Science.gov

Sample records for natural abundance 13c

  1. High-resolution magic-angle spinning (13)C spectroscopy of brain tissue at natural abundance.

    PubMed

    Yang, Yongxia; Chen, Lei; Gao, Hongchang; Zeng, Danlin; Yue, Yong; Liu, Maili; Lei, Hao; Deng, Feng; Ye, Chaohui

    2006-03-01

    High-resolution magic-angle spinning (MAS) (1)H and (13)C magnetic resonance spectroscopy (MRS) has recently been applied to study the metabolism in intact biological tissue samples. Because of the low natural abundance and the low gyromagnetic ratio of the (13)C nuclei, signal enhancement techniques such as cross-polarization (CP) and distortionless enhancement by polarization transfer (DEPT) are often employed in MAS (13)C MRS to improve the detection sensitivity. In this study, several sensitivity enhancement techniques commonly used in liquid- and solid-state NMR, including CP, DEPT and nuclear Overhauser enhancement (NOE), were combined with MAS to acquire high-resolution (13)C spectra on intact rat brain tissue at natural abundance, and were compared for their performances. The results showed that different signal enhancement techniques are sensitive to different classes of molecules/metabolites, depending on their molecular weights and mobility. DEPT was found to enhance the signals of low-molecular weight metabolites exclusively, while the signals of lipids, which often are associated with membranes and have relatively lower mobility, were highly sensitive to CP enhancement. PMID:16477685

  2. In Vivo Natural-Abundance 13C Nuclear Magnetic Resonance Studies of Living Ectomycorrhizal Fungi 1

    PubMed Central

    Martin, Francis; Canet, Daniel; Marchal, Jean-Pierre; Brondeau, Jean

    1984-01-01

    Natural-abundance 13C nuclear magnetic resonance spectroscopy has been used to study intact mycelia of the ectomycorrhizal fungi Cenococcum graniforme (Ascomycetes) and Hebeloma crustuliniforme (Basidiomycetes). A number of sharp resonances are observed in living fungi. These signals primarily arise from fatty acyl chains and carbohydrate nuclei. The spectra are interpreted in terms of relative concentrations of the major fatty acids present in the fungal triglycerides. The small line width of fatty acids (mainly oleic, linoleic, and palmitic acids) resonances and spin-lattice relaxation time are indicative of fast rotational reorientations and are consequently thought to arise from fatty acyl chains in fat droplets. We were able to locate the site of lipids accumulation within mycelia using light microscopy and histological staining. Many lipid droplets were observed in mycelia of both species. These results suggest that fatty acids droplets could be involved in carbon storage and metabolism from ectomycorrhizal fungi. PMID:16663561

  3. Evidence of 13C non-covalent isotope effects obtained by quantitative 13C nuclear magnetic resonance spectroscopy at natural abundance during normal phase liquid chromatography.

    PubMed

    Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Rojas, Jose Manuel Moreno; Guillou, Claude; Remaud, Gérald S

    2009-10-16

    Quantitative isotopic (13)C NMR at natural abundance has been used to determine the site-by-site (13)C/(12)C ratios in vanillin and a number of related compounds eluted from silica gel chromatography columns under similar conditions. Head-to-tail isotope fractionation is observed in all compounds at the majority of carbon positions. Furthermore, the site-specific isotope deviations show signatures characteristic of the position and functionality of the substituents present. The observed effects are more complex than would be obtained by simply summing the individual effects. Such detail is hidden when only the global (13)C content is measured by mass spectrometry. In particular, carbon positions within the aromatic ring are found to show site-specific isotope fractionation between the solute and the stationary phase. These interactions, defined as non-covalent isotope effects, can be normal or inverse and vary with the substitution pattern present. PMID:19748628

  4. Position-Specific Isotope Analysis of Xanthines: A (13)C Nuclear Magnetic Resonance Method to Determine the (13)C Intramolecular Composition at Natural Abundance.

    PubMed

    Diomande, Didier G; Martineau, Estelle; Gilbert, Alexis; Nun, Pierrick; Murata, Ariaki; Yamada, Keita; Watanabe, Naoharu; Tea, Illa; Robins, Richard J; Yoshida, Naohiro; Remaud, Gérald S

    2015-07-01

    The natural xanthines caffeine, theobromine, and theophylline are of major commercial importance as flavor constituents in coffee, cocoa, tea, and a number of other beverages. However, their exploitation for authenticity, a requirement in these commodities that have a large origin-based price-range, by the standard method of isotope ratio monitoring by mass spectrometry (irm-MS) is limited. We have now developed a methodology that overcomes this deficit that exploits the power of isotopic quantitative (13)C nuclear magnetic resonance (NMR) spectrometry combined with chemical modification of the xanthines to enable the determination of positional intramolecular (13)C/(12)C ratios (δ(13)Ci) with high precision. However, only caffeine is amenable to analysis: theobromine and theophylline present substantial difficulties due to their poor solubility. However, their N-methylation to caffeine makes spectral acquisition feasible. The method is confirmed as robust, with good repeatability of the δ(13)Ci values in caffeine appropriate for isotope fractionation measurements at natural abundance. It is shown that there is negligible isotope fractionation during the chemical N-methylation procedure. Thus, the method preserves the original positional δ(13)Ci values. The method has been applied to measure the position-specific variation of the (13)C/(12)C distribution in caffeine. Not only is a clear difference between caffeine isolated from different sources observed, but theobromine from cocoa is found to show a (13)C pattern distinct from that of caffeine. PMID:26067163

  5. Characterization of Stratum Corneum Molecular Dynamics by Natural-Abundance 13C Solid-State NMR

    PubMed Central

    Bouwstra, Joke A.; Sparr, Emma; Topgaard, Daniel

    2013-01-01

    Despite the enormous potential for pharmaceutical applications, there is still a lack of understanding of the molecular details that can contribute to increased permeability of the stratum corneum (SC). To investigate the influence of hydration and heating on the SC, we record the natural-abundance 13C signal of SC using polarization transfer solid-state NMR methods. Resonance lines from all major SC components are assigned. Comparison of the signal intensities obtained with the INEPT and CP pulse sequences gives information on the molecular dynamics of SC components. The majority of the lipids are rigid at 32°C, and those lipids co-exist with a small pool of mobile lipids. The ratio between mobile and rigid lipids increases with hydration. An abrupt change of keratin filament dynamics occurs at RH = 80–85%, from completely rigid to a structure with rigid backbone and mobile protruding terminals. Heating has a strong effect on the lipid mobility, but only a weak influence on the keratin filaments. The results provide novel molecular insight into how the SC constituents are affected by hydration and heating, and improve the understanding of enhanced SC permeability, which is associated with elevated temperatures and SC hydration. PMID:23626744

  6. Critical evaluation of 13C natural abundance techniques to partition soil-surface CO2 efflux

    NASA Astrophysics Data System (ADS)

    Snell, H.; Midwood, A. J.; Robinson, D.

    2013-12-01

    Soil is the largest terrestrial store of carbon and the flux of CO2 from soils to the atmosphere is estimated at around 98 Pg (98 billion tonnes) of carbon per year. The CO2 efflux from the soil surface is derived from plant root and rhizosphere respiration (autotrophically fuelled) and microbial degradation of soil organic matter (heterotrophic respiration). Heterotrophic respiration is a key determinant of an ecosystem's long-term C balance, but one that is difficult to measure in the field. One approach involves partitioning the total soil-surface CO2 efflux between heterotrophic and autotrophic components; this can be done using differences in the natural abundance stable isotope ratios (δ13C) of autotrophic and heterotrophic CO2 as the end-members of a simple mixing model. In most natural, temperate ecosystems, current and historical vegetation cover (and therefore also plant-derived soil organic matter) is produced from C3 photosynthesis so the difference in δ13C between the autotrophic and heterotrophic CO2 sources is small. Successful partitioning therefore requires accurate and precise measurements of the δ13CO2 of the autotrophic and heterotrophic end-members (obtained by measuring the δ13CO2 of soil-free roots and root-free soil) and of total soil CO2 efflux. There is currently little consensus on the optimum measurement protocols. Here we systematically tested some of the most commonly used techniques to identify and minimise methodological errors. Using soil-surface chambers to sample total CO2 efflux and a cavity ring-down spectrometer to measure δ13CO2 in a partitioning study on a Scottish moorland, we found that: using soil-penetrating collars leads to a more depleted chamber measurement of total soil δ13CO2 as a result of severing roots and fungal hyphae or equilibrating with δ13CO2 at depth or both; root incubations provide an accurate estimate of in-situ root respired δ13CO2 provided they are sampled within one hour; the δ13CO2 from root

  7. The natural 13C abundance of plasma glucose is a useful biomarker of recent dietary caloric sweetener intake.

    PubMed

    Cook, Chad M; Alvig, Amy L; Liu, Yu Qiu David; Schoeller, Dale A

    2010-02-01

    There is a need for objective biomarkers of dietary intake, because self-reporting is often subject to bias. We tested the validity of a biomarker for the fraction of dietary carbohydrate (CHO) from cane sugar and high fructose corn syrup (C(4) sugars) using natural (13)C abundance of plasma glucose. In a randomized, single-blinded, crossover design, 5 participants consumed 3 weight-maintaining diets for 7 d, with a 2-wk washout between diet periods. Diets differed in the fraction of total CHO energy from C(4) sugars (5, 16, or 32%). During each diet period, blood samples were drawn at hours 0800 and 1600 on d 1, 3, and 5 and at 0800, 1000, 1200, 1400, and 1600 on d 7. The delta(13)C abundance of plasma glucose was analyzed via GC- isotope ratio MS. Within each diet period, delta(13)C abundance of the 0800 fasting glucose did not change from baseline with increasing time during a diet period; however, there was a strong positive correlation (R(2) = 0.89) between delta(13)C abundance of the glucose concentration at 1000 on d 7 and the percent of breakfast CHO from C(4) sugars. Also, delta(13)C abundance of the combined plasma glucose samples on d 7 demonstrated a strong positive correlation (R(2) = 0.90) with the percent of total daily CHO from C(4) sugars. The natural delta(13)C abundance of postprandial plasma glucose relative to dietary C(4) CHO content was a valid biomarker for contributions of C(4) caloric sweeteners from the previous meal. PMID:20018804

  8. Afforestation impacts microbial biomass and its natural (13)C and (15)N abundance in soil aggregates in central China.

    PubMed

    Wu, Junjun; Zhang, Qian; Yang, Fan; Lei, Yao; Zhang, Quanfa; Cheng, Xiaoli

    2016-10-15

    We investigated soil microbial biomass and its natural abundance of δ(13)C and δ(15)N in aggregates (>2000μm, 250-2000μm, 53-250μm and <53μm) of afforested (implementing woodland and shrubland plantations) soils, adjacent croplands and open area (i.e., control) in the Danjiangkou Reservoir area of central China. The afforested soils averaged higher microbial biomass carbon (MBC) and nitrogen (MBN) levels in all aggregates than in open area and cropland, with higher microbial biomass in micro-aggregates (<250μm) than in macro-aggregates (>2000μm). The δ(13)C of soil microbial biomass was more enriched in woodland soils than in other land use types, while δ(15)N of soil microbial biomass was more enriched compared with that of organic soil in all land use types. The δ(13)C and δ(15)N of microbial biomass were positively correlated with the δ(13)C and δ(15)N of organic soil across aggregates and land use types, whereas the (13)C and (15)N enrichment of microbial biomass exhibited linear decreases with the corresponding C:N ratio of organic soil. Our results suggest that shifts in the natural (13)C and (15)N abundance of microbial biomass reflect changes in the stabilization and turnover of soil organic matter (SOM) and thereby imply that afforestation can greatly impact SOM accumulation over the long-term. PMID:27285796

  9. Quantitation of metabolic compartmentation in hyperammonemic brain by natural abundance 13C-NMR detection of 13C-15N coupling patterns and isotopic shifts.

    PubMed

    Lapidot, A; Gopher, A

    1997-02-01

    In the present study, the removal of cerebral ammonia by glutamine synthetase (GS) and by reductive amination of 2-oxoglutarate by glutamate dehydrogenase in the presence of an amino donor group, was determined in hyperammonemic rabbit brains. The 15N enrichments of brain metabolite alpha-amino and amide positions of glutamine, glutamate, and alanine were determined by the indirect detection of 15N-labeled compounds of the 13C-15N spin coupling patterns of natural abundance 13C-NMR spectra. The 13C-NMR spectra of brain extracts were obtained from rabbits infused with 15NH4Cl with or without intraperitoneal infusion of the GS inhibitor, L-methionine DL-sulfoximine, in a reasonable acquisition time period. When 15NH4Cl was infused, [5-15N]glutamine and [2-15N]glutamine concentrations reached 5.2 mumol/100 mg protein and 3.6 mumol/100 mg protein, respectively, which indicates the relatively high activity of reductive amination of 2-oxoglutarate in the glutamate dehydrogenase reaction. The low concentration of [2-15N]glutamate, which is about 30% of that of [2-15N]glutamine obtained in this study, suggests that very little glutamine serves as a precursor of neuronal glutamate. When GS was inhibited by L-methionine DL-sulfoximine, a flux of 15NH4+ via the residual activity of GS was accompanied by an apparent increase of [2-15N]glutamate and [15N]alanine concentrations (2.9 mumol/100 mg protein and 1.8 mumol/100 mg protein, respectively). These findings and those obtained from 13C-13C isotopomer analysis (Lapidot and Gopher, 1994b) suggest that astrocytic 2-oxoglutarate is partially utilized (together with an amino group donor) as a precursor for neuronal glutamate in the hyperammonemic brain when GS is inhibited. This process can partly replace GS activity in metabolizing ammonia in the hyperammonemic rabbit brain. PMID:9057821

  10. Natural abundance measurements of 13C indicate increased deep soil carbon mineralization after forest disturbance

    NASA Astrophysics Data System (ADS)

    Diochon, Amanda; Kellman, Lisa

    2008-07-01

    Northern forest soils represent globally important stores of carbon (C), yet there is no consensus about how they are altered by the widespread practice of harvesting that dominates many forested landscapes. Here we present the first study to systematically investigate the utility of δ 13C and C content depth profiles to infer temporal changes in belowground carbon cycling processes following disturbance in a pure C3 ecosystem. We document carbon concentration and δ 13C depth profile enrichment trends consistent with a kinetic fractionation arising from soil organic carbon (SOC) humification across a northern forest chronosequence (1, 15, 45, 80 and 125+ yrs). Reduced soil C storage that coincided with observed soil profile δ 13C-enrichment patterns which intensified following clearcut harvesting, pointed to losses of SOC in the deeper (>20 cm) mineral soil. This study suggests the δ 13C approach may assist in identifying mechanisms responsible for soil C storage changes in disturbed C3 forest ecosystems.

  11. The natural abundance of 13C with different agricultural management by NIRS with fibre optic probe technology.

    PubMed

    Fuentes, Mariela; González-Martín, Inmaculada; Hernández-Hierro, Jose Miguel; Hidalgo, Claudia; Govaerts, Bram; Etchevers, Jorge; Sayre, Ken D; Dendooven, Luc

    2009-06-30

    In the present study the natural abundance of (13)C is quantified in agricultural soils in Mexico which have been submitted to different agronomic practices, zero and conventional tillage, retention of crop residues (with and without) and rotation of crops (wheat and maize) for 17 years, which have influenced the physical, chemical and biological characteristics of the soil. The natural abundance of C13 is quantified by near infrared spectra (NIRS) with a remote reflectance fibre optic probe, applying the probe directly to the soil samples. Discriminate partial least squares analysis of the near infrared spectra allowed to classify soils with and without residues, regardless of the type of tillage or rotation systems used with a prediction rate of 90% in the internal validation and 94% in the external validation. The NIRS calibration model using a modified partial least squares regression allowed to determine the delta(13)C in soils with or without residues, with multiple correlation coefficients 0.81 and standard error prediction 0.5 per thousand in soils with residues and 0.92 and 0.2 per thousand in soils without residues. The ratio performance deviation for the quantification of delta(13)C in soil was 2.5 in soil with residues and 3.8 without residues. This indicated that the model was adequate to determine the delta(13)C of unknown soils in the -16.2 per thousand to -20.4 per thousand range. The development of the NIR calibration permits analytic determinations of the values of delta(13)C in unknown agricultural soils in less time, employing a non-destructive method, by the application of the fibre optic probe of remote reflectance to the soil sample. PMID:19376340

  12. Food webs in Mongolian grasslands: the analysis of 13C and 15N natural abundances.

    PubMed

    Kohzu, Ayato; Iwata, T; Kato, M; Nishikawa, J; Wada, Eitaro; Amartuvshin, N; Namkhaidorj, B; Fujita, N

    2009-09-01

    Overgrazing often lowers species richness and productivity of grassland communities. For Mongolian grassland ecosystems, a lack of detailed information about food-web structures makes it difficult to predict the effects of overgrazing on species diversity and community composition. We analysed the delta13C and delta15N signatures of herbaceous plants, arthropods (grouped by feeding habit), wild and domestic mammals, and humans in central Mongolia to understand the predominant food-web pathways in this grassland ecosystem. The delta13C and delta15N values of mammals showed little variation within species, but varied considerably with slope position for arthropods. The apparent isotopic discrimination between body tissue and hair of mammals was estimated as 2.0 per thousand for delta13C and 2.1 per thousand for delta15N, which was large enough to cause overestimation of the trophic level of mammals if not taken into account when using hair samples to measure isotopic enrichment. PMID:19507080

  13. Natural abundance and 13C-enriched characterisation of atmospheric methane uptake in a forest soil

    NASA Astrophysics Data System (ADS)

    Maxfield, Peter; Hornibrook, Edward; Evershed, Richard

    2013-04-01

    Whilst much attention is focused on CH4 emission inventories, CH4 sinks are sometimes overlooked and not accurately accounted for in national budgets. Two primary reasons for this disjunction include uncertainties about the magnitude and mechanism of terrestrial CH4 oxidation, and an under-appreciation of the quantity of CH4 that is removed from the atmosphere by microorganisms. These uncertainties in part are caused by a lack of high-resolution field data that quantify microbial soil CH4 sink. To fully characterize the soil CH4 sink, isotopic fractionation of CH4during uptake and the fate of CH4 carbon following oxidation by soil microorganisms should be quantified in addition to CH4 fluxes. Here we report on field tests studying CH4 uptake in soil using a Picarro G2201-i cavity ringdown spectrometer (CRDS). Short term atmospheric CH4 uptake was continuously measured in a forest soil in Leigh Woods, UK where the soil methanotrophic community and soil CH4 uptake kinetic isotopic effect (KIE) had been previously quantified using stable isotope probing and conventional stable isotope analysis techniques (Maxfield et al., 2008). Two methodological approaches were tested: (i) direct measurement of the soil CH4 uptake KIE at subambient CH4 concentrations, and (ii) methanotrophic carbon conversion efficiency (CCE) where CCE was evaluated through monitoring the direct conversion of 13C-labelled CH4 to 13C-labelled CO2. The suitability of the G2201-i analyzer as a continuous isotopic CH4 and CO2 analyzer for use at both subambient CH4 concentrations and high 13C-enrichments will be discussed. Maxfield, P.J., Evershed, R.P. and Hornibrook, E.R.C. (2008) Physical and biological controls on the in situ kinetic isotope effect associated with oxidation of atmospheric CH4 in mineral soils. Environmental Science & Technology, 42, 7824-7830.

  14. 13C natural abundance in serum retinol acts as a biomarker for increases in dietary provitamin A.

    PubMed

    Howe, Julie A; Valentine, Ashley R; Hull, Angela K; Tanumihardjo, Sherry A

    2009-02-01

    The natural isotopic composition of 13C and 12C in tissues is largely determined by the diet. Sources of provitamin A carotenoids (e.g., vegetables) typically have a lower 13C to 12C ratio (13C:12C) than preformed vitamin A sources (i.e., dairy and meat) from corn-fed animals, which are prevalent in the US. The 13C:12C of serum retinol (13C:12C-retinol) was evaluated as a biomarker for vegetable intake in a 3-mo dietary intervention designed to promote weight-loss by increased vegetable consumption or reduced calorie and fat intake. Subjects were 21-50 y of age with a BMI between 30-40 kg/m2 and were enrolled from one geographic area in the US. The high vegetable group (n=20) was encouraged to increase daily vegetable and fruit consumption to 0.95 liter vegetables and 0.24-0.35 liter fruits. The caloric reduction group (n=17) was encouraged to lower caloric intake by 500 kcal and consume13C:12C-retinol. 13C:12C-Retinol decreased in the vegetable group after intervention (P=0.050) and the correlation with provitamin A intake was approaching significance (P=0.079). 13C:12C-Retinol did not change in the caloric reduction group (P=0.43). 13C:12C-Retinol changes with the vitamin A source in the diet and can be used as a biomarker for increases in dietary provitamin A vegetable intake. PMID:19116317

  15. Plant diversity moderates drought stress in grasslands: Implications from a large real-world study on (13)C natural abundances.

    PubMed

    Klaus, Valentin H; Hölzel, Norbert; Prati, Daniel; Schmitt, Barbara; Schöning, Ingo; Schrumpf, Marion; Solly, Emily F; Hänsel, Falk; Fischer, Markus; Kleinebecker, Till

    2016-10-01

    Land-use change and intensification play a key role in the current biodiversity crisis. The resulting species loss can have severe effects on ecosystem functions and services, thereby increasing ecosystem vulnerability to climate change. We explored whether land-use intensification (i.e. fertilization intensity), plant diversity and other potentially confounding environmental factors may be significantly related to water use (i.e. drought stress) of grassland plants. Drought stress was assessed using δ(13)C abundances in aboveground plant biomass of 150 grassland plots across a gradient of land-use intensity. Under water shortage, plants are forced to increasingly take up the heavier (13)C due to closing stomata leading to an enrichment of (13)C in biomass. Plants were sampled at the community level and for single species, which belong to three different functional groups (one grass, one herb, two legumes). Results show that plant diversity was significantly related to the δ(13)C signal in community, grass and legume biomass indicating that drought stress was lower under higher diversity, although this relation was not significant for the herb species under study. Fertilization, in turn, mostly increased drought stress as indicated by more positive δ(13)C values. This effect was mostly indirect by decreasing plant diversity. In line with these results, we found similar patterns in the δ(13)C signal of the organic matter in the topsoil, indicating a long history of these processes. Our study provided strong indication for a positive biodiversity-ecosystem functioning relationship with reduced drought stress at higher plant diversity. However, it also underlined a negative reinforcing situation: as land-use intensification decreases plant diversity in grasslands, this might subsequently increases drought sensitivity. Vice-versa, enhancing plant diversity in species-poor agricultural grasslands may moderate negative effects of future climate change. PMID:27220098

  16. 13C Natural Abundance in Serum Retinol Acts as a Biomarker for Increases in Dietary Provitamin A

    PubMed Central

    Howe, Julie A; Valentine, Ashley R; Hull, Angela K; Tanumihardjo, Sherry A

    2009-01-01

    The natural isotopic composition of 13C and 12C in tissues is largely determined by the diet. Sources of provitamin A carotenoids (e.g., vegetables) typically have a lower 13C to 12C ratio (13C:12C) than preformed vitamin A sources (i.e., dairy and meat) from corn-fed animals, which are prevalent in the US. The 13C:12C of serum retinol (13C:12C-retinol) was evaluated as a biomarker for vegetable intake in a 3-mo dietary intervention designed to promote weight-loss by increased vegetable consumption or reduced calorie and fat intake. Subjects were 21–50 y of age with a BMI between 30–40 kg/m2 and were enrolled from one geographic area in the US. The high vegetable group (n = 20) was encouraged to increase daily vegetable and fruit consumption to 0.95 liter vegetables and 0.24–0.35 liter fruits. The caloric reduction group (n = 17) was encouraged to lower caloric intake by 500 kcal and consume ≤25% kcal from fat daily. Provided meals supplied 75–100% vegetable and fruit goals and 50–67% kcal and fat g per day. Carotenoid supplementation was discontinued by subjects during the study. Serum retinol and provitamin A carotenoid concentrations; intake of preformed vitamin A, provitamin A, and fat; and body weight, fat mass, and lean mass were analyzed for correlations to 13C:12C-retinol. 13C:12C-Retinol decreased in the vegetable group after intervention (P = 0.050) and the correlation with provitamin A intake was approaching significance (P = 0.079). 13C:12C-Retinol did not change in the caloric reduction group (P = 0.43). 13C:12C-Retinol changes with the vitamin A source in the diet and can be used as a biomarker for increases in dietary provitamin A vegetable intake. PMID:19116317

  17. Effect of petroleum products on the decomposition of soil organic matter as assessed by 13C natural abundance

    NASA Astrophysics Data System (ADS)

    Stelmach, Wioleta; Szarlip, Paweł; Trembaczowski, Andrzej; Bieganowski, Andrzej

    2016-04-01

    Petroleum products are common contaminants in soils due to human activities. They are toxic for microorganisms and threat their functions, including decomposition of soil organic matter (SOM). The direct estimation of altered SOM decomposition - based on the CO2 emission - is impossible after oil contamination, because oil decomposition also contributes to the CO2 release. We used the natural differences in the isotopic signature (δ13C) of SOM and of oil products to partition the total CO2 for both sources and to analyze the suppression of SOM decomposition. The dynamics of 13C fractionation during the mineralization of gasoline and diesel was measured during 42 days. The 13C fractionation varied between -8.8‰ and +3.6‰ within the first 10 days, and stabilized thereafter at about -5.3‰ for gasoline and +3.2‰ for diesel. These 13C fractionations and δ13C values of CO2 emitted from the soil were used for correct partitioning of the total CO2. Contamination with gasoline reduced the CO2 efflux from SOM decomposition by a factor of 25 (from 151 to 6 mg C-CO2 kg‑1 soil during 42 days). The negative effect of diesel was much lower: the CO2 efflux from SOM was decreased by less than a factor of 2. The strong effect of gasoline versus diesel reflects the lower absorption of gasoline to mineral particles and the development of a thin film on water surfaces, leading to toxicity for microorganisms. We conclude that the small differences of 13C of SOM and of organic pollutants can be used to partition CO2 fluxes and analyze pollutant effects on SOM decomposition.

  18. Land use Effects on Storage, Stability and Structure of Organic Carbon in Soil Density Fractions Revealed by 13C Natural Abundance and CPMAS 13C NMR

    NASA Astrophysics Data System (ADS)

    Flessa, H.; Helfrich, M.; John, B.; Yamashita, T.; Ludwig, B.

    2004-12-01

    The type of land use and soil cultivation are important factors controlling organic carbon storage (SOC) in soils and they can also influence the relative importance, the structure, and the stability of different SOC pools. The objectives of our study were: i) to quantify the SOC stocks in different density fractions (mineral-associated soil organic matter > 2 g cm-3 (Mineral-SOM), free particulate organic matter < 1.6 g cm-3 (free POM), light occluded particulate organic matter < 1.6 g cm-3 (occluded POM<1.6) and dense occluded particulate organic matter 1.6 to 2.0 g cm-3 (occluded POM1.6-2.0)) of silty soils under different land use (spruce forest, grassland, maize, wheat), ii) to determine the structure of these SOC fractions by CPMAS 13C NMR spectroscopy, and iii) to analyse the stability of these SOC fractions in the maize soil on the basis of the stable isotope composition of SOC. The SOC concentration in the A horizon increased in the order wheat (12.7 g kg-1) < maize (13.0 g kg-1) < grassland (24.5 g kg-1) < spruce (40.5 g kg-1). The major part (86-91%) of the SOC was associated with the heavy mineral fraction at the grassland, maize and wheat site. In the A horizon of the spruce soil, the particulate organic matter accounted for 52% of the total SOC content. The chemical structure of the soil organic matter (SOM) was influenced by litter quality, the intensity of litter decomposition and the related production and storage of microbially-derived substances. SOM of the acid forest soil was characterized by large amounts of POM with a high content of spruce litter-derived alkyl C. In the biologically more active grassland and maize soil, litter-derived POM was decomposed more rapidly and SOC stocks were dominated by mineral-associated SOM which contained greater proportions of aryl and carbonyl C. The cultivation of the grassland soil induced enhanced mineralization of POM and in particular of mineral-associated SOM. The faster SOC turnover was associated

  19. A New Tool for NMR Crystallography: Complete (13)C/(15)N Assignment of Organic Molecules at Natural Isotopic Abundance Using DNP-Enhanced Solid-State NMR.

    PubMed

    Märker, Katharina; Pingret, Morgane; Mouesca, Jean-Marie; Gasparutto, Didier; Hediger, Sabine; De Paëpe, Gaël

    2015-11-01

    NMR crystallography of organic molecules at natural isotopic abundance (NA) strongly relies on the comparison of assigned experimental and computed NMR chemical shifts. However, a broad applicability of this approach is often hampered by the still limited (1)H resolution and/or difficulties in assigning (13)C and (15)N resonances without the use of structure-based chemical shift calculations. As shown here, such difficulties can be overcome by (13)C-(13)C and for the first time (15)N-(13)C correlation experiments, recorded with the help of dynamic nuclear polarization. We present the complete de novo (13)C and (15)N resonance assignment at NA of a self-assembled 2'-deoxyguanosine derivative presenting two different molecules in the asymmetric crystallographic unit cell. This de novo assignment method is exclusively based on aforementioned correlation spectra and is an important addition to the NMR crystallography approach, rendering firstly (1)H assignment straightforward, and being secondly a prerequisite for distance measurements with solid-state NMR. PMID:26485326

  20. Natural 15N- and 13C-abundance as indicators of forest nitrogen status and soil carbon dynamics

    SciTech Connect

    Garten Jr, Charles T; Hanson, Paul J; Todd Jr, Donald E; Lu, Benwhea Bonnie; Brice, Deanne Jane

    2007-09-01

    This book highlights new and emerging uses of stable isotope analysis in a variety of ecological disciplines. While the use of natural abundance isotopes in ecological research is now relatively standard, new techniques and ways of interpreting patterns are developing rapidly. The second edition of this book provides a thorough, up-to-date examination of these methods of research. As part of the Ecological Methods and Concepts series which provides the latest information on experimental techniques in ecology, this book looks at a wide range of techniques that use natural abundance isotopes to: {sm_bullet} follow whole ecosystem element cycling {sm_bullet} understand processes of soil organic matter formation {sm_bullet} follow the movement of water in whole watersheds {sm_bullet} understand the effects of pollution in both terrestrial and aquatic environments {sm_bullet} study extreme systems such as hydrothermal vents {sm_bullet}follow migrating organisms In each case, the book explains the background to the methodology, looks at the underlying principles and assumptions, and outlines the potential limitations and pitfalls. Stable Isotopes in Ecology and Environmental Science is an ideal resource for both ecologists who are new to isotopic analysis, and more experienced isotope ecologists interested in innovative techniques and pioneering new uses.

  1. Molecular Investigation of the Short-term Sequestration of Natural Abundance 13C -labelled Cow Dung in the Surface Horizons of a Temperate Grassland Soil

    NASA Astrophysics Data System (ADS)

    Dungait, J.; Bol, R.; Evershed, R. P.

    2004-12-01

    An adequate understanding of the carbon (C) sequestration potential of grasslands requires that the quantity and residence times of C inputs be measured. Herbivore dung is largely comprised of plant cell wall material, a significant source of stable C in intensively grazed temperate grassland ecosystems that contributes to the soil carbon budget. Our work uses compound-specific isotope analysis to identify the pattern of input of dung-derived compounds from natural abundance 13C/-labelled cow dung into the surface horizons of a temperate grassland soil over one year. C4 dung (δ 13C \\-12.6 ‰ ) from maize fed cows was applied to a temperate grassland surface (δ 13C \\-29.95 ‰ ) at IGER-North Wyke (Devon, UK), and dung remains and soil cores beneath the treatments collected at ŧ = 7, 14, 28, 56, 112, 224 and 372 days. Bulk dung carbon present in the 0\\-1 cm and 1\\-5 cm surface horizons of a grassland soil over one year was estimated using Δ 13C between C4 dung and C3 dung, after Bol {\\et al.} (2000). The major biochemical components of dung were quantified using proximate forage fibre analyses, after Goering and Van Soest (1970) and identified using `wet' chemical and GC-MS methods. Plant cell wall polysaccharides and lignin were found to account for up to 67 {%} of dung dry matter. Hydrolysed polysaccharides were prepared as alditol acetates for analyses (after Docherty {\\et al.}, 2001), and a novel application of an off-line pyrolysis method applied to measure lignin-derived phenolic compounds (after Poole & van Bergen, 2002). This paper focuses on major events in the incorporation of dung carbon, estimated using natural abundance 13C&-slash;labelling technique. This revealed a major bulk input of dung carbon after a period of significant rainfall with a consequent decline in bulk soil δ 13C values until the end of the experiment (Dungait {\\et al.}, submitted). Findings will be presented revealing contribution of plant cell wall polysaccharides and

  2. Early-stage changes in natural (13)C and (15)N abundance and nutrient dynamics during different litter decomposition.

    PubMed

    Gautam, Mukesh Kumar; Lee, Kwang-Sik; Song, Byeong-Yeol; Lee, Dongho; Bong, Yeon-Sik

    2016-05-01

    Decomposition, nutrient, and isotopic (δ(13)C and δ(15)N) dynamics during 1 year were studied for leaf and twig litters of Pinus densiflora, Castanea crenata, Erigeron annuus, and Miscanthus sinensis growing on a highly weathered soil with constrained nutrient supply using litterbags in a cool temperate region of South Korea. Decay constant (k/year) ranged from 0.58 to 1.29/year, and mass loss ranged from 22.36 to 58.43 % among litter types. The results demonstrate that mass loss and nutrient dynamics of decomposing litter were influenced by the seasonality of mineralization and immobilization processes. In general, most nutrients exhibited alternate phases of rapid mineralization followed by gradual immobilization, except K, which was released throughout the field incubation. At the end of study, among all the nutrients only N and P showed net immobilization. Mobility of different nutrients from decomposing litter as the percentage of initial litter nutrient concentration was in the order of K > Mg > Ca > N ≈ P. The δ(13)C (0.32-6.70 ‰) and δ(15)N (0.74-3.90 ‰) values of residual litters showed nonlinear increase and decrease, respectively compared to initial isotopic values during decomposition. Litter of different functional types and chemical quality converged toward a conservative nutrient use strategy through mechanisms of slow decomposition and slow nutrient mobilization. Our results indicate that litter quality and season, are the most important regulators of litter decomposition in these forests. The results revealed significant relationships between litter decomposition rates and N, C:N ratio and P, and seasonality (temperature). These results and the convergence of different litters towards conservative nutrient use in these nutrient constrained ecosystems imply optimization of litter management because litter removal can have cascading effects on litter decomposition and nutrient availability in these systems. PMID:26915037

  3. High-precision optical measurements of 13C/12C isotope ratios in organic compounds at natural abundance

    PubMed Central

    Zare, Richard N.; Kuramoto, Douglas S.; Haase, Christa; Tan, Sze M.; Crosson, Eric R.; Saad, Nabil M. R.

    2009-01-01

    A continuous-flow cavity ring-down spectroscopy (CRDS) system integrating a chromatographic separation technique, a catalytic combustor, and an isotopic 13C/12C optical analyzer is described for the isotopic analysis of a mixture of organic compounds. A demonstration of its potential is made for the geochemically important class of short-chain hydrocarbons. The system proved to be linear over a 3-fold injection volume dynamic range with an average precision of 0.95‰ and 0.67‰ for ethane and propane, respectively. The calibrated accuracy for methane, ethane, and propane is within 3‰ of the values determined using isotope ratio mass spectrometry (IRMS), which is the current method of choice for compound-specific isotope analysis. With anticipated improvements, the low-cost, portable, and easy-to-use CRDS-based instrumental setup is poised to evolve into a credible challenge to the high-cost and complex IRMS-based technique. PMID:19564619

  4. Natural abundances of 15N and 13C in leaves of some N2-fixing and non-N2-fixing trees and shrubs in Syria.

    PubMed

    Kurdali, F; Al-Shamma'a, M

    2009-09-01

    A survey study was conducted on man-made plantations located at two different areas in the arid region of Syria to determine the variations in natural abundances of the (15)N and (13)C isotopes in leaves of several woody legume and non-legume species, and to better understand the consequence of such variations on nitrogen fixation and carbon assimilation. In the first study area (non-saline soil), the delta(15)N values in four legume species (Acacia cyanophylla,-1.73 per thousand Acacia farnesiana,-0.55 per thousand Prosopis juliflora,-1.64 per thousand; and Medicago arborea,+1.6 \\textperthousand) and one actinorhizal plant (Elaeagnus angustifolia,-0.46 to-2.1 per thousand) were found to be close to that of the atmospheric value pointing to a major contribution of N(2) fixing in these species; whereas, delta(15)N values of the non-fixing plant species were highly positive. delta(13)C per thousand; in leaves of the C3 plants were found to be affected by plant species, ranging from a minimum of-28.67 per thousand; to a maximum of-23 per thousand. However, they were relatively similar within each plant species although they were grown at different sites. In the second study area (salt affected soil), a higher carbon discrimination value (Delta(13)C per thousand) was exhibited by P. juliflora, indicating that the latter is a salt tolerant species; however, its delta(15)N was highly positive (+7.03 per thousand) suggesting a negligible contribution of the fixed N(2). Hence, it was concluded that the enhancement of N(2) fixation might be achieved by selection of salt-tolerant Rhizobium strains. PMID:20183233

  5. NMR profiling of biomolecules at natural abundance using 2D 1H-15N and 1H-13C multiplicity-separated (MS) HSQC spectra

    NASA Astrophysics Data System (ADS)

    Chen, Kang; Freedberg, Darón I.; Keire, David A.

    2015-02-01

    2D NMR 1H-X (X = 15N or 13C) HSQC spectra contain cross-peaks for all XHn moieties. Multiplicity-edited1H-13C HSQC pulse sequences generate opposite signs between peaks of CH2 and CH/CH3 at a cost of lower signal-to-noise due to the 13C T2 relaxation during an additional 1/1JCH period. Such CHn-editing experiments are useful in assignment of chemical shifts and have been successfully applied to small molecules and small proteins (e.g. ubiquitin) dissolved in deuterated solvents where, generally, peak overlap is minimal. By contrast, for larger biomolecules, peak overlap in 2D HSQC spectra is unavoidable and peaks with opposite phases cancel each other out in the edited spectra. However, there is an increasing need for using NMR to profile biomolecules at natural abundance dissolved in water (e.g., protein therapeutics) where NMR experiments beyond 2D are impractical. Therefore, the existing 2D multiplicity-edited HSQC methods must be improved to acquire data on nuclei other than 13C (i.e.15N), to resolve more peaks, to reduce T2 losses and to accommodate water suppression approaches. To meet these needs, a multiplicity-separated1H-X HSQC (MS-HSQC) experiment was developed and tested on 500 and 700 MHz NMR spectrometers equipped with room temperature probes using RNase A (14 kDa) and retroviral capsid (26 kDa) proteins dissolved in 95% H2O/5% D2O. In this pulse sequence, the 1/1JXH editing-period is incorporated into the semi-constant time (semi-CT) X resonance chemical shift evolution period, which increases sensitivity, and importantly, the sum and the difference of the interleaved 1JXH-active and the 1JXH-inactive HSQC experiments yield two separate spectra for XH2 and XH/XH3. Furthermore we demonstrate improved water suppression using triple xyz-gradients instead of the more widely used z-gradient only water-suppression approach.

  6. Conformational study of C8 diazocine turn mimics using {sup 3}J{sub CH} coupling constants with {sup 13}C in natural abundance

    SciTech Connect

    Bean, J.W.; Briand, J.; Burgess, J.L.; Callahan, J.F.

    1994-12-01

    The conformations of two diazocine turn mimics, which were later incorporated into GPIIb/IIIa peptide antagonists, were investigated using nuclear magnetic resonance techniques. The two compounds, methyl (2,5-dioxo-3-(S)-(3-{omega}-tosylguanidino-propyl)-4-methyl-octahydro-1,4-dazocin-1-yl)acetate (1) and methyl (2,5-dioxo-3-(S)-(3-{omega}-tosyl-guanidino-propyl)-octahydro-1,5-diazocin-1-yl)acetate (2), differ only in their substituent at the diazocine position 4 nitrogen, yet this substitution results in a marked difference in the affinity of the resulting analogs for the GPIIb/IIIa receptor. It was of interest to determine if the difference observed in the antagonistic potency between these analogs was related to constitutional or, perhaps, conformational differences. The backbone conformations of these two molecules can be determined by measuring vicinal coupling constants along the trimethylene portion of the C8 ring backbone and by measuring interproton NOE intensities between the diazocine methine proton and the protons of the trimethylene group. For compound 1, {sup 3}J{sub HH} values measured from a P.E.COSY spectrum and interproton distances calculated from ROESY buildup curves indicated the presence of a single C8 ring backbone conformation where the trimethylene bridge adopted a staggered conformation and the H{alpha}1 and H{gamma}1 protons of the trimethylene group were 2.2 A from the methine proton. For compound 2, however, partial overlap of the central H{beta}1 and H{beta}2 protons made it impossible to measure {sup 3}J{sub HH} values from the P.E.COSY spectrum. We therefore used a {sup 13}C-filtered TOCSY experiment to measure the {sup 3}J{sub CH} values in both compounds 1 and 2. These heteronuclear vicinal coupling constants measured with {sup 13}C in natural abundance in conjunction with measured interproton NOE intensities indicate that these compounds share a common C8 ring backbone conformation.

  7. Abundance anomaly of the 13C species of CCH

    NASA Astrophysics Data System (ADS)

    Sakai, N.; Saruwatari, O.; Sakai, T.; Takano, S.; Yamamoto, S.

    2010-03-01

    Aims: We have observed the N = 1-0 lines of CCH and its 13C isotopic species toward a cold dark cloud, TMC-1 and a star-forming region, L1527, to investigate the 13C abundances and formation pathways of CCH. Methods: The observations have been carried out with the IRAM 30 m telescope. Results: We have successfully detected the lines of 13CCH and C13CH toward the both sources and found a significant intensity difference between the two 13C isotopic species. The [C13CH] /[13CCH] abundance ratios are 1.6 ± 0.4 (3σ) and 1.6 ± 0.1 (3σ) for TMC-1 and L1527, respectively. The abundance difference between C13CH and 13CCH means that the two carbon atoms of CCH are not equivalent in the formation pathway. On the other hand, the [CCH]/[C13CH] and [CCH]/[13CCH] ratios are evaluated to be larger than 170 and 250 toward TMC-1, and to be larger than 80 and 135 toward L1527, respectively. Therefore, both of the 13C species are significantly diluted in comparison with the interstellar 12C/13C ratio of 60. The dilution is discussed in terms of a behavior of 13C in molecular clouds.

  8. 13C Natural Abundance of Serum Retinol Is a Novel Biomarker for Evaluating Provitamin A Carotenoid-Biofortified Maize Consumption in Male Mongolian Gerbils123

    PubMed Central

    Pungarcher, India; Mourao, Luciana; Davis, Christopher R; Simon, Philipp; Pixley, Kevin V; Tanumihardjo, Sherry A

    2016-01-01

    Background: Crops such as maize, sorghum, and millet are being biofortified with provitamin A carotenoids to ensure adequate vitamin A (VA) intakes. VA assessment can be challenging because serum retinol concentrations are homeostatically controlled and more sensitive techniques are resource-intensive. Objectives: We investigated changes in serum retinol relative differences of isotope amount ratios of 13C/12C (δ13C) caused by natural 13C fractionation in C3 compared with C4 plants as a biomarker to detect provitamin A efficacy from biofortified (orange) maize and high-carotene carrots. Methods: The design was a 2 × 2 × 2 maize (orange compared with white) by carrot (orange compared with white) by a VA fortificant (VA+ compared with VA−) in weanling male Mongolian gerbils (n = 55), which included a 14-d VA depletion period and a 62-d treatment period (1 baseline and 8 treatment groups; n = 5−7/group). Liver VA and serum retinol were quantified, purified by HPLC, and analyzed by GC combustion isotope ratio mass spectrometry for 13C. Results: Treatments affected liver VA concentrations (0.048 ± 0.039 to 0.79 ± 0.24 μmol/g; P < 0.0001) but not overall serum retinol concentrations (1.38 ± 0.22 μmol/L). Serum retinol and liver VA δ13C were significantly correlated (R2 = 0.92; P < 0.0001). Serum retinol δ13C differentiated control groups that consumed white maize and white carrots (−27.1 ± 1.2 δ13C‰) from treated groups that consumed orange maize and white carrots (−21.6 ± 1.4 δ13C‰ P < 0.0001) and white maize and orange carrots (−30.6 ± 0.7 δ13C‰ P < 0.0001). A prediction model demonstrated the relative contribution of orange maize to total dietary VA for groups that consumed VA from mixed sources. Conclusions: Provitamin A efficacy and quantitative estimation of the relative contribution to dietary VA were demonstrated with the use of serum retinol δ13C. This method could be used for maize efficacy or effectiveness studies and with

  9. Natural 13C abundance reveals trophic status of fungi and host-origin of carbon in mycorrhizal fungi in mixed forests

    PubMed Central

    Högberg, Peter; Plamboeck, Agneta H.; Taylor, Andrew F. S.; Fransson, Petra M. A.

    1999-01-01

    Fungi play crucial roles in the biogeochemistry of terrestrial ecosystems, most notably as saprophytes decomposing organic matter and as mycorrhizal fungi enhancing plant nutrient uptake. However, a recurrent problem in fungal ecology is to establish the trophic status of species in the field. Our interpretations and conclusions are too often based on extrapolations from laboratory microcosm experiments or on anecdotal field evidence. Here, we used natural variations in stable carbon isotope ratios (δ13C) as an approach to distinguish between fungal decomposers and symbiotic mycorrhizal fungal species in the rich sporocarp flora (our sample contains 135 species) of temperate forests. We also demonstrated that host-specific mycorrhizal fungi that receive C from overstorey or understorey tree species differ in their δ13C. The many promiscuous mycorrhizal fungi, associated with and connecting several tree hosts, were calculated to receive 57–100% of their C from overstorey trees. Thus, overstorey trees also support, partly or wholly, the nutrient-absorbing mycelia of their alleged competitors, the understorey trees. PMID:10411910

  10. Distributions and Transformations of Natural Abundance 14C and 13C in Dissolved and Particulate Lipids in a Major Temperate Estuary

    NASA Astrophysics Data System (ADS)

    Bauer, J. E.; Canuel, E. A.; McIntosh, H.; Barrett, A.; Ferer, E.; Hossler, K.

    2013-12-01

    Limited previous studies have shown major differences in the natural 14C and 13C isotopic signatures and radiocarbon ages of different biochemical classes (e.g., proteins, carbohydrates, lipid, etc.) in river, estuarine and marine dissolved and particulate organic matter (DOM and POM, respectively). Of particular note are the much greater radiocarbon ages of lipophilic materials than other compound classes. Possible explanations for these findings include greater-than-expected inputs of fossil and highly aged lipid-containing organic matter to rivers and estuaries, extended sorptive-protection of lipophilic materials from degradation and/or lower overall reactivities of lipids vs. other major biochemical classes. We measured the Delta 14C and del 13C signatures and 14C ages of lipid classes in DOM and POM in a major temperate estuary, Delaware Bay (USA) over two years. Changes in DOM were also followed during large volume dark and light incubations to assess the microbial and photochemical reactivity and processing of DOM and lipids. Neutral lipids in DOM were among the most highly aged (> 30,000 yrs BP) of any materials measured in natural waters to date, and were significantly older than co-occurring polar lipids (~4,000-5,000 yrs BP). In general, DOM lipid ages were significantly greater than POM lipid ages across the river-estuary transect, arguing against sorptive protection as the major factor explaining greater ages of lipid than those of other compound classes. Both dark and light incubations of DOM resulted in losses of very highly aged material (30-50,000 y BP), with the remnant exported lipids being correspondingly younger. The microbial and photochemical alterations were most pronounced for lipids from freshwater reaches of the system (i.e., the Delaware River). These findings suggest that a) dissolved vs. particulate lipids have fundamentally different sources and/or physico-chemical partitioning, b) different lipid classes (e.g., neutral vs. polar

  11. Assessing the use of delta(13)C natural abundance in separation of root and microbial respiration in a Danish beech (Fagus sylvatica L.) forest.

    PubMed

    Formánek, Pavel; Ambus, Per

    2004-01-01

    Our understanding of forest biosphere-atmosphere interactions is fundamental for predicting forest ecosystem responses to climatic changes. Currently, however, our knowledge is incomplete partly due to inability to separate the major components of soil CO(2) effluxes, viz. root respiration, microbial decomposition of soil organic matter and microbial decomposition of litter material. In this study we examined whether the delta(13)C characteristics of solid organic matter and respired CO(2) from different soil-C components and root respiration in a Danish beech forest were useful to provide information on the root respiration contribution to total CO(2) effluxes. The delta(13)C isotopic analyses of CO(2) were performed using a FinniganMAT Delta(PLUS) isotope-ratio mass spectrometer coupled in continuous flow mode to a trace gas preparation-concentration unit (PreCon). Gas samples in 2-mL crimp seal vials were analysed in a fully automatic mode with an experimental standard error +/-0.11 per thousand. We observed that the CO(2) derived from root-free mineral soil horizons (A, B(W)) was more enriched in (13)C (delta(13)C range -21.6 to -21.2 per thousand ) compared with CO(2) derived from root-free humus layers (delta(13)C range -23.6 to -23.4 per thousand ). The CO(2) evolved from root respiration in isolated young beech plants revealed a value intermediate between those for the soil humus and mineral horizons, delta(13)C(root) = -22.2 per thousand, but was associated with great variability (SE +/- 1.0 per thousand ) due to plant-specific differences. delta(13)C of CO(2) from in situ below-ground respiration averaged -22.8 per thousand, intermediate between the values for the humus layer and root respiration, but variability was great (SE +/- 0.4 per thousand ) due to pronounced spatial patterns. Overall, we were unable to statistically separate the CO(2) of root respiration vs. soil organic matter decomposition based solely on delta(13)C signatures, yet the trend in

  12. Incremental vacuum dehydration-decarbonation experiments on a natural gibbsite (α-Al(OH 3)): CO 2 abundance and δ 13C values

    NASA Astrophysics Data System (ADS)

    Tabor, Neil J.; Yapp, Crayton J.

    2005-02-01

    Incremental vacuum dehydration-decarbonation experiments were performed at 190°C on chemically "cleaned" aliquots of a gibbsite-dominated, Eocene-age bauxite sample with evolution of CO 2 and H 2O. "Plateau" F (CO 2/H 2O ratios) and δ 13C values of the CO 2 derived from gibbsite were attained over the dehydration interval, X v(H 2) = 0.16 to 0.67 (i.e., 16 to 67% breakdown of gibbsite). The plateau value of F for gibbsite was 0.0043 ± 0.0003, while the corresponding δ 13C value of evolved CO 2 was -16.0‰±0.4‰. Additional experiments on chemically cleaned aliquots included (1) treatment with a solution of 0.3M Na-Citrate + 0.1M Na-Dithionite and (2) an exchange experiment with 0.1 bar of 13C-depleted CO 2 (-46‰) at 105°C for 64.5 h. Neither of these additional treatments resulted in a measurable perturbation of plateau values of F or δ 13C for CO 2 evolved from gibbsite during dehydroxylation. These results support published work on Holocene samples which suggested that CO 2 occluded in gibbsite may preserve information on δ 13C values of CO 2 in ancient terrestrial systems. The plateau values of F observed in the Eocene gibbsite indicate that it may be possible to experimentally calibrate a relationship between the concentration of CO 2 occluded in gibbsite and CO 2 in the environment at the time of crystallization. Such a calibration would significantly enhance the value of gibbsite as a source of information on ancient oxidized carbon systems.

  13. Priming of Soil Carbon Decomposition in Two Inner Mongolia Grassland Soils following Sheep Dung Addition: A Study Using 13C Natural Abundance Approach

    PubMed Central

    Ma, Xiuzhi; Ambus, Per; Wang, Shiping; Wang, Yanfen; Wang, Chengjie

    2013-01-01

    To investigate the effect of sheep dung on soil carbon (C) sequestration, a 152 days incubation experiment was conducted with soils from two different Inner Mongolian grasslands, i.e. a Leymus chinensis dominated grassland representing the climax community (2.1% organic matter content) and a heavily degraded Artemisia frigida dominated community (1.3% organic matter content). Dung was collected from sheep either fed on L. chinensis (C3 plant with δ13C = −26.8‰; dung δ13C = −26.2‰) or Cleistogenes squarrosa (C4 plant with δ13C = −14.6‰; dung δ13C = −15.7‰). Fresh C3 and C4 sheep dung was mixed with the two grassland soils and incubated under controlled conditions for analysis of 13C-CO2 emissions. Soil samples were taken at days 17, 43, 86, 127 and 152 after sheep dung addition to detect the δ13C signal in soil and dung components. Analysis revealed that 16.9% and 16.6% of the sheep dung C had decomposed, of which 3.5% and 2.8% was sequestrated in the soils of L. chinensis and A. frigida grasslands, respectively, while the remaining decomposed sheep dung was emitted as CO2. The cumulative amounts of C respired from dung treated soils during 152 days were 7–8 times higher than in the un-amended controls. In both grassland soils, ca. 60% of the evolved CO2 originated from the decomposing sheep dung and 40% from the native soil C. Priming effects of soil C decomposition were observed in both soils, i.e. 1.4 g and 1.6 g additional soil C kg−1 dry soil had been emitted as CO2 for the L. chinensis and A. frigida soils, respectively. Hence, the net C losses from L. chinensis and A. frigida soils were 0.6 g and 0.9 g C kg−1 soil, which was 2.6% and 7.0% of the total C in L. chinensis and A. frigida grasslands soils, respectively. Our results suggest that grazing of degraded Inner Mongolian pastures may cause a net soil C loss due to the positive priming effect, thereby accelerating soil deterioration. PMID:24236024

  14. Natural (13) C distribution in oil palm (Elaeis guineensis Jacq.) and consequences for allocation pattern.

    PubMed

    Lamade, Emmanuelle; Tcherkez, Guillaume; Darlan, Nuzul Hijri; Rodrigues, Rosario Lobato; Fresneau, Chantal; Mauve, Caroline; Lamothe-Sibold, Marlène; Sketriené, Diana; Ghashghaie, Jaleh

    2016-01-01

    Oil palm has now become one of the most important crops, palm oil representing nearly 25% of global plant oil consumption. Many studies have thus addressed oil palm ecophysiology and photosynthesis-based models of carbon allocation have been used. However, there is a lack of experimental data on carbon fixation and redistribution within palm trees, and important C-sinks have not been fully characterized yet. Here, we carried out extensive measurement of natural (13) C-abundance (δ(13) C) in oil palm tissues, including fruits at different maturation stages. We find a (13) C-enrichment in heterotrophic organs compared to mature leaves, with roots being the most (13) C-enriched. The δ(13) C in fruits decreased during maturation, reflecting the accumulation in (13) C-depleted lipids. We further used observed δ(13) C values to compute plausible carbon fluxes using a steady-state model of (13) C-distribution including metabolic isotope effects ((12) v/(13) v). The results suggest that fruits represent a major respiratory loss (≈39% of total tree respiration) and that sink organs such as fruits are fed by sucrose from leaves. That is, glucose appears to be a quantitatively important compound in palm tissues, but computations indicate that it is involved in dynamic starch metabolism rather that C-exchange between organs. PMID:26228944

  15. An overview of methods using 13C for improved compound identification in metabolomics and natural products

    PubMed Central

    Clendinen, Chaevien S.; Stupp, Gregory S.; Ajredini, Ramadan; Lee-McMullen, Brittany; Beecher, Chris; Edison, Arthur S.

    2015-01-01

    Compound identification is a major bottleneck in metabolomics studies. In nuclear magnetic resonance (NMR) investigations, resonance overlap often hinders unambiguous database matching or de novo compound identification. In liquid chromatography-mass spectrometry (LC-MS), discriminating between biological signals and background artifacts and reliable determination of molecular formulae are not always straightforward. We have designed and implemented several NMR and LC-MS approaches that utilize 13C, either enriched or at natural abundance, in metabolomics applications. For LC-MS applications, we describe a technique called isotopic ratio outlier analysis (IROA), which utilizes samples that are isotopically labeled with 5% (test) and 95% (control) 13C. This labeling strategy leads to characteristic isotopic patterns that allow the differentiation of biological signals from artifacts and yield the exact number of carbons, significantly reducing possible molecular formulae. The relative abundance between the test and control samples for every IROA feature can be determined simply by integrating the peaks that arise from the 5 and 95% channels. For NMR applications, we describe two 13C-based approaches. For samples at natural abundance, we have developed a workflow to obtain 13C–13C and 13C–1H statistical correlations using 1D 13C and 1H NMR spectra. For samples that can be isotopically labeled, we describe another NMR approach to obtain direct 13C–13C spectroscopic correlations. These methods both provide extensive information about the carbon framework of compounds in the mixture for either database matching or de novo compound identification. We also discuss strategies in which 13C NMR can be used to identify unknown compounds from IROA experiments. By combining technologies with the same samples, we can identify important biomarkers and corresponding metabolites of interest. PMID:26379677

  16. Natural isotope correction of MS/MS measurements for metabolomics and (13) C fluxomics.

    PubMed

    Niedenführ, Sebastian; Ten Pierick, Angela; van Dam, Patricia T N; Suarez-Mendez, Camilo A; Nöh, Katharina; Wahl, S Aljoscha

    2016-05-01

    Fluxomics and metabolomics are crucial tools for metabolic engineering and biomedical analysis to determine the in vivo cellular state. Especially, the application of (13) C isotopes allows comprehensive insights into the functional operation of cellular metabolism. Compared to single MS, tandem mass spectrometry (MS/MS) provides more detailed and accurate measurements of the metabolite enrichment patterns (tandem mass isotopomers), increasing the accuracy of metabolite concentration measurements and metabolic flux estimation. MS-type data from isotope labeling experiments is biased by naturally occurring stable isotopes (C, H, N, O, etc.). In particular, GC-MS(/MS) requires derivatization for the usually non-volatile intracellular metabolites introducing additional natural isotopes leading to measurements that do not directly represent the carbon labeling distribution. To make full useof LC- and GC-MS/MS mass isotopomer measurements, the influence of natural isotopes has to be eliminated (corrected). Our correction approach is analyzed for the two most common applications; (13) C fluxomics and isotope dilution mass spectrometry (IDMS) based metabolomics. Natural isotopes can have an impact on the calculated flux distribution which strongly depends on the substrate labeling and the actual flux distribution. Second, we show that in IDMS based metabolomics natural isotopes lead to underestimated concentrations that can and should be corrected with a nonlinear calibration. Our simulations indicate that the correction for natural abundance in isotope based fluxomics and quantitative metabolomics is essential for correct data interpretation. Biotechnol. Bioeng. 2016;113: 1137-1147. © 2015 Wiley Periodicals, Inc. PMID:26479486

  17. Body temperatures of modern and extinct vertebrates from 13C-18O bond abundances in bioapatite

    PubMed Central

    Eagle, Robert A.; Schauble, Edwin A.; Tripati, Aradhna K.; Tütken, Thomas; Hulbert, Richard C.; Eiler, John M.

    2010-01-01

    The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms and to reconstruct past climate. Here we report the application of a new type of geochemical measurement to bioapatite, a “clumped-isotope” paleothermometer, based on the thermodynamically driven preference for 13C and 18O to bond with each other within carbonate ions in the bioapatite crystal lattice. This effect is dependent on temperature but, unlike conventional stable isotope paleothermometers, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of 13C-18O bonds in the carbonate component of tooth bioapatite from modern specimens decreases with increasing body temperature of the animal, following a relationship between isotope “clumping” and temperature that is statistically indistinguishable from inorganic calcite. This result is in agreement with a theoretical model of isotopic ordering in carbonate ion groups in apatite and calcite. This thermometer constrains body temperatures of bioapatite-producing organisms with an accuracy of 1–2 °C. Analyses of fossilized tooth enamel of both Pleistocene and Miocene age yielded temperatures within error of those derived from similar modern taxa. Clumped-isotope analysis of bioapatite represents a new approach in the study of the thermophysiology of extinct species, allowing the first direct measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurement of clumped isotopes in phosphorites and fossils has the potential to reconstruct environmental temperatures. PMID:20498092

  18. Biosynthetic production of universally (13)C-labelled polyunsaturated fatty acids as reference materials for natural health product research.

    PubMed

    Le, Phuong Mai; Fraser, Catherine; Gardner, Graeme; Liang, Wei-Wan; Kralovec, Jaroslav A; Cunnane, Stephen C; Windust, Anthony J

    2007-09-01

    Long-chain polyunsaturated fatty acids (LCPUFA) including eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) have become important natural health products with numerous proven benefits related to brain function and cardiovascular health. Not only are omega-3 fatty acids available in a plethora of dietary supplements, but they are also increasingly being incorporated as triglycerides into conventional foods, including bread, milk, yoghurt and confectionaries. Recently, transgenic oil seed crops and livestock have been developed that enhance omega-3 fatty acid content. This diverse array of matrices presents a difficult analytical challenge and is compounded further by samples generated through clinical research. Stable isotope (13)C-labelled LCPUFA standards offer many advantages as research tools because they may be distinguished from their naturally abundant counterparts by mass spectrometry and directly incorporated as internal standards into analytical procedures. Further, (13)C-labelled LCPUFAs are safe to use as metabolic tracers to study uptake and metabolism in humans. Currently, (13)C-labelled LCPUFAs are expensive, available in limited supply and not in triglyceride form. To resolve these issues, marine heterotrophic microorganisms are being isolated and screened for LCPUFA production with a view to the efficient biosynthetic production of U-(13)C-labelled fatty acids using U-(13)C glucose as a carbon source. Of 37 isolates obtained, most were thraustochytrids, and either DHA or omega-6 docosapentaenoic acid (22:5n-6) were produced as the major LCPUFA. The marine protist Hyalochlorella marina was identified as a novel source of EPA and omega-3 docosapentaenoic acid (22:5n-3). As proof of principle, gram-level production of (13)C-labelled DHA has been achieved with high chemical purity ( >99%) and high (13)C incorporation levels (>90%), as confirmed by NMR and MS analyses. Finally, U-(13)C-DHA was enzymatically re-esterified to

  19. 1H to 13C Energy Transfer in Solid State NMR Spectroscopy of Natural Organic Systems

    NASA Astrophysics Data System (ADS)

    Berns, Anne E.; Conte, Pellegrino

    2010-05-01

    Cross polarization (CP) magic angle spinning (MAS) 13C-NMR spectroscopy is a solid state NMR technique widely used to study chemical composition of organic materials with low or no solubility in the common deuterated solvents used to run liquid state NMR experiments. Based on the magnetization transfer from abundant nuclei (with spin of 1 -2) having a high gyromagnetic ratio (γ), such as protons, to the less abundant 13C nuclei with low γ values, 13C-CPMAS NMR spectroscopy is often applied in environmental chemistry to obtain quantitative information on the chemical composition of natural organic matter (NOM) (Conte et al., 2004), although its quantitative assessment is still matter of heavy debates. Many authors (Baldock et al., 1997; Conte et al., 1997, 2002; Dria et al., 2002; Kiem et al., 2000; Kögel-Knabner, 2000; Preston, 2001), reported that the application of appropriate instrument setup as well as the use of special pulse sequences and correct spectra elaboration may provide signal intensities that are directly proportional to the amount of nuclei creating a NMR signal. However, many other papers dealt with the quantitative unsuitability of 13C-CPMAS NMR spectroscopy. Among those, Mao et al. (2000), Smernik and Oades (2000 a,b), and Preston (2001) reported that cross-polarized NMR techniques may fail in a complete excitation of the 13C nuclei. In fact, the amount of observable carbons via 13C-CPMAS NMR spectroscopy appeared, in many cases, lower than that measured by a direct observation of the 13C nuclei. As a consequence, cross-polarized NMR techniques may provide spectra where signal distribution may not be representative of the quantitative distribution of the different natural organic matter components. Cross-polarization is obtained after application of an initial 90° x pulse on protons and a further spin lock pulse (along the y axis) having a fixed length (contact time) for both nuclei (1H and 13C) once the Hartmann-Hahn condition is matched

  20. Choice of dietary protein of vegetarians and omnivores is reflected in their hair protein 13C and 15N abundance.

    PubMed

    Petzke, Klaus J; Boeing, Heiner; Metges, Cornelia C

    2005-01-01

    Stable isotopic (15N, 13C) composition of tissues depends on isotopic pattern of food sources. We investigated whether the isotopic compositions of human hair protein and amino acids reflect the habitual dietary protein intake. Hair samples were analyzed from 100 omnivores (selected randomly out of the 1987-1988 German nutrition survey VERA), and from 15 ovo-lacto-vegetarians (OLV), and from 6 vegans recruited separately. Hair bulk and amino acid specific isotopic compositions were analyzed by isotope-ratio mass spectrometry (EA/IRMS and GC/C/IRMS, respectively) and the results were correlated with data of the 7 day dietary records. Hair bulk 15N and 13C abundances clearly reflect the particular eating habits. Vegans can be distinguished from OLV and both are significantly distinct from omnivores in both 15N and 13C abundances. 15N and 13C abundances rose with a higher proportion of animal to total protein intake (PAPI). Individual proportions of animal protein consumption (IPAP) were calculated using isotopic abundances and a linear regression model using animal protein consumption data of vegans (PAPI = 0) and omnivores (mean PAPI = 0.639). IPAP values positively correlated with the intake of protein, meat, meat products, and animal protein. Distinct patterns for hair amino acid specific 15N and 13C abundances were measured but with lower resolution between food preference groups compared with bulk values. In conclusion, hair 13C and 15N values both reflected the extent of animal protein consumption. Bulk isotopic abundance of hair can be tested for future use in the validation of dietary assessment methods. PMID:15880664

  1. Comparing Soil and Bison δ13C to Field Estimates of C4 Plant Abundances in North America

    NASA Astrophysics Data System (ADS)

    Griffith, D.; Still, C. J.; Cotton, J.; Powell, B.

    2015-12-01

    Stable carbon isotope data (i.e., δ13C) from soils and herbivore tissue are commonly used as a proxy for the relative abundance of C4 and C3 plants at a site. These data are also increasingly used to represent other climatologically relevant properties of vegetated environments, such as productivity, aridity, water use efficiency, and tree cover. The δ13C values of soils and herbivore tissues are generally assumed to resemble their source vegetation, after accounting for diverse fractionation processes during litter decomposition and tissue metabolism and turnover. However, δ13C values have rarely been compared to source vegetation at a regional to continental scale. As a result, the quality of δ13C as a proxy has not been thoroughly evaluated, and the importance of modifying factors have not been assessed at biogeographically relevant scales. To address some of these issues, we combined three multi-source datasets from North America: herbaceous C4 plant abundances from thousands of vegetation plots, hundreds of soil δ13C measurements, and hundreds of bison collagen, hair, and enamel δ13C data (tissues with different turnover rates). These datasets were resampled to common grid for comparison. A stronger relationship with C4 vegetation existed for bison as compared to soil δ13C. To determine which factors might explain deviations in the vegetation plot and isotopic data, we used statistical models to quantify the influence of soil variables, mean annual precipitation and temperature, tree cover, presence of invasives, and fire frequency in conjunction with plot-based C4 abundance data. Our bison model was only improved by the addition of invasives. In contrast, our soil model was significantly improved when accounting for tree cover (C3 vegetation and shade), precipitation, various soil parameters, and invasive grasses, suggesting that soils are more likely to be biased from source vegetation in ways that could influence interpretation as a proxy at broad

  2. Galactic chemical evolution and solar s-process abundances: Dependence on the {sup 13}C-pocket structure

    SciTech Connect

    Bisterzo, S.; Travaglio, C.; Gallino, R.; Wiescher, M.; Käppeler, F. E-mail: sarabisterzo@gmail.com

    2014-05-20

    We study the s-process abundances (A ≳ 90) at the epoch of the solar system formation. Asymptotic giant branch yields are computed with an updated neutron capture network and updated initial solar abundances. We confirm our previous results obtained with a Galactic chemical evolution (GCE) model: (1) as suggested by the s-process spread observed in disk stars and in presolar meteoritic SiC grains, a weighted average of s-process strengths is needed to reproduce the solar s distribution of isotopes with A > 130; and (2) an additional contribution (of about 25%) is required in order to represent the solar s-process abundances of isotopes from A = 90 to 130. Furthermore, we investigate the effect of different internal structures of the {sup 13}C pocket, which may affect the efficiency of the {sup 13}C(α, n){sup 16}O reaction, the major neutron source of the s process. First, keeping the same {sup 13}C profile adopted so far, we modify by a factor of two the mass involved in the pocket; second, we assume a flat {sup 13}C profile in the pocket, and we test again the effects of the variation of the mass of the pocket. We find that GCE s predictions at the epoch of the solar system formation marginally depend on the size and shape of the {sup 13}C pocket once a different weighted range of {sup 13}C-pocket strengths is assumed. We obtain that, independently of the internal structure of the {sup 13}C pocket, the missing solar system s-process contribution in the range from A = 90 to 130 remains essentially the same.

  3. Galactic Chemical Evolution and Solar s-process Abundances: Dependence on the 13C-pocket Structure

    NASA Astrophysics Data System (ADS)

    Bisterzo, S.; Travaglio, C.; Gallino, R.; Wiescher, M.; Käppeler, F.

    2014-05-01

    We study the s-process abundances (A >~ 90) at the epoch of the solar system formation. Asymptotic giant branch yields are computed with an updated neutron capture network and updated initial solar abundances. We confirm our previous results obtained with a Galactic chemical evolution (GCE) model: (1) as suggested by the s-process spread observed in disk stars and in presolar meteoritic SiC grains, a weighted average of s-process strengths is needed to reproduce the solar s distribution of isotopes with A > 130; and (2) an additional contribution (of about 25%) is required in order to represent the solar s-process abundances of isotopes from A = 90 to 130. Furthermore, we investigate the effect of different internal structures of the 13C pocket, which may affect the efficiency of the 13C(α, n)16O reaction, the major neutron source of the s process. First, keeping the same 13C profile adopted so far, we modify by a factor of two the mass involved in the pocket; second, we assume a flat 13C profile in the pocket, and we test again the effects of the variation of the mass of the pocket. We find that GCE s predictions at the epoch of the solar system formation marginally depend on the size and shape of the 13C pocket once a different weighted range of 13C-pocket strengths is assumed. We obtain that, independently of the internal structure of the 13C pocket, the missing solar system s-process contribution in the range from A = 90 to 130 remains essentially the same.

  4. Abundance Anomaly of the 13C Isotopic Species of c-C3H2 in the Low-mass Star Formation Region L1527

    NASA Astrophysics Data System (ADS)

    Yoshida, Kento; Sakai, Nami; Tokudome, Tomoya; López-Sepulcre, Ana; Watanabe, Yoshimasa; Takano, Shuro; Lefloch, Bertrand; Ceccarelli, Cecilia; Bachiller, Rafael; Caux, Emmanuel; Vastel, Charlotte; Yamamoto, Satoshi

    2015-07-01

    The rotational spectral lines of c-C3H2 and two kinds of the 13C isotopic species, c-{}13{{CCCH}}2 ({C}2v symmetry) and c-{{CC}}13{{CH}}2 (Cs symmetry), have been observed in the 1–3 mm band toward the low-mass star-forming region L1527. We have detected 7, 3, and 6 lines of c-C3H2, c-{}13{{CCCH}}2, and c-{{CC}}13{{CH}}2, respectively, with the Nobeyama 45 m telescope and 34, 6, and 13 lines, respectively, with the IRAM 30 m telescope, where seven, two, and two transitions, respectively, are observed with both telescopes. With these data, we have evaluated the column densities of the normal and 13C isotopic species. The [c-C3H2]/[c-{}13{{CCCH}}2] ratio is determined to be 310 ± 80, while the [c-C3H2]/[c-{{CC}}13{{CH}}2] ratio is determined to be 61 ± 11. The [c-C3H2]/[c-{}13{{CCCH}}2] and [c-C3H2]/[c-{{CC}}13{{CH}}2] ratios expected from the elemental 12C/13C ratio are 60–70 and 30–35, respectively, where the latter takes into account the statistical factor of 2 for the two equivalent carbon atoms in c-C3H2. Hence, this observation further confirms the dilution of the 13C species in carbon-chain molecules and their related molecules, which are thought to originate from the dilution of 13C+ in the gas-phase C+ due to the isotope exchange reaction: {}13{{{C}}}++{CO}\\to {}13{CO}+{{{C}}}+. Moreover, the abundances of the two 13C isotopic species are different from each other. The ratio of c-{}13{{CCCH}}2 species relative to c-{{CC}}13{{CH}}2 is determined to be 0.20 ± 0.05. If 13C were randomly substituted for the three carbon atoms, the [c-{}13{{CCCH}}2]/[c-{{CC}}13{{CH}}2] ratio would be 0.5. Hence, the observed ratio indicates that c-{{CC}}13{{CH}}2 exists more favorably. Possible origins of the different abundances are discussed. Based on observations carried out with the IRAM 30 m Telescope and the NRO 45 m Telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). NRO is a branch of the National Astronomical Observatory of Japan

  5. Identification of natural metabolites in mixture: a pattern recognition strategy based on (13)C NMR.

    PubMed

    Hubert, Jane; Nuzillard, Jean-Marc; Purson, Sylvain; Hamzaoui, Mahmoud; Borie, Nicolas; Reynaud, Romain; Renault, Jean-Hugues

    2014-03-18

    Because of their highly complex metabolite profile, the chemical characterization of bioactive natural extracts usually requires time-consuming multistep purification procedures to achieve the structural elucidation of pure individual metabolites. The aim of the present work was to develop a dereplication strategy for the identification of natural metabolites directly within mixtures. Exploiting the polarity range of metabolites, the principle was to rapidly fractionate a multigram quantity of a crude extract by centrifugal partition extraction (CPE). The obtained fractions of simplified chemical composition were subsequently analyzed by (13)C NMR. After automatic collection and alignment of (13)C signals across spectra, hierarchical clustering analysis (HCA) was performed for pattern recognition. As a result, strong correlations between (13)C signals of a single structure within the mixtures of the fraction series were visualized as chemical shift clusters. Each cluster was finally assigned to a molecular structure with the help of a locally built (13)C NMR chemical shift database. The proof of principle of this strategy was achieved on a simple model mixture of commercially available plant secondary metabolites and then applied to a bark extract of the African tree Anogeissus leiocarpus Guill. & Perr. (Combretaceae). Starting from 5 g of this genuine extract, the fraction series was generated by CPE in only 95 min. (13)C NMR analyses of all fractions followed by pattern recognition of (13)C chemical shifts resulted in the unambiguous identification of seven major compounds, namely, sericoside, trachelosperogenin E, ellagic acid, an epimer mixture of (+)-gallocatechin and (-)-epigallocatechin, 3,3'-di-O-methylellagic acid 4'-O-xylopyranoside, and 3,4,3'-tri-O-methylflavellagic acid 4'-O-glucopyranoside. PMID:24555703

  6. Four-Component Relativistic DFT Calculations of (13)C Chemical Shifts of Halogenated Natural Substances.

    PubMed

    Casella, Girolamo; Bagno, Alessandro; Komorovsky, Stanislav; Repisky, Michal; Saielli, Giacomo

    2015-12-14

    We have calculated the (13)C NMR chemical shifts of a large ensemble of halogenated organic molecules (81 molecules for a total of 250 experimental (13)C NMR data at four different levels of theory), ranging from small rigid organic compounds, used to benchmark the performance of various levels of theory, to natural substances of marine origin with conformational degrees of freedom. Carbon atoms bonded to heavy halogen atoms, particularly bromine and iodine, are known to be rather challenging when it comes to the prediction of their chemical shifts by quantum methods, due to relativistic effects. In this paper, we have applied the state-of-the-art four-component relativistic density functional theory for the prediction of such NMR properties and compared the performance with two-component and nonrelativistic methods. Our results highlight the necessity to include relativistic corrections within a four-component description for the most accurate prediction of the NMR properties of halogenated organic substances. PMID:26541625

  7. Economical synthesis of 13C-labeled opiates, cocaine derivatives and selected urinary metabolites by derivatization of the natural products.

    PubMed

    Karlsen, Morten; Liu, Huiling; Johansen, Jon Eigill; Hoff, Bård Helge

    2015-01-01

    The illegal use of opiates and cocaine is a challenge world-wide, but some derivatives are also valuable pharmaceuticals. Reference samples of the active ingredients and their metabolites are needed both for controlling administration in the clinic and to detect drugs of abuse. Especially, (13)C-labeled compounds are useful for identification and quantification purposes by mass spectroscopic techniques, potentially increasing accuracy by minimizing ion alteration/suppression effects. Thus, the synthesis of [acetyl-(13)C4]heroin, [acetyl-(13)C4-methyl-(13)C]heroin, [acetyl-(13)C2-methyl-(13)C]6-acetylmorphine, [N-methyl-(13)C-O-metyl-(13)C]codeine and phenyl-(13)C6-labeled derivatives of cocaine, benzoylecgonine, norcocaine and cocaethylene was undertaken to provide such reference materials. The synthetic work has focused on identifying (13)C atom-efficient routes towards these derivatives. Therefore, the (13)C-labeled opiates and cocaine derivatives were made from the corresponding natural products. PMID:25816077

  8. (1) H and (13) C NMR data on natural and synthetic capsaicinoids.

    PubMed

    Gómez-Calvario, Víctor; Garduño-Ramírez, María Luisa; León-Rivera, Ismael; Rios, María Yolanda

    2016-04-01

    Capsaicinoids are the compounds responsible for the pungency of chili peppers. These substances have attracted the attention of many research groups in recent decades because of their antinociceptive, analgesic, anti-inflammatory, and anti-obesity properties, among others. There are nearly 160 capsaicinoids reported in the literature. Approximately 25 of them are natural products, while the rest are synthetic or semi-synthetic products. A large amount of NMR data for the capsaicinoids is dispersed throughout literature. Therefore, there is a need to organize all this NMR data in a systematic and orderly way. This review summarizes the (1) H and (13) C NMR data on 159 natural and synthetic capsaicinoids, with a brief discussion of some typical and relevant aspects of these NMR data. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26626418

  9. 13C NMR Metabolomics: INADEQUATE Network Analysis

    PubMed Central

    Clendinen, Chaevien S.; Pasquel, Christian; Ajredini, Ramadan; Edison, Arthur S.

    2015-01-01

    The many advantages of 13C NMR are often overshadowed by its intrinsically low sensitivity. Given that carbon makes up the backbone of most biologically relevant molecules, 13C NMR offers a straightforward measurement of these compounds. Two-dimensional 13C-13C correlation experiments like INADEQUATE (incredible natural abundance double quantum transfer experiment) are ideal for the structural elucidation of natural products and have great but untapped potential for metabolomics analysis. We demonstrate a new and semi-automated approach called INETA (INADEQUATE network analysis) for the untargeted analysis of INADEQUATE datasets using an in silico INADEQUATE database. We demonstrate this approach using isotopically labeled Caenorhabditis elegans mixtures. PMID:25932900

  10. Effect of photosynthesis on the abundance of 18O13C16O in atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Hofmann, Magdalena E. G.; Pons, Thijs L.; Ziegler, Martin; Lourens, Lucas J.; Röckmann, Thomas

    2016-04-01

    The abundance of the isotopologue 18O13C16O (Δ47) in atmospheric air is a promising new tracer for the atmospheric carbon cycle (Eiler and Schauble, 2004; Affek and Eiler, 2006; Affek et al., 2007). The large gross fluxes in CO2 between the atmosphere and biosphere are supposed to play a major role in controlling its abundance. Eiler and Schauble (2004) set up a box model describing the effect of air-leaf interaction on the abundance of 18O13C16O in atmospheric air. The main assumption is that the exchange between CO2 and water within the mesophyll cells will imprint a Δ47 value on the back-diffusing CO2 that reflects the leaf temperature. Additionally, kinetic effects due to CO2 diffusion into and out of the stomata are thought to play a role. We investigated the effect of photosynthesis on the residual CO2 under controlled conditions using a leaf chamber set-up to quantitatively test the model assumptions suggested by Eiler and Schauble (2004). We studied the effect of photosynthesis on the residual CO2 using two C3 and one C4 plant species: (i) sunflower (Helianthus annuus), a C3 species with a high leaf conductance for CO2 diffusion, (ii) ivy (Hedera hibernica), a C3 species with a low conductance, and (iii), maize (Zea mays), a species with the C4 photosynthetic pathway. We also investigated the effect of different light intensities (photosynthetic photon flux density of 200, 700 and 1800 μmol m2s‑1), and thus, photosynthetic rate in sunflower and maize. A leaf was mounted in a cuvette with a transparent window and an adjustable light source. The air inside was thoroughly mixed, making the composition of the outgoing air equal to the air inside. A gas-mixing unit was attached at the entrance of the cuvette that mixed air with a high concentration of scrambled CO2 with a Δ47 value of 0 to 0.1‰ with CO2 free air to set the CO2 concentration of ingoing air at 500 ppm. The flow rate through the cuvette was adjusted to the photosynthetic activity of the

  11. The Nature of Carbonate and Organic δ13C Covariance Through Geological Time

    NASA Astrophysics Data System (ADS)

    Oehlert, A. M.; Swart, P. K.

    2014-12-01

    Significant evolutionary, climatic, and oceanographic events in Earth history are often accompanied by excursions in the carbon isotope composition (δ13C) of marine carbonates and co-occurring sedimentary organic material. The observation of synchronous excursions in the δ13C values of marine carbonates and coeval organic matter is commonly thought to prove that the deposit has not been altered by diagenesis, and that the variations in the δ13C records are the result of a significant change in global carbon cycling. Furthermore, this model suggests that the covariance of carbonate and organic δ13C records is driven only by changes in the δ13C value of the dissolved inorganic carbon in the surface waters of the ocean. However, recent work suggests that there may be at least two alternate models for generating covariance between carbonate and organic δ13C values in the geologic record. One of the models invokes sea-level driven syndepositional mixing between isotopically distinct sources of carbonate and organic material to produce positive covariance between carbonate and organic δ13C values. The second model suggests that post-depositional alteration to the carbonate δ13C values during meteoric diagenesis, in concert with concurrent contributions of terrestrial organic material during subaerial exposure, can also produce co-occurring negative excursions with tightly covariant δ13C records. In contrast to earlier interpretations of covariant δ13C values, these models suggest that both syndepositional and post-depositional factors can significantly influence the relationship between carbonate and organic δ13C values in a variety of depositional environments. The implications for reconstructions of ancient global carbon cycle events will be explored within the context of these three models, and their relative importance throughout geologic time will be discussed.

  12. Diagonal free homonuclear correlation using heteronuclei at natural abundance.

    PubMed

    Baishya, Bikash

    2015-07-01

    Homonuclear correlated spectroscopy such as COSY and TOCSY provides crucial structural information. In all homonuclear correlation, the most intense peaks are represented by the diagonal. As a result, the useful cross peaks close to the diagonal get obscured by the huge tails of diagonal peaks. Herein, we show that by editing the proton magnetization by a 13C nucleus in natural abundance, it is possible to eliminate the inphase coherence or untransferred magnetization that leads to the diagonal peak while retaining the antiphase coherence or transferred magnetization required for creation of cross peak. After the coherence transfer step, the untransferred magnetization directly attached to 13C evolves under one bond heteronuclear coupling while the transferred transverse magnetization directly attached to remote 12C does not. As a result, the untransferred magnetization directly attached to 13C can be converted to an unobservable heteronuclear multiple quantum coherence leading to a diagonal free correlated spectrum with a sensitivity penalty of two orders of magnitude but comparable to HSQC kind of experiments at natural abundance. The method demonstrated for COSY and TOCSY allows all proton-proton correlations to be observed except the geminal proton-proton correlations. Further, protons directly attached to heteronuclei other than 13C must be scalar coupled to protons directly attached to 13C to have a detectable cross peak. PMID:26001137

  13. Chemical structural studies of natural lignin by dipolar dephasing solid-state 13C nuclear magnetic resonance

    USGS Publications Warehouse

    Hatcher, P.G.

    1987-01-01

    Two natural lignins, one from a gymnosperm wood the other from angiosperm wood, were examined by conventional solid-state and dipolar dephasing 13C nuclear magnetic resonance (NMR) techniques. The results obtained from both techniques show that the structure of natural lignins is consistent with models of softwood and hardwood lignin. The dipolar dephasing NMR data provide a measure of the degree of substitution on aromatic rings which is consistent with the models. ?? 1987.

  14. The carbon abundance and 12C/13C isotopic ratio in the atmosphere of Arcturus from 2.3 µm CO bands

    NASA Astrophysics Data System (ADS)

    Pavlenko, Ya. V.

    2008-09-01

    We have modeled absorption lines of the 12CO and 13CO (Δ υ = 2) molecular bands at λλ 2.29 2.45 µm in the spectrum of Arcturus (K2III). A grid of model atmospheres and synthetic spectra were computed for the red giant using T eff = 4300, log g = 1.5, and the elemental abundances of Peterson et al. (1993), with the exception of the abundances of carbon, log N(C), and oxygen, log N(O) and the carbon isotopic ratio, 12C/13C, which were varied in our computations. The computed spectra were compared to the observed spectrum of Arcturus from the atlas of Hinkle et al. (1976). The best fit between the synthetic and observed spectra is achieved for log N(C) = -3.78, 12C/13C = 8 ± 0.5. We discuss the dependence of 12C/13C on log N(C) and log N(O) in the atmosphere of the red giant.

  15. NMR characterization of 13C-benzene sorbed to natural and prepared charcoals.

    PubMed

    Smernik, Ronald J; Kookana, Rai S; Skjemstad, Jan O

    2006-03-15

    We investigated how the NMR properties of uniformly 13C-labeled benzene molecules are influenced by sorption to charcoals produced in the laboratory and collected from the field following wildfires. Uniformly 13C-labeled benzene was sorbed to two charcoals produced in the laboratory at 450 and 850 degrees C. The chemical shift of benzene sorbed to the higher-temperature charcoal was 5-6 ppm lower than that of benzene sorbed to the lower-temperature charcoal. This difference was attributed to stronger diamagnetic ring currents (which cause a shift to lower ppm values) in the more condensed or "graphitic" high-temperature charcoal. The chemical shift of benzene sorbed to two charcoals collected from the field following wildfires indicated a degree of charcoal graphitization intermediate between that of the two laboratory-prepared charcoals. Variable contact time and dipolar dephasing experiments showed that the molecular mobility of sorbed benzene molecules increased with increasing charcoal graphitization, and also increased with increasing benzene concentration. We propose that the chemical shift displacement of molecules sorbed to charcoal could be used to identify molecules sorbed to black carbon in heterogeneous matrixes such as soils and sediments, and to establish how condensed or "graphitic" the black carbon is. PMID:16570595

  16. 13 ENDOR studies of organic radicals in natural isotopic abundance

    NASA Astrophysics Data System (ADS)

    Kirste, Burkhard

    13C ENDOR studies of phenoxyls, galvinoxyls, triphenylmethyl radicals, nitroxides, and cyclosilane and semiquinone radical anions with natural isotopic distribution are reported. The method is described, and it is shown that 13C coupling constants can be measured precisely; in favorable cases even the determination of signs is possible by general TRIPLE resonance. Studies of the relaxation behavior of 13C ENDOR signals or measurements of hyperfine shifts in liquid-crystalline solutions yield information about dipolar hyperfine interactions and hence π spin populations which is of aid in assignments to molecular positions. Complete sets of 13C coupling constants have been determined for 2,4,6-tri- tert-butylphenoxyl and Coppinger's radical. For the central carbon atoms of tert-butyl groups, a Q parameter of Qτ-Bu C = -34 MHz is proposed, and for a 29Si atom in trimethylsilyl groups, QTMSSi = +49 MHz. Favorable conditions for natural-abundance 13C ENDOR experiments, e.g., small hyperfine anisotropies and use of deuterated compounds, and limitations of the method are discussed.

  17. Accurate quantitative 13C NMR spectroscopy: repeatability over time of site-specific 13C isotope ratio determination.

    PubMed

    Caytan, Elsa; Botosoa, Eliot P; Silvestre, Virginie; Robins, Richard J; Akoka, Serge; Remaud, Gérald S

    2007-11-01

    The stability over time (repeatability) for the determination of site-specific 13C/12C ratios at natural abundance by quantitative 13C NMR spectroscopy has been tested on three probes: enriched bilabeled [1,2-13C2]ethanol; ethanol at natural abundance; and vanillin at natural abundance. It is shown in all three cases that the standard deviation for a series of measurements taken every 2-3 months over periods between 9 and 13 months is equal to or smaller than the standard deviation calculated from 5-10 replicate measurements made on a single sample. The precision which can be achieved using the present analytical 13C NMR protocol is higher than the prerequisite value of 1-2 per thousand for the determination of site-specific 13C/12C ratios at natural abundance (13C-SNIF-NMR). Hence, this technique permits the discrimination of very small variations in 13C/12C ratios between carbon positions, as found in biogenic natural products. This observed stability over time in 13C NMR spectroscopy indicates that further improvements in precision will depend primarily on improved signal-to-noise ratio. PMID:17900175

  18. Determining carbon-carbon connectivities in natural abundance organic powders using dipolar couplings.

    PubMed

    Dekhil, Myriam; Mollica, Giulia; Bonniot, Tristan Texier; Ziarelli, Fabio; Thureau, Pierre; Viel, Stéphane

    2016-06-30

    We present a solid-state NMR methodology capable of investigating the carbon skeleton of natural abundance organic powders. The methodology is based on the (13)C-(13)C dipolar coupling interaction and allows carbon-carbon connectivities to be unambiguously established for a wide range of organic solids. This methodology is particularly suitable for disordered solids, such as natural or synthetic macromolecules, which cannot be studied using conventional diffraction or NMR techniques. PMID:27319808

  19. A paleothermometer based on abundances of 13C-18O bonds in bioapatite: Calibration and reconstruction of the body temperatures of extinct Cenozoic mammals and Mesozoic dinosaurs

    NASA Astrophysics Data System (ADS)

    Eagle, R.; Schauble, E. A.; Tripati, A. K.; Fricke, H. C.; Tuetken, T.; Eiler, J. M.

    2009-12-01

    The stable isotope compositions of biologically precipitated apatite in bone, teeth, and scales are widely used to obtain information on the diet, behavior, and physiology of extinct organisms, and to reconstruct past climate in terrestrial and marine settings. Here we report the application of a new type of geochemical measurement to bioapatite, a ‘clumped isotope’ thermometer based on the thermodynamically driven preference for 13C and 18O to bond with each other within carbonate ions in the crystal lattice of apatite. This effect is dependent on temperature but unlike conventional stable isotope paleotemperature proxies, is independent from the isotopic composition of water from which the mineral formed. We show that the abundance of 13C-18O bonds in the carbonate component of apatite from modern teeth is proportional to the body temperature of the organism, with an accuracy of 1-2oC, and that the empirical calibration is supported by a theoretical model of isotopic ordering. We also report initial paleothermometry results from analyses of Cenozoic fossil mammal teeth and Mesozoic dinosaur teeth. Therefore, clumped isotope analysis of bioapatite represents a new approach in the study of the physiology of extinct species by allowing the first relatively assumption-free measurement of their body temperatures. It will also open new avenues in the study of paleoclimate, as the measurements of clumped isotopes in apatite from fossils, such as conodonts and brachiopods, as well as phosphorites, have the potential to record environmental temperatures.

  20. /sup 13/C spin diffusion of adamantane

    SciTech Connect

    Bronniman, C.E.; Szeverenyi, N.M.; Maciel, G.E.

    1983-10-15

    Two-dimensional exchange spectroscopy of natural abundance /sup 13/C--/sup 13/C spin diffusion in solid adamantane illustrates the influence that /sup 13/C--/sup 1/H dipole--dipole coupling exerts on /sup 13/C spin diffusion by determining spectral overlap in the /sup 13/C system. 2D /sup 13/C spectra were obtained for several values of mixing time tau/sub m/ and compared with spectra calculated in the limit of nearest-neighbor coupling. Good agreement is obtained for short tau/sub m/, during which the equilibration of neighboring spins dominates. For longer tau/sub m/, slower spin diffusion that is not acounted for by the simple model is seen; after nearest-neighbor spins equilibrate, communication over larger distances produces further mixing. It is possible to modify spin diffusion rates by altering experimental conditions, e.g., magic-angle spinning, low-power /sup 1/H decoupling, or spin locking /sup 13/C in the rotating frame during tau/sub m/.

  1. Short-Term Effects of Tillage Practices on Soil Organic Carbon Turnover Assessed by δ13C Abundance in Particle-Size Fractions of Black Soils from Northeast China

    PubMed Central

    Zhang, Xiaoping; Chen, Xuewen

    2014-01-01

    The combination of isotope trace technique and SOC fractionation allows a better understanding of SOC dynamics. A five-year tillage experiment consisting of no-tillage (NT) and mouldboard plough (MP) was used to study the changes in particle-size SOC fractions and corresponding δ13C natural abundance to assess SOC turnover in the 0–20 cm layer of black soils under tillage practices. Compared to the initial level, total SOC tended to be stratified but showed a slight increase in the entire plough layer under short-term NT. MP had no significant impacts on SOC at any depth. Because of significant increases in coarse particulate organic carbon (POC) and decreases in fine POC, total POC did not remarkably decrease under NT and MP. A distinct increase in silt plus clay OC occurred in NT plots, but not in MP plots. However, the δ13C abundances of both coarse and fine POC increased, while those of silt plus clay OC remained almost the same under NT. The C derived from C3 plants was mainly associated with fine particles and much less with coarse particles. These results suggested that short-term NT and MP preferentially enhanced the turnover of POC, which was considerably faster than that of silt plus clay OC. PMID:25162052

  2. Measurement of 13CO2 in expired air as an index of compliance to a high carbohydrate diet naturally enriched in 13C.

    PubMed

    Gay, L J; Schutz, Y; DiVetta, V; Schneiter, P; Tappy, L; Jéquier, E

    1994-09-01

    The aim of this study was to determine whether breath 13CO2 measurements could be used to assess the compliance to a diet containing carbohydrates naturally enriched in 13C. The study was divided into two periods: Period 1 (baseline of 4 days) with low 13C/12C ratio carbohydrates. Period 2 (5 days) isocaloric diet with a high 13C/12C ratio (corn, cane sugar, pineapple, millet) carbohydrates. Measurements were made of respiratory gas exchange by indirect calorimetry, urinary nitrogen excretion and breath 13CO2 every morning in post-absorptive conditions, both in resting state and during a 45-min low intensity exercise (walking on a treadmill). The subjects were 10 healthy lean women (BMI 20.4 +/- 1.7 kg/m2, % body fat 24.4 +/- 1.3%), the 13C enrichment of oxidized carbohydrate and breath 13CO2 were compared to the enrichment of exogenous dietary carbohydrates. At rest the enrichment of oxidized carbohydrate increased significantly after one day of 13C carbohydrate enriched diet and reached a steady value (103 +/- 16%) similar to the enrichment of exogenous carbohydrates. During exercise, the 13C enrichment of oxidized carbohydrate remained significantly lower (68 +/- 17%) than that of dietary carbohydrates. The compliance to a diet with a high content of carbohydrates naturally enriched in 13C may be assessed from the measurement of breath 13CO2 enrichment combined with respiratory gas exchange in resting, postabsorptive conditions. PMID:7812411

  3. A survey of methane isotope abundance (14C, 13C, 2H) from five nearshore marine basins that reveals unusual radiocarbon levels in subsurface waters

    NASA Astrophysics Data System (ADS)

    Kessler, J. D.; Reeburgh, W. S.; Valentine, D. L.; Kinnaman, F. S.; Peltzer, E. T.; Brewer, P. G.; Southon, J.; Tyler, S. C.

    2008-12-01

    Methane (CH4) in the subsurface ocean is often supersaturated compared to equilibrium with the modern atmosphere. In order to investigate sources of CH4 to the subsurface ocean, isotope surveys (14C-CH4,δ13C-CH4, δ2H-CH4) were conducted at five locations: Skan Bay (SB), Santa Barbara Basin (SBB), Santa Monica Basin (SMB), Cariaco Basin (CB), and the Guaymas Basin (GB). Depth distributions of CH4 concentration and isotopic abundance were determined for both the sediment and water column at the SB, SBB, SMB, and CB sites; CH4 emitted from seeps on the continental shelf adjacent to the SBB as well as seeps and decomposing clathrate hydrates in the GB was also collected, purified, and analyzed. Methane isotope distributions in the sediments were consistent with known methanogenic and methanotrophic activity; seep- and clathrate-hydrate-derived CH4 was found to be depleted in radiocarbon. However, surprising results were obtained in the water column at all sites investigated. In SB the radiocarbon content of the subsurface CH4 concentration maximum was on average 41% less than its suspected sediment CH4 source, suggesting CH4 seepage in the bay. In the SBB, SMB, and CB, the 14C-CH4 contents in the subsurface ocean were 1.2 to 3.6 times greater than modern carbon quantities suggesting a source of 14C from atmospheric nuclear weapons testing, nuclear power plant effluents, or cosmogenic isotope production.

  4. The {sup 13}C-pocket structure in AGB models: constraints from zirconium isotope abundances in single mainstream SiC grains

    SciTech Connect

    Liu, Nan; Davis, Andrew M.; Pellin, Michael J.; Gallino, Roberto; Bisterzo, Sara; Savina, Michael R.

    2014-06-20

    We present postprocess asymptotic giant branch (AGB) nucleosynthesis models with different {sup 13}C-pocket internal structures to better explain zirconium isotope measurements in mainstream presolar SiC grains by Nicolussi et al. and Barzyk et al. We show that higher-than-solar {sup 92}Zr/{sup 94}Zr ratios can be predicted by adopting a {sup 13}C-pocket with a flat {sup 13}C profile, instead of the previous decreasing-with-depth {sup 13}C profile. The improved agreement between grain data for zirconium isotopes and AGB models provides additional support for a recent proposal of a flat {sup 13}C profile based on barium isotopes in mainstream SiC grains by Liu et al.

  5. The 13C-Pocket Structure in AGB Models: Constraints from Zirconium Isotope Abundances in Single Mainstream SiC Grains

    NASA Astrophysics Data System (ADS)

    Liu, Nan; Gallino, Roberto; Bisterzo, Sara; Davis, Andrew M.; Savina, Michael R.; Pellin, Michael J.

    2014-06-01

    We present postprocess asymptotic giant branch (AGB) nucleosynthesis models with different 13C-pocket internal structures to better explain zirconium isotope measurements in mainstream presolar SiC grains by Nicolussi et al. and Barzyk et al. We show that higher-than-solar 92Zr/94Zr ratios can be predicted by adopting a 13C-pocket with a flat 13C profile, instead of the previous decreasing-with-depth 13C profile. The improved agreement between grain data for zirconium isotopes and AGB models provides additional support for a recent proposal of a flat 13C profile based on barium isotopes in mainstream SiC grains by Liu et al.

  6. Hyperpolarized NMR of plant and cancer cell extracts at natural abundance.

    PubMed

    Dumez, Jean-Nicolas; Milani, Jonas; Vuichoud, Basile; Bornet, Aurélien; Lalande-Martin, Julie; Tea, Illa; Yon, Maxime; Maucourt, Mickaël; Deborde, Catherine; Moing, Annick; Frydman, Lucio; Bodenhausen, Geoffrey; Jannin, Sami; Giraudeau, Patrick

    2015-09-01

    Natural abundance (13)C NMR spectra of biological extracts are recorded in a single scan provided that the samples are hyperpolarized by dissolution dynamic nuclear polarization combined with cross polarization. Heteronuclear 2D correlation spectra of hyperpolarized breast cancer cell extracts can also be obtained in a single scan. Hyperpolarized NMR of extracts opens many perspectives for metabolomics. PMID:26215673

  7. Consistent fractionation of 13C in nature and in the laboratory: growth-rate effects in some haptophyte algae.

    PubMed

    Bidigare, R R; Fluegge, A; Freeman, K H; Hanson, K L; Hayes, J M; Hollander, D; Jasper, J P; King, L L; Laws, E A; Milder, J; Millero, F J; Pancost, R; Popp, B N; Steinberg, P A; Wakeham, S G

    1997-06-01

    The carbon isotopic fractionation accompanying formation of biomass by alkenone-producing algae in natural marine environments varies systematically with the concentration of dissolved phosphate. Specifically, if the fractionation is expressed by epsilon p approximately delta e - delta p, where delta e and delta p are the delta 13C values for dissolved CO2 and for algal biomass (determined by isotopic analysis of C37 alkadienones), respectively, and if Ce is the concentration of dissolved CO2, micromole kg-1, then b = 38 + 160*[PO4], where [PO4] is the concentration of dissolved phosphate, microM, and b = (25 - epsilon p)Ce. The correlation found between b and [PO4] is due to effects linking nutrient levels to growth rates and cellular carbon budgets for alkenone-containing algae, most likely by trace-metal limitations on algal growth. The relationship reported here is characteristic of 39 samples (r2 = 0.95) from the Santa Monica Basin (six different times during the annual cycle), the equatorial Pacific (boreal spring and fall cruises as well as during an iron-enrichment experiment), and the Peru upwelling zone. Points representative of samples from the Sargasso Sea ([PO4] < or = 0.1 microM) fall above the b = f[PO4] line. Analysis of correlations expected between mu (growth rate), epsilon p, and Ce shows that, for our entire data set, most variations in epsilon p result from variations in mu rather than Ce. Accordingly, before concentrations of dissolved CO2 can be estimated from isotopic fractionations, some means of accounting for variations in growth rate must be found, perhaps by drawing on relationships between [PO4] and Cd/Ca ratios in shells of planktonic foraminifera. PMID:11540616

  8. Consistent fractionation of 13C in nature and in the laboratory: Growth-rate effects in some haptophyte algae

    NASA Astrophysics Data System (ADS)

    Bidigare, Robert R.; Fluegge, Arnim; Freeman, Katherine H.; Hanson, Kristi L.; Hayes, John M.; Hollander, David; Jasper, John P.; King, Linda L.; Laws, Edward A.; Milder, Jeffrey; Millero, Frank J.; Pancost, Richard; Popp, Brian N.; Steinberg, Paul A.; Wakeham, Stuart G.

    1997-06-01

    The carbon isotopic fractionation accompanying formation of biomass by alkenone-producing algae in natural marine environments varies systematically with the concentration of dissolved phosphate. Specifically, if the fractionation is expressed by єP ≈ δe - δp, where δe and δp are the δ13C values for dissolved CO2 and for algal biomass (determined by isotopic analysis of C37 alkadienones), respectively, and if Ce is the concentration of dissolved CO2, μmol kg-1, then b = 38 + 160*[PO4], where [PO4] is the concentration of dissolved phosphate, μM, and b = (25 - єp)Ce. The correlation found between b and [PO4] is due to effects linking nutrient levels to growth rates and cellular carbon budgets for alkenone-containing algae, most likely by trace-metal limitations on algal growth. The relationship reported here is characteristic of 39 samples (r2 = 0.95) from the Santa Monica Basin (six different times during the annual cycle), the equatorial Pacific (boreal spring and fall cruises as well as during an iron-enrichment experiment), and the Peru upwelling zone. Points representative of samples from the Sargasso Sea ([PO4] ≤ 0.1 μM) fall above the b = f[PO4] line. Analysis of correlations expected between μ (growth rate), єp, and Ce shows that, for our entire data set, most variations in єp result from variations in μ rather than Ce. Accordingly, before concentrations of dissolved CO2 can be estimated from isotopic fractionations, some means of accounting for variations in growth rate must be found, perhaps by drawing on relationships between [PO4] and Cd/Ca ratios in shells of planktonic foraminifera.

  9. The effect of dietary amino acid abundance and isotopic composition on the growth rate, metabolism and tissue δ13C of rainbow trout.

    PubMed

    Gaye-Siessegger, Julia; McCullagh, James S O; Focken, Ulfert

    2011-06-28

    The aim of the present study was to test whether the dietary non-essential/conditionally essential amino acid composition has an effect on growth and protein utilisation and on δ13C of individual amino acids in rainbow trout (Oncorhynchus mykiss). Trout were reared on six purified diets containing only synthetic amino acids in place of protein. Diet 1 mimicked the amino acid composition of fishmeal, in diet 2, cysteine (Cys), glycine (Gly), proline (Pro) and tyrosine (Tyr) were isonitrogenously replaced by their precursor amino acids serine (Ser), glutamic acid (Glu) and phenylalanine (Phe), and in diet 3, alanine (Ala), asparagine and aspartate, Cys, Gly, Pro, Ser and Tyr were isonitrogenously replaced by Glu. Diets 4, 5 and 6 resembled diets 1, 2 and 3 except that Glu contained 0·1 % 13C-enriched Glu. A control group was reared on a fishmeal-based diet. A total of forty-two trout (4·7 (sd 0·57) g) were fed one of the diets at a level of 3·5 % body mass for 10 weeks in a flow-through system. Dietary non-essential amino acid composition significantly influenced protein gain (P < 0·025) and δ13C of Ala, arginine (Arg), Gly, histidine (His), Phe and Tyr. Non-enriched Glu was predominantly found in trout fed 13C-enriched Glu, which is consistent with the fact that Glu has been shown to be used extensively in the gut as an energy source but is less consistent with the enrichment of Pro in fish fed diet 6 compared with fish fed diet 3. Further research is required to better understand the mechanisms that lead to the alteration of amino acid δ13C between diet and body tissues. PMID:21418707

  10. Distinct fungal and bacterial δ13C signatures can drive the increase in soil δ13C with depth

    NASA Astrophysics Data System (ADS)

    Kohl, Lukas; Laganièrea, Jérôme; Edwards, Kate A.; Billings, Sharon A.; Morrill, Penny L.; Van Biesen, Geert; Ziegler, Susan E.

    2015-04-01

    Soil microbial biomass is a key precursor of soil organic carbon (SOC), and the enrichment in 13C during SOC diagenesis has been purported to be driven by increasing proportions of microbially derived SOC. Yet, little is known about how the δ13C of soil microbial biomass - and by extension the δ13C of microbial inputs to SOC - vary in space, time, or with the composition of the microbial community. Phospholipid fatty acids (PLFA) can be analyzed to measure the variation of the natural abundance δ13C values of both individual groups of microorganisms and the microbial community as a whole. Here, we show how variations of δ13CPLFA within the soil profile provides insight into C fluxes in undisturbed soils and demonstrate that distinct δ13C of fungal and bacterial biomass and their relative abundance can drive the increase of bulk δ13CSOC with depth. We studied the variation in natural abundance δ13C signatures of PLFA in podzolic soil profiles from mesic boreal forests in Atlantic Canada. Samples from the organic horizons (L,F,H) and the mineral (B; top 10 cm) horizons were analyzed for δ13C values of PLFA specific to fungi, G+ bacteria, or G- bacteria as proxies for the δ13C of the biomass of these groups, and for δ13C values of PLFA produced by a wide range of microorganisms (e.g. 16:0) as a proxy for the δ13C value of microbial biomass as a whole. Results were compared to fungi:bacteria ratios (F:B) and bulk δ13CSOC values. The δ13C values of group-specific PLFA were driven by differences among source organisms, with fungal PLFA consistently depleted (2.1 to 6.4‰) relative to and G+ and G- bacterial PLFA in the same sample. All group-specific PLFA, however, exhibited nearly constant δ13C values throughout the soil profile, apparently unaffected by the over 2.8‰ increase in δ13CSOC with depth from the L to B horizons. This indicates that bulk SOC poorly represents the substrates actually consumed by soil microorganisms in situ. Instead, our

  11. Application of (13)C ramp CPMAS NMR with phase-adjusted spinning sidebands (PASS) for the quantitative estimation of carbon functional groups in natural organic matter.

    PubMed

    Ikeya, Kosuke; Watanabe, Akira

    2016-01-01

    The composition of carbon (C) functional groups in natural organic matter (NOM), such as dissolved organic matter, soil organic matter, and humic substances, is frequently estimated using solid-state (13)C NMR techniques. A problem associated with quantitative analysis using general cross polarization/magic angle spinning (CPMAS) spectra is the appearance of spinning side bands (SSBs) split from the original center peaks of sp (2) hybridized C species (i.e., aromatic and carbonyl C). Ramp CP/phase-adjusted side band suppressing (PASS) is a pulse sequence that integrates SSBs separately and quantitatively recovers them into their inherent center peaks. In the present study, the applicability of ramp CP/PASS to NOM analysis was compared with direct polarization (DPMAS), another quantitative method but one that requires a long operation time, and/or a ramp CP/total suppression side band (ramp CP/TOSS) technique, a popular but non-quantitative method for deleting SSBs. The test materials were six soil humic acid samples with various known degrees of aromaticity and two fulvic acids. There were no significant differences in the relative abundance of alkyl C, O-alkyl C, and aromatic C between the ramp CP/PASS and DPMAS methods, while the signal intensities corresponding to aromatic C in the ramp CP/TOSS spectra were consistently less than the values obtained in the ramp CP/PASS spectra. These results indicate that ramp CP/PASS can be used to accurately estimate the C composition of NOM samples. PMID:26522329

  12. Helium isotopic abundance variation in nature

    SciTech Connect

    Holden, N.E.

    1993-08-01

    The isotopic abundance of helium in nature has been reviewed. This atomic weight value is based on the value of helium in the atmosphere, which is invariant around the world and up to a distance of 100,000 feet. Helium does vary in natural gas, volcanic rocks and gases, ocean floor sediments, waters of various types and in radioactive minerals and ores due to {alpha} particle decay of radioactive nuclides.

  13. Nicotine, acetanilide and urea multi-level 2H-, 13C- and 15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry.

    PubMed

    Schimmelmann, Arndt; Albertino, Andrea; Sauer, Peter E; Qi, Haiping; Molinie, Roland; Mesnard, François

    2009-11-01

    Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the delta values of these reference materials should bracket the isotopic range of samples with unknown delta values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for delta13C and delta15N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: delta2H(nicotine) -162 to -45 per thousand, delta13C(nicotine) -30.05 to +7.72 per thousand, delta15N(nicotine) -6.03 to +33.62 per thousand; delta15N(acetanilide) +1.18 to +40.57 per thousand; delta13C(urea) -34.13 to +11.71 per thousand, delta15N(urea) +0.26 to +40.61 per thousand (recommended delta values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as

  14. Will Abundant Natural Gas Solve Climate Change?

    NASA Astrophysics Data System (ADS)

    McJeon, H. C.; Edmonds, J.; Bauer, N.; Leon, C.; Fisher, B.; Flannery, B.; Hilaire, J.; Krey, V.; Marangoni, G.; Mi, R.; Riahi, K.; Rogner, H.; Tavoni, M.

    2015-12-01

    The rapid deployment of hydraulic fracturing and horizontal drilling technologies enabled the production of previously uneconomic shale gas resources in North America. Global deployment of these advanced gas production technologies could bring large influx of economically competitive unconventional gas resources to the energy system. It has been hoped that abundant natural gas substituting for coal could reduce carbon dioxide (CO2) emissions, which in turn could reduce climate forcing. Other researchers countered that the non-CO2 greenhouse gas (GHG) emissions associated with shale gas production make its lifecycle emissions higher than those of coal. In this study, we employ five state-of-the-art integrated assessment models (IAMs) of energy-economy-climate systems to assess the full impact of abundant gas on climate change. The models show large additional natural gas consumption up to +170% by 2050. The impact on CO2 emissions, however, is found to be much smaller (from -2% to +11%), and a majority of the models reported a small increase in climate forcing (from -0.3% to +7%) associated with the increased use of abundant gas. Our results show that while globally abundant gas may substantially change the future energy market equilibrium, it will not significantly mitigate climate change on its own in the absence of climate policies.

  15. A Study of the Abundance and 13C/12C Ratio of Atmospheric Carbon Dioxide to Advance the Scientific Understanding of Terrestrial Processes Regulating the Global Carbon Cycle

    SciTech Connect

    Stephen C. Piper

    2005-10-15

    The primary goal of our research program, consistent with the goals of the U.S. Climate Change Science Program and funded by the terrestrial carbon processes (TCP) program of DOE, has been to improve understanding of changes in the distribution and cycling of carbon among the active land, ocean and atmosphere reservoirs, with particular emphasis on terrestrial ecosystems. Our approach is to systematically measure atmospheric CO2 to produce time series data essential to reveal temporal and spatial patterns. Additional measurements of the 13C/12C isotopic ratio of CO2 provide a basis for distinguishing organic and inorganic processes. To pursue the significance of these patterns further, our research also involved interpretations of the observations by models, measurements of inorganic carbon in sea water, and of CO2 in air near growing land plants.

  16. Strategy for Enhancement of (13)C-Photo-CIDNP NMR Spectra by Exploiting Fractional (13)C-Labeling of Tryptophan.

    PubMed

    Eisenreich, Wolfgang; Joshi, Monika; Illarionov, Boris; Kacprzak, Sylwia; Lukaschek, Michail; Kothe, Gerd; Budisa, Nediljko; Fischer, Markus; Bacher, Adelbert; Weber, Stefan

    2015-10-29

    The photo-CIDNP effect has proven to be useful to strongly enhance NMR signals of photochemically active proteins simply by irradiation with light. The evolving characteristic patterns of enhanced absorptive and emissive NMR lines can be exploited to elucidate the photochemistry and photophysics of light-driven protein reactions. In particular, by the assignment of (13)C NMR resonances, redox-active amino acids may be identified and thereby electron-transfer pathways unraveled, in favorable cases, even with (13)C at natural abundance. If signal enhancement is weak, uniform (13)C isotope labeling is traditionally applied to increase the signal strength of protein (13)C NMR. However, this typically leads to cross relaxation, which transfers light-induced nuclear-spin polarization to adjacent (13)C nuclei, thereby preventing an unambiguous analysis of the photo-CIDNP effect. In this contribution, two isotope labeling strategies are presented; one leads to specific but ubiquitous (13)C labeling in tryptophan, and the other is based on fractional isotope labeling affording sets of isotopologs with low probability of next-neighbor isotope accumulation within individual tryptophan molecules. Consequently, cross relaxation is largely avoided while the signal enhancement by (13)C enrichment is preserved. This results in significantly simplified polarization patterns that are easier to analyze with respect to the generation of light-generated nuclear-spin polarization. PMID:26244593

  17. Nicotine, acetanilide and urea multi-level2H-,13C- and15N-abundance reference materials for continuous-flow isotope ratio mass spectrometry

    USGS Publications Warehouse

    Schimmelmann, A.; Albertino, A.; Sauer, P.E.; Qi, H.; Molinie, R.; Mesnard, F.

    2009-01-01

    Accurate determinations of stable isotope ratios require a calibration using at least two reference materials with different isotopic compositions to anchor the isotopic scale and compensate for differences in machine slope. Ideally, the S values of these reference materials should bracket the isotopic range of samples with unknown S values. While the practice of analyzing two isotopically distinct reference materials is common for water (VSMOW-SLAP) and carbonates (NBS 19 and L-SVEC), the lack of widely available organic reference materials with distinct isotopic composition has hindered the practice when analyzing organic materials by elemental analysis/isotope ratio mass spectrometry (EA-IRMS). At present only L-glutamic acids USGS40 and USGS41 satisfy these requirements for ??13C and ??13N, with the limitation that L-glutamic acid is not suitable for analysis by gas chromatography (GC). We describe the development and quality testing of (i) four nicotine laboratory reference materials for on-line (i.e. continuous flow) hydrogen reductive gas chromatography-isotope ratio mass-spectrometry (GC-IRMS), (ii) five nicotines for oxidative C, N gas chromatography-combustion-isotope ratio mass-spectrometry (GC-C-IRMS, or GC-IRMS), and (iii) also three acetanilide and three urea reference materials for on-line oxidative EA-IRMS for C and N. Isotopic off-line calibration against international stable isotope measurement standards at Indiana University adhered to the 'principle of identical treatment'. The new reference materials cover the following isotopic ranges: ??2Hnicotine -162 to -45%o, ??13Cnicotine -30.05 to +7.72%, ?? 15Nnicotine -6.03 to +33.62%; ??15N acetanilide +1-18 to +40.57%; ??13Curea -34.13 to +11.71%, ??15Nurea +0.26 to +40.61% (recommended ?? values refer to calibration with NBS 19, L-SVEC, IAEA-N-1, and IAEA-N-2). Nicotines fill a gap as the first organic nitrogen stable isotope reference materials for GC-IRMS that are available with different ??13N

  18. Speleothem calcite farmed in situ: Modern calibration of δ 18O and δ 13C paleoclimate proxies in a continuously-monitored natural cave system

    NASA Astrophysics Data System (ADS)

    Tremaine, Darrel M.; Froelich, Philip N.; Wang, Yang

    2011-09-01

    Understanding the relationships between speleothem stable isotopes (δ 13C δ 18O) and in situ cave forcing mechanisms is important to interpreting ancient stalagmite paleoclimate records. Cave studies have demonstrated that the δ 18O of inorganically precipitated (low temperature) speleothem calcite is systematically heavier than the δ 18O of laboratory-grown calcite for a given temperature. To understand this apparent offset, rainwater, cave drip water, groundwater, and modern naturally precipitated calcite (farmed in situ) were grown at multiple locations inside Hollow Ridge Cave in Marianna, Florida. High resolution micrometeorological, air chemistry time series and ventilation regimes were also monitored continuously at two locations inside the cave, supplemented with periodic bi-monthly air gas grab sample transects throughout the cave. Cave air chemistry and isotope monitoring reveal density-driven airflow pathways through Hollow Ridge Cave at velocities of up to 1.2 m s -1 in winter and 0.4 m s -1 in summer. Hollow Ridge Cave displays a strong ventilation gradient in the front of the cave near the entrances, resulting in cave air that is a mixture of soil gas and atmospheric CO 2. A clear relationship is found between calcite δ 13C and cave air ventilation rates estimated by proxies pCO 2 and 222Rn. Calcite δ 13C decreased linearly with distance from the front entrance to the interior of the cave during all seasons, with a maximum entrance-to-interior gradient of Δδ 13C CaCO3 = -7‰. A whole-cave "Hendy test" at multiple contemporaneous farming sites reveals that ventilation induces a +1.9 ± 0.96‰ δ 13C offset between calcite precipitated in a ventilation flow path and calcite precipitated on the edge or out of flow paths. This interpretation of the "Hendy test" has implications for interpreting δ 13C records in ancient speleothems. Calcite δ 13C CaCO3 may be a proxy not only for atmospheric CO 2 or overlying vegetation shifts but also for

  19. Whole-core analysis by sup 13 C NMR

    SciTech Connect

    Vinegar, H.J.; Tutunjian, P.N. ); Edelstein, W.A.; Roemer, P.B. )

    1991-06-01

    This paper reports on a whole-core nuclear magnetic resonance (NMR) system that was used to obtain natural abundance {sup 13}C spectra. The system enables rapid, nondestructive measurements of bulk volume of movable oil, aliphatic/aromatic ratio, oil viscosity, and organic vs. carbonate carbon. {sup 13}C NMR can be used in cores where the {sup 1}H NMR spectrum is too broad to resolve oil and water resonances separately. A 5 1/4-in. {sup 13}C/{sup 1}H NMR coil was installed on a General Electric (GE) CSI-2T NMR imager/spectrometer. With a 4-in.-OD whole core, good {sup 13}C signal/noise ratio (SNR) is obtained within minutes, while {sup 1}H spectra are obtained in seconds. NMR measurements have been made of the {sup 13}C and {sup 1}H density of crude oils with a wide range of API gravities. For light- and medium-gravity oils, the {sup 13}C and {sup 1}H signal per unit volume is constant within about 3.5%. For heavy crudes, the {sup 13}C and {sup 1}H density measured by NMR is reduced by the shortening of spin-spin relaxation time. {sup 13}C and {sup 1}H NMR spin-lattice relaxation times were measured on a suite of Cannon viscosity standards, crude oils (4 to 60{degrees} API), and alkanes (C{sub 5} through C{sub 16}) with viscosities at 77{degrees}F ranging from 0.5 cp to 2.5 {times} 10{sup 7} cp. The {sup 13}C and {sup 1}H relaxation times show a similar correlation with viscosity from which oil viscosity can be estimated accurately for viscosities up to 100 cp. The {sup 13}C surface relaxation rate for oils on water-wet rocks is very low. Nonproton decoupled {sup 13}C NMR is shown to be insensitive to kerogen; thus, {sup 13}C NMR measures only the movable hydrocarbon content of the cores. In carbonates, the {sup 13}C spectrum also contains a carbonate powder pattern useful in quantifying inorganic carbon and distinguishing organic from carbonate carbon.

  20. Determining the Local Abundance of Martian Methane and its 13-C/l2-C and D/H Isotopic Ratios for Comparison with Related Gas and Soil Analysis on the 2011 Mars Science Laboratory (MSL) Mission

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R.; Mahaffy, Paul R.

    2011-01-01

    Understanding the origin of Martian methane will require numerous complementary measurements from both in situ and remote sensing investigations and laboratory work to correlate planetary surface geophysics with atmospheric dynamics and chemistry. Three instruments (Quadrupole Mass Spectrometer (QMS), Gas Chromatograph (GC) and Tunable Laser Spectrometer (TLS)) with sophisticated sample handling and processing capability make up the Sample Analysis at Mars (SAM) analytical chemistry suite on NASA s 2011 Mars Science Laboratory (MSL) Mission. Leveraging off the SAM sample and gas processing capability that includes methane enrichment, TLS has unprecedented sensitivity for measuring absolute methane (parts-per-trillion), water, and carbon dioxide abundances in both the Martian atmosphere and evolved from heated soil samples. In concert with a wide variety of associated trace gases (e.g. SO2, H2S, NH3, higher hydrocarbons, organics, etc.) and other isotope ratios measured by SAM, TLS will focus on determining the absolute abundances of methane, water and carbon dioxide, and their isotope ratios: 13C/12C and D/H in methane; 13C/12C and 18O/17O/16O in carbon dioxide; and 18O/17O/16O and D/H in water. Measurements near the MSL landing site will be correlated with satellite (Mars Express, Mars 2016) and ground-based observations.

  1. Late-Quaternary variation in C3 and C4 grass abundance in southeastern Australia as inferred from δ13C analysis: Assessing the roles of climate, pCO2, and fire

    NASA Astrophysics Data System (ADS)

    Nelson, David M.; Urban, Michael A.; Kershaw, A. Peter; Hu, Feng Sheng

    2016-05-01

    Climate, atmospheric pCO2, and fire all may exert major influences on the relative abundance of C3 and C4 grasses in the present-day vegetation. However, the relative role of these factors in driving variation in C3 and C4 grass abundances in the paleorecord is uncertain, and C4 abundance is often interpreted narrowly as a proxy indicator of aridity or pCO2. We measured δ13C values of individual grains of grass (Poaceae) pollen in the sediments of two sites in southeastern Australia to assess changes in the proportions of C3 and C4 grasses during the past 25,000 years. These data were compared with shifts in pCO2, temperature, moisture balance, and fire to assess how these factors were related to long-term variation of C4 grass abundance during the late Quaternary. At Caledonia Fen, a high-elevation site in the Snowy Mountains, C4 grass abundance decreased from an average of 66% during the glacial period to 11% during the Holocene, primarily in response to increased pCO2 and temperature. In contrast, this pattern did not exist in low-elevation savannah woodlands around Tower Hill Northwest Crater, where C4 grass abundance instead varied in response to shifts in regional aridity. Fire did not appear to have strongly influenced the proportions of C3 and C4 grasses on the landscape at millennial timescales at either site. These patterns are similar to those of a recent study in East Africa, suggesting that elevation-related climatic differences influence how the abundance of C3 and C4 grasses responds to shifts in climate and pCO2. These results caution against using C4 plant abundance as a proxy indicator of either climate or pCO2 without an adequate understanding of key controlling factors.

  2. Study of molecular interactions with 13C DNP-NMR

    NASA Astrophysics Data System (ADS)

    Lerche, Mathilde H.; Meier, Sebastian; Jensen, Pernille R.; Baumann, Herbert; Petersen, Bent O.; Karlsson, Magnus; Duus, Jens Ø.; Ardenkjær-Larsen, Jan H.

    2010-03-01

    NMR spectroscopy is an established, versatile technique for the detection of molecular interactions, even when these interactions are weak. Signal enhancement by several orders of magnitude through dynamic nuclear polarization alleviates several practical limitations of NMR-based interaction studies. This enhanced non-equilibrium polarization contributes sensitivity for the detection of molecular interactions in a single NMR transient. We show that direct 13C NMR ligand binding studies at natural isotopic abundance of 13C gets feasible in this way. Resultant screens are easy to interpret and can be performed at 13C concentrations below μM. In addition to such ligand-detected studies of molecular interaction, ligand binding can be assessed and quantified with enzymatic assays that employ hyperpolarized substrates at varying enzyme inhibitor concentrations. The physical labeling of nuclear spins by hyperpolarization thus provides the opportunity to devise fast novel in vitro experiments with low material requirement and without the need for synthetic modifications of target or ligands.

  3. Use of 13C NMR and ftir for elucidation of degradation pathways during natural litter decomposition and composting I. early stage leaf degradation

    USGS Publications Warehouse

    Wershaw, R. L.; Leenheer, J.A.; Kennedy, K.R.; Noyes, T.I.

    1996-01-01

    Oxidative degradation of plant tissue leads to the formation of natural dissolved organic carbon (DOC) and humus. Infrared (IR) and 13C nuclear magnetic resonance (NMR) spectrometry have been used to elucidate the chemical reactions of the early stages of degradation that give rise to DOC derived from litter and compost. The results of this study indicate that oxidation of the lignin components of plant tissue follows the sequence of O-demethylation, and hydroxylation followed by ring-fission, chain-shortening, and oxidative removal of substituents. Oxidative ring-fission leads to the formation of carboxylic acid groups on the cleaved ends of the rings and, in the process, transforms phenolic groups into aliphatic alcoholic groups. The carbohydrate components are broken down into aliphatic hydroxy acids and aliphatic alcohols.

  4. Long-term Trends and Confidence in Global Natural Gas Fugitive Emissions Rates Based on δ13C-CH4

    NASA Astrophysics Data System (ADS)

    Schwietzke, S.; Sherwood, O.; Tans, P. P.; Michel, S. E.; Miller, J. B.; Dlugokencky, E. J.; Griffin, W. M.; Bruhwiler, L.

    2014-12-01

    Numerous life cycle assessment (LCA) and field studies have estimated natural gas (NG) fugitive emissions rates (FER) - the fraction of produced NG, mostly CH4, emitted to the atmosphere, unintentionally or by design, during extraction, processing, transport, and distribution - at local, regional, and national scales. In a recent study, we estimated for the first time the global mean FER using long-term (three decades) atmospheric CH4, δ13C-CH4, and C2H6 measurements from global monitoring networks. As a further development, this work investigates the global mean FER uncertainty range (factor of 2) in more detail to increase confidence in the results. The objectives of this research are to (i) estimate probability distribution functions (PDF) of global mean FER, and (ii) identify long-term trends in global fossil fuel (FF) and other CH4 sources. In order to achieve these objectives, global atmospheric δ13C-CH4 measurements since the mid-1980s are analyzed using a box-model of the global CH4 sources and sinks. First, we derive PDFs of the key model parameters including literature isotopic source signatures, atmospheric lifetimes, natural and anthropogenic emissions, and FF hydrocarbon gas composition. Second, a Monte Carlo simulation of the box-model is performed to quantify FER confidence intervals. While our model attributes the majority of increased CH4 levels over the past three decades to microbial sources, FF sources have also increased slightly. However, FER - an indicator of NG life cycle efficiency - has decreased over the same period given the large NG production increase worldwide. Results are most sensitive to global average microbial isotopic signatures (weighted by source strength) and bottom-up estimates of biomass burning emissions, which will be discussed in more detail.

  5. Structural determination of complex natural products by quantum mechanical calculations of (13)C NMR chemical shifts: development of a parameterized protocol for terpenes.

    PubMed

    de Albuquerque, Ana Carolina Ferreira; Ribeiro, Daniel Joras; de Amorim, Mauro Barbosa

    2016-08-01

    Nuclear magnetic resonance (NMR) spectroscopy is one of the most important tools for determining the structures of organic molecules. Despite the advances made in this technique, revisions of erroneously established structures for natural products are still commonly published in the literature. In this context, the prediction of chemical shifts through ab initio and density functional theory (DFT) calculations has become a very powerful tool for assisting with the structural determination of complex organic molecules. In this work, we present the development of a protocol for (13)C chemical shift calculations of terpenes, a class of natural products that are widely distributed among plant species and are very important due to their biological and pharmacological activities. This protocol consists of GIAO-DFT calculations of chemical shifts and the application of a parameterized scaling factor in order to ensure accurate structural determination of this class of natural products. The application of this protocol to a set of five terpenes yielded accurate calculated chemical shifts, showing that this is a very attractive tool for the calculation of complex organic structures such as terpenes. PMID:27424297

  6. A study of the abundance and {sup 13}C/{sup 12}C ratio of atmospheric carbon dioxide and oceanic carbon in relation to the global carbon cycle. Final technical report, February 15, 1990--July 31, 1995

    SciTech Connect

    Keeling, C.D.

    1995-12-31

    Knowledge can be gained about the fluxes and storage of carbon in natural systems and their relation to climate by detecting temporal and spatial patterns in atmospheric CO{sub 2}. When patterns in its {sup 13}C/{sup 12}C isotopic ratio are included in the analysis, there is also a basis for distinguishing organic and inorganic processes. The authors systematically measured the concentration and {sup 13}C/{sup 12}C ratio of atmospheric CO{sub 2} to produce time series data essential to reveal these temporal and spatial patterns. To pursue the significance of these patterns further, the result also involved measurements of inorganic carbon in sea water and of CO{sub 2} in air near growing land plants. The study was coordinated with a study of the same title concurrently funded by the National Science Foundation (NSF). The study called for continued atmospheric measurements at an array of ten stations from the Arctic Basin to the South Pole. Air was collected in flasks brought back to the laboratory for analysis, except at Mauna Loa. Observatory, Hawaii, where continuous measurements were also carried out.

  7. Crystal structure and theoretical study of IR and 1H and 13C NMR spectra of cordatin, a natural product with antiulcerogenic activity

    NASA Astrophysics Data System (ADS)

    Brasil, Davi S. B.; Alves, Cláudio N.; Guilhon, Giselle M. S. P.; Muller, Adolfo H.; Secco, Ricardo De S.; Peris, Gabriel; Llusar, Rosa

    Cordatin is a furan diterpenoid with a clerodane skeleton isolated from Croton palanostigma Klotzsch (Euphorbiaceae). This natural product shows significant antiulcerogenic activity, similar to cimetidine (Tagamet®), a compound used for the treatment of peptic ulcers. The crystal structure of cordatin was obtained by X-ray diffraction and its geometrical parameters were compared with theoretical calculations at the B3LYP theory level. The IR and NMR (1H and 13C chemical shifts and coupling constants) spectra were obtained and compared with the theoretical calculations. The B3LYP theory level, with the 6-31G(d,p) and 6-311G(d,p) basis set, provided IR absorption values close to the experimental data. Moreover, theoretical NMR parameters obtained in both gas phase and chloroform solvent at the B3PW91/DGDZVP, B3LYP/6-311+G(2d,p), and B3PW91/6-311+G(2d,p) levels showed good correlations with the experimental results.

  8. 13C/12C and 15N/14N Isotope Analysis to Characterize Natural Degradation of Atrazine: Evidence from Parent and Daughter Compound Values

    NASA Astrophysics Data System (ADS)

    Elsner, Martin; Meyer, Armin

    2013-04-01

    The mobile and still herbicidal metabolites desethylatrazine (DEA) and desisopropylatrazine (DIA) are frequently detected together with its parent compound atrazine (Atz) in the aquatic environment. Interpretation of their transformation state is often difficult with current methods, which are mainly measuring concentrations. Alternatively, compound specific isotope analyses (CSIA) has become a novel tool to detect degradation processes of contaminants in groundwater. The aim of our study was to investigate on the lab scale 13C/12C and 15N/14N isotope trends in parent and daughter compounds associated with different degradation scenarios of atrazine likely to occur in the environment. Thus atrazine was dealkylated with (i) permanganate and (ii) the bacterium Rhodococcus sp. NI86/21. In both transformations, 13C/12C ratios of atrazine increased strongly (epsilon carbon/permanganate = -4.6 ± 0.6 ‰ and epsilon carbon/Rhodoccoccus = -3.8 ± 0.2 ‰) whereas nitrogen isotope fractionation was small. 13C/12C ratios of DEA showed the following trends. (i) When DEA was formed as only product (Atz + permanganate) 13C/12C remained constant, close to the initial value of Atz. (ii) When DEA was formed together with deisopropylatrazine (biodegradation of Atz) 13C/12C increased, but only within 2‰. (iii) When DEA and DIA was further biodegraded, 13C/12C increased for both metabolites up to 9‰. Thus strong enrichment of 13C/12C in the metabolites in comparison to Atz can give strong testimony for further breakdown of the metabolite.

  9. In Situ 13C and 23Na Magic Angle Spinning NMR Investigation of Supercritical CO2 Incorporation in Smectite-Natural Organic Matter Composites

    SciTech Connect

    Bowers, Geoffrey M.; Hoyt, David W.; Burton, Sarah D.; Ferguson, Brennan O.; Varga, Tamas; Kirkpatrick, Robert J.

    2014-01-29

    This paper presents an in situ NMR study of clay-natural organic polymer systems (a hectoritehumic acid [HA] composite) under CO2 storage reservoir conditions (90 bars CO2 pressure, 50°C). The 13C and 23Na NMR data show that supercritical CO2 interacts more strongly with the composite than with the base clay and does not react to form other C-containing species over several days at elevated CO2. With and without organic matter, the data suggest that CO2 enters the interlayer space of Na-hectorite equilibrated at 43% relative humidity. The presence of supercritical CO2 also leads to increased 23Na signal intensity, reduced line width at half height, increased basal width, more rapid 23Na T1 relaxation rates, and a shift to more positive resonance frequencies. Larger changes are observed for the hectorite-HA composite than for the base clay. In light of recently reported MD simulations of other polymer-Na-smectite composites, we interpret the observed changes as an increase in the rate of Na+ site hopping in the presence of supercritical CO2, the presence of potential new Na+ sorption sites when the humic acid is present, and perhaps an accompanying increase in the number of Na+ ions actively involved in site hopping. The results suggest that the presence of organic material either in clay interlayers or on external particle surfaces can significantly affect the behavior of supercritical CO2 and the mobility of metal ions in reservoir rocks.

  10. Development of a 13C-optimized 1.5-mm high temperature superconducting NMR probe

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Vijaykumar; Hooker, Jerris W.; Withers, Richard S.; Nast, Robert E.; Brey, William W.; Edison, Arthur S.

    2013-10-01

    We report a 1.5-mm NMR probe based on high temperature superconductors operating at 14.1 T optimized for 13C detection. The probe has a total sample volume of about 35 microliters (μL) with an active volume of 20 μL and provides exceptional mass sensitivity for 13C detection. The probe also has excellent 1H sensitivity and employs a 2H lock; 15N irradiation capability can be added in the future. The coils are cooled to about 20 K using a standard Agilent cryogenic refrigeration system, and the sample temperature is regulated near room temperature. The coil design considerations are discussed in detail. This probe is ideal for directly detected 13C NMR experiments for natural products chemistry and metabolomics applications, for which 35 μL is an optimal sample volume. The outstanding 13C sensitivity of this probe allowed us to directly determine the 13C connectivity on 1.1 mg of natural abundance histidine using an INADEQUATE experiment. We demonstrated the utility of this probe for 13C-based metabolomics using a synthetic mixture of common natural abundance metabolites whose concentrations ranged from 1 to 5 mM (40-200 nmol).

  11. Development of a 13C-Optimized 1.5-mm High Temperature Superconducting NMR Probe

    PubMed Central

    Ramaswamy, Vijaykumar; Hooker, Jerris W.; Withers, Richard S.; Nast, Robert E.; Brey, William W.; Edison, Arthur S.

    2013-01-01

    We report a 1.5-mm NMR probe based on high temperature superconductors operating at 14.1 T optimized for 13C detection. The probe has a total sample volume of about 35 microliters (μL) with an active volume of 20 μL and provides exceptional mass sensitivity for 13C detection. The probe also has excellent 1H sensitivity and employs a 2H channel lock; 15N irradiation capability can be added in the future. The coils are cooled to about 20 K using a standard Agilent cryogenic refrigeration system, and the sample temperature is regulated near room temperature. The coil design considerations are discussed in detail. This probe is ideal for directly detected 13C NMR experiments for natural products chemistry and metabolomics applications, for which 35 μL is an optimal sample volume. The outstanding 13C sensitivity of this probe allowed us to directly determine the 13C connectivity on 1.1 mg of natural abundance histidine using an INADEQUATE experiment. We demonstrated the utility of this probe for 13C-based metabolomics using a synthetic mixture of common natural abundance metabolites whose concentrations ranged from 1 to 5 mM (40 to 200 nmol). PMID:23969086

  12. Measuring doubly 13C-substituted ethane by mass spectrometry

    NASA Astrophysics Data System (ADS)

    Clog, M.; Ling, C.; Eiler, J. M.

    2012-12-01

    Ethane (C2H6) is present in non-negligible amounts in most natural gas reservoirs and is used to produce ethylene for petrochemical industries. It is one of the by-products of lipid metabolism and is the arguably simplest molecule that can manifest multiple 13C substitutions. There are several plausible controls on the relative abundances of 13C2H6 in natural gases: thermodynamically controlled homogeneous isotope exchange reactions analogous to those behind carbonate clumped isotope thermometry; inheritance from larger biomolecules that under thermal degradation to produce natural gas; mixing of natural gases that differ markedly in bulk isotopic composition; or combinations of these and/or other, less expected fractionations. There is little basis for predicting which of these will dominate in natural samples. Here, we focus on an analytical techniques that will provide the avenue for exploring these phenomena. The method is based on high-resolution gas source isotope ratio mass spectrometry, using the Thermo 253-Ultra (a new prototype mass spectrometer). This instrument achieves the mass resolution (M/Δ M) up to 27,000, permitting separation of the isobaric interferences of potential contaminants and isotopologues of an analtye or its fragments which share a cardinal mass. We present techniques to analyze several isotopologues of molecular and fragment ions of C2H6. The critical isobaric separations for our purposes include: discrimination of 13C2H6 from 13C12CDH5 at mass 32 and separation of the 13CH3 fragment from 12CH4 at mass 16, both requiring at least a mass resolution of 20000 to make an adequate measurement. Other obvious interferences are either cleanly separated (e.g., O2, O) or accounted for by peak-stripping (CH3OH on mass 32 and NH2 on mass 16). We focus on a set of measurements which constrain: the doubly-substituted isotopologue, 13C2H6, and the 13CH3/12CH3 ratio of the methyl fragment, which constrains the bulk δ 13C. Similar methods can be

  13. Investigating microbial carbon cycling using natural abundance isotope analysis of PLFA

    NASA Astrophysics Data System (ADS)

    Slater, G. G.; Brady, A.; Cowie, B.

    2008-12-01

    Understanding microbial carbon sources and cycling is fundamental to our conceptualization of microbial ecosystems and their role in biogeochemical cycling in natural systems. Achieving this understanding requires application of a wide range of approaches. Natural abundance isotope analysis of individual compounds, particularly cellular components such as Phospholipids Fatty Acids (PLFA) can provide insights into the carbon sources and metabolic activities of the in situ microbial community from environmental samples. This is primarily because specific PLFA can be well resolved by gas chromatography even from complex matrices where confounding biological/organic compound abound. These PLFA can then be attributed to the viable microbial community, in some cases to specific components of this community and due to characteristic biosynthetic fractionations of stable isotope ratios, δ13C analysis of PLFA can: differentiate isotopically distinct primary carbon sources of heterotrophic communities; identify isotopic patterns characteristic of autotrophic versus heterotrophic processes; and elucidate microbial biosynthetic pathways. In cases where there δ13C cannot provide resolution of carbon sources, new approaches in Δ14C of PLFA can be applied. The vast range in Δ14C of ancient and modern carbon provides an easily traceable signal that can differentiate uptake and utilization of these carbon sources. This is particularly useful in cases such as contaminated sites where petroleum based contamination has occurred, or in natural systems where microbial communities may be utilizing geologic versus recently photosynthetically fixed carbon. This talk will present several examples demonstrating the utility of this approach.

  14. 13C FRACTIONATION DURING RELIC SOIL ORGANIC C MINERALIZATION ON CARBON BUDGETS AND HALF-LIVES CALCULATED USING THE STABLE ISOTOPE APPROACH

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The 13C natural abundance approach for determining soil organic C (SOC) stability and turnover has been used to determine SOC mineralization kinetics. These calculations often assume that 13C fractionation during relic SOC and non-harvested biomass mineralization is insignificant. The objective of t...

  15. Constraints on the factors controlling 13C-18O bond abundances in biologically precipitated carbonates from measurements of marine calcifiers cultured at variable temperature, pH, and salinity

    NASA Astrophysics Data System (ADS)

    Conchas, T. E.; Eagle, R.; Eiler, J. M.; Ries, J. B.; Freitas, P. S.; Hiebenthal, C.; Wanamaker, A. D.; Tripati, A. K.

    2012-12-01

    Marine mollusks and corals are widely used as archives of past climate change; oxygen isotopic composition (δ18O value) of their carbonate minerals is perhaps the most commonly used proxy to reconstruct paleoclimate from these marine calcifiers. However, oxygen isotope paleothermometry of mollusks and corals is complicated by non-equilibrium "vital effects" and variations in seawater pH changes, both of which influence the net fractionation of oxygen isotopes between carbonate and water. Carbonate "clumped isotope" thermometry is an emerging approach that potentially addresses these ambiguities. Here we report measurements of abundance of 13C-18O bonds (described by the measured parameter Δ47) in a variety of marine calcifiers cultured under controlled conditions. Previous studies on biologically precipitated samples such as foraminifera, coccoliths, and corals have shown that Δ47 values are related to calcification temperature with a relationship that is generally similar to inorganic carbonate. However, the influence of effects other than temperature has not been extensively studied and little work has been done to explore the potential for small non-equilibrium effects in cultured specimens that were grown under controlled conditions. In this study, we report δ18O and Δ47 measurements of mollusk specimens that were cultured at several temperatures ranging from 5 to 25°C, as well as different pH and salinity values. We also report data for other marine calcifiers including the temperate coral species Oculina arbuscula and the coralline red algae Neogoniolithon sp., that were cultured at a single temperature but variable pH.

  16. Inter-laboratory calibration of natural gas round robins for δ2H and δ13C using off-line and on-line techniques

    USGS Publications Warehouse

    Dai, Jinxing; Xia, Xinyu; Li, Zhisheng; Coleman, Dennis D.; Dias, Robert F.; Gao, Ling; Li, Jian; Deev, Andrei; Li, Jin; Dessort, Daniel; Duclerc, Dominique; Li, Liwu; Liu, Jinzhong; Schloemer, Stefan; Zhang, Wenlong; Ni, Yunyan; Hu, Guoyi; Wang, Xiaobo; Tang, Yongchun

    2012-01-01

    Compound-specific carbon and hydrogen isotopic compositions of three natural gas round robins were calibrated by ten laboratories carrying out more than 800 measurements including both on-line and off-line methods. Two-point calibrations were performed with international measurement standards for hydrogen isotope ratios (VSMOW and SLAP) and carbon isotope ratios (NBS 19 and L-SVEC CO2). The consensus δ13C values and uncertainties were derived from the Maximum Likelihood Estimation (MLE) based on off-line measurements; the consensus δ2H values and uncertainties were derived from MLE of both off-line and on-line measurements, taking the bias of on-line measurements into account. The calibrated consensus values in ‰ relative to VSMOW and VPDB are: NG1 (coal-related gas): Methane: δ2HVSMOW = − 185.1‰ ± 1.2‰, δ13CVPDB = − 34.18‰ ± 0.10‰ Ethane: δ2HVSMOW = − 156.3‰ ± 1.8‰, δ13CVPDB = − 24.66‰ ± 0.11‰ Propane: δ2HVSMOW = − 143.6‰ ± 3.3‰, δ13CVPDB = − 22.21‰ ± 0.11‰ i-Butane: δ13CVPDB = − 21.62‰ ± 0.12‰ n-Butane: δ13CVPDB = − 21.74‰ ± 0.13‰ CO2: δ13CVPDB = − 5.00‰ ± 0.12‰ NG2 (biogas): Methane: δ2HVSMOW = − 237.0‰ ± 1.2‰, δ13CVPDB = − 68.89‰ ± 0.12‰ NG3 (oil-related gas): Methane: δ2HVSMOW = − 167.6‰ ± 1.0‰, δ13CVPDB = − 43.61‰ ± 0.09‰ Ethane: δ2HVSMOW = − 164.1‰ ± 2.4‰, δ13CVPDB = − 40.24‰ ± 0.10‰ Propane: δ2HVSMOW = − 138.4‰ ± 3.0‰, δ13CVPDB = − 33.79‰ ± 0.09‰ All of the assigned values are traceable to the international carbon isotope standard of VPDB and hydrogen isotope standard of VSMOW.

  17. Natural abundances of carbon isotopes in acetate from a coastal marine sediment

    NASA Technical Reports Server (NTRS)

    Blair, N. E.; Martens, C. S.; Des Marais, D. J.

    1987-01-01

    Measurements of the natural abundances of carbon isotopes were made in acetate samples isolated from the anoxic marine sediment of Cape Lookout Bight, North Carolina. The typical value of the total acetate carbon isotope ratio (delta 13C) was -16.1 +/- 0.2 per mil. The methyl and carboxyl groups were determined to be -26.4 +/- 0.3 and -6.0 +/- 0.3 per mil, respectively, for one sample. The isotopic composition of the acetate is thought to have resulted from isotopic discriminations that occurred during the cycling of that molecule. Measurements of this type, which have not been made previously in the natural environment, may provide information about the dominant microbial pathways in anoxic sediments as well as the processes that influence the carbon isotopic composition of biogenic methane from many sources.

  18. Site-specific 13C content by quantitative isotopic 13C nuclear magnetic resonance spectrometry: a pilot inter-laboratory study.

    PubMed

    Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S

    2013-07-25

    Isotopic (13)C NMR spectrometry, which is able to measure intra-molecular (13)C composition, is of emerging demand because of the new information provided by the (13)C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic (13)C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular (13)C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic (13)C NMR was then assessed on vanillin from three different origins associated with specific δ (13)Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ (13)Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results. PMID:23845488

  19. Simultaneous imaging of 13C metabolism and 1H structure: technical considerations and potential applications.

    PubMed

    Gordon, Jeremy W; Fain, Sean B; Niles, David J; Ludwig, Kai D; Johnson, Kevin M; Peterson, Eric T

    2015-05-01

    Real-time imaging of (13)C metabolism in vivo has been enabled by recent advances in hyperpolarization. As a result of the inherently low natural abundance of endogenous (13)C nuclei, hyperpolarized (13)C images lack structural information that could be used to aid in motion detection and anatomical registration. Motion before or during the (13)C acquisition can therefore result in artifacts and misregistration that may obscure measures of metabolism. In this work, we demonstrate a method to simultaneously image both (1)H and (13)C nuclei using a dual-nucleus spectral-spatial radiofrequency excitation and a fully coincident readout for rapid multinuclear spectroscopic imaging. With the appropriate multinuclear hardware, and the means to simultaneously excite and receive on both channels, this technique is straightforward to implement requiring little to no increase in scan time. Phantom and in vivo experiments were performed with both Cartesian and spiral trajectories to validate and illustrate the utility of simultaneous acquisitions. Motion compensation of dynamic metabolic measurements acquired during free breathing was demonstrated using motion tracking derived from (1)H data. Simultaneous multinuclear imaging provides structural (1)H and metabolic (13)C images that are correlated both spatially and temporally, and are therefore amenable to joint (1)H and (13)C analysis and correction of structure-function images. PMID:25810146

  20. Molecular indicators for palaeoenvironmental change in a Messinian evaporitic sequence (Vena del Gesso, Italy). II: High-resolution variations in abundances and 13C contents of free and sulphur-bound carbon skeletons in a single marl bed

    NASA Technical Reports Server (NTRS)

    Kenig, F.; Damste, J. S.; Frewin, N. L.; Hayes, J. M.; De Leeuw, J. W.

    1995-01-01

    The extractable organic matter of 10 immature samples from a marl bed of one evaporitic cycle of the Vena del Gesso sediments (Gessoso-solfifera Fm., Messinian, Italy) was analyzed quantitatively for free hydrocarbons and organic sulphur compounds. Nickel boride was used as a desulphurizing agent to recover sulphur-bound lipids from the polar and asphaltene fractions. Carbon isotopic compositions (delta vs PDB) of free hydrocarbons and of S-bound hydrocarbons were also measured. Relationships between these carbon skeletons, precursor biolipids, and the organisms producing them could then be examined. Concentrations of S-bound lipids and free hydrocarbons and their delta values were plotted vs depth in the marl bed and the profiles were interpreted in terms of variations in source organisms, 13 C contents of the carbon source, and environmentally induced changes in isotopic fractionation. The overall range of delta values measured was 24.7%, from -11.6% for a component derived from green sulphur bacteria (Chlorobiaceae) to -36.3% for a lipid derived from purple sulphur bacteria (Chromatiaceae). Deconvolution of mixtures of components deriving from multiple sources (green and purple sulphur bacteria, coccolithophorids, microalgae and higher plants) was sometimes possible because both quantitative and isotopic data were available and because either the free or S-bound pool sometimes appeared to contain material from a single source. Several free n-alkanes and S-bound lipids appeared to be specific products of upper-water-column primary producers (i.e. algae and cyanobacteria). Others derived from anaerobic photoautotrophs and from heterotrophic protozoa (ciliates), which apparently fed partly on Chlorobiaceae. Four groups of n-alkanes produced by algae or cyanobacteria were also recognized based on systematic variations of abundance and isotopic composition with depth. For hydrocarbons probably derived from microalgae, isotopic variations are well correlated with

  1. Calculation of total meal d13C from individual food d13C.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variations in the isotopic signature of carbon in biological samples can be used to distinguish dietary patterns and monitor shifts in metabolism. But for these variations to have meaning, the isotopic signature of the diet must be known. We sought to determine if knowledge of the 13C isotopic abund...

  2. Natural abundance carbon-13 nuclear magnetic resonance studies of histone and DNA dynamics in nucleosome cores.

    PubMed

    Hilliard, P R; Smith, R M; Rill, R L

    1986-05-01

    Natural abundance carbon-13 nuclear magnetic resonance spectra (67.9 MHz) were obtained for native nucleosome cores: cores dissociated in 2 M NaCl and 2 M NaCl, 6 M urea; and cores degraded with DNase I plus proteinase K. Phosphorus-31 NMR spectra of native and dissociated cores and core length DNA were also obtained at 60.7 MHz. The 31P resonance and spin-lattice relaxation time (T1) of DNA were only slightly affected by packaging in nucleosome cores, in agreement with other reports, but 13C resonances of DNA were essentially unobservable. The loss of DNA spectral intensity suggests that rapid internal motions of DNA sugar carbons in protein-free DNA previously demonstrated by 13C NMR methods are partly restricted in nucleosomes. The 13C spectrum of native cores contains many narrow intense resonances assigned to lysine side chain and alpha-carbons, glycine alpha-carbons, alanine alpha- and beta- carbons, and arginine side chain carbons. Several weaker resonances were also assigned. The narrow line widths, short T1 values, and non-minimal nuclear Overhauser enhancements of these resonances, including alpha- and beta-carbons, show that some terminal chain segments of histones in nucleosomes are as mobile as small random coil polypeptides. The mobile segments include about 9% of all histone residues and 25% of all lysines, but only 10% of all arginines. The compositions of these segments indicate that mobile regions are located in amino- or carboxyl-terminal sequences of two or more histones. In addition, high mobility was observed for side chain carbons of 45-50% of all lysines (delta and epsilon carbons) and about 25% of all arginines (zeta carbon) in histones (including those in mobile segments), suggesting that basic residues in terminal histone sequences are not strongly involved in nucleosome structure and may instead help stabilize higher order chromatin structure. PMID:3700380

  3. Paramagnetic relaxation enhancement solid-state NMR studies of heterogeneous catalytic reaction over HY zeolite using natural abundance reactant.

    PubMed

    Zhou, Lei; Li, Shenhui; Su, Yongchao; Li, Bojie; Deng, Feng

    2015-01-01

    Paramagnetic relaxation enhancement solid-state NMR (PRE ssNMR) technique was used to investigate catalytic reaction over zeolite HY. After introducing paramagnetic Cu(II) ions into the zeolite, the enhancement of longitudinal relaxation rates of nearby nuclei, i.e.(29)Si of the framework and (13)C of the absorbents, was measured. It was demonstrated that the PRE ssNMR technique facilitated the fast acquisition of NMR signals to monitor the heterogeneous catalytic reaction (such as acetone to hydrocarbon) using natural abundance reactants. PMID:25616847

  4. Development of new method of δ(13)C measurement for trace hydrocarbons in natural gas using solid phase micro-extraction coupled to gas chromatography isotope ratio mass spectrometry.

    PubMed

    Li, Zhongping; Wang, Xibin; Li, Liwu; Zhang, Mingjie; Tao, Mingxin; Xing, Lantian; Cao, Chunhui; Xia, Yanqing

    2014-11-01

    Compound specific isotope analysis (CSIA) of normal-level hydrocarbons (C1-C4) in natural gas is often successfully used in natural gas origin identification and classification, but little progress so far has been made for trace level hydrocarbons (C5-C14) in natural gas. In this study, we developed a method for rapid analysis of carbon isotopic ratios for trace hydrocarbons in natural gas samples. This method can be described as a combined approach characterized by solid phase micro-extraction (SPME) technique coupled to gas chromatography isotope ratio mass spectrometry (GC/IRMS). In this study, the CAR-PDMS fiber was chosen as the SPME adsorptive material after comparative experiments with other four fibers, and the parameters, including equilibration time, extraction temperature and desorption time, for efficient extraction of trace hydrocarbons were systematically optimized. The results showed the carbon isotopic fractionation was not observed as a function of equilibration time and extraction temperature. And the δ(13)C signatures determined by SPME-GC/IRMS were in good agreement with the known δ(13)C values of C5-C14 measured by GC-IRMS, and the accuracy is generally within ±0.5‰. Five natural gas samples were analyzed using this method, and the δ(13)C values for C5-C14 components were obtained with satisfied repeatability. The SPME-GC/IRMS approach fitted with CAR-PDMS fiber is well suited for the preconcentration of trace hydrocarbons and provides so far the most reliable carbon isotopic analysis for trace compounds in natural gas. PMID:25465020

  5. Directly detected 55Mn MRI: Application to phantoms for human hyperpolarized 13C MRI development

    PubMed Central

    von Morze, Cornelius; Carvajal, Lucas; Reed, Galen D.; Swisher, Christine Leon; Tropp, James; Vigneron, Daniel B.

    2014-01-01

    In this work we demonstrate for the first time directly detected manganese-55 (55Mn) MRI using a clinical 3T MRI scanner designed for human hyperpolarized 13C clinical studies with no additional hardware modifications. Due to the similar frequency of the 55Mn and 13C resonances, the use of aqueous permanganate for large, signal-dense, and cost-effective “13C” MRI phantoms was investigated, addressing the clear need for new phantoms for these studies. Due to 100% natural abundance, higher intrinsic sensitivity, and favorable relaxation properties, 55Mn MRI of aqueous permanganate demonstrates dramatically increased sensitivity over typical 13C phantom MRI, at greatly reduced cost as compared with large 13C-enriched phantoms. A large sensitivity advantage (22-fold) was demonstrated. A cylindrical phantom (d= 8 cm) containing concentrated aqueous sodium permanganate (2.7M) was scanned rapidly by 55Mn MRI in a human head coil tuned for 13C, using a balanced SSFP acquisition. The requisite penetration of RF magnetic fields into concentrated permanganate was investigated by experiments and high frequency electromagnetic simulations, and found to be sufficient for 55Mn MRI with reasonably sized phantoms. A sub-second slice-selective acquisition yielded mean image SNR of ~60 at 0.5cm3 spatial resolution, distributed with minimum central signal ~40% of the maximum edge signal. We anticipate that permanganate phantoms will be very useful for testing HP 13C coils and methods designed for human studies. PMID:25179135

  6. In folio respiratory fluxomics revealed by 13C isotopic labeling and H/D isotope effects highlight the noncyclic nature of the tricarboxylic acid "cycle" in illuminated leaves.

    PubMed

    Tcherkez, Guillaume; Mahé, Aline; Gauthier, Paul; Mauve, Caroline; Gout, Elizabeth; Bligny, Richard; Cornic, Gabriel; Hodges, Michael

    2009-10-01

    While the possible importance of the tricarboxylic acid (TCA) cycle reactions for leaf photosynthesis operation has been recognized, many uncertainties remain on whether TCA cycle biochemistry is similar in the light compared with the dark. It is widely accepted that leaf day respiration and the metabolic commitment to TCA decarboxylation are down-regulated in illuminated leaves. However, the metabolic basis (i.e. the limiting steps involved in such a down-regulation) is not well known. Here, we investigated the in vivo metabolic fluxes of individual reactions of the TCA cycle by developing two isotopic methods, (13)C tracing and fluxomics and the use of H/D isotope effects, with Xanthium strumarium leaves. We provide evidence that the TCA "cycle" does not work in the forward direction like a proper cycle but, rather, operates in both the reverse and forward directions to produce fumarate and glutamate, respectively. Such a functional division of the cycle plausibly reflects the compromise between two contrasted forces: (1) the feedback inhibition by NADH and ATP on TCA enzymes in the light, and (2) the need to provide pH-buffering organic acids and carbon skeletons for nitrate absorption and assimilation. PMID:19675152

  7. Short-term natural δ13C variations in pools and fluxes in a beech forest: the transfer of isotopic signal from recent photosynthates to soil respired CO2

    NASA Astrophysics Data System (ADS)

    Gavrichkova, O.; Proietti, S.; Moscatello, S.; Portarena, S.; Battistelli, A.; Matteucci, G.; Brugnoli, E.

    2011-03-01

    The fate of photosynthetic products within the plant-soil continuum determines how long the reduced carbon resides within the ecosystem and when it returns back to the atmosphere in the form of respiratory CO2. We have tested the possibility of measuring natural variation in δ13C to disentangle potential times needed to transfer carbohydrates produced by photosynthesis down to roots and, in general, to belowground up to its further release in the form of soil respiration into the atmosphere in a beech (Fagus sylvatica) forest. For these purposes we have measured the variation in stable carbon and oxygen isotope compositions in plant material and in soil respired CO2 every three hours for three consequent days. Possible steps and different signs of post-photosynthetic fractionation during carbon translocation were also identified. A 12 h-periodicity was observed for variation in δ13C in soluble sugars in the top crown leaves and it can be explained by starch day/night dynamics in synthesis and breakdown and by stomatal limitations under elevated vapour pressure deficits. Photosynthetic products were transported down the trunk and mixed with older carbon pools, therefore causing the dampening of the δ13C signal variation. The strongest periodicity of 24 h was found in δ13C in soil respiration indicating changes in root contribution to the total CO2 efflux. Nevertheless, it was possible to identify the speed of carbon translocation through the plant-soil continuum. A period of 24 h was needed to transfer the C assimilated by photosynthesis from the top crown leaves to the tree trunk at breast height and additional 3 h for further respiration of that C by roots and soil microorganisms and its to subsequent diffusion back to the atmosphere.

  8. (13)C-Breath testing in animals: theory, applications, and future directions.

    PubMed

    McCue, Marshall D; Welch, Kenneth C

    2016-04-01

    The carbon isotope values in the exhaled breath of an animal mirror the carbon isotope values of the metabolic fuels being oxidized. The measurement of stable carbon isotopes in carbon dioxide is called (13)C-breath testing and offers a minimally invasive method to study substrate oxidation in vivo. (13)C-breath testing has been broadly used to study human exercise, nutrition, and pathologies since the 1970s. Owing to reduced use of radioactive isotopes and the increased convenience and affordability of (13)C-analyzers, the past decade has witnessed a sharp increase in the use of breath testing throughout comparative physiology-especially to answer questions about how and when animals oxidize particular nutrients. Here, we review the practical aspects of (13)C-breath testing and identify the strengths and weaknesses of different methodological approaches including the use of natural abundance versus artificially-enriched (13)C tracers. We critically compare the information that can be obtained using different experimental protocols such as diet-switching versus fuel-switching. We also discuss several factors that should be considered when designing breath testing experiments including extrinsic versus intrinsic (13)C-labelling and different approaches to model nutrient oxidation. We use case studies to highlight the myriad applications of (13)C-breath testing in basic and clinical human studies as well as comparative studies of fuel use, energetics, and carbon turnover in multiple vertebrate and invertebrate groups. Lastly, we call for increased and rigorous use of (13)C-breath testing to explore a variety of new research areas and potentially answer long standing questions related to thermobiology, locomotion, and nutrition. PMID:26660654

  9. Animal /sup 13/C//sup 12/C correlates with trophic level in pelagic food webs

    SciTech Connect

    Rau, G.H.; Mearns, A.J.; Young, D.R.; Olson, R.J.; Schafer, H.A.; Kaplan, I.R.

    1983-01-01

    Whatever the underlying cause(s), our observations further substantiate the existence of small but progressive increases in animal tissue /sup 13/C//sup 12/C with increasing trophic level. Such a relationship has significant implications for the use of stable carbon isotope natural abundance in animal tissues or remains, in order to interpret the tropic structure and food base of past as well as present-day animal communities. The delta/sup 13/C of the marine animal tissues analyzed ranged from -20.6 to -15.8%. The macro-fauna from the eastern tropical Pacific Ocean had higher isotope values than the net plankton collected from the same area. The average increases in delta/sup 13/C per trophic level were 0.73 and 1.38% for the California coastal waters and for the eastern tropical Pacific, respectively. These isotopic increases approximate closely those previously reported to occur within single trophic level steps.

  10. Chlorine-36 abundance in natural and synthetic perchlorate

    SciTech Connect

    Heikoop, Jeffrey M; Dale, M; Sturchio, Neil C; Caffee, M; Belosa, A D; Heraty, Jr., L J; Bohike, J K; Hatzinger, P B; Jackson, W A; Gu, B

    2009-01-01

    Perchlorate (ClO{sub 4}{sup -}) is ubiquitous in the environment. It occurs naturally as a product of atmospheric photochemical reactions, and is synthesized for military, aerospace, and industrial applications. Nitrate-enriched soils of the Atacama Desert (Chile) contain high concentrations of natural ClO{sub 4}{sup -}; nitrate produced from these soils has been exported worldwide since the mid-1800's for use in agriculture. The widespread introduction of synthetic and agricultural ClO{sub 4}{sup -} into the environment has complicated attempts to understand the geochemical cycle of ClO{sub 4}{sup -}. Natural ClO{sub 4}{sup -} samples from the southwestern United States have relatively high {sup 36}Cl abundances ({sup 36}Cl/Cl = 3,100 x 10{sup -15} to 28,800 x 10{sup -15}), compared with samples of synthetic ({sup 36}Cl/Cl = 0.0 x 10{sup -15} to 40 x 10{sup -15}) and Atacama Desert ({sup 36}Cl/Cl = 0.9 x 10{sup -15} to 590 x 10{sup -15}) ClO{sub 4}{sup -}. These data give a lower limit for the initial {sup 36}Cl abundance of natural ClO{sub 4}{sup -} and provide temporal and other constraints on its geochemical cycle.

  11. 1H, 13C and 15N NMR assignments of the E. coli peptide deformylase in complex with a natural inhibitor called actinonin.

    PubMed

    Larue, Valéry; Seijo, Bili; Tisne, Carine; Dardel, Frédéric

    2009-06-01

    In eubacteria, the formyl group of nascent polypeptides is removed by peptide deformylase protein (PDF). This is the reason why PDF has received special attention in the course of the search for new antibacterial agents. We observed by NMR that actinonin, a natural inhibitor, induced drastic changes in the HSQC spectrum of E. coli PDF. We report here the complete NMR chemical shift assignments of PDF resonances bound to actinonin. PMID:19636969

  12. Paper Thermoelectrics: Merging Nanotechnology with Naturally Abundant Fibrous Material.

    PubMed

    Sun, Chengjun; Goharpey, Amir Hossein; Rai, Ayush; Zhang, Teng; Ko, Dong-Kyun

    2016-08-31

    The development of paper-based sensors, antennas, and energy-harvesting devices can transform the way electronic devices are manufactured and used. Herein we describe an approach to fabricate paper thermoelectric generators for the first time by directly impregnating naturally abundant cellulose materials with p- or n-type colloidal semiconductor quantum dots. We investigate Seebeck coefficients and electrical conductivities as a function of temperature between 300 and 400 K as well as in-plane thermal conductivities using Angstrom's method. We further demonstrate equipment-free fabrication of flexible thermoelectric modules using p- and n-type paper strips. Leveraged by paper's inherently low thermal conductivity and high flexibility, these paper modules have the potential to efficiently utilize heat available in natural and man-made environments by maximizing the thermal contact to heat sources of arbitrary geometry. PMID:27505304

  13. Factors determining δ13C and δ18O fractionation in aragonitic otoliths of marine fish

    NASA Astrophysics Data System (ADS)

    Thorrold, Simon R.; Campana, Steven E.; Jones, Cynthia M.; Swart, Peter K.

    1997-07-01

    Fish otoliths are aragonitic accretions located within the inner ear of teleost fish. The acellular nature of otoliths, along with taxon-specific shapes, chronological growth increments, and abundance in the fossil record suggest that the stable isotope chemistry of these structures may be unique recorders of environmental conditions experienced by fish in both modern and ancient water masses. To assess the factors determining δ 13C and δ 18O fractionation in fish otoliths, we reared Atlantic croaker ( Micropogonias undulatus) larvae under controlled environmental conditions. Metabolic effects apparently generated large isotopic disequilibria in the δ 13C values of M. undulatus otoliths. We found evidence of a negative regression between δ 13C- carbonate-δ 13C water (δ 13C) and temperature: δ 13C = -1.78 - 0.18 T °C However, this relationship was aliased to a degree by a positive correlation between δ 13C and somatic growth and otolith precipitation rates. Oxygen isotopes were deposited close to equilibrium with the ambient water. The relationship between temperature and the 18O/ 16O fractionation factor (α) was determined empirically to be: 1000 ln α = 18.56(10 3T K -1) - 32.54 The fractionation factor was not affected by either otolith precipitation or fish growth rates. Reconstruction of water temperature histories should, therefore, be possible from the δ 18O values of M. undulatus otoliths with a precision of 1°C, providing the δ 18O of the ambient water can be estimated.

  14. Directly detected (55)Mn MRI: application to phantoms for human hyperpolarized (13)C MRI development.

    PubMed

    von Morze, Cornelius; Carvajal, Lucas; Reed, Galen D; Swisher, Christine Leon; Tropp, James; Vigneron, Daniel B

    2014-12-01

    In this work we demonstrate for the first time directly detected manganese-55 ((55)Mn) magnetic resonance imaging (MRI) using a clinical 3T MRI scanner designed for human hyperpolarized (13)C clinical studies with no additional hardware modifications. Due to the similar frequency of the (55)Mn and (13)C resonances, the use of aqueous permanganate for large, signal-dense, and cost-effective "(13)C" MRI phantoms was investigated, addressing the clear need for new phantoms for these studies. Due to 100% natural abundance, higher intrinsic sensitivity, and favorable relaxation properties, (55)Mn MRI of aqueous permanganate demonstrates dramatically increased sensitivity over typical (13)C phantom MRI, at greatly reduced cost as compared with large (13)C-enriched phantoms. A large sensitivity advantage (22-fold) was demonstrated. A cylindrical phantom (d=8 cm) containing concentrated aqueous sodium permanganate (2.7 M) was scanned rapidly by (55)Mn MRI in a human head coil tuned for (13)C, using a balanced steady state free precession acquisition. The requisite penetration of radiofrequency magnetic fields into concentrated permanganate was investigated by experiments and high frequency electromagnetic simulations, and found to be sufficient for (55)Mn MRI with reasonably sized phantoms. A sub-second slice-selective acquisition yielded mean image signal-to-noise ratio of ~60 at 0.5 cm(3) spatial resolution, distributed with minimum central signal ~40% of the maximum edge signal. We anticipate that permanganate phantoms will be very useful for testing HP (13)C coils and methods designed for human studies. PMID:25179135

  15. Short-term natural δ13C and δ18O variations in pools and fluxes in a beech forest: the transfer of isotopic signal from recent photosynthates to soil respired CO2

    NASA Astrophysics Data System (ADS)

    Gavrichkova, O.; Proietti, S.; Moscatello, S.; Portarena, S.; Battistelli, A.; Matteucci, G.; Brugnoli, E.

    2011-10-01

    The fate of photosynthetic products within the plant-soil continuum determines how long the reduced carbon resides within the ecosystem and when it returns back to the atmosphere in the form of respiratory CO2. We have tested the possibility of measuring natural variation in δ13C and δ18O to disentangle the potential times needed to transfer carbohydrates produced by photosynthesis down to trunk, roots and, in general, to belowground up to its further release in the form of soil respiration into the atmosphere in a beech (Fagus sylvatica) forest. We have measured the variation in stable carbon and oxygen isotope compositions in plant material and in soil respired CO2 every three hours for three consecutive days. Possible steps and different signs of post-photosynthetic fractionation during carbon translocation were also identified. A 12 h-periodicity was observed for variation in δ13C in soluble sugars in the top crown leaves and it can be explained by starch day/night dynamics in synthesis and breakdown and by stomatal limitations under elevated vapour pressure deficits. Photosynthetic products were transported down the trunk and mixed with older carbon pools, therefore causing the dampening of the δ13C signal variation. The strongest periodicity of 24 h was found in δ13C in soil respiration indicating changes in root contribution to the total CO2 efflux. Other non-biological causes like diffusion fractionation and advection induced by gas withdrawn from the measurement chamber complicate data interpretation on this step of C transfer path. Nevertheless, it was possible to identify the speed of carbohydrates' translocation from the point of assimilation to the trunk breast height because leaf-imprinted enrichment of δ18O in soluble sugars was less modified along the downward transport and was well related to environmental parameters potentially linked to stomatal conductance. The speed of carbohydrates translocation from the site of assimilation to the trunk

  16. Paleoclimate reconstruction:natural abundance of d13C and d15N of modern plant pollen to interpret fossil data

    NASA Astrophysics Data System (ADS)

    Descolas-Gros, C.

    2003-04-01

    δ13 values of modern plant organic carbon allow the differentiation of the different physiological plant categories. The geographical distribution of these plants according to their photosynthetic pathways provides informations on the modifications of climatic parameters (pCO_2, temperature, rainfall...). δ13 variability of organic carbon of fossil plants enables us to interpret geographical plants distribution and associated climatic parameters over geological time. In order to do parametrisation of these relationships, well preserved molecules are suited. Sporopollenin which is the main constituent of the external part of pollen grain is well preserved in paleosediments. This makes of this molecule an interesting tool for paleovegetation reconstructions. The interest of δ15N associated measurements is demonstrated. These different aspects were discussed with our results and those of the litterature.

  17. In search of the mechanisms behind soil carbon metabolism of a Douglas fir forest in complex terrain using naturally abundant 13C

    NASA Astrophysics Data System (ADS)

    Kayler, Z. E.; Sulzman, E. W.; Barnard, H. R.; Kennedy, A.; Phillips, C.; Mix, A.; Bond, B. J.

    2008-12-01

    Soil is well known for being highly variable, spatially and temporally, in moisture, texture, nutrients, carbon content and organisms. The magnitude of variation in soil characteristics represented in a study is, in part, determined by the choice in site location. Choosing sites that are topographically flat reduces variability due to environmental gradients, variability that is amplified in sites of complex terrain. We measured soil respiration, an integrative measure of ecosystem biological and physical processes, and its isotopic signature (δ13CR-s) to accomplish two goals: 1. Explore how gradients in temperature and moisture within a steeply sloped watershed affect the flux and isotopic signature of soil CO2 2. Deconvolve the isotopic signature of soil respiration into autotrophic and heterotrophic sources using a multi-source mixing model constrained by samples of soil organic matter and water soluble extracts of leaf foliage. Our site is located in a steep catchment within the central Cascades of Oregon (HJ Andrews LTER) where we made respiration measurements in plots established along side a sensor transect that continuously measures soil moisture and temperature; air relative humidity and temperature; and tree transpiration. There was a distinct difference in soil metabolism between the south and north aspects in the watershed. Temperature-corrected basal respiration of the south facing slope was 1 μmol m-2s-1 greater than the north facing slope. There was also a difference in isotopic signature between the two slopes that could be as great as 2 per mil depending on the period within the growing season. The strength of the correlation between environmental variables and soil carbon flux was non-uniform across the catchment. There was, however, a strong positive correlation between soil flux with recent transpiration rates (0 to 3 days prior) as well as with transpiration rates that occurred up to 9 days previously. This pattern was especially prevalent for locations near the ridge of each slope and dampened with a decrease in plot elevation. The correlation between δ13CR-s and transpiration, as well as vapor pressure deficit, was similar with a high degree of correlation that occurred 0-3 and 8 days before sampling. The correlation analysis suggests that soil flux in this forest is primarily controlled by aboveground inputs throughout the growing season. The source partitioning analysis confirms this observation although the magnitude of the aboveground contribution varies with season and topographic position.

  18. Regioselective syntheses of [13C]4-labelled sodium 1-carboxy-2-(2-ethylhexyloxycarbonyl)ethanesulfonate and sodium 2-carboxy-1-(2-ethylhexyloxycarbonyl)ethanesulfonate from [13C]4-maleic anhydride.

    PubMed

    Barsamian, Adam L; Perkins, Matt J; Field, Jennifer A; Blakemore, Paul R

    2014-05-15

    The entitled monohydrolysis products, also known as α-ethylhexyl and β-ethylhexyl sulfosuccinate (EHSS), of the surfactant diisooctyl sulfosuccinate (DOSS) were synthesized in stable isotope-labelled form from [(13)C]4 -maleic anhydride. Sodium [(13)C]4 -1-carboxy-2-(2-ethylhexyloxycarbonyl)ethanesulfonate (α-EHSS) was prepared by the method of Larpent by reaction of 2-ethylhexan-1-ol with [(13)C]4 -maleic anhydride followed by regioselective conjugate addition of sodium bisulfite to the resulting monoester (38% overall yield). The regiochemical outcome of bisulfite addition was confirmed by a combination of (13)C/(13)C (incredible natural abundance double quantum transfer) and (1)H/(13)C (heteronuclear multiple-bond correlation (HMBC)) NMR spectral correlation experiments. Sodium [(13)C]4 -2-carboxy-1-(2-ethylhexyloxycarbonyl)ethanesulfonate (β-EHSS) was prepared in four steps by reaction of 4-methoxybenzyl alcohol with [(13)C]4 -maleic anhydride, regioselective sodium bisulfite addition, N,N'-dicyclohexylcarbodiimide-mediated esterification with 2-ethylhexan-1-ol, and p-methoxybenzyl ester deprotection with trifluoroacetic acid (13% overall yield). The regiochemical outcome of the second synthesis was confirmed by a combination of (1)JCC scalar coupling constant analysis and (1)H/(13)C (HMBC) NMR spectral correlation. The materials prepared are required as internal standards for the liquid chromatography-mass spectrometry (LC-MS)/MS trace analysis of the degradation products of DOSS, the anionic surfactant found in Corexit, the oil dispersant used during emergency response efforts connected to the Deepwater Horizon oil spill of April 2010. PMID:24700711

  19. {sup 13}C chemical shift anisotropies for carbonate ions in cement minerals and the use of {sup 13}C, {sup 27}Al and {sup 29}Si MAS NMR in studies of Portland cement including limestone additions

    SciTech Connect

    Sevelsted, Tine F.; Herfort, Duncan

    2013-10-15

    {sup 13}C isotropic chemical shifts and chemical shift anisotropy parameters have been determined for a number of inorganic carbonates relevant in cement chemistry from slow-speed {sup 13}C MAS or {sup 13}C({sup 1}H) CP/MAS NMR spectra (9.4 T or 14.1 T) for {sup 13}C in natural abundance. The variation in the {sup 13}C chemical shift parameters is relatively small, raising some doubts that different carbonate species in Portland cement-based materials may not be sufficiently resolved in {sup 13}C MAS NMR spectra. However, it is shown that by combining {sup 13}C MAS and {sup 13}C({sup 1}H) CP/MAS NMR carbonate anions in anhydrous and hydrated phases can be distinguished, thereby providing valuable information about the reactivity of limestone in cement blends. This is illustrated for three cement pastes prepared from an ordinary Portland cement, including 0, 16, and 25 wt.% limestone, and following the hydration for up to one year. For these blends {sup 29}Si MAS NMR reveals that the limestone filler accelerates the hydration for alite and also results in a smaller fraction of tetrahedrally coordinated Al incorporated in the C-S-H phase. The latter result is more clearly observed in {sup 27}Al MAS NMR spectra of the cement–limestone blends and suggests that dissolved aluminate species in the cement–limestone blends readily react with carbonate ions from the limestone filler, forming calcium monocarboaluminate hydrate. -- Highlights: •{sup 13}C chemical shift anisotropies for inorganic carbonates from {sup 13}C MAS NMR. •Narrow {sup 13}C NMR chemical shift range (163–171 ppm) for inorganic carbonates. •Anhydrous and hydrated carbonate species by {sup 13}C MAS and {sup 13}C({sup 1}H) CP/MAS NMR. •Limestone accelerates the hydration for alite in Portland – limestone cements. •Limestone reduces the amount of aluminium incorporated in the C-S-H phase.

  20. Study of Urban environmental quality through Isotopes δ13C

    NASA Astrophysics Data System (ADS)

    González-Sosa, E.; Mastachi-Loza, C.; Becerril-Piña, R.; Ramos-Salinas, N. M.

    2012-04-01

    Usually, trees with similar pH values on their bark develop epiphytes of similar species, the acidity to be a factor for growth. The aim of the study was evaluate the air quality through isotope δ13C in order to define the levels of environmental quality in the city of Queretaro, Mexico. In this work were collected at least 4 epiphytes positioned in trees of the species Prosopis Laevigata at 25 sites of Queretaro City. The samples were analyzed for trace elements with an inductively coupled plasma atomic emission spectroscopy (ICP). The collecting took place during dry period, in May and early rain June 2011 period, and on four sectors to identify the spatial distribution of pollution, using isotopic analysis of concentration of δ 13C. According with the results there are significant differences among the species in each of the sampled areas. The 5 February Avenue presented greater diversity and richness of δ13C, followed by those who were surveyed in the proximity of the UAQ and finally in the middle-east area. An average value of δ13C-17.92%, followed by those surveyed in the vicinity of the UAQ that correspond to sector I and II with an concentration of δ13C-17.55% and δ13C-17.22%, and finally the samples collected in trees scattered in the East-Sector II and IV with a value of δ13C-17.02% and δ13C-15.62%, respectively. Also were observed differences between the dry and wet period. It is likely that these results of δ 13C in moist period reflect the drag of the isotopes due to rain events that could mark a trend in the dilution of this element, however there is a trend in terms of abundance and composition of finding more impact in those species sampled in dry period, in May and early June 2011.

  1. Diversity and abundance of phosphonate biosynthetic genes in nature

    PubMed Central

    Yu, Xiaomin; Doroghazi, James R.; Janga, Sarath C.; Zhang, Jun Kai; Circello, Benjamin; Griffin, Benjamin M.; Labeda, David P.; Metcalf, William W.

    2013-01-01

    Phosphonates, molecules containing direct carbon–phosphorus bonds, compose a structurally diverse class of natural products with interesting and useful biological properties. Although their synthesis in protozoa was discovered more than 50 y ago, the extent and diversity of phosphonate production in nature remains poorly characterized. The rearrangement of phosphoenolpyruvate (PEP) to phosphonopyruvate, catalyzed by the enzyme PEP mutase (PepM), is shared by the vast majority of known phosphonate biosynthetic pathways. Thus, the pepM gene can be used as a molecular marker to examine the occurrence and abundance of phosphonate-producing organisms. Based on the presence of this gene, phosphonate biosynthesis is common in microbes, with ∼5% of sequenced bacterial genomes and 7% of genome equivalents in metagenomic datasets carrying pepM homologs. Similarly, we detected the pepM gene in ∼5% of random actinomycete isolates. The pepM-containing gene neighborhoods from 25 of these isolates were cloned, sequenced, and compared with those found in sequenced genomes. PEP mutase sequence conservation is strongly correlated with conservation of other nearby genes, suggesting that the diversity of phosphonate biosynthetic pathways can be predicted by examining PEP mutase diversity. We used this approach to estimate the range of phosphonate biosynthetic pathways in nature, revealing dozens of discrete groups in pepM amplicons from local soils, whereas hundreds were observed in metagenomic datasets. Collectively, our analyses show that phosphonate biosynthesis is both diverse and relatively common in nature, suggesting that the role of phosphonate molecules in the biosphere may be more important than is often recognized. PMID:24297932

  2. Monitoring electron donor metabolism under variable electron acceptor conditions using 13C-labeled lactate

    NASA Astrophysics Data System (ADS)

    Bill, M.; Conrad, M. E.; Yang, L.; Beller, H. R.; Brodie, E. L.

    2010-12-01

    Three sets of flow-through columns constructed with aquifer sediment from Hanford (WA) were used to study reduction of Cr(VI) to poorly soluble Cr(III) under denitrifying, sulfate-reducing/fermentative, and iron-reducing conditions with lactate as the electron donor. In order to understand the relationship between electron donors and biomarkers, and to determine the differences in carbon isotope fractionation resulting from different microbial metabolic processes, we monitored the variation in carbon isotopes in dissolved inorganic carbon (DIC), in total organic carbon (TOC), and in lactate, acetate and propionate. The greatest enrichment in 13C in columns was observed under denitrifying conditions. The δ13C of DIC increased by ~1750 to ~2000‰ fifteen days after supplementation of natural abundance lactate with a 13C-labeled lactate tracer (for an influent δ13C of ~2250‰ for the lactate) indicating almost complete oxidation of the electron donor. The denitrifying columns were among the most active columns and had the highest cell counts and the denitrification rate was highly correlated with Cr(VI) reduction rate. δ13C values of DIC ranged from ~540 to ~1170‰ for iron-reducing conditions. The lower enrichment in iron columns was related to the lower biological activity observed with lower yields of RNA and cell numbers in the column effluents. The carbon isotope shift in the sulfate-reducing ~198 to ~1960‰ for sulfate-reducing conditions reflecting the lower levels of the lactate in these columns. Additionally, in two of the sulfate columns, almost complete fermentation of the lactate occurred, producing acetate and propionate with the labeled carbon signature, but relatively smaller amounts of inorganic carbon. For all electron-accepting conditions, TOC yielded similar δ13C values as lactate stock solutions. Differences in C use efficiency, metabolic rate or metabolic pathway contributed to the differing TOC δ13C to DIC δ13C ratios between treatments

  3. Liquid chromatography combined with mass spectrometry for 13C isotopic analysis in life science research.

    PubMed

    Godin, Jean-Philippe; Fay, Laurent-Bernard; Hopfgartner, Gérard

    2007-01-01

    Among the different disciplines covered by mass spectrometry, measurement of (13)C/(12)C isotopic ratio crosses a large section of disciplines from a tool revealing the origin of compounds to more recent approaches such as metabolomics and proteomics. Isotope ratio mass spectrometry (IRMS) and molecular mass spectrometry (MS) are the two most mature techniques for (13)C isotopic analysis of compounds, respectively, for high and low-isotopic precision. For the sample introduction, the coupling of gas chromatography (GC) to either IRMS or MS is state of the art technique for targeted isotopic analysis of volatile analytes. However, liquid chromatography (LC) also needs to be considered as a tool for the sample introduction into IRMS or MS for (13)C isotopic analyses of non-volatile analytes at natural abundance as well as for (13)C-labeled compounds. This review presents the past and the current processes used to perform (13)C isotopic analysis in combination with LC. It gives particular attention to the combination of LC with IRMS which started in the 1990's with the moving wire transport, then subsequently moved to the chemical reaction interface (CRI) and was made commercially available in 2004 with the wet chemical oxidation interface (LC-IRMS). The LC-IRMS method development is also discussed in this review, including the possible approaches for increasing selectivity and efficiency, for example, using a 100% aqueous mobile phase for the LC separation. In addition, applications for measuring (13)C isotopic enrichments using atmospheric pressure LC-MS instruments with a quadrupole, a time-of-flight, and an ion trap analyzer are also discussed as well as a LC-ICPMS using a prototype instrument with two quadrupoles. PMID:17853432

  4. Large and unexpected enrichment in stratospheric 16O13C18O and its meridional variation

    PubMed Central

    Yeung, Laurence Y.; Affek, Hagit P.; Hoag, Katherine J.; Guo, Weifu; Wiegel, Aaron A.; Atlas, Elliot L.; Schauffler, Sue M.; Okumura, Mitchio; Boering, Kristie A.; Eiler, John M.

    2009-01-01

    The stratospheric CO2 oxygen isotope budget is thought to be governed primarily by the O(1D)+CO2 isotope exchange reaction. However, there is increasing evidence that other important physical processes may be occurring that standard isotopic tools have been unable to identify. Measuring the distribution of the exceedingly rare CO2 isotopologue 16O13C18O, in concert with 18O and 17O abundances, provides sensitivities to these additional processes and, thus, is a valuable test of current models. We identify a large and unexpected meridional variation in stratospheric 16O13C18O, observed as proportions in the polar vortex that are higher than in any naturally derived CO2 sample to date. We show, through photochemical experiments, that lower 16O13C18O proportions observed in the midlatitudes are determined primarily by the O(1D)+CO2 isotope exchange reaction, which promotes a stochastic isotopologue distribution. In contrast, higher 16O13C18O proportions in the polar vortex show correlations with long-lived stratospheric tracer and bulk isotope abundances opposite to those observed at midlatitudes and, thus, opposite to those easily explained by O(1D)+CO2. We believe the most plausible explanation for this meridional variation is either an unrecognized isotopic fractionation associated with the mesospheric photochemistry of CO2 or temperature-dependent isotopic exchange on polar stratospheric clouds. Unraveling the ultimate source of stratospheric 16O13C18O enrichments may impose additional isotopic constraints on biosphere–atmosphere carbon exchange, biosphere productivity, and their respective responses to climate change. PMID:19564595

  5. Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA.

    PubMed

    Mroue, Kamal H; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H; Morris, Michael D; Ramamoorthy, Ayyalusamy

    2014-07-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA=Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the (1)H T1 values were calculated from data collected by (1)H spin-inversion recovery method detected in natural-abundance (13)C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the (1)H T1 values can be successfully reduced by a factor of 3.5 using as low as 10mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the (13)C CPMAS spectra. These results obtained from (13)C-detected CPMAS experiments were further confirmed using (1)H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans. PMID:24881032

  6. Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA

    NASA Astrophysics Data System (ADS)

    Mroue, Kamal H.; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy

    2014-07-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA = Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10 mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans.

  7. Acceleration of Natural-Abundance Solid-State MAS NMR Measurements on Bone by Paramagnetic Relaxation from Gadolinium-DTPA

    PubMed Central

    Mroue, Kamal H.; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy

    2014-01-01

    Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA = Diethylenetriamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10 mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans. PMID:24881032

  8. Strength and limits using 13C phospholipid fatty acid analysis in soil ecology

    NASA Astrophysics Data System (ADS)

    Watzinger, Andrea

    2016-04-01

    This presentation on microbial phospholipid biomarkers, their isotope analysis and their ability to reveal soil functions summarizes experiences gained by the author for more than 10 years. The amount and composition of phospholipid fatty acids (PLFAs) measured in environmental samples strongly depend on the methodology. To achieve comparable results the extraction, separation and methylation method must be kept constant. PLFAs patterns are sensitive to microbial community shifts even though the taxonomic resolution of PLFAs is low. The possibility to easily link lipid biomarkers with stable isotope techniques is identified as a major advantage when addressing soil functions. Measurement of PLFA isotopic ratios is sensitive and enables detecting isotopic fractionation. The difference between the carbon isotopic ratio of single PLFAs and their substrate (δ13C) can vary between -6 and +11‰. This difference derives from the fractionation during biosynthesis and from substrate inhomogeneity. Consequently, natural abundance studies are restricted to quantifying substrate uptake of the total microbial biomass. In contrast, artificial labelling enables quantifying carbon uptake into single PLFAs, but labelling success depends on homogeneous and undisturbed label application. Current developments in microbial ecology (e.g. 13C and 15N proteomics) and isotope techniques (online monitoring of CO2 isotope ratios) will likely improve soil functional interpretations in the future. 13C PLFA analysis will continue to contribute because it is affordable, sensitive and allows frequent sampling combined with the use of small amounts of 13C label.

  9. Two new organic reference materials for δ13C and δ15N measurements and a new value for the δ13C of NBS 22 oil

    USGS Publications Warehouse

    Qi, Haiping; Coplen, Tyler B.; Geilmann, Heike; Brand, Willi A.; Bohlke, John Karl

    2003-01-01

    Analytical grade L-glutamic acid is chemically stable and has a C/N mole ratio of 5, which is close to that of many of natural biological materials, such as blood and animal tissue. Two L-glutamic acid reference materials with substantially different 13C and 15N abundances have been prepared for use as organic reference materials for C and N isotopic measurements. USGS40 is analytical grade L-glutamic acid and has a δ13C value of −26.24‰ relative to VPDB and a δ15N value of −4.52‰ relative to N2 in air. USGS41 was prepared by dissolving analytical grade L-glutamic acid with L-glutamic acid enriched in 13C and 15N. USGS41 has a δ13C value of +37.76‰ and a δ15N value of +47.57‰. The δ13C and δ15N values of both materials were measured against the international reference materials NBS 19 calcium carbonate (δ13C = +1.95‰), L-SVEC lithium carbonate (δ13C = −46.48‰), IAEA-N-1 ammonium sulfate (δ15N = 0.43‰), and USGS32 potassium nitrate (δ15N = 180‰) by on-line combustion continuous-flow and off-line dual-inlet isotope-ratio mass spectrometry. Both USGS40 and USGS41 are isotopically homogeneous; reproducibility of δ13C is better than 0.13‰, and that of δ15N is better than 0.13‰ in 100-μg amounts. These two isotopic reference materials can be used for (i) calibrating local laboratory reference materials, and (ii) quantifying drift with time, mass-dependent fractionations, and isotope-ratio-scale contraction in the isotopic analysis of various biological materials. Isotopic results presented in this paper yield a δ13C value for NBS 22 oil of −29.91‰, in contrast to the commonly accepted value of −29.78‰ for which off-line blank corrections probably have not been quantified satisfactorily.

  10. Study and validity of 13C stable carbon isotopic ratio analysis by mass spectrometry and 2H site-specific natural isotopic fractionation by nuclear magnetic resonance isotopic measurements to characterize and control the authenticity of honey.

    PubMed

    Cotte, J F; Casabianca, H; Lhéritier, J; Perrucchietti, C; Sanglar, C; Waton, H; Grenier-Loustalot, M F

    2007-01-16

    Honey samples were analyzed by stable carbon isotopic ratio analysis by mass spectrometry (SCIRA-MS) and site-specific natural isotopic fractionation measured by nuclear magnetic resonance (SNIF-NMR) to first determine their potentials for characterizing the substance and then to combat adulteration. Honey samples from several geographic and botanical origins were analyzed. The delta(13)C parameter was not significant for characterizing an origin, while the (D/H)(I) ratio could be used to differentiate certain single-flower varieties. Application of the official control method of adding a C(4) syrup (AOAC official method 998.12) to our authentic samples revealed anomalies resulting from SCIRA indices that were more negative than -1 per thousand (permil). A filtration step was added to the experimental procedure and provided results that were compliant with the natural origin of our honey samples. In addition, spiking with a C(4) syrup could be detected starting at 9-10%. The use of SNIF-NMR is limited by the detection of a syrup spike starting only at 20%, which is far from satisfying. PMID:17386484

  11. Anomalous 13C enrichment in modern marine organic carbon

    USGS Publications Warehouse

    Arthur, M.A.; Dean, W.E.; Claypool, G.E.

    1985-01-01

    Marine organic carbon is heavier isotopically (13C enriched) than most land-plant or terrestrial organic C1. Accordingly, ??13C values of organic C in modern marine sediments are routinely interpreted in terms of the relative proportions of marine and terrestrial sources of the preserved organic matter2,3. When independent geochemical techniques are used to evaluate the source of organic matter in Cretaceous or older rocks, those rocks containing mostly marine organic C are found typically to have lighter (more-negative) ??13C values than rocks containing mostly terrestrial organic C. Here we conclude that marine photosynthesis in mid-Cretaceous and earlier oceans generally resulted in a greater fractionation of C isotopes and produced organic C having lighter ??13C values. Modern marine photosynthesis may be occurring under unusual geological conditions (higher oceanic primary production rates, lower PCO2) that limit dissolved CO2 availability and minimize carbon isotope fractionation4. ?? 1985 Nature Publishing Group.

  12. Vertical δ13C and δ15N changes during pedogenesis

    NASA Astrophysics Data System (ADS)

    Brunn, Melanie; Spielvogel, Sandra; Wells, Andrew; Condron, Leo; Oelmann, Yvonne

    2015-04-01

    The natural abundance of soil organic matter (SOM) stable C and N isotope ratios are subjected to vertical changes throughout the soil profile. This vertical distribution is a widely reported phenomenon across varieties of ecosystems and constitutes important insights of soil carbon cycling. In most ecosystems, SOM becomes enriched in heavy isotopes by several per mill in the first few centimeters of the topsoil. The enrichment of 13C in SOM with soil depth is attributed to biological and physical-chemical processes in soil e.g., plant physiological impacts, microbial decomposition, sorption and transport processes. Such vertical trends in 13C and 15N abundance have rarely been related to SOM composition during pedogenesis. The aims of our study were to investigate short and long-term δ13C and δ15N depth changes and their interrelations under progressing pedogenesis and ecosystem development. We sampled soils across the well studied fordune progradation Haast-chronosequence, a dune ridge system under super-humid climate at the West Coast of New Zealand's South Island (43° 53' S, 169° 3' E). Soils from 11 sites with five replicates each covered a time span of around 2870 yr of soil development (from Arenosol to Podzol). Vertical changes of δ13C and δ15N values of SOM were investigated in the organic layers and in 1-cm depth intervals of the upper 10 cm of the mineral soil. With increasing soil depth SOM became enriched in δ13C by 1.9 ± SE 0.1 o and in δ15N by 6.0 ± 0.4 ‰˙Litter δ13C values slightly decreased with increasing soil age (r = -0.61; p = 0.00) likely due to less efficient assimilation linked to nutrient limitations. Fractionation processes during mycorrhizal transfer appeared to affect δ15N values in the litter. We found a strong decrease of δ15N in the early succession stages ≤ 300 yr B.P. (r = -0.95; p = 0.00). Positive relations of vertical 13C and 15N enrichment with soil age might be related to decomposition and appeared to be

  13. Convenient synthesis of nickel (5,7,12,14,19,21,26,28- sup 13 C sub 8 )phthalocyanine

    SciTech Connect

    Barrett, A.G.M.; Broderick, W.E.; Hoffman, B.M.; Velazquez, C.S. )

    1989-06-23

    Metallophthalocyanines are convenient precursors for diverse low-dimensional electrical conductors. Recently we wished to prepare large quantities of nickel (5,7,12,14,19,21,26,28-{sup 13}C{sub 8})phthalocyanine (4) with high isotopic enrichment. Previously macrocycle 4 had been prepared at five times natural abundance by the cyclization of 1,2-dicyanobenzene (3). The partially labeled 1,2-dicyanobenzene (3) in turn was prepared from {sup 13}C-enriched potassium cyanide through the use of copper(I) cyanide. However, we were reluctant to employ this methodology to achieve greater enrichment because of the high cost of 99% potassium ({sup 13}C)cyanide and low overall yield of the process. Herein we report an efficient method to prepare 4 using (arene)tricarbonylchromium chemistry.

  14. Novel Peak Assignments of in Vivo 13C MRS in Human Brain at 1.5 T

    NASA Astrophysics Data System (ADS)

    Blüml, Stefan; Hwang, Jong-Hee; Moreno, Angel; Ross, Brian D.

    2000-04-01

    13C MRS studies at natural abundance and after intravenous 1-13C glucose infusion were performed on a 1.5-T clinical scanner in four subjects. Localization to the occipital cortex was achieved by a surface coil. In natural abundance spectra glucose C3β,5β, myo-inositol, glutamate C1,2,5, glutamine C1,2,5, N-acetyl-aspartate C1-4,Cdbnd O, creatine CH2, CH3, and CCdbnd N, taurine C2,3, bicarbonate HCO-3 were identified. After glucose infusion 13C enrichment of glucose C1α,1β, glutamate C1-4, glutamine C1-4, aspartate C2,3, N-acetyl-aspartate C2,3, lactate C3, alanine C3, and HCO-3 were observed. The observation of 13C enrichment of resonances resonating at >150 ppm is an extension of previously published studies and will provide a more precise determination of metabolic rates and substrate decarboxylation in human brain.

  15. Identification of Biodegradation Pathways in a Multi-Process Phytoremediation System (MPPS) Using Natural Abundance 14C Analysis of PLFA

    NASA Astrophysics Data System (ADS)

    Cowie, B. R.; Greenberg, B. M.; Slater, G. F.

    2008-12-01

    Optimizing remediation of petroleum-contaminated soils requires thorough understanding of the mechanisms and pathways involved in a proposed remediation system. In many engineered and natural attenuation systems, multiple degradation pathways may contribute to observed contaminant mass losses. In this study, biodegradation in the soil microbial community was identified as a major pathway for petroleum hydrocarbon removal in a Multi-Process Phytoremediation System (MPPS) using natural abundance 14C analysis of Phospholipid Fatty Acids (PLFA). In contaminated soils, PLFA were depleted in Δ14C to less than -800‰, directly demonstrating microbial uptake and utilization of petroleum derived carbon (Δ14C = -992‰) during bioremediation. Mass balance indicated that more than 80% of microbial carbon was derived from petroleum hydrocarbons and a maximum of 20% was produced from metabolism of modern carbon sources. In contrast, in a nearby uncontaminated control soil, the microbial community maintained a nearly modern 14C signature, suggesting preferential degradation of more labile, recent carbon. Mass balance using δ13C and Δ14C of soil CO2 demonstrated that mineralization of petroleum carbon contributed 60-65% of soil CO2 at the contaminated site. The remainder was derived from atmospheric (27-30%) and decomposition of non- petroleum natural organic carbon (5-10%). The clean control exhibited substantially lower CO2 concentrations that were derived from atmospheric (55%) and natural organic carbon (45%) sources. This study highlights the value of using multiple carbon isotopes to identify degradation pathways in petroleum- contaminated soils undergoing phytoremediation and the power of natural abundance 14C to detect petroleum metabolism in natural microbial communities.

  16. Quantitative (13)C Solid-State NMR Spectra by Multiple-Contact Cross-polarization for Drug Delivery: From Active Principles to Excipients and Drug Carriers.

    PubMed

    Saïdi, Fadila; Taulelle, Francis; Martineau, Charlotte

    2016-08-01

    In this contribution, we present an analysis of the main parameters influencing the efficiency of the (1)H → (13)C multiple-contact cross-polarization nuclear magnetic resonance (NMR) experiment in the context of solid pharmaceutical materials. Using the optimum experimental conditions, quantitative (13)C NMR spectra are then obtained for porous metal-organic frameworks (potential drug carriers) and for components present in drug formulations (active principle ingredient and excipients, amorphous or crystalline). Finally, we show that mixtures of components can also be quantified with this method and, hence, that it represents an ideal tool for quantification of pharmaceutical formulations by (13)C cross-polarization under magic-angle spinning NMR in the industry as it is robust and easy to set up, much faster than direct (13)C polarization and is efficient for samples at natural abundance. PMID:27372550

  17. Towards a vibrational analysis of spheroidene. Resonance Raman spectroscopy of 13C-labelled spheroidenes in petroleum ether and in the Rhodobacter sphaeroides reaction centre.

    PubMed

    Kok, P; Köhler, J; Groenen, E J; Gebhard, R; van der Hoef, I; Lugtenburg, J; Hoff, A F; Farhoosh, R; Frank, H A

    1994-04-28

    We report resonance Raman spectra of the carotenoid spheroidene and its 14'-13C and 15'-13C substituted analogues in petroleum ether and bound to the reaction centre of Rhodobacter sphaeroides R26. The spectra in petroleum ether correspond to planar all-trans spheroidene while those of the reaction centres are consistent with a nonplanar 15,15'-cis spheroidene. The effect of 13C labelling is largest in the carbon-carbon double-bond stretching region. The 15'-13C substitution of the reaction centre bound spheroidene, however, hardly changes the C=C band as compared to that for the natural abundance spheroidene apart from a new weak band at 1508 cm(-1). This observation has been interpreted as a decoupling of the C15=C15' stretch from the other double-bond stretches in combination with a small intrinsic Raman intensity of this local mode for 15,15'-cis spheroidene. PMID:8167135

  18. Determining the isotopic abundance of a labeled compound by mass spectrometry and how correcting for natural abundance distribution using analogous data from the unlabeled compound leads to a systematic error.

    PubMed

    Schenk, David J; Lockley, William J S; Elmore, Charles S; Hesk, Dave; Roberts, Drew

    2016-04-01

    When the isotopic abundance or specific activity of a labeled compound is determined by mass spectrometry (MS), it is necessary to correct the raw MS data to eliminate ion intensity contributions, which arise from the presence of heavy isotopes at natural abundance (e.g., a typical carbon compound contains ~1.1% (13) C per carbon atom). The most common approach is to employ a correction in which the mass-to-charge distribution of the corresponding unlabeled compound is used to subtract the natural abundance contributions from the raw mass-to-charge distribution pattern of the labeled compound. Following this correction, the residual intensities should be due to the presence of the newly introduced labeled atoms only. However, this will only be the case when the natural abundance mass isotopomer distribution of the unlabeled compound is the same as that of the labeled species. Although this may be a good approximation, it cannot be accurate in all cases. The implications of this approximation for the determination of isotopic abundance and specific activity have been examined in practice. Isotopically mixed stable-atom labeled valine batches were produced, and both these and [(14) C6 ]carbamazepine were analyzed by MS to determine the extent of the error introduced by the approach. Our studies revealed that significant errors are possible for small highly-labeled compounds, such as valine, under some circumstances. In the case with [(14) C6 ]carbamazepine, the errors introduced were minor but could be significant for (14) C-labeled compounds with particular isotopic distributions. This source of systematic error can be minimized, although not eliminated, by the selection of an appropriate isotopic correction pattern or by the use of a program that varies the natural abundance distribution throughout the correction. PMID:26916110

  19. New guidelines for δ13C measurements

    USGS Publications Warehouse

    Coplen, Tyler B.; Brand, Willi A.; Gehre, Matthias; Groning, Manfred; Meijer, Harro A. J.; Toman, Blaza; Verkouteren, R. Michael

    2006-01-01

    Consistency of δ13C measurements can be improved 39−47% by anchoring the δ13C scale with two isotopic reference materials differing substantially in 13C/12C. It is recommended thatδ13C values of both organic and inorganic materials be measured and expressed relative to VPDB (Vienna Peedee belemnite) on a scale normalized by assigning consensus values of −46.6‰ to L-SVEC lithium carbonate and +1.95‰ to NBS 19 calcium carbonate. Uncertainties of other reference material values on this scale are improved by factors up to two or more, and the values of some have been notably shifted:  the δ13C of NBS 22 oil is −30.03%.

  20. Diversity and abundance of phosphonate biosynthetic genes in nature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phosphonates, molecules containing direct C-P bonds, comprise a structurally diverse class of natural products with interesting and useful biological properties. Although their synthesis in protozoa was discovered more than fifty years ago, the extent and diversity of phosphonate production in natur...

  1. Does the Shuram δ13C excursion record Ediacaran oxygenation?

    NASA Astrophysics Data System (ADS)

    Husson, J. M.; Maloof, A. C.; Schoene, B.; Higgins, J. A.

    2013-12-01

    The most negative carbon isotope excursion in Earth history is found in carbonate rocks of the Ediacaran Period (635-542 Ma). Known colloquially as the the 'Shuram' excursion, workers have long noted its tantalizing, broad concordance with the rise of abundant macro-scale fossils in the rock record, variously interpreted as animals, giant protists, macro-algae and lichen, and known as the 'Ediacaran Biota.' Thus, the Shuram excursion has been interpreted by many in the context of a dramatically changing redox state of the Ediacaran oceans - e.g., a result of methane cycling in a low O2 atmosphere, the final destruction of a large pool of recalcitrant dissolved organic carbon (DOC), and the step-wise oxidation of the Ediacaran oceans. More recently, diagenetic interpretations of the Shuram excursion - e.g. sedimentary in-growth of very δ13C depleted authigenic carbonates, meteoric alteration of Ediacaran carbonates, late-stage burial diagenesis - have challenged the various Ediacaran redox models. A rigorous geologic context is required to discriminate between these explanatory models, and determine whether the Shuram excursion can be used to evaluate terminal Neoproterozoic oxygenation. Here, we present chemo-stratigraphic data (δ13C, δ18O, δ44/42Ca and redox sensitive trace element abundances) from 12 measured sections of the Ediacaran-aged Wonoka Formation (Fm.) of South Australia that require a syn-depositional age for the extraordinary range of δ13C values (-12 to +4‰) observed in the formation. In some locations, the Wonoka Fm. is ~700 meters (m) of mixed shelf limestones and siliclastics that record the full 16 ‰ δ13C excursion in a remarkably consistent fashion across 100s of square kilometers of basin area. Fabric-altering diagenesis, where present, occurs at the sub-meter vertical scale, only results in sub-permil offsets in δ13C and cannot be used to explain the full δ13C excursion. In other places, the Wonoka Fm. is host to deep (1 km

  2. In vivo13C spectroscopy in the rat brain using hyperpolarized [1- 13C]pyruvate and [2- 13C]pyruvate

    NASA Astrophysics Data System (ADS)

    Marjańska, Małgorzata; Iltis, Isabelle; Shestov, Alexander A.; Deelchand, Dinesh K.; Nelson, Christopher; Uğurbil, Kâmil; Henry, Pierre-Gilles

    2010-10-01

    The low sensitivity of 13C spectroscopy can be enhanced using dynamic nuclear polarization. Detection of hyperpolarized [1- 13C]pyruvate and its metabolic products has been reported in kidney, liver, and muscle. In this work, the feasibility of measuring 13C signals of hyperpolarized 13C metabolic products in the rat brain in vivo following the injection of hyperpolarized [1- 13C]pyruvate and [2- 13C]pyruvate is investigated. Injection of [2- 13C]pyruvate led to the detection of [2- 13C]lactate, but no other downstream metabolites such as TCA cycle intermediates were detected. Injection of [1- 13C]pyruvate enabled the detection of both [1- 13C]lactate and [ 13C]bicarbonate. A metabolic model was used to fit the hyperpolarized 13C time courses obtained during infusion of [1- 13C]pyruvate and to determine the values of VPDH and VLDH.

  3. Carbon and nitrogen biogeochemistry in the ocean: A study using stable isotope natural abundance

    NASA Technical Reports Server (NTRS)

    Rau, G. H.; Desmarais, David J.

    1985-01-01

    Determining the biogeochemical pathways traveled by carbon and nitrogen in the ocean is fundamental to the understanding of how the ocean participates in the cycling of these elements within the biosphere. Because biological production, metabolism, and respiration can significantly alter the natural abundance of C-13 and N-15, these abundances can provide important information about the nature of these biological processes and their variability in the marine environment. The research initially seeks to characterize the spatial and temporal patterns of stable isotope abundances in organic matter, and to relate these abundances to C and N biogeochemical processes within selected areas of the northeastern Pacific Ocean.

  4. Proton-Enhanced 13C Nuclear Magnetic Resonance of Lipids and Biomembranes

    PubMed Central

    Urbina, Julio; Waugh, J. S.

    1974-01-01

    A recently developed nuclear double resonance technique which permits sensitive detection, together with high resolution, of rare spins in solids or other dipolar-coupled nuclear systems [Pines, Gibby, and Waugh (1973) J. Chem. Phys. 59, 569] has been applied to the study of natural abundance 13C-nuclear magnetic resonance in lipid mesophases and of selectively labeled carbon sites in bacterial membranes. Detailed microscopic information on the molecular organization and phase transitions of the lipid phases and their interaction with ions and other molecules can be obtained from the study of the chemical shift anisotropies and dynamical aspects of the 13C NMR spectra of unsonicated lipid dispersions (liposomes). Experiments are reported which demonstrated the feasibility of quantitatively observing the 13C-nuclear magnetic resonance of specifically labeled sites in unperturbed Escherichia coli membrane vesicles for the study of the physical state of the lipids with the aim of relating it to the known lipid-dependent functional properties of the membranes. PMID:4531036

  5. Measuring (13)C/(15)N chemical shift anisotropy in [(13)C,(15)N] uniformly enriched proteins using CSA amplification.

    PubMed

    Hung, Ivan; Ge, Yuwei; Liu, Xiaoli; Liu, Mali; Li, Conggang; Gan, Zhehong

    2015-11-01

    Extended chemical shift anisotropy amplification (xCSA) is applied for measuring (13)C/(15)N chemical shift anisotropy (CSA) of uniformly labeled proteins under magic-angle spinning (MAS). The amplification sequence consists of a sequence of π-pulses that repetitively interrupt MAS averaging of the CSA interaction. The timing of the pulses is designed to generate amplified spinning sideband manifolds which can be fitted to extract CSA parameters. The (13)C/(13)C homonuclear dipolar interactions are not affected by the π-pulses due to the bilinear nature of the spin operators and are averaged by MAS in the xCSA experiment. These features make the constant evolution-time experiment suitable for measuring CSA of uniformly labeled samples. The incorporation of xCSA with multi-dimensional (13)C/(15)N correlation is demonstrated with a GB1 protein sample as a model system for measuring (13)C/(15)N CSA of all backbone (15)NH, (13)CA and (13)CO sites. PMID:26404770

  6. Resolution enhancement in spectra of natural products dissolved in weakly orienting media with the help of 1H homonuclear dipolar decoupling during acquisition: Application to 1H- 13C dipolar couplings measurements

    NASA Astrophysics Data System (ADS)

    Farjon, Jonathan; Bermel, Wolfgang; Griesinger, Christian

    2006-05-01

    In weakly orienting media such as poly-γ-benzyl- L-glutamate (PBLG) a polymer that forms a chiral liquid crystal in organic solvents, the spectral resolution for embedded molecules is usually poor because of numerous 1H, 1H dipolar couplings that generally broaden proton spectra. Therefore 1H, 13C dipolar couplings are difficult or impossible to measure. Here, we incorporate Flip-Flop decoupling during detection into an HSQC experiment. Flip-Flop removes the 1H, 1H dipolar couplings and scales the chemical shifts of the protons as well as the 1H, 13C dipolar couplings during detection. A resolution gain by a factor 1.5-4.2 and improved signal intensity by an average factor of 1.6-1.7 have been obtained. This technique is demonstrated on (+)-menthol dissolved in a PBLG/CDCl 3 phase.

  7. Transposases are the most abundant, most ubiquitous genes in nature

    PubMed Central

    Aziz, Ramy K.; Breitbart, Mya; Edwards, Robert A.

    2010-01-01

    Genes, like organisms, struggle for existence, and the most successful genes persist and widely disseminate in nature. The unbiased determination of the most successful genes requires access to sequence data from a wide range of phylogenetic taxa and ecosystems, which has finally become achievable thanks to the deluge of genomic and metagenomic sequences. Here, we analyzed 10 million protein-encoding genes and gene tags in sequenced bacterial, archaeal, eukaryotic and viral genomes and metagenomes, and our analysis demonstrates that genes encoding transposases are the most prevalent genes in nature. The finding that these genes, classically considered as selfish genes, outnumber essential or housekeeping genes suggests that they offer selective advantage to the genomes and ecosystems they inhabit, a hypothesis in agreement with an emerging body of literature. Their mobile nature not only promotes dissemination of transposable elements within and between genomes but also leads to mutations and rearrangements that can accelerate biological diversification and—consequently—evolution. By securing their own replication and dissemination, transposases guarantee to thrive so long as nucleic acid-based life forms exist. PMID:20215432

  8. Natural variability in abundance of prevalent soybean proteins.

    PubMed

    Natarajan, Savithiry S

    2010-12-01

    Soybean is an inexpensive source of protein for humans and animals. Genetic modifications (GMO) to soybean have become inevitable on two fronts, both quality and yield will need to improve to meet increasing global demand. To ensure the safety of the crop for consumers it is important to determine the natural variation in seed protein constituents as well as any unintended changes that may occur in the GMO as a result of genetic modification. Understanding the natural variation of seed proteins in wild and cultivated soybeans that have been used in conventional soybean breeding programs is critical for determining unintended protein expression in GMO soybeans. In recent years, proteomic technologies have been used as an effective analytical tool for examining modifications of protein profiles. We have standardized and applied these technologies to determine and quantify the spectrum of proteins present in soybean seed. We used two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), and liquid chromatography mass spectrometry (LC-MS) for the separation, quantification, and identification of different classes of soybean seed proteins. We have observed significant variations in different classes of proteins, including storage, allergen and anti-nutritional protein profiles, between non-GMO cultivated and wild soybean varieties. This information is useful for scientists and regulatory agencies to determine whether the unintended expression of proteins found in transgenic soybean is within the range of natural variation. PMID:20709130

  9. Analysing Groundwater Using the 13C Isotope

    NASA Astrophysics Data System (ADS)

    Awad, Sadek

    The stable isotope of the carbon atom (13C) give information about the type of the mineralisation of the groundwater existing during the water seepage and about the recharge conditions of the groundwater. The concentration of the CO2(aq.) dissolved during the infiltration of the water through the soil's layers has an effect on the mineralisation of this water. The type of the photosynthesis's cycle (C-3 or C-4 carbon cycle) can have a very important role to determine the conditions (closed or open system) of the mineralisation of groundwater. The isotope 13C of the dissolved CO2 in water give us a certain information about the origin and the area of pollution of water. The proportion of the biogenic carbon and its percentage in the mineralisation of groundwater is determined by using the isotope 13C.

  10. States of 13C with abnormal radii

    NASA Astrophysics Data System (ADS)

    Demyanova, A. S.; Ogloblin, A. A.; Danilov, A. N.; Goncharov, S. A.; Belyaeva, T. L.; Sobolev, Yu. G.; Khlebnikov, S. V.; Burtebaev, N.; Trzaska, W.; Heikkinen, P.; Tyurin, G. P.; Janseitov, D.; Gurov, Yu. B.

    2016-05-01

    Differential cross-sections of the elastic and inelastic 13C + α scattering were measured at E(α) = 90 MeV. The root mean-square radii() of 13C nucleus in the states: 8.86 (1/2-), 3.09 (1/2+) and 9.90 (3/2-) MeV were determined by the Modified diffraction model (MDM). The radii of the first two levels are enhanced compared to that of the ground state of 13C, confirming the suggestion that the 8.86 MeV state is an analogue of the Hoyle state in 12C and the 3.09 MeV state has a neutron halo. Some indications to the abnormally small size of the 9.90 MeV state were obtained.

  11. Correction for the 17O interference in δ(13C) measurements when analyzing CO2 with stable isotope mass spectrometry

    USGS Publications Warehouse

    Coplen, Tyler B.; Brand, Willi A.; Assonov, Sergey S.

    2010-01-01

    Measurements of δ(13C) determined on CO2 with an isotope-ratio mass spectrometer (IRMS) must be corrected for the amount of 17O in the CO2. For data consistency, this must be done using identical methods by different laboratories. This report aims at unifying data treatment for CO2 IRMS by proposing (i) a unified set of numerical values, and (ii) a unified correction algorithm, based on a simple, linear approximation formula. Because the oxygen of natural CO2 is derived mostly from the global water pool, it is recommended that a value of 0.528 be employed for the factor λ, which relates differences in 17O and 18O abundances. With the currently accepted N(13C)/N(12C) of 0.011 180(28) in VPDB (Vienna Peedee belemnite) reevaluation of data yields a value of 0.000 393(1) for the oxygen isotope ratio N(17O)/N(16O) of the evolved CO2. The ratio of these quantities, a ratio of isotope ratios, is essential for the 17O abundance correction: [N(17O)/N(16O)]/[N(13C)/N(12C)] = 0.035 16(8). The equation [δ(13C) ≈ 45δVPDB-CO2 + 2 17R/13R (45δVPDB-CO2 – λ46δVPDB-CO2)] closely approximates δ(13C) values with less than 0.010 ‰ deviation for normal oxygen-bearing materials and no more than 0.026 ‰ in extreme cases. Other materials containing oxygen of non-mass-dependent isotope composition require a more specific data treatment. A similar linear approximation is also suggested for δ(18O). The linear approximations are easy to implement in a data spreadsheet, and also help in generating a simplified uncertainty budget.

  12. Direct analysis of δ13C and concentration of dissolved organic carbon (DOC) in environmental samples by TOC-IRMS

    NASA Astrophysics Data System (ADS)

    Kirkels, Frédérique; Cerli, Chiara; Federherr, Eugen; Kalbitz, Karsten

    2014-05-01

    Dissolved organic carbon (DOC) plays an important role in carbon cycling in terrestrial and aquatic systems. Stable isotope analysis (delta 13C) of DOC could provide valuable insights in its origin, fluxes and environmental fate. Precise and routine analysis of delta 13C and DOC concentration are therefore highly desirable. A promising, new system has been developed for this purpose, linking a high-temperature combustion TOC analyzer trough an interface with a continuous flow isotope ratio mass spectrometer (Elementar group, Hanau, Germany). This TOC-IRMS system enables simultaneous stable isotope (bulk delta 13C) and concentration analysis of DOC, with high oxidation efficiency by high-temperature combustion for complex mixtures as natural DOC. To give delta 13C analysis by TOC-IRMS the necessary impulse for broad-scale application, we present a detailed evaluation of its analytical performance for realistic and challenging conditions inclusive low DOC concentrations and environmental samples. High precision (standard deviation, SD predominantly < 0.15 permil) and accuracy (R2 = 0.9997, i.e. comparison TOC-IRMS and conventional EA-IRMS) were achieved by TOC-IRMS for a broad diversity of DOC solutions. This precision is comparable or even slightly better than that typically reported for EA-IRMS systems, and improves previous techniques for δ13C analysis of DOC. Simultaneously, very good precision was obtained for DOC concentration measurements. Assessment of natural abundance and slightly 13C enriched DOC, a wide range of concentrations (0.2-150 mgC/L) and injection volumes (0.05-3 ml), demonstrated good analytical performance with negligible memory effects, no concentration/volume effects and a wide linearity. Low DOC concentrations (< 2 mgC/L), were correctly analyzed without any pre-concentration. Moreover, TOC-IRMS was successfully applied to analyze DOC from diverse terrestrial, freshwater and marine environments (SD < 0.23 permil). In summary, the TOC

  13. Food Resources of Stream Macronivertebrates Determined by Natural-Abundance stable C and N Isotopes and a 15N Tracer Addition

    SciTech Connect

    Mulholland, P. J.

    2000-01-01

    Trophic relationships were examined using natural-abundance {sup 13}C and {sup 15}N analyses and a {sup 15}N-tracer addition experiment in Walker Branch, a 1st-order forested stream in eastern Tennessee. In the {sup 15}N-tracer addition experiment, we added {sup 15}NH{sub 4} to stream water over a 6-wk period in early spring, and measured {sup 15}N:{sup 14}N ratios in different taxa and biomass compartments over distance and time. Samples collected from a station upstream from the {sup 15}N addition provided data on natural-abundance {sup 13}C:{sup 12}C and {sup 15}N:{sup 14}N ratios. The natural-abundance {sup 15}N analysis proved to be of limited value in identifying food resources of macroinvertebrates because {sup 15}N values were not greatly different among food resources. In general, the natural-abundance stable isotope approach was most useful for determining whether epilithon or detritus were important food resources for organisms that may use both (e.g., the snail Elimia clavaeformis), and to provide corroborative evidence of food resources of taxa for which the {sup 15}N tracer results were not definitive. The {sup 15}N tracer results showed that the mayflies Stenonema spp. and Baetis spp. assimilated primarily epilithon, although Baetis appeared to assimilate a portion of the epilithon (e.g., algal cells) with more rapid N turnover than the bulk pool sampled. Although Elimia did not reach isotopic equilibrium during the tracer experiment, application of a N-turnover model to the field data suggested that it assimilated a combination of epilithon and detritus. The amphipod Gammarus minus appeared to depend mostly on fine benthic organic matter (FBOM), and the coleopteran Anchytarsus bicolor on epixylon. The caddisfly Diplectrona modesta appeared to assimilate primarily a fast N-turnover portion of the FBOM pool, and Simuliidae a fast N-turnover component of the suspended particulate organic matter pool rather than the bulk pool sampled. Together, the

  14. Studies of minute quantities of natural abundance molecules using 2D heteronuclear correlation spectroscopy under 100kHz MAS

    DOE PAGESBeta

    Nishiyama, Y.; Kobayashi, T.; Malon, M.; Singappuli-Arachchige, D.; Slowing, I. I.; Pruski, M.

    2015-02-16

    Two-dimensional 1H{13C} heteronuclear correlation solid-state NMR spectra of naturally abundant solid materials are presented, acquired using the 0.75-mm magic angle spinning (MAS) probe at spinning rates up to 100 kHz. In spite of the miniscule sample volume (290 nL), high-quality HSQC-type spectra of bulk samples as well as surface-bound molecules can be obtained within hours of experimental time. The experiments are compared with those carried out at 40 kHz MAS using a 1.6-mm probe, which offered higher overall sensitivity due to a larger rotor volume. The benefits of ultrafast MAS in such experiments include superior resolution in 1H dimensionmore » without resorting to 1H–1H homonuclear RF decoupling, easy optimization, and applicability to mass-limited samples. As a result, the HMQC spectra of surface-bound species can be also acquired under 100 kHz MAS, although the dephasing of transverse magnetization has significant effect on the efficiency transfer under MAS alone.« less

  15. Modification of local electronic state by BEDT-STF doping to κ -(BEDT-TTF)2Cu[N (CN ) 2]Br salt studied by 13C NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Ihara, Y.; Kawamoto, A.

    2016-03-01

    We present the results of site-selective 13C NMR spectroscopy on an organic superconductor κ -(BEDT-TTF)2Cu[N (CN ) 2]Br (κ -Br) doped with BEDT-STF molecules. We reveal microscopically the modulation of the local electronic state caused by the BEDT-STF doping from the 13C NMR measurement on two types of samples, which are 13C enriched κ -Br doped with naturally abundant BEDT-STF molecules, and natural κ -Br doped with 13C enriched BEDT-STF molecules. The results of the nuclear spin-lattice relaxation rate 1 /T1 measured both in the normal and superconducting state suggest that the potential disorder at the BEDT-STF sites scatters antiferromagnetic interaction and superconducting Cooper pairs.

  16. Accurate quantification of sphingosine-1-phosphate in normal and Fabry disease plasma, cells and tissues by LC-MS/MS with (13)C-encoded natural S1P as internal standard.

    PubMed

    Mirzaian, Mina; Wisse, Patrick; Ferraz, Maria J; Marques, André R A; Gabriel, Tanit L; van Roomen, Cindy P A A; Ottenhoff, Roelof; van Eijk, Marco; Codée, Jeroen D C; van der Marel, Gijsbert A; Overkleeft, Herman S; Aerts, Johannes M

    2016-08-01

    We developed a mass spectrometric procedure to quantify sphingosine-1-phosphate (S1P) in biological materials. The use of newly synthesized (13)C5 C18-S1P and commercial C17-S1P as internal standards rendered very similar results with respect to linearity, limit of detection and limit of quantitation. Caution is warranted with determination of plasma S1P levels. Earlier it was reported that S1P is elevated in plasma of Fabry disease patients. We investigated this with the improved quantification. No clear conclusion could be drawn for patient plasma samples given the lack of uniformity of blood collection and plasma preparation. To still obtain insight, plasma and tissues were identically collected from α-galactosidase A deficient Fabry mice and matched control animals. No significant difference was observed in plasma S1P levels. A significant 2.3 fold increase was observed in kidney of Fabry mice, but not in liver and heart. Comparative analysis of S1P in cultured fibroblasts from normal subjects and classically affected Fabry disease males revealed no significant difference. In conclusion, accurate quantification of S1P in biological materials is feasible by mass spectrometry using the internal standards (13)C5 C18-S1P or C17-S1P. Significant local increases of S1P in the kidney might occur in Fabry disease as suggested by the mouse model. PMID:27221202

  17. Synthesis Of [2h, 13c] And [2h3, 13c]Methyl Aryl Sulfides

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2004-03-30

    The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2,.sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfides wherein the .sup.13 C methyl group attached to the sulfur of the sulfide includes exactly one, two or three deuterium atoms. The present invention is also directed to the labeled compounds of [.sup.2 H.sub.1, .sup.13 C]methyl iodide and [.sup.2 H.sub.2, .sup.13 C]methyl iodide.

  18. Evaluating microbial carbon sources in Athabasca oil sands tailings ponds using natural abundance stable and radiocarbon isotopes

    NASA Astrophysics Data System (ADS)

    Ahad, J. M.; Pakdel, H.

    2013-12-01

    Natural abundance stable (δ13C) and radiocarbon (Δ14C) isotopes of phospholipid fatty acids (PLFAs) were used to evaluate the carbon sources utilized by the active microbial populations in surface sediments from Athabasca oil sands tailings ponds. The absence of algal-specific PLFAs at three of the four sites investigated, in conjunction with δ13C signatures for PLFAs that were generally within ~3‰ of that reported for oil sands bitumen (~ -30‰), indicated that the microbial communities growing on petroleum constituents were dominated by aerobic heterotrophs. The Δ14C values of PLFAs ranged from -906 to -586‰ and pointed to a significant uptake of fossil carbon (up to ~90% of microbial carbon derived from petroleum), particularly in PLFAs (e.g., cy17:0 and cy19:0) often associated with petroleum hydrocarbon degrading bacteria. The comparatively higher levels of 14C in other, less specific PLFAs (e.g., 16:0) indicated the preferential uptake of younger organic matter by the general microbial population (~50-80% of microbial carbon derived from petroleum). Since the main carbon pools in tailings sediment were essentially 'radiocarbon dead' (i.e., no detectable 14C), the principal source for this modern carbon is considered to be the Athabasca River, which provides the bulk of the water used in the bitumen extraction process. The preferential uptake of the minor amount of young and presumably more biodegradable material present in systems otherwise dominated by recalcitrant petroleum constituents has important implications for remediation strategies. On the one hand, it implies that mining-related organic contaminants could persist in the environment long after tailings pond reclamation has begun. Alternatively, it may be that the young, labile organic matter provided by the Athabasca River plays an important role in stimulating or supporting the microbial utilization of petroleum carbon in oil sands tailings ponds via co-metabolism or priming processes

  19. Performance evaluation of quantitative adiabatic (13)C NMR pulse sequences for site-specific isotopic measurements.

    PubMed

    Thibaudeau, Christophe; Remaud, Gérald; Silvestre, Virginie; Akoka, Serge

    2010-07-01

    (2)H/(1)H and (13)C/(12)C site-specific isotope ratios determined by NMR spectroscopy may be used to discriminate pharmaceutically active ingredients based on the synthetic process used in production. Extending the Site-specific Natural Isotope Fractionation NMR (SNIF-NMR) method to (13)C is highly beneficial for complex organic molecules when measurements of (2)H/(1)H ratios lead to poorly defined molecular fingerprints. The current NMR methodology to determine (13)C/(12)C site-specific isotope ratios suffers from poor sensitivity and long experimental times. In this work, several NMR pulse sequences based on polarization transfer were evaluated and optimized to measure precise quantitative (13)C NMR spectra within a short time. Adiabatic 180 degrees (1)H and (13)C pulses were incorporated into distortionless enhancement by polarization transfer (DEPT) and refocused insensitive nuclei enhanced by polarization transfer (INEPT) to minimize the influence of 180 degrees pulse imperfections and of off-resonance effects on the precision of the measured (13)C peak areas. The adiabatic DEPT sequence was applied to draw up a precise site-specific (13)C isotope profile of ibuprofen. A modified heteronuclear cross-polarization (HCP) experiment featuring (1)H and (13)C spin-locks with adiabatic 180 degrees pulses is also introduced. This sequence enables efficient magnetization transfer across a wide (13)C frequency range although not enough for an application in quantitative (13)C isotopic analysis. PMID:20527737

  20. Use of n-hexadecane-1,2-{sup 13}C to understand the cracking mechanism and kinetics of normal alkanes in crude oils

    SciTech Connect

    Burnham, A.K.; Gregg, H.R.; Ward, R.L.; Knauss, K.G.

    1995-12-01

    Adjacent {sup 13}C atoms are rare in natural abundance, so their use as isotopic tracers provides a sensitive and selective method to follow reaction pathways of specific molecules in complex reaction matrices. N-hexadecane-1,2-{sup 13}C added to neat hexedecane and three distinctly different crude oils has enabled us to outline similarities and differences in the high-pressure alkane cracking reactions in these different matrices, with and without added water. Reaction progress was monitored by GC-MS (P+2) and {sup 13}C NMR ({open_quotes}INADEQUATE{close_quotes} pulse sequence). The overall cracking rate is 60% slower in real oils, apparently because more labile sources in the crude oil preferentially donate hydrogen to the alkyl radicals. The oil matrices also inhibit the formation of larger branched alkanes by alkyl addition of alkenes.

  1. Accurate determinations of one-bond 13C-13C couplings in 13C-labeled carbohydrates

    NASA Astrophysics Data System (ADS)

    Azurmendi, Hugo F.; Freedberg, Darón I.

    2013-03-01

    Carbon plays a central role in the molecular architecture of carbohydrates, yet the availability of accurate methods for 1DCC determination has not been sufficiently explored, despite the importance that such data could play in structural studies of oligo- and polysaccharides. Existing methods require fitting intensity ratios of cross- to diagonal-peaks as a function of the constant-time (CT) in CT-COSY experiments, while other methods utilize measurement of peak separation. The former strategies suffer from complications due to peak overlap, primarily in regions close to the diagonal, while the latter strategies are negatively impacted by the common occurrence of strong coupling in sugars, which requires a reliable assessment of their influence in the context of RDC determination. We detail a 13C-13C CT-COSY method that combines a variation in the CT processed with diagonal filtering to yield 1JCC and RDCs. The strategy, which relies solely on cross-peak intensity modulation, is inspired in the cross-peak nulling method used for JHH determinations, but adapted and extended to applications where, like in sugars, large one-bond 13C-13C couplings coexist with relatively small long-range couplings. Because diagonal peaks are not utilized, overlap problems are greatly alleviated. Thus, one-bond couplings can be determined from different cross-peaks as either active or passive coupling. This results in increased accuracy when more than one determination is available, and in more opportunities to measure a specific coupling in the presence of severe overlap. In addition, we evaluate the influence of strong couplings on the determination of RDCs by computer simulations. We show that individual scalar couplings are notably affected by the presence of strong couplings but, at least for the simple cases studied, the obtained RDC values for use in structural calculations were not, because the errors introduced by strong couplings for the isotropic and oriented phases are very

  2. A Computational Framework for High-Throughput Isotopic Natural Abundance Correction of Omics-Level Ultra-High Resolution FT-MS Datasets

    PubMed Central

    Carreer, William J.; Flight, Robert M.; Moseley, Hunter N. B.

    2013-01-01

    New metabolomics applications of ultra-high resolution and accuracy mass spectrometry can provide thousands of detectable isotopologues, with the number of potentially detectable isotopologues increasing exponentially with the number of stable isotopes used in newer isotope tracing methods like stable isotope-resolved metabolomics (SIRM) experiments. This huge increase in usable data requires software capable of correcting the large number of isotopologue peaks resulting from SIRM experiments in a timely manner. We describe the design of a new algorithm and software system capable of handling these high volumes of data, while including quality control methods for maintaining data quality. We validate this new algorithm against a previous single isotope correction algorithm in a two-step cross-validation. Next, we demonstrate the algorithm and correct for the effects of natural abundance for both 13C and 15N isotopes on a set of raw isotopologue intensities of UDP-N-acetyl-D-glucosamine derived from a 13C/15N-tracing experiment. Finally, we demonstrate the algorithm on a full omics-level dataset. PMID:24404440

  3. The physical state of osmoregulatory solutes in unicellular algae. A natural-abundance carbon-13 nuclear-magnetic-resonance relaxation study.

    PubMed Central

    Norton, R S; MacKay, M A; Borowitzka, L J

    1982-01-01

    Natural-abundance 13C n.m.r. spin-lattice relaxation-time measurements have been carried out on intact cells of the unicellular blue--green alga Synechococcus sp. and the unicellular green alga Dunaliella salina, with the aim of characterizing the environments of the organic osmoregulatory solutes in these salt-tolerant organisms. In Synechococcus sp., all of the major organic osmoregulatory solute, 2-O-alpha-D-glucopyranosylglycerol, is visible in spectra of intact cells. Its rotational motion in the cell is slower by a factor of approx. 2.4 than in aqueous solution, but the molecule is still freely mobile and therefore able to contribute to the osmotic balance. In D. salina, only about 60% of the osmoregulatory solute glycerol is visible in spectra of intact cells. The rotational mobility of this observable fraction is approximately half that found in aqueous solution, but the data also indicate that there is a significant concentration of some paramagnetic species in D. salina which contributes to the overall spin-lattice relaxation of the glycerol carbon atoms. The non-observable fraction, which must correspond to glycerol molecules that have very broad 13C resonances and that are in slow exchange with bulk glycerol, has not been properly characterized as yet, but may represent glycerol in the chloroplast. The implications of these findings in relation to the physical state of the cytoplasm and the mechanism of osmoregulation in these cells are discussed. PMID:6807296

  4. The use of natural abundance carbon-13 to identify and quantify sources of emitted carbon dioxide in a calcareous southern Ontario Luvisolic soil

    NASA Astrophysics Data System (ADS)

    Wilton, Meaghan

    Three studies Were conducted at the Elora Research Station (ERS) on a Luvisolic soil to investigate the soil inorganic carbon (SIC) and soil organic carbon (SOC) components contributing to the CO2 flux (FC) using natural 13C abundance. SIC contributed to the FC in intact soil incubations. Soil disruption exacerbated the release of CO2 from both pedogenic and lithogenic carbonates. Field and laboratory techniques to obtain the delta13C of respired CO2 (delta13CR) were compared. Short-term deployment of non flow-through non steady-state chambers and the use of the simple two-ended mass balance approach to derive delta 13CR were found acceptable to apply to the ERS site. The delta13CR from a corn field at ERS with a history of multiple C4 and C3 crop rotations was partitioned into SIC and SOC components using two approaches. Root respiration contributed 2% - 64% and carbonates contribute up to 20% to the FC.

  5. Are δ13C values of n-alkanes affected by atmospheric CO2 concentrations? Results from a free-air CO2 enrichment (FACE) experiment.

    NASA Astrophysics Data System (ADS)

    Sandquist, D. R.; Williams, D. G.; Shuman, B. N.; Kim, S.; Chen, J.; Macdonald, C.

    2015-12-01

    Compound-specific carbon isotope (δ13C) analyses of leaf waxes (i.e., n-alkanes) can be linked to large-scale shifts in vegetation, such as dominant taxa, functional types, life-forms and photosynthetic pathways that are usually coupled with environmental changes in climate. However using these δ13C values to interpret finer-scale ecosystem properties, including climate attributes such as CO2 concentrations, is difficult owing to uncertainty in the magnitude of internal biosynthetic fractionations that determine the δ13C of waxes relative to that of bulk leaf material. We investigated the composition, abundance and δ13C of n-alkanes in the aboveground biomass of a C4 grass and a C3 grass exposed to experimentally controlled CO2 at ambient [490ppm] and elevated [630ppm] levels within natural grassland in Wyoming. The δ13C values of bulk tissues were predictably different based on the C3 and C4 photosynthetic pathways, but the difference between bulk tissue and n-alkanes (ɛlipid), for both C29 and C31, was consistently greater in the C4 grass. The magnitudes of these ɛlipid values were large (- 7‰ to -15‰) relative to those found in most other studies. CO2 concentration of the growing environment also had a significant effect on n-alkane δ13C values, with consistently higher values of ~ 2‰ under elevated CO2 found in both species and in both a wet and a dry year. These results underscore the importance of recognizing potential abiotic effects on leaf wax δ13C values, in addition to the biotic drivers their variation, when interpreting climate from leaf-wax biomarkers of terrestrial ecosystems.

  6. An efficient NMR method for the characterisation of 14N sites through indirect 13C detection

    PubMed Central

    Jarvis, James A.; Haies, Ibraheem M.

    2013-01-01

    Nitrogen is one of the most abundant elements and plays a key role in the chemistry of biological systems. Despite its widespread distribution, the study of the naturally occurring isotope of nitrogen, 14N (99.6%), has been relatively limited as it is a spin-1 nucleus that typically exhibits a large quadrupolar interaction. Accordingly, most studies of nitrogen sites in biomolecules have been performed on samples enriched with 15N, limiting the application of NMR to samples which can be isotopically enriched. This precludes the analysis of naturally occurring samples and results in the loss of the wealth of structural and dynamic information that the quadrupolar interaction can provide. Recently, several experimental approaches have been developed to characterize 14N sites through their interaction with neighboring ‘spy’ nuclei. Here we describe a novel version of these experiments whereby coherence between the 14N site and the spy nucleus is mediated by the application of a moderate rf field to the 14N. The resulting 13C/14N spectra show good sensitivity on natural abundance and labeled materials; whilst the 14N lineshapes permit the quantitative analysis of the quadrupolar interaction. PMID:23589073

  7. Optoacoustic 13C-breath test analyzer

    NASA Astrophysics Data System (ADS)

    Harde, Hermann; Helmrich, Günther; Wolff, Marcus

    2010-02-01

    The composition and concentration of exhaled volatile gases reflects the physical ability of a patient. Therefore, a breath analysis allows to recognize an infectious disease in an organ or even to identify a tumor. One of the most prominent breath tests is the 13C-urea-breath test, applied to ascertain the presence of the bacterium helicobacter pylori in the stomach wall as an indication of a gastric ulcer. In this contribution we present a new optical analyzer that employs a compact and simple set-up based on photoacoustic spectroscopy. It consists of two identical photoacoustic cells containing two breath samples, one taken before and one after capturing an isotope-marked substrate, where the most common isotope 12C is replaced to a large extent by 13C. The analyzer measures simultaneously the relative CO2 isotopologue concentrations in both samples by exciting the molecules on specially selected absorption lines with a semiconductor laser operating at a wavelength of 2.744 μm. For a reliable diagnosis changes of the 13CO2 concentration of 1% in the exhaled breath have to be detected at a concentration level of this isotope in the breath of about 500 ppm.

  8. THE GALACTIC R CORONAE BOREALIS STARS: THE C{sub 2} SWAN BANDS, THE CARBON PROBLEM, AND THE {sup 12}C/{sup 13}C RATIO

    SciTech Connect

    Hema, B. P.; Pandey, Gajendra; Lambert, David L. E-mail: pandey@iiap.res.in

    2012-03-10

    Observed spectra of R Coronae Borealis (RCB) and hydrogen-deficient carbon (HdC) stars are analyzed by synthesizing the C{sub 2} Swan bands (1, 0), (0, 0), and (0, 1) using our detailed line list and the Uppsala model atmospheres. The (0, 1) and (0, 0) C{sub 2} bands are used to derive the {sup 12}C abundance, and the (1, 0) {sup 12}C{sup 13}C band to determine the {sup 12}C/{sup 13}C ratios. The carbon abundance derived from the C{sub 2} Swan bands is about the same for the adopted models constructed with different carbon abundances over the range 8.5 (C/He = 0.1%) to 10.5 (C/He = 10%). Carbon abundances derived from C I lines are about a factor of four lower than the carbon abundance of the adopted model atmosphere over the same C/He interval, as reported by Asplund et al., who dubbed the mismatch between adopted and derived C abundance as the 'carbon problem'. In principle, the carbon abundances obtained from C{sub 2} Swan bands and that assumed for the model atmosphere can be equated for a particular choice of C/He that varies from star to star. Then, the carbon problem for C{sub 2} bands is eliminated. However, such C/He ratios are in general less than those of the extreme helium stars, the seemingly natural relatives to the RCB and HdC stars. A more likely solution to the C{sub 2} carbon problem may lie in a modification of the model atmosphere's temperature structure. The derived carbon abundances and the {sup 12}C/{sup 13}C ratios are discussed in light of the double degenerate and the final flash scenarios.

  9. Liquid and gas chromatography coupled to isotope ratio mass spectrometry for the determination of 13C-valine isotopic ratios in complex biological samples.

    PubMed

    Godin, Jean-Philippe; Breuillé, Denis; Obled, Christiane; Papet, Isabelle; Schierbeek, Henk; Hopfgartner, Gérard; Fay, Laurent-Bernard

    2008-10-01

    On-line gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) is commonly used to measure isotopic ratios at natural abundance as well as for tracer studies in nutritional and medical research. However, high-precision (13)C isotopic enrichment can also be measured by liquid chromatography-isotope ratio mass spectrometry (LC-IRMS). Indeed, LC-IRMS can be used, as shown by the new method reported here, to obtain a baseline separation and to measure (13)C isotopic enrichment of underivatised amino acids (Asp, Thr-Ser, Glu, Pro, Gly, Ala, Cys and Val). In case of Val, at natural abundance, the SD(delta(13)C) reported with this method was found to be below 1 per thousand . Another key feature of the new LC-IRMS method reported in this paper is the comparison of the LC-IRMS approach with the conventional GC-C-IRMS determination. To perform this comparative study, isotopic enrichments were measured from underivatised Val and its N(O, S)-ethoxycarbonyl ethyl ester derivative. Between 0.0 and 1.0 molar percent excess (MPE) (delta(13)C= -12.3 to 150.8 per thousand), the calculated root-mean-square (rms) of SD was 0.38 and 0.46 per thousand and the calculated rms of accuracy was 0.023 and 0.005 MPE, respectively, for GC-C-IRMS and LC-IRMS. Both systems measured accurately low isotopic enrichments (0.002 atom percent excess (APE)) with an SD (APE) of 0.0004. To correlate the relative (delta(13)C) and absolute (atom%, APE and MPE) isotopic enrichment of Val measured by the GC-C-IRMS and LC-IRMS devices, mathematical equations showing the slope and intercept of the curves were established and validated with experimental data between 0.0 to 2.3 MPE. Finally, both GC-C-IRMS and LC-IRMS instruments were also used to assess isotopic enrichment of protein-bound (13)C-Val in tibial epiphysis in a tracer study performed in rats. Isotopic enrichments measured by LC-IRMS and GC-C-IRMS were not statistically different (p>0.05). The results of this work indicate that

  10. Changes in Natural Abundance Carbon Stable isotopes of Human Blood and Saliva After 24 Days of Controlled Carbohydrate Supplementation

    NASA Astrophysics Data System (ADS)

    Kraft, R. A.; Jahren, A. H.; Baer, D. J.; Caballero, B.

    2008-12-01

    the δ13C value of their blood and saliva relative to baseline: blood clot was enriched by 0.27‰; blood serum by 0.50‰ and saliva by 1.12‰. We believe this overall enrichment resulted from a 13C-enriched bulk diet (δ13C = - 20.42‰) relative to the subjects free-living diet. Evidence for this derives from inspection of foods within the bulk diet provided, compared to published profiles of the typical American diet. We will discuss possible complicating factors, such as differential absorption and metabolism of the supplements according to solubility and caloric value. These results are encouraging for the development of a δ13C blood serum biomarker that, in the company of other tests, could be used to indicate a change in carbohydrate intake. Bray, G.A., Nielsen, S.J. and Popkin, B.M., 2004. Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity. American Journal of Clinical Nutrition, 79: 537-543. Havel, P.J., 2005. Dietary fructose: Implications for dysregulation of energy homeostasis and lipid/carbohydrate metabolism. Nutrition Reviews, 63(5): 133-157. Tilman D., 1998. The greening of the green revolution. Nature, 396:211-212.

  11. 13c Measurements On Air of Small Ice Samples

    NASA Astrophysics Data System (ADS)

    Eyer, M.; Leuenberger, M.

    We have developed a new method for 13C analysis for very small air amounts of less than 0.5 cc STP, corresponding to less than 10 gram of ice. It is based on the needle-crasher technique, which we routinely use for CO2 concentration measurements by infrared laser absorption. The extracted air is slowly expanded into a large volume through a water trap held at ­100°C. This sampled air is then carried by a high helium flux through a modified Precon system of Thermo-Finnigan to separate CO2 from the air and to inject the pure CO2 gas in a low helium stream via an open split device to a Delta Plus XL mass spectrometer. The overall precision based on replicates of standard air is significantly better than 0.1 for a single analysis and is further improved by a triplicate measurement of the same sample through a specially designed gas splitter. We have used this new method for investigations on polar ice cores. The 13C measurements are important for climate reconstructions, e.g. to reconstruct the evolution and its variability in the terrestrial and oceanic carbon sinks and to identify natural variations in the marine carbon cycle. During the industrialization atmospheric 13C decreased by about -2, mainly due to the anthropogenic release of biogenic CO2 by fossil fuel burning. Reconstructions of carbon and oxygen cycles of Joos at al. [1999] using a double deconvolution method show that between 1930 and 1950 the net terrestrial release is changing to a net terrestrial uptake of CO2. A highly resolved 13C dataset of this time window would replenish the documentation of this behaviour. Further, it would be interesting to compare such data with O2/N2 measurements, known as an other partitioning tool for carbon sources and sinks. At the EGS 2002 we will present a highly resolved 13C record from Antarctic ice covering this time period.

  12. Towards hyperpolarized 13C-succinate imaging of brain cancer

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Pratip; Chekmenev, Eduard Y.; Perman, William H.; Harris, Kent C.; Lin, Alexander P.; Norton, Valerie A.; Tan, Chou T.; Ross, Brian D.; Weitekamp, Daniel P.

    2007-05-01

    We describe a novel 13C enriched precursor molecule, sodium 1- 13C acetylenedicarboxylate, which after hydrogenation by PASADENA (Parahydrogen and Synthesis Allows Dramatically Enhanced Nuclear Alignment) under controlled experimental conditions, becomes hyperpolarized 13C sodium succinate. Fast in vivo 3D FIESTA MR imaging demonstrated that, following carotid arterial injection, the hyperpolarized 13C-succinate appeared in the head and cerebral circulation of normal and tumor-bearing rats. At this time, no in vivo hyperpolarized signal has been localized to normal brain or brain tumor. On the other hand, ex vivo samples of brain harvested from rats bearing a 9L brain tumor, 1 h or more following in vivo carotid injection of hyperpolarized 13C sodium succinate, contained significant concentrations of the injected substrate, 13C sodium succinate, together with 13C maleate and succinate metabolites 1- 13C-glutamate, 5- 13C-glutamate, 1- 13C-glutamine and 5- 13C-glutamine. The 13C substrates and products were below the limits of NMR detection in ex vivo samples of normal brain consistent with an intact blood-brain barrier. These ex vivo results indicate that hyperpolarized 13C sodium succinate may become a useful tool for rapid in vivo identification of brain tumors, providing novel biomarkers in 13C MR spectral-spatial images.

  13. Unified and isomer-specific NMR metabolomics database for the accurate analysis of (13)C-(1)H HSQC spectra.

    PubMed

    Bingol, Kerem; Li, Da-Wei; Bruschweiler-Li, Lei; Cabrera, Oscar A; Megraw, Timothy; Zhang, Fengli; Brüschweiler, Rafael

    2015-02-20

    A new metabolomics database and query algorithm for the analysis of (13)C-(1)H HSQC spectra is introduced, which unifies NMR spectroscopic information on 555 metabolites from both the Biological Magnetic Resonance Data Bank (BMRB) and Human Metabolome Database (HMDB). The new database, termed Complex Mixture Analysis by NMR (COLMAR) (13)C-(1)H HSQC database, can be queried via an interactive, easy to use web interface at http://spin.ccic.ohio-state.edu/index.php/hsqc/index . Our new HSQC database separately treats slowly exchanging isomers that belong to the same metabolite, which permits improved query in cases where lowly populated isomers are below the HSQC detection limit. The performance of our new database and query web server compares favorably with the one of existing web servers, especially for spectra of samples of high complexity, including metabolite mixtures from the model organisms Drosophila melanogaster and Escherichia coli. For such samples, our web server has on average a 37% higher accuracy (true positive rate) and a 82% lower false positive rate, which makes it a useful tool for the rapid and accurate identification of metabolites from (13)C-(1)H HSQC spectra at natural abundance. This information can be combined and validated with NMR data from 2D TOCSY-type spectra that provide connectivity information not present in HSQC spectra. PMID:25333826

  14. Natural abundance 17O DNP two-dimensional and surface-enhanced NMR spectroscopy

    DOE PAGESBeta

    Perras, Frédéric A.; Kobayashi, Takeshi; Pruski, Marek

    2015-06-22

    Due to its extremely low natural abundance and quadrupolar nature, the 17O nuclide is very rarely used for spectroscopic investigation of solids by NMR without isotope enrichment. Additionally, the applicability of dynamic nuclear polarization (DNP), which leads to sensitivity enhancements of 2 orders of magnitude, to 17O is wrought with challenges due to the lack of spin diffusion and low polarization transfer efficiency from 1H. Here, we demonstrate new DNP-based measurements that extend 17O solid-state NMR beyond its current capabilities. The use of the PRESTO technique instead of conventional 1H–17O cross-polarization greatly improves the sensitivity and enables the facile measurementmore » of undistorted line shapes and two-dimensional 1H–17O HETCOR NMR spectra as well as accurate internuclear distance measurements at natural abundance. This was applied for distinguishing hydrogen-bonded and lone 17O sites on the surface of silica gel; the one-dimensional spectrum of which could not be used to extract such detail. As a result, this greatly enhanced sensitivity has enabled, for the first time, the detection of surface hydroxyl sites on mesoporous silica at natural abundance, thereby extending the concept of DNP surface-enhanced NMR spectroscopy to the 17O nuclide.« less

  15. Temporal δ13C records from bottlenose dolphins (Tursiops truncatus) reflect variation in foraging location and global carbon cycling

    NASA Astrophysics Data System (ADS)

    Rossman, S. L.; Barros, N. B.; Ostrom, P. H.; Gandhi, H.; Wells, R. S.

    2010-12-01

    With four decades of data on a population of bottlenose dolphins (Tursiops truncatus) resident to Sarasota Bay (SB), The Sarasota Dolphin Research Program offers an unparalleled platform for ground-truthing stable isotope data and exploring bottlenose dolphin ecology in a natural setting. We explored carbon isotope value fidelity to habitat utilization by comparing δ13C data from whole teeth and muscle to the individual dolphin's proclivity towards foraging in seagrass beds based on observational data. We then examined variation in habitat use based on temporal isotope records. Whole tooth protein isotope values do not show a significant correlation with the observed percentage of foraging in seagrass habitat. In contrast, δ13C values from muscle showed a significant positive relationship with the observational data. Differences in the degree of tissue turn over may account for this distinction between tooth and muscle. Dolphin teeth consist of annually deposited layers that are inert once formed. Thus, the isotopic composition of protein in annuli reflect foraging at the time of deposition. In addition to incorporating variation associated with differences in foraging over the lifetime of the individual, whole tooth isotope values are confounded because a disproportionate amount of tooth protein derives from the first few years of life. Given the turnover time of muscle tissue, isotope values reflect diet over the past several months. From 1991 to 2008, muscle δ13C values showed a significant decline, -13.5‰ to -15.1‰.This time period encompasses a state wide net fishing ban (1995) however other factors such as a series of red tide harmful algal blooms, a decline in predators, increases in shallow water boat traffic and an increase in string ray abundance may also contribute to the temporal isotope trend. To examine changes in dolphin foraging habitat further back in time we analyzed the tip of crown of the tooth which records the isotopic signal from the

  16. Synthesis Of 2h- And 13c-Substituted Dithanes

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2004-05-04

    The present invention is directed to labeled compounds, [2-.sup.13 C]dithane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to processes of preparing [2-.sup.13 C]dithane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to labeled compounds, e.g., [.sup.2 H.sub.1-2, .sup.13 C]methanol (arylthio)-, acetates wherein the .sup.13 C atom is directly bonded to exactly one or two deuterium atoms.

  17. Synthesis of 2H- and 13C-substituted dithanes

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.

    2003-01-01

    The present invention is directed to labeled compounds, [2-.sup.13 C]dithiane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to processes of preparing [2-.sup.13 C]dithiane wherein the .sup.13 C atom is directly bonded to one or two deuterium atoms. The present invention is also directed to labeled compounds, e.g., [.sup.2 H.sub.1-2, .sup.13 C]methanol (arylthio)-, acetates wherein the .sup.13 C atom is directly bonded to exactly one or two deuterium atoms.

  18. Dipolar-coupling-mediated total correlation spectroscopy in solid-state 13C NMR: Selection of individual 13C- 13C dipolar interactions

    NASA Astrophysics Data System (ADS)

    Spano, Justin; Wi, Sungsool

    2010-06-01

    Herein is described a useful approach in solid-state NMR, for selecting homonuclear 13C- 13C spin pairs in a multiple- 13C homonuclear dipolar coupled spin system. This method builds upon the zero-quantum (ZQ) dipolar recoupling method introduced by Levitt and coworkers (Marin-Montesinos et al., 2006 [30]) by extending the originally introduced one-dimensional (1D) experiment into a two-dimensional (2D) method with selective irradiation scheme, while moving the 13C- 13C mixing scheme from the transverse to the longitudinal mode, together with a dramatic improvement in the proton decoupling efficiency. Selective spin-pair recoupling experiments incorporating Gaussian and cosine-modulated Gaussian pulses for inverting specific spins were performed, demonstrating the ability to detect informative, simplified/individualized, long-range 13C- 13C homonuclear dipolar coupling interactions more accurately by removing less informative, stronger, short-range 13C- 13C interactions from 2D correlation spectra. The capability of this new approach was demonstrated experimentally on uniformly 13C-labeled Glutamine and a tripeptide sample, GAL.

  19. Natural Genetic Variation Influences Protein Abundances in C. elegans Developmental Signalling Pathways

    PubMed Central

    Singh, Kapil Dev; Roschitzki, Bernd; Snoek, L. Basten; Grossmann, Jonas; Zheng, Xue; Elvin, Mark; Kamkina, Polina; Schrimpf, Sabine P.; Poulin, Gino B.; Kammenga, Jan E.; Hengartner, Michael O.

    2016-01-01

    Complex traits, including common disease-related traits, are affected by many different genes that function in multiple pathways and networks. The apoptosis, MAPK, Notch, and Wnt signalling pathways play important roles in development and disease progression. At the moment we have a poor understanding of how allelic variation affects gene expression in these pathways at the level of translation. Here we report the effect of natural genetic variation on transcript and protein abundance involved in developmental signalling pathways in Caenorhabditis elegans. We used selected reaction monitoring to analyse proteins from the abovementioned four pathways in a set of recombinant inbred lines (RILs) generated from the wild-type strains N2 (Bristol) and CB4856 (Hawaii) to enable quantitative trait locus (QTL) mapping. About half of the cases from the 44 genes tested showed a statistically significant change in protein abundance between various strains, most of these were however very weak (below 1.3-fold change). We detected a distant QTL on the left arm of chromosome II that affected protein abundance of the phosphatidylserine receptor protein PSR-1, and two separate QTLs that influenced embryonic and ionizing radiation-induced apoptosis on chromosome IV. Our results demonstrate that natural variation in C. elegans is sufficient to cause significant changes in signalling pathways both at the gene expression (transcript and protein abundance) and phenotypic levels. PMID:26985669

  20. In vivo dynamic turnover of cerebral 13C isotopomers from [U- 13C]glucose

    NASA Astrophysics Data System (ADS)

    Xu, Su; Shen, Jun

    2006-10-01

    An INEPT-based 13C MRS method and a cost-effective and widely available 11.7 Tesla 89-mm bore vertical magnet were used to detect dynamic 13C isotopomer turnover from intravenously infused [U- 13C]glucose in a 211 μL voxel located in the adult rat brain. The INEPT-based 1H → 13C polarization transfer method is mostly adiabatic and therefore minimizes signal loss due to B 1 inhomogeneity of the surface coils used. High quality and reproducible data were acquired as a result of combined use of outer volume suppression, ISIS, and the single-shot three-dimensional localization scheme built in the INEPT pulse sequence. Isotopomer patterns of both glutamate C4 at 34.00 ppm and glutamine C4 at 31.38 ppm are dominated first by a doublet originated from labeling at C4 and C5 but not at C3 (with 1JC4C5 = 51 Hz) and then by a quartet originated from labeling at C3, C4, and C5 (with 1JC3C4 = 35 Hz). A lag in the transition of glutamine C4 pattern from doublet-dominance to quartet dominance as compared to glutamate C4 was observed, which provides an independent verification of the precursor-product relationship between neuronal glutamate and glial glutamine and a significant intercompartmental cerebral glutamate-glutamine cycle between neurons and glial cells.

  1. High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy

    NASA Astrophysics Data System (ADS)

    Rossini, Aaron J.; Schlagnitweit, Judith; Lesage, Anne; Emsley, Lyndon

    2015-10-01

    We demonstrate that high field (9.4 T) dynamic nuclear polarization (DNP) at cryogenic (∼100 K) sample temperatures enables the rapid acquisition of natural abundance 1H-2H cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance 2H CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2 h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the 2H solid-state NMR spectra is comparable to that of 1H spectra obtained with state of the art homonuclear decoupling techniques.

  2. Natural abundance high-resolution solid state 2 H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Aliev, Abil E.; Harris, Kenneth D. M.; Apperley, David C.

    1994-08-01

    We report for the first time an approach for natural abundance solid state 2 H NMR spectroscopy involving magic angle sample spinning (MAS), high-power 1 H decoupling (HPPD) and 1 H- 2 H cross polarization (CP). Taking tetrakis(trimethylsilyl)silane (TTMSS), adamantane, 1-chloroadamantane, hexamethylbenzene (HMB), 2,2-dimethyl-1,3-propanediol (DMPD) and 2-hydroxymethyl-2-methyl-1,3-propanediol (HMPD) as examples, it has been shown that the combination of HPPD and MAS can be applied readily to study rotator phase solids, allowing isotropic peaks arising from chemically inequivalent 2 H nuclei to be resolved. For natural abundance samples of TTMSS and chloroadamantane, it has been shown that 2 H CP/HPPD/MAS NMR experiments, involving polarization transfer from 1 H to 2 H, may provide considerable sensitivity enhancement in comparison with single pulse experiments.

  3. Natural abundance high-resolution solid state 2 H NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Aliev, Abil E.; Harris, Kenneth D. M.; Apperley, David C.

    1994-08-01

    We report for the first time an approach for natural abundance solid state 2H NMR spectroscopy involving magic angle sample spinning (MAS), high-power 1H decoupling (HPPD) and 1H- 2H cross polarization (CP). Taking tetrakis(trimethylsilyl)silane (TTMSS), adamantane, 1-chloroadamantane, hexamethylbenzene (HMB), 2,2-dimethyl-1,3-propanediol (DMPD) and 2-hydroxymethyl-2-methyl-1,3-propanediol (HMPD) as examples, it has been shown that the combination of HPPD and MAS can be applied readily to study rotator phase solids, allowing isotropic peaks arising from chemically inequivalent 2H nuclei to be resolved. For natural abundance samples of TTMSS and chloroadamantane, it has been shown that 2H CP/HPPD/MAS NMR experiments, involving polarization transfer from 1H to 2H, may provide considerable sensitivity enhancement in comparison with single pulse experiments.

  4. Increased natural mortality at low abundance can generate an Allee effect in a marine fish

    PubMed Central

    Kuparinen, Anna; Hutchings, Jeffrey A.

    2014-01-01

    Negative density-dependent regulation of population dynamics promotes population growth at low abundance and is therefore vital for recovery following depletion. Inversely, any process that reduces the compensatory density-dependence of population growth can negatively affect recovery. Here, we show that increased adult mortality at low abundance can reverse compensatory population dynamics into its opposite—a demographic Allee effect. Northwest Atlantic cod (Gadus morhua) stocks collapsed dramatically in the early 1990s and have since shown little sign of recovery. Many experienced dramatic increases in natural mortality, ostensibly attributable in some populations to increased predation by seals. Our findings show that increased natural mortality of a magnitude observed for overfished cod stocks has been more than sufficient to fundamentally alter the dynamics of density-dependent population regulation. The demographic Allee effect generated by these changes can slow down or even impede the recovery of depleted populations even in the absence of fishing. PMID:26064531

  5. Increased natural mortality at low abundance can generate an Allee effect in a marine fish.

    PubMed

    Kuparinen, Anna; Hutchings, Jeffrey A

    2014-10-01

    Negative density-dependent regulation of population dynamics promotes population growth at low abundance and is therefore vital for recovery following depletion. Inversely, any process that reduces the compensatory density-dependence of population growth can negatively affect recovery. Here, we show that increased adult mortality at low abundance can reverse compensatory population dynamics into its opposite-a demographic Allee effect. Northwest Atlantic cod (Gadus morhua) stocks collapsed dramatically in the early 1990s and have since shown little sign of recovery. Many experienced dramatic increases in natural mortality, ostensibly attributable in some populations to increased predation by seals. Our findings show that increased natural mortality of a magnitude observed for overfished cod stocks has been more than sufficient to fundamentally alter the dynamics of density-dependent population regulation. The demographic Allee effect generated by these changes can slow down or even impede the recovery of depleted populations even in the absence of fishing. PMID:26064531

  6. High-resolution NMR of hydrogen in organic solids by DNP enhanced natural abundance deuterium spectroscopy.

    PubMed

    Rossini, Aaron J; Schlagnitweit, Judith; Lesage, Anne; Emsley, Lyndon

    2015-10-01

    We demonstrate that high field (9.4 T) dynamic nuclear polarization (DNP) at cryogenic (∼100 K) sample temperatures enables the rapid acquisition of natural abundance (1)H-(2)H cross-polarization magic angle spinning (CPMAS) solid-state NMR spectra of organic solids. Spectra were obtained by impregnating substrates with a solution of the stable DNP polarizing agent TEKPol in tetrachloroethane. Tetrachloroethane is a non-solvent for the solids, and the unmodified substrates are then polarized through spin diffusion. High quality natural abundance (2)H CPMAS spectra of histidine hydrochloride monohydrate, glycylglycine and theophylline were acquired in less than 2h, providing direct access to hydrogen chemical shifts and quadrupolar couplings. The spectral resolution of the (2)H solid-state NMR spectra is comparable to that of (1)H spectra obtained with state of the art homonuclear decoupling techniques. PMID:26363582

  7. Determination of lithium isotopes at natural abundance levels by atomic absorption spectrometry

    USGS Publications Warehouse

    Meier, A.L.

    1982-01-01

    The relationships of the absorption of 6Li and 7Li hollow cathode lamp emissions are used to determine lithium isotopic composition in the natural abundance range of geologic materials. Absorption was found to have a nonlinear dependence upon total lithium concentration and isotopic composition. A method using nonlinear equations to describe the relationship of the absorption of 6Li and 7Li lamp radiation is proposed as a means of calculating isotopic composition that is independent of total lithium concentration.

  8. Area per Lipid and Cholesterol Interactions in Membranes from Separated Local-Field 13C NMR Spectroscopy

    PubMed Central

    Leftin, Avigdor; Molugu, Trivikram R.; Job, Constantin; Beyer, Klaus; Brown, Michael F.

    2014-01-01

    Investigations of lipid membranes using NMR spectroscopy generally require isotopic labeling, often precluding structural studies of complex lipid systems. Solid-state 13C magic-angle spinning NMR spectroscopy at natural isotopic abundance gives site-specific structural information that can aid in the characterization of complex biomembranes. Using the separated local-field experiment DROSS, we resolved 13C-1H residual dipolar couplings that were interpreted with a statistical mean-torque model. Liquid-disordered and liquid-ordered phases were characterized according to membrane thickness and average cross-sectional area per lipid. Knowledge of such structural parameters is vital for molecular dynamics simulations, and provides information about the balance of forces in membrane lipid bilayers. Experiments were conducted with both phosphatidylcholine (dimyristoylphosphatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC)) and egg-yolk sphingomyelin (EYSM) lipids, and allowed us to extract segmental order parameters from the 13C-1H residual dipolar couplings. Order parameters were used to calculate membrane structural quantities, including the area per lipid and bilayer thickness. Relative to POPC, EYSM is more ordered in the ld phase and experiences less structural perturbation upon adding 50% cholesterol to form the lo phase. The loss of configurational entropy is smaller for EYSM than for POPC, thus favoring its interaction with cholesterol in raftlike lipid systems. Our studies show that solid-state 13C NMR spectroscopy is applicable to investigations of complex lipids and makes it possible to obtain structural parameters for biomembrane systems where isotope labeling may be prohibitive. PMID:25418296

  9. Natural abundance 2H-ERETIC-NMR authentication of the origin of methyl salicylate.

    PubMed

    Le Grand, Flore; George, Gerard; Akoka, Serge

    2005-06-29

    Methyl salicylate is a compound currently used in the creation of many flavors. It can be obtained by synthesis or from two natural sources: essential oil of wintergreen and essential oil of sweet birch bark. Deuterium site-specific natural isotope abundance (A(i)) determination by NMR spectroscopy with the method of reference ERETIC ((2)H-ERETIC-NMR) has been applied to this compound. A(i) measurements have been performed on 19 samples of methyl salicylate from different origins, natural/synthetic and commercial/extracted. This study demonstrates that appropriate treatment performed on the data allows discrimination between synthetic and natural samples. Moreover, the representation of intramolecular ratios R(6/5) as a function of R(3/2) distinguishes between synthetics, wintergreen oils, and sweet birch bark oils. PMID:15969485

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Perfusion and diffusion sensitive 13C stimulated-echo MRSI for metabolic imaging of cancer.

    PubMed

    Larson, Peder E Z; Hurd, Ralph E; Kerr, Adam B; Pauly, John M; Bok, Robert A; Kurhanewicz, John; Vigneron, Daniel B

    2013-06-01

    Metabolic imaging with hyperpolarized [1-(13)C]-pyruvate can rapidly probe tissue metabolic profiles in vivo and has been shown to provide cancer imaging biomarkers for tumor detection, progression, and response to therapy. This technique uses a bolus injection followed by imaging within 1-2 minutes. The observed metabolites include vascular components and their generation is also influenced by cellular transport. These factors complicate image interpretation, especially since [1-(13)C]lactate, a metabolic product that is a biomarker of cancer, is also produced by red blood cells. It would be valuable to understand the distribution of metabolites between the vasculature, interstitial space, and intracellular compartments. The purpose of this study was to better understand this compartmentalization by using a perfusion and diffusion-sensitive stimulated-echo acquisition mode (STEAM) MRSI acquisition method tailored to hyperpolarized substrates. Our results in mouse models showed that among metabolites, the injected substrate (13)C-pyruvate had the largest vascular fraction overall while (13)C-alanine had the smallest vascular fraction. We observed a larger vascular fraction of pyruvate and lactate in the kidneys and liver when compared to back muscle and prostate tumor tissue. Our data suggests that (13)C-lactate in prostate tumor tissue voxels was the most abundant labeled metabolite intracellularly. This was shown in STEAM images that highlighted abnormal cancer cell metabolism and suppressed vascular (13)C metabolite signals. PMID:23260391

  12. Comprehensive discovery of 13C labeled metabolites in the bacterium Methylobacterium extorquens AM1 using gas chromatography-mass spectrometry.

    PubMed

    Yang, Song; Hoggard, Jamin C; Lidstrom, Mary E; Synovec, Robert E

    2013-11-22

    Herein, we report the identification of isotopically labeled metabolite peaks (or the lack of labeling) between sets of GC-MS data from Methylobacterium extorquens AM1. M. extorquens AM1 is one of the best-characterized model organisms for the study of C1 metabolism in methylotrophic bacteria, a diverse group of microbes that can use reduced one-carbon (C1) sources, such as methanol and methane as a sole source for both energy generation and carbon assimilation. Application of a match value (MV) based metric was used to rank the metabolite peaks in the data from those exhibiting the most mass spectral indications of labeling, to those not exhibiting any indications of labeling. The MV-based ranking corresponded well with analyst interpretation of the mass spectra. The MV-based method was initially demonstrated and validated using a mixture of 21 standards with data sets generated for mixtures at natural abundance, a mixture with 6 of the compounds labeled, and a 1:1 mixture of the natural abundance and labeled mixtures. Experimental data from TMS-derivatized extracts from the bacterium M. extorquens AM1 grown with natural abundance or (13)C-labeled methanol as the carbon source were analyzed. Of 131 peaks considered for the analysis of M. extorquens AM1, the 40 peaks ranked highest for indications of (13)C labeling were all found to be labeled, while those peaks ranked lower progressed from peaks for which labeling was uncertain, to a larger number of peaks that were clearly not labeled. The list of peaks determined to be labeled forms a library of compounds that are known to be labeled following the methanol metabolic pathway in M. extorquens AM1 that can be further investigated in future work, e.g. fluxomic studies. PMID:24007683

  13. Effect of Environmental Factors on Cyanobacterial Abundance and Cyanotoxins Production in Natural and Drinking Water, Bangladesh.

    PubMed

    Affan, Abu; Khomavis, Hisham S; Al-Harbi, Salim Marzoog; Haque, Mahfuzul; Khan, Saleha

    2015-02-01

    Cyanobacterial blooms commonly appear during the summer months in ponds, lakes and reservoirs in Bangladesh. In these areas, fish mortality, odorous water and fish and human skin irritation and eye inflammation have been reported. The influence of physicochemical factors on the occurrence of cyanobacteria and its toxin levels were evaluated in natural and drinking water in Bangladesh. A highly sensitive immunosorbent assay was used to detect microcystins (MCs). Cyanobacteria were found in 22 of 23 samples and the dominant species were Microcystis aeruginosa, followed by Microcystisflosaquae, Anabeana crassa and Aphanizomenon flosaquae. Cyanobacterial abundance varied from 39 to 1315 x 10(3) cells mL(-1) in natural water and 31 to 49 x 10(3) cells mL(-1) in tap water. MC concentrations were 25-82300 pg mL(-1) with the highest value measured in the fish research pond, followed by Ishakha Lake. In tap water, MC concentrations ranged from 30-32 pg mL(-1). The correlation between nitrate-nitrogen (NO3-N) concentration and cyanobacterial cell abundance was R2 = 0.62 while that between cyanobacterial abundance and MC concentration was R2 = 0.98. The increased NO3-N from fish feed, organic manure, poultry and dairy farm waste and fertilizer from agricultural land eutrophicated the water bodies and triggered cyanobacterial bloom formation. The increased amount of cyanobacteria produced MCs, subsequently reducing the water quality. PMID:26364354

  14. The cluster and single-particle states in 13C (α,α)13C reactions

    NASA Astrophysics Data System (ADS)

    Mynbayev, N. A.; Nurmukhanbetova, A. K.; Goldberg, V. Z.; Rogachev, G. V.; Golovkov, M. S.; Koloberdin, M.; Ivanov, I.; Nauruzbayev, D. K.; Berdibek, Sh S.; Rakhymzhanov, A. M.; Tribble, R. E.

    2016-06-01

    The excitation functions of elastic scattering of 13C on alpha particle have been measured using the thick-target inverse kinematic method at the heavy ion DC-60 cyclotron. The helium gas was used as a target and also as a degrader to stop the beam. New data (including 180°degree) of the resonances close to the threshold in 17O have been obtained.

  15. Analogy between mission critical detection in distributed systems and 13C isotope separation column

    NASA Astrophysics Data System (ADS)

    Boca, Maria L.; Secara, Mihai

    2015-02-01

    Carbon represents the fourth most abundant chemical element in the world, having two stable and one radioactive isotope. The 13 Carbon isotopes, with a natural abundance of 1.1%, plays an important role in numerous applications, such as the study of human metabolism changes, molecular structure studies, non-invasive respiratory tests, Alzheimer tests, air pollution and global warming effects on plants [2]. Distributed systems are increasingly being applied in critical real-time applications and their complexity forces programmers to use design methods which guarantee correctness and increase the maintainability of the products. Objectoriented methodologies are widely used to cope with complexity in any kind of system, but most of them lack a formal foundation to allow the analysis and verification of designs, which is one of the main requirements for dealing with concurrent and reactive systems. This research is intended to make an analogy between two tips of industrial processes, one 13C Isotope Separation Column and other one distributed systems. We try to highlight detection of "mission critical "situations for this two processes and show with one is more critical and needs deeply supervisyon [1], [3].

  16. CARBON-13 NUCLEAR MAGNETIC RESONANCE. 13C CHEMICAL SHIFTS AND 13C-199HG COUPLING CONSTANTS FOR SOME ORGANOMERCURY COMPOUNDS

    EPA Science Inventory

    The (13)C shieldings and (13)C-(199)Hg coupling constants of fourteen phenyl- and seven alkyl- and alkenyl-mercury compounds have been obtained. Substituent effects on the (13)C shieldings are similar to those in nonmercurated phenyl compounds, with a similar relationship between...

  17. Using PLFA Biomarkers and Natural Abundance Stable and Radiocarbon Isotopes to Characterize the Microbial Ecology and Metabolism of Methane Cycling

    NASA Astrophysics Data System (ADS)

    Mills, C. T.; Mandernack, K. W.; Slater, G. F.; Dias, R. F.

    2008-12-01

    Methane generated in the subsurface is a major source of atmospheric CH4, but its release is mitigated by CH4-oxidizing bacteria (methanotrophs). Therefore, it is important to understand the ecology of methanotroph communities in various environments. Phospholipid fatty acid (PLFA) analyses are a particularly useful method for characterizing these communities for two reasons: (1) Many type I and II methanotrophs produce specific PLFA biomarkers that can be used to estimate their populations, and (2) because CH4 is often very depleted in 13C and sometimes 14C, natural abundance δ13CPLFA and Δ14CPLFA values can be used to trace the flow of CH4- derived carbon through microbial ecosystems. We used these tools to evaluate the role of methanotrophs in carbon flow in three different environments: (1) a soil column overlying a coal bed methane (CBM) seep in southwest CO, and pristine, oligotrophic groundwaters within (2) sedimentary and (3) granitic host rocks in Japan. In the soil column impacted by CBM seepage, concentrations of the biomarker PLFAs for type I (16:1ω8cis) and type II (18:1ω8cis) methanotrophs were as high as 13 and 18 nmoles (g dry soil)-1, respectively. Depth profiles of methanotroph PLFA concentrations varied over different sampling dates indicating dynamic populations. δ13CPLFA values of the CBM soils (-25.1 to - 66.9‰) were substantially more negative than those for the control soil (-14.5 to -32.5‰) indicating that CBM is an important carbon source for the CBM-impacted soil microbial community. Δ14CPLFA values (-351 to -936‰) indicate the importance of 14C-dead CBM as a carbon source to the microbial communities, contributing 32 to 66% of total carbon in PLFA structures isolated from shallow soils and 67 to 97% for those isolated from deeper soils. The biomarker for type II methanotrophs, comprised 3 and 18% of total PLFAs in sedimentary and granitic groundwaters, respectively. The Δ14C values determined for type II methanotroph PLFAs

  18. Symbiotic nitrogen fixation in an arid ecosystem measured by sup 15 N natural abundance

    SciTech Connect

    Johnson, G.V. )

    1990-05-01

    Plants dependent on nitrogen fixation have an {sup 15}N abundance similar to the atmosphere, while non-nitrogen fixing plants usually are enriched in {sup 15}N and are similar to soil nitrogen values. The natural abundance of {sup 15}N in leaf tissues and soils was determined to evaluate symbiotic nitrogen fixation by several legumes and actinorhizal species in the Sevilleta Long-term Ecological Research area in central New Mexico. Comparison of {delta}{sup 15}N values for the legume Prosopis glandulosa (mesquite) to adjacent Atriplex canascens (fourwing saltbush) indicated that P. glandulosa obtained 66% of its nitrogen by fixation. The legume Hoffmanseggia jamesii was found to be utilizing soil nitrogen. The {delta}{sup 15}N values for the actinorhizal plants, Elaeagnus angustifolia and Cercocarpus montanus, while below values for soil nitrogen, did not differ from associated non-fixing plants.

  19. 13C breath tests in infections and beyond.

    PubMed

    Kurpad, Anura V; Ajami, Alfred; Young, Vernon R

    2002-09-01

    Stable isotope labeled compounds are widely used as diagnostic probes in medicine. These diagnostic stable isotope probes are now being expanded in their scope, to provide precise indications of the presence or absence of etiologically significant change in metabolism due to a specific disease. This concept exploits a labeled tracer probe that is a specifically designed substrate of a "gateway" enzyme in a discrete metabolic pathway, whose turnover can be measured by monitoring unidirectional precursor product mass flow. An example of such a probe is the 13C-urea breath test, where labeled urea is given to patients with H. pylori infection. Another example of this kind of probe is used to study the tripeptide glutathione (glu-cys-gly, GSH), which is the most abundant cellular thiol, and protects cells from the toxic effects of reactive oxygen species. Within the gamma glutamyl cycle, 5-oxoproline (L-pyroglutamic acid) is a metabolite generated during GSH catabolism, and is metabolized to glutamic acid by 5-oxoprolinase. This enzyme can also utilize the substrate L-2-oxothiazolidone-4-carboxylate (OTC), to generate intracellular cysteine, which is beneficial to the cell. Thus, labeled (13C) OTC would, under enzymatic attack yield cysteine and 13CO2, and can thus track the state and capacity of glutathione metabolism. Similarly, stable isotope labeled probes can be used to track the activity of the rate of homocysteine clearance, lymphocyte CD26, and liver CYP (cytochrome P450) enzyme activity. In the future, these applications should be able to titrate, in vivo, the characteristics of various specific enzyme systems in the body and their response to stress or infection as well as to treatment regimes. PMID:12362798

  20. Studies of individual carbon sites of azurin from Pseudomonas aeruginosa by natural-abundance carbon-13 nuclear magnetic resonance spectroscopy.

    PubMed

    Ugurbil, K; Norton, R S; Allerhand, A; Bersohn, R

    1977-03-01

    The environments of the aromatic residues (and of the single arginine residue) of azurin from Pseudomonas aeruginosa are investigated by means of natural-abundance 13C Fourier transform NMR spectroscopy. In the case of the diamagnetic Cu(I) azurin, all 17 nonprotonated aromatic carbons (and Czota of Arg-79) yield narrow resonances. Furthermore, a single-carbon amide carbonyl resonance with an unusual chemical shift (peak chi) is observed. The pH dependence of chemical shifts is used to identify the resonances of Cgamma of titrating histidines, and of Cgamma and Czota of the two tyrosines. The resonances of Cgamma and Cdelta2 of the single tryptophan residue (and Czota of Arg-79) are also identified. The pKa values of the two tyrosines are different from each other and higher than typical values of "solvent-exposed" tyrosine residues. Two of the four histidine residues do not titrate (in the pH range 4 to 11). The resonance of Cgamma of one histidine exhibits a pH titration with fast proton exchange behavior and a pKa of 7.5 +/- 0.2. The direction of the titration shift indicates that the imidazole form of this histidine is the Ndelta1-H tautomer. The Cgamma resonance of the other titrating histidine exhibits slow exchange behavior with a pKa of about 7. The imidazole form of this histidine is the Nepsilon2-H tautomer. When going to the paramagnetic Cu(II) protein, only 11 of the 19 carbons mentioned above yield resonances that are narrow enough to be detected. Also, some of the observed resonances exhibit significant paramagnetic broadening. A comparison of spectra of fully reduced azurin, mixtures of reduced and oxidized azurin, and fully oxidized azurin yields the following information. (i) Peak chi arises from an amide group that probably is coordinated to the copper. (ii) The two nontitrating histidine residues are probably copper ligands, with Ndelta1 coordinated to the metal. (iii) The side chains of Arg-79 and the two tyrosine residues are not coordinated to

  1. A combination strategy for extraction and isolation of multi-component natural products by systematic two-phase solvent extraction-(13)C nuclear magnetic resonance pattern recognition and following conical counter-current chromatography separation: Podophyllotoxins and flavonoids from Dysosma versipellis (Hance) as examples.

    PubMed

    Yang, Zhi; Wu, Youqian; Wu, Shihua

    2016-01-29

    Despite of substantial developments of extraction and separation techniques, isolation of natural products from natural resources is still a challenging task. In this work, an efficient strategy for extraction and isolation of multi-component natural products has been successfully developed by combination of systematic two-phase liquid-liquid extraction-(13)C NMR pattern recognition and following conical counter-current chromatography separation. A small-scale crude sample was first distributed into 9 systematic hexane-ethyl acetate-methanol-water (HEMWat) two-phase solvent systems for determination of the optimum extraction solvents and partition coefficients of the prominent components. Then, the optimized solvent systems were used in succession to enrich the hydrophilic and lipophilic components from the large-scale crude sample. At last, the enriched components samples were further purified by a new conical counter-current chromatography (CCC). Due to the use of (13)C NMR pattern recognition, the kinds and structures of major components in the solvent extracts could be predicted. Therefore, the method could collect simultaneously the partition coefficients and the structural information of components in the selected two-phase solvents. As an example, a cytotoxic extract of podophyllotoxins and flavonoids from Dysosma versipellis (Hance) was selected. After the systematic HEMWat system solvent extraction and (13)C NMR pattern recognition analyses, the crude extract of D. versipellis was first degreased by the upper phase of HEMWat system (9:1:9:1, v/v), and then distributed in the two phases of the system of HEMWat (2:8:2:8, v/v) to obtain the hydrophilic lower phase extract and lipophilic upper phase extract, respectively. These extracts were further separated by conical CCC with the HEMWat systems (1:9:1:9 and 4:6:4:6, v/v). As results, total 17 cytotoxic compounds were isolated and identified. In general, whole results suggested that the strategy was very

  2. Natural-abundance stable carbon isotopes of small-subunit ribosomal RNA (SSU rRNA) from Guaymas Basin (Mexico)

    NASA Astrophysics Data System (ADS)

    MacGregor, B. J.; Mendlovitz, H.; Albert, D.; Teske, A. P.

    2012-12-01

    Small-subunit ribosomal RNA (SSU rRNA) is a phylogenetically informative molecule found in all species. Because it is poorly preserved in most environments, it is a useful marker for active microbial populations. We are using the natural-abundance stable carbon isotopic composition of specific microbial groups to help identify the carbon substrates contributing to microbial biomass in a variety of marine environments. At Guaymas Basin, hydrothermal fluids interact with abundant sedimentary organic carbon to produce natural gas and petroleum. Where this reaches the sediment surface, it can support dense patches of seafloor life, including Beggiatoa mats. We report here on the stable carbon isotopic composition of SSU rRNA from a Beggiatoa mat transect, a cold background site, a warm site with high oil concentration, and a second Beggiatoa mat. The central part of the transect mat overlay the steepest temperature gradient, and was visually dominated by orange Beggiatoa. This was fringed by white Beggiatoa mat and bare, but still warm, sediment. Methane concentrations were saturating beneath the orange and white mats and at the oily site, lower beneath bare sediment, and below detection at the background site. Our initial hypotheses were that rRNA isotopic composition would be strongly influenced by methane supply, and that archaeal rRNA might be lighter than bacterial due to contributions from methanogens and anaerobic methane oxidizers. We used biotin-labeled oligonucleotides to capture Bacterial and Archaeal SSU rRNA for isotopic determination. Background-site rRNA was isotopically heaviest, and bacterial RNA from below 2 cm at the oily site was lightest, consistent with control by methane. Within the transect mat, however, the pattern was more complicated; at some sediment depths, rRNA from the mat periphery was isotopically lightest. Part of this may be due to the spatially and temporally variable paths followed by hydrothermal fluid, which can include horizontal

  3. Synthesis Of [2h, 13c]M [2h2m 13c], And [2h3,, 13c] Methyl Aryl Sulfones And Sulfoxides

    DOEpatents

    Martinez, Rodolfo A.; Alvarez, Marc A.; Silks, III, Louis A.; Unkefer, Clifford J.; Schmidt, Jurgen G.

    2004-07-20

    The present invention is directed to labeled compounds, [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfones and [.sup.2 H.sub.1, .sup.13 C], [.sup.2 H.sub.2, .sup.13 C] and [.sup.2 H.sub.3, .sup.13 C]methyl aryl sulfoxides, wherein the .sup.13 C methyl group attached to the sulfur of the sulfone or sulfoxide includes exactly one, two or three deuterium atoms and the aryl group is selected from the group consisting of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently, hydrogen, a C.sub.1 -C.sub.4 lower alkyl, a halogen, an amino group from the group consisting of NH.sub.2, NHR and NRR' where R and R' are each a C.sub.1 -C.sub.4 lower alkyl, a phenyl, or an alkoxy group. The present invention is also directed to processes of preparing methyl aryl sulfones and methyl aryl sulfoxides.

  4. Stable Carbon Isotopes (δ 13C) in Coral Skeletons: Experimental Approach and Applications for Paleoceanography

    NASA Astrophysics Data System (ADS)

    Grottoli, A. G.

    2004-12-01

    Scleractinian corals obtain fixed carbon via photosynthesis by their endosymbiotic algae (zooxanthellae) and via hetertrophy (injestion of zooplankton, δ 13C ≈ -17 to -22‰ ). Carbon dioxide (CO2) used for photosynthesis is obtained from seawater (δ 13C ≈ 0%) or from respired CO2 within the coral host. The δ 13C of the carbon used in the formation of the underlying coral skeleton is fractionated as a result of both of these metabolic processes. Here I have pooled evidence from several field and tank experiments on the effect of photosynthesis and heterotrophy of coral skeletal δ 13C. In the experiments, decreases in light levels due to shading or depth resulted in a significant decrease in skeletal δ 13C in all species studied (Pavona gigantea, Pavona clavus, Porites compressa). Decreases in photosynthesis in bleached corals also resulted in a decrease in skeletal δ 13C compared to non-bleached corals growing under the same conditions and at the same location. Skeletal δ 13C also decreased at higher than normal light levels most likely due to photoinhibition. Thus, decreases in photosynthesis due to reduced light levels, due to bleaching-induced decreases in chlorophyll a concentrations, or due to photodamage-induced decreases in functional cholorphyll a, results in significant δ 13C decreases. Comprehensive interpretation of all of the data showed that changes in photosynthesis itself can drive the changes in δ 13C. In field experiments, the addition of natural concentrations of zooplankton to the diet resulted in decreases in skeletal δ 13C. Such a decrease was more pronounced with depth and in P. gigantea compared to P. clavus. In situ feeding experiments have since confirmed these findings. However under tank conditions with unaturally high feeding rates, enhanced nitrogen supply in the diet can disrupt the coral-algal symbiosis, stimlate zooxanthellae growth and photosynthesis, and cause an incrase in skeletal δ 13C. It is proposed that under

  5. Determination of site-specific carbon isotope ratios at natural abundance by carbon-13 nuclear magnetic resonance spectroscopy.

    PubMed

    Caer, V; Trierweiler, M; Martin, G J; Martin, M L

    1991-10-15

    Site-specific natural isotope fractionation of hydrogen studied by deuterium NMR (SNIF-NMR) spectroscopy is a powerful source of information on hydrogen pathways occurring in biosyntheses in natural conditions. The potential of the carbon counterpart of this method has been investigated and compared. Three typical molecular species, ethanol, acetic acid, and vanillin, have been considered. Taking into account the requirements of quantitative 13C NMR, appropriate experimental procedures have been defined and the repeatability and reproducibility of the isotope ratio determinations have been checked in different conditions. It is shown that the carbon version of the SNIF-NMR method is capable of detecting small differences in the carbon-13 content of the ethyl fragment of ethanols from different botanical or synthetic origins. These results are in agreement with mass spectrometry determinations of the overall carbon isotope ratios. Deviations with respect to a statistical distribution of 13C have been detected in the case of acetic acid and vanillin. However, since the method is very sensitive to several kinds of systematic error, only a relative significance can be attached at present to the internal parameters directly accessible. Isotope dilution experiments have also been carried out in order to check the consistency of the results. In the present state of experimental accuracy, the 13C NMR method is of more limited potential than 2H SNIF-NMR spectroscopy. However it may provide complementary information. Moreover it is particularly efficient for detecting and quantifying adulterations that aim to mimic the overall carbon-13 content of a natural compound by adding a selectivity enriched species to a less expensive substrate from a different origin. PMID:1759714

  6. Changes in protein abundance are observed in bacterial isolates from a natural host

    PubMed Central

    Rees, Megan A.; Stinear, Timothy P.; Goode, Robert J. A.; Coppel, Ross L.; Smith, Alexander I.; Kleifeld, Oded

    2015-01-01

    Bacterial proteomic studies frequently use strains cultured in synthetic liquid media over many generations. It is uncertain whether bacterial proteins expressed under these conditions will be the same as the repertoire found in natural environments, or when bacteria are infecting a host organism. Thus, genomic and proteomic characterization of bacteria derived from the host environment in comparison to reference strains grown in the lab, should aid understanding of pathogenesis. Isolates of Corynebacterium pseudotuberculosis were obtained from the lymph nodes of three naturally infected sheep and compared to a laboratory reference strain using bottom-up proteomics, after whole genome sequencing of each of the field isolates. These comparisons were performed following growth in liquid media that allowed us to reach the required protein amount for proteomic analysis. Over 1350 proteins were identified in the isolated strains, from which unique proteome features were revealed. Several of the identified proteins demonstrated a significant abundance difference in the field isolates compared to the reference strain even though there were no obvious differences in the DNA sequence of the corresponding gene or in nearby non-coding DNA. Higher abundance in the field isolates was observed for proteins related to hypoxia and nutrient deficiency responses as well as to thiopeptide biosynthesis. PMID:26528441

  7. GC-MS determination of ratios of stable-isotope labelled to natural urea using [13C15N2]urea for studying urea kinetics in serum and as a means to validate routine methods for the quantitative assay of urea in dialysate.

    PubMed

    Wolthers, B G; Tepper, T; Withag, A; Nagel, G T; de Haan, T H; van Leeuwen, J J; Stegeman, C A; Huisman, R M

    1994-02-01

    A GC-MS determination of urea in serum or spent dialysate is described, using 13C15N2-labelled urea and assaying the area ratio of labelled to natural urea by mass fragmentographic monitoring of fragments m/e 153 and 156, after its eventual conversion into the trimethylsilylether-derivative of 2-hydroxypyrimidine. The procedure can be successfully applied in the follow-up of the disappearance of labelled urea in serum after intravenous injection in man, enabling kinetic parameters of urea to be established, e.g. for purposes of studying the effectiveness of dialysis procedures. Furthermore the method can be used for validation of routine methods for measuring urea in other fluids, in particular dialysate. Examples are given of both applications of the GC-MS method described. PMID:8033352

  8. Determination of 13C isotopic enrichment of valine and threonine by GC-C-IRMS after formation of the N(O,S)-ethoxycarbonyl ethyl ester derivatives of the amino acids.

    PubMed

    Godin, Jean-Philippe; Faure, Magali; Breuille, Denis; Hopfgartner, Gérard; Fay, Laurent-Bernard

    2007-06-01

    We describe a new method of assessing, in a single run, (13)C isotopic enrichment of both Val and Thr by gas chromatography-combustion-isotope-ratio mass spectrometry (GC-C-IRMS). This method characterised by a rapid one-step derivatisation procedure performed at room temperature to form the N(O,S)-ethoxycarbonyl ethyl ester derivatives, and a polar column for GC. The suitability of this method for Val and Thr in in-vivo samples (mucosal hydrolysate) was demonstrated by studying protein metabolism with two tracers ((13)C-valine or (13)C-threonine). The intra-day and inter-day repeatability were both assessed either with standards or with in-vivo samples at natural abundance and at low (13)C isotopic enrichment. For inter-day repeatability CVs were between 0.8 and 1.5% at natural abundance and lower than 5.5% at 0.112 and 0.190 atom% enrichment for Val and Thr, respectively. Overall isotopic precision was studied for eleven standard amino acid derivatives (those of Val, Ala, Leu, Iso, Gly, Pro, Asp, Thr, Ser, Met, and Phe) and was assessed at 0.32 per thousand. The (13)C isotopic measurement was then extended to the other amino acids (Ala, Val, Leu, Iso, Gly, Pro, Thr, and Phe) at natural abundance for in-vivo samples. The isotopic precision was better than 0.002 atom% per amino acid (for n = 4 rats). This analytical method was finally applied to an animal study to measure Thr utilization in protein synthesis. PMID:17468859

  9. /sup 13/C nuclear magnetic resonance studies of cardiac metabolism

    SciTech Connect

    Seeholzer, S.H.

    1985-01-01

    The last decade has witnessed the increasing use of Nuclear Magnetic Resonance (NMR) techniques for following the metabolic fate of compounds specifically labeled with /sup 13/C. The goals of the present study are: (1) to develop reliable quantitative procedures for measuring the /sup 13/C enrichment of specific carbon sites in compounds enriched by the metabolism of /sup 13/C-labeled substrates in rat heart, and (2) to use these quantitative measurements of fractional /sup 13/C enrichment within the context of a mathematical flux model describing the carbon flow through the TCA cycle and ancillary pathways, as a means for obtaining unknown flux parameters. Rat hearts have been perfused in vitro with various combinations of glucose, acetate, pyruvate, and propionate to achieve steady state flux conditions, followed by perfusion with the same substrates labeled with /sup 13/C in specific carbon sites. The hearts were frozen at different times after addition of /sup 13/C-labeled substrates and neutralized perchloric acid extracts were used to obtain high resolution proton-decoupled /sup 13/C NMR spectra at 90.55 MHz. The fractional /sup 13/C enrichment (F.E.) of individual carbon sites in different metabolites was calculated from the area of the resolved resonances after correction for saturation and nuclear Overhauser effects. These F.E. measurements by /sup 13/C NMR were validated by the analysis of /sup 13/C-/sup 1/H scalar coupling patterns observed in /sup 1/H NMR spectra of the extracted metabolites. The results obtained from perfusion of hearts glucose plus either (2-/sup 13/C) acetate or (3-/sup 13/C) pyruvate are similar to those obtained by previous investigators using /sup 14/C-labeled substrates.

  10. Continuous Flow - Cavity RingDown Spectroscopy Using a Novel Universal Interface for High-Precision Bulk 13C Analysis

    NASA Astrophysics Data System (ADS)

    Saad, Nabil; Richman, Bruce

    2010-05-01

    We have developed the world's first optical spectroscopy-based system for bulk stable isotope analysis of 13C. The system is based on a novel universal interface, named LIAISON, capable of coupling to almost any CO2-generating sample preparation front-end ranging from an elemental analyzer to any dissolved carbon analysis module, which are of significant use in geochemical, ecological and food authentication studies. In one specific application, we have coupled LIAISON to an elemental analyzer (EA) and to a cavity ring-down spectrometer (CRDS) for 13C isotopic analysis of adulterated honey samples. Another application was developed to analyze dissolved inorganic carbon in water samples. LIAISON is suited for handling a high-throughput sample analysis process by running three different gas handling operations in parallel: Admitting combustion gas from the EA into a first gas bellows, analyzing the previous sample collected into a second gas bellows with CRDS, and flushing and purging a third gas bellows in preparation for the upcoming sample collection operation. The sample-to-sample analysis time is 10 minutes and the operation is completely automated for the whole front-end auto-sampler tray capacity, requiring no operator intervention. The CRDS data are collected, tabulated and saved into an output text file. The memory effect between the USGS L-Glutamic acid standard at natural abundance and the moderately enriched USGS L-Glutamic acid standard is excluded by the selection of the adequate number and duration of flush and purge cycles of the gas sample bags. The system's proven accuracy was cross-checked with EA-IRMS and its achieved precision was typically less than 0.2 permil, including the 13C-enriched tested samples. The LIAISON-CRDS system presented here provides a fully automated solution for 13C bulk stable isotope analysis with unprecedented ease-of-use and possible field portability and application with the availability of a compact front-end. In

  11. Fluxomers: a new approach for 13C metabolic flux analysis

    PubMed Central

    2011-01-01

    Background The ability to perform quantitative studies using isotope tracers and metabolic flux analysis (MFA) is critical for detecting pathway bottlenecks and elucidating network regulation in biological systems, especially those that have been engineered to alter their native metabolic capacities. Mathematically, MFA models are traditionally formulated using separate state variables for reaction fluxes and isotopomer abundances. Analysis of isotope labeling experiments using this set of variables results in a non-convex optimization problem that suffers from both implementation complexity and convergence problems. Results This article addresses the mathematical and computational formulation of 13C MFA models using a new set of variables referred to as fluxomers. These composite variables combine both fluxes and isotopomer abundances, which results in a simply-posed formulation and an improved error model that is insensitive to isotopomer measurement normalization. A powerful fluxomer iterative algorithm (FIA) is developed and applied to solve the MFA optimization problem. For moderate-sized networks, the algorithm is shown to outperform the commonly used 13CFLUX cumomer-based algorithm and the more recently introduced OpenFLUX software that relies upon an elementary metabolite unit (EMU) network decomposition, both in terms of convergence time and output variability. Conclusions Substantial improvements in convergence time and statistical quality of results can be achieved by applying fluxomer variables and the FIA algorithm to compute best-fit solutions to MFA models. We expect that the fluxomer formulation will provide a more suitable basis for future algorithms that analyze very large scale networks and design optimal isotope labeling experiments. PMID:21846358

  12. Differences in the fractional abundances of carbohydrates of natural and recombinant human tissue factor

    PubMed Central

    Krudysz-Amblo, Jolanta; Jennings, Mark E; Matthews, Dwight E; Mann, Kenneth G; Butenas, Saulius

    2011-01-01

    Tissue factor (TF) is a single polypeptide integral membrane glycoprotein composed of 263 residues and is essential to life in its role as the initiator of blood coagulation. Objective Previously we have shown that the activity of the natural placental TF (pTF) and the recombinant TF (rTF) from Sf9 insect cells is different (Krudysz-Amblo, J. et al(2010) J. Biol. Chem. 285, 3371–3382). In this study, using mass spectrometry, we show by quantitative analysis that the extent of glycosylation varies on each protein. Results Fractional abundance, of each glycan composition at each of the three glycosylation sites, reveals the most pronounced difference to be at asparagine (Asn) 11. This residue is located in the region of extensive TFfactor VIIa (FVIIa) interaction. Carbohydrate fractional abundance at Asn11 revealed that glycosylation in the natural placental TF is much more prevalent (~76%) than in the recombinant protein (~20%). The extent of glycosylation on Asn124 and Asn137 is similar in the two proteins, despite the pronounced differences in the carbohydrate composition. Additionally, 77% of rTF exists as TF des-1, 2 (missing the first two amino acids from the N-terminus). In contrast, only 31% of pTF is found in the des-1, 2 form. Conclusion These observations may attribute to the difference in the ability of TF-FVIIa complex to activate factor X (FX). Structural and functional comparison of the recombinant and natural protein advances our understanding and knowledge on the biological activity of TF. PMID:21172408

  13. Non-stationary (13)C-metabolic flux ratio analysis.

    PubMed

    Hörl, Manuel; Schnidder, Julian; Sauer, Uwe; Zamboni, Nicola

    2013-12-01

    (13)C-metabolic flux analysis ((13)C-MFA) has become a key method for metabolic engineering and systems biology. In the most common methodology, fluxes are calculated by global isotopomer balancing and iterative fitting to stationary (13)C-labeling data. This approach requires a closed carbon balance, long-lasting metabolic steady state, and the detection of (13)C-patterns in a large number of metabolites. These restrictions mostly reduced the application of (13)C-MFA to the central carbon metabolism of well-studied model organisms grown in minimal media with a single carbon source. Here we introduce non-stationary (13)C-metabolic flux ratio analysis as a novel method for (13)C-MFA to allow estimating local, relative fluxes from ultra-short (13)C-labeling experiments and without the need for global isotopomer balancing. The approach relies on the acquisition of non-stationary (13)C-labeling data exclusively for metabolites in the proximity of a node of converging fluxes and a local parameter estimation with a system of ordinary differential equations. We developed a generalized workflow that takes into account reaction types and the availability of mass spectrometric data on molecular ions or fragments for data processing, modeling, parameter and error estimation. We demonstrated the approach by analyzing three key nodes of converging fluxes in central metabolism of Bacillus subtilis. We obtained flux estimates that are in agreement with published results obtained from steady state experiments, but reduced the duration of the necessary (13)C-labeling experiment to less than a minute. These results show that our strategy enables to formally estimate relative pathway fluxes on extremely short time scale, neglecting cellular carbon balancing. Hence this approach paves the road to targeted (13)C-MFA in dynamic systems with multiple carbon sources and towards rich media. PMID:23860906

  14. Abundance and phenology patterns of two pond-breeding salamanders determine species interactions in natural populations.

    PubMed

    Anderson, Thomas L; Hocking, Daniel J; Conner, Christopher A; Earl, Julia E; Harper, Elizabeth B; Osbourn, Michael S; Peterman, William E; Rittenhouse, Tracy A G; Semlitsch, Raymond D

    2015-03-01

    Phenology often determines the outcome of interspecific interactions, where early-arriving species often dominate interactions over those arriving later. The effects of phenology on species interactions are especially pronounced in aquatic systems, but the evidence is largely derived from experimental studies. We examined whether differences in breeding phenology between two pond-breeding salamanders (Ambystoma annulatum and A. maculatum) affected metamorph recruitment and demographic traits within natural populations, with the expectation that the fall-breeding A. annulatum would negatively affect the spring-breeding A. maculatum. We monitored populations of each species at five ponds over 4 years using drift fences. Metamorph abundance and survival of A. annulatum were affected by intra- and interspecific processes, whereas metamorph size and date of emigration were primarily influenced by intraspecific effects. Metamorph abundance, snout-vent length, date of emigration and survival for A. maculatum were all predicted by combinations of intra- and interspecific effects, but often showed negative relationships with A. annulatum metamorph traits and abundance. Size and date of metamorphosis were strongly correlated within each species, but in opposite patterns (negative for A. annulatum and positive for A. maculatum), suggesting that the two species use alternative strategies to enhance terrestrial survival and that these factors may influence their interactions. Our results match predictions from experimental studies that suggest recruitment is influenced by intra- and interspecific processes which are determined by phenological differences between species. Incorporating spatiotemporal variability when modeling population dynamics is necessary to understand the importance of phenology in species interactions, especially as shifts in phenology occur under climate change. PMID:25413866

  15. On the nature of lithium-rich giant stars. Constraints from beryllium abundances

    NASA Astrophysics Data System (ADS)

    Melo, C. H. F.; de Laverny, P.; Santos, N. C.; Israelian, G.; Randich, S.; Do Nascimento, J. D., Jr.; de Medeiros, J. R.

    2005-08-01

    We have derived beryllium abundances for 7 Li-rich giant (A(Li) > 1.5) stars and 10 other Li-normal giants with the aim of investigating the origin of the lithium in the Li-rich giants. In particular, we test the predictions of the engulfment scenario proposed by Siess & Livio (1999, MNRAS, 308, 1133), where the engulfment of a brown dwarf or one or more giant planets would lead to simultaneous enrichment of 7Li and 9Be. We show that regardless of their nature, none of the stars studied in this paper were found to have detectable beryllium. Using simple dilution arguments we show that engulfment of an external object as the sole source of Li enrichment is ruled out by the Li and Be abundance data. The present results favor the idea that Li has been produced in the interior of the stars by a Cameron-Fowler process and brought up to the surface by an extra mixing mechanism.

  16. Distribution and Abundance of Insertion Sequences among Natural Isolates of Escherichia coli

    PubMed Central

    Sawyer, Stanley A.; Dykhuizen, Daniel E.; DuBose, Robert F.; Green, Louis; Mutangadura-Mhlanga, T.; Wolczyk, David F.; Hartl, Daniel L.

    1987-01-01

    A reference collection of 71 natural isolates of Escherichia coli (the ECOR collection) has been studied with respect to the distribution and abundance of transposable insertion sequences using DNA hybridization. The data include 1173 occurrences of six unrelated insertion sequences (IS 1, IS2, IS3, IS4, IS5 and IS 30). The number of insertion elements per strain, and the sizes of DNA restriction fragments containing them, is highly variable and can be used to discriminate even among closely related strains. The occurrence and abundance of pairs of unrelated insertion sequences are apparently statistically independent, but significant correlations result from stratifications in the reference collection. However, there is a highly significant positive association among the insertion sequences considered in the aggregate. Nine branching process models, which differ in assumptions regarding the regulation of transposition and the effect of copy number on fitness, have been evaluated with regard to their fit of the observed distributions. No single model fits all copy number distributions. The best models incorporate no regulation of transposition and a moderate to strong decrease in fitness with increasing copy number for IS1 and IS5, strong regulation of transposition and a negligible to weak decrease in fitness with increasing copy number for IS3, and less than strong regulation of transposition for IS2, IS 4 and IS30. PMID:3030884

  17. Studies of individual carbon sites of proteins in solution by natural abundance carbon 13 nuclear magnetic resonance spectroscopy. Strategies for assignments.

    PubMed

    Oldfield, E; Norton, R S; Allerhand, A

    1975-08-25

    Natural abundance 13C Fourier transform NMR spectra (at 15.18 MHz, in 20-mm sample tubes) of aqueous native proteins yield numerous narrow single carbon resonances of nonprotonated aromatic carbons. Techniques for the assignment of these resonances are presented. Each technique is applied to one or more of the following proteins: ferricytochrome c from horse heart and Candida krusei, ferrocytochrome c and cyanoferricytochrome c from horse heart, lysozyme from hen egg white, cyanoferrimyoglobins from horse and sperm whale skeletal muscle, and carbon monoxide myoglobin from horse. In all of the protein spectra we have examined, methine aromatic carbons give rise to broad bands. Studies of the narrow resonances of nonprotonated aromatic carbons of proteins are facilitated by removal of these broad bands by means of the convolution-difference method, preferably from spectra recorded under conditions of noise-modulated off-resonance proton decoupling. We present a summary of the chemical shift ranges for the various types of nonprotonated aromatic carbons of amino acid residues and hemes of diamagnetic proteins, based on our results for hen egg white lysozyme, horse heart ferrocytochrome c, horse carbon monoxide myoglobin, and carbon monoxide hemoglobins from various species... PMID:169240

  18. Functional groups identified by solid state 13C NMR spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Animal manure is generally high in organic matter intensity so it is well suitable for 13C nuclear magnetic resonance (NMR) analysis. Solid-state 13C NMR techniques used in characterizing organic matter and its components include, but are not limited to, cross-polarization /magic angle spinning (CP...

  19. Natural abundant (17) O NMR in a 1.5-T Halbach magnet.

    PubMed

    Sørensen, Morten K; Bakharev, Oleg N; Jensen, Ole; Nielsen, Niels Chr

    2016-06-01

    We present mobile, low-field (17) O NMR as a means for monitoring oxygen in liquids. Whereas oxygen is one of the most important elements, oxygen NMR is limited by a poor sensitivity related to low natural abundance and gyro-magnetic ratio of the NMR active (17) O isotope. Here, we demonstrate (17) O NMR detection at a Larmor frequency of 8.74 MHz in a 1.5-T Halbach neodymium magnet with a home-built digital NMR instrument suitable for large-scale production and in-line monitoring applications. The proposed (17) O NMR sensor may be applied for direct, noninvasive measurements of water content in, for example, oil, manure, or food in automated quality or process control. Copyright © 2015 John Wiley & Sons, Ltd. PMID:25641664

  20. Natural abundance 14N and 15N solid-state NMR of pharmaceuticals and their polymorphs

    DOE PAGESBeta

    Veinberg, Stanislav L.; Johnston, Karen E.; Jaroszewicz, Michael J.; Kispal, Brianna M.; Mireault, Christopher R.; Kobayashi, Takeshi; Pruski, Marek; Schurko, Robert W.

    2016-06-08

    14N ultra-wideline (UW), 1H{15N} indirectly-detected HETCOR (idHETCOR) and 15N dynamic nuclear polarization (DNP) solid-state NMR (SSNMR) experiments, in combination with plane-wave density functional theory (DFT) calculations of 14N EFG tensors, were utilized to characterize a series of nitrogen-containing active pharmaceutical ingredients (APIs), including HCl salts of scopolamine, alprenolol, isoprenaline, acebutolol, dibucaine, nicardipine, and ranitidine. Here, a case study applying these methods for the differentiation of polymorphs of bupivacaine HCl is also presented. All experiments were conducted upon samples with naturally-abundant nitrogen isotopes. For most of the APIs, it was possible to acquire frequency-stepped UW 14N SSNMR spectra of stationarymore » samples, which display powder patterns corresponding to pseudo-tetrahedral (i.e., RR'R"NH+ and RR'NH2+) or other (i.e., RNH2 and RNO2) nitrogen environments.« less

  1. HCNMBC - A pulse sequence for H-(C)-N Multiple Bond Correlations at natural isotopic abundance

    NASA Astrophysics Data System (ADS)

    Cheatham, Steve; Gierth, Peter; Bermel, Wolfgang; Kupče, Ēriks

    2014-10-01

    We propose a pulse sequence, HCNMBC for multiple-bond H-(C)-N correlation experiments via one-bond 1J(C,H) and one- or multiple bond nJ(N,C) coupling constants (typically n = 1-3) at the natural isotopic abundance. A new adiabatic refocussing sequence is introduced to provide accurate and robust refocussing of both chemical shift and J-evolution over wide ranges of C-13 and N-15 frequencies. It is demonstrated that the proposed pulse sequence provides high quality spectra even for sub-milligram samples. We show that when a 1.7 mm cryoprobe is available as little as 10 μg of glycine in D2O is sufficient to obtain the HCNMBC spectrum in ca. 12 h. The preliminary results indicate that the pulse sequence has a great potential in the structure determination of nitrogen heterocycles especially in cases where synthesis produces regioisomers.

  2. Dissecting the Mechanisms of a Class of Chemical Glycosylation Using Primary 13C Kinetic Isotope Effects

    PubMed Central

    Huang, Min; Garrett, Graham E.; Birlirakis, Nicolas; Bohé, Luis

    2012-01-01

    Although arguably the most important reaction in glycoscience, chemical glycosylations are among the least well understood of organic chemical reactions resulting in an unnecessarily high degree of empiricism and a brake on rational development in this critical area. To address this problem primary 13C kinetic isotope effects now have been determined for the formation of β- and α-manno- and glucopyranosides by a natural abundance NMR method. In contrast to the common current assumption, for three of the four cases studied the experimental values concur with those computed for associative displacement of the intermediate covalent glycosyl trifluoromethanesulfonates. For the formation of the α-mannopyranosides the experimentally determined KIE differs significantly from that computed for an associative displacement, which is strongly suggestive of a dissociative mechanism that approaches the intermediacy of a glycosyl oxocarbenium ion. The application of comparable experiments to other glycosylation systems should shed further light on their glycosylation mechanisms and thus assist in the design of better reactions conditions with improved stereoselectivity. PMID:22824899

  3. Dissecting the mechanisms of a class of chemical glycosylation using primary 13C kinetic isotope effects

    NASA Astrophysics Data System (ADS)

    Huang, Min; Garrett, Graham E.; Birlirakis, Nicolas; Bohé, Luis; Pratt, Derek A.; Crich, David

    2012-08-01

    Although arguably the most important reaction in glycoscience, chemical glycosylations are among the least well understood of organic chemical reactions, resulting in an unnecessarily high degree of empiricism and a brake on rational development in this critical area. To address this problem, primary 13C kinetic isotope effects have now been determined for the formation of β- and α-manno- and glucopyranosides using a natural abundance NMR method. In contrast to the common current assumption, for three of the four cases studied the experimental and computed values are indicative of associative displacement of the intermediate covalent glycosyl trifluoromethanesulfonates. For the formation of the α-mannopyranosides, the experimentally determined KIE differs significantly from that computed for an associative displacement, which is strongly suggestive of a dissociative mechanism that approaches the intermediacy of a glycosyl oxocarbenium ion. The application of analogous experiments to other glycosylation systems should shed further light on their mechanisms and thus assist in the design of better reactions conditions with improved stereoselectivity.

  4. FTIR and NDIR spectroscopies as valuable alternatives to IRMS spectrometry for the δ(13)C analysis of food.

    PubMed

    Pironti, Concetta; Proto, Antonio; Camin, Federica; Cucciniello, Raffaele; Zarrella, Ilaria; Motta, Oriana

    2016-11-01

    The (13)C/(12)C carbon isotope ratio is a chemical parameter with many important applications in several scientific area and the technique of choice currently used for the δ(13)C determination is the isotope ratio mass spectrometry (IRMS). This latter is highly accurate (0.1‰) and sensitive (up to 0.01‰), but at the same time expensive and complex. The objective of this work was to assess the reliability of FTIR and NDIRS techniques for the measurement of carbon stable isotope ratio of food sample, in comparison to IRMS. IRMS, NDIRS and FTIR were used to analyze samples of food, such as oil, durum, cocoa, pasta and sugar, in order to determine the natural abundance isotopic ratio of carbon in a parallel way. The results were comparable, showing a close relationship among the three techniques. The main advantage in using FTIR and NDIRS is related to their cheapness and easy-to-operate in comparison to IRMS. PMID:27591614

  5. State-of-the-Art Direct 13C and Indirect 1H-[13C] NMR Spectroscopy In Vivo

    PubMed Central

    de Graaf, Robin A.; Rothman, Douglas L.; Behar, Kevin L.

    2013-01-01

    Carbon-13 NMR spectroscopy in combination with 13C-labeled substrate infusion is a powerful technique to measure a large number of metabolic fluxes non-invasively in vivo. It has been used to quantify glycogen synthesis rates, establish quantitative relationships between energy metabolism and neurotransmission and evaluate the importance of different substrates. All measurements can, in principle, be performed through direct 13C NMR detection or via indirect 1H-[13C] NMR detection of the protons attached to 13C nuclei. The choice for detection scheme and pulse sequence depends on the magnetic field strength, whereas substrate selection depends on the metabolic pathways that are studied. 13C NMR spectroscopy remains a challenging technique that requires several non-standard hardware modifications, infusion of 13C-labeled substrates and sophisticated processing and metabolic modeling. Here the various aspects of direct 13C and indirect 1H-[13C] NMR are reviewed with the aim of providing a practical guide. PMID:21919099

  6. Analysis of dissolved organic carbon concentration and 13C isotopic signature by TOC-IRMS - assessment of analytical performance

    NASA Astrophysics Data System (ADS)

    Kirkels, Frédérique; Cerli, Chiara; Federherr, Eugen; Kalbitz, Karsten

    2013-04-01

    Stable carbon isotopes provide a powerful tool to assess carbon pools and their dynamics. Dissolved organic carbon (DOC) has been recognized to play an important role in ecosystem functioning and carbon cycling and has therefore gained increased research interest. However, direct measurement of 13C isotopic signature of carbon in the dissolved phase is technically challenging particularly using high temperature combustion. Until recently, mainly custom-made systems existed which were modified for coupling of TOC instruments with IRMS for simultaneous assessment of C content and isotopic signature. The variety of coupled systems showed differences in their analytical performances. For analysis of DOC high temperature combustion is recognized as best performing method, owing to its high efficiency of conversion to CO2 also for highly refractory components (e.g. humic, fulvic acids) present in DOC and soil extracts. Therefore, we tested high temperature combustion TOC coupled to IRMS (developed by Elementar Group) for bulk measurements of DOC concentration and 13C signature. The instruments are coupled via an Interface to exchange the carrier gas from O2 to He and to concentrate the derived CO2 for the isotope measurement. Analytical performance of the system was assessed for a variety of organic compounds characterized by different stability and complexity, including humic acid and DOM. We tested injection volumes between 0.2-3 ml, thereby enabling measurement of broad concentration ranges. With an injection volume of 0.5 ml (n=3, preceded by 1 discarded injection), DOC and 13C signatures for concentrations between 5-150 mg C/L were analyzed with high precision (standard deviation (SD) predominantly <0.1‰), good accuracy and linearity (overall SD <0.9‰). For the same settings, slightly higher variation in precision was observed among the lower concentration range and depending upon specific system conditions. Differences in 13C signatures of about 50‰ among

  7. Sensitivity-enhanced IPAP experiments for measuring one-bond 13C '- 13C α and 13C α- 1H α residual dipolar couplings in proteins

    NASA Astrophysics Data System (ADS)

    Ding, Keyang; Gronenborn, Angela M.

    2004-04-01

    Sensitivity-enhanced 2D IPAP experiments using the accordion principle for measuring one-bond 13C '- 13C α and 1H α- 13C α dipolar couplings in proteins are presented. The resolution of the resulting spectra is identical to that of the decoupled HSQC spectra and the sensitivity of the corresponding 1D acquisitions are only slightly lower than those obtained with 3D HNCO and 3D HN(COCA)HA pulse sequences due to an additional delay 2 Δ. For cases of limited resolution in the 2D 15N- 1H N HSQC spectrum the current pulse sequences can easily be modified into 3D versions by introducing a poorly digitized third dimension, if so desired. The experiments described here are a valuable addition to the suites available for determination of residual dipolar couplings in biological systems.

  8. On the nature of sn stars. I. A detailed abundance study

    NASA Astrophysics Data System (ADS)

    Saffe, C.; Levato, H.

    2014-02-01

    The sn stars were first discoved by Abt & Levato when studying the spectral types in different open clusters. These stars present sharp Balmer lines, sharp metallic lines (C II, Si II, Ca II, Ti II, Fe II), and broad coreless He I lines. Some of the sn stars seem to be related to CP stars. Initially Abt & Levato proposed a shell-like nature to explain the sn stars, although this scenario was subsequently questioned. There is no general agreement about their origin. We aim to derive abundances for a sample of 9 stars, including sn and non-sn stars, to determine the possible relation between sn and CP stars and compare their chemical abundances. That most sn stars belong to open clusters allows us to search for a possible relation with fundamental parameters, including the age and rotation. We also study the possible contribution of different effects to the broad He I lines observed in these stars, such as Stark broadening and the possible He-stratification. Effective temperature and gravity were estimated by Strömgren photometry and then refined by requiring ionization and excitation equilibrium of Fe lines. We derived the abundances by fitting the observed spectra with synthetic spectra using an iterative procedure with the SYNTHE and ATLAS9 codes. We derived metallic abundances of 23 different chemical elements for 9 stars and obtained low projected rotational velocities for the sn stars in our sample (vsini up to 69 km s-1). We also compared 5 stars that belong to the same cluster (NGC 6475) and show that the sn characteristics appear in the 3 stars with the lower rotational velocity. However, the apparent preference of sn stars for objects with the lower vsini values should be taken with caution due to the small number of objects studied here. We analysed the photospheric chemical composition of sn stars and show that approximately ~40% of them display chemical peculiarities (such as He-weak and HgMn stars) within a range of temperature of 10 300 K-14 500 K

  9. Quality assurance of PASADENA hyperpolarization for 13C biomolecules

    PubMed Central

    Hövener, Jan-Bernd; Chekmenev, Eduard Y.; Harris, Kent C.; Perman, William H.; Tran, Thao T.; Bhattacharya, Pratip

    2009-01-01

    Object Define MR quality assurance procedures for maximal PASADENA hyperpolarization of a biological 13C molecular imaging reagent. Materials and methods An automated PASADENA polarizer and a parahydrogen generator were installed. 13C enriched hydroxyethyl acrylate, 1-13C, 2,3,3-d3 (HEA), was converted to hyperpolarized hydroxyethyl propionate, 1-13C, 2,3,3-d3 (HEP) and fumaric acid, 1-13C, 2,3-d2 (FUM) to hyperpolarized succinic acid, 1-13C, 2,3-d2 (SUC), by reaction with parahydrogen and norbornadiene rhodium catalyst. Incremental optimization of successive steps in PASADENA was implemented. MR spectra and in vivo images of hyperpolarized 13C imaging agents were acquired at 1.5 and 4.7 T. Results Application of quality assurance (QA) criteria resulted in incremental optimization of the individual steps in PASADENA implementation. Optimal hyperpolarization of HEP of P = 20% was achieved by calibration of the NMR unit of the polarizer (B0 field strength ± 0.002 mT). Mean hyperpolarization of SUC, P = [15.3 ± 1.9]% (N = 16) in D2O, and P = [12.8 ± 3.1]% (N = 12) in H2O, was achieved every 5–8 min (range 13–20%). An in vivo 13C succinate image of a rat was produced. Conclusion PASADENA spin hyperpolarization of SUC to 15.3% in average was demonstrated (37,400 fold signal enhancement at 4.7 T). The biological fate of 13C succinate, a normally occurring cellular intermediate, might be monitored with enhanced sensitivity. PMID:19067009

  10. Archaeal community diversity and abundance changes along a natural salinity gradient in estuarine sediments

    PubMed Central

    Webster, Gordon; O'Sullivan, Louise A.; Meng, Yiyu; Williams, Angharad S.; Sass, Andrea M.; Watkins, Andrew J.; Parkes, R. John; Weightman, Andrew J.

    2014-01-01

    Archaea are widespread in marine sediments, but their occurrence and relationship with natural salinity gradients in estuarine sediments is not well understood. This study investigated the abundance and diversity of Archaea in sediments at three sites [Brightlingsea (BR), Alresford (AR) and Hythe (HY)] along the Colne Estuary, using quantitative real-time PCR (qPCR) of 16S rRNA genes, DNA hybridization, Archaea 16S rRNA and mcrA gene phylogenetic analyses. Total archaeal 16S rRNA abundance in sediments were higher in the low-salinity brackish sediments from HY (2–8 × 107 16S rRNA gene copies cm−3) than the high-salinity marine sites from BR and AR (2 × 104–2 × 107 and 4 × 106–2 × 107 16S rRNA gene copies cm−3, respectively), although as a proportion of the total prokaryotes Archaea were higher at BR than at AR or HY. Phylogenetic analysis showed that members of the ‘Bathyarchaeota’ (MCG), Thaumarchaeota and methanogenic Euryarchaeota were the dominant groups of Archaea. The composition of Thaumarchaeota varied with salinity, as only ‘marine’ group I.1a was present in marine sediments (BR). Methanogen 16S rRNA genes from low-salinity sediments at HY were dominated by acetotrophic Methanosaeta and putatively hydrogentrophic Methanomicrobiales, whereas the marine site (BR) was dominated by mcrA genes belonging to methylotrophic Methanococcoides, versatile Methanosarcina and methanotrophic ANME-2a. Overall, the results indicate that salinity and associated factors play a role in controlling diversity and distribution of Archaea in estuarine sediments. PMID:25764553

  11. Geochemical Approach to Archaeal Ecology: δ13C of GDGTs

    NASA Astrophysics Data System (ADS)

    Lichtin, S.; Warren, C.; Pearson, A.; Pagani, M.

    2015-12-01

    Over the last decade and a half, glycerol dialkyl glycerol tetraethers (GDGTs) have increasingly been used to reconstruct environmental temperatures; proxies like TEX86 that correlate the relative abundance of these archaeal cell membrane lipids to sea surface temperature are omnipresent in paleoclimatology literature. While it has become common to make claims about past temperatures using GDGTs, our present understanding of the organisms that synthesize the compounds is still quite limited. The generally accepted theory states that microorganisms like the Thaumarchaeota modify the structure of membrane lipids to increase intermolecular interactions, strengthening the membrane at higher temperatures. Yet to date, culture experiments have been largely restricted to a single species, Nitrosopumilus maritimes, and recent studies on oceanic archaeal rRNA have revealed that these biomarkers are produced in diverse, heterogeneous, and site-specific communities. This brings up questions as to whether different subclasses of GDGTs, and all subsequent proxies, represent adaptation within a single organismal group or a shift in community composition. To investigate whether GDGTs with different chain structures, from the simple isoprenoidal GDGT-0 to Crenarchaeol with its many cyclopentane groups, are sourced from archaea with similar or disparate metabolic pathways—and if that information is inherited in GDGTs trapped in marine sediments—this study examines the stable carbon isotope values (δ13C) of GDGTs extracted from the uppermost meters of sediment in the Orca Basin, Gulf of Mexico, using spooling-wire microcombustion isotope-ratio mass spectrometer (SWiM-IRMS), tackling a fundamental assumption of the TEX86 proxy that influences the way we perceive the veracity of existing temperature records.

  12. Determination of Natural 14C Abundances in Dissolved Organic Carbon in Organic-Rich Marine Sediment Porewaters by Thermal Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Johnson, L.; Komada, T.

    2010-12-01

    The abundances of natural 14C in dissolved organic carbon (DOC) in the marine environment hold clues regarding the processes that influence the biogeochemical cycling of this large carbon reservoir. At present, UV irradiation is the widely accepted method for oxidizing seawater DOC for determination of their 14C abundances. This technique yields precise and accurate values with low blanks, but it requires a dedicated vacuum line, and hence can be difficult to implement. As an alternative technique that can be conducted on a standard preparatory vacuum line, we modified and tested a thermal sulfate reduction method that was previously developed to determine δ13C values of marine DOC (Fry B. et al., 1996. Analysis of marine DOC using a dry combustion method. Mar. Chem., 54: 191-201.) to determine the 14C abundances of DOC in marine sediment porewaters. In this method, the sample is dried in a 100 ml round-bottom Pyrex flask in the presence of excess oxidant (K2SO4) and acid (H3PO4), and combusted at 550 deg.C. The combustion products are cryogenically processed to collect and quantify CO2 using standard procedures. Materials we have oxidized to date range from 6-24 ml in volume, and 95-1500 μgC in size. The oxidation efficiency of this method was tested by processing known amounts of reagent-grade dextrose and sucrose (as examples of labile organic matter), tannic acid and humic acid (as examples of complex natural organic matter), and porewater DOC extracted from organic-rich nearshore sediments. The carbon yields for all of these materials averaged 99±4% (n=18). The 14C abundances of standard materials IAEA C-6 and IAEA C-5 processed by this method using >1mgC aliquots were within error of certified values. The size and the isotopic value of the blank were determined by a standard dilution technique using IAEA C-6 and IAEA C-5 that ranged in size from 150 to 1500 μgC (n=4 and 2, respectively). This yielded a blank size of 6.7±0.7 μgC, and a blank isotopic

  13. Relative contribution of shoot and ear photosynthesis to grain filling in wheat under good agronomical conditions assessed by differential organ δ13C

    PubMed Central

    Sanchez-Bragado, Rut; Molero, Gemma; Reynolds, Matthew P.; Araus, Jose Luis

    2014-01-01

    During grain filling in C3 cereals, the shoot (particularly the flag leaf) and the ear are believed to play major roles as sources of assimilates. However, both the cost and the intrusive nature of most of the methodologies available to investigate this have prevented conclusive results being obtained. This study compared the carbon isotope composition (δ13C) in its natural abundance in mature kernels with the δ13C of the water-soluble fraction of the peduncle, glumes, and awns to assess the relative contribution of the shoot (understood as the whole set of photosynthetic organs below the peduncle) and ear to grain filling in a set of highly productive wheat lines from the International Maize and Wheat Improvement Center, Mexico, under good agronomic conditions. In overall terms, the contribution of the ear was greater in comparison with that of the shoot. The specific contribution of the flag leaf blade to grain filling was also assessed by comparing the δ13C of grains with the δ13C of the water-soluble fraction of the flag leaf and the awns. The contribution of the flag leaf was minor, ranging between 3 and 18%. Complementary analyses performed such as gas-exchange rates and the accumulated water-soluble carbohydrates in both organs and light intercepted by the canopy at different strata suggested that the ear has a photosynthetic capacity at least comparable to that of the flag leaf. In this sense, selection for a higher contribution of ear photosynthesis to grain yield in breeding programmes could be addressed with the use of stable isotopes. PMID:25053645

  14. Regional patterns of 15N natural abundance in forest ecosystems along a large transect in eastern China

    NASA Astrophysics Data System (ADS)

    Sheng, Wenping; Yu, Guirui; Fang, Huajun; Liu, Yingchun; Wang, Qiufeng; Chen, Zhi; Zhang, Li

    2014-02-01

    The regional determining factors underlying inter- and intra-site variation of 15N natural abundance in foliage, O horizon and mineral soil were investigated in eastern China.15N natural abundance values for these forest ecosystems were in the middle of the range of values previously found for global forest ecosystems. In contrast to commonly reported global patterns, temperate forest ecosystems were significantly more15N-enriched than tropical forest ecosystems, and foliage δ15N was negatively correlated with increasing mean annual temperature and net soil N mineralisation in eastern China. Tight N cycling in forest ecosystems and the use of atmospheric N deposition by trees might underlie the δ15N distribution patterns in eastern China. The existence of mycorrhizal fungi and root distribution profiles in the soil may also influence the15N natural abundance patterns in forest ecosystems of eastern China.

  15. IRMS detection of testosterone manipulated with 13C labeled standards in human urine by removing the labeled 13C.

    PubMed

    Wang, Jingzhu; Yang, Rui; Yang, Wenning; Liu, Xin; Xing, Yanyi; Xu, Youxuan

    2014-12-10

    Isotope ratio mass spectrometry (IRMS) is applied to confirm testosterone (T) abuse by determining the carbon isotope ratios (δ(13)C value). However, (13)C labeled standards can be used to control the δ(13)C value and produce manipulated T which cannot be detected by the current method. A method was explored to remove the (13)C labeled atom at C-3 from the molecule of androsterone (Andro), the metabolite of T in urine, to produce the resultant (A-nor-5α-androstane-2,17-dione, ANAD). The difference in δ(13)C values between Andro and ANAD (Δδ(13)CAndro-ANAD, ‰) would change significantly in case manipulated T is abused. Twenty-one volunteers administered T manipulated with different (13)C labeled standards. The collected urine samples were analyzed with the established method, and the maximum value of Δδ(13)CAndro-ANAD post ingestion ranged from 3.0‰ to 8.8‰. Based on the population reference, the cut-off value of Δδ(13)CAndro-ANAD for positive result was suggested as 1.2‰. The developed method could be used to detect T manipulated with 3-(13)C labeled standards. PMID:25441891

  16. Detection of inflammatory cell function using 13C magnetic resonance spectroscopy of hyperpolarized [6-13C]-arginine

    PubMed Central

    Najac, Chloé; Chaumeil, Myriam M.; Kohanbash, Gary; Guglielmetti, Caroline; Gordon, Jeremy W.; Okada, Hideho; Ronen, Sabrina M.

    2016-01-01

    Myeloid-derived suppressor cells (MDSCs) are highly prevalent inflammatory cells that play a key role in tumor development and are considered therapeutic targets. MDSCs promote tumor growth by blocking T-cell-mediated anti-tumoral immune response through depletion of arginine that is essential for T-cell proliferation. To deplete arginine, MDSCs express high levels of arginase, which catalyzes the breakdown of arginine into urea and ornithine. Here, we developed a new hyperpolarized 13C probe, [6-13C]-arginine, to image arginase activity. We show that [6-13C]-arginine can be hyperpolarized, and hyperpolarized [13C]-urea production from [6-13C]-arginine is linearly correlated with arginase concentration in vitro. Furthermore we show that we can detect a statistically significant increase in hyperpolarized [13C]-urea production in MDSCs when compared to control bone marrow cells. This increase was associated with an increase in intracellular arginase concentration detected using a spectrophotometric assay. Hyperpolarized [6-13C]-arginine could therefore serve to image tumoral MDSC function and more broadly M2-like macrophages. PMID:27507680

  17. Biosynthetic uniform 13C,15N-labelling of zervamicin IIB. Complete 13C and 15N NMR assignment.

    PubMed

    Ovchinnikova, Tatyana V; Shenkarev, Zakhar O; Yakimenko, Zoya A; Svishcheva, Natalia V; Tagaev, Andrey A; Skladnev, Dmitry A; Arseniev, Alexander S

    2003-01-01

    Zervamicin IIB is a member of the alpha-aminoisobutyric acid containing peptaibol antibiotics. A new procedure for the biosynthetic preparation of the uniformly 13C- and 15N-enriched peptaibol is described This compound was isolated from the biomass of the fungus-producer Emericellopsis salmosynnemata strain 336 IMI 58330 obtained upon cultivation in the totally 13C, 15N-labelled complete medium. To prepare such a medium the autolysed biomass and the exopolysaccharides of the obligate methylotrophic bacterium Methylobacillus flagellatus KT were used. This microorganism was grown in totally 13C, 15N-labelled minimal medium containing 13C-methanol and 15N-ammonium chloride as the only carbon and nitrogen sources. Preliminary NMR spectroscopic analysis indicated a high extent of isotope incorporation (> 90%) and led to the complete 13C- and 15N-NMR assignment including the stereospecific assignment of Aib residues methyl groups. The observed pattern of the structurally important secondary chemical shifts of 1H(alpha), 13C=O and 13C(alpha) agrees well with the previously determined structure of zervamicin IIB in methanol solution. PMID:14658801

  18. Field measurements of del13C in ecosystem respiration

    NASA Astrophysics Data System (ADS)

    van Asperen, Hella; Sabbatini, Simone; Nicolini, Giacomo; Warneke, Thorsten; Papale, Dario; Notholt, Justus

    2014-05-01

    Stable carbon isotope del13C-measurements are extensively used to study ecological and biogeochemical processes in ecosystems. Above terrestrial ecosystems, atmospheric del13C can vary largely due to photosynthetic fractionation. Photosynthetic processes prefer the uptake of the lighter isotope 12C (in CO2), thereby enriching the atmosphere in 13C and depleting the ecosystem carbon. At night, when ecosystem respiratory fluxes are dominant, 13C-depleted CO2 is respired and thereby depletes the atmospheric del13C-content. Different ecosystems and different parts of one ecosystem (type of plant, leaves, and roots) fractionate and respire with a different del13C-ratio signature. By determining the del13C-signature of ecosystem respiration in temporal and spatial scale, an analysis can be made of the composition of respiratory sources of the ecosystem. A field study at a dry cropland after harvest (province of Viterbo, Lazio, Italy) was performed in the summer of 2013. A FTIR (Fourier Transform Infrared Spectrometer) was set up to continuously measure CO2-, CH4-, N2O-, CO- and del13C-concentrations. The FTIR was connected to 2 different flux measurements systems: a Flux Gradient system (sampling every half hour at 1.3m and 4.2m) and 2 flux chambers (measured every hour), providing a continuous data set of the biosphere-atmosphere gas fluxes and of the gas concentrations at different heights. Keeling plot intercept values of respiratory CO2, measured by the Flux Gradient system at night, were determined to be between -25‰ and -20‰. Keeling plot intercept values of respiratory CO2, measured by the flux chamber system, varied between -24‰ and -29‰, and showed a clear diurnal pattern, suggesting different (dominant) respiratory processes between day and night.

  19. Direct uptake of organic carbon by grass roots and allocation in leaves and phytoliths: 13C labeling evidence

    NASA Astrophysics Data System (ADS)

    Alexandre, A.; Balesdent, J.; Cazevieille, P.; Chevassus-Rosset, C.; Signoret, P.; Mazur, J.-C.; Harutyunyan, A.; Doelsch, E.; Basile-Doelsch, I.; Miche, H.; Santos, G. M.

    2015-12-01

    In the rhizosphere, the uptake of low molecular weight carbon (C) and nitrogen (N) by plant roots has been well documented. While organic N uptake relatively to total uptake is important, organic C uptake is supposed to be low relatively to the plant's C budget. Recently, radiocarbon analyses demonstrated that a fraction of C from the soil was occluded in amorphous silica micrometric particles that precipitate in plant cells (phytoliths). Here, we investigated whether and in which extent organic C absorbed by grass roots, under the form of either intact amino acids (AAs) or microbial metabolites, can feed the organic C occluded in phytoliths. For this purpose we added 13C- and 15N-labeled AAs to the silicon-rich hydroponic solution of the grass Festuca arundinacea. The experiment was designed to prevent C leakage from the labeled nutritive solution to the chamber atmosphere. After 14 days of growth, the 13C and 15N enrichments (13C-excess and 15N-excess) in the roots, stems and leaves, and phytoliths, as well as the 13C-excess in AAs extracted from roots and stems and leaves, were quantified relatively to a control experiment in which no labelled AAs were added. The net uptake of 13C derived from the labeled AAs supplied to the nutritive solution (AA-13C) by Festuca arundinacea represented 4.5 % of the total AA-13C supply. AA-13C fixed in the plant represented only 0.13 % of total C. However, the experimental conditions may have underestimated the extent of the process under natural and field conditions. Previous studies showed that 15N and 13C can be absorbed by the roots in several organic and inorganic forms. In the present experiment, the fact that phenylalanine and methionine, that were supplied in high amount to the nutritive solution, were more 13C-enriched than other AAs in the roots and stems and leaves strongly suggested that part of AA-13C was absorbed and translocated in its original AA form. The concentration of AA-13C represented only 0.15 % of the

  20. Natural abundance nitrogen-15 nuclear magnetic resonance spectral studies on selected donors

    NASA Astrophysics Data System (ADS)

    Someswara Rao, N.; Babu Rao, G.; Murthy, B. N.; Das, M. Maria; Prabhakar, T.; Lalitha, M.

    2002-10-01

    The natural abundance 15N-NMR chemical shifts of selected aliphatic amines, 2-substituted pyridine type compounds, bialicyclic tertiary amines have been measured as a function of the nature of the solvent. In the case of cyclic aliphatic amines, like piperidine, morpholine, piperazine, thiomorpholine, the nitrogen is more shielded in concentrated solution compared to that in dilute solution whereas in the hydrogen bonding and protonating solvents there is a prominent deshielding. 2-Substituted pyridines studied can be further divided into four sub groups. The site of hydrogen bonding and protonation in 2-amino, 2-hydroxy and 2-mercapto pyridines have been conclusively proved from the 15N-NMR chemical shifts and the well-known tautomeric forms of the above compounds. Similarly in the case of 2-(2-thienyl)pyridine and 2-(3-thienyl)pyridine, the site of donation has been proved as the nitrogen of the pyridine ring in both the compounds. In a similar manner, the site of hydrogen bonding and protonation in two individual compounds 2-anilinopyridine and 2-(2-pyridyl)benzimidazole have also been established. Among the bialicyclic amines, 1,2-diazabicyclo[2.2.2]octane (DABCO) behaved differently from the other two compounds. In both 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), it was possible to show that N 1-nitrogen in both the compounds is the site of donation. The effect of the second donor site on the 15N-NMR chemical shift, the site of donation in the selected compounds and some typical compounds reported in literature have been presented and discussed.

  1. Natural abundance 17O nuclear magnetic resonance and computational modeling studies of lithium based liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Deng, Xuchu; Hu, Mary Y.; Wei, Xiaoliang; Wang, Wei; Chen, Zhong; Liu, Jun; Hu, Jian Zhi

    2015-07-01

    Natural abundance 17O NMR measurements were conducted on electrolyte solutions consisting of Li[CF3SO2NSO2CF3] (LiTFSI) dissolved in the solvents of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and their mixtures at various concentrations. It was observed that 17O chemical shifts of solvent molecules change with the concentration of LiTFSI. The chemical shift displacements of carbonyl oxygen are evidently greater than those of ethereal oxygen, strongly indicating that Li+ ion is coordinated with carbonyl oxygen rather than ethereal oxygen. To understand the detailed molecular interaction, computational modeling of 17O chemical shifts was carried out on proposed solvation structures. By comparing the predicted chemical shifts with the experimental values, it is found that a Li+ ion is coordinated with four double bond oxygen atoms from EC, PC, EMC and TFSI- anion. In the case of excessive amount of solvents of EC, PC and EMC the Li+ coordinated solvent molecules are undergoing quick exchange with bulk solvent molecules, resulting in average 17O chemical shifts. Several kinds of solvation structures are identified, where the proportion of each structure in the liquid electrolytes investigated depends on the concentration of LiTFSI.

  2. Probing surface hydrogen bonding and dynamics by natural abundance, multidimensional, 17O DNP-NMR spectroscopy

    DOE PAGESBeta

    Perras, Frederic A.; Chaudhary, Umesh; Slowing, Igor I.; Pruski, Marek

    2016-05-06

    Dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) spectroscopy is increasingly being used as a tool for the atomic-level characterization of surface sites. DNP surface-enhanced SSNMR spectroscopy of materials has, however, been limited to studying relatively receptive nuclei, and the particularly rare 17O nuclide, which is of great interest for materials science, has not been utilized. We demonstrate that advanced 17O SSNMR experiments can be performed on surface species at natural isotopic abundance using DNP. We use 17O DNP surface-enhanced 2D SSNMR to measure 17O{1H} HETCOR spectra as well as dipolar oscillations on a series of thermally treatedmore » mesoporous silica nanoparticle samples having different pore diameters. These experiments allow for a nonintrusive and unambiguous characterization of hydrogen bonding and dynamics at the surface of the material; no other single experiment can give such details about the interactions at the surface. Lastly, our data show that, upon drying, strongly hydrogen-bonded surface silanols, whose motions are greatly restricted by the interaction when compared to lone silanols, are selectively dehydroxylated.« less

  3. Natural Abundance 17O Nuclear Magnetic Resonance and Computational Modeling Studies of Lithium Based Liquid Electrolytes

    SciTech Connect

    Deng, Xuchu; Hu, Mary Y.; Wei, Xiaoliang; Wang, Wei; Chen, Zhong; Liu, Jun; Hu, Jian Z.

    2015-07-01

    Natural abundance 17O NMR measurements were conducted on electrolyte solutions consisting of Li[CF3SO2NSO2CF3] (LiTFSI) dissolved in the solvents of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), and their mixtures at various concentrations. It was observed that 17O chemical shifts of solvent molecules change with the concentration of LiTFSI. The chemical shift displacements of carbonyl oxygen are evidently greater than those of ethereal oxygen, strongly indicating that Li+ ion is coordinated with carbonyl oxygen rather than ethereal oxygen. To understand the detailed molecular interaction, computational modeling of 17O chemical shifts was carried out on proposed solvation structures. By comparing the predicted chemical shifts with the experimental values, it is found that a Li+ ion is coordinated with four double bond oxygen atoms from EC, PC, EMC and TFSI- anion. In the case of excessive amount of solvents of EC, PC and EMC the Li+ coordinated solvent molecules are undergoing quick exchange with bulk solvent molecules, resulting in average 17O chemical shifts. Several kinds of solvation structures are identified, where the proportion of each structure in the liquid electrolytes investigated depends on the concentration of LiTFSI.

  4. Natural abundance deuterium and 18-oxygen effects on the precision of the doubly labeled water method

    NASA Technical Reports Server (NTRS)

    Horvitz, M. A.; Schoeller, D. A.

    2001-01-01

    The doubly labeled water method for measuring total energy expenditure is subject to error from natural variations in the background 2H and 18O in body water. There is disagreement as to whether the variations in background abundances of the two stable isotopes covary and what relative doses of 2H and 18O minimize the impact of variation on the precision of the method. We have performed two studies to investigate the amount and covariance of the background variations. These were a study of urine collected weekly from eight subjects who remained in the Madison, WI locale for 6 wk and frequent urine samples from 14 subjects during round-trip travel to a locale > or = 500 miles from Madison, WI. Background variation in excess of analytical error was detected in six of the eight nontravelers, and covariance was demonstrated in four subjects. Background variation was detected in all 14 travelers, and covariance was demonstrated in 11 subjects. The median slopes of the regression lines of delta2H vs. delta18O were 6 and 7, respectively. Modeling indicated that 2H and 18O doses yielding a 6:1 ratio of final enrichments should minimize this error introduced to the doubly labeled water method.

  5. Application of Natural Isotopic Abundance ¹H-¹³C- and ¹H-¹⁵N-Correlated Two-Dimensional NMR for Evaluation of the Structure of Protein Therapeutics.

    PubMed

    Arbogast, Luke W; Brinson, Robert G; Marino, John P

    2016-01-01

    Methods for characterizing the higher-order structure of protein therapeutics are in great demand for establishing consistency in drug manufacturing, for detecting drug product variations resulting from modifications in the manufacturing process, and for comparing a biosimilar to an innovator reference product. In principle, solution NMR can provide a robust approach for characterization of the conformation(s) of protein therapeutics in formulation at atomic resolution. However, molecular weight limitations and the perceived need for stable isotope labeling have to date limited its practical applications in the biopharmaceutical industry. Advances in NMR magnet and console technologies, cryogenically cooled probes, and new rapid acquisition methodologies, particularly selective optimized flip-angle short transient pulse schemes and nonuniform sampling, have greatly ameliorated these limitations. Here, we describe experimental methods for the collection and analysis of 2D (1)H(N)-(15)N-amide- and (1)H-(13)C-methyl-correlated spectra applied to protein drug products at natural isotopic abundance, including representatives from the rapidly growing class of monoclonal antibody (mAb) therapeutics. Practical aspects of experimental setup and data acquisition for both standard and rapid acquisition NMR techniques are described. Furthermore, strategies for the statistical comparison of 2D (1)H(N)-(15)N-amide- and (1)H-(13)C-methyl-correlated spectra are detailed. PMID:26791974

  6. Relation of desert pupfish abundance to selected environmental variables in natural and manmade habitats in the Salton Sea basin

    USGS Publications Warehouse

    Martin, B.A.; Saiki, M.K.

    2005-01-01

    We assessed the relation between abundance of desert pupfish, Cyprinodon macularius, and selected biological and physicochemical variables in natural and manmade habitats within the Salton Sea Basin. Field sampling in a natural tributary, Salt Creek, and three agricultural drains captured eight species including pupfish (1.1% of the total catch), the only native species encountered. According to Bray-Curtis resemblance functions, fish species assemblages differed mostly between Salt Creek and the drains (i.e., the three drains had relatively similar species assemblages). Pupfish numbers and environmental variables varied among sites and sample periods. Canonical correlation showed that pupfish abundance was positively correlated with abundance of western mosquitofish, Gambusia affinis, and negatively correlated with abundance of porthole livebearers, Poeciliopsis gracilis, tilapias (Sarotherodon mossambica and Tilapia zillii), longjaw mudsuckers, Gillichthys mirabilis, and mollies (Poecilia latipinnaandPoecilia mexicana). In addition, pupfish abundance was positively correlated with cover, pH, and salinity, and negatively correlated with sediment factor (a measure of sediment grain size) and dissolved oxygen. Pupfish abundance was generally highest in habitats where water quality extremes (especially high pH and salinity, and low dissolved oxygen) seemingly limited the occurrence of nonnative fishes. This study also documented evidence of predation by mudsuckers on pupfish. These findings support the contention of many resource managers that pupfish populations are adversely influenced by ecological interactions with nonnative fishes. ?? Springer 2005.

  7. Elevated Bacterial Abundance in Laboratory-Grown and Naturally Occurring Frost Flowers Under Late Winter Conditions

    NASA Astrophysics Data System (ADS)

    Bowman, J. S.; Deming, J. W.

    2009-12-01

    Sea ice has been identified as an important microbial habitat, with bacteria and other microbes concentrated in the brine inclusions between ice crystals. Frost flowers, thought to draw brine from underlying sea ice, have not been characterized from a microbial standpoint. To test whether frost flowers serve as an upward vector of bacteria contained within sea ice brines we grew frost flowers in a freezer laboratory (air temperature of -21°C) from saline water spiked with the mesophilic (and thus passive under experimental conditions) bacterium Halomonas pacifica. Salinity of melted samples was measured and bacterial abundance determined by epifluorescent microscopy. Bacterial counts scaled to ice-melt volume averaged 2.82 x 106 ml-1 for frost flowers, compared to 9.47 x 105 ml-1 for underlying ice (3 x higher). Bacterial counts also correlated significantly with salinity (maximum value of 62.5 psu) for frost flowers, brine skim, and ice (df = 17, r = 0.59, p < 0.0001). Segregation coefficients were calculated to describe the efficiency of transport of both cells and salt from the starting solution into frost flowers. From these coefficients an enrichment index was calculated to test for bacterial concentration into frost flowers at a different rate than salt. Analysis with a Student’s T-test (df = 24, t = 0.306, p = .76) indicated that cells and salt were not transported into frost flowers with a significantly different efficiency. To test these findings in the field we then collected frost flowers (and related samples) from new sea ice near Barrow, Alaska in April 2009. Bacterial counts were significantly elevated (again, a 3-fold increase) in natural frost flowers (mean = 2.73 x 105 ml-1) compared to underlying sea ice (mean = 8.46 x 104 cells ml-1). For all field samples collected (frost flowers, underlying brine skim and sea ice, as well as snow), bacterial abundance correlated significantly with salinity (maximum value 124 psu, df = 40, r = 0.60, p < 0

  8. Formation and abundance of doubly-substituted methane isotopologues ( 13CH 3D) in natural gas systems

    NASA Astrophysics Data System (ADS)

    Ma, Qisheng; Wu, Sheng; Tang, Yongchun

    2008-11-01

    Formation of the Carbon-13 ( 13C) and deuterium (D) doubly-substituted methane isotopologues ( 13CH 3D) in natural gases is studied utilizing both first-principle quantum mechanism molecular calculation and direct FTIR laboratorial measurements of specifically synthesized high isotope concentration methane gas. For 13CH 3D, the symmetrically breathing mode A0 emerges as IR-detectable attributed to the molecular symmetry lowering to C3v from Td of the non-isotopic methane (CH 4), along with a large vibrational frequency shift from ˜3000 to ˜2250 cm -1. Our studies also indicate that the concentration of 13CH 3D is dependent on the environmental temperature through isotope exchanges among methane isotopologues; and the Gibbs' Free Energy difference due to Quantum Mechanics Zero-Point vibrational motions has the major contribution to this temperature dependency. Potential geologic applications of the 13CH 3D measurement to natural gas exploration and assessments are also discussed. In order to detect the 13CH 3D concentration change of each 50 °C in the natural gas system, a 10 -9 resolution is desirable. Such a measurement could provide important add-on information to distinguish natural gas origin and distribution.

  9. Determination of glucan phosphorylation using heteronuclear 1H, 13C double and 1H, 13C, 31P triple-resonance NMR spectra.

    PubMed

    Schmieder, Peter; Nitschke, Felix; Steup, Martin; Mallow, Keven; Specker, Edgar

    2013-10-01

    Phosphorylation and dephosphorylation of starch and glycogen are important for their physicochemical properties and also their physiological functions. It is therefore desirable to reliably determine the phosphorylation sites. Heteronuclear multidimensional NMR-spectroscopy is in principle a straightforward analytical approach even for complex carbohydrate molecules. With heterogeneous samples from natural sources, however, the task becomes more difficult because a full assignment of the resonances of the carbohydrates is impossible to obtain. Here, we show that the combination of heteronuclear (1) H,(13) C and (1) H,(13) C,(31) P techniques and information derived from spectra of a set of reference compounds can lead to an unambiguous determination of the phosphorylation sites even in heterogeneous samples. PMID:23913630

  10. The Determination of the Natural Abundance of the Isotopes of Chlorine: An Introductory Experiment in Mass Spectrometry.

    ERIC Educational Resources Information Center

    O'Malley, Rebecca M.

    1982-01-01

    Describes a laboratory experiment which introduces basic principles and experimental techniques of mass spectrometry for fourth year undergraduate (B.Sc.) students. Laboratory procedures, background information, and discussion of results are provided for the experiment in which the natural isotopic abundance of chlorine is determined. (Author/JN)

  11. Seasonal variation in natural abundance of 2H and 18O in urine samples from rural Nigeria

    PubMed Central

    Dugas, Lara R.; Brieger, William; Tayo, Bamidele O.; Alabi, Tunrayo; Schoeller, Dale A.; Luke, Amy

    2015-01-01

    The doubly labeled water (DLW) method is used to measure free-living energy expenditure in humans. Inherent to this technique is the assumption that natural abundances of stable isotopes 2H and 18O in body water remain constant over the course of the measurement period and after elimination of the loading dose of DLW will return to the same predose level. To determine variability in the natural abundances of 2H and 18O in humans living in a region with seasonal shifts in rain patterns and sources of drinking water, over the course of 12 mo we collected weekly urine samples from four individuals living in southwest Nigeria as well as samples of their drinking water. From ongoing regional studies of hypertension, obesity, and energy expenditure, we estimated average water turnover rate, urine volumes, and sodium and potassium excretion. Results suggest that 2H and 18O in urine, mean concentrations of urinary sodium and potassium, urine volume, and total body turnover differed significantly from dry to rainy season. Additionally, seasonal weather variables (mean monthly maximum temperatures, total monthly rainfall, and minimum relative humidity) were all significantly associated with natural abundances in urine. No seasonal difference was observed in drinking water samples. Findings suggest that natural abundances in urine may not remain constant as assumed, and studies incorporating DLW measurements across the transition of seasons should interpret results with caution unless appropriate doses of the tracers are used. PMID:25977450

  12. Natural abundance deuterium nuclear magnetic resonance spectroscopy: Study of the biosynthesis of monoterpenes

    SciTech Connect

    Leopold, M.F.

    1990-01-01

    Deuterium NMR spectroscopy at natural abundance (D NMR-na) is a new technique for exploring the biosynthesis of small molecules such as monoterpenes. The analysis of relative site-specific deuterium integration values is an effective means of measuring isotope effects, and examining the regio- and stereochemistry of biosynthetic reactions. The deuterium integration values of linalyl acetate and limonene isolated from the same source were consistent and showed that proton abstraction from the postulated {alpha}-terpinyl cation intermediate to form limonene is regioselective from the methyl derived from the Cs methyl of the precursor, geranyl diphosphate. This regiochemistry was observed in limonene samples from different sources and the measured primary kinetic isotope effect ranged from 0.25 to in excess of 100 (no deuterium was removed within experimental error). Various {alpha}- and {beta}-pinene samples were isolated and D NMR-na analysis showed evidence of isotopically sensitive partitioning of the pinylcation in the formation of these products. This spectral analysis supported published radiolabeling studies but did not require synthesis of substrates or enzyme purification. The formation of 3-carene occurs without isomerization of the double bond which was previously postulated. The olefinic deuterium of the bicyclic compound was traced to the depleted deuterium at C{sub 2} of isopentyl diphosphate by D NMR-na data and this supported unpublished radiolabeling studies. Study of irregular monoterpenes, chrysanthemyl acetate and lyratyl acetate, showed partitioning of dimethylallyl diphosphate (DMAPP) by chrysanthemyl cyclase. The {alpha}-secondary kinetic isotope effect of 1.06-1.12, obtained from relative deuterium integration values, suggested that S{sub N}1 ionization of one molecule of DMAPP is the first step in the condensation reaction.

  13. A robust method for ammonium nitrogen isotopic analysis in freshwater and seawater at natural abundance levels

    NASA Astrophysics Data System (ADS)

    Zhang, L.; Altabet, M. A.; Wu, T.; Hadas, O.

    2006-12-01

    Natural ammonium N isotopic abundance has been increasingly used in studies of marine and freshwater biogeochemistry. However, current methods are time-consuming, subject to interference from DON, and not reliable at low concentrations. Our new method for determining the δ15N of ammonium overcomes these difficulties by employing the oxidation of ammonium to nitrite followed by conversion of nitrite to nitrous oxide. In the first step, ammonium is quantitatively oxidized by hypobromite at pH~12. After the addition of sodium arsenite to consume excess hypobromite, yield is verified by colorimetric NO2-measurement using sulfanilamide and naphthyl ethylenediamine (NED). Nitrite is further reduced to N2O by a 1:1 sodium azide and acetic acid buffer solution using previously established procedures. Buffer concentration can be varied according to sample matrix to ensure that a reaction pH between 2 and 4 is reached. The product nitrous oxide is then isotopically analyzed using a continuous flow purge and cryogenic trap system coupled to an isotope ratio mass spectrometer. Reliable δ15N values (±0.31‰) are obtained over a concentration range of 0.5 μM to 20 μM using 20 ml volumes of either fresh or seawater samples. Reagent blanks are very low, about 0.05 μM. There is no interference from any of the nitrogen containing compounds tested except short chain aliphatic amino acid (i.e. glycine) which typically are not present at sufficiently high environmental concentrations to pose a problem.

  14. Chemical method for nitrogen isotopic analysis of ammonium at natural abundance.

    PubMed

    Liu, Dongwei; Fang, Yunting; Tu, Ying; Pan, Yuepeng

    2014-04-15

    We report a new chemical method to determine the (15)N natural abundance (δ(15)N) for ammonium (NH4(+)) in freshwater (e.g., precipitation) and soil KCl extract. This method is based on the isotopic analysis of nitrous oxide (N2O). Ammonium is initially oxidized to nitrite (NO2(-)) by hypobromite (BrO(-)) using previously established procedures. NO2(-) is then quantitatively converted into N2O by hydroxylamine (NH2OH) under strongly acid conditions. The produced N2O is analyzed by a commercially available purge and cryogenic trap system coupled to an isotope ratio mass spectrometer (PT-IRMS). On the basis of a typical analysis size of 4 mL, the standard deviation of δ(15)N measurements is less than 0.3‰ and often better than 0.1‰ (3 to 5 replicates). Compared to previous methods, the technique here has several advantages and the potential to be used as a routine method for (15)N/(14)N analysis of NH4(+): (1) substantially simplified preparation procedures and reduced preparation time particularly compared to the methods in which diffusion or distillation is involved since all reactions occur in the same vial and separation of NH4(+) from solution is not required; (2) more suitability for low volume samples including those with low N concentration, having a blank size of 0.6 to 2 nmol; (3) elimination of the use of extremely toxic reagents (e.g., HN3) and/or the use of specialized denitrifying bacterial cultures which may be impractical for many laboratories. PMID:24654992

  15. Variation of delta13C in Aegiceras corniculatum seedling induced by cadmium application.

    PubMed

    Wei, Lili; Yan, Chongling; Wu, Guirong; Guo, Xiaoyin; Ye, Binbin

    2008-08-01

    To test whether the values of delta13C in mangrove plants are affected by Cd application, the seedlings of Aegiceras corniculatum, a dominant mangrove species, were cultured in soil supplied with CdCl2 solution at the concentration of 0, 0.5, 2.5, 5, 20, 30 and 50 CdCl2 mg/kg wet soils. Plants were grown in 10 replicate pots with 5 propagules each. After 5 months of Cd exposure, three pots contained 15 seedlings with average shoot heights were selected for each treatment. Leaves and roots of seedling were sampled respectively and analyzed for delta(13)C. Growth traits (fresh weight, shoot height and root length), total chlorophyll content, and Cd concentrations in leaf, root and dry soil were determined. After 5 months of the seedling growth, the concentrations of Cd in dry soil were 0.47, 0.83, 2.77, 4.54, 18.89, 29.79 and 47.35 mg/kg respectively. The values of delta13C in roots and leaves were affected to some extent by Cd application. Although root delta(13)C showed more sensitive to Cd compared with leaves, the values of delta13C in roots were not significantly affected by Cd until Cd level higher than 29.78 mg/kg which was not expected to exist in natural environments. Minor variation in delta13C values observed in roots and leaves was likely due to limited Cd uptake by seedlings and subsequent lack of negative impacts on photosynthesis. PMID:18386175

  16. The 13C/2H-glucose test for determination of small intestinal lactase activity.

    PubMed

    Vonk, R J; Stellaard, F; Priebe, M G; Koetse, H A; Hagedoorn, R E; De Bruijn, S; Elzinga, H; Lenoir-Wijnkoop, I; Antoine, J M

    2001-03-01

    To diagnose hypolactasia, determination of lactase enzyme activity in small intestinal biopsy material is considered to be the golden standard. Because of its strongly invasive character and the sampling problems, alternative methods have been looked for. We analysed the 13C-glucose response in serum after consumption of 25 g of naturally enriched 13C-lactose. As an internal standard, 0.5 g of 2H-glucose was added and the 2H-glucose response in serum was measured simultaneously. The studies were performed in healthy volunteers with a background of genetically determined lactase nonpersistence (n = 12; low lactase activity) and lactase persistence (n = 27; high lactase activity). The results were compared with those of the lactose hydrogen breath test, the lactose 13CO2 breath test and the previously described 13C-lactose digestion test. After consumption of 13C-lactose and 2H-glucose, the mean ratio 13C-glucose/2H-glucose concentration in serum at 45-75 min was 0.26 +/- 0.09 in the low lactase activity group and 0.93 +/- 0.17 in the high lactase activity group (P < 0.01). Threshold of the ratio between digesters and maldigesters was calculated as 0.46. Accuracy of the new test was superior to all other tests. We conclude that the 13C/2H-glucose test has the potential of determining the small intestinal lactase activity in vivo and of estimating the amount of lactose which is digested in the small intestine. PMID:11264650

  17. Transport and imaging of brute-force (13)C hyperpolarization.

    PubMed

    Hirsch, Matthew L; Smith, Bryce A; Mattingly, Mark; Goloshevsky, Artem G; Rosay, Melanie; Kempf, James G

    2015-12-01

    We demonstrate transport of hyperpolarized frozen 1-(13)C pyruvic acid from its site of production to a nearby facility, where a time series of (13)C images was acquired from the aqueous dissolution product. Transportability is tied to the hyperpolarization (HP) method we employ, which omits radical electron species used in other approaches that would otherwise relax away the HP before reaching the imaging center. In particular, we attained (13)C HP by 'brute-force', i.e., using only low temperature and high-field (e.g., T<∼2K and B∼14T) to pre-polarize protons to a large Boltzmann value (∼0.4% (1)H polarization). After polarizing the neat, frozen sample, ejection quickly (<1s) passed it through a low field (B<100G) to establish the (1)H pre-polarization spin temperature on (13)C via the process known as low-field thermal mixing (yielding ∼0.1% (13)C polarization). By avoiding polarization agents (a.k.a. relaxation agents) that are needed to hyperpolarize by the competing method of dissolution dynamic nuclear polarization (d-DNP), the (13)C relaxation time was sufficient to transport the sample for ∼10min before finally dissolving in warm water and obtaining a (13)C image of the hyperpolarized, dilute, aqueous product (∼0.01% (13)C polarization, a >100-fold gain over thermal signals in the 1T scanner). An annealing step, prior to polarizing the sample, was also key for increasing T1∼30-fold during transport. In that time, HP was maintained using only modest cryogenics and field (T∼60K and B=1.3T), for T1((13)C) near 5min. Much greater time and distance (with much smaller losses) may be covered using more-complete annealing and only slight improvements on transport conditions (e.g., yielding T1∼5h at 30K, 2T), whereas even intercity transfer is possible (T1>20h) at reasonable conditions of 6K and 2T. Finally, it is possible to increase the overall enhancement near d-DNP levels (i.e., 10(2)-fold more) by polarizing below 100mK, where nanoparticle

  18. Transport and imaging of brute-force 13C hyperpolarization

    NASA Astrophysics Data System (ADS)

    Hirsch, Matthew L.; Smith, Bryce A.; Mattingly, Mark; Goloshevsky, Artem G.; Rosay, Melanie; Kempf, James G.

    2015-12-01

    We demonstrate transport of hyperpolarized frozen 1-13C pyruvic acid from its site of production to a nearby facility, where a time series of 13C images was acquired from the aqueous dissolution product. Transportability is tied to the hyperpolarization (HP) method we employ, which omits radical electron species used in other approaches that would otherwise relax away the HP before reaching the imaging center. In particular, we attained 13C HP by 'brute-force', i.e., using only low temperature and high-field (e.g., T < ∼2 K and B ∼ 14 T) to pre-polarize protons to a large Boltzmann value (∼0.4% 1H polarization). After polarizing the neat, frozen sample, ejection quickly (<1 s) passed it through a low field (B < 100 G) to establish the 1H pre-polarization spin temperature on 13C via the process known as low-field thermal mixing (yielding ∼0.1% 13C polarization). By avoiding polarization agents (a.k.a. relaxation agents) that are needed to hyperpolarize by the competing method of dissolution dynamic nuclear polarization (d-DNP), the 13C relaxation time was sufficient to transport the sample for ∼10 min before finally dissolving in warm water and obtaining a 13C image of the hyperpolarized, dilute, aqueous product (∼0.01% 13C polarization, a >100-fold gain over thermal signals in the 1 T scanner). An annealing step, prior to polarizing the sample, was also key for increasing T1 ∼ 30-fold during transport. In that time, HP was maintained using only modest cryogenics and field (T ∼ 60 K and B = 1.3 T), for T1(13C) near 5 min. Much greater time and distance (with much smaller losses) may be covered using more-complete annealing and only slight improvements on transport conditions (e.g., yielding T1 ∼ 5 h at 30 K, 2 T), whereas even intercity transfer is possible (T1 > 20 h) at reasonable conditions of 6 K and 2 T. Finally, it is possible to increase the overall enhancement near d-DNP levels (i.e., 102-fold more) by polarizing below 100 mK, where

  19. Analysis of carbon and nitrogen co-metabolism in yeast by ultrahigh-resolution mass spectrometry applying 13C- and 15N-labeled substrates simultaneously.

    PubMed

    Blank, Lars M; Desphande, Rahul R; Schmid, Andreas; Hayen, Heiko

    2012-06-01

    Alternative metabolic pathways inside a cell can be deduced using stable isotopically labeled substrates. One prerequisite is accurate measurement of the labeling pattern of targeted metabolites. Experiments are generally limited to the use of single-element isotopes, mainly (13)C. Here, we demonstrate the application of direct infusion nanospray, ultrahigh-resolution Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) for metabolic studies using differently labeled elemental isotopes simultaneously--i.e., (13)C and (15)N--in amino acids of a total protein hydrolysate. The optimized strategy for the analysis of metabolism by a hybrid linear ion trap-FTICR-MS comprises the collection of multiple adjacent selected ion monitoring scans. By limiting both the width of the mass range and the number of ions entering the ICR cell with automated gain control, sensitive measurements of isotopologue distribution were possible without compromising mass accuracy and isotope intensity mapping. The required mass-resolving power of more than 60,000 is only achievable on a routine basis by FTICR and Orbitrap mass spectrometers. Evaluation of the method was carried out by comparison of the experimental data to the natural isotope abundances of selected amino acids and by comparison to GC/MS results obtained from a labeling experiment with (13)C-labeled glucose. The developed method was used to shed light on the complexity of the yeast Saccharomyces cerevisiae carbon-nitrogen co-metabolism by administering both (13)C-labeled glucose and (15)N-labeled alanine. The results indicate that not only glutamate but also alanine acts as an amino donor during alanine and valine synthesis. Metabolic studies using FTICR-MS can exploit new possibilities by the use of multiple-labeled elemental isotopes. PMID:22543713

  20. A 13C-NMR study of azacryptand complexes.

    PubMed

    Wild, Aljoscha A C; Fennell, Kevin; Morgan, Grace G; Hewage, Chandralal M; Malthouse, J Paul G

    2014-09-28

    An azacryptand has been solubilised in aqueous media containing 50% (v/v) dimethyl sulphoxide. (13)C-NMR has been used to determine how the azacryptand is affected by zinc binding at pH 10. Using (13)C-NMR and (13)C-enriched bicarbonate we have been able to observe the formation of 4 different carbamate derivatives of the azacryptand at pH 10. The azacryptand was shown to solubilise zinc or cadmium at alkaline pHs. Two moles of zinc are bound per mole of azacryptand and this complex binds 1 mole of carbonate. By replacing the zinc with cadmium-113 we have shown that the (13)C-NMR signal of the (13)C-enriched carbon of the bound carbonate is split into two triplets at 2.2 °C. This shows that two cadmium complexes are formed and in each of these complexes the carbonate group is bound by two magnetically equivalent metal ions. It also demonstrates that these cadmium complexes are not in fast exchange. From temperature studies we show that in the zinc complexes both complexes are in fast exchange with each other but are in slow exchange with free bicarbonate. HOESY is used to determine the position of the carbonate carbon in the complex. The solution and crystal structures of the zinc-carbonate-azacryptand complexes are compared. PMID:25091182

  1. Synthesis and applications of {sup 13}C glycerol

    SciTech Connect

    Stocking, E.; Khalsa, O.; Martinez, R.A.; Silks, L.A. III

    1994-12-01

    Due in part to the use of labeled glycerol for the {sup 13}C enrichment of biomolecules, we are currently developing new synthetic routes to various isotopomers of glycerol. Judging from our experience, traditional methods of glycerol synthesis are not easily adapted for isotopic enrichment and/or have poor overall yields (12 to 15%). Furthermore, the use of glycerol for enrichment can be prohibitively expensive and its availability is limited by the level of demand. We are presently developing a short de novo synthesis of glycerol from carbon dioxide ({approximately}53% overall yield for four steps) and are examining the feasibility of synthesizing site-specific {sup 13}C-labeled glycerol and dihydroxyacetone (DHA) from labeled methanol and carbon dioxide. One application of {sup 13}C glycerol we have examined is enzymatic conversion of glycerol to glyceraldehyde-3-monophosphate or dihydroxyacetone monophosphate (DHAP) with yields ranging from 25 to 50% (as determined by NMR spectroscopy). We are also pursuing the chemical conversion of {sup 13}C-labeled DHA to DHAP. We are especially interested in {sup 13}C-labeled DHAP because we are investigating its use as a chemo-enzymatic precursor for both labeled 2-deoxyribose and 2-deoxyribonucleic acids.

  2. A scientific workflow framework for (13)C metabolic flux analysis.

    PubMed

    Dalman, Tolga; Wiechert, Wolfgang; Nöh, Katharina

    2016-08-20

    Metabolic flux analysis (MFA) with (13)C labeling data is a high-precision technique to quantify intracellular reaction rates (fluxes). One of the major challenges of (13)C MFA is the interactivity of the computational workflow according to which the fluxes are determined from the input data (metabolic network model, labeling data, and physiological rates). Here, the workflow assembly is inevitably determined by the scientist who has to consider interacting biological, experimental, and computational aspects. Decision-making is context dependent and requires expertise, rendering an automated evaluation process hardly possible. Here, we present a scientific workflow framework (SWF) for creating, executing, and controlling on demand (13)C MFA workflows. (13)C MFA-specific tools and libraries, such as the high-performance simulation toolbox 13CFLUX2, are wrapped as web services and thereby integrated into a service-oriented architecture. Besides workflow steering, the SWF features transparent provenance collection and enables full flexibility for ad hoc scripting solutions. To handle compute-intensive tasks, cloud computing is supported. We demonstrate how the challenges posed by (13)C MFA workflows can be solved with our approach on the basis of two proof-of-concept use cases. PMID:26721184

  3. 13C NMR spectroscopy applications to brain energy metabolism

    PubMed Central

    Rodrigues, Tiago B.; Valette, Julien; Bouzier-Sore, Anne-Karine

    2013-01-01

    13C nuclear magnetic resonance (NMR) spectroscopy is the method of choice for studying brain metabolism. Indeed, the most convincing data obtained to decipher metabolic exchanges between neurons and astrocytes have been obtained using this technique, thus illustrating its power. It may be difficult for non-specialists, however, to grasp thefull implication of data presented in articles written by spectroscopists. The aim of the review is, therefore, to provide a fundamental understanding of this topic to facilitate the non-specialists in their reading of this literature. In the first part of this review, we present the metabolic fate of 13C-labeled substrates in the brain in a detailed way, including an overview of some general neurochemical principles. We also address and compare the various spectroscopic strategies that can be used to study brain metabolism. Then, we provide an overview of the 13C NMR experiments performed to analyze both intracellular and intercellular metabolic fluxes. More particularly, the role of lactate as a potential energy substrate for neurons is discussed in the light of 13C NMR data. Finally, new perspectives and applications offered by 13C hyperpolarization are described. PMID:24367329

  4. Complete assignment of (1)H and (13)C NMR spectra of standard neo-iota-carrabiose oligosaccharides.

    PubMed

    Jouanneau, Diane; Boulenguer, Patrick; Mazoyer, Jacques; Helbert, William

    2010-02-26

    Standard Eucheuma denticulatum iota-carrageenan was degraded with the Alteromonas fortis iota-carrageenase. The most abundant products, the neo-iota-carratetraose and neo-iota-carrahexaose were purified by permeation gel chromatography, and their corresponding (1)H and (13)C NMR spectra were fully assigned. PMID:20038459

  5. The Rotational Spectrum of Singly and Doubly 13C-SUBSTITUTED Dimethylether

    NASA Astrophysics Data System (ADS)

    Koerber, Monika; Endres, Christian P.; Lewen, Frank; Giesen, Thomas F.; Schlemmer, Stephan; Pohl, Roland; Klein, Axel

    2010-06-01

    Dimethylether (DME) is a nearly prolate asymmetric top with two internal rotors (methyl groups) which undergo periodic large amplitude motions and show a complicated torsional splitting of each rotational energy level. Due to its complex spectrum and its high abundance in hot cores such as Orion KL or Sagittarius B2 at temperatures exceeding 100 K, DME is very prominent in astronomical line surveys and contributes to spectral line confusion of such sources. The interpretation of astronomical observations therefore depends on the knowledge of accurate rest frequencies and reliable intensities. Precise predictions for the ground state of DME's main isotopologue are now available up to 2.1 THz In contrast, very little is known about 13C-substituted DME. Only a few data are available on singly 13C-substituted DME, 12CH_3O13CH_3. However, no data are available on doubly 13C-substituted DME, (13CH_3)_2O, yet. While in (13CH_3)_2O the two internal rotating methyl groups are equivalent and the splitting of rotational energy levels into four substates is comparable to the main isotopologue, singly 13C-substituted DME has two non-equivalent internal rotors resulting in torsional splitting of rotational energy levels into five substates. The purpose of our new laboratory measurements is to extend the knowledge on the astrophysically relevant species 12CH_3O13CH_3. To analyze the complicated spectrum resulting from a 13C-enriched sample of DME, containing all different 13C-substituted species as well as the main isotopologue, also precise data on doubly 13C-substituted DME are inevitable. We performed measurements in the frequency region 35-120 GHz using an all solid state spectrometer. Rotational as well as torsional parameters have been obtained for (13CH_3)_2O as well as 12CH_3O13CH_3 by fitting the assigned transitions to an effective rotational Hamiltonian introduced by Peter Groner. C. Comito et al., Astrophys. J. Suppl. Ser. 156, 127-167 (2005) C. P. Endres et al

  6. Diethers enriched in 13C suggest carbon-limitation at the Lost City Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Bradley, A. S.; Hayes, J. M.; Summons, R. E.

    2004-12-01

    Active and inactive carbonate vent structures from the Lost City Hydrothermal Field (LCHF) contain up to 0.6% organic carbon including diverse lipids. Values of δ 13C for total organic carbon (TOC) range from -18.7‰ vs. VPDB at the active, high-temperature vent known as "The Beehive" (90° C), to -3.1‰ at Marker 7 (active, 70° C). Samples with relatively high levels of 13C also contained high amounts of isoprenoidal and nonisoprenoidal diethers. Samples more depleted in 13C lacked or contained low amounts of these diethers. The correlation between high 13C and abundant diethers is supported by compound-specific isotopic analyses. Archaeal and bacterial diethers are enriched in 13C relative to photosynthetically derived marine carbon. The biomarkers sn-2 hydroxyarchaeol, sn-3 hydroxyarchaeol, and dihydroxyarchaeol - considered diagnostic for methane-cycling archaea - had δ values ranging from -8.5 to +4.8‰ . Phylogenetic data confirms the presence at these vents of a single group of methanogens, related to the Methanosarcinales (Schrenk et al., 2004). Diethers with non-isoprenoidal alkyl chains are also present, are of presumed bacterial origin, and may indicated the presence of sulfate-reducing bacteria. Values of δ for these compounds range from -7.3 to +1.0‰ . At the Beehive vent, diether lipids are absent and the TOC is depleted in 13C. Coexistence of isotopically similar hydroxyarchaeols and nonisoprenoidal glycerol diethers is typical of marine, cold-seep environments at which concentrations of H2 are low and methane is oxidized anaerobically. At the LCHF, however, concentrations of H2 in pore waters reach 15 mM (Proskurowski et al., 2003). This H2, produced by serpentinization reactions, drives production (rather than oxidation) of methane. Simultaneously, sulfate-reducing bacteria can flourish as carbon-fixing autotrophs. Under such conditions, carbon may be the limiting substrate, its nearly complete consumption accounting for the enrichment of

  7. Climatic Control on Plant and Soil δ13C along an Altitudinal Transect of Lushan Mountain in Subtropical China: Characteristics and Interpretation of Soil Carbon Dynamics

    PubMed Central

    Du, Baoming; Liu, Chunjiang; Kang, Hongzhang; Zhu, Penghua; Yin, Shan; Shen, Guangrong; Hou, Jingli; Ilvesniemi, Hannu

    2014-01-01

    Decreasing temperature and increasing precipitation along altitude gradients are typical mountain climate in subtropical China. In such a climate regime, identifying the patterns of the C stable isotope composition (δ13C) in plants and soils and their relations to the context of climate change is essential. In this study, the patterns of δ13C variation were investigated for tree leaves, litters, and soils in the natural secondary forests at four altitudes (219, 405, 780, and 1268 m a.s.l.) in Lushan Mountain, central subtropical China. For the dominant trees, both leaf and leaf-litter δ13C decreased as altitude increased from low to high altitude, whereas surface soil δ13C increased. The lower leaf δ13C at high altitudes was associated with the high moisture-related discrimination, while the high soil δ13C is attributed to the low temperature-induced decay. At each altitude, soil δ13C became enriched with soil depth. Soil δ13C increased with soil C concentrations and altitude, but decreased with soil depth. A negative relationship was also found between O-alkyl C and δ13C in litter and soil, whereas a positive relationship was observed between aromatic C and δ13C. Lower temperature and higher moisture at high altitudes are the predominant control factors of δ13C variation in plants and soils. These results help understand C dynamics in the context of global warming. PMID:24466099

  8. The Titan 14N/ 15N and 12C/ 13C isotopic ratios in HCN from Cassini/CIRS

    NASA Astrophysics Data System (ADS)

    Vinatier, Sandrine; Bézard, Bruno; Nixon, Conor A.

    2007-11-01

    We report the detection of H 13CN and HC 15N in mid-infrared spectra recorded by the Composite Infrared Spectrometer (CIRS) aboard Cassini, along with the determination of the 12C/ 13C and 14N/ 15N isotopic ratios. We analyzed two sets of limb spectra recorded near 13-15° S (Tb flyby) and 83° N (T4 flyby) at 0.5 cm -1 resolution. The spectral range 1210-1310 cm -1 was used to retrieve the temperature profile in the range 145-490 km at 13° S and 165-300 km at 83° N. These two temperature profiles were then incorporated in the atmospheric model to retrieve the abundance profile of H 12C 14N, H 13CN and HC 15N from their bands at 713, 706 and 711 cm -1, respectively. The HCN abundance profile was retrieved in the range 90-460 km at 15° S and 165-305 km at 83° N. There is no evidence for vertical variations of the isotopic ratios. Constraining the isotopic abundance profiles to be proportional to the HCN one, we find C12/C13=89-18+22 at 15° S, and 68-12+16 at 83° N, two values that are statistically consistent. A combination of these results yields a 12C/ 13C value equal to 75±12. This global result, as well as the 15° S one, envelop the value in Titan's methane ( 82.3±1) [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784] measured at 10° S and is slightly lower than the terrestrial inorganic standard value (89). The 14N/ 15N isotopic ratio is found equal to 56-13+16 at 15° S and 56-9+10 at 83° N. Combining the two values yields 14N/ 15N = 56 ± 8, which corresponds to an enrichment in 15N of about 4.9 compared with the terrestrial ratio. These results agree with the values obtained from previous ground-based millimeter observations [Hidayat, T., Marten, A., Bézard, B., Gautier, D., Owen, T., Matthews, H.E., Paubert, G., 1997. Icarus 126, 170-182; Marten, A., Hidayat, T., Biraud, Y., Moreno, R., 2002. Icarus 158, 532-544]. The 15N/ 14N ratio found in HCN is ˜3 times higher than in N 2 [Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779

  9. Inclusion of 13C and D in protonated acetylene

    NASA Astrophysics Data System (ADS)

    Fortenberry, Ryan C.; Roueff, Evelyne; Lee, Timothy J.

    2016-04-01

    The rovibrational spectrum of cyclic, protonated acetylene has been established. The improvement in modern telescopes coupled with the different branching ratios in reaction models welcomes study of 13C-substitution for C2H3+. Quartic force fields (QFFs) have been previously utilized to predict the antisymmetric HCCH stretch in standard c-C2H3+ to within 0.1 cm-1 of experiment and are employed here to generate rovibrational insights for the 13C isotopologues. The zero-point energies are also given for the cyclic and 'Y'-shaped isomers for both 13C and D substitutions. Vibrational intensities and the dipole moments are provided in order to characterize more fully this simple cation.

  10. {sup 13}C relaxation in an RNA hairpin

    SciTech Connect

    King, G.C. |; Akratos, C.; Xi, Z.; Michnica, M.J.

    1994-12-01

    This initial survey of {sup 13}C relaxation in the {triangle}TAR RNA element has generated a number of interesting results that should prove generally useful for future studies. The most readily comparable study in the literature monitored {sup 13}C relaxation of the methyl groups from unusual bases in tRNA{sup Phe}. The study, which used T{sub 1} and NOE data only, reported order parameters for the methyl group axis that ranged between 0.51 and 0.97-a range similar to that observed here. However, they reported a breakdown of the standard order parameter analysis at higher (118-MHz {sup 13}C) frequencies, which should serve to emphasize the need for a thorough exploration of suitable motional models.

  11. Magnetic Resonance Imaging with Hyperpolarized 13C Contrast Agents

    NASA Astrophysics Data System (ADS)

    Gordon, Jeremy W.

    Hyperpolarized 13C substrates offer the potential to non-invasively image metabolism and enzymatic activity. However, hyperpolarization introduces a number of difficulties, and imaging is hampered by non-equilibrium magnetization and the need for spectral encoding. There is therefore a need for fast and RF efficient spectral imaging techniques. This work presents a number of new methods that can be used to improve polarization, increase RF efficiency and improve modeling accuracy in hyperpolarized 13C experiments. In particular, a novel encoding and reconstruction algorithm is presented that can generate spatially and spectrally resolved images with a single RF excitation and echo time. This reconstruction framework increases data acquisition efficiency, enabling accelerated acquisition speed, preserved polarization, and/or improved temporal or spatial resolution. Overall, the methods enumerated in this dissertation have the potential to improve modeling accuracy and to mitigate the conventional tradeoffs between SNR, spatial resolution, and temporal resolution that govern image quality in hyperpolarized 13C experiments.

  12. Interactions between natural-occurring landscape conditions and land use influencing the abundance of riverine smallmouth bass, micropterus dolomieu

    USGS Publications Warehouse

    Brewer, S.K.; Rabeni, C.F.

    2011-01-01

    This study examined how interactions between natural landscape features and land use influenced the abundance of smallmouth bass, Micropterus dolomieu, in Missouri, USA, streams. Stream segments were placed into one of four groups based on natural-occurring watershed characteristics (soil texture and soil permeability) predicted to relate to smallmouth bass abundance. Within each group, stream segments were assigned forest (n = 3), pasture (n = 3), or urban (n = 3) designations based on the percentages of land use within each watershed. Analyses of variance indicated smallmouth bass densities differed between land use and natural conditions. Decision tree models indicated abundance was highest in forested stream segments and lowest in urban stream segments, regardless of group designation. Land use explained the most variation in decision tree models, but in-channel features of temperature, flow, and sediment also contributed significantly. These results are unique and indicate the importance of natural-occurring watershed conditions in defining the potential of populations and how finer-scale filters interact with land use to further alter population potential. Smallmouth bass has differing vulnerabilities to land-use attributes, and the better the natural watershed conditions are for population success, the more resilient these populations will be when land conversion occurs.

  13. Influence of 13C isotopic labeling location of 13C DNP of acetate using TEMPO free radical

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Lumata, Lloyd

    2015-03-01

    Dynamic nuclear polarization (DNP) via the dissolution method enhances the liquid-state magnetic resonance (NMR or MRI) signals of insensitive nuclear spins by at least 10,000-fold. The basis for all these signal enhancements at room temperature is the polarization transfer from the electrons to nuclear spins at cryogenic temperature and high magnetic field. In this work, we have studied the influence of the location of 13C isotopic labeling on the DNP of sodium acetate at 3.35 T and 1.4 K using a wide ESR linewidth free radical 4-oxo-TEMPO. The carbonyl [1-13C]acetate spins produced a polarization level that is almost twice that of the methyl [2-13C]acetate spins. On the other hand, the polarization of the methyl 13C spins doubled to reach the level of [1-13C]acetate when the methyl group was deuterated. Meanwhile, the solid-state nuclear relaxation of these samples are the same and do not correlate with the polarization levels. These behavior implies that the nuclear relaxation for these samples is dominated by the contribution from the free radicals and the polarization levels can be explained by a thermodynamic picture of DNP.

  14. Natural abundance (14)N and (15)N solid-state NMR of pharmaceuticals and their polymorphs.

    PubMed

    Veinberg, Stanislav L; Johnston, Karen E; Jaroszewicz, Michael J; Kispal, Brianna M; Mireault, Christopher R; Kobayashi, Takeshi; Pruski, Marek; Schurko, Robert W

    2016-06-29

    (14)N ultra-wideline (UW), (1)H{(15)N} indirectly-detected HETCOR (idHETCOR) and (15)N dynamic nuclear polarization (DNP) solid-state NMR (SSNMR) experiments, in combination with plane-wave density functional theory (DFT) calculations of (14)N EFG tensors, were utilized to characterize a series of nitrogen-containing active pharmaceutical ingredients (APIs), including HCl salts of scopolamine, alprenolol, isoprenaline, acebutolol, dibucaine, nicardipine, and ranitidine. A case study applying these methods for the differentiation of polymorphs of bupivacaine HCl is also presented. All experiments were conducted upon samples with naturally-abundant nitrogen isotopes. For most of the APIs, it was possible to acquire frequency-stepped UW (14)N SSNMR spectra of stationary samples, which display powder patterns corresponding to pseudo-tetrahedral (i.e., RR'R''NH(+) and RR'NH2(+)) or other (i.e., RNH2 and RNO2) nitrogen environments. Directly-excited (14)N NMR spectra were acquired using the WURST-CPMG pulse sequence, which incorporates WURST (wideband, uniform rate, and smooth truncation) pulses and a CPMG (Carr-Purcell Meiboom-Gill) refocusing protocol. In certain cases, spectra were acquired using (1)H → (14)N broadband cross-polarization, via the BRAIN-CP (broadband adiabatic inversion - cross polarization) pulse sequence. These spectra provide (14)N electric field gradient (EFG) tensor parameters and orientations that are particularly sensitive to variations in local structure and intermolecular hydrogen-bonding interactions. The (1)H{(15)N} idHETCOR spectra, acquired under conditions of fast magic-angle spinning (MAS), used CP transfers to provide (1)H-(15)N chemical shift correlations for all nitrogen environments, except for two sites in acebutolol and nicardipine. One of these two sites (RR'NH2(+) in acebutolol) was successfully detected using the DNP-enhanced (15)N{(1)H} CP/MAS measurement, and one (RNO2 in nicardipine) remained elusive due to the absence of

  15. Rotary resonance recoupling of 13C- 1H dipolar interactions in magic angle spinning 13C NMR of dynamic solids

    NASA Astrophysics Data System (ADS)

    Kitchin, Simon J.; Harris, Kenneth D. M.; Aliev, Abil E.; Apperley, David C.

    2000-06-01

    Rotary resonance recoupling of heteronuclear 13C- 1H dipolar interactions in magic angle spinning solid state 13C NMR spectra (recorded under conditions of 1H decoupling at frequency ν1 and magic angle spinning at frequency νr) has been studied for three examples of molecular solids (adamantane, ferrocene and hexamethylbenzene) in which substantial molecular motion is known to occur. It is shown that when rotary resonance conditions are satisfied (i.e. ν1/νr= n, for n=1 or 2), the recoupling can lead to motionally averaged Pake-like powder patterns from which information on 13C- 1H internuclear distances and/or molecular motion can be derived.

  16. Two-dimensional (13)C-(13)C correlation spectroscopy with magic angle spinning and dynamic nuclear polarization.

    PubMed

    Rosay, Melanie; Weis, Volker; Kreischer, Kenneth E; Temkin, Richard J; Griffin, Robert G

    2002-04-01

    The sensitivity of solid-state NMR experiments can be enhanced with dynamic nuclear polarization (DNP), a technique that transfers the high Boltzmann polarization of unpaired electrons to nuclei. Signal enhancements of up to 23 have been obtained for magic angle spinning (MAS) experiments at 5 T and 85-90 K using a custom-designed high-power gyrotron. The extended stability of MAS/DNP experiments at low temperature is demonstrated with (1)H-driven (13)C spin-diffusion experiments on the amino acid proline. These (13)C-(13)C chemical shift correlation spectra are the first two-dimensional MAS/DNP experiments performed at high field (>1.4 T). PMID:11916398

  17. First airborne samples of a volcanic plume for δ13C of CO2 determinations

    NASA Astrophysics Data System (ADS)

    Fischer, Tobias P.; Lopez, Taryn M.

    2016-04-01

    Volcanic degassing is one of the main natural sources of CO2 to the atmosphere. Carbon isotopes of volcanic gases enable the determination of CO2 sources including mantle, organic or carbonate sediments, and atmosphere. Until recently, this work required sample collection from vents followed by laboratory analyses. Isotope ratio infrared analyzers now enable rapid analyses of plume δ13C-CO2, in situ and in real time. Here we report the first analyses of δ13C-CO2 from airborne samples. These data combined with plume samples from the vent area enable extrapolation to the volcanic source δ13C. We performed our experiment at the previously unsampled and remote Kanaga Volcano in the Western Aleutians. We find a δ13C source composition of -4.4‰, suggesting that CO2 from Kanaga is primarily sourced from the upper mantle with minimal contributions from subducted components. Our method is widely applicable to volcanoes where remote location or activity level precludes sampling using traditional methods.

  18. (1)H-(13)C-(29)Si triple resonance and REDOR solid-state NMR-A tool to study interactions between biosilica and organic molecules in diatom cell walls.

    PubMed

    Wisser, Dorothea; Brückner, Stephan I; Wisser, Florian M; Althoff-Ospelt, Gerhard; Getzschmann, Jürgen; Kaskel, Stefan; Brunner, Eike

    2015-01-01

    Triple resonance solid-state NMR experiments using the spin combination (1)H-(13)C-(29)Si are still rarely found in the literature. This is due to the low natural abundance of the two heteronuclei. Such experiments are, however, increasingly important to study hybrid materials such as biosilica and others. A suitable model substance, ideally labeled with both (13)C and (29)Si, is thus very useful to optimize the experiments before applying them to studies of more complex samples such as biosilica. Tetraphenoxysilane could be synthesized in an easy, two-step synthesis including double isotope labelling. Using tetraphenoxysilane, we established a (1)H-(13)C-(29)Si double CP-based HETCOR experiment and applied it to diatom biosilica from the diatom species Thalassiosira pseudonana. Furthermore, we carried out (1)H-(13)C{(29)Si} CP-REDOR experiments in order to estimate the distance between the organic matrix and the biosilica. Our experiments on diatom biosilica strongly indicate a close contact between polyamine-containing parts of the organic matrix and the silica. This corroborates the assumption that the organic matrix is essential for the control of the cell wall formation. PMID:25638422

  19. Natural abundance 17O DNP two-dimensional and surface-enhanced NMR spectroscopy

    SciTech Connect

    Perras, Frédéric A.; Kobayashi, Takeshi; Pruski, Marek

    2015-06-22

    Due to its extremely low natural abundance and quadrupolar nature, the 17O nuclide is very rarely used for spectroscopic investigation of solids by NMR without isotope enrichment. Additionally, the applicability of dynamic nuclear polarization (DNP), which leads to sensitivity enhancements of 2 orders of magnitude, to 17O is wrought with challenges due to the lack of spin diffusion and low polarization transfer efficiency from 1H. Here, we demonstrate new DNP-based measurements that extend 17O solid-state NMR beyond its current capabilities. The use of the PRESTO technique instead of conventional 1H–17O cross-polarization greatly improves the sensitivity and enables the facile measurement of undistorted line shapes and two-dimensional 1H–17O HETCOR NMR spectra as well as accurate internuclear distance measurements at natural abundance. This was applied for distinguishing hydrogen-bonded and lone 17O sites on the surface of silica gel; the one-dimensional spectrum of which could not be used to extract such detail. As a result, this greatly enhanced sensitivity has enabled, for the first time, the detection of surface hydroxyl sites on mesoporous silica at natural abundance, thereby extending the concept of DNP surface-enhanced NMR spectroscopy to the 17O nuclide.

  20. Is the Multicolored Asian Ladybeetle, Harmonia axyridis, the Most Abundant Natural Enemy to Aphids in Agroecosystems?

    PubMed Central

    Vandereycken, Axel; Durieux, Delphine; Joie, Emilie; Sloggett, John J.; Haubruge, Eric; Verheggen, François J.

    2013-01-01

    The multicolored Asian ladybeetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was introduced into Western Europe in the late 1990s. Since the late 2000s, this species has been commonly considered one of the most abundant aphid predators in most Western European countries. In spite of the large amount of research on H. axyridis, information concerning its relative abundance in agroecosystems is lacking. This study aims to evaluate the abundance of H. axyridis within the aphidophage community in four crops situated in southern Belgium: wheat, Triticum aestivum L. (Poales: Poaceae), corn, Zea mays, potato, Solanum tuberosum (Solanales: Solanaceae), and broad bean Vicia faba (Fabales: Fabaceae). In order to assess the species diversity, the collected data were analyzed by considering (1) the species richness and (2) the evenness according to the Shannon diversity index. Eleven aphidophages were observed in every inventoried agroecosystem, including five abundant species: three coccinellids, the seven-spotted ladybug, Coccinella septempunctata L. (Coleoptera: Coccinellidae), the 14-spotted Ladybird, Propylea quatuordecimpunctata, and H. axyridis; one hoverfly, the marmalade hoverfly, Episyrphus balteatus De Geer (Diptera: Syrphidae); and one lacewing, the common green lacewing, Chrysoperla carnea Stephens sensu lato (= s.l.) (Neuroptera: Chrysopidae). Harmonia axyridis has been observed to thrive, breed, and reproduce on the four studied crops. Harmonia axyridis is the most abundant predator of aphids in corn followed by C. septempunctata, which is the main aphid predator observed in the three other inventoried crops. In wheat and potato fields, H. axyridis occurs in low numbers compared to other aphidophage. These observations suggest that H. axyridis could be considered an invasive species of agrosystems, and that potato and wheat may intermittently act as refuges for other aphidophages vulnerable to intraguild predation by this invader. Harmonia axyridis

  1. Is the multicolored Asian ladybeetle, Harmonia axyridis, the most abundant natural enemy to aphids in agroecosystems?

    PubMed

    Vandereycken, Axel; Durieux, Delphine; Joie, Emilie; Sloggett, John J; Haubruge, Eric; Verheggen, François J

    2013-01-01

    The multicolored Asian ladybeetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), was introduced into Western Europe in the late 1990s. Since the late 2000s, this species has been commonly considered one of the most abundant aphid predators in most Western European countries. In spite of the large amount of research on H. axyridis, information concerning its relative abundance in agroecosystems is lacking. This study aims to evaluate the abundance of H. axyridis within the aphidophage community in four crops situated in southern Belgium: wheat, Triticum aestivum L. (Poales: Poaceae), corn, Zea mays, potato, Solanum tuberosum (Solanales: Solanaceae), and broad bean Vicia faba (Fabales: Fabaceae). In order to assess the species diversity, the collected data were analyzed by considering (1) the species richness and (2) the evenness according to the Shannon diversity index. Eleven aphidophages were observed in every inventoried agroecosystem, including five abundant species: three coccinellids, the seven-spotted ladybug, Coccinella septempunctata L. (Coleoptera: Coccinellidae), the 14-spotted Ladybird, Propylea quatuordecimpunctata, and H. axyridis; one hoverfly, the marmalade hoverfly, Episyrphus balteatus De Geer (Diptera: Syrphidae); and one lacewing, the common green lacewing, Chrysoperla carnea Stephens sensu lato (= s.l.) (Neuroptera: Chrysopidae). Harmonia axyridis has been observed to thrive, breed, and reproduce on the four studied crops. Harmonia axyridis is the most abundant predator of aphids in corn followed by C. septempunctata, which is the main aphid predator observed in the three other inventoried crops. In wheat and potato fields, H. axyridis occurs in low numbers compared to other aphidophage. These observations suggest that H. axyridis could be considered an invasive species of agrosystems, and that potato and wheat may intermittently act as refuges for other aphidophages vulnerable to intraguild predation by this invader. Harmonia axyridis

  2. Spectral editing for in vivo 13C magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Xiang, Yun; Shen, Jun

    2012-01-01

    In vivo detection of carboxylic/amide carbons is a promising technique for studying cerebral metabolism and neurotransmission due to the very low RF power required for proton decoupling. In the carboxylic/amide region, however, there is severe spectral overlap between acetate C1 and glutamate C5, complicating studies that use acetate as an astroglia-specific substrate. There are no known in vivo MRS techniques that can spectrally resolve acetate C1 and glutamate C5 singlets. In this study, we propose to spectrally separate acetate C1 and glutamate C5 by a two-step J-editing technique after introducing homonuclear 13C- 13C scalar coupling between carboxylic/amide carbons and aliphatic carbons. By infusing [1,2- 13C 2]acetate instead of [1- 13C]acetate the acetate doublet can be spectrally edited because of the large separation between acetate C2 and glutamate C4 in the aliphatic region. This technique can be applied to studying acetate transport and metabolism in brain in the carboxylic/amide region without spectral interference.

  3. Synthesis of 2-deoxy-(6-/sup 13/C)glucose

    SciTech Connect

    Walker, T.E.; Unkefer, C.J.; Ehler, D.S.

    1987-05-01

    The authors have prepared 2-deoxy-D-(6-/sup 13/C)glucose which will be used to test the stability of 2-deoxy-D-glucose-6-phosphate in brain tissue. They chose to label 2-deoxy-D-glucose at C-6 because of the large chemical shift difference between C-6 in the free sugar and C-6 in the 6-phosphate analog. Their synthetic scheme is similar to that used for the synthesis of D-(6-/sup 13/C)glucose which involves the removal of C-6 from D-glucose followed by its replacement with /sup 13/C. They first prepare the methyl ..cap alpha..-furanoside using trifluoroacetic acid in methanol. This product is then treated with periodate which cleaves only between C-5 and C-6 to form a hydrated aldehyde which is reacted directly with K/sup 13/CN to form a mixture of nitriles. The enriched nitriles are reduced with hydrogen to a mixture of 6-aldehydo sugars using a 5% Pd on carbon catalyst. These sugars are reduced with NaBH/sub 4/ to a mixture of labeled methyl furanosides. Acid hydrolysis followed by chromatography yields 2-deoxy-D-(6-/sup 13/C)glucose in an overall yield of 10% from K/sup 13/CN.

  4. Increased seawater temperature increases the abundance and alters the structure of natural Vibrio populations associated with the coral Pocillopora damicornis.

    PubMed

    Tout, Jessica; Siboni, Nachshon; Messer, Lauren F; Garren, Melissa; Stocker, Roman; Webster, Nicole S; Ralph, Peter J; Seymour, Justin R

    2015-01-01

    Rising seawater temperature associated with global climate change is a significant threat to coral health and is linked to increasing coral disease and pathogen-related bleaching events. We performed heat stress experiments with the coral Pocillopora damicornis, where temperature was increased to 31°C, consistent with the 2-3°C predicted increase in summer sea surface maxima. 16S rRNA amplicon sequencing revealed a large shift in the composition of the bacterial community at 31°C, with a notable increase in Vibrio, including known coral pathogens. To investigate the dynamics of the naturally occurring Vibrio community, we performed quantitative PCR targeting (i) the whole Vibrio community and (ii) the coral pathogen Vibrio coralliilyticus. At 31°C, Vibrio abundance increased by 2-3 orders of magnitude and V. coralliilyticus abundance increased by four orders of magnitude. Using a Vibrio-specific amplicon sequencing assay, we further demonstrated that the community composition shifted dramatically as a consequence of heat stress, with significant increases in the relative abundance of known coral pathogens. Our findings provide quantitative evidence that the abundance of potential coral pathogens increases within natural communities of coral-associated microbes as a consequence of rising seawater temperature and highlight the potential negative impacts of anthropogenic climate change on coral reef ecosystems. PMID:26042096

  5. Increased seawater temperature increases the abundance and alters the structure of natural Vibrio populations associated with the coral Pocillopora damicornis

    PubMed Central

    Tout, Jessica; Siboni, Nachshon; Messer, Lauren F.; Garren, Melissa; Stocker, Roman; Webster, Nicole S.; Ralph, Peter J.; Seymour, Justin R.

    2015-01-01

    Rising seawater temperature associated with global climate change is a significant threat to coral health and is linked to increasing coral disease and pathogen-related bleaching events. We performed heat stress experiments with the coral Pocillopora damicornis, where temperature was increased to 31°C, consistent with the 2–3°C predicted increase in summer sea surface maxima. 16S rRNA amplicon sequencing revealed a large shift in the composition of the bacterial community at 31°C, with a notable increase in Vibrio, including known coral pathogens. To investigate the dynamics of the naturally occurring Vibrio community, we performed quantitative PCR targeting (i) the whole Vibrio community and (ii) the coral pathogen Vibrio coralliilyticus. At 31°C, Vibrio abundance increased by 2–3 orders of magnitude and V. coralliilyticus abundance increased by four orders of magnitude. Using a Vibrio-specific amplicon sequencing assay, we further demonstrated that the community composition shifted dramatically as a consequence of heat stress, with significant increases in the relative abundance of known coral pathogens. Our findings provide quantitative evidence that the abundance of potential coral pathogens increases within natural communities of coral-associated microbes as a consequence of rising seawater temperature and highlight the potential negative impacts of anthropogenic climate change on coral reef ecosystems. PMID:26042096

  6. Source apportionment of atmospheric PAHs in the Western Balkans by natural abundance radiocarbon analysis

    SciTech Connect

    Zdenek Zencak; Jana Klanova; Ivan Holoubek; Oerjan Gustafsson

    2007-06-01

    Progress in source apportionment of priority combustion-derived atmospheric pollutants can be made by an inverse approach to inventory emissions, namely, receptor-based compound class-specific radiocarbon analysis (CCSRA) of target pollutants. In the present study, CCSRA of the combustion-derived polycyclic aromatic hydrocarbons (PAHs) present in the atmosphere of the countries of the former republic of Yugoslavia was performed. The carbon stable isotope composition ({delta}{sup 13}C) of PAHs varied between -27.68 and -27.19{per_thousand}, whereas {Delta}{sup 14}C values ranged from -568{per_thousand} for PAHs sampled in Kosovo to -288{per_thousand} for PAHs sampled in the Sarajevo area. The application of an isotopic mass balance model to these {Delta}{sup 14}C data revealed a significant contribution (35-65%) from the combustion of non-fossil material to the atmospheric PAH pollution, even in urban and industrialized areas. Furthermore, consistency was observed between the isotopic composition of PAHs obtained by high-volume sampling and those collected by passive sampling. This encourages the use of passive samplers for CCSRA applications. This marks the first time that a CCSRA investigation could be executed on a geographically wide scale, providing a quantitative field-based source apportionment, which points out that also non-fossil combustion processes should be targeted for remedial action. 36 refs., 1 fig., 3 tabs.

  7. NMR study on a novel mucin from jellyfish in natural abundance, Qniumucin from Aurelia aurita.

    PubMed

    Uzawa, Jun; Urai, Makoto; Baba, Takayuki; Seki, Hiroko; Taniguchi, Kayoko; Ushida, Kiminori

    2009-05-22

    A novel mucin (qniumucin), which we recently discovered in jellyfish, was investigated by several NMR techniques. Almost all the peaks in the (13)C and proton NMR spectra were satisfactorily assigned to the amino acids in the main chain and to the bridging GalNAc, the major sugar in the saccharide branches. The amino acid sequence in the tandem repeat part (-VVETTAAP-) was reconfirmed by the cross-peaks between alpha protons and carbonyl carbons in the HMBC spectrum. A connectivity analysis around the O-glycoside bond (GalNAc-Thr) was also performed, and detailed information on the local configuration was obtained by the DPFGSE-NOE-HSD technique. The strategy and the results described in this paper can be extended to the structural analysis of general O-glycan chains, which are more complex than the present mucin. NMR analyses reveal the simple structure of qniumucin extracted by the present protocol, and the homogeneity and purity of qniumucin are probably the result of it being extracted from jellyfish, a primitive animal. PMID:19371080

  8. Optical hyperpolarization of 13C nuclear spins in nanodiamond ensembles

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Schwarz, I.; Jelezko, F.; Retzker, A.; Plenio, M. B.

    2015-11-01

    Dynamical nuclear polarization holds the key for orders of magnitude enhancements of nuclear magnetic resonance signals which, in turn, would enable a wide range of novel applications in biomedical sciences. However, current implementations of DNP require cryogenic temperatures and long times for achieving high polarization. Here we propose and analyze in detail protocols that can achieve rapid hyperpolarization of 13C nuclear spins in randomly oriented ensembles of nanodiamonds at room temperature. Our protocols exploit a combination of optical polarization of electron spins in nitrogen-vacancy centers and the transfer of this polarization to 13C nuclei by means of microwave control to overcome the severe challenges that are posed by the random orientation of the nanodiamonds and their nitrogen-vacancy centers. Specifically, these random orientations result in exceedingly large energy variations of the electron spin levels that render the polarization and coherent control of the nitrogen-vacancy center electron spins as well as the control of their coherent interaction with the surrounding 13C nuclear spins highly inefficient. We address these challenges by a combination of an off-resonant microwave double resonance scheme in conjunction with a realization of the integrated solid effect which, together with adiabatic rotations of external magnetic fields or rotations of nanodiamonds, leads to a protocol that achieves high levels of hyperpolarization of the entire nuclear-spin bath in a randomly oriented ensemble of nanodiamonds even at room temperature. This hyperpolarization together with the long nuclear-spin polarization lifetimes in nanodiamonds and the relatively high density of 13C nuclei has the potential to result in a major signal enhancement in 13C nuclear magnetic resonance imaging and suggests functionalized and hyperpolarized nanodiamonds as a unique probe for molecular imaging both in vitro and in vivo.

  9. Fecal /sup 13/C analysis for the detection and quantitation of intestinal malabsorption

    SciTech Connect

    Schoeller, D.A.; Klein, P.D.; MacLean, W.C. Jr.; Watkins, J.B.; Van Santen, E.

    1981-03-01

    The use of /sup 14/CO/sub 2/ breath tests and fecal analyses for the detection and quantitation of intestinal malabsorption has been extensively documented in adult subjects. The use of stable isotopes has extended the range of breath test applications to include pediatric and obstetric subjects. Here we report a fecal /sup 13/C analysis that can be used in conjunction with /sup 13/CO/sub 2/ breath tests. Twenty-four-hour fecal samples were collected before and after the administration of a labeled substrate. The samples were homogenized and combusted to CO/sub 2/, and the /sup 13/C abundance was determined by high-precision, differential isotope ratio mass spectrometry. The isotopic variation between successive 24 hr fecal samples was 0.6 per thousand (0.0006 atom percent). This variation limited the sensitivity of the fecal analysis to 13 ..mu..mol of /sup 13/C label per mole of fecal carbon. Simultaneous cholyglycine /sup 13/CO/sub 2/ breath tests and fecal assays were performed in five children. One child with bacterial overgrowth had an abnormal breath test and a normal fecal test. Of three children with ileal dysfunction, only one had an abnormal breath test, whereas the fecal test was abnormal in all three. Both the breath test and fecal test were abnormal for a child who had undergone an ileal resection. Both tests were normal for a child with ulcerative colitis.

  10. Assessment of the natural variation of low abundant metabolic proteins in soybean seeds using proteomics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using two-dimensional polyacrylamide gel electrophoresis and mass spectrometry, we investigated the distribution of the low abundant proteins that are involved in soybean seed development in four wild and twelve cultivated soybean genotypes. We found proteomic variation of these proteins within and...

  11. Flow and habitat effects on juvenile fish abundance in natural and altered flow regimes

    USGS Publications Warehouse

    Freeman, Mary C.; Bowen, Z.H.; Bovee, K.D.; Irwin, E.R.

    2001-01-01

    Conserving biological resources native to large river systems increasingly depends on how flow-regulated segments of these rivers are managed. Improving management will require a better understanding of linkages between river biota and temporal variability of flow and instream habitat. However, few studies have quantified responses of native fish populations to multiyear (>2 yr) patterns of hydrologic or habitat variability in flow-regulated systems. To provide these data, we quantified young-of-year (YOY) fish abundance during four years in relation to hydrologic and habitat variability in two segments of the Tallapoosa River in the southeastern United States. One segment had an unregulated flow regime, whereas the other was flow-regulated by a peak-load generating hydropower dam. We sampled fishes annually and explored how continuously recorded flow data and physical habitat simulation models (PHABSIM) for spring (April-June) and summer (July-August) preceding each sample explained fish abundances. Patterns of YOY abundance in relation to habitat availability (median area) and habitat persistence (longest period with habitat area continuously above the long-term median area) differed between unregulated and flow-regulated sites. At the unregulated site, YOY abundances were most frequently correlated with availability of shallow-slow habitat in summer (10 species) and persistence of shallow-slow and shallow-fast habitat in spring (nine species). Additionally, abundances were negatively correlated with 1-h maximum flow in summer (five species). At the flow-regulated site, YOY abundances were more frequently correlated with persistence of shallow-water habitats (four species in spring; six species in summer) than with habitat availability or magnitude of flow extremes. The associations of YOY with habitat persistence at the flow-regulated site corresponded to the effects of flow regulation on habitat patterns. Flow regulation reduced median flows during spring and

  12. Heteronuclear NMR of DNA with the heteronucleus in natural abundance: facilitated assignment and extraction of coupling constants.

    PubMed Central

    Schmieder, P; Ippel, J H; van den Elst, H; van der Marel, G A; van Boom, J H; Altona, C; Kessler, H

    1992-01-01

    Two heteronuclear proton-carbon NMR experiments are applied to the DNA-octamer d(TTGGCCAA)2 with carbon in natural abundance. They lead to a complete assignment of the carbon resonances of the sugars and bases. In addition, several heteronuclear coupling constants, proton-carbon as well as proton-phosphorous and phosphorous-carbon, were determined. The information can be obtained in a reasonable measuring time and offers valuable information for a detailed picture of DNA structure. PMID:1408787

  13. Optical hyperpolarization and inductive readout of 31P donor nuclei in natural abundance single crystal 29Si

    NASA Astrophysics Data System (ADS)

    Alexander, Thomas; Haas, Holger; Deshpande, Rahul; Gumann, Patryk; Cory, David

    2016-05-01

    We optically polarize and inductively detect 31P donor nuclei in single crystal silicon at high magnetic fields (6 . 7T). Samples include both natural abundance 29Si and an isotopically purified 28Si sample. We observe dipolar order in the 29Si nuclear spins through a spin-locking measurement. This provides a means of characterizing spin transport in the vicinity of the 31P donors.

  14. Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

    DOEpatents

    Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

    2009-09-01

    The present invention is directed to labeled compounds, of the formulae ##STR00001## wherein C* is each independently selected from the group consisting of .sup.13C and .sup.12C with the proviso that at least one C* is .sup.13C, each hydrogen of the methylene group can independently be either hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is from the group of sulfide, sulfinyl, and sulfone, Z is an aryl group from the group of 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, and phenyl groups with the structure ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently from the group of hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group from the group of NH.sub.2, NHR and NRR' where R and R' are each independently from the group of a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms.

  15. Synthesis of [1-.sup.13C]pyruvic acid], [2-.sup.13C]pyruvic acid], [3-.sup.13C]pyruvic acid] and combinations thereof

    DOEpatents

    Martinez, Rodolfo A. , Unkefer; Clifford J. , Alvarez; Marc A.

    2012-06-12

    The present invention is directed to the labeled compounds, ##STR00001## wherein C* is each either .sup.13C and .sup.12C where at least one C* is .sup.13C, each hydrogen of the methylene group is hydrogen or deuterium, the methyl group includes either zero or three deuterium atoms, Q is sulfide, sulfinyl, or sulfone, Z is an aryl group such as 1-naphthyl, substituted 1-naphthyl, 2-naphthyl, substituted 2-naphthyl, or a phenyl group ##STR00002## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 are each independently either hydrogen, a C.sub.1-C.sub.4 lower alkyl, a halogen, and an amino group such as NH.sub.2, NHR and NRR' where R and R' are each independently either a C.sub.1-C.sub.4 lower alkyl, a phenyl, and an alkoxy group, and the methyl group can include either zero or three deuterium atoms. The present invention is also directed to the labeled compounds ##STR00003##

  16. Coral 13C/12C records of vertical seafloor displacement during megathrust earthquakes west of Sumatra

    NASA Astrophysics Data System (ADS)

    Gagan, Michael K.; Sosdian, Sindia M.; Scott-Gagan, Heather; Sieh, Kerry; Hantoro, Wahyoe S.; Natawidjaja, Danny H.; Briggs, Richard W.; Suwargadi, Bambang W.; Rifai, Hamdi

    2015-12-01

    The recent surge of megathrust earthquakes and tsunami disasters has highlighted the need for a comprehensive understanding of earthquake cycles along convergent plate boundaries. Space geodesy has been used to document recent crustal deformation patterns with unprecedented precision, however the production of long paleogeodetic records of vertical seafloor motion is still a major challenge. Here we show that carbon isotope ratios (δ13C) in the skeletons of massive Porites corals from west Sumatra record abrupt changes in light exposure resulting from coseismic seafloor displacements. Validation of the method is based on the coral δ13C response to uplift (and subsidence) produced by the March 2005 Mw 8.6 Nias-Simeulue earthquake, and uplift further south around Sipora Island during a M ∼ 8.4 megathrust earthquake in February 1797. At Nias, the average step-change in coral δ13C was 0.6 ± 0.1 ‰ /m for coseismic displacements of +1.8 m and -0.4 m in 2005. At Sipora, a distinct change in Porites microatoll growth morphology marks coseismic uplift of 0.7 m in 1797. In this shallow water setting, with a steep light attenuation gradient, the step-change in microatoll δ13C is 2.3 ‰ /m, nearly four times greater than for the Nias Porites. Considering the natural variability in coral skeletal δ13C, we show that the lower detection limit of the method is around 0.2 m of vertical seafloor motion. Analysis of vertical displacement for well-documented earthquakes suggests this sensitivity equates to shallow events exceeding Mw ∼ 7.2 in central megathrust and back-arc thrust fault settings. Our findings indicate that the coral 13C /12C paleogeodesy technique could be applied to convergent tectonic margins throughout the tropical western Pacific and eastern Indian oceans, which host prolific coral reefs, and some of the world's greatest earthquake catastrophes. While our focus here is the link between coral δ13C, light exposure and coseismic crustal deformation, the

  17. Short-term d13C changes in cultivated soils from Mexico

    NASA Astrophysics Data System (ADS)

    Lounejeva, E.; Etchevers, J.; Morales Puente, P.; Cienfuegos Alvarado, E.; Sedov, S.; Solleiro, E.; Hidalgo, C.

    2007-05-01

    (generally less than -20%o). The common feature for the soils under the Traditional and Traditional improved treatments was a C3 enrichment of the superficial SOM component compared to the underlying layers as a consequence of the dominance of the cultivated C3 species. A similar but more accentuated negative shift is also observed in the SOM from the forest soil (non-cultivated soil d13C -25.2), so the interpretation is uncertain. In the Traditional Organic treatment a clear and perceptible increment of d13C in the SOM carbon signature was observed. This was attributed mainly to the fact that cows manure may contain a lot of C4 coming from feedstuff rich in corn grain that is provided to the animals during grass shortage periods . However, the maize crop introduced in the rotation during the 3rd year had no major effect on the tepetates carbon isotopic signature. The stable isotopic carbon data corresponding to a short period (4 years) of observation in uniformly managed soil ecosystems showed that d13C changed due to the quality of the residues (relative abundance of C3/C4 species) incorporated to the SOC, but this memory is susceptible to undergo changes in the short term and could be rapidly reversed as a consequence of crop management.

  18. Unveiling the Nature of the "Green Pea" Galaxies: Oxygen and Nitrogen Chemical Abundances

    NASA Astrophysics Data System (ADS)

    Amorín, R. O.; Pérez-Montero, E.; Vílchez, J. M.

    2011-07-01

    We present recent results on the oxygen and nitrogen chemical abundances in the extremely compact, low-mass starburst galaxies at redshifts 0.1-0.3 usually referred to as "green pea" galaxies. We show that they are metal-poor galaxies (~1/5 solar) with lower oxygen abundances than star-forming galaxies of similar mass and N/O ratios unusually high for galaxies of the same metallicity. Recent, rapid, and massive inflows of cold gas, possibly coupled with enriched outflows from supernova winds, are used to explain the results. This is consistent with the known "pea" galaxy properties and suggest that these rare objects are experiencing a short and extreme phase in their evolution.

  19. Nature's starships. I. Observed abundances and relative frequencies of amino acids in meteorites

    SciTech Connect

    Cobb, Alyssa K.; Pudritz, Ralph E. E-mail: pudritz@physics.mcmaster.ca

    2014-03-10

    The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation. These meteorites have been classified according to the temperatures and physical conditions of their parent planetesimals. We collate available data on amino acid abundance in these meteorites and plot the concentrations of different amino acids for each meteorite within various meteorite subclasses. We plot average concentrations for various amino acids across meteorites separated by subclass and petrologic type. We see a predominance in the abundance and variety of amino acids in CM2 and CR2 meteorites. The range in temperature corresponding to these subclasses indicates high degrees of aqueous alteration, suggesting aqueous synthesis of amino acids. Within the CM2 and CR2 subclasses, we identify trends in relative frequencies of amino acids to investigate how common amino acids are as a function of their chemical complexity. These two trends (total abundance and relative frequencies) can be used to constrain formation parameters of amino acids within planetesimals. Our organization of the data supports an onion shell model for the temperature structure of planetesimals. The least altered meteorites (type 3) and their amino acids originated near cooler surface regions. The most active amino acid synthesis likely took place at intermediate depths (type 2). The most altered materials (type 1) originated furthest toward parent body cores. This region is likely too hot to either favor amino acid synthesis or for amino acids to be retained after synthesis.

  20. Single voxel localization for dynamic hyperpolarized 13C MR spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Albert P.; Cunningham, Charles H.

    2015-09-01

    The PRESS technique has been widely used to achieve voxel localization for in vivo1H MRS acquisitions. However, for dynamic hyperpolarized 13C MRS experiments, the transition bands of the refocusing pulses may saturate the pre-polarized substrate spins flowing into the voxel. This limitation may be overcome by designing refocusing pulses that do not perturb the resonance of the hyperpolarized substrate, but selectively refocuses the spins of the metabolic products. In this study, a PRESS pulse sequence incorporating spectral-spatial refocusing pulses that have a stop band ('notch') at the substrate resonance is tested in vivo using hyperpolarized [1-13C]pyruvate. Higher metabolite SNR was observed in experiments using the spectral-spatial refocusing pulses as compared to conventional refocusing pulses.

  1. Single voxel localization for dynamic hyperpolarized (13)C MR spectroscopy.

    PubMed

    Chen, Albert P; Cunningham, Charles H

    2015-09-01

    The PRESS technique has been widely used to achieve voxel localization for in vivo(1)H MRS acquisitions. However, for dynamic hyperpolarized (13)C MRS experiments, the transition bands of the refocusing pulses may saturate the pre-polarized substrate spins flowing into the voxel. This limitation may be overcome by designing refocusing pulses that do not perturb the resonance of the hyperpolarized substrate, but selectively refocuses the spins of the metabolic products. In this study, a PRESS pulse sequence incorporating spectral-spatial refocusing pulses that have a stop band ('notch') at the substrate resonance is tested in vivo using hyperpolarized [1-(13)C]pyruvate. Higher metabolite SNR was observed in experiments using the spectral-spatial refocusing pulses as compared to conventional refocusing pulses. PMID:26232365

  2. s-Processing in AGB Stars Revisited. II. Enhanced 13C Production through MHD-induced Mixing

    NASA Astrophysics Data System (ADS)

    Trippella, O.; Busso, M.; Palmerini, S.; Maiorca, E.; Nucci, M. C.

    2016-02-01

    Slow neutron captures are responsible for the production of about 50% of elements heavier than iron, mainly occurring during the asymptotic giant branch phase of low-mass stars (1 ≲ M/M⊙ ≲ 3), where the main neutron source is the 13C(α, n)16O reaction. This last reaction is activated from locally produced 13C, formed by partial mixing of hydrogen into the He-rich layers. We present here the first attempt to describe a physical mechanism for the formation of the 13C reservoir, studying the mass circulation induced by magnetic buoyancy without adding new free parameters to those already involved in stellar modeling. Our approach represents the application to the stellar layers relevant for s-processing of recent exact analytical 2D and 3D models for magneto-hydrodynamic processes at the base of convective envelopes in evolved stars in order to promote downflows of envelope material for mass conservation during the occurrence of a dredge-up phenomenon. We find that the proton penetration is characterized by small concentrations, but is extended over a large fractional mass of the He-layers, thus producing 13C reservoirs of several 10-3 M⊙. The ensuing 13C-enriched zone has an almost flat profile, while only a limited production of 14N occurs. In order to verify the effects of our new findings we show how the abundances of the main s-component nuclei can be accounted for in solar proportions and how our large 13C-reservoir allows us to solve a few so far unexplained features in the abundance distribution of post-AGB objects.

  3. Interlobe communication in 13C-methionine-labeled human transferrin.

    PubMed

    Beatty, E J; Cox, M C; Frenkiel, T A; Tam, B M; Mason, A B; MacGillivray, R T; Sadler, P J; Woodworth, R C

    1996-06-18

    [1H, 13C] NMR investigations of metal-induced conformational changes in the blood serum protein transferrin (80 kDa) are reported. These are thought to play an important role in the recognition of this protein by its cellular receptors. [1H, 13C] NMR resonance assignments are presented for all nine methionine 13CH3 groups of recombinant deglycosylated human transferrin on the basis of studies of recombinant N-lobe (40 kDa, five Met residues), NOESY-relayed [1H, 13C] HMQC spectra, and structural considerations. The first specific assignments for C-lobe resonances of transferrin are presented. Using methionine 13CH3 resonances as probes, it is shown that, with oxalate as the synergistic anion, Ga3+ binds preferentially to the C-lobe and subsequently to the N-lobe. The NMR shifts of Met464, which is in the Trp460-centered hydrophobic patch of helix 5 in the C-lobe in contact with the anion and metal binding site, show that Ga3+ binding causes movement of side chains within this helix, as is also the case in the N-lobe. The C-lobe residue Met382, which contacts the N-lobe hinge region, is perturbed when Ga3+ binds to the N-lobe, indicative of interlobe communication, a feature which may control the recognition of fully-metallated transferrin by its receptor. These results demonstrate that selective 13C labeling is a powerful method for probing the structure and dynamics of high-molecular-mass proteins. PMID:8672464

  4. The Vendian-Cambrian δ 13C record, North Iran: evidence for overturning of the ocean before the Cambrian Explosion

    NASA Astrophysics Data System (ADS)

    Kimura, Hiroto; Matsumoto, Ryo; Kakuwa, Yoshitaka; Hamdi, Bahaeddin; Zibaseresht, Hamid

    Continuous fossilliferous successions across the Precambrian/Cambrian (PC/C) boundary in the Elburz Mountains of Northern Iran show a remarkable negative δ 13C excursion just below the PC/C boundary. High concentrations of manganese, phosphorus, barium, and high abundances of fossil phytoplankton, and black shale coincide with the excursion. Worldwide stratigraphic correlation shows that the isotopic anomaly is a global event. The initial Metazoan diversification, coupled with 13C enrichment, occurs stratigraphically just above the excursion. We propose the following scenario for oceanic environmental changes before the Cambrian Faunal Explosion based on new data from Iran: A global warm climate following the last Precambrian glaciation resulted in a generally stagnant oceanic condition, so that surface water was oxic; deep water was dysoxic, depleted in 13C, and enriched in nutrients. Massive upwelling of deep water (vertical advection of nutrients and 13C-depleted CO 2) caused enhanced phytoplankton productivity and a sharp drop in δ 13C in shallow water carbonate and organic carbon. We conclude that latest Cryptozoic overturning of ocean stratification preceded the Cambrian Explosion.

  5. A strong 13C chemical shift signature provides the coordination mode of histidines in zinc-binding proteins.

    PubMed

    Barraud, Pierre; Schubert, Mario; Allain, Frédéric H-T

    2012-06-01

    Zinc is the second most abundant metal ion incorporated in proteins, and is in many cases a crucial component of protein three-dimensional structures. Zinc ions are frequently coordinated by cysteine and histidine residues. Whereas cysteines bind to zinc via their unique S(γ) atom, histidines can coordinate zinc with two different coordination modes, either N(δ1) or N(ε2) is coordinating the zinc ion. The determination of this coordination mode is crucial for the accurate structure determination of a histidine-containing zinc-binding site by NMR. NMR chemical shifts contain a vast amount of information on local electronic and structural environments and surprisingly their utilization for the determination of the coordination mode of zinc-ligated histidines has been limited so far to (15)N nuclei. In the present report, we observed that the (13)C chemical shifts of aromatic carbons in zinc-ligated histidines represent a reliable signature of their coordination mode. Using a statistical analysis of (13)C chemical shifts, we show that (13)C(δ2) chemical shift is sensitive to the histidine coordination mode and that the chemical shift difference δ{(13)C(ε1)} - δ{(13)C(δ2)} provides a reference-independent marker of this coordination mode. The present approach allows the direct determination of the coordination mode of zinc-ligated histidines even with non-isotopically enriched protein samples and without any prior structural information. PMID:22528293

  6. Natural decay process affects the abundance and community structure of Bacteria and Archaea in Picea abies logs.

    PubMed

    Rinta-Kanto, J M; Sinkko, H; Rajala, T; Al-Soud, W A; Sørensen, S J; Tamminen, M V; Timonen, S

    2016-07-01

    Prokaryotes colonize decaying wood and contribute to the degradation process, but the dynamics of prokaryotic communities during wood decay is still poorly understood. We studied the abundance and community composition of Bacteria and Archaea inhabiting naturally decaying Picea abies logs and tested the hypothesis that the variations in archaeal and bacterial abundances and community composition are coupled with environmental parameters related to the decay process. The data set comprises >500 logs at different decay stages from five geographical locations in south and central Finland. The results show that Bacteria and Archaea are an integral and dynamic component of decaying wood biota. The abundances of bacterial and archaeal 16S rRNA genes increase as wood decay progresses. Changes in bacterial community composition are clearly linked to the loss of density of wood, while specific fungal-bacterial interactions may also affect the distribution of bacterial taxa in decaying wood. Thaumarchaeota were prominent members of the archaeal populations colonizing decaying wood, providing further evidence of the versatility and cosmopolitan nature of this phylum in the environment. The composition and dynamics of the prokaryotic community suggest that they are an active component of biota that are involved in processing substrates in decaying wood material. PMID:27127195

  7. Determination of 15N/14N and 13C/12C in Solid and Aqueous Cyanides

    USGS Publications Warehouse

    Johnson, C.A.

    1996-01-01

    The stable isotopic compositions of nitrogen and carbon in cyanide compounds can be determined by combusting aliquots in sealed tubes to form N2 gas and CO2 gas and analyzing the gases by mass spectrometry. Free cyanide (CN-aq + HCNaq) in simple solutions can also be analyzed by first precipitating the cyanide as copper(II) ferrocyanide and then combusting the precipitate. Reproducibility is ??0.5??? or better for both ??15N and ??13C. If empirical corrections are made on the basis of carbon yields, the reproducibility of ??13C can be improved to ??0.2???. The analytical methods described herein are sufficiently accurate and precise to apply stable isotope techniques to problems of cyanide degradation in natural waters and industrial process solutions.

  8. Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

    PubMed

    Sun, Feng M; Shi, Guang Y; Wang, Hui W

    2016-07-01

    Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs. PMID:27302905

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

    PubMed Central

    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 Δδ15N (δ15N 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

  10. Millimeter and submillimeter wave spectra of 13C methylamine

    NASA Astrophysics Data System (ADS)

    Motiyenko, R. A.; Margulès, L.; Ilyushin, V. V.; Smirnov, I. A.; Alekseev, E. A.; Halfen, D. T.; Ziurys, L. M.

    2016-03-01

    Context. Methylamine (CH3NH2) is a light molecule of astrophysical interest, which has an intensive rotational spectrum that extends in the submillimeter wave range and far beyond, even at temperatures characteristic for the interstellar medium. It is likely for 13C isotopologue of methylamine to be identified in astronomical surveys, but there is no information available for the 13CH3NH2 millimeter and submillimeter wave spectra. Aims: In this context, to provide reliable predictions of 13CH3NH2 spectrum in millimeter and submillimeter wave ranges, we have studied rotational spectra of the 13C methylamine isotopologue in the frequency range from 48 to 945 GHz. Methods: The spectrum of 13C methylamine was recorded using conventional absorption spectrometers. The analysis of the rotational spectrum of 13C methylamine in the ground vibrational state was performed on the basis of the group-theoretical high-barrier tunneling Hamiltonian that was developed for methylamine. The available multiple observations of the parent methylamine species toward Sgr B2(N) at 1, 2, and 3 mm using the Submillimeter Telescope and the 12 m antenna of the Arizona Radio Observatory were used to make a search for interstellar 13CH3NH2. Results: In the recorded spectra, we have assigned 2721 rotational transitions that belong to the ground vibrational state of the 13CH3NH2. These measurements were fitted to the Hamiltonian model that uses 75 parameters to achieve an overall weighted rms deviation of 0.73. On the basis of these spectroscopic results, predictions of transition frequencies in the frequency range up to 950 GHz with J ≤ 50 and Ka ≤ 20 are presented. The search for interstellar 13C methylamine in available observational data was not successful and therefore only an upper limit of 6.5 × 1014 cm-2 can be derived for the column density of 13CH3NH2 toward Sgr B2(N), assuming the same source size, temperature, linewidth, and systemic velocity as for parent methylamine isotopic

  11. Does human activity impact the natural antibiotic resistance background? Abundance of antibiotic resistance genes in 21 Swiss lakes.

    PubMed

    Czekalski, Nadine; Sigdel, Radhika; Birtel, Julia; Matthews, Blake; Bürgmann, Helmut

    2015-08-01

    Antibiotic resistance genes (ARGs) are emerging environmental contaminants, known to be continuously discharged into the aquatic environment via human and animal waste. Freshwater aquatic environments represent potential reservoirs for ARG and potentially allow sewage-derived ARG to persist and spread in the environment. This may create increased opportunities for an eventual contact with, and gene transfer to, human and animal pathogens via the food chain or drinking water. However, assessment of this risk requires a better understanding of the level and variability of the natural resistance background and the extent of the human impact. We have analyzed water samples from 21 Swiss lakes, taken at sampling points that were not under the direct influence of local contamination sources and analyzed the relative abundance of ARG using quantitative real-time PCR. Copy numbers of genes mediating resistance to three different broad-spectrum antibiotic classes (sulfonamides: sul1, sul2, tetracyclines: tet(B), tet(M), tet(W) and fluoroquinolones: qnrA) were normalized to copy numbers of bacterial 16S rRNA genes. We used multiple linear regression to assess if ARG abundance is related to human activities in the catchment, microbial community composition and the eutrophication status of the lakes. Sul genes were detected in all sampled lakes, whereas only four lakes contained quantifiable numbers of tet genes, and qnrA remained below detection in all lakes. Our data indicate higher abundance of sul1 in lakes with increasing number and capacity of wastewater treatment plants (WWTPs) in the catchment. sul2 abundance was rather related to long water residence times and eutrophication status. Our study demonstrates the potential of freshwater lakes to preserve antibiotic resistance genes, and provides a reference for ARG abundance from lake systems with low human impact as a baseline for assessing ARG contamination in lake water. PMID:25913323

  12. Gas Chromatography-Quadrupole Time-of-Flight Mass Spectrometry-Based Determination of Isotopologue and Tandem Mass Isotopomer Fractions of Primary Metabolites for (13)C-Metabolic Flux Analysis.

    PubMed

    Mairinger, Teresa; Steiger, Matthias; Nocon, Justyna; Mattanovich, Diethard; Koellensperger, Gunda; Hann, Stephan

    2015-12-01

    For the first time an analytical work flow based on accurate mass gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOFMS) with chemical ionization for analysis providing a comprehensive picture of (13)C distribution along the primary metabolism is elaborated. The method provides a powerful new toolbox for (13)C-based metabolic flux analysis, which is an emerging strategy in metabolic engineering. In this field, stable isotope tracer experiments based on, for example, (13)C are central for providing characteristic patterns of labeled metabolites, which in turn give insights into the regulation of metabolic pathway kinetics. The new method enables the analysis of isotopologue fractions of 42 free intracellular metabolites within biotechnological samples, while tandem mass isotopomer information is also accessible for a large number of analytes. Hence, the method outperforms previous approaches in terms of metabolite coverage, while also providing rich isotopomer information for a significant number of key metabolites. Moreover, the established work flow includes novel evaluation routines correcting for isotope interference of naturally distributed elements, which is crucial following derivatization of metabolites. Method validation in terms of trueness, precision, and limits of detection was performed, showing excellent analytical figures of merit with an overall maximum bias of 5.8%, very high precision for isotopologue and tandem mass isotopomer fractions representing >10% of total abundance, and absolute limits of detection in the femtomole range. The suitability of the developed method is demonstrated on a flux experiment of Pichia pastoris employing two different tracers, i.e., 1,6(13)C2-glucose and uniformly labeled (13)C-glucose. PMID:26513365

  13. /sup 13/C-/sup 13/C spin-spin coupling constants in structural investigations. II. Conformational structure of vinyl ethers

    SciTech Connect

    Krivdin, L.B.; Shcherbakov, V.V.; Bzhezovskii, V.M.; Kalabin, G.A.

    1986-10-10

    The /sup 13/C-/sup 13/C spin-spin coupling constants between the carbon nuclei of the vinyl group were measured for a series of vinyl ethers. It was established that the unshared electron pairs of the oxygen atom can make a substantial stereospecific contribution to the direct /sup 13/C-/sup 13/C constants of the adjacent nuclei. The observed effect was used to establish the conformational structure of the compounds.

  14. ASSESSING ABUNDANCE DISTRIBUTIONS IN NATURAL COMMUNITIES OF ECTOMYCORRHIZAS ALONG AN ENVIRONMENTAL GRADIENT

    EPA Science Inventory

    Alpha diversity indices often fail to distinguish between natural populations that a more detailed investigation of the distribution of ramets among types would show are quite different. We studied the effectiveness of applying SHE analyses to morphotype classifications of ectom...

  15. Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids

    PubMed Central

    You, Le; Page, Lawrence; Feng, Xueyang; Berla, Bert; Pakrasi, Himadri B.; Tang, Yinjie J.

    2012-01-01

    Microbes have complex metabolic pathways that can be investigated using biochemistry and functional genomics methods. One important technique to examine cell central metabolism and discover new enzymes is 13C-assisted metabolism analysis 1. This technique is based on isotopic labeling, whereby microbes are fed with a 13C labeled substrates. By tracing the atom transition paths between metabolites in the biochemical network, we can determine functional pathways and discover new enzymes. As a complementary method to transcriptomics and proteomics, approaches for isotopomer-assisted analysis of metabolic pathways contain three major steps 2. First, we grow cells with 13C labeled substrates. In this step, the composition of the medium and the selection of labeled substrates are two key factors. To avoid measurement noises from non-labeled carbon in nutrient supplements, a minimal medium with a sole carbon source is required. Further, the choice of a labeled substrate is based on how effectively it will elucidate the pathway being analyzed. Because novel enzymes often involve different reaction stereochemistry or intermediate products, in general, singly labeled carbon substrates are more informative for detection of novel pathways than uniformly labeled ones for detection of novel pathways3, 4. Second, we analyze amino acid labeling patterns using GC-MS. Amino acids are abundant in protein and thus can be obtained from biomass hydrolysis. Amino acids can be derivatized by N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (TBDMS) before GC separation. TBDMS derivatized amino acids can be fragmented by MS and result in different arrays of fragments. Based on the mass to charge (m/z) ratio of fragmented and unfragmented amino acids, we can deduce the possible labeled patterns of the central metabolites that are precursors of the amino acids. Third, we trace 13C carbon transitions in the proposed pathways and, based on the isotopomer data, confirm whether these

  16. THz spectroscopy and first ISM detection of excited torsional states of 13C-methyl formate

    NASA Astrophysics Data System (ADS)

    Haykal, I.; Carvajal, M.; Tercero, B.; Kleiner, I.; López, A.; Cernicharo, J.; Motiyenko, R. A.; Huet, T. R.; Guillemin, J. C.; Margulès, L.

    2014-08-01

    Context. An astronomical survey of interstellar molecular clouds needs a previous analysis of the spectra in the microwave and sub-mm energy range of organic molecules to be able to identify them. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of rotational spectra. These constants can be used to predict the transitions frequencies very precisely that were not measured in the laboratory. Aims: We present the experimental study and its theoretical analysis for two 13C-methyl formate isotopologues to detect these two isotopologues for the first time in their excited torsional states, which lie at 130 cm-1 (200 K) in Orion-KL. Methods: New spectra of HCOO13CH3 (13C2) methyl formate were recorded with the mm- and submm-wave spectrometer in Lille from 50 to 940 GHz. A global fit for vt = 0 and 1 was accomplished with the BELGI program to reproduce the experimental spectra with greater accuracy. Results: We analysed 5728 and 2881 new lines for vt = 0 and 1 for HCOO13CH3. These new lines were globally fitted with 846 previously published lines for vt = 0. In consequence, 52 parameters of the RAM Hamiltonian were accurately determined and the value of the barrier height (V3 = 369.93168(395) cm-1) was improved. We report the detection of the first excited torsional states (vt = 1) in Orion-KL for the 13C2 and 13C1 methyl formate based on the present analysis and previously published data. We provide column densities, isotopic abundances, and vibrational temperatures for these species. Conclusions: Following this work, accurate prediction can be provided. This permits detecting 135 features of the first excited torsional states of 13C-methyl formate isotopologues in Orion-KL in the 80-280 GHz frequency range, without missing lines. Full Table A.1 and the IRAM spectra as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/568

  17. [Bioremediation of oil-polluted soils: using the [13C]/[12C] ratio to characterize microbial products of oil hydrocarbon biodegradation].

    PubMed

    Ziakun, A M; Brodskiĭ, E S; Baskunov, B P; Zakharchenko, V N; Peshenko, V P; Filonov, A E; Vetrova, A A; Ivanova, A A; Boronin, A M

    2014-01-01

    We compared data on the extent of bioremediation in soils polluted with oil. The data were obtained using conventional methods of hydrocarbon determination: extraction gas chromatography-mass spectrometry, extraction IR spectroscopy, and extraction gravimetry. Due to differences in the relative abundances of the stable carbon isotopes (13C/12C) in oil and in soil organic matter, these ratios could be used as natural isotopic labels of either substance. Extraction gravimetry in combination with characteristics of the carbon isotope composition of organic products in the soil before and after bioremediation was shown to be the most informative approach to an evaluation of soil bioremediation. At present, it is the only method enabling quantification of the total petroleum hydrocarbons in oil-polluted soil, as well as of the amounts of hydrocarbons remaining after bioremediation and those microbially transformed into organic products and biomass. PMID:25707107

  18. Nitrate dynamics in natural plants: insights based on the concentration and natural isotope abundances of tissue nitrate

    PubMed Central

    Liu, Xue-Yan; Koba, Keisuke; Makabe, Akiko; Liu, Cong-Qiang

    2014-01-01

    The dynamics of nitrate (NO−3), a major nitrogen (N) source for natural plants, has been studied mostly through experimental N addition, enzymatic assay, isotope labeling, and genetic expression. However, artificial N supply may not reasonably reflect the N strategies in natural plants because NO−3 uptake and reduction may vary with external N availability. Due to abrupt application and short operation time, field N addition, and isotopic labeling hinder the elucidation of in situ NO−3-use mechanisms. The concentration and natural isotopes of tissue NO−3 can offer insights into the plant NO−3 sources and dynamics in a natural context. Furthermore, they facilitate the exploration of plant NO−3 utilization and its interaction with N pollution and ecosystem N cycles without disturbing the N pools. The present study was conducted to review the application of the denitrifier method for concentration and isotope analyses of NO−3 in plants. Moreover, this study highlights the utility and advantages of these parameters in interpreting NO−3 sources and dynamics in natural plants. We summarize the major sources and reduction processes of NO−3 in plants, and discuss the implications of NO−3 concentration in plant tissues based on existing data. Particular emphasis was laid on the regulation of soil NO−3 and plant ecophysiological functions in interspecific and intra-plant NO−3 variations. We introduce N and O isotope systematics of NO−3 in plants and discuss the principles and feasibilities of using isotopic enrichment and fractionation factors; the correlation between concentration and isotopes (N and O isotopes: δ18O and Δ17O); and isotope mass-balance calculations to constrain sources and reduction of NO−3 in possible scenarios for natural plants are deliberated. Finally, we offer a preliminary framework of intraplant δ18O-NO−3 variation, and summarize the uncertainties in using tissue NO−3 parameters to interpret plant NO−3 utilization

  19. Natural expansion and experimental manipulation of seagrass ( Zostera spp.) abundance and the response of infaunal invertebrates

    NASA Astrophysics Data System (ADS)

    Harrison, Paul G.

    1987-06-01

    A study of an expanding seagrass bed on the south-west coast of British Columbia, Canada involved documentation and explanation of the pattern of expansion of the vegetation as well as documentation and experimental investigation of the accompanying changes in the distribution of infaunal invertebrates. Expansion followed a major environmental change, improved water clarity initiated in 1969 when a causeway blocked access to the site for silty Fraser River water. The original eelgrass ( Zostera marina) bed expanded landward over 30 m year -1, probably causing more and more water to be retained in the bed at low tide and thus improving its own habitat. More rapid expansion occurred from 1979-1983 after Z.japonica colonized at the landward edge of the eelgrass bed and in a separate intertidal area. Expansion ceased around 1983 coincident with, but probably independent of, further construction. Burrowing shrimp ( Callianassa californiensis) decreased in abundance between 1977 and 1984 in areas where the two seagrasses colonized. Short-term experiment over one summer and fall showed that removal of all shoots allowed adult shrimp and tube worms to colonize the sediment while addition of shoots of Z. japonica by transplanting caused temporary decreases in shrimp abundance. After a few weeks an established shrimp population destroyed the transplants. Among reasonable alternate hypotheses for the decline in Callianassa, the effect of sediment texture can be eliminated, but either direct negative effects of seagrass, i.e. inhibition of the burrowing of adult shrimp or of settlement of juveniles, or indirect effects, i.e. the harboring of more predators of shrimp in seagrass beds, deserve further study.

  20. Mechanisms linking metabolism of Helicobacter pylori to 18O and 13C-isotopes of human breath CO2

    PubMed Central

    Som, Suman; De, Anulekha; Banik, Gourab Dutta; Maity, Abhijit; Ghosh, Chiranjit; Pal, Mithun; Daschakraborty, Sunil B.; Chaudhuri, Sujit; Jana, Subhra; Pradhan, Manik

    2015-01-01

    The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 (18O) and carbon-13 (13C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of 18O/16O and 13C/12C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of 18O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of 18O in breath CO2 were manifested in individuals without the infections. In contrast, the 13C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to 13C-enriched glucose uptake, whereas a distinguishable change of breath 13C/12C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose. Moreover, monitoring the 18O and 13C-isotopic exchange in breath CO2 successfully diagnosed the eradications of Helicobacter pylori infections following a standard therapy. Our findings suggest that breath 12C18O16O and 13C16O16O can be used as potential molecular biomarkers to distinctively track the pathogenesis of Helicobacter pylori and also for eradication purposes and thus may open new perspectives into the pathogen’s physiology along with isotope-specific non-invasive diagnosis of the infection. PMID:26039789

  1. Enhancing Phospholipid Fatty Acid Profiling of Soil Bacterial Communities via Substrate- Specific 13C-labelling

    NASA Astrophysics Data System (ADS)

    Evershed, R. P.; Maxfield, P. J.; Bingham, E. M.; Dildar, N.; Brennand, E. L.; Hornibrook, E.

    2008-12-01

    A range of culture-independent methods, has recently emerged to study environmental microorganisms in situ[1]. One such method is phospholipid fatty acid (PLFA) analysis, wherein these ubiquitous membrane lipids provide a powerful tool for the study of unculturable soil microorganisms. PLFA analyses have been used to investigate the impacts of a wide range of environmental factors on the soil microbial community. An acknowledged shortcoming of the PLFAs approach is the lack the chemotaxonoic specificity, which restricts the ability of the method to probe the activities of specific functional groups of the microbial community selectively. However, the selectivity of PLFAs analyses can be enhanced by incubating soils with 13C- labelled substrates followed by gas chromatography-combustion-isotope ratio mass spectrometry to reveal the specific PLFAs incorporating the 13C-label. The application of this approach will be demonstrated through our recent work on methanotrophic bacteria in soils. We applied this approach initially to mineral soils[2] and then extended chemotaxonomic assessments by using a combination of 13C-labelled PLFAs and hopanoids [3]. We have used this approach to explore the properties of high affinity methanotrophs in a range of environments, investigating the relationship between methane oxidation rates and the nature and magnitude of the methanotrophic community for the first time[4,5] More recently we extended the technique using a novel time series 13C-labelling of PLFAs[6] to estimate the rate and progression of 13C- label incorporation and turnover of methanotrophic populations. This modified approach has been used to investigate the impacts of various environmental variables, e.g. soil type, vegetation cover and land use, on the methanotrophic biomass[7.8]. The unique nature of the 13CH4 as a gaseous substate/carbon source means that can be readily introduced into soils via a specific subset of the soil microbial biomass, thereby offering many

  2. Galactose oxidation using (13)C in healthy and galactosemic children.

    PubMed

    Resende-Campanholi, D R; Porta, G; Ferrioli, E; Pfrimer, K; Ciampo, L A Del; Junior, J S Camelo

    2015-03-01

    Galactosemia is an inborn error of galactose metabolism that occurs mainly as the outcome of galactose-1-phosphate uridyltransferase (GALT) deficiency. The ability to assess galactose oxidation following administration of a galactose-labeled isotope (1-(13)C-galactose) allows the determination of galactose metabolism in a practical manner. We aimed to assess the level of galactose oxidation in both healthy and galactosemic Brazilian children. Twenty-one healthy children and seven children with galactosemia ranging from 1 to 7 years of age were studied. A breath test was used to quantitate (13)CO2 enrichment in exhaled air before and at 30, 60, and 120 min after the oral administration of 7 mg/kg of an aqueous solution of 1-(13)C-galactose to all children. The molar ratios of (13)CO2 and (12)CO2 were quantified by the mass/charge ratio (m/z) of stable isotopes in each air sample by gas-isotope-ratio mass spectrometry. In sick children, the cumulative percentage of (13)C from labeled galactose (CUMPCD) in the exhaled air ranged from 0.03% at 30 min to 1.67% at 120 min. In contrast, healthy subjects showed a much broader range in CUMPCD, with values from 0.4% at 30 min to 5.58% at 120 min. The study found a significant difference in galactose oxidation between children with and without galactosemia, demonstrating that the breath test is useful in discriminating children with GALT deficiencies. PMID:25608239

  3. 13C/31P NMR studies on the role of glucose transport/phosphorylation in human glycogen supercompensation.

    PubMed

    Price, T B; Laurent, D; Petersen, K F

    2003-05-01

    This study measured muscle glycogen during a 7-day carbohydrate loading protocol. Twenty healthy subjects (12 male, 8 female) performed 1 hr treadmill/toe-raise exercise immediately before a 3-day low carbohydrate (LoCHO) diet (20 % carbohydrate, 60 % fat, 20 % protein). On day 3 they repeated the exercise and began a 4-day high carbohydrate (HiCHO) diet (90 % carbohydrate, 2 % fat, 8 % protein). The order of administration of the diet was reversed in a subpopulation (n = 3). Interleaved natural abundance 13C/ 31P NMR spectra were obtained before and immediately after exercise, and each day during the controlled diets in order to determine concentrations of glycogen (GLY), glucose-6-phosphate (G6P), and muscle pH. Following exercise, muscle GLY and pH were reduced (p < 0.001) while muscle G6P was elevated (p

  4. Isotopic finger-printing of active pharmaceutical ingredients by 13C NMR and polarization transfer techniques as a tool to fight against counterfeiting.

    PubMed

    Bussy, Ugo; Thibaudeau, Christophe; Thomas, Freddy; Desmurs, Jean-Roger; Jamin, Eric; Remaud, Gérald S; Silvestre, Virginie; Akoka, Serge

    2011-09-30

    The robustness of adiabatic polarization transfer methods has been evaluated for determining the carbon isotopic finger-printing of active pharmaceutical ingredients. The short time stabilities of the adiabatic DEPT and INEPT sequences are very close to that observed with the one pulse sequence, but the DEPT long time stability is not sufficient for isotopic measurements at natural abundance or low enrichment. Using the INEPT sequence for (13)C isotopic measurements induces a dramatic reduction in the experimental time without deterioration in short time or long time stability. It appears, therefore, to be a method of choice for obtaining the isotopic finger-print of different ibuprofen samples in a minimum time. The results obtained on 13 commercial ibuprofen samples from different origins show that this strategy can be used effectively to determine (13)C distribution within a given molecule and to compare accurately differences in the isotopic distribution between different samples of the given molecule. The present methodology is proposed as a suitable tool to fight against counterfeiting. PMID:21872037

  5. Sensitive, Efficient Quantitation of 13C-Enriched Nucleic Acids via Ultrahigh-Performance Liquid Chromatography–Tandem Mass Spectrometry for Applications in Stable Isotope Probing

    PubMed Central

    Wilhelm, Roland; Szeitz, András; Klassen, Tara L.

    2014-01-01

    Stable isotope probing (SIP) of nucleic acids is a powerful tool for studying the functional traits of microbial populations within complex communities, but SIP involves a number of technical challenges. Many of the difficulties in DNA-SIP and RNA-SIP experiments can be effectively overcome with an efficient, sensitive method for quantitating the isotopic enrichment of nucleic acids. Here, we present a sensitive method for quantitating 13C enrichment of nucleic acids, requiring a few nanograms of sample, and we demonstrate its utility in typical DNA-SIP and RNA-SIP experiments. All five nucleobases (adenine, guanine, cytosine, thymine, and uracil) were separated and detected by using ultrahigh-performance liquid chromatography–tandem mass spectrometry. We detected all isotopic species in samples with as low as 1.5 atom% 13C above natural abundance, using 1-ng loadings. Quantitation was used to characterize the isotopic enrichment kinetics of cellulose- and lignin-based microcosm experiments and to optimize the recovery of enriched nucleic acids. Application of our method will minimize the quantity of expensive isotopically labeled substrates required and reduce the risk of failed experiments due to insufficient recovery of labeled nucleic acids for sequencing library preparation. PMID:25217022

  6. The 13C nuclear magnetic resonance in graphite intercalation compounds

    NASA Technical Reports Server (NTRS)

    Tsang, T.; Resing, H. A.

    1985-01-01

    The (13)C NMR chemical shifts of graphite intercalation compounds were calculated. For acceptor types, the shifts come mainly from the paramagnetic (Ramsey) intra-atomic terms. They are related to the gross features of the two-dimensional band structures. The calculated anisotropy is about -140 ppm and is independent of the finer details such as charge transfer. For donor types, the carbon 2p pi orbitals are spin-polarized because of mixing with metal conduction electrons, thus there is an additional dipolar contribution which may be correlated with the electronic specific heat. The general agreement with experimental data is satisfactory.

  7. S-Factor of radiative р 13C capture

    NASA Astrophysics Data System (ADS)

    Dubovichenko, S. B.

    2012-06-01

    The possibility of description of experimental data on the astrophysical S-factor of radiative р 13C capture within the framework of the potential cluster model with forbidden states is analyzed at energies in the range 0.03-0.8 MeV. It is demonstrated that the behavior of the astrophysical S-factor can be explained based on the Е1-transition to the bound 3 P 1 state of the 14N nucleus in the р 13С channel from the 3 S 1 wave of р 13С scattering at resonant energy of 0.55 MeV (l.s.).

  8. Absolute partial decay-branch measurements in 13C

    NASA Astrophysics Data System (ADS)

    Wheldon, C.; Ashwood, N. I.; Barr, M.; Curtis, N.; Freer, M.; Kokalova, Tz.; Malcolm, J. D.; Ziman, V. A.; Faestermann, Th.; Wirth, H.-F.; Hertenberger, R.; Lutter, R.

    2012-10-01

    The 9Be(6Li,d)13C* reaction at a beam energy of 42 MeV has been investigated using a large-acceptance silicon-strip detector array and the high-resolution Q3D magnetic spectrograph. The Q3D facilitated the unambiguous determination of the reaction channel via identification of the deuteron ejectile, thereby providing the spectrum of excited states in 13C in the range from 10.7 to 15.0 MeV. The silicon array was used to detect and identify the 13C recoil-breakup products with efficiencies of up to 49%. The results obtained for the absolute partial branching ratios represent the first complete measurements for states in this energy region and allow the extraction of reduced widths. The quantities measured for Γn0/Γtot and Γn1/Γtot are 0.91±0.11 and ≤0.13 (10.753 MeV), 0.51±0.04 and 0.51±0.04 (10.818 MeV), 0.68±0.03 and 0.42±0.02 (10.996 MeV), 0.49±0.08 and 0.71±0.11 (11.848 MeV), and 0.49±0.08 and 0.53±0.08 (12.130 MeV), respectively. For the two observed higher-lying energy levels, Γα0/Γtot and Γn1/Γtot have been measured as 0.54±0.02 and 0.45±0.02 (13.760 MeV) and 0.94±0.03 and 0.13±0.02 (14.582 MeV), respectively. The consequences for the proposed molecular structures in 13C are explored following the extraction of reduced widths.

  9. A Catalyzing Phantom for Reproducible Dynamic Conversion of Hyperpolarized [1-13C]-Pyruvate

    PubMed Central

    Walker, Christopher M.; Lee, Jaehyuk; Ramirez, Marc S.; Schellingerhout, Dawid; Millward, Steven; Bankson, James A.

    2013-01-01

    In vivo real time spectroscopic imaging of hyperpolarized 13C labeled metabolites shows substantial promise for the assessment of physiological processes that were previously inaccessible. However, reliable and reproducible methods of measurement are necessary to maximize the effectiveness of imaging biomarkers that may one day guide personalized care for diseases such as cancer. Animal models of human disease serve as poor reference standards due to the complexity, heterogeneity, and transient nature of advancing disease. In this study, we describe the reproducible conversion of hyperpolarized [1-13C]-pyruvate to [1-13C]-lactate using a novel synthetic enzyme phantom system. The rate of reaction can be controlled and tuned to mimic normal or pathologic conditions of varying degree. Variations observed in the use of this phantom compare favorably against within-group variations observed in recent animal studies. This novel phantom system provides crucial capabilities as a reference standard for the optimization, comparison, and certification of quantitative imaging strategies for hyperpolarized tracers. PMID:23977006

  10. Late Ordovician land plant spore 13C fractionation records atmospheric CO2 and climate change

    NASA Astrophysics Data System (ADS)

    Beerling, D. J.; Nelson, D. M.; Pearson, A.; Wellman, C.

    2008-12-01

    Molecular systematics and spore wall ultrastructure studies indicate that late Ordovician diad and triad fossil spores were likely produced by plants most closely related to liverworts. Here, we report the first δ13C estimates of Ordovician fossil land plant spores, which were obtained using a spooling wire micro-combustion device interfaced with an isotope-ratio mass spectrometer (Sessions et al., 2005, Analytical Chemistry, 77, 6519). The spores all originate from Saudi Arabia on the west of Gondwana and date to before (Cardadoc, ca. 460 Ma), during (443Ma) and after (Llandovery, ca. 440Ma) the Hirnantian glaciation. We use these numbers along with marine carbonate δ13C records to estimate atmospheric CO2 by implementing a theoretical model that captures the strong CO2-dependency of 13C fractionation in non-vascular land plants (Fletcher et al., 2008, Nature Geoscience, 1, 43). Although provisional at this stage, reconstructed CO2 changes are consistent with the Kump et al. (2008) (Paleo. Paleo. Paleo. 152, 173) 'weathering hypothesis' whereby pre-Hirnantian cooling is caused by relatively low CO2 (ca. 700ppm) related to enhanced weathering of young basaltic rocks during the early phase of the Taconic uplift, with background values subsequently rising to around double this value by the earliest Silurian. Further analyses will better constrain atmospheric CO2 change during the late Ordovician climatic perturbation and address controversial hypotheses concerning the causes and timing of the Earth system transition into an icehouse state.

  11. Temperature-mediated changes in microbial carbon use efficiency and 13C discrimination

    NASA Astrophysics Data System (ADS)

    Lehmeier, Christoph A.; Ballantyne, Ford, IV; Min, Kyungjin; Billings, Sharon A.

    2016-06-01

    Understanding how carbon dioxide (CO2) flux from ecosystems feeds back to climate warming depends in part on our ability to quantify the efficiency with which microorganisms convert organic carbon (C) into either biomass or CO2. Quantifying ecosystem-level respiratory CO2 losses often also requires assumptions about stable C isotope fractionations associated with the microbial transformation of organic substrates. However, the diversity of organic substrates' δ13C and the challenges of measuring microbial C use efficiency (CUE) in their natural environment fundamentally limit our ability to project ecosystem C budgets in a warming climate. Here, we quantify the effect of temperature on C fluxes during metabolic transformations of cellobiose, a common microbial substrate, by a cosmopolitan microorganism growing at a constant rate. Biomass C specific respiration rate increased by 250 % between 13 and 26.5 °C, decreasing CUE from 77 to 56 %. Biomass C specific respiration rate was positively correlated with an increase in respiratory 13C discrimination from 4.4 to 6.7 ‰ across the same temperature range. This first demonstration of a direct link between temperature, microbial CUE, and associated isotope fluxes provides a critical step towards understanding δ13C of respired CO2 at multiple scales, and towards a framework for predicting future ecosystem C fluxes.

  12. Design of a sup 13 C (1H) RF probe for monitoring the in vivo metabolism of (1- sup 13 C)glucose in primate brain

    SciTech Connect

    Hammer, B.E.; Sacks, W.; Bigler, R.E.; Hennessy, M.J.; Sacks, S.; Fleischer, A.; Zanzonico, P.B. )

    1990-01-01

    The design of an RF probe suitable for obtaining proton-decoupled {sup 13}C spectra from a subhuman primate brain is described. Two orthogonal saddle coils, one tuned to the resonant frequency of {sup 13}C and the other to the resonant frequency of 1H, were used to monitor the in vivo metabolism of (1-{sup 13}C)glucose in rhesus monkey brain at 2.1 T. Difference spectra showed the appearance of {sup 13}C-enriched glutamate and glutamine 30 to 40 min after a bolus injection of (1-{sup 13}C)glucose.

  13. Using Neural Networks for 13C NMR Chemical Shift Prediction-Comparison with Traditional Methods

    NASA Astrophysics Data System (ADS)

    Meiler, Jens; Maier, Walter; Will, Martin; Meusinger, Reinhard

    2002-08-01

    Interpretation of 13C chemical shifts is essential for structure elucidation of organic molecules by NMR. In this article, we present an improved neural network approach and compare its performance to that of commonly used approaches. Specifically, our recently proposed neural network ( J. Chem. Inf. Comput. Sci. 2000, 40, 1169-1176) is improved by introducing an extended hybrid numerical description of the carbon atom environment, resulting in a standard deviation (std. dev.) of 2.4 ppm for an independent test data set of ˜42,500 carbons. Thus, this neural network allows fast and accurate 13C NMR chemical shift prediction without the necessity of access to molecule or fragment databases. For an unbiased test dataset containing 100 organic structures the accuracy of the improved neural network was compared to that of a prediction method based on the HOSE code ( hierarchically ordered spherical description of environment) using S PECI NFO. The results show the neural network predictions to be of quality (std. dev.=2.7 ppm) comparable to that of the HOSE code prediction (std. dev.=2.6 ppm). Further we compare the neural network predictions to those of a wide variety of other 13C chemical shift prediction tools including incremental methods (C HEMD RAW, S PECT OOL), quantum chemical calculation (G AUSSIAN, C OSMOS), and HOSE code fragment-based prediction (S PECI NFO, ACD/CNMR, P REDICTI T NMR) for the 47 13C-NMR shifts of Taxol, a natural product including many structural features of organic substances. The smallest standard deviations were achieved here with the neural network (1.3 ppm) and S PECI NFO (1.0 ppm).

  14. Deconvolution of the tree ring based delta/sup 13/C record

    SciTech Connect

    Peng, T.; Broecker, W.S.; Freyer, H.D.; Trumbore, S.

    1983-04-20

    We assumed that the tree-ring based /sup 13/C//sup 12/C record constructed by Freyer and Belacy (1983) to be representative of the fossil fuel and forest-soil induced /sup 13/C//sup 12/C change for atmospheric CO/sub 2/. Through the use of a modification of the Oeschger et al. ocean model, we have computed the contribution of the combustion of coal, oil, and natural gas to this observed /sup 13/C//sup 12/C change. A large residual remains when the tree-ring-based record is corrected for the contribution of fossil fuel CO/sub 2/. A deconvolution was performed on this residual to determine the time history and magnitude of the forest-soil reservoir changes over the past 150 years. Several important conclusions were reached. (1) The magnitude of the integrated CO/sub 2/ input from these sources was about 1.6 times that from fossil fuels. (2) The forest-soil contribution reached a broad maximum centered at about 1900. (3) Over the 2 decade period covered by the Mauna Loa atmospheric CO/sub 2/ content record, the input from forests and soils was about 30% that from fossil fuels. (4) The /sup 13/C//sup 12/C trend over the last 20 years was dominated by the input of fossil fuel CO/sub 2/. (5) The forest-soil release did not contribute significantly to the secular increase in atmospheric CO/sub 2/ observed over the last 20 years. (6) The pre-1850 atmospheric p2 values must have been in the range 245 to 270 x 10/sup -6/ atmospheres.

  15. Declining moisture availability in late Eocene Antarctica as deduced from Nothofagus sporopollenin δ13C

    NASA Astrophysics Data System (ADS)

    Griener, K. W.; Nelson, D. M.; Warny, S.

    2012-12-01

    Palynological data demonstrate that significant changes in vegetation and climate occurred at the Eocene-Oligocene (E-O) Boundary on the Antarctic Peninsula. These changes include decreases in terrestrial palynomorph abundance and diversity as well as dinoflagellate assemblages that reflect colder sea surface temperatures and increased glaciation (Warny and Askin, 2011). Understanding the factors controlling these changes in climate and vegetation is a topic of great interest. One area of remaining uncertainty is how the hydrologic regime varied during Antarctica's shift from greenhouse to icehouse conditions. For example, estimates of Antarctic precipitation from around the E-O boundary based on plant leaf margins (e.g. Francis et al., 2008), clay mineralogy (e.g. Christian and Kennett, 1997), and models (Thorn and DeConto 2006) are vastly different. We used a moving-wire device interfaced with an isotope-ratio mass spectrometer (Sessions et al., 2005; Nelson et al., 2008) to analyze δ13C of small quantities of Nothofagus sporopollenin extracted from Antarctic Eocene SHALDRIL cores from ~35.9 Mya, just prior to the E-O Boundary (Bohaty et al., 2011). We also analyzed δ13C of modern Nothofagus sporopollenin from herbaria specimens and related these results to historical climate data. Our modern data show that carbon isotope discrimination (Δ) of Nothofagus sporopollenin is positively correlated with mean annual and growing-season precipitation, consistent with prior studies that demonstrate a strong relationship between Δ and water availability in C3 plants. Eocene Nothofagus Δ values progressively decreased through time, implying a decline in moisture availability. There is a close correlation between Nothofagus palynomorph abundance (Warny and Askin, 2011) and Δ, indicating that Nothofagus abundance declined in response to decreasing moisture availability. We consider changes in sea surface temperatures as well as increased glaciation as possible causes

  16. Measuring changes in substrate utilization in the myocardium in response to fasting using hyperpolarized [1-13C]butyrate and [1-13C]pyruvate

    PubMed Central

    Bastiaansen, Jessica A. M.; Merritt, Matthew E.; Comment, Arnaud

    2016-01-01

    Cardiac dysfunction is often associated with a shift in substrate preference for ATP production. Hyperpolarized (HP) 13C magnetic resonance spectroscopy (MRS) has the unique ability to detect real-time metabolic changes in vivo due to its high sensitivity and specificity. Here a protocol using HP [1-13C]pyruvate and [1-13C]butyrate is used to measure carbohydrate versus fatty acid metabolism in vivo. Metabolic changes in fed and fasted Sprague Dawley rats (n = 36) were studied at 9.4 T after tail vein injections. Pyruvate and butyrate competed for acetyl-CoA production, as evidenced by significant changes in [13C]bicarbonate (−48%), [1-13C]acetylcarnitine (+113%), and [5-13C]glutamate (−63%), following fasting. Butyrate uptake was unaffected by fasting, as indicated by [1-13C]butyrylcarnitine. Mitochondrial pseudoketogenesis facilitated the labeling of the ketone bodies [1-13C]acetoacetate and [1-13C]β-hydroxybutyryate, without evidence of true ketogenesis. HP [1-13C]acetoacetate was increased in fasting (250%) but decreased during pyruvate co-injection (−82%). Combining HP 13C technology and co-administration of separate imaging agents enables noninvasive and simultaneous monitoring of both fatty acid and carbohydrate oxidation. This protocol illustrates a novel method for assessing metabolic flux through different enzymatic pathways simultaneously and enables mechanistic studies of the changing myocardial energetics often associated with disease. PMID:27150735

  17. Measuring changes in substrate utilization in the myocardium in response to fasting using hyperpolarized [1-(13)C]butyrate and [1-(13)C]pyruvate.

    PubMed

    Bastiaansen, Jessica A M; Merritt, Matthew E; Comment, Arnaud

    2016-01-01

    Cardiac dysfunction is often associated with a shift in substrate preference for ATP production. Hyperpolarized (HP) (13)C magnetic resonance spectroscopy (MRS) has the unique ability to detect real-time metabolic changes in vivo due to its high sensitivity and specificity. Here a protocol using HP [1-(13)C]pyruvate and [1-(13)C]butyrate is used to measure carbohydrate versus fatty acid metabolism in vivo. Metabolic changes in fed and fasted Sprague Dawley rats (n = 36) were studied at 9.4 T after tail vein injections. Pyruvate and butyrate competed for acetyl-CoA production, as evidenced by significant changes in [(13)C]bicarbonate (-48%), [1-(13)C]acetylcarnitine (+113%), and [5-(13)C]glutamate (-63%), following fasting. Butyrate uptake was unaffected by fasting, as indicated by [1-(13)C]butyrylcarnitine. Mitochondrial pseudoketogenesis facilitated the labeling of the ketone bodies [1-(13)C]acetoacetate and [1-(13)C]β-hydroxybutyryate, without evidence of true ketogenesis. HP [1-(13)C]acetoacetate was increased in fasting (250%) but decreased during pyruvate co-injection (-82%). Combining HP (13)C technology and co-administration of separate imaging agents enables noninvasive and simultaneous monitoring of both fatty acid and carbohydrate oxidation. This protocol illustrates a novel method for assessing metabolic flux through different enzymatic pathways simultaneously and enables mechanistic studies of the changing myocardial energetics often associated with disease. PMID:27150735

  18. Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C NMR spectroscopy (SIE-DOSY 13C NMR)

    NASA Astrophysics Data System (ADS)

    Vermillion, Karl; Price, Neil P. J.

    2009-06-01

    The feasibility of obtaining high quality homonuclear or heteronuclear diffusion-ordered 13C NMR data is shown to be greatly improved by using 13C isotopically-enriched samples. Stable isotope-enhanced diffusion ordered (SIE-DOSY) 13C NMR has been applied to 13C-enriched carbohydrates, and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, and a disaccharide and trisaccharide. These 2D spectra were obtained with as little as 8 min of acquisition time. Fully resolved 3D DOSY-HMQC NMR spectra of [U- 13C]xylose, [U- 13C]glucose, and [1- 13C gal]lactose were obtained in 5 h. Sample derivatization with [ carbonyl- 13C]acetate (peracetylation) extends the usefulness of the technique to included non-labeled sugars; the 13C-carbonyl - carbohydrate ring proton 1H- 13C correlations also provide additional structural information, as shown for the 3-D DOSY-HMQC analysis of a mixture of maltotriose and lactose per-[ carbonyl- 13C]acetates.

  19. Hepatic gluconeogenesis influences (13)C enrichment in lactate in human brain tumors during metabolism of [1,2-(13)C]acetate.

    PubMed

    Pichumani, Kumar; Mashimo, Tomoyuki; Vemireddy, Vamsidhara; Kovacs, Zoltan; Ratnakar, James; Mickey, Bruce; Malloy, Craig R; DeBerardinis, Ralph J; Bachoo, Robert M; Maher, Elizabeth A

    2016-07-01

    (13)C-enriched compounds are readily metabolized in human malignancies. Fragments of the tumor, acquired by biopsy or surgical resection, may be acid-extracted and (13)C NMR spectroscopy of metabolites such as glutamate, glutamine, 2-hydroxyglutarate, lactate and others provide a rich source of information about tumor metabolism in situ. Recently we observed (13)C-(13)C spin-spin coupling in (13)C NMR spectra of lactate in brain tumors removed from patients who were infused with [1,2-(13)C]acetate prior to the surgery. We found, in four patients, that infusion of (13)C-enriched acetate was associated with synthesis of (13)C-enriched glucose, detectable in plasma. (13)C labeled glucose derived from [1,2-(13)C]acetate metabolism in the liver and the brain pyruvate recycling in the tumor together lead to the production of the (13)C labeled lactate pool in the brain tumor. Their combined contribution to acetate metabolism in the brain tumors was less than 4.0%, significantly lower than the direct oxidation of acetate in the citric acid cycle in tumors. PMID:27020407

  20. New method for estimating bacterial cell abundances in natural samples by use of sublimation

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Cleaves, H. James; Schubert, Michael; Aubrey, Andrew; Bada, Jeffrey L.

    2004-01-01

    We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples, including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert, were heated to a temperature of 500 degrees C for several seconds under reduced pressure. The sublimate was collected on a cold finger, and the amount of adenine released from the samples was then determined by high-performance liquid chromatography with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approximately 10(5) to 10(9) E. coli cell equivalents per gram. For most of these samples, the sublimation-based cell counts were in agreement with total bacterial counts obtained by traditional DAPI (4,6-diamidino-2-phenylindole) staining.

  1. Micron-scale intra-ring analyses of δ13C in early Eocene Arctic wood from Ellesmere Island

    NASA Astrophysics Data System (ADS)

    Schubert, B.; Jahren, H.; Eberle, J.; Sternberg, L.

    2009-12-01

    Early Eocene (ca. 53 Ma) fossil assemblages on Ellesmere Island (75 oN paleolatitude), provide rich information about the plant and animal life of the lush polar ecosystems of the time. Fossil wood recovered from Ellesmere Island is abundant and not permineralized; however, morphological features such as growth rings and resin canals have been obliterated by compression. We report on exceptionally high-resolution intra-ring analyses of δ13C within fossil wood, sampled at ~30 micron intervals across several centimeters of wood sample. Clear patterns in systematic seasonal increases and decreases in wood δ13C allowed us to identify at least 5 annual cycles in the wood. The patterns of increase and decrease in δ13C were consistent with patterns observed for evergreen wood, and distinct from the deciduous patterns we have observed for Metasequoia fossil wood from the middle Eocene (ca. 45 Ma) Arctic site on Axel Heiberg Island. We believe that the high point in the δ13C value of wood seen in each cycle corresponds to the highest environmental temperatures during the annual cycle, as has been seen for modern evergreens (e.g., Barbour et al., 2002). Modern studies have also noted that high temperature periods are correlated with the highest vapor-pressure and soil-water deficits of the annual cycle; these environmental factors would cause the plant to change its discrimination during photosynthesis. We will discuss the relatively low amplitude of δ13C fluctuations (0.5-1.0 ‰) clearly defined by Ellesmere fossil wood, in comparison to observations on modern common evergreens (2.0-4.0 ‰), and speculate that this difference implies greatly dampened seasonal temperature fluctuations in Eocene polar environments, relative to today. Barbour M.M., Walcroft A.S., Farquhar G.D., 2002, Seasonal variation in δ13C and δ18O of cellulose from growth rings of Pinus radiata. Plant, Cell and Environment: v. 25, p. 1483-1499.

  2. Methanogenic calcite, 13C-depleted bivalve shells, and gas hydrate from a mud volcano offshore southern California

    USGS Publications Warehouse

    Hein, J.R.; Normark, W.R.; McIntyre, B.R.; Lorenson, T.D.; Powell, C.L., II

    2006-01-01

    Methane and hydrogen sulfide vent from a cold seep above a shallowly buried methane hydrate in a mud volcano located 24 km offshore southern California in?? 800 m of water. Bivalves, authigenic calcite, and methane hydrate were recovered in a 2.1 m piston core. Aragonite shells of two bivalve species are unusually depleted in 13C (to -91??? ??13C), the most 13C-depleted shells of marine macrofauna yet discovered. Carbon isotopes for both living and dead specimens indicate that they used, in part, carbon derived from anaerobically oxidized methane to construct their shells. The ??13C values are highly variable, but most are within the range -12??? to -91???. This variability may be diagnostic for identifying cold-seep-hydrate systems in the geologic record. Authigenic calcite is abundant in the cores down to ???1.5 m subbottom, the top of the methane hydrate. The calcite is depleted in 13C (??13C = -46??? to -58???), indicating that carbon produced by anaerobically oxidized methane is the main source of the calcite. Methane sources include a geologic hydrocarbon reservoir from Miocene source rocks, and biogenic and thermogenic degradation of organic matter in basin sediments. Oxygen isotopes indicate that most calcite formed out of isotopic equilibrium with ambient bottom water, under the influence of gas hydrate dissociation and strong methane flux. High metal content in the mud volcano sediment indicates leaching of basement rocks by fluid circulating along an underlying fault, which also allows for a high flux of fossil methane. ?? 2006 Geological Society of America.

  3. A thalium-doped sodium iodide well counter for radioactive tracer applications with naturally-abundant 40K

    NASA Astrophysics Data System (ADS)

    Parker, Andrew J.; Boxall, Colin; Joyce, Malcolm J.; Schotanus, Paul

    2013-09-01

    The use of a thallium-doped sodium-iodide well-type scintillation detector for the assay of the low-activity radioisotope 40K, in open-source potassium chloride aqueous solutions, is described. The hazards, safety concerns and radiowaste generation associated with using open-source radioactive isotopes can present significant difficulties, the use of hot cells and escalated costs in radioanalytical laboratory research. A solution to this is the use of low-hazard alternatives that mimic the migration and dispersion characteristics of notable fission products (in this case 137Cs). The use of NaI(Tl) as a detection medium for naturally-abundant levels of 40K in a range of media is widespread, but the use of 40K as a radioactive tracer has not been reported. The use of such low-activity sources is often complicated by the ability to detect them efficiently. In this paper a scintillator detector designed to detect the naturally-abundant 40K present in potassium chloride in tracer applications is described. Examples of the use of potassium chloride as a tracer are given in the context of ion exchange and electrochemical migration studies, and comparisons in performance are drawn from literature with hyper pure germanium semiconductor detectors, which are more commonly utilised detectors in high-resolution counting applications.

  4. Dynamic Nuclear Polarization NMR Enables the Analysis of Sn-Beta Zeolite Prepared with Natural Abundance 119Sn Precursors

    PubMed Central

    2015-01-01

    The catalytic activity of tin-containing zeolites, such as Sn-Beta, is critically dependent on the successful incorporation of the tin metal center into the zeolite framework. However, synchrotron-based techniques or solid-state nuclear magnetic resonance (ssNMR) of samples enriched with 119Sn isotopes are the only reliable methods to verify framework incorporation. This work demonstrates, for the first time, the use of dynamic nuclear polarization (DNP) NMR for characterizing zeolites containing ∼2 wt % of natural abundance Sn without the need for 119Sn isotopic enrichment. The biradicals TOTAPOL, bTbK, bCTbK, and SPIROPOL functioned effectively as polarizing sources, and the solvent enabled proper transfer of spin polarization from the radical’s unpaired electrons to the target nuclei. Using bCTbK led to an enhancement (ε) of 75, allowing the characterization of natural-abundance 119Sn-Beta with excellent signal-to-noise ratios in <24 h. Without DNP, no 119Sn resonances were detected after 10 days of continuous analysis. PMID:24697321

  5. Inferring the nature of anthropogenic threats from long-term abundance records.

    PubMed

    Shoemaker, Kevin T; Akçakaya, H Resit

    2015-02-01

    Diagnosing the processes that threaten species persistence is critical for recovery planning and risk forecasting. Dominant threats are typically inferred by experts on the basis of a patchwork of informal methods. Transparent, quantitative diagnostic tools would contribute much-needed consistency, objectivity, and rigor to the process of diagnosing anthropogenic threats. Long-term census records, available for an increasingly large and diverse set of taxa, may exhibit characteristic signatures of specific threatening processes and thereby provide information for threat diagnosis. We developed a flexible Bayesian framework for diagnosing threats on the basis of long-term census records and diverse ancillary sources of information. We tested this framework with simulated data from artificial populations subjected to varying degrees of exploitation and habitat loss and several real-world abundance time series for which threatening processes are relatively well understood: bluefin tuna (Thunnus maccoyii) and Atlantic cod (Gadus morhua) (exploitation) and Red Grouse (Lagopus lagopus scotica) and Eurasian Skylark (Alauda arvensis) (habitat loss). Our method correctly identified the process driving population decline for over 90% of time series simulated under moderate to severe threat scenarios. Successful identification of threats approached 100% for severe exploitation and habitat loss scenarios. Our method identified threats less successfully when threatening processes were weak and when populations were simultaneously affected by multiple threats. Our method selected the presumed true threat model for all real-world case studies, although results were somewhat ambiguous in the case of the Eurasian Skylark. In the latter case, incorporation of an ancillary source of information (records of land-use change) increased the weight assigned to the presumed true model from 70% to 92%, illustrating the value of the proposed framework in bringing diverse sources of

  6. Forward Modeling of Fluctuating Dietary 13C Signals to Validate 13C Turnover Models of Milk and Milk Components from a Diet-Switch Experiment

    PubMed Central

    Braun, Alexander; Schneider, Stephan; Auerswald, Karl; Bellof, Gerhard; Schnyder, Hans

    2013-01-01

    Isotopic variation of food stuffs propagates through trophic systems. But, this variation is dampened in each trophic step, due to buffering effects of metabolic and storage pools. Thus, understanding of isotopic variation in trophic systems requires knowledge of isotopic turnover. In animals, turnover is usually quantified in diet-switch experiments in controlled conditions. Such experiments usually involve changes in diet chemical composition, which may affect turnover. Furthermore, it is uncertain if diet-switch based turnover models are applicable under conditions with randomly fluctuating dietary input signals. Here, we investigate if turnover information derived from diet-switch experiments with dairy cows can predict the isotopic composition of metabolic products (milk, milk components and feces) under natural fluctuations of dietary isotope and chemical composition. First, a diet-switch from a C3-grass/maize diet to a pure C3-grass diet was used to quantify carbon turnover in whole milk, lactose, casein, milk fat and feces. Data were analyzed with a compartmental mixed effects model, which allowed for multiple pools and intra-population variability, and included a delay between feed ingestion and first tracer appearance in outputs. The delay for milk components and whole milk was ∼12 h, and that of feces ∼20 h. The half-life (t½) for carbon in the feces was 9 h, while lactose, casein and milk fat had a t½ of 10, 18 and 19 h. The 13C kinetics of whole milk revealed two pools, a fast pool with a t½ of 10 h (likely representing lactose), and a slower pool with a t½ of 21 h (likely including casein and milk fat). The diet-switch based turnover information provided a precise prediction (RMSE ∼0.2 ‰) of the natural 13C fluctuations in outputs during a 30 days-long period when cows ingested a pure C3 grass with naturally fluctuating isotope composition. PMID:24392000

  7. A New Method for Estimating Bacterial Abundances in Natural Samples using Sublimation

    NASA Technical Reports Server (NTRS)

    Glavin, Daniel P.; Cleaves, H. James; Schubert, Michael; Aubrey, Andrew; Bada, Jeffrey L.

    2004-01-01

    We have developed a new method based on the sublimation of adenine from Escherichia coli to estimate bacterial cell counts in natural samples. To demonstrate this technique, several types of natural samples including beach sand, seawater, deep-sea sediment, and two soil samples from the Atacama Desert were heated to a temperature of 500 C for several seconds under reduced pressure. The sublimate was collected on a cold finger and the amount of adenine released from the samples then determined by high performance liquid chromatography (HPLC) with UV absorbance detection. Based on the total amount of adenine recovered from DNA and RNA in these samples, we estimated bacterial cell counts ranging from approx. l0(exp 5) to l0(exp 9) E. coli cell equivalents per gram. For most of these samples, the sublimation based cell counts were in agreement with total bacterial counts obtained by traditional DAPI staining. The simplicity and robustness of the sublimation technique compared to the DAPI staining method makes this approach particularly attractive for use by spacecraft instrumentation. NASA is currently planning to send a lander to Mars in 2009 in order to assess whether or not organic compounds, especially those that might be associated with life, are present in Martian surface samples. Based on our analyses of the Atacama Desert soil samples, several million bacterial cells per gam of Martian soil should be detectable using this sublimation technique.

  8. The use of isotope ratios (13C/12C) for vegetable oils authentication

    NASA Astrophysics Data System (ADS)

    Cristea, G.; Magdas, D. A.; Mirel, V.

    2012-02-01

    Stable isotopes are now increasingly used for the control of the geographical origin or authenticity of food products. The falsification may be more or less sophisticated and its sophistication as well as its costs increases with the improvement of analytical methods. In this study 22 vegetable oils (olive, sunflower, palm, maize) commercialized on Romanian market were investigated by mean of δ13C in bulk oil and the obtained results were compared with those reported in literature in order to check the labeling of these natural products. The obtained results were in the range of the mean values found in the literature for these types of oils, thus providing their accurate labeling.

  9. Changes and their possible causes in δ13C of dark-respired CO2 and its putative bulk and soluble sources during maize ontogeny.

    PubMed

    Ghashghaie, Jaleh; Badeck, Franz W; Girardin, Cyril; Huignard, Christophe; Aydinlis, Zackarie; Fonteny, Charlotte; Priault, Pierrick; Fresneau, Chantal; Lamothe-Sibold, Marlène; Streb, Peter; Terwilliger, Valery J

    2016-04-01

    The issues of whether, where, and to what extent carbon isotopic fractionations occur during respiration affect interpretations of plant functions that are important to many disciplines across the natural sciences. Studies of carbon isotopic fractionation during dark respiration in C3 plants have repeatedly shown respired CO2 to be (13)C enriched relative to its bulk leaf sources and (13)C depleted relative to its bulk root sources. Furthermore, two studies showed respired CO2 to become progressively (13)C enriched during leaf ontogeny and (13)C depleted during root ontogeny in C3 legumes. As such data on C4 plants are scarce and contradictory, we investigated apparent respiratory fractionations of carbon and their possible causes in different organs of maize plants during early ontogeny. As in the C3 plants, leaf-respired CO2 was (13)C enriched whereas root-respired CO2 was (13)C depleted relative to their putative sources. In contrast to the findings for C3 plants, however, not only root- but also leaf-respired CO2 became more (13)C depleted during ontogeny. Leaf-respired CO2 was highly (13)C enriched just after light-dark transition but the enrichment rapidly decreased over time in darkness. We conclude that (i) although carbon isotopic fractionations in C4 maize and leguminous C3 crop roots are similar, increasing phosphoenolpyruvate-carboxylase activity during maize ontogeny could have produced the contrast between the progressive (13)C depletion of maize leaf-respired CO2 and (13)C enrichment of C3 leaf-respired CO2 over time, and (ii) in both maize and C3 leaves, highly (13)C enriched leaf-respired CO2 at light-to-dark transition and its rapid decrease during darkness, together with the observed decrease in leaf malate content, may be the result of a transient effect of light-enhanced dark respiration. PMID:26970389

  10. Study of the metabolism of /sup 13/C labeled substrates by /sup 13/C NMR spectroscopy of intact cells, tissues, and organs

    SciTech Connect

    Matwiyoff, N.A.; London, R.E.; Hutson, J.Y.

    1982-01-01

    Carbon-13 nuclear magnetic resonance spectroscopy, in conjunction with carbon-13 labeling, has become an important analytical technique for the study of biological systems and biologically important molecules. The growing list of its well established applications to isolated molecules in solution includes the investigation of: metabolic pathways; the microenvironments of ligands bound to proteins; the architecture and dynamics of macromolecules; the structures of coenzymes and other natural products; and the mechanisms of reactions. Recently interest has been reawakened in the use of the technique for the study of metabolic pathways and structural components in intact organelles, cells, and tissues. The promise and problems in the use of /sup 13/C labeling in such investigations can be illustrated by the results on suspensions of the yeast, Candida utilis.

  11. Spectroscopic separation of (13) C NMR spectra of complex isomeric mixtures by the CSSF-TOCSY-INEPT experiment.

    PubMed

    Yang, Lu; Moreno, Aitor; Fieber, Wolfgang; Brauchli, Robert; Sommer, Horst

    2015-04-01

    Isomeric mixtures from synthetic or natural origins can pose fundamental challenges for their chromatographic separation and spectroscopic identification. A novel 1D selective NMR experiment, chemical shift selective filter (CSSF)-TOCSY-INEPT, is presented that allows the extraction of (13) C NMR subspectra of discrete isomers in complex mixtures without physical separation. This is achieved via CSS excitation of proton signals in the (1) H NMR mixture spectrum, propagation of the selectivity by polarization transfer within coupled (1) H spins, and subsequent relaying of the magnetization from (1) H to (13) C by direct INEPT transfer to generate (13) C NMR subspectra. Simple consolidation of the subspectra yields (13) C NMR spectra for individual isomers. Alternatively, CSSF-INEPT with heteronuclear long-range transfer can correlate the isolated networks of coupled spins and therefore facilitate the reconstruction of the (13) C NMR spectra for isomers containing multiple spin systems. A proof-of-principle validation of the CSSF-TOCSY-INEPT experiment is demonstrated on three mixtures with different spectral and structural complexities. The results show that CSSF-TOCSY-INEPT is a versatile, powerful tool for deconvoluting isomeric mixtures within the NMR tube with unprecedented resolution and offers unique, unambiguous spectral information for structure elucidation. PMID:25616134

  12. 13C Nuclear Magnetic Resonance Study of Acetate Incorporation into Malate During Ca2+-Uptake by Isolated Leaf Tissues 1

    PubMed Central

    Borchert, Rolf; Everett, Grover W.

    1987-01-01

    13C Nuclear magnetic resonance spectroscopy of leaflets of Gleditsia triacanthos and Albizia julibrisin was used to determine the fate of acetate taken up during the absorption of calcium from 13C-labeled Ca-acetate solution. Small amounts of acetate accumulated temporarily in the leaf tissues, but the bulk of acetate was incorporated into malate. The initial rate of malate synthesis was very low, but increased rapidly during acetate treatment and reached its maximum after 8 hours; the enzymes involved in malate synthesis thus appear to be substrate induced. Use of acetate-2-13C yielded malate labeled in C-3, indicating that vacuolar malate accumulating during Ca-uptake might be synthesized via malate synthase from acetate and glyoxalate. However, a source of glyoxalate condensing with acetate during malate synthesis could not be identified. Glycolate produced in photorespiration is an unlikely source, because glycolate-2-13C was absorbed and metabolized by the leaf tissues into products of the glycolate pathway, but was not a major precursor in malate synthesis. Malate synthesis via the glyoxalate cycle is also unlikely, because no evidence for the recycling of a 13C-labeled 4-carbon organic acid was found. Malate synthesis in the leaflets of Gleditsia and Albizia thus appears to involve the inducible condensation of acetate with a 2-carbon compound of unidentified nature and origin. PMID:16665548

  13. The 4051 Å Comet Band of 13C3

    NASA Astrophysics Data System (ADS)

    Haddad, M. A.; Zhao, D.; Linnartz, H.; Ubachs, W.

    2014-02-01

    The tricarbon C3 molecule has been detected in a number of translucent interstellar clouds via its $A^1\\Piu-X^1\\Sigmag+$ (000-000) electronic `comet' band around 4051 Å. So far, it is the largest molecule unambiguously identified in the diffuse interstellar medium. In this work, rotationally resolved laboratory spectra are presented for the corresponding transition of the 13C3 isotopologue. The spectra are recorded in direct absorption using cavity ring-down spectroscopy in combination with a supersonic plasma jet. A rotational analysis yields accurate spectroscopic parameters. In contrast to 12C3, no significant perturbations are found for (e- or f-parity) levels up to J' = 18 in the A 1Π upper electronic state.

  14. Σ production from targets of ^4He and ^13C

    NASA Astrophysics Data System (ADS)

    Chrien, R. E.

    1996-10-01

    One of the abiding issues in hypernuclear research has been the question of the formation of nuclear bound states incorporating the Σ-hyperon. The recent increases in beam intensity at the Brookhaven AGS have enabled us to obtain a high statistics study on the production of Σ-hyperons on a ^4He target. Earlier research using stopped kaons at KEK indicated the presence of structure in the (K^-,π^-) reaction, and led to the postulate of a Σ bound state. That structure has now been definitely confirmed in the in-flight kaon experiment at the LESB2 beam line and Moby-Dick spectrometer. An improved measurement of the binding energy of the presumed state will be reported, together with a production cross section. In addition, both (K^-,π^-) and (K^-,π^+) reactions on ^13C have been studied and will be compared to similar measurements on ^9Be.

  15. Multiscale computational modeling of (13)C DNP in liquids.

    PubMed

    Küçük, Sami Emre; Sezer, Deniz

    2016-04-14

    Dynamic nuclear polarization (DNP) enables the substantial enhancement of the NMR signal intensity in liquids. While proton DNP is dominated by the dipolar interaction between the electron and nuclear spins, the Fermi contact (scalar) interaction is equally important for heavier nuclei. The impossibility to predict the magnitude and field dependence of the scalar contribution hampers the application of high-field DNP to nuclei other than (1)H. We demonstrate that molecular dynamics (MD) simulations followed by density functional calculations of the Fermi contacts along the MD trajectory lead to quantitative agreement with the DNP coupling factors of the methyl and carbonyl carbons of acetone in water at 0.35 T. Thus, the accurate calculation of scalar-dominated DNP enhancement at a desired magnetic field is demonstrated for the first time. For liquid chloroform at fields above 9 T, our methodology predicts direct (13)C DNP enhancements that are two orders of magnitude larger than those of (1)H. PMID:27001446

  16. Historical oceanographic events reflected in13C/12C ratio of total organic carbon in laminated Santa Barbara Basin Sediment

    NASA Astrophysics Data System (ADS)

    Schimmelmann, Arndt; Tegner, Mia J.

    1991-06-01

    An 1844-1987 time series of carbon stable isotope ratios from dated sedimentary total organic carbon (TOC) from the center of the Santa Barbara Basin (SBB) is compared with historical climate and oceanographic records. Four isotopically distinct biogeochemical sources of TOC are important: phytoplankton-derived marine biomass, macroalgal biomass from kelp forests, terrigenous biomass (mainly flushed into the SBB via river discharge), and redeposited fossil organic carbon. The significance of the latter two sources is largely limited to a few unusual flood and oil spill events, whereas the combination of 13C-depleted phytoplankton and 13C-enriched macroalgal biomass appears to be responsible for most of the isotopic variance of the marine coastal biomass as recorded in sedimentary TOC. The isotopic response of marine organic carbon in sediments records strong El Niño-Southern Oscillation (ENSO) and the frequently associated severe storm and wave events in SBB varved sediments. The plausible major isotopic mechanisms are (1) increased physical liberation of 13C-enriched kelp carbon from locally abundant giant kelp (Macrocystis spp.) forests during times of physical and environmental stress, and (2) decreased productivity of 13C-depleted phytoplankton during ENSO events.

  17. Hyperpolarized (13)C Magnetic Resonance and Its Use in Metabolic Assessment of Cultured Cells and Perfused Organs.

    PubMed

    Lumata, Lloyd; Yang, Chendong; Ragavan, Mukundan; Carpenter, Nicholas; DeBerardinis, Ralph J; Merritt, Matthew E

    2015-01-01

    Diseased tissue is often characterized by abnormalities in intermediary metabolism. Observing these alterations in situ may lead to an improved understanding of pathological processes and novel ways to monitor these processes noninvasively in human patients. Although (13)C is a stable isotope safe for use in animal models of disease as well as human subjects, its utility as a metabolic tracer has largely been limited to ex vivo analyses employing analytical techniques like mass spectrometry or nuclear magnetic resonance spectroscopy. Neither of these techniques is suitable for noninvasive metabolic monitoring, and the low abundance and poor gyromagnetic ratio of conventional (13)C make it a poor nucleus for imaging. However, the recent advent of hyperpolarization methods, particularly dynamic nuclear polarization (DNP), makes it possible to enhance the spin polarization state of (13)C by many orders of magnitude, resulting in a temporary amplification of the signal sufficient for monitoring kinetics of enzyme-catalyzed reactions in living tissue through magnetic resonance spectroscopy or magnetic resonance imaging. Here, we review DNP techniques to monitor metabolism in cultured cells, perfused hearts, and perfused livers, focusing on our experiences with hyperpolarized [1-(13)C]pyruvate. We present detailed approaches to optimize the DNP procedure, streamline biological sample preparation, and maximize detection of specific metabolic activities. We also discuss practical aspects in the choice of metabolic substrates for hyperpolarization studies and outline some of the current technical and conceptual challenges in the field, including efforts to use hyperpolarization to quantify metabolic rates in vivo. PMID:26358902

  18. Thz Spectroscopy of 13C Isotopic Species of a "weed": Acetaldehyde

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.

    2011-06-01

    Our studies of the isotopic species of 13C and D isotopologues of methyl formate (HCOOCH_3), have allowed the detection of more than 600 lines in Orion. This confirms that many observed U-lines are coming from isotopic species of one of the most abundant molecules in space. Since its first detection in 1976 in SgrB2 and in Orion A, acetaldehyde (CH_3CHO) was detected in many other numerous objects. If its deuterated species (CD_3CHO and CH_3CDO) have been previously studied in the millimeterwave range, the data concerning the 13C species are limited to few lines measured in 1957 up to 40 GHz. In this context we decided to study the 13C species of acetaldehyde. Acetaldehyde molecule displays a large amplitude motion: the hindered rotation of the methyl group with respect to the rest of the molecule. The analysis is performed with the Rho Axis Method. Recent versions of the codes include high orders term in order to reproduce the observed frequencies for large quantum numbers values as J-values as high as 70a,b,. Measurements and analysis of the rotational spectra of 13C isotopic species are in progress in Lille with a solid-state submillimetre-wave spectrometer (50-950 GHz), the first results will be presented. This work is supported by the contract ANR-08-BLAN-0054 and by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS). Carvajal, M.; Margulès, L.; Tercero, B.; et al.A&A 500, (2009) 1109 Margulès, L.; Huet, T. R.; Demaison J.; et al.,ApJ 714, (2010) 1120. Ikeda, M.; Ohishi, M.; Nummelin, A.; et al., ApJ, 560, (2001) 792 Kleiner, I.; Lopez, J.-C.; Blanco, S.; et al.J. Mol. Spectrosc. 197, (1999) 275 Elkeurti M.; Coudert, L. H.; Medvedev, I. R.; et al.J. Mol. Spectrosc. 263, (2010) 145 Kilb, R.W.; Lin, C.C.; and Wilson, E.B.J. Chem. Phys. 26, (1957) 1695 Kleiner, I. J. Mol. Spectrosc. 260, (2010) 1 Ilyushin, V.V.; Kryvda, A; and Alekseev, E;J. Mol. Spectrosc. 255, (2009) 32

  19. Prospective Work for Alma: the Millimeterwave and Submillimeterwave Spectrum of 13C-GLYCOLALDEHYDE

    NASA Astrophysics Data System (ADS)

    Haykal, Imane; Margulès, Laurent; Huet, Therese R.; Motiyenko, Roman; Guillemin, J.-C.

    2011-06-01

    Glycolaldehyde has been identified in interstellar sources. The relative abundance ratios of the three isomers (acetic acid) : (glycolaldehyde) : (methylformate) were estimated . The detection of 13C_1 and 13C_2 isotopomers of methylformate has been recently reported in Orion, as a result of the detailled labororatory spectroscopic study. Therefore the spectroscopy of the 13C isotopomers of glycolaldehyde is investigated in laboratory in order to provide data for an astronomical search. The instrument ALMA will certainly be a good instrument to detect them. Up to now, only the microwave spectra of 13CH_2OH-CHO and of CH_2OH-13CHO have been observed several years ago in the 12-40 GHz range. Spectra of both species are presently recorded in Lille in the 150-950 GHz range with the new submillimetre-wave spectrometer based on harmonic generation of a microwave synthesizer source, using only solid-state devices, and coupled to a cell of 2.2 m length The absolute accuracy of the line positions is better than 30 KHz. The rotational structure of the ground state and of the three first excited vibrational states has been observed. Two 13C enriched samples were used. The analysis is in progress. This work is supported by the Programme National de Physico-Chimie du Milieu Interstellaire (PCMI-CNRS) and by the contract ANR-08-BLAN-0054 J. M. Hollis, S. N. Vogel, L. E. Snyder, et al., Astrophys. J. 554(2001) L81 R. A. H. Butler, F. C. De Lucia, D. T Petkie, et al., Astrophys. J. Supp. 134 (2001) 319 M. T. Beltran, C. Codella, S. Viti, R. Niri, R. Cesaroni, Astrophys. J. 690 (2009) L93. M. Carjaval, L. Margulès, B. Tercero et al., Astron. Astrophys. 500 (2009) 1109. K.-M. Marstokk and H. Møllendal, J. Mol. Struct. 16 (1973) 259. R. A. Motiyenko, L. Margulès, E. A. Alekseev et al., J. Mol. Spectrosc. 264 (2010) 94.

  20. Millimeter and submillimeter wave spectra of 13C-glycolaldehydes

    NASA Astrophysics Data System (ADS)

    Haykal, I.; Motiyenko, R. A.; Margulès, L.; Huet, T. R.

    2013-01-01

    Context. Glycolaldehyde (CH2OHCHO) is the simplest sugar and an important intermediate in the path toward forming more complex biologically relevant molecules. Astronomical surveys of interstellar molecules, such as those available with the very sensitive ALMA telescope, require preliminary laboratory investigations of the microwave and submillimeter-wave spectra of molecular species including new isotopologs - to identify these in the interstellar media. Aims: To achieve the detection of the 13C isotopologs of glycolaldehyde in the interstellar medium, their rotational spectra in the millimeter and submillimeter-wave regions were studied. Methods: The spectra of 13CH2OHCHO and CH2OH13CHO were recorded in the 150-945 GHz spectral range in the laboratory using a solid-state submillimeter-wave spectrometer in Lille. The observed line frequencies were measured with an accuracy of 30 kHz up to 700 GHz and of 50 kHz above 700 GHz. We analyzed the spectra with a standard Watson Hamiltonian. Results: About 10 000 new lines were identified for each isotopolog. The spectroscopic parameters were determined for the ground- and the three lowest vibrational states up to 945 and 630 GHz. Previous microwave assignments of 13CH2OHCHO were not confirmed. Conclusions: The provided line-lists and sets of molecular parameters meet the needs for a first astrophysical search of 13C-glycolaldehydes. Full Tables 3 and 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/549/A96

  1. The post-Paleozoic chronology and mechanism of 13C depletion in primary marine organic matter

    NASA Technical Reports Server (NTRS)

    Popp, B. N.; Takigiku, R.; Hayes, J. M.; Louda, J. W.; Baker, E. W.

    1989-01-01

    Carbon-isotopic compositions of geoporphyrins have been measured from marine sediments of Mesozoic and Cenozoic age in order to elucidate the timing and extent of depletion of 13C in marine primary producers. These results indicate that the difference in isotopic composition of coeval marine carbonates and marine primary photosynthate was approximately 5 to 7 permil greater during the Mesozoic and early Cenozoic than at present. In contrast to the isotopic record of marine primary producers, isotopic compositions of terrestrial organic materials have remained approximately constant for this same interval of time. This difference in the isotopic records of marine and terrestrial organic matter is considered in terms of the mechanisms controlling the isotopic fractionation associated with photosynthetic fixation of carbon. We show that the decreased isotopic fractionation between marine carbonates and organic matter from the Early to mid-Cenozoic may record variations in the abundance of atmospheric CO2.

  2. The First in Vivo Observation of 13C- 15N Coupling in Mammalian Brain

    NASA Astrophysics Data System (ADS)

    Kanamori, Keiko; Ross, Brian D.

    2001-12-01

    [5-13C,15N]Glutamine, with 1J(13C-15N) of 16 Hz, was observed in vivo in the brain of spontaneously breathing rats by 13C MRS at 4.7 T. The brain [5-13C]glutamine peak consisted of the doublet from [5-13C,15N]glutamine and the center [5-13C,14N]glutamine peak, resulting in an apparent triplet with a separation of 8 Hz. The time course of formation of brain [5-13C,15N]glutamine was monitored in vivo with a time resolution of 20-35 min. This [5-13C,15N]glutamine was formed by glial uptake of released neurotransmitter [5-13C]glutamate and its reaction with 15NH3 catalyzed by the glia-specific glutamine synthetase. The neurotransmitter glutamate C5 was selectively13C-enriched by intravenous [2,5-13C]glucose infusion to 13C-label whole-brain glutamate C5, followed by [12C]glucose infusion to chase 13C from the small and rapidly turning-over glial glutamate pool, leaving 13C mainly in the neurotransmitter [5-13C]glutamate pool, which is sequestered in vesicles until release. Hence, the observed [5-13C,15N]glutamine arises from a coupling between 13C of neuronal origin and 15N of glial origin. Measurement of the rate of brain [5-13C,15N]glutamine formation provides a novel noninvasive method of studying the kinetics of neurotransmitter uptake into glia in vivo, a process that is crucial for protecting the brain from glutamate excitotoxicity.

  3. Rapid detection and characterization of surface CO2 leakage through the real-time measurement of δ13C signatures in CO2 flux from the ground

    NASA Astrophysics Data System (ADS)

    Krevor, S.; Perrin, J.; Esposito, A.; Rella, C.; Benson, S. M.

    2009-12-01

    A portable stable carbon isotope ratio analyzer for carbon dioxide, based on wavelength scanned cavity ringdown spectroscopy, has been used to detect and characterize an intentional leakage of CO2 from an underground pipeline at the ZERT experimental facility in Bozeman, Montana. Rapid (~1 hour) walking surveys of the entire 100m x 100m site were collected using this mobile, real-time instrument. The resulting concentration and 13C isotopic abundance maps were processed using simple yet powerful analysis techniques, permitting not only the identification of specific leakage locations, but providing the ability to distinguish petrogenic sources of CO2 from biogenic sources. At the site an approximately 100-meter horizontal well has been drilled below an alfalfa field at a depth between 1-3 meters below the surface. The well has perforations along the central 70 meters of the well. The overlying strata are highly permeable sand, silt, and topsoil. The flora consists generally of long grasses and was cut to a height of less than 6 inches before the start of the experiment. For 30 days starting July 15, 2009, CO2 was injected at a rate of 0.2 tonnes per day. The injection rate is designed to simulate leakage from a mature storage reservoir at an annual rate of between .001 and .01%. The isotopic composition of the gas from the tank is at δ13C signature of approximately -52‰, far more negative than either atmospheric (approx. -8‰) or CO2 from soil respiration (approx. -26‰) at the site. The CO2 isotopic and concentration measurements were taken with a Picarro WS-CRDS analyzer with 1/8” tubing connected to a sampling inlet. Simultaneous with CO2 concentrations (including 13C), position data was logged using a GPS receiver. Datapoints are taken around every second. The analyzer was powered using batteries and housed in a conventional garden cart. The surveys consisted of traverses of the site along the length of the pipeline and extending out 100 meters on either

  4. Natural landscape and stream segment attributes influencing the distribution and relative abundance of riverine smallmouth bass in Missouri

    USGS Publications Warehouse

    Brewer, S.K.; Rabeni, C.F.; Sowa, S.P.; Annis, G.

    2007-01-01

    Protecting and restoring fish populations on a regional basis are most effective if the multiscale factors responsible for the relative quality of a fishery are known. We spatially linked Missouri's statewide historical fish collections to environmental features in a geographic information system, which was used as a basis for modeling the importance of landscape and stream segment features in supporting a population of smallmouth bass Micropterus dolomieu. Decision tree analyses were used to develop probability-based models to predict statewide occurrence and within-range relative abundances. We were able to identify the range of smallmouth bass throughout Missouri and the probability of occurrence within that range by using a few broad landscape variables: the percentage of coarse-textured soils in the watershed, watershed relief, and the percentage of soils with low permeability in the watershed. The within-range relative abundance model included both landscape and stream segment variables. As with the statewide probability of occurrence model, soil permeability was particularly significant. The predicted relative abundance of smallmouth bass in stream segments containing low percentages of permeable soils was further influenced by channel gradient, stream size, spring-flow volume, and local slope. Assessment of model accuracy with an independent data set showed good concordance. A conceptual framework involving naturally occurring factors that affect smallmouth bass potential is presented as a comparative model for assessing transferability to other geographic areas and for studying potential land use and biotic effects. We also identify the benefits, caveats, and data requirements necessary to improve predictions and promote ecological understanding. ?? Copyright by the American Fisheries Society 2007.

  5. High Resolution Spectrum of the 13C12C12C Lowest Bending Mode

    NASA Astrophysics Data System (ADS)

    Endres, C. P.; Lutter, V.; Kötting, J.; Krieg, J.; Thorwirth, S.; Schlemmer, S.; Giesen, T. F.; Harding, M. E.; Vazquez, J.

    2012-06-01

    Linear C_3 is a floppy molecule which possesses an extremely low lying bending mode, ν_2, at roughly 60 cm-1 or 1.9 THz. Based on highly accurate laboratory data C_3 has been detected in various astronomical sources most recently with the HIFI instrument aboard the Herschel satellite. Although C_3 turns out to be quite abundant in interstellar environments which makes a search for 13C substituted isotopologs feasible, other isotopologs could not be detected so far, because no accurate transition frequencies have been available for these species in this frequency range. Relative abundance ratios of C_3 isotopologs might give important hints on its building mechanism and further constraints for chemical networks. In this work, the spectrum of the ν_2 lowest bending mode of 13CCC has been investigated. We used laser ablation of 13C enriched carbon samples to record absorption spectra in a supersonic jet expansion. The radiation in our setup is generated by a synthesizer referenced to a Rubidium standard in combination with a frequency multiplier chain and detected by a liquid Helium cooled InSb bolometer. The laboratory search has been supported by high-level coupled-cluster calculations, which turns out to compare very favorably with obtained experimental molecular parameters. Schmuttