Trifolium repens L.) and deep- (chicory: Cichorium intybus L.; Lucerne: Medicago sativa L.) rooting grassland...... species has greater herbage yields than a shallow-rooting two-species mixture and pure stands, if deep-rooting grassland species are superior in accessing soil 15N from 1.2 m soil depth compared with shallow-rooting plant species and vice versa, if a mixture of deep- and shallow-rooting plant species has......-access of pure stands, two-species and four-species grassland communities. Results Herbage yield and soil 15N-access of the mixture including deep- and shallow-rooting grassland species were generally greater than the pure stands and the two-species mixture, except for herbage yield in pure stand lucerne...

  17. Cross relaxation in nitroxide spin labels

    DEFF Research Database (Denmark)

    Marsh, Derek

    2016-01-01

    Cross relaxation, and mI-dependence of the intrinsic electron spin-lattice relaxation rate We, are incorporated explicitly into the rate equations for the electron-spin population differences that govern the saturation behaviour of 14N- and 15N-nitroxide spin labels. Both prove important in spin......-label EPR and ELDOR, particularly for saturation recovery studies. Neither for saturation recovery, nor for CW-saturation EPR and CW-ELDOR, can cross relaxation be described simply by increasing the value of We, the intrinsic spin-lattice relaxation rate. Independence of the saturation recovery rates from...... the hyperfine line pumped or observed follows directly from solution of the rate equations including cross relaxation, even when the intrinsic spin-lattice relaxation rate We is mI-dependent....

  18. Fate of 15N-urea applied to wheat-soybean succession crop Destino de 15N-uréia aplicada em sucessão trigo-soja

    Directory of Open Access Journals (Sweden)

    Antonio Enedi Boaretto

    2004-01-01

    Full Text Available The wheat crop in São Paulo State, Brazil, is fertilized with N, P and K. The rate of applied N (0 to 120 kg.ha-1 depends on the previous grown crop and the irrigation possibility. The response of wheat to rates and time of N application and the fate of N applied to irrigated wheat were studied during two years. Residual N recovery by soybean grown after the wheat was also studied. The maximum grain productivity was obtained with 92 kg.ha-1 of N. The efficiency of 15N-urea utilization ranged from 52% to 85%. The main loss of applied 15N, 5% to 12% occurred as ammonia volatilized from urea applied on soil surface. The N loss by leaching even at the N rate of 135 kg.ha-1, was less than 1% of applied 15N, due to the low amount of rainfall during the wheat grown season and a controlled amount of irrigated water, that were sufficient to moisten only the wheat root zone. The residual 15N after wheat harvest represents around 40% of N applied as urea: 20% in soil, 3% in wheat root system and 16% in the wheat straw. Soybean recovered less than 2% of the 15N applied to wheat at sowing or at tillering stage.No Estado de São Paulo, a cultura do trigo é adubada, além de P e K, com N, cuja dose (0 a 120 kg ha-1 depende do cultivo anterior e da possibilidade de irrigação. A resposta do trigo às doses e épocas de aplicação e o destino do N aplicado foi estudada em dois cultivos de trigo, seguidos pela soja. Também se avaliou a recuperação do N residual pela soja cultivada nas mesmas parcelas após o trigo. A produtividade máxima estimada de grãos seria obtida com a dose de 92 kg.ha-1 de N. A eficiência de absorção 15N-uréia variou de 52% a 85%. A principal perda de N, que variou de 5% a 12%, ocorreu através de volatilização de amônia proveniente da uréia aplicada na superfície do solo. Por lixiviação foi perdido menos que 1% do N aplicado, pois a água da chuva ou da irrigação foi suficiente para molhar somente a camada do solo

  19. The effects of nitrogen pollutants on the isotopic signal (δ15N) of Ulva lactuca: Microcosm experiments.

    Science.gov (United States)

    Orlandi, Lucia; Calizza, Edoardo; Careddu, Giulio; Carlino, Pasquale; Costantini, Maria Letizia; Rossi, Loreto

    2017-02-15

    Effects of two chemical forms of Nitrogen (NH4+ and NO3-) on δ15N in Ulva lactuca were analysed separately and in mixture at two concentrations. We assessed whether the δ15N values of U. lactuca discriminate between Nitrogen from synthetic fertilisers (inorganic) and from fresh cow manure (organic), and the isotopic ability of the macroalga to reflect Nitrogen concentrations. Isotopic signature and N content of the macroalga reflected different nitrogenous sources and their concentrations after 48h. The inorganic Nitrogen source (NH4NO3) altered the isotopic values of the macroalgae more than Nitrogen from fresh cow manure (NO3-). δ15N values observed in the mixed solution did not differ from those displayed in NH4NO3 treatment alone. We conclude that stable isotope analysis of U. lactuca collected in an unpolluted site and experimentally submerged in sites suspected of being affected by disturbance is a useful tool for rapid monitoring of anthropogenic discharges of Nitrogen pollutants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Patterns of δ13C and δ15N in wolverine Gulo gulo tissues from the Brooks Range, Alaska

    Directory of Open Access Journals (Sweden)

    Fredrik DALERUM

    2009-06-01

    Full Text Available Knowledge of carnivore diets is essential to understand how carnivore populations respond demographically to variations in prey abundance. Analysis of stable isotopes is a useful complement to traditional methods of analyzing carnivore diets. We used data on d13C and d15N in wolverine tissues to investigate patterns of seasonal and annual diet variation in a wolverine Gulo gulo population in the western Brooks Range, Alaska, USA. The stable isotope ratios in wolverine tissues generally reflected that of terrestrial carnivores, corroborating previous diet studies on wolverines. We also found variation in d13C and d15N both between muscle samples collected over several years and between tissues with different assimilation rates, even after correcting for isotopic fractionation. This suggests both annual and seasonal diet variation. Our results indicate that data on d13C and d15N holds promise for qualitative assessments of wolverine diet changes over time. Such temporal variation may be important indicators of ecological responses to environmental perturbations, and we suggest that more refined studies of stable isotopes may be an important tool when studying temporal change in diets of wolverines and similar carnivores [Current Zoology 55(3: 188–192, 2009].

  1. Nitrogen release, tree uptake, and ecosystem retention in a mid-rotation loblolly pine plantation following fertilization with 15N-enriched enhanced efficiency fertilizers.

    OpenAIRE

    Werner, Amy

    2013-01-01

    Nitrogen is the most frequently limiting nutrient in southern pine plantations.  Previous studies found that only 10 to 25% of applied urea fertilizer N is taken up by trees.  Enhanced efficiency fertilizers could increase tree uptake efficiency by controlling the release of N and/or stabilize N.  Three enhanced efficiency fertilizers were selected as a representation of fertilizers that could be used in forestry: 1) NBPT treated urea (NBPT urea), 2) polymer coated urea (PC urea), and 3) mono...

  2. The natural abundance of 15N in litter and soil profiles under six temperate tree species: N cycling depends on tree species traits and site fertility

    DEFF Research Database (Denmark)

    Callesen, Ingeborg; Nilsson, Lars Ola; Schmidt, Inger Kappel

    2013-01-01

    European broadleaved tree species and Norway spruce.Litter δ15N and 15N enrichment factor (δ15Nlitter–δ15Nsoil) were positively correlated with N status based on soil and litter N pools, nitrification, subsoil nitrate concentration and forest growth. Tree species differences were also significant...... for these N variables and for the litter δ15N and enrichment factor. Litter from ash and sycamore maple with high N status and low fungal mycelia activity was enriched in 15N (+0.9 delta units) relative to other tree species (European beech, pedunculate oak, lime and Norway spruce) even though the latter...

  3. Mangrove isotopic (δ15N and δ13C) fractionation across a nitrogen vs. phosphorus limitation gradient

    Science.gov (United States)

    Mckee, Karen L.; Feller, Ilka C.; Popp, Marianne; Wanek, Wolfgang

    2002-01-01

    Mangrove islands in Belize are characterized by a unique switching from nitrogen (N) to phosphorus (P) limitation to tree growth from shoreline to interior. Fertilization has previously shown that Rhizophora mangle (red mangrove) fringe trees (5–6 m tall) growing along the shoreline are N limited; dwarf trees (!1.5 m tall) in the forestinterior are P limited; and transition trees (2–4 m tall) are co-limited by both N and P.  Growth patterns paralleled a landward decrease in soil flushing by tides and an increase in bioavailable N, but P availability remained consistently low across the gradient. Stable isotopic composition was measured in R. mangle leaves to aid in explaining this nutrient switching pattern and growth variation. Along control transects, leaf !15N decreased from "0.10‰ (fringe) to #5.38‰ (dwarf). The !15N of N-fertilized trees also varied spatially, but the values were consistently more negative (by $3‰) compared to control trees. Spatial variation in !15N values disappeared when the trees were fertilized with P, and values averaged "0.12‰, similar to that in control fringe trees. Neither variation in source inputs nor microbial fractionation could fully account for the observed patterns in !15N. The results instead suggest that the lower !15N values in transition and dwarf control trees were due to plant fractionation as a consequence of slower growth and lower N demand. P fertilization increased N demand and decreased fractionation. Although leaf !13C was unaffected by fertilization, values increased from fringe (#28.6‰) to transition (#27.9‰) to dwarf (#26.4‰) zones, indicating spatial variation in environmental stresses affecting stomatal conductance or carboxylation. The results thus suggest an interaction of external supply, internal demand, and plant ability to acquire nutrients under different hydro-edaphic conditions that vary across this tree-height gradient. The findings not only aid in understanding

  4. Industrial Robot Label Applicator

    OpenAIRE

    Kukasch, Kai

    2017-01-01

    The thesis deals with a project carried out for developing and setting up a robot label applicator system. The requirement was that RFID tracking labels can be applied on flexible positions, without manual effort and rearrangement, via programming. The purpose of the robot label applicator system is to increase the efficiency in production sites, where the RFID label position can change, depending on product or other reasons. New label positions should be programmed easily with a human-m...

  5. Nitrogen dynamics in oak model ecosystems subjected to air warming and drought on two different soils.

    Science.gov (United States)

    Kuster, T M; Schleppi, P; Hu, B; Schulin, R; Günthardt-Goerg, M S

    2013-01-01

    Being tolerant to heat and drought, oaks are promising candidates for future forestry in view of climate change in Central Europe. Air warming is expected to increase, and drought decrease soil N availability and thus N supply to trees. Here, we conducted a model ecosystem experiment, in which mixed stands of young oaks (Quercus robur, Q. petraea and Q. pubescens) were grown on two different soils and subjected to four climate treatments during three growing seasons: air warming by 1-2 °C, drought periods (average precipitation reduction of 43-60%), a combination of these two treatments, and a control. In contrast to our hypotheses, neither air warming nor drought significantly affected N availability, whereas total amounts, vertical distribution and availability of soil N showed substantial differences between the two soils. While air warming had no effect on tree growth and N accumulation, the drought treatment reduced tree growth and increased, or tended to increase, N accumulation in the reduced biomass, indicating that growth was not limited by N. Furthermore, (15) N-labelling revealed that this accumulation was associated with an increased uptake of nitrate. On the basis of our results, climate change effects on N dynamics are expected to be less important in oak stands than reduced soil water availability. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

  6. Net Ecosystem Carbon Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Net Ecosystem Carbon Flux is defined as the year-over-year change in Total Ecosystem Carbon Stock, or the net rate of carbon exchange between an ecosystem and the...

  7. Microbial Ecosystems, Protection of

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Nelson, K.E.

    2014-01-01

    Synonyms Conservation of microbial diversity and ecosystem functions provided by microbes; Preservation of microbial diversity and ecosystem functions provided by microbes Definition The use, management, and conservation of ecosystems in order to preserve microbial diversity and functioning.

  8. Astronomical Ecosystems

    Science.gov (United States)

    Neuenschwander, D. E.; Finkenbinder, L. R.

    2004-05-01

    Just as quetzals and jaguars require specific ecological habitats to survive, so too must planets occupy a tightly constrained astronomical habitat to support life as we know it. With this theme in mind we relate the transferable features of our elementary astronomy course, "The Astronomical Basis of Life on Earth." Over the last five years, in a team-taught course that features a spring break field trip to Costa Rica, we have introduced astronomy through "astronomical ecosystems," emphasizing astronomical constraints on the prospects for life on Earth. Life requires energy, chemical elements, and long timescales, and we emphasize how cosmological, astrophysical, and geological realities, through stabilities and catastrophes, create and eliminate niches for biological life. The linkage between astronomy and biology gets immediate and personal: for example, studies in solar energy production are followed by hikes in the forest to examine the light-gathering strategies of photosynthetic organisms; a lesson on tides is conducted while standing up to our necks in one on a Pacific beach. Further linkages between astronomy and the human timescale concerns of biological diversity, cultural diversity, and environmental sustainability are natural and direct. Our experience of teaching "astronomy as habitat" strongly influences our "Astronomy 101" course in Oklahoma as well. This "inverted astrobiology" seems to transform our student's outlook, from the universe being something "out there" into something "we're in!" We thank the SNU Science Alumni support group "The Catalysts," and the SNU Quetzal Education and Research Center, San Gerardo de Dota, Costa Rica, for their support.

  9. Determination of the delta(15N/14N)of Ammonium (NH4+) in Water: RSIL Lab Code 2898

    Science.gov (United States)

    Hannon, Janet E.; Böhlke, John Karl

    2008-01-01

    The purpose of the technique described by Reston Stable Isotope Laboratory (RSIL) lab code 2898 is to determine the N isotopic composition, delta(15N/14N), abbreviated as d15N, of ammonium (NH4+) in water (freshwater and saline water). The procedure involves converting dissolved NH4+ into NH3 gas by raising the pH of the sample to above 9 with MgO and subsequently trapping the gas quantitatively as (NH4)2SO4 on a glass fiber (GF) filter. The GF filter is saturated with NaHSO4 and pressure sealed between two gas-permeable polypropylene filters. The GF filter 'sandwich' floats on the surface of the water sample in a closed bottle. NH3 diffuses from the water through the polypropylene filter and reacts with NaHSO4, forming (NH4)2SO4 on the GF filter. The GF filter containing (NH4)2SO4 is dried and then combusted with a Carlo Erba NC 2500 elemental analyzer (EA), which is used to convert total nitrogen in a solid sample into N2 gas. The EA is connected to a continuous-flow isotope-ratio mass spectrometer (CF-IRMS), which determines the relative difference in ratios of the amounts of the stable isotopes of nitrogen (15N and 14N) of the product N2 gas and a reference N2 gas. The filters containing the samples are compressed in tin capsules and loaded into a Costech Zero-Blank Autosampler on the EA. Under computer control, samples then are dropped into a heated reaction tube that contains an oxidant, where combustion takes place in a He atmosphere containing an excess of O2 gas. To remove S-O gases produced from the NaHSO4, a plug of Ag-coated Cu wool is inserted at the bottom of the reaction tube. Combustion products are transported by a He carrier through a reduction furnace to remove excess O2, toconvert all nitrogen oxides to N2, and to remove any remaining S-O gases. The gases then pass through a drying tube to remove water. The gas-phase products, mainly N2 and a small amount of background CO2, are separated by a gas chromatograph (GC). The gas is then introduced

  10. Stable isotope analysis (δ13C and δ15N of soil nematodes from four feeding groups

    Directory of Open Access Journals (Sweden)

    Carol Melody

    2016-09-01

    Full Text Available Soil nematode feeding groups are a long-established trophic categorisation largely based on morphology and are used in ecological indices to monitor and analyse the biological state of soils. Stable isotope ratio analysis (13C/12C and 15N/14N, expressed as δ13C and δ15N has provided verification of, and novel insights into, the feeding ecology of soil animals such as earthworms and mites. However, isotopic studies of soil nematodes have been limited to date as conventional stable isotope ratio analysis needs impractically large numbers of nematodes (up to 1,000 to achieve required minimum sample weights (typically >100 µg C and N. Here, micro-sample near-conventional elemental analysis–isotopic ratio mass spectrometry (μEA–IRMS of C and N using microgram samples (typically 20 µg dry weight, was employed to compare the trophic position of selected soil nematode taxa from four feeding groups: predators (Anatonchus and Mononchus, bacterial feeders (Plectus and Rhabditis, omnivores (Aporcelaimidae and Qudsianematidae and plant feeder (Rotylenchus. Free-living nematodes were collected from conventionally and organically managed arable soils. As few as 15 nematodes, for omnivores and predators, were sufficient to reach the 20 µg dry weight target. There was no significant difference in δ15N (p = 0.290 or δ13C (p = 0.706 between conventional and organic agronomic treatments but, within treatments, there was a significant difference in N and C stable isotope ratios between the plant feeder, Rotylenchus (δ15N = 1.08 to 3.22 mUr‰, δ13C = –29.58 to –27.87 mUr and all other groups. There was an average difference of 9.62 mUr in δ15N between the plant feeder and the predator group (δ15N = 9.89 to 12.79 mUr, δ13C = –27.04 to –25.51 mUr. Isotopic niche widths were calculated as Bayesian derived standard ellipse areas and were smallest for the plant feeder (1.37 mUr2 and the predators (1.73 mUr2, but largest for omnivores (3.83 mUr2

  11. Natural (15)N Abundance in Key Amino Acids from Lamb Muscle: Exploring a New Horizon in Diet Authentication and Assessment of Feed Efficiency in Ruminants.

    Science.gov (United States)

    Cantalapiedra-Hijar, Gonzalo; Ortigues-Marty, Isabelle; Schiphorst, Anne-Marie; Robins, Richard J; Tea, Illa; Prache, Sophie

    2016-05-25

    Natural (15)N abundance (δ(15)N) varies between individual amino acids (AAs). We hypothesized that δ(15)N of nontransaminating and essential AAs ("source" AAs, such as phenylalanine) present in animal tissues could be used as a marker of dietary origin, whereas δ(15)N of transaminating AAs ("trophic" AAs, such as glutamic acid) could give more detailed insights into animal feed efficiency. Two diets based on dehydrated Lucerne pellets were tested in growing lambs, which promoted different feed efficiencies. No dietary effects were noted on δ(15)N of any AAs analyzed in lamb muscle. In addition, δ(15)N of phenylalanine was unexpectedly similar to that of glutamic acid, suggesting that δ(15)N of AAs is significantly derived from the metabolism of the rumen microbiota and, thus, are not suited for diet authentication in ruminants. In contrast, the δ(15)N of transaminating AAs facilitates an improved prediction of animal feed efficiency compared to the classical isotopic bulk N analysis.

  12. δ15N values of atmospheric N species simultaneously collected using sector-based samplers distant from sources - Isotopic inheritance and fractionation

    Science.gov (United States)

    Savard, Martine M.; Cole, Amanda; Smirnoff, Anna; Vet, Robert

    2017-08-01

    The nitrogen isotope ratios (δ15N) of atmospheric N species are commonly suggested as indicators of N emission sources. Therefore, numerous research studies have developed analytical methodologies and characterized primary (gases) and secondary emission products (mostly precipitation and aerosols) from various emitters. These previous studies have generally collected either reduced or oxidized N forms, and sampled them separately prior to determining their δ15N values. Distinctive isotopic signals have been reported for emissions from various sources, and seasonality of the δ15N values has been frequently attributed to shifts in relative contributions from sources with different isotopic signals. However, theoretical concepts suggest that temperature effects on isotopic fractionation may also affect the δ15N values of atmospheric reaction products. Here we use a sector-based multi-stage filter system to simultaneously collect seven reduced and oxidized N species downwind from five different source types in Alberta, Canada. We report δ15N values obtained with a state-of-the-art gold-furnace pre-concentrator online with an isotope ratio mass spectrometer (IRMS) to provide representative results even for oxidized-N forms. We find that equilibrium isotope effects and their temperature dependence play significant roles in determining the δ15N values of the secondary emission products. In the end, seasonal δ15N changes here are mainly caused by temperature effects on fractionation, and the δ15N values of only two N species from one source type can be retained as potential fingerprints of emissions.

  13. 15N Isotopic Crop Exchange Residue Studies Suggest that IPCC N Input Methodologies to Assess N2O-N Emissions Should be Reevaluated

    Science.gov (United States)

    It is difficult to quantify nitrogen (N) losses from agricultural systems to the environment, however we can use 15N isotopic techniques to conduct site specific studies to increase our knowledge about N management and fate. This manuscript synthesizes the review of two selected 15N isotopic studies...

  14. Revision of the 15N(p, γ)16O reaction rate and oxygen abundance in H-burning zones

    Science.gov (United States)

    Caciolli, A.; Mazzocchi, C.; Capogrosso, V.; Bemmerer, D.; Broggini, C.; Corvisiero, P.; Costantini, H.; Elekes, Z.; Formicola, A.; Fülöp, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, Gy.; Imbriani, G.; Junker, M.; Lemut, A.; Marta, M.; Menegazzo, R.; Palmerini, S.; Prati, P.; Roca, V.; Rolfs, C.; Rossi Alvarez, C.; Somorjai, E.; Straniero, O.; Strieder, F.; Terrasi, F.; Trautvetter, H. P.; Vomiero, A.

    2011-09-01

    Context. The NO cycle takes place in the deepest layer of a H-burning core or shell, when the temperature exceeds T ≃ 30 × 106 K. The O depletion observed in some globular cluster giant stars, always associated with a Na enhancement, may be due to either a deep mixing during the red giant branch (RGB) phase of the star or to the pollution of the primordial gas by an early population of massive asymptotic giant branch (AGB) stars, whose chemical composition was modified by the hot bottom burning. In both cases, the NO cycle is responsible for the O depletion. Aims: The activation of this cycle depends on the rate of the 15N(p, γ)16O reaction. A precise evaluation of this reaction rate at temperatures as low as experienced in H-burning zones in stellar interiors is mandatory to understand the observed O abundances. Methods: We present a new measurement of the 15N(p, γ)16O reaction performed at LUNA covering for the first time the center of mass energy range 70-370 keV, which corresponds to stellar temperatures between 65 × 106 K and 780 × 106 K. This range includes the 15N(p, γ)16O Gamow-peak energy of explosive H-burning taking place in the external layer of a nova and the one of the hot bottom burning (HBB) nucleosynthesis occurring in massive AGB stars. Results: With the present data, we are also able to confirm the result of the previous R-matrix extrapolation. In particular, in the temperature range of astrophysical interest, the new rate is about a factor of 2 smaller than reported in the widely adopted compilation of reaction rates (NACRE or CF88) and the uncertainty is now reduced down to the 10% level.

  15. Characterization of Nitrogen Uptake Pattern in Malaysian Rice MR219 at Different Growth Stages Using 15N Isotope

    Directory of Open Access Journals (Sweden)

    Mohammad Mu’az Hashim

    2015-09-01

    Full Text Available Nitrogen (N use efficiency is usually less than 50%, and it remains a major problem in rice cultivation. Controlled release fertilizer (CRF technology is one of the well-known efforts to overcome this problem. The efficiency of CRF, however, is very much dependent on the timing of nutrient release. This study was conducted to determine the precise time of N uptake by rice as a guideline to develop efficient CRF. Fertilizer N uptake by rice at different growth stages was investigated by using 15N isotopic technique. Rice was planted in pots, with 15N urea as N source at the rate of 120 kg/hm2. Potassium and phosphorus were applied at the same rate of 50 kg/hm2. Standard agronomic practices were employed throughout the growing periods. Rice plants were harvested every two weeks until maturation at the 14th week and analyzed for total N and 15N content. Nitrogen derived from fertilizer was calculated. Total N uptake in plants consistently increased until the 11th week. After that, it started to plateau and finally declined. Moreover, N utilization by rice plants peaked at 50%, which occurred during the 11th week after transplanting. N derived from fertilizer in rice plants were in the range of 18.7% to 40.0% in all plant tissues. The remaining N was derived from soil. Based on this study, N release from CRF should complete by the 11th week after planting to ensure the maximum fertilizer N uptake by rice plants. Efficient CRF should contribute to higher N derived from fertilizer which also resultedin a higher total N uptake by rice plants, increasing the potential of rice to produce higher yield while at the same time of reducing loss.

  16. Seasonal variation in nitrogen pools and 15N/13C natural abundances in different tissues of grassland plants

    Directory of Open Access Journals (Sweden)

    J. K. Schjoerring

    2012-05-01

    Full Text Available Seasonal changes in nitrogen (N pools, carbon (C content and natural abundance of 13C and 15N in different tissues of ryegrass plants were investigated in two intensively managed grassland fields in order to address their ammonia (NH3 exchange potential. Green leaves generally had the largest total N concentration followed by stems and inflorescences. Senescent leaves had the lowest N concentration, indicating N re-allocation. The seasonal pattern of the Γ value, i.e. the ratio between NH4+ and H+ concentrations, was similar for the various tissues of the ryegrass plants but the magnitude of Γ differed considerably among the different tissues. Green leaves and stems generally had substantially lower Γ values than senescent leaves and litter. Substantial peaks in Γ were observed during spring and summer in response to fertilization and grazing. These peaks were associated with high NH4+ rather than with low H+ concentrations. Peaks in Γ also appeared during the winter, coinciding with increasing δ15N values, indicating absorption of N derived from mineralization of soil organic matter. At the same time, δ13C values were declining, suggesting reduced photosynthesis and capacity for N assimilation. δ15N and δ13C values were more influenced by mean monthly temperature than by the accumulated monthly precipitation. In conclusion, ryegrass plants showed a clear seasonal pattern in N pools. Green leaves and stems of ryegrass plants generally seem to constitute a sink for NH3, while senescent leaves have a large potential for NH3 emission. However, management events such as fertilisation and grazing may create a high NH3 emission potential even in green plant parts. The obtained results provide input for future modelling of plant-atmosphere NH3 exchange.

  17. Nuclear astrophysics deep underground the case of the 15N(p,γ)16O reaction at LUNA

    CERN Document Server

    Mazzocchi, Chiara

    2010-01-01

    Measuring nuclear reactions of astrophysical interest at the relevant energies is not always possible on the Earth’s surface because of the cosmic-ray background that dominates the spectra. The LUNA collaboration exploits the lowbackground enviroment of Gran Sasso National Laboratory to study these reactions at or close to the Gamow peak. The latest experimental efforts included the measurement of the 15N(p,γ)16O at beam energies between 77 and 350 keV. The status of these measurements is summarised in this contribution.

  18. Influence of 15N enrichment on the net isotopic fractionation factor during the reduction of nitrate to nitrous oxide in soil

    DEFF Research Database (Denmark)

    Mathieu, O.; Levegue, J.; Henault, C.

    2007-01-01

    or relatively low (15)N enrichment levels and requires a good knowledge of the isotopic fractionation effect inherent to this biological mechanism. This paper reports the measurement of the net and instantaneous isotopic fractionation factor (alpha(i)(s/p)) during the denitrification of NO(3)(-) to N(2)O over...... a range of (15)N substrate enrichments (0.37 to 1.00 atom% (15)N). At natural abundance level, the isotopic fractionation effect reported falls well within the range of data previously observed. For (15)N-enriched substrate, the value of alpha(i)(s/p) was not constant and decreased from 1.024 to 1......Nitrous oxide, a greenhouse gas, is mainly emitted from soils during the denitrification process. Nitrogen stable-isotope investigations can help to characterise the N(2)O source and N(2)O production mechanisms. The stable-isotope approach is increasingly used with (15)N natural abundance...

  19. Shifts in Ross Sea food web structure as indicated by δ15N and δ13C values of fossil Antarctic seals

    Science.gov (United States)

    Leopold, A.; Brault, E.; McMahon, K.

    2013-12-01

    As climate change continues to mount, there is a growing need for understanding its effects on biological-physical interactions of marine ecosystems. Assessing the effects of anthropogenic activities on the coastal marine ecosystem involves understanding the underlying mechanisms driving these changes as well as establishing baselines of the natural system. Preliminary findings have indicated shifts in bulk carbon (C) and nitrogen (N) isotopic values of southern elephant seal (Mirounga leonina) samples, collected in the Dry Valleys of Antarctica in the Ross Sea region, over approximately the last 7,000 years. These shifts could result from 1) seals changing their foraging location and/or diet over this time, 2) climate change-induced shifts in the biogeochemistry at the base of the food web, or 3) some combination of both processes. We explored the patterns of long-term change in Ross Sea food web structure by examining the stable isotope values of three top predators in this system, Weddell seals (Leptonychotes weddellii), leopard seals (Hydrurga leptonyx), and crabeater seals (Lobodon carcinophagus). Fossil seal samples were collected in the Dry Valleys during the austral summer of 2012/13 and then analyzed for bulk C and N isotopes via an elemental analyzer/isotope-ratio mass spectrometer (EA/IRMS). Our initial findings indicate that C isotopic values of fossil seal samples from Weddell, leopard, and crabeater seals were more enriched than isotopic values of modern seals of the same species (e.g., δ13C = -22.79 × 0.92 ‰ and -26.71 × 0.50 ‰ for fossil and modern crabeater seals, respectively). Given the relatively consistent diet of crabeater seals, these findings suggest a shift in baseline food web structure occurred over the last 10,000 years, either through changes in foraging location or local shifts in biogeochemistry. For all species, N isotopic values are widely variable (e.g., 7.28 to 16.0 δ15N ‰ for the Weddell seal), which may be a result of

  20. Succesful labelling schemes

    DEFF Research Database (Denmark)

    Juhl, Hans Jørn; Stacey, Julia

    2001-01-01

    It is usual practice to evaluate the success of a labelling scheme by looking at the awareness percentage, but in many cases this is not sufficient. The awareness percentage gives no indication of which of the consumer segments that are aware of and use labelling schemes and which do not....... In the spring of 2001 MAPP carried out an extensive consumer study with special emphasis on the Nordic environmentally friendly label 'the swan'. The purpose was to find out how much consumers actually know and use various labelling schemes. 869 households were contacted and asked to fill in a questionnaire....... 664 households returned a completed questionnaire. There were five answering categories for each label in the questionnaire: * have not seen the label before. * I have seen the label before but I do not know the precise contents of the labelling scheme. * I have seen the label before, I do not know...

  1. PARTITIONING THE RELATIVE INFLUENCE OF SOIL N, MYCORRHIZAE, AND FOLIAR N UPTAKE ON FOLIAR δ15N PATTERNS: CAN WE DETECT FOLIAR UPTAKE OF REACTIVE N?

    Science.gov (United States)

    Vallano, D.; Sparks, J. P.

    2009-12-01

    Vegetation is an important sink for atmospheric reactive N in N-limited systems and may be capable of incorporating reactive N compounds directly into leaves through the foliar uptake pathway. A proxy for atmospheric reactive N entering vegetation would be useful to estimate the impact of direct foliar N uptake on plant metabolism. Natural abundance foliar N isotopic composition (δ15N) is a practical tool for this purpose because plant-available N sources often have different isotopic compositions. Current understanding of foliar δ15N suggests these values primarily represent the integration of soil δ15N, direct foliar N uptake, mycorrhizal fractionation, and within-plant fractionations. Using a potted plant mesocosm system, we estimated the influence of mycorrhizae on foliar δ15N patterns in red maple (Acer rubrum) seedlings along an N deposition gradient in New York State. We found that mycorrhizal associations altered foliar δ15N in red maple seedlings from 0.03 - 1.01‰ across sites. Along the same temporal and spatial scales, we examined the influence of soil δ15N, foliar N uptake, and mycorrhizae on foliar δ15N in adult stands of American beech (Fagus grandifolia), black birch (Betula lenta), red maple (A. rubrum), and red oak (Quercus rubra). Using multiple regression models, atmospheric NO2 concentration explained 0%, 69%, 23%, and 45% of the residual variation in foliar δ15N remaining in American beech, red maple, red oak, and black birch, respectively, after accounting for soil δ15N. Our results suggest that foliar δ15N may be used to estimate pollution-derived atmospheric reactive N entering vegetation via the foliar N uptake pathway.

  2. A simple method for the removal of dissolved organic matter and δ15N analysis of NO3(-) from freshwater.

    Science.gov (United States)

    Huber, Benjamin; Bernasconi, Stefano M; Pannatier, Elisabeth Graf; Luster, Jörg

    2012-06-30

    Stable isotopes of nitrogen in nitrate (NO(3)(-)) are frequently used to identify nitrate sources and to study nitrogen (N) transformation processes, but the measurement methods available are generally rather labor intensive and/or costly, and dissolved organic matter (DOM) can interfere with the δ(15)N signature of nitrate. We therefore have developed a simple cleanup procedure for freshwater samples with low nitrate and high DOM concentrations. Nitrate and DOM are extracted from a freeze-dried water sample by using a concentrated sodium hydroxide solution. By the subsequent addition of acetone, two liquid layers are formed, and nitrate migrates into the acetone while DOM remains in the concentrated NaOH solution, thus separating the nitrate from the DOM. For nitrogen isotope analysis, purified nitrate salts are combusted at 1030 °C to produce N(2) gas in an elemental analyzer (EA) coupled to an isotope ratio mass spectrometer (IRMS). With this novel technique up to 99% of DOM could be removed from river water and soil solutions. The method has been tested for sample amounts as small as 4 µmol NO(3)(-) with a precision of <0.1‰ (1SD). Nitrate standards are reproduced accurately without any blank correction. The benefits of this method are the lack of interferences derived from DOM on the δ(15)N signature and the ease of sample preparation. Copyright © 2012 John Wiley & Sons, Ltd.

  3. Traceability of animal meals in Japanese quail eggs using the technique of 13C e 15N* stable isotopes

    Directory of Open Access Journals (Sweden)

    C Mori

    2013-03-01

    Full Text Available The objective of this study was to trace the inclusion of bovine meat and bone meal (BMBM in the diet of Japanese quails by analyzing eggs and egg fractions (yolk and albumen by the technique of carbon-13 (13C and nitrogen-15 (15N stable isotopes. In the trial, 120 Japanese quails were distributed in six treatments with four replicates of five birds each. The following treatments were applied: feed based on corn and soybean meal, containing graded BMBM inclusions (0, 1, 2, 3, 4 or 5%. After 42 days, 20 eggs per treatment were randomly collected for three consecutive days. Ten eggs were used for yolk and albumen sample collection, and ten for total egg sample collection. It was possible to detect the dietary inclusion of 1% BMBM in the egg and its fractions. Therefore, the technique of isotopes 13C and 15N is able of tracing since 1% inclusion level of BMBM in the diet of Japanese quails in eggs and their fractions.

  4. The agricultural history of human-nitrogen interactions as recorded in ice core δ15N-NO3-

    Science.gov (United States)

    Felix, J. David; Elliott, Emily M.

    2013-04-01

    The advent and industrialization of the Haber Bosch process in the early twentieth century ushered in a new era of reactive nitrogen distributions on Earth. Since the appearance of the first commercial scale Haber Bosch fertilizer plants, fertilizer application rates have greatly increased in the U.S. While the contributions of fertilizer runoff to eutrophication and anoxic dead zones in coastal regions have been well-documented, the potential influences of increased fertilizer applications on air quality and precipitation chemistry are poorly constrained. Here we combine a 255-year record of precipitation nitrate isotopes preserved in a Greenland ice core, historical reconstructions of fertilizer application rates, and field characterization of the isotopic composition of nitrogen oxides produced biogenically in soils, to provide new constraints on the contributions of biogenic emissions to North American NOx inventories. Our results indicate that increases in twentieth century commercial fertilizer use led to large increases in soil NO, a byproduct released during nitrification and denitrification reactions. These large shifts in soil NO production are evidenced by sharp declines in ice core δ15N-NO3- values. Further, these results suggest that biogenic NOx emissions are underestimated by two to four fold in the U.S. NOx emission inventories used to construct global reactive nitrogen budgets. These results demonstrate that nitrate isotopes in ice cores, coupled with newly constrained δ15N-NOx values for NOx emission sources, provide a novel means for estimating contemporary and historic contributions from individual NOx emission sources to deposition.

  5. Changes in Rhodospirillum rubrum cytochrome c/sub 2/ and subsequent renaturation: An /sup 15/N NMR study

    Energy Technology Data Exchange (ETDEWEB)

    Yu, L.P.; Smith, G.M.

    1988-05-01

    The /sup 15/N-enriched ferrocytochrome c/sub 2/from Rhodospirillum rubrum was studied by /sup 15/N NMR at different solvent pH values. The mobility and chemical shift to the N-terminal glutamic acid (335.4 ppm at pH 5.1) were found to depend on pH. It was least mobile between pH 8 and 9.0, which is explained in terms of pH-dependent conformational changes and formation of salt linkages and/or hydrogen bonds. The resonances of the lysine side chains are centered around 341.7 ppm at low pH and move upfield with pH by about 8.4 ppm with pH/sub a/ values of 10.8. The exchange rates of the epsilonNH protons are lowest near the pK/sub a/ values. The protein is very stable in the pH range between 4.9 and 10.0 but unfolds abruptly at pH 10.5-11. Denaturation was verified by the measurement of several parameters by NMR. The renaturation of the protein demonstrates that the folding begins with reformation of home coordination and establishment of a hydrophobic core, followed by positioning of side chains and peptide backbones linking the nucleation centers. The repositioning processes had time scales of minutes to hours in contrast to the reported values of seconds in some studies.

  6. pH-induced changes in Rhodospirillum rubrum cytochrome c2 and subsequent renaturation: an 15N NMR study.

    Science.gov (United States)

    Yu, L P; Smith, G M

    1988-05-01

    The 15N-enriched ferrocytochrome c2 from Rhodospirillum rubrum was studied by 15N NMR at different solvent pH values. The mobility and chemical shift of the N-terminal glutamic acid (335.4 ppm at pH 5.1) were found to depend on pH. It was least mobile between pH 8 and 9.0, which is explained in terms of pH-dependent conformational changes and formation of salt linkages and/or hydrogen bonds. The resonances of the lysine side chains are centered around 341.7 ppm at low pH and move upfield with pH by about 8.4 ppm with pKa values of 10.8. The exchange rates of the epsilon NH protons are lowest near their pKa values. The protein is very stable in the pH range between 4.9 and 10.0 but unfolds abruptly at pH 10.5-11. Denaturation was verified by the measurement of several parameters by NMR. The renaturation of the protein demonstrates that the folding begins with reformation of heme coordination and establishment of a hydrophobic core, followed by positioning of side chains and peptide backbones linking the nucleation centers. The repositioning processes had time scales of minutes to hours in contrast to the reported values of seconds in some studies.

  7. Ecosystem extent and fragmentation

    Science.gov (United States)

    Sayre, Roger; Hansen, Matt

    2017-01-01

    One of the candidate essential biodiversity variable (EBV) groups described in the seminal paper by Pereira et al. (2014) concerns Ecosystem Structure. This EBV group is distinguished from another EBV group which encompasses aspects of Ecosystem Function. While the Ecosystem Function EBV treats ecosystem processes like nutrient cycling, primary production, trophic interactions, etc., the Ecosystem Structure EBV relates to the set of biophysical properties of ecosystems that create biophysical environmental context, confer biophysical structure, and occur geographically. The Ecosystem Extent and Fragmentation EBV is one of the EBVs in the Ecosystem Structure EBV group.Ecosystems are understood to exist at multiple scales, from very large areas (macro-ecosystems) like the Arctic tundra, for example, to something as small as a tree in an Amazonian rain forest. As such, ecosystems occupy space and therefore can be mapped across any geography of interest, whether that area of interest be a site, a nation, a region, a continent, or the planet. One of the most obvious and seemingly straightforward EBVs is Ecosystem Extent and Fragmentation. Ecosystem extent refers to the location and geographic distribution of ecosystems across landscapes or in the oceans, while ecosystem fragmentation refers to the spatial pattern and connectivity of ecosystem occurrences on the landscape.

  8. Uptake and incorporation of {sup 15}N marked nitrogen oxides by seasonal and woddy plants; Aufnahme und Einbau {sup 15}N-markierter Stickoxide durch krautige und holzige Pflanzen

    Energy Technology Data Exchange (ETDEWEB)

    Eickriede, A.

    1998-07-01

    It the Research Centre Juelich a special system was developed to expose plants under defined climatic conditions to a nitrogen oxide enriched atmosphere. In completition and extension to former studies sunflowers (Helianthus annuus L.), mays (Zea mays L.) and poplar (Populus tremula x P. alba) were exposed to nitrogen oxides. By using {sup 15}N enriched nitrogen oxides ({sup 15}NO{sub 2}, and {sup 15}NO, summarised as {sup 15}NO{sub x}) the uptake and incorporation of {sup 15}NOx in dependance of the exposition concentration (30 to 100 ppb {sup 15}NO, 20 ppb {sup 15}NO{sub 2}), nitrogen nutrition (nitrate or ammonium), and harvesting time were examined. Moreover, the influence of nitrogen oxide exposition on the distribution pattern of {sup 15}NO{sub x} nitrogen within the plants and on the amino acid content of plant leaves was investigated. (orig.)

  9. Food Label and You

    Medline Plus

    Full Text Available ... Finding Nutrition Information on the Road) Game Show Review (Are You Smarter Than A Food Label?) The ... TV for CFSAN. back to menu Game Show Review (Are You Smarter Than A Food Label?) Spoof ...

  10. Pesticide Product Label System

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Pesticide Product Label System (PPLS) provides a collection of pesticide product labels (Adobe PDF format) that have been approved by EPA under Section 3 of the...

  11. Food Label and You

    Medline Plus

    Full Text Available ... Nutrition Facts label for packaged foods. For more information, see Changes to the Nutrition Facts Label . FDA ... Gametime/Play By Play) Road Food (Finding Nutrition Information on the Road) Game Show Review (Are You ...

  12. Food Label and You

    Medline Plus

    Full Text Available ... Road Food (Finding Nutrition Information on the Road) Game Show Review (Are You Smarter Than A Food Label?) The Food Label & You (full video) Introduction back to menu CSI (Calorie Scene Investigators) ...

  13. Mental Labels and Tattoos

    Science.gov (United States)

    Hyatt, I. Ralph

    1977-01-01

    Discusses the ease with which mental labels become imprinted in our system, six basic axioms for maintaining negative mental tattoos, and psychological processes for eliminating mental tattoos and labels. (RK)

  14. Semiotic labelled deductive systems

    Energy Technology Data Exchange (ETDEWEB)

    Nossum, R.T. [Imperial College of Science, Technology and Medicine, London (United Kingdom)

    1996-12-31

    We review the class of Semiotic Models put forward by Pospelov, as well as the Labelled Deductive Systems developed by Gabbay, and construct an embedding of Semiotic Models into Labelled Deductive Systems.

  15. Food Label and You

    Medline Plus

    Full Text Available ... has issued final changes to update the Nutrition Facts label for packaged foods. For more information, see Changes to the Nutrition Facts Label . FDA presents an entertaining and educational tool ...

  16. Food Label and You

    Medline Plus

    Full Text Available ... select on any of the individual segments below. Introduction CSI (Calorie Scene Investigators) Servings The 5-20 ... Food Label?) The Food Label & You (full video) Introduction back to menu CSI (Calorie Scene Investigators) A ...

  17. Pesticide Labeling Questions & Answers

    Science.gov (United States)

    Pesticide manufacturers, applicators, state regulatory agencies, and other stakeholders raise questions or issues about pesticide labels. The questions on this page are those that apply to multiple products or address inconsistencies among product labels.

  18. Nutritional status of sugar cane (planted cane) in {sup 15}N experiments;Estado nutricional da cultura de cana-de-acucar (cana-planta) em experimentos com {sup 15}N{sup (1)}

    Energy Technology Data Exchange (ETDEWEB)

    Faroni, Carlos Eduardo, E-mail: cfaroni@ctc.com.b [Centro de Tecnologia Canavieira (CTC), Piracicaba, SP (Brazil); Trivelin, Paulo Cesar Ocheuze; Franco, Henrique Coutinho Junqueira, E-mail: pcotrive@cena.usp.b, E-mail: hjfranco@cena.usp.b [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil); Vitti, Andre Cesar, E-mail: acvitti@apta.sp.gov.b [Agencia Paulista de Tecnologia dos Agronegocios (APTA), Piracicaba, SP (Brazil). Polo Centro Sul; Otto, Rafael, E-mail: rotto@esalq.usp.b [Universidade de Sao Paulo (USP), Piracicaba, SP (Brazil). Escola Superior de Agricultura Luiz de Queiroz; Cantarella, Heitor, E-mail: cantarella@iac.sp.gov.b [Instituto Agronomico de Campinas (IAC), SP (Brazil)

    2009-11-15

    Studies with stable isotopes are becoming more common due to the increased safety of operation and quality and reliability of results. However, the use of microplots is required to decrease the costs of such studies. Since microplots are small compared to regular plot areas, the purpose of this study was to investigate whether nutritional data based on microplot samples can adequately represent the whole area, in a comparison of the nutritional status of microplot sugar cane plants at their maximum development stage with those of the regular plots in experiments with N rates. Three experiments were set up, with three N rates (40, 80, and 120 kg ha{sup -1} N) and a control, with four repetitions, in a randomized complete block design, in the state of Sao Paulo. Microplots of 3 m{sup 2} containing {sup 15}N-fertilizer (5.04% atom {sup 15}N) were included in the main plots formed by 48 lines of sugar cane spaced 1.5 m apart. At the time of maximum development stage, diagnostic leaves were collected in the main and microplots to evaluate the nutritional status of plants by analyzing the total concentration of macro nutrients. There were no differences in N, P, Ca, Mg, and S concentrations in the diagnostic leaves from the main and microplots, so that the latter can be considered representative of the experimental area. Higher nitrogen fertilizer rates induced increased concentrations of not only N, but also of P, Ca, Mg, and S in the diagnostic leaves. (author)

  19. Nutrient regime shift in the western North Atlantic indicated by compound-specific δ15N of deep-sea gorgonian corals.

    Science.gov (United States)

    Sherwood, Owen A; Lehmann, Moritz F; Schubert, Carsten J; Scott, David B; McCarthy, Matthew D

    2011-01-18

    Despite the importance of the nitrogen (N) cycle on marine productivity, little is known about variability in N sources and cycling in the ocean in relation to natural and anthropogenic climate change. Beyond the last few decades of scientific observation, knowledge depends largely on proxy records derived from nitrogen stable isotopes (δ(15)N) preserved in sediments and other bioarchives. Traditional bulk δ(15)N measurements, however, represent the combined influence of N source and subsequent trophic transfers, often confounding environmental interpretation. Recently, compound-specific analysis of individual amino acids (δ(15)N-AA) has been shown as a means to deconvolve trophic level versus N source effects on the δ(15)N variability of bulk organic matter. Here, we demonstrate the first use of δ(15)N-AA in a paleoceanographic study, through analysis of annually secreted growth rings preserved in the organic endoskeletons of deep-sea gorgonian corals. In the Northwest Atlantic off Nova Scotia, coral δ(15)N is correlated with increasing presence of subtropical versus subpolar slope waters over the twentieth century. By using the new δ(15)N-AA approach to control for variable trophic processing, we are able to interpret coral bulk δ(15)N values as a proxy for nitrate source and, hence, slope water source partitioning. We conclude that the persistence of the warm, nutrient-rich regime since the early 1970s is largely unique in the context of the last approximately 1,800 yr. This evidence suggests that nutrient variability in this region is coordinated with recent changes in global climate and underscores the broad potential of δ(15)N-AA for paleoceanographic studies of the marine N cycle.

  20. δ15N measurement of organic and inorganic substances by EA-IRMS: a speciation-dependent procedure.

    Science.gov (United States)

    Gentile, Natacha; Rossi, Michel J; Delémont, Olivier; Siegwolf, Rolf T W

    2013-01-01

    Little attention has been paid so far to the influence of the chemical nature of the substance when measuring δ(15)N by elemental analysis (EA)-isotope ratio mass spectrometry (IRMS). Although the bulk nitrogen isotope analysis of organic material is not to be questioned, literature from different disciplines using IRMS provides hints that the quantitative conversion of nitrate into nitrogen presents difficulties. We observed abnormal series of δ(15)N values of laboratory standards and nitrates. These unexpected results were shown to be related to the tailing of the nitrogen peak of nitrate-containing compounds. A series of experiments were set up to investigate the cause of this phenomenon, using ammonium nitrate (NH(4)NO(3)) and potassium nitrate (KNO(3)) samples, two organic laboratory standards as well as the international secondary reference materials IAEA-N1, IAEA-N2-two ammonium sulphates [(NH(4))(2)SO(4)]-and IAEA-NO-3, a potassium nitrate. In experiment 1, we used graphite and vanadium pentoxide (V(2)O(5)) as additives to observe if they could enhance the decomposition (combustion) of nitrates. In experiment 2, we tested another elemental analyser configuration including an additional section of reduced copper in order to see whether or not the tailing could originate from an incomplete reduction process. Finally, we modified several parameters of the method and observed their influence on the peak shape, δ(15)N value and nitrogen content in weight percent of nitrogen of the target substances. We found the best results using mere thermal decomposition in helium, under exclusion of any oxygen. We show that the analytical procedure used for organic samples should not be used for nitrates because of their different chemical nature. We present the best performance given one set of sample introduction parameters for the analysis of nitrates, as well as for the ammonium sulphate IAEA-N1 and IAEA-N2 reference materials. We discuss these results considering the

  1. A Label to Regulate

    DEFF Research Database (Denmark)

    Tricoire, Aurélie; Boxenbaum, Eva; Laurent, Brice

    This paper examines the role labelling plays in the government of the contemporary economy.1Drawing on a detailed study of BBC-Effinergy, a French label for sustainable construction, we showhow the adoption and evolution of voluntary labels can be seen as emblematic of a governmentthrough experim...

  2. Labeling strategies for bioassays

    NARCIS (Netherlands)

    Hempen, C.M.; Karst, U.

    2006-01-01

    Different labeling strategies for enzymatic assays and immunoassays are reviewed. Techniques which make use of direct detection of a label, e.g. radioimmunoassays, are discussed, as are techniques in which the label is associated with inherent signal amplification. Examples of the latter, e.g.

  3. Variabilidade isotópica (δ13 C e δ15N em produtores primários de ambientes terrestres e de água doce Isotopes variability δ13C and δ15N in primary producers from terrestrial and freshwater environments

    Directory of Open Access Journals (Sweden)

    Célia de Almeida Lopes

    2002-05-01

    Full Text Available Em Ciências Ambientais o uso de δ13C e δ15N como traçadores biológicos é dependente do entendimento dos processos físicos, químicos e biológicos que determinam a proporção entre isótopos leves e pesados de uma amostra em estudo. A presente síntese procura discutir os fracionamentos isotópicos associados com as diferentes vias fotossintéticas, e relacionar as características intrínsecas dos ecossistemas terrestres e aquáticos que influenciam na amplitude das variações isotópicas dos produtores primários na natureza. A dinâmica dos efeitos isotópicos nos ambientes aquáticos é altamente complexa, resultando em uma variabilidade isotópica mais ampla do que aquela observada nos ambientes terrestres. Nesses ambientes, a integração de técnicas isotópicas permite melhor dimensionar as fontes autotróficas de energia que sustentam a base de teias alimentares e estabelecer as conexões entre os organismos produtores e consumidoresIn environmental science the use of δ13C and δ15N as biological tracers is dependent on the understanding of the physical, chemical and biological processes that determine the proportion among slight and heavier isotopes in a study sample. The present synthesis searches to elucidate isotopic fractionations associated with different photosynthetic pathways and relate intrinsic characteristics of the aquatic and terrestrial ecosystems that influence the amplitude of isotopes variation on primary producers in nature. The dynamic of the effects of isotopes in aquatic environments is highly complex, resulting in a more sample variation than those observed in terrestrial environments. In aquatic environments, the integration the isotopic techniques permit better measures of autotrophic energy sources that support the base of food webs and better establish connection among producers and consumers

  4. An AlN/Al{sub 0.85}Ga{sub 0.15}N high electron mobility transistor

    Energy Technology Data Exchange (ETDEWEB)

    Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.; Douglas, Erica A.; Sanchez, Carlos A.; King, Michael P.; Coltrin, Michael E.; Fortune, Torben R.; Kaplar, Robert J. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1085 (United States)

    2016-07-18

    An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al{sub 0.85}Ga{sub 0.15}N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high I{sub on}/I{sub off} current ratio greater than 10{sup 7} and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. The room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.

  5. Diabetes induced renal urea transport alterations assessed with 3D hyperpolarized 13 C,15 N-Urea.

    Science.gov (United States)

    Bertelsen, Lotte B; Nielsen, Per M; Qi, Haiyun; Nørlinger, Thomas S; Zhang, Xiaolu; Stødkilde-Jørgensen, Hans; Laustsen, Christoffer

    2017-04-01

    In the current study, we investigated hyperpolarized urea as a possible imaging biomarker of the renal function by means of the intrarenal osmolality gradient. Hyperpolarized three-dimensional balanced steady state 13 C MRI experiments alongside kidney function parameters and quantitative polymerase chain reaction measurements was performed on two groups of rats, a streptozotocin type 1 diabetic group and a healthy control group. A significant decline in intrarenal steepness of the urea gradient was found after 4 weeks of untreated insulinopenic diabetes in agreement with an increased urea transport transcription. MRI and hyperpolarized [13 C,15 N]urea can monitor the changes in the corticomedullary urea concentration gradients in diabetic and healthy control rats. Magn Reson Med 77:1650-1655, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  6. Multiple regression models of δ13C and δ15N for fish populations in the eastern Gulf of Mexico

    Science.gov (United States)

    Radabaugh, Kara R.; Peebles, Ernst B.

    2014-08-01

    Multiple regression models were created to explain spatial and temporal variation in the δ13C and δ15N values of fish populations on the West Florida Shelf (eastern Gulf of Mexico, USA). Extensive trawl surveys from three time periods were used to acquire muscle samples from seven groundfish species. Isotopic variation (δ13Cvar and δ15Nvar) was calculated as the deviation from the isotopic mean of each fish species. Static spatial data and dynamic water quality parameters were used to create models predicting δ13Cvar and δ15Nvar in three fish species that were caught in the summers of 2009 and 2010. Additional data sets were then used to determine the accuracy of the models for predicting isotopic variation (1) in a different time period (fall 2010) and (2) among four entirely different fish species that were collected during summer 2009. The δ15Nvar model was relatively stable and could be applied to different time periods and species with similar accuracy (mean absolute errors 0.31-0.33‰). The δ13Cvar model had a lower predictive capability and mean absolute errors ranged from 0.42 to 0.48‰. δ15N trends are likely linked to gradients in nitrogen fixation and Mississippi River influence on the West Florida Shelf, while δ13C trends may be linked to changes in algal species, photosynthetic fractionation, and abundance of benthic vs. planktonic basal resources. These models of isotopic variability may be useful for future stable isotope investigations of trophic level, basal resource use, and animal migration on the West Florida Shelf.

  7. Citric acid traps to replace sulphuric acid in the ammonia diffusion of dilute water samples for 15N analysis.

    Science.gov (United States)

    Schleppi, Patrick; Bucher-Wallin, Inga; Saurer, Matthias; Jäggi, Maya; Landolt, Werner

    2006-01-01

    The analysis of 15N in aqueous samples requires the concentration of dissolved nitrogen (N) into a small volume that can be analysed by mass spectrometry. This is conveniently achieved by the NH3 diffusion technique, where NH4+ is captured on small acidified filters enclosed in PTFE. NO3- can be analysed the same way by reducing it to NH4+ with Devarda's alloy. H2SO4 is commonly used for the acidification of the filters. During combustion, however, this acid leads to the production of SO2 and elemental sulphur, which both have detrimental effects on the mass spectrometer. We propose here to replace H2SO4 with citric acid because it is combusted completely to CO2 and H2O in the elemental analyser before entering the mass spectrometer. Citric acid was found to give comparable results in terms of N recovery and 15N values, both for NH4+ and for NO3- samples. Blank samples revealed that N contamination was slightly lower using citric instead of sulphuric acid as acidifier of the glass filters. NH4+ samples first concentrated over cation-exchange columns were strongly acidic and several methods were tested to raise the pH for the subsequent diffusion. These samples gave incomplete N recoveries, but this problem was independent of the acid used on the filters and of the final pH of the sample. Complete recovery was achieved only by increasing the volume of the eluate from the columns. Citric acid can thus generally be recommended instead of H2SO4 for ammonia diffusion. Copyright 2006 John Wiley & Sons, Ltd.

  8. Transformation of Digital Ecosystems

    DEFF Research Database (Denmark)

    Henningsson, Stefan; Hedman, Jonas

    2014-01-01

    the Digital Ecosystem Technology Transformation (DETT) framework for explaining technology-based transformation of digital ecosystems by integrating theories of business and technology ecosystems. The framework depicts ecosystem transformation as distributed and emergent from micro-, meso-, and macro- level...... coopetition. The DETT framework consists an alternative to the existing explanations of digital ecosystem transformation as the rational management of one central actor balancing ecosystem tensions. We illustrate the use of the framework by a case study of transformation in the digital payment ecosystem......In digital ecosystems, the fusion relation between business and technology means that the decision of technical compatibility of the offering is also the decision of how to position the firm relative to the coopetive relations that characterize business ecosystems. In this article we develop...

  9. Application of Nitrogen and Carbon Stable Isotopes ([delta]15N and [delta]13C) to Quantify Food Chain Length and Trophic Structure

    National Research Council Canada - National Science Library

    Matthew J Perkins; McDonald, Robbie; Veen, J; Kelly, Simon; Rees, Gareth; Bearhop, Stuart

    2014-01-01

      Increasingly, stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures...

  10. On Online Labeling with Polynomially Many Labels

    DEFF Research Database (Denmark)

    Babka, Martin; Bulánek, Jan; Cunat, Vladimír

    2012-01-01

    In the online labeling problem with parameters n and m we are presented with a sequence of nkeys from a totally ordered universe U and must assign each arriving key a label from the label set {1,2,…,m} so that the order of labels (strictly) respects the ordering on U. As new keys arrive it may...... are known that use O(n logn) relabelings. A matching lower bound was claimed in [7]. That proof involved two distinct steps: a lower bound for a problem they call prefix bucketing and a reduction from prefix bucketing to online labeling. The reduction seems to be incorrect, leaving a (seemingly significant......) gap in the proof. In this paper we close the gap by presenting a correct reduction to prefix bucketing. Furthermore we give a simplified and improved analysis of the prefix bucketing lower bound. This improvement allows us to extend the lower bounds for online labeling to the case where the number m...

  11. Macroalgae blooms and delta 15N in subtropical coastal lagoons from the Southeastern Gulf of California: discrimination among agricultural, shrimp farm and sewage effluents.

    Science.gov (United States)

    Piñón-Gimate, Alejandra; Soto-Jiménez, Martín F; Ochoa-Izaguirre, María Julia; García-Pagés, Eynar; Páez-Osuna, Federico

    2009-08-01

    Macroalgae blooms of Gracilaria vermiculophylla, Hypnea spinella and Spyridia filamentosa have been found in coastal lagoons in the SE Gulf of California. Agriculture, livestock, shrimp and poultry farms and sewage contribute anthropogenic nitrogen to the systems. The delta(15)N of these sources, water column and macroalgae were studied in order to identify the N supply for macroalgae blooms. delta(15)N of three species of macroalgae (4.3-13.6 per thousand) were enriched compared to the water column (delta(15)N-NO(3)(-) 3.7-6.8 per thousand), probably because of fractioning from the macroalgae. delta(15)N of POM (1.4-10.3 per thousand) was similar to the water column but the relationship was unclear. Depending on the site, macroalgae showed different delta(15)N values since some sites receive more or less influence from one given source of the associated watershed, which is reflected in the different delta(15)N values of the macroalgae of the same system and in the relative contributions of the sources.

  12. MINERALIZAÇÃO E VOLATILIZAÇÃO DO NITROGÊNIO DA VINHAÇA-15N NA PRESENÇA OU NÃO DE URÉIA E DE PALHA DE CANA- DE-AÇÚCAR MINERALIZATION AND VOLATILIZATION OF NITROGEN FROM VINASSE-15N IN THE PRESENCE OR ABSENCE OF UREA AND SUGARCANE TRASH

    Directory of Open Access Journals (Sweden)

    Vilma Maria Silva

    1999-01-01

    Full Text Available O N mineral e o N volatilizado derivado da vinhaça marcada com 15N foram determinados em amostras de dois solos (Podzólico Vermelho-Amarelo, arenoso - PV, e Latossolo Roxo, argiloso - LR do município de Piracicaba, SP, em experimento de laboratório. Os solos foram tratados com vinhaça marcada com 15N (V* na dose de 100 mg.kg-1 de N-vinhaça. Os tratamentos constaram da aplicação de vinhaça isoladamente (V*, de vinhaça e uréia (V*+U, de vinhaça e palha de cana-de-açúcar (V*+P, e de vinhaça mais uréia e palha (V*+U+P, e foram incubados por 7, 14, 21, 28 e 35 dias. As parcelas foram constituídas por 50 g de solo. As doses de incorporação de N-uréia e palha de cana-de-açúcar foram de 220 mg.kg-1 e 22 g.kg-1, respectivamente. As concentrações de N-NH4+ e N-NO3- no solo proveniente da vinhaça foram influenciadas pelo tipo de solo. A adição aos solos da uréia e da vinhaça promoveu uma maior disponibilidade de N-NH4+ e de N-NO3- proveniente da vinhaça. A adição de palha e de vinhaça não alterou as concentrações de N-NH4+ e de N-NO3- provenientes da vinhaça nos solos. A adição da palha, da uréia e da vinhaça não alterou as concentrações de N-NH4+ e as concentrações de N-NO3- aumentaram apenas no solo LR ao longo do tempo. As perdas por volatilização de N da vinhaça foram, em geral, crescentes, para todos os tratamentos no solo PV e mais elevadas (14 % que no solo LR (5%; neste, foram bem similares.The mineralized and volatilized nitrogen derived from vinasse labelled with 15N were determined in a laboratory experiment, using samples of two soils [a sandy Red-Yellow Podzolic - PV and a clayey Latosol - LR (Oxisol], collected in Piracicaba, SP, Brazil. The experiment consisted of four treatments: application of vinasse (V*; vinasse with urea (V*+U; vinasse with sugarcane straw (V*+P; and vinasse with urea and sugarcane straw (V*+U+P. Vinasse, labelled with 15N (V* was applied at a rate of 100 mg.kg-1 of N

  13. Nitrogen ({sup 15} N) fertilizer use in subsistence culture in the semi-arid soil of Northeast-Brazil; Utilizacao de fertilizante nitrogenado ({sup 15} N) em cultura de subsistencia no semi-arido nordestino

    Energy Technology Data Exchange (ETDEWEB)

    Sampaio, Everardo V.S.B.; Antonino, Antonio C.D.; Salcedo, Ignacio H. [Pernambuco Univ., Recife, PE (Brazil). Dept. de Energia Nuclear; Tiessen, Holm [Saskatchewan Univ., Saskatoon, SK (Canada). Inst. of Pedology

    1997-12-01

    Productivity in the semi-arid area of Northeast Brazil is limited by nitrogen deficiency but fertilizers are not used due to the risk of this investment, usually calculated considering the year of application. Part of the fertilizer accumulates in the soil and can be used in subsequent crops. To provide information on accumulation, an experiment was established at Coxixola, city Pernambuco state consisting of combinations of single and intercropped corn and beans, with and without nitrogen fertilization (16 Kg.ha-1). Planting was done in holes, 1,1 x 1,0 m apart and 15N ammonium nitrate was applied in the there central holes of the plots. At harvest, plants in these hole were analysed separately and the soil was sampled at threre depths and five distances from the point of application of the fertilizer. Productivities were low, without differences between fertilized and non fertilized treatments for grain but with differences for straw. Single corn absorbed more (34%) and retained more of the N fertilizer in the soil (50%) than single beans (16 e 28%) and intercrop (corn 15% beans 11% soil 48%). Part of the unrecovered fertilizer may have migrated out of the sampled volume. This migration and the losses in beans indicate that only a small effect is expected for the accumulated N in the soil. (author). 31 refs., 1 fig., 4 tabs.

  14. Closed-loop 15N measurement of N2O and its isotopomers for real-time greenhouse gas tracing

    Science.gov (United States)

    Slaets, Johanna; Mayr, Leopold; Heiling, Maria; Zaman, Mohammad; Resch, Christian; Weltin, Georg; Gruber, Roman; Dercon, Gerd

    2016-04-01

    Quantifying sources of nitrous oxide is essential to improve understanding of the global N cycle and to develop climate-smart agriculture, as N2O has a global warming potential 300 times higher than CO2. The isotopic signature and the intramolecular distribution (site preference) of 15N are powerful tools to trace N2O, but the application of these methods is limited as conventional methods cannot provide continuous and in situ data. Here we present a method for closed-loop, real time monitoring of the N2O flux, the isotopic signature and the intramolecular distribution of 15N by using off-axis integrated cavity output spectroscopy (ICOS, Los Gatos Research). The developed method was applied to a fertilizer inhibitor experiment, in which N2O emissions were measured on undisturbed soil cores for three weeks. The treatments consisted of enriched urea-N (100 kg urea-N/ha), the same fertilizer combined with the nitrification inhibitor nitrapyrin (375 g/100 kg urea), and control cores. Monitoring the isotopic signature makes it possible to distinguish emissions from soil and fertilizer. Characterization of site preference could additionally provide a tool to identify different microbial processes leading to N2O emissions. Furthermore, the closed-loop approach enables direct measurement on site and does not require removal of CO2 and H2O. Results showed that 75% of total N2O emissions (total=11 346 μg N2O-N/m2) in the fertilized cores originated from fertilizer, while only 55% of total emissions (total=2 450 μg N2ON/m2) stemmed from fertilizer for the cores treated with nitrapyrin. In the controls, N2O derived from soil was only 40% of the size of the corresponding pool from the fertilized cores, pointing towards a priming effect on the microbial community from the fertilizer and demonstrating the bias that could be introduced by relying on non-treated cores to estimate soil emission rates, rather than using the isotopic signature. The site preference increased linearly

  15. NMR assignments of sparsely labeled proteins using a genetic algorithm.

    Science.gov (United States)

    Gao, Qi; Chalmers, Gordon R; Moremen, Kelley W; Prestegard, James H

    2017-04-01

    Sparse isotopic labeling of proteins for NMR studies using single types of amino acid ((15)N or (13)C enriched) has several advantages. Resolution is enhanced by reducing numbers of resonances for large proteins, and isotopic labeling becomes economically feasible for glycoproteins that must be expressed in mammalian cells. However, without access to the traditional triple resonance strategies that require uniform isotopic labeling, NMR assignment of crosspeaks in heteronuclear single quantum coherence (HSQC) spectra is challenging. We present an alternative strategy which combines readily accessible NMR data with known protein domain structures. Based on the structures, chemical shifts are predicted, NOE cross-peak lists are generated, and residual dipolar couplings (RDCs) are calculated for each labeled site. Simulated data are then compared to measured values for a trial set of assignments and scored. A genetic algorithm uses the scores to search for an optimal pairing of HSQC crosspeaks with labeled sites. While none of the individual data types can give a definitive assignment for a particular site, their combination can in most cases. Four test proteins previously assigned using triple resonance methods and a sparsely labeled glycosylated protein, Robo1, previously assigned by manual analysis, are used to validate the method and develop a criterion for identifying sites assigned with high confidence.

  16. Measuring Entrepreneurial Ecosystems

    NARCIS (Netherlands)

    Stam, F.C.

    How can entrepreneurial ecosystems and productive entrepreneurship can be traced empirically and how is entrepreneurship related to entrepreneurial ecosystems. The analyses in this chapter show the value of taking a systems view on the context of entrepreneurship. We measure entrepreneurial

  17. Coral reefs - Specialized ecosystems

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, M.V.M.

    This paper discusses briefly some aspects that characterize and differentiate coral reef ecosystems from other tropical marine ecosystems. A brief account on the resources that are extractable from coral reefs, their susceptibility to natural...

  18. Mapping cultural ecosystem services:

    DEFF Research Database (Denmark)

    Paracchini, Maria Luisa; Zulian, Grazia; Kopperoinen, Leena

    2014-01-01

    Research on ecosystem services mapping and valuing has increased significantly in recent years. However, compared to provisioning and regulating services, cultural ecosystem services have not yet been fully integrated into operational frameworks. One reason for this is that transdisciplinarity...

  19. FWS Ecosystem Regions

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Digital ecosystem information portraying the location and boundaries of the ecosystems. The Service originally chose the U.S. Geological Survey's Hydrologic Unit Map...

  20. Tracking Nitrogen Source Using δ15N Reveals Human and Agricultural Drivers of Seagrass Degradation across the British Isles

    OpenAIRE

    Benjamin L. Jones; Benjamin L. Jones; Leanne C. Cullen-Unsworth; Leanne C. Cullen-Unsworth; Richard K. F. Unsworth; Richard K. F. Unsworth

    2018-01-01

    Excess nutrients shift the ecological balance of coastal ecosystems, and this eutrophication is an increasing problem across the globe. Nutrient levels may be routinely measured, but monitoring rarely attempts to determine the source of these nutrients, even though bio-indicators are available. Nitrogen stable isotope analysis in biota is one such bio-indicator, but across the British Isles, this is rarely used. In this study, we provide the first quantitative evidence of the anthropogenic dr...

  1. Complementary constraints from carbon (13C) and nitrogen (15N) isotopes on the glacial ocean's soft-tissue biological pump

    Science.gov (United States)

    Schmittner, A.; Somes, C. J.

    2016-06-01

    A three-dimensional, process-based model of the ocean's carbon and nitrogen cycles, including 13C and 15N isotopes, is used to explore effects of idealized changes in the soft-tissue biological pump. Results are presented from one preindustrial control run (piCtrl) and six simulations of the Last Glacial Maximum (LGM) with increasing values of the spatially constant maximum phytoplankton growth rate μmax, which accelerates biological nutrient utilization mimicking iron fertilization. The default LGM simulation, without increasing μmax and with a shallower and weaker Atlantic Meridional Overturning Circulation and increased sea ice cover, leads to 280 Pg more respired organic carbon (Corg) storage in the deep ocean with respect to piCtrl. Dissolved oxygen concentrations in the colder glacial thermocline increase, which reduces water column denitrification and, with delay, nitrogen fixation, thus increasing the ocean's fixed nitrogen inventory and decreasing δ15NNO3 almost everywhere. This simulation already fits sediment reconstructions of carbon and nitrogen isotopes relatively well, but it overestimates deep ocean δ13CDIC and underestimates δ15NNO3 at high latitudes. Increasing μmax enhances Corg and lowers deep ocean δ13CDIC, improving the agreement with sediment data. In the model's Antarctic and North Pacific Oceans modest increases in μmax result in higher δ15NNO3 due to enhanced local nutrient utilization, improving the agreement with reconstructions there. Models with moderately increased μmax fit both isotope data best, whereas large increases in nutrient utilization are inconsistent with nitrogen isotopes although they still fit the carbon isotopes reasonably well. The best fitting models reproduce major features of the glacial δ13CDIC, δ15N, and oxygen reconstructions while simulating increased Corg by 510-670 Pg compared with the preindustrial ocean. These results are consistent with the idea that the soft-tissue pump was more efficient

  2. Global Ecosystem Restoration Index

    DEFF Research Database (Denmark)

    Fernandez, Miguel; Garcia, Monica; Fernandez, Nestor

    2015-01-01

    The Global ecosystem restoration index (GERI) is a composite index that integrates structural and functional aspects of the ecosystem restoration process. These elements are evaluated through a window that looks into a baseline for degraded ecosystems with the objective to assess restoration...

  3. Ecosystem classification, Chapter 2

    Science.gov (United States)

    M.J. Robin-Abbott; L.H. Pardo

    2011-01-01

    The ecosystem classification in this report is based on the ecoregions developed through the Commission for Environmental Cooperation (CEC) for North America (CEC 1997). Only ecosystems that occur in the United States are included. CEC ecoregions are described, with slight modifications, below (CEC 1997) and shown in Figures 2.1 and 2.2. We chose this ecosystem...

  4. Towards ecosystem accounting

    NARCIS (Netherlands)

    Duku, C.; Rathjens, H.; Zwart, S.J.; Hein, L.

    2015-01-01

    Ecosystem accounting is an emerging field that aims to provide a consistent approach to analysing environment-economy interactions. One of the specific features of ecosystem accounting is the distinction between the capacity and the flow of ecosystem services. Ecohydrological modelling to support

  5. Rights to ecosystem services

    NARCIS (Netherlands)

    Davidson, M.

    2014-01-01

    Ecosystem services are the benefits people obtain from ecosystems. Many of these services are provided outside the borders of the land where they are produced; this article investigates who is entitled to these non-excludable ecosystem services from two libertarian perspectives. Taking a

  6. North Atlantic ecosystem shifts revealed by cod otolith δ15N and δ13C chronologies

    DEFF Research Database (Denmark)

    Pedersen, Jens Brøgger; Nielsen, Jens Munk; Steingrund, Petur

    annual mean values over time were seen in both ecosystems, suggesting δ15N & δ13C values were affected by the same overall processes. There were significant effects of climate variables (temperature, Atlantic Multi-decadal Oscillation (AMO) and Sub Polar Gyre index) on δ15N and δ13C chronologies in both...... catches. This indicates a large ecosystem shift in the Nuuk Fjord around 1970 and a smaller in 1995 and is further supported by the δ15N & δ13C bi-plot that shows a clear separation in signatures before and after 1970. To separate baseline shifts from trophic shifts new δ15N and δ13C chronologies...

  7. Similarities and differences in 13C and 15N stable isotope ratios in two non-lethal tissue types from shovelnose sturgeon Scaphirhynchus platorynchus (Rafinesque, 1820)

    Science.gov (United States)

    DeVries, R. J.; Schramm, Harold L.

    2015-01-01

    We tested the hypothesis that δ13C and δ15N signatures of pectoral spines would provide measures of δ13C and δ15N similar to those obtained from fin clips for adult shovelnose sturgeon Scaphirhynchus platorynchus. Thirty-two shovelnose sturgeon (fork length [FL] = 500–724 mm) were sampled from the lower Mississippi River, USA on 23 February 2013. Isotopic relationships between the two tissue types were analyzed using mixed model analysis of covariance. Tissue types differed significantly for both δ13C (P spine: mean = −23.83, SD = 0.62; fin clip: mean = −25.74, SD = 0.97) and δ15N (P = 0.01; spine: mean = 17.01, SD = 0.51; fin clip: mean = 17.19, SD = 0.62). Neither FL nor the FL × tissue type interaction had significant (P > 0.05) effects on δ13C. Fin clip δ13C values were highly variable and weakly correlated (r = 0.16, P = 0.40) with those from pectoral spines. We found a significant FL-tissue type interaction for δ15N, reflecting increasing δ15N with FL for spines and decreasing δ15N with FL for fin clips. These results indicate that spines are not a substitute for fin clip tissue for measuring δ13C and δ15N for shovelnose sturgeon in the lower Mississippi River, but the two tissues have different turnover rates they may provide complementary information for assessing trophic position at different time scales.

  8. FIRST MEASUREMENTS OF {sup 15}N FRACTIONATION IN N{sub 2}H{sup +} TOWARD HIGH-MASS STAR-FORMING CORES

    Energy Technology Data Exchange (ETDEWEB)

    Fontani, F. [INAF-Osservatorio Astrofisico di Arcetri, L.go E. Fermi 5, I-50125 Firenze (Italy); Caselli, P.; Bizzocchi, L. [Max Planck Institute for Extraterrestrial Physics, Giessenbachstrasse 1, D-85748 Garching (Germany); Palau, A. [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090 Morelia, Michoacán, México (Mexico); Ceccarelli, C. [Univ. Grenoble Alpes, IPAG, F-38000 Grenoble (France)

    2015-08-01

    We report on the first measurements of the isotopic ratio {sup 14}N/{sup 15}N in N{sub 2}H{sup +} toward a statistically significant sample of high-mass star-forming cores. The sources belong to the three main evolutionary categories of the high-mass star formation process: high-mass starless cores, high-mass protostellar objects, and ultracompact H ii regions. Simultaneous measurements of the {sup 14}N/{sup 15}N ratio in CN have been made. The {sup 14}N/{sup 15}N ratios derived from N{sub 2}H{sup +} show a large spread (from ∼180 up to ∼1300), while those derived from CN are in between the value measured in the terrestrial atmosphere (∼270) and that of the proto-solar nebula (∼440) for the large majority of the sources within the errors. However, this different spread might be due to the fact that the sources detected in the N{sub 2}H{sup +} isotopologues are more than those detected in the CN ones. The {sup 14}N/{sup 15}N ratio does not change significantly with the source evolutionary stage, which indicates that time seems to be irrelevant for the fractionation of nitrogen. We also find a possible anticorrelation between the {sup 14}N/{sup 15}N (as derived from N{sub 2}H{sup +}) and the H/D isotopic ratios. This suggests that {sup 15}N enrichment could not be linked to the parameters that cause D enrichment, in agreement with the prediction by recent chemical models. These models, however, are not able to reproduce the observed large spread in {sup 14}N/{sup 15}N, pointing out that some important routes of nitrogen fractionation could be still missing in the models.

  9. 1H, 13C and 15N resonance assignments and secondary structures of cyclophilin 2 from Trichomonas vaginalis.

    Science.gov (United States)

    Martin, Tesmine; Lou, Yuan-Chao; Aryal, Sarita; Tai, Jung-Hsiang; Chen, Chinpan

    2017-09-05

    Cyclophilins are peptidyl prolyl isomerases that play an important role in a wide variety of biological functions like protein folding and trafficking, intracellular and extracellular signaling pathways, nuclear translocation and in pre-mRNA splicing. Two cyclophilins have been identified in the parasitic organism Trichomonas vaginalis and were named as TvCyP1 and TvCyP2. The 2 enzymes have been found to interact with Myb transcription factors in the parasite which regulate the iron induced expression of ap65-1 gene leading to cytoadherence of the parasite to human vaginal epithelial cells to cause the disease trichomoniasis. TvCyP2 was found to interact specifically with Myb3 to regulate nuclear translocation of the transcription factor. It would be intriguing to identify the binding site of both proteins as it could pave way to newer targets for drug discovery. Here we report the 1H, 13C and 15N resonance assignments and secondary structure information of TvCyP2 that could help us investigate the interaction between Myb3 and TvCyP2 in detail using NMR.

  10. New Insights on the Nitrogen Footprint of a Coastal Megalopolis from Coral-Hosted Symbiodinium δ(15)N.

    Science.gov (United States)

    Wong, C W Martin; Duprey, Nicolas N; Baker, David M

    2017-02-21

    The development of megalopolises in coastal areas is often linked with severe eutrophication, requiring mitigation of anthropogenic dissolved inorganic nitrogen (DIN) pollution. Yet, identifying the DIN-sources responsible for eutrophication is challenging, hampering mitigation efforts. Here, we utilize the stable nitrogen isotope ratio of endosymbiotic dinoflagellate Symbiodinium spp. (δ(15)Nsym) associated with the hard coral Porites to trace DIN sources in one of the most urbanized areas of the planet: the Pearl River Delta (PRD). The mean δ(15)Nsym value found in the coastal waters of Hong Kong (HK), located on the eastern edge of the PRD, (7.4‰ ± 1.2‰) was +2.7‰ higher than at Dongsha Atoll, a reference site unaffected by anthropogenic-DIN (4.7‰ ± 0.4‰). The isotopic enrichment suggested a consistent dominance of DIN deriving from local and regional sewage discharges on the eastern edge of HK. Furthermore, the strong depletion of the summer δ(15)Nsym value (-1.6‰) observed in southern HK revealed that the Pearl River plume strongly modulates the coastal DIN pool. Our results revealed the value of benthic marine organisms' δ(15)N for deciphering the complex dynamics of coastal eutrophication and highlighted the pivotal role of transboundary coordination in DIN-pollution mitigation.

  11. Preparation of protic ionic liquids with minimal water content and (15)N NMR study of proton transfer.

    Science.gov (United States)

    Burrell, Geoffrey L; Burgar, Iko M; Separovic, Frances; Dunlop, Noel F

    2010-02-21

    Low-molecular-weight Brønsted acids and amine bases were used to reproducibly prepare very dry, high-purity room-temperature protic ionic liquids (PILs). A series of eight amine bases and six Brønsted acids were combined to produce 48 mixtures, of which 18 were liquid at room temperature. The phase transitions and thermal decomposition temperatures were determined for each mixture; whereas viscosity, density and conductivity were determined for the room-temperature liquids. By utilising (15)N NMR it was possible to distinguish between neutral and ionised amine bases (ammonia vs. ammonium-type ion), which indicated that the protic ionic liquids were completely ionised when made as a stoichiometric mixture. However, a Walden plot comparison of fluidity and molar conductivity indicated the majority of PILs had much lower conductivity than predicted by viscosity unless the base contained excess proton-donating groups. This disparity is indicative of protic ionic molecules forming neutral aggregates or non-Newtonian fluid hydrogen-bonded networks with a secondary Grotthuss proton-hopping mechanism arising from polyprotic bases.

  12. Comparison of two models in the estimation of nitrogen uptake rates using data from 15-N incubation experiments

    Directory of Open Access Journals (Sweden)

    Clavery Tungaraza

    2005-09-01

    Full Text Available This paper compares two uptake rate models, Dugdale & Goering's (D&G model and Elskens' model. The aim is to provide an insight into how estimates of uptake processes, i.e. regeneration and loss rates from both dissolved and particulate nitrogen pools, influence the total uptake rates when the two models are compared. The uptake rates of three nitrogenous nutrients (nitrate, ammonium and urea from 15-N incubation experimental data were compared. The comparison indicated that the D&G model underestimated nitrate uptake rates by about 34%, implying a significant regeneration and loss rates of the nutrient. Elskens' model further showed that the loss rates from the dissolved phase were about 40% and 25% for the ammonium and urea pools, respectively, indicating that the D&G model underestimated the experimental uptake rates of the nutrients. On average, nitrification made up about 30% of the total ammonium uptake flux, whereas the sinks from particulate nitrogen and dissolved nitrogen were estimated at 36% and 56%, respectively. The D&G model sometimes overestimated the f-ratio values to about 60% and higher as a result of ammonium and urea uptake rates underestimation. This paper also shows that detritus adsorption, bacterial uptake and cell lysis are equally important processes.

  13. Plant uptake of dual-labeled organic N biased by inorganic C uptake

    DEFF Research Database (Denmark)

    Rasmussen, Jim; Sauheitl, Leopold; Eriksen, Jørgen

    2010-01-01

    labeling experiment (15N + 13C + 14C) investigating whether root uptake of labeled inorganic C can bias the results obtained in studies of organic N uptake using dual-labeled amino acids (15N, 13C). In a rhizosphere tube experiment we investigated 13C and 14C uptake by maize either supplied with labeled...... glycine or CO2-3 , but found no differences in uptake rates between these C-sources. The uptake of inorganic C to the shoot tissue was higher for maize grown in full light compared to shading, which indicates a passive uptake of inorganic C with water. We conclude that uptake of inorganic C produced...... by mineralization of amino acids can significantly bias the interpretations of organic N uptake studies using dual-labeling....

  14. Phytoplankton trapped within seagrass (Posidonia oceanica) sediments are a nutrient source: An in situ isotope labeling experiment

    NARCIS (Netherlands)

    Barron, C.; Middelburg, J.J.; Duarte, C.M.

    2006-01-01

    We examined the retention of nitrogen associated with sedimented planktonic material trapped within a Mediterranean seagrass (Posidonia oceanica) meadow with the use of 15N-enriched algal material injected into vegetated and nonvegetated sediment as a tracer. The retention of labeled nitrogen

  15. Biosynthesis and characterization of ¹⁵N₆-labeled phomopsin A, a lupin associated mycotoxin produced by Diaporthe toxica.

    Science.gov (United States)

    Schloß, Svenja; Wedell, Ines; Koch, Matthias; Rohn, Sascha; Maul, Ronald

    2015-06-15

    The hepatotoxin phomopsin A (PHO-A), a secondary metabolite mainly produced by the fungus Diaporthe toxica, occurs predominantly on sweet lupins. Along with the growing interest in sweet lupins for food and feed commodities, concerns have been raised about fungal infestations, and consequently, about the determination of PHO-A. High performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) represents the most suitable analytical technique for sensitive and selective detection of mycotoxins including PHO-A. However, isotopic labeled substances are needed as internal standards for a reliable and convenient quantification. As no isotope standard for PHO-A is currently available, a biosynthesis of fully (15)N6-labeled PHO-A was established by cultivation of D. toxica on defined media containing Na(15)NO3 and (15)N-labeled yeast extract as the only nitrogen sources. The identity of (15)N6-PHO-A was confirmed by high resolution mass spectrometry. The new (15)N6-labeled standard will facilitate the method development for PHO-A including a more accurate quantification by LC-MS/MS. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Elucidating the Structures of the Low- and High-pH Mo(V) Species in Respiratory Nitrate Reductase: A Combined EPR, 14,15N HYSCORE, and DFT Study.

    Science.gov (United States)

    Rendon, Julia; Biaso, Frédéric; Ceccaldi, Pierre; Toci, René; Seduk, Farida; Magalon, Axel; Guigliarelli, Bruno; Grimaldi, Stéphane

    2017-04-17

    Respiratory nitrate reductases (Nars), members of the prokaryotic Mo/W-bis Pyranopterin Guanosine dinucleotide (Mo/W-bisPGD) enzyme superfamily, are key players in nitrate respiration, a major bioenergetic pathway widely used by microorganisms to cope with the absence of dioxygen. The two-electron reduction of nitrate to nitrite takes place at their active site, where the molybdenum ion cycles between Mo(VI) and Mo(IV) states via a Mo(V) intermediate. The active site shows two distinct pH-dependent Mo(V) electron paramagnetic resonance (EPR) signals whose structure and catalytic relevance have long been debated. In this study, we use EPR and HYSCORE techniques to probe their nuclear environment in Escherichia coli Nar (EcNar). By using samples prepared at different pH and through different enrichment strategies in 98Mo and 15N nuclei, we demonstrate that each of the two Mo(V) species is coupled to a single nitrogen nucleus with similar quadrupole characteristics. Structure-based density functional theory calculations allow us to propose a molecular model of the low-pH Mo(V) species consistent with EPR spectroscopic data. Our results show that the metal ion is coordinated by a monodentate aspartate ligand and permit the assignment of the coupled nitrogen nuclei to the Nδ of Asn52, a residue located ∼3.9 Å to the Mo atom in the crystal structures. This is confirmed by measurements on selectively 15N-Asn labeled EcNar. Further, we propose a Mo-O(H)···HN structure to account for the transfer of spin density onto the interacting nitrogen nucleus deduced from HYSCORE analysis. This work provides a foundation for monitoring the structure of the molybdenum active site in the presence of various substrates or inhibitors in Nars and other molybdenum enzymes.

  17. Fishing for ecosystem services

    Science.gov (United States)

    Pope, Kevin L.; Pegg, Mark A.; Cole, Nicholas W.; Siddons, Stephen F.; Fedele, Alexis D.; Harmon, Brian S.; Ruskamp, Ryan L.; Turner, Dylan R.; Uerling, Caleb C.

    2016-01-01

    Ecosystems are commonly exploited and manipulated to maximize certain human benefits. Such changes can degrade systems, leading to cascading negative effects that may be initially undetected, yet ultimately result in a reduction, or complete loss, of certain valuable ecosystem services. Ecosystem-based management is intended to maintain ecosystem quality and minimize the risk of irreversible change to natural assemblages of species and to ecosystem processes while obtaining and maintaining long-term socioeconomic benefits. We discuss policy decisions in fishery management related to commonly manipulated environments with a focus on influences to ecosystem services. By focusing on broader scales, managing for ecosystem services, and taking a more proactive approach, we expect sustainable, quality fisheries that are resilient to future disturbances. To that end, we contend that: (1) management always involves tradeoffs; (2) explicit management of fisheries for ecosystem services could facilitate a transition from reactive to proactive management; and (3) adaptive co-management is a process that could enhance management for ecosystem services. We propose adaptive co-management with an ecosystem service framework where actions are implemented within ecosystem boundaries, rather than political boundaries, through strong interjurisdictional relationships.

  18. Fishing for ecosystem services.

    Science.gov (United States)

    Pope, Kevin L; Pegg, Mark A; Cole, Nicholas W; Siddons, Stephen F; Fedele, Alexis D; Harmon, Brian S; Ruskamp, Ryan L; Turner, Dylan R; Uerling, Caleb C

    2016-12-01

    Ecosystems are commonly exploited and manipulated to maximize certain human benefits. Such changes can degrade systems, leading to cascading negative effects that may be initially undetected, yet ultimately result in a reduction, or complete loss, of certain valuable ecosystem services. Ecosystem-based management is intended to maintain ecosystem quality and minimize the risk of irreversible change to natural assemblages of species and to ecosystem processes while obtaining and maintaining long-term socioeconomic benefits. We discuss policy decisions in fishery management related to commonly manipulated environments with a focus on influences to ecosystem services. By focusing on broader scales, managing for ecosystem services, and taking a more proactive approach, we expect sustainable, quality fisheries that are resilient to future disturbances. To that end, we contend that: (1) management always involves tradeoffs; (2) explicit management of fisheries for ecosystem services could facilitate a transition from reactive to proactive management; and (3) adaptive co-management is a process that could enhance management for ecosystem services. We propose adaptive co-management with an ecosystem service framework where actions are implemented within ecosystem boundaries, rather than political boundaries, through strong interjurisdictional relationships. Published by Elsevier Ltd.

  19. Dynamics of δ(15)N isotopic signatures of different intertidal macroalgal species: Assessment of bioindicators of N sources in coastal areas.

    Science.gov (United States)

    Lemesle, Stéphanie; Erraud, Alexandre; Mussio, Isabelle; Rusig, Anne-Marie; Claquin, Pascal

    2016-09-15

    δ(15)N of annual (Ulva sp., Porphyra sp.) and perennial intertidal seaweed species (Chondrus crispus, Fucus sp.) collected on 17 sampling points along the French coast of the English Channel in 2012 and 2013 were assessed on their suitability as bioindicators of N pollution in coastal areas. A sine function applied for δ(15)N time series data showed for all the species the same seasonal trend with lowest δ(15)N values in April and highest in summer but with no significant interspecific differences of amplitude (α) and phase angle (ϕ). This model provides a useful tool for monitoring the inter-annual changes of N pollution. An interspecific variability of δ(15)N values was observed, probably due to their tolerance to emersion. An in vitro study for comparing the kinetic acquisition of the isotopic signal and N uptake mechanisms of each species underlined the influence of algal physiology on the δ(15)N interspecific variability. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. δ(15)N variation in Ulva lactuca as a proxy for anthropogenic nitrogen inputs in coastal areas of Gulf of Gaeta (Mediterranean Sea).

    Science.gov (United States)

    Orlandi, Lucia; Bentivoglio, Flavia; Carlino, Pasquale; Calizza, Edoardo; Rossi, David; Costantini, Maria Letizia; Rossi, Loreto

    2014-07-15

    We tested the capacity of Ulva lactuca to mark N sources across large marine areas by measuring variation in its δ(15)N at several sites in the Gulf of Gaeta. Comparisons were made with the macroalga Cystoseira amentacea. Variation of δ(15)N values was assessed also in the coastal waters off the Circeo Natural Park, where U. lactuca and C. amentacea were harvested, as these waters are barely influenced by human activities and were used as reference site. A small fragment from each frond was preserved before deployment in order to characterize the initial isotopic values. After 48 h of submersion, U. lactuca was more responsive than C. amentacea to environmental variation and δ(15)N enrichment in the Gulf of Gaeta was observed. The spatial distribution of δ(15)N enrichment indicated that different macro-areas in the Gulf were affected by N inputs from different origins. Comparison of the δ(15)N values of fragments taken from the same transplanted frond avoided bias arising from natural isotopic variability. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Columbia River Estuary Ecosystem Classification Ecosystem Complex

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Estuarine ecosystems are controlled by a variety of processes that operate at multiple spatial and temporal scales. Understanding the hierarchical nature of these...

  2. Defining fish community structure in Lake Winnipeg using stable isotopes (δ{sup 13}C, δ{sup 15}N, δ{sup 34}S): Implications for monitoring ecological responses and trophodynamics of mercury and other trace elements

    Energy Technology Data Exchange (ETDEWEB)

    Ofukany, Amy F.A. [Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3 (Canada); Wassenaar, Leonard I. [Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5 (Canada); Bond, Alexander L., E-mail: alex.bond@rspb.org.uk [Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5 (Canada); Hobson, Keith A. [Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5 (Canada)

    2014-11-01

    The ecological integrity of freshwater lakes is influenced by atmospheric and riverine deposition of contaminants, shoreline development, eutrophication, and the introduction of non-native species. Changes to the trophic structure of Lake Winnipeg, Canada, and consequently, the concentrations of contaminants and trace elements measured in tissues of native fishes, are likely attributed to agricultural runoff from the 977,800 km{sup 2} watershed and the arrival of non-native zooplankters and fishes. We measured δ{sup 13}C, δ{sup 15}N, and δ{sup 34}S along with concentrations of 15 trace elements in 17 native fishes from the north and south basins of Lake Winnipeg in 2009 and 2010. After adjusting for differences in isotopic baseline values between the two basins, fishes in the south basin had consistently higher δ{sup 13}C and δ{sup 34}S, and lower δ{sup 15}N. We found little evidence of biomagnification of trace elements at the community level, but walleye (Sander vitreus) and freshwater drum (Aplodinotus grunniens) had higher mercury and selenium concentrations with increased trophic position, coincident with increased piscivory. There was evidence of growth dilution of cobalt, copper, manganese, molybdenum, thallium, and vanadium, and bioaccumulation of mercury, which could be explained by increases in algal (and consequently, lake and fish) productivity. We conclude that the north and south basins of Lake Winnipeg represent very different communities with different trophic structures and trace element concentrations. - Highlights: • Anthropogenic eutrophication and non-native species affect Lake Winnipeg’s ecosystem. • We measured stable isotopes and trace elements in 15 native fish species. • There was more evidence for growth dilution than biomagnification for most elements. • The trophic structures of the north and south basins were different. • These results will help determine the effects of recent arrival of zebra mussels.

  3. Food Label and You

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    Full Text Available ... Español Search FDA Submit search Popular Content Home Food Drugs Medical Devices Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Food Home Food Ingredients, Packaging & Labeling Labeling & Nutrition The Food ...

  4. Edge colouring by total labellings

    DEFF Research Database (Denmark)

    Brandt, Stephan; Rautenbach, D.; Stiebitz, M.

    2010-01-01

    We introduce the concept of an edge-colouring total k-labelling. This is a labelling of the vertices and the edges of a graph G with labels 1, 2, ..., k such that the weights of the edges define a proper edge colouring of G. Here the weight of an edge is the sum of its label and the labels of its...

  5. Seasonal changes in the δ13C and δ15N signatures of the Lago Maggiore pelagic food web

    Directory of Open Access Journals (Sweden)

    Marina MANCA

    2011-08-01

    Full Text Available Seasonal variation in the relative contributions of littoral and pelagic food sources to the diets of open-water zooplankton and subsequent changes in their trophic positions were investigated with carbon and nitrogen Stable Isotope Analysis (SIA. We selected three open water stations as truly pelagic, but also influenced by littoral and riverine carbon sources. During each of the four seasons, integrated pelagic zooplankton samples were collected over 0-50 m depth intervals at each site along with seston in the size range 1.2-76 μm. In addition, vertical temperature profiles were measured. Littoral benthos from three sites along the main longitudinal axis of the lake was sampled to serve as a reference for tracing Lago Maggiore's littoral carbon isotopic signature. Among stations differences in δ13C and δ15N signatures of the different components of the pelagic food web, from seston to predatory zooplankton, were statistically non significant, thus confirming that allochthonous input may become important only after exceptional rainfall events. Changes in the δ13C pelagic baseline mirrored mean water temperature (0-50 m seasonal changes. Similarly to Lake Geneva, they were likely driven by changes in carbon sources for phytoplankton growth during stratification and vertical water mixing. Differently from what observed for the other taxa, the role of littoral food sources was far from negligible (>50% for diaptomids during winter and spring. We do not know however, whether such a result could be at least partially attributed to the heavy infestation by algal epibionts, or was consequent to the fact that these zooplankters may carry littoral carbon to the pelagial via horizontal migration. In winter, Bythotrephes longimanus was able to prey on Cyclops, thus occupying a trophic position comparable to that of planktivorous fish. Such a result confirms an ability of this visual, invertebrate predator to compete with young zooplanktivorous fish

  6. Practical considerations for investigation of protein conformational dynamics by {sup 15}N R{sub 1ρ} relaxation dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Walinda, Erik [Kyoto University, Department of Molecular and Cellular Physiology, Graduate School of Medicine (Japan); Morimoto, Daichi; Shirakawa, Masahiro; Sugase, Kenji, E-mail: sugase@moleng.kyoto-u.ac.jp [Kyoto University, Department of Molecular Engineering, Graduate School of Engineering (Japan)

    2017-03-15

    It is becoming increasingly apparent that proteins are not static entities and that their function often critically depends on accurate sampling of multiple conformational states in aqueous solution. Accordingly, the development of methods to study conformational states in proteins beyond their ground-state structure (“excited states”) has crucial biophysical importance. Here we investigate experimental schemes for optimally probing chemical exchange processes in proteins on the micro- to millisecond timescale by {sup 15}N R{sub 1ρ} relaxation dispersion. The schemes use selective Hartmann–Hahn cross-polarization (CP) transfer for excitation, and derive peak integrals from 1D NMR spectra (Korzhnev et al. in J Am Chem Soc 127:713–721, 2005; Hansen et al. in J Am Chem Soc 131:3818–3819, 2009). Simulation and experiment collectively show that in such CP-based schemes care has to be taken to achieve accurate suppression of undesired off-resonance coherences, when using weak spin-lock fields. This then (i) ensures that relaxation dispersion profiles in the absence of chemical exchange are flat, and (ii) facilitates extraction of relaxation dispersion profiles in crowded regions of the spectrum. Further improvement in the quality of the experimental data is achieved by recording the free-induction decays in an interleaved manner and including a heating-compensation element. The reported considerations will particularly benefit the use of CP-based R{sub 1ρ} relaxation dispersion to analyze conformational exchange processes in larger proteins, where resonance line overlap becomes the main limiting factor.

  7. Using 15N, 17O, and 18O to determine nitrate sources in the Yellow River, China.

    Science.gov (United States)

    Liu, Ting; Wang, Fan; Michalski, Greg; Xia, Xinghui; Liu, Shaoda

    2013-01-01

    Many previous studies have used δ(15)N and δ(18)O of nitrate (δ(15)NNO3 and δ(18)ONO3) to determine the nitrate sources in rivers but were subject to substantial uncertainties and limitations, especially associated with evaluating the atmospheric contribution. The Δ(17)O of nitrate (Δ(17)ONO3) has been suggested as an unambiguous tracer of atmospheric NO3(-) and may serve as an additional nitrate source constraint. In the present study, triple nitrate isotopes (δ(15)NNO3, Δ(17)ONO3, and δ(18)ONO3) were used for the first time to assess the sources and sinks of nitrate in the Yellow River (YR) basin, which is the second longest river in China. Results showed that the Δ(17)ONO3 of the water from the YR ranged from 0‰ to 1.6‰ during two normal-water seasons. This suggested that unprocessed atmospheric nitrate accounted for 0-7% of the total nitrate in the YR. The corrected δ(15)NNO3 and δ(18)ONO3 values with atmospheric imprints being removed indicated that the main terrestrial sources of nitrate were sewage/manure effluents in the upstream of the YR and manure/sewage effluents and ammonium/urea-containing fertilizer in the middle and lower reaches which made comparable contributions to the nitrate. In addition, there was a significant positive relationship between δ(15)NNO3 and δ(18)ONO3 values of river water (p nitrate isotope method is useful for assessing the nitrate sources in rivers, especially for the measurements of atmospheric nitrate contribution.

  8. Real-time pure shift {sup 15}N HSQC of proteins: a real improvement in resolution and sensitivity

    Energy Technology Data Exchange (ETDEWEB)

    Kiraly, Peter; Adams, Ralph W.; Paudel, Liladhar; Foroozandeh, Mohammadali [University of Manchester, School of Chemistry (United Kingdom); Aguilar, Juan A. [Durham University, Department of Chemistry (United Kingdom); Timári, István [University of Debrecen, Department of Inorganic and Analytical Chemistry (Hungary); Cliff, Matthew J. [University of Manchester, Manchester Institute of Biotechnology (United Kingdom); Nilsson, Mathias [University of Manchester, School of Chemistry (United Kingdom); Sándor, Péter [Agilent Technologies R& D and Marketing GmbH & Co. KG (Germany); Batta, Gyula [University of Debrecen, Department of Organic Chemistry (Hungary); Waltho, Jonathan P. [University of Manchester, Manchester Institute of Biotechnology (United Kingdom); Kövér, Katalin E. [University of Debrecen, Department of Inorganic and Analytical Chemistry (Hungary); Morris, Gareth A., E-mail: g.a.morris@manchester.ac.uk [University of Manchester, School of Chemistry (United Kingdom)

    2015-05-15

    Spectral resolution in proton NMR spectroscopy is reduced by the splitting of resonances into multiplets due to the effect of homonuclear scalar couplings. Although these effects are often hidden in protein NMR spectroscopy by low digital resolution and routine apodization, behind the scenes homonuclear scalar couplings increase spectral overcrowding. The possibilities for biomolecular NMR offered by new pure shift NMR methods are illustrated here. Both resolution and sensitivity are improved, without any increase in experiment time. In these experiments, free induction decays are collected in short bursts of data acquisition, with durations short on the timescale of J-evolution, interspersed with suitable refocusing elements. The net effect is real-time (t{sub 2}) broadband homodecoupling, suppressing the multiplet structure caused by proton–proton interactions. The key feature of the refocusing elements is that they discriminate between the resonances of active (observed) and passive (coupling partner) spins. This can be achieved either by using band-selective refocusing or by the BIRD element, in both cases accompanied by a nonselective 180° proton pulse. The latter method selects the active spins based on their one-bond heteronuclear J-coupling to {sup 15}N, while the former selects a region of the {sup 1}H spectrum. Several novel pure shift experiments are presented, and the improvements in resolution and sensitivity they provide are evaluated for representative samples: the N-terminal domain of PGK; ubiquitin; and two mutants of the small antifungal protein PAF. These new experiments, delivering improved sensitivity and resolution, have the potential to replace the current standard HSQC experiments.

  9. Intraspecific variation in hair delta(13)C and delta(15)N values of ring-tailed lemurs (Lemur catta) with known individual histories, behavior, and feeding ecology.

    Science.gov (United States)

    Loudon, James E; Sponheimer, Matt; Sauther, Michelle L; Cuozzo, Frank P

    2007-07-01

    Stable carbon and nitrogen isotope compositions were analyzed from hair samples of 30 sympatric ring-tailed lemurs (Lemur catta) inhabiting the Beza Mahafaly Special Reserve, Madagascar. All lemurs were known individuals involved in a longitudinal study, which allowed us to explore the degree to which group membership, sex, health status, and migration influenced their stable isotope compositions. The differences in delta(13)C and delta(15)N values between groups were small (lemur conservation. There were few sex differences, but significant differences did occur between individuals of normal and suboptimal health, with those in poor health (especially those in the worst condition) being enriched in (15)N and to a lesser degree (13)C compared with healthy individuals. Moreover, lemurs that had emigrated between 2003 and 2004 had different delta(13)C and delta(15)N compositions than their original groups. (c) 2007 Wiley-Liss, Inc.

  10. Soil and foliar nutrient and nitrogen isotope composition (δ(15)N) at 5 years after poultry litter and green waste biochar amendment in a macadamia orchard.

    Science.gov (United States)

    Bai, Shahla Hosseini; Xu, Cheng-Yuan; Xu, Zhihong; Blumfield, Timothy J; Zhao, Haitao; Wallace, Helen; Reverchon, Frédérique; Van Zwieten, Lukas

    2015-03-01

    This study aimed to evaluate the improvement in soil fertility and plant nutrient use in a macadamia orchard following biochar application. The main objectives of this study were to assess the effects of poultry litter and green waste biochar applications on nitrogen (N) cycling using N isotope composition (δ(15)N) and nutrient availability in a soil-plant system at a macadamia orchard, 5 years following application. Biochar was applied at 10 t ha(-1) dry weight but concentrated within a 3-m diameter zone when trees were planted in 2007. Soil and leaf samples were collected in 2012, and both soil and foliar N isotope composition (δ(15)N) and nutrient concentrations were assessed. Both soil and foliar δ(15)N increased significantly in the poultry litter biochar plots compared to the green waste biochar and control plots. A significant relationship was observed between soil and plant δ(15)N. There was no influence of either biochars on foliar total N concentrations or soil NH4 (+)-N and NO3 (-)-N, which suggested that biochar application did not pose any restriction for plant N uptake. Plant bioavailable phosphorus (P) was significantly higher in the poultry litter biochar treatment compared to the green waste biochar treatment and control. We hypothesised that the bioavailability of N and P content of poultry litter biochar may play an important role in increasing soil and plant δ(15)N and P concentrations. Biochar application affected soil-plant N cycling and there is potential to use soil and plant δ(15)N to investigate N cycling in a soil-biochar-tree crop system. The poultry litter biochar significantly increased soil fertility compared to the green waste biochar at 5 years following biochar application which makes the poultry litter a better feedstock to produce biochar compared to green waste for the tree crops.

  11. Accounting for the effects of lipids in stable isotope (δ13C and δ15N values) analysis of skin and blubber of balaenopterid whales.

    Science.gov (United States)

    Ryan, Conor; McHugh, Brendan; Trueman, Clive N; Harrod, Chris; Berrow, Simon D; O'Connor, Ian

    2012-12-15

    Stable isotope values (δ(13)C and δ(15)N) of darted skin and blubber biopsies can shed light on habitat use and diet of cetaceans, which are otherwise difficult to study. Non-dietary factors affect isotopic variability, chiefly the depletion of (13)C due to the presence of (12)C-rich lipids. The efficacy of post hoc lipid-correction models (normalization) must be tested. For tissues with high natural lipid content (e.g., whale skin and blubber), chemical lipid extraction or normalization is necessary. C:N ratios, δ(13)C values and δ(15)N values were determined for duplicate control and lipid-extracted skin and blubber of fin (Balaenoptera physalus), humpback (Megaptera novaeangliae) and minke whales (B. acutorostrata) by continuous-flow elemental analysis isotope ratio mass spectrometry (CF-EA-IRMS). Six different normalization models were tested to correct δ(13)C values for the presence of lipids. Following lipid extraction, significant increases in δ(13)C values were observed for both tissues in the three species. Significant increases were also found for δ(15)N values in minke whale skin and fin whale blubber. In fin whale skin, the δ(15)N values decreased, with no change observed in humpback whale skin. Non-linear models generally out-performed linear models and the suitability of models varied by species and tissue, indicating the need for high model specificity, even among these closely related taxa. Given the poor predictive power of the models to estimate lipid-free δ(13)C values, and the unpredictable changes in δ(15)N values due to lipid-extraction, we recommend against arithmetical normalization in accounting for lipid effects on δ(13)C values for balaenopterid skin or blubber samples. Rather, we recommend that duplicate analysis of lipid-extracted (δ(13)C values) and non-treated tissues (δ(15)N values) be used. Copyright © 2012 John Wiley & Sons, Ltd.

  12. Nutrient dynamics and oceanographic features in the central Namibian upwelling region as reflected in δ15N-signals of suspended matter and surface sediments

    Directory of Open Access Journals (Sweden)

    S. Meisel

    2011-08-01

    Full Text Available The study deals with the modern situation of the northern Benguela Upwelling, directing particular attention to the shelf region off central Namibia (21 to 24° S. At the centre of the investigation is the comparison of δ15N-records in surface sediments (δ15Nsediment with suspended particulate matter (δ15NSPM from the surface ocean. In addition to that, water column profiles (including hydrographic data provide an insight into changes of δ15NSPM with depth and elucidate potential offsets between δ15NSPM and δ15Nsediment. The parallel spatial trend of δ15Nsediment and surface ocean δ15NSPM shows that secondary processes are not so pronounced as to obliterate the signal generated in the surface waters. Highest δ15N-signatures are found right off the coast where water temperatures are lowest. Concomitantly high productivity rates and low bottom oxygen suggest the upwelling of denitrified source waters. With increasing distance offshore, δ15N declines unexpectedly, reaching a minimum above the shelf break. Beyond that, the trend reverses to "normal" with δ15N-signals continuously increasing towards the mesopelagic ocean. The decrease in δ15Nsediment and surface ocean δ15NSPM with increasing distance to the coast disagrees with the concept of Rayleigh fractionation kinetics, viz. the progressive 15N-enrichment of the nitrate pool as it is gradually used up by phytoplankton growth. On the basis of the available evidence, the downward trend of δ15N results from decreased relative nitrate consumption, resting on a combination of reduced primary production and the existence of an ulterior source of nutrients. Nutrient replenishment seems to occur via an additional upwelling front at the edge of the shelf as well as tapping of subsurface nitrate through sufficiently deep penetration of wind- and wave-induced mixing over large areas of the shelf. Both mechanisms are considered capable of working against the expected nutrient drawdown (i.e. 15

  13. 12C/13C and 14N/15N isotopic ratios in HCN in the middle atmosphere of Titan from Cassini/CIRS data

    Science.gov (United States)

    Mathé, Christophe; Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2017-10-01

    Our study aims at constraining the 12C/13C and 14N/15N isotopic ratios in HCN, the most abundant nitrile in Titan’s atmosphere, which can provide information on physical and chemical process occurring during the formation and/or destruction of this molecule.Over the last decade, several estimations of the 12C/13C and 14N/15N isotopic ratios in HCN were performed from ground-based, Herschel and Cassini observations (Bézard et al,2014). The 14N/15N ratio lies in the range 56-76, which corresponds to half of the 14N/15N ratio in N2 (major N-bearing molecule in Titan’s atmosphere). This nitrogen isotopic fractionation mostly originates from the photodissociation of N2 (Liang et al, 2007). The 12C/13C ratio lies in the range 75-108, in agreement with the 12C/13C ratio in CH4 (major C-bearing molecule). Recent disk-averaged ALMA observations indicate 12C/13C and 14N/15N ratios equal to ˜90 and ˜72, respectively (Molter et al, 2016).Vinatier et al (2007) derived 14N/15N and 12C/13C ratios in two different regions (equator and north pole) from Cassini/CIRS (Composite InfraRed Spectrometer) observations at the beginning of the Cassini mission. 14N/15N was similar for both latitudes while the 12C/13C ratio displayed a possible enhancement at the equator.We present here a new study of the 12C/13C and 14N/15N isotopic ratios in HCN from CIRS. We analyzed limb observations (0.5 cm-1 resolution) from northern winter to early spring at poles, mid-latitudes and equator in order to investigate potential spatial and seasonal changes of these isotopic ratios in Titan’s middle atmosphere. These preliminary results will be presented and compared with previous observations.References:Bézard et al., Cambrigde University Press, 2014Liang et al., The Astrophysical Jounral Letters, 2007Molter et al., The Astronomical Journal, 2016Vinatier et al., Icarus, 2007

  14. Determination of δ13C, δ15N, or δ34S by isotope-ratio-monitoring mass spectrometry using an elemental analyzer

    Science.gov (United States)

    Johnson, Craig A.; Stricker, Craig A.; Gulbransen, Cayce A.; Emmons, Matthew P.

    2018-02-14

    This report describes procedures used in the Geology, Geophysics, and Geochemistry Science Center of the U.S. Geological Survey in Denver, Colorado, to determine the stable-isotope ratios 13C/12C, 15N/14N, and 34S/32S in solid materials. The procedures use elemental analyzers connected directly to gas-source isotope-ratio mass spectrometers. A different elemental–analyzer–mass-spectrometer system is used for 13C/12C and 15N/14N than is used for 34S/32S to accommodate differences in reagents, catalysts, and instrument settings.

  15. Dissolved organic matter uptake in a temperate seagrass ecosystem

    NARCIS (Netherlands)

    Van Engeland, T.; Bouma, T.J.; Morris, E.P.; Brun, F.G.; Peralta, G.; Lara, M.; Hendriks, I.E.; van Rijswijk, P.; Veuger, B.; Soetaert, K.; Middelburg, J.J.

    2013-01-01

    We assessed the utilization of inorganic and organic nitrogen compounds of different complexity by primary producers and bacteria in a seagrass ecosystem. Using double-labeled (C-13 and N-15) substrates, the net transfers from the dissolved nitrogen and carbon pools to phytoplankton, planktonic

  16. Diet shifts and population dynamics of estuarine foraminifera during ecosystem recovery after experimentally induced hypoxia crises

    NARCIS (Netherlands)

    Brouwer, G.M.; Duijnstee, Ivo; Hazeleger, J.H.; Rossi, F.; Lourens, L.J.; Middelburg, J.J.; Wolthers, M.

    2016-01-01

    This study shows foraminiferal dynamics after experimentally induced hypoxia within the wider context of ecosystem recovery. 13C-labeled bicarbonate and glucose were added to the sediments to examine foraminiferal diet shifts during ecosystem recovery and test-size measurements were used to deduce

  17. Capacitive label reader

    Science.gov (United States)

    Arlowe, H. Duane

    1985-01-01

    A capacitive label reader includes an outer ring transmitting portion, an inner ring transmitting portion, and a plurality of insulated receiving portions. A label is the mirror-image of the reader except that identifying portions corresponding to the receiving portions are insulated from only one of two coupling elements. Positive and negative pulses applied, respectively, to the two transmitting rings biased a CMOS shift register positively to either a 1 or 0 condition. The output of the CMOS may be read as an indication of the label.

  18. Natural 15N abundance of soil N pools and N2O reflect the nitrogen dynamics of forest soils

    DEFF Research Database (Denmark)

    Pörtl, K.; Zechmeister-Boltenstern, S.; Wanek, W.

    2007-01-01

    Natural N-15 abundance measurements of ecosystem nitrogen (N) pools and N-15 pool dilution assays of gross N transformation rates were applied to investigate the potential of delta N-15 signatures of soil N pools to reflect the dynamics in the forest soil N cycle. Intact soil cores were collected...... experiments provided a more complete picture of soil N dynamics than possible with either measurement done separately....... from pure spruce (Picea abies (L.) Karst.) and mixed spruce-beech (Fagus sylvatica L.) stands on stagnic gleysol in Austria. Soil delta N-15 values of both forest sites increased with depth to 50 cm, but then decreased below this zone. delta N-15 values of microbial biomass (mixed stand: 4.7 +/- 0...

  19. Probability distribution functions of δ15N and δ18O in groundwater nitrate to probabilistically solve complex mixing scenarios

    Science.gov (United States)

    Chrystal, A.; Heikoop, J. M.; Davis, P.; Syme, J.; Hagerty, S.; Perkins, G.; Larson, T. E.; Longmire, P.; Fessenden, J. E.

    2010-12-01

    Elevated nitrate (NO3-) concentrations in drinking water pose a health risk to the public. The dual stable isotopic signatures of δ15N and δ18O in NO3- in surface- and groundwater are often used to identify and distinguish among sources of NO3- (e.g., sewage, fertilizer, atmospheric deposition). In oxic groundwaters where no denitrification is occurring, direct calculations of mixing fractions using a mass balance approach can be performed if three or fewer sources of NO3- are present, and if the stable isotope ratios of the source terms are defined. There are several limitations to this approach. First, direct calculations of mixing fractions are not possible when four or more NO3- sources may be present. Simple mixing calculations also rely upon treating source isotopic compositions as a single value; however these sources themselves exhibit ranges in stable isotope ratios. More information can be gained by using a probabilistic approach to account for the range and distribution of stable isotope ratios in each source. Fitting probability density functions (PDFs) to the isotopic compositions for each source term reveals that some values within a given isotopic range are more likely to occur than others. We compiled a data set of dual isotopes in NO3- sources by combining our measurements with data collected through extensive literature review. We fit each source term with a PDF, and show a new method to probabilistically solve multiple component mixing scenarios with source isotopic composition uncertainty. This method is based on a modified use of a tri-linear diagram. First, source term PDFs are sampled numerous times using a variation of stratified random sampling, Latin Hypercube Sampling. For each set of sampled source isotopic compositions, a reference point is generated close to the measured groundwater sample isotopic composition. This point is used as a vertex to form all possible triangles between all pairs of sampled source isotopic compositions

  20. Dynamic belowground ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Harris, W. F.; Santantonio, D.; McGinty, D.

    1979-01-01

    Roots comprise the primary interface between plant and soil for uptake of water and nutrients. Much is known about the biochemistry, cell physiology and membrane physics associated with these important processes. In this paper we discuss the role of the belowground ecosystem, especially the autotrophic root component, in the structure and function of forest ecosystems. Beyond recognizing roles of anchoring terrestrial plants and uptake of water and nutrients, this component of the forest has been largely neglected in an ecosystem context. In order to focus discussion on the properties of the belowground ecosystem, we use the term rhizosphere to include roots, mycorrhizae, microbes, and rhizophagus invertebrates.

  1. Food Label and You

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    Full Text Available ... Sports show highlighting the importance of using the nutrition facts label to control portions, fat, calories and percent daily value. Two studio "sports announcers" describe the "game day" food action of ...

  2. FDA Online Label Repository

    Data.gov (United States)

    U.S. Department of Health & Human Services — The drug labels and other drug-specific information on this Web site represent the most recent drug listing information companies have submitted to the Food and Drug...

  3. Food Label and You

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    Full Text Available ... main page content Skip to search Skip to topics menu Skip to common links HHS U.S. Department ... a contestant in food label knowledge. Questions cover topics such as Calories, Serving Size, Servings per Container, ...

  4. Food Label and You

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    Full Text Available ... Video Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print NOTE: FDA has ... Finding Nutrition Information on the Road) Game Show Review (Are You Smarter Than A Food Label?) The ...

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    Full Text Available ... presents an entertaining and educational tool to help consumers understand and use the Nutrition Facts Label to ... Continuing Education Inspections & Compliance Federal, State & Local Officials Consumers Health Professionals Science & Research Industry Scroll back to ...

  6. Food Label and You

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    Full Text Available ... of a Sunday Afternoon Sports show highlighting the importance of using the nutrition facts label to control ... Site Map Nondiscrimination Website Policies U.S. Food and Drug Administration 10903 New Hampshire Avenue Silver Spring, MD ...

  7. Food Label and You

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    Full Text Available ... facts label to control portions, fat, calories and percent daily value. Two studio "sports announcers" describe the " ... 10903 New Hampshire Avenue Silver Spring, MD 20993 1-888-INFO-FDA (1-888-463-6332) Contact ...

  8. Food Labels Survey

    Science.gov (United States)

    ... Organic Food  Many consumers think federal standards for fish labeled ‘organic’ should require 100% organic feed (87%), ... used (82%), no added colors to the feed/fish (80%), or no open fish net farms (68%).  ...

  9. Food Label and You

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    Full Text Available ... of a Sunday Afternoon Sports show highlighting the importance of using the nutrition facts label to control ... Emergency Preparedness International Programs News & Events Training & Continuing Education Inspections & Compliance Federal, State & Local Officials Consumers Health ...

  10. Food Label and You

    Medline Plus

    Full Text Available ... Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Food Home Food Ingredients, Packaging & Labeling ... Radiation-Emitting Products Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products

  11. Metabolic labeling of plant cell cultures with K15NO3 as a tool for quantitative analysis of proteins and metabolites

    Directory of Open Access Journals (Sweden)

    Kopka Joachim

    2006-09-01

    Full Text Available Abstract Strategies for robust quantitative comparison between different biological samples are of high importance in experiments that address biological questions beyond the establishment of protein lists. Here, we propose the use of 15N-KNO3 as the only nitrogen source in Arabidopsis cell cultures in order to achieve a metabolically fully labeled cell population. Proteins from such metabolically labeled culture are distinguishable from unlabeled protein populations by a characteristic mass shift that depends on the amino acid composition of the tryptic peptide analyzed. In addition, the metabolically labeled cell extracts are also suitable for comparative quantitative analysis of nitrogen-containing cellular metabolic complement. Protein extracts from unlabeled and from standardized 15N-labeled cells were combined into one sample for joined analytical processing. This has the advantage of (i reduced experimental variability and (ii immediate relative quantitation at the level of single extracted peptide and metabolite spectra. Together ease and accuracy of relative quantitation for profiling experiments is substantially improved. The metabolic labeling strategy has been validated by mixtures of protein extracts and metabolite extracts from the same cell cultures in known ratios of labeled to unlabeled extracts (1:1, 1:4, and 4:1. We conclude that saturating metabolic 15N-labeling provides a robust and affordable integrative strategy to answer questions in quantitative proteomics and nitrogen focused metabolomics.

  12. BUSINESS ECOSYSTEMS VS BUSINESS DIGITAL ECOSYSTEMS

    Directory of Open Access Journals (Sweden)

    Marinela Lazarica

    2006-05-01

    Full Text Available E-business is often described as the small organisations’ gateway to global business and markets. The adoption of Internet-based technologies for e-business is a continuous process, with sequential steps of evolution. The latter step in the adoption of Internet-based technologies for business, where the business services and the software components are supported by a pervasive software environment, which shows an evolutionary and self-organising behaviour are named digital business ecosystems. The digital business ecosystems are characterized by intelligent software components and services, knowledge transfer, interactive training frameworks and integration of business processes and e-government models.

  13. Effects of lipid and urea extraction on δ15N values of deep-sea sharks and hagfish: Can mathematical correction factors be generated?

    Science.gov (United States)

    Churchill, Diana A.; Heithaus, Michael R.; Dean Grubbs, R.

    2015-05-01

    Stable isotope analysis is broadly employed to investigate diverse ecological questions. In order to make appropriate comparisons among multiple taxa, however, it is necessary to standardize values to account for interspecific differences in factors that affect isotopic ratios. For example, varying concentrations of soluble nitrogen compounds, such as urea or trimethylamine oxide, can affect the analysis and interpretation of δ15N values of sharks or hagfish. The goal of this study was to assess the effects of a standard chloroform/methanol extraction on the stable isotope values of muscle tissue obtained from 10 species of sharks and three species of hagfish collected from poorly-known deep-water (>200 m) communities. We detected significant differences in δ15N, %N, and C:N values as a result of extractions in 8 of 10 shark and all three hagfish species. We observed increased δ15N values, but shifts in %N and C:N values were not unidirectional. Mathematical normalizations for δ15N values were successfully created for four shark and two hagfish species. However, they were not successful for two shark species. Therefore, performing extractions of all samples is recommended.

  14. 1H, 13C and 15N NMR assignments of an unusual Ca2+-binding protein from Entamoeba histolytica in its apo form.

    Science.gov (United States)

    Verma, Deepshikha; Sakuntala, Mutyala; Murmu, Aruna; Bhattacharya, Alok; Chary, Kandala V R

    2017-04-01

    We report almost complete sequence specific 1H, 13C and 15N NMR assignments of an unusual Ca2+-binding protein from Entamoeba histolytica (EhCaBP6) in its apo form as a prelude to its structural and functional characterization.

  15. Anthropogenic nitrogen input traced by means of {delta} {sup 15}N values in macroalgae: Results from in-situ incubation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, Barbara [Baltic Sea Research Institute, Seestr. 15, 18119 Rostock (Germany)]. E-mail: barbara.deutsch@io-warnemuende.de; Voss, Maren [Baltic Sea Research Institute, Seestr. 15, 18119 Rostock (Germany)

    2006-08-01

    The macroalgae species Fucus vesiculosus (Phaeophyta), Polysiphonia sp., and Ceramium rubrum (Rhodophyta) originally grown at an unpolluted brackish site of the southern Baltic Sea were incubated for 10 and 14 days at 12 stations along a salinity gradient in a highly polluted estuary. We have expected an adaptation of the initially low {delta} {sup 15}N values to the higher ones within the incubation period. In addition to the m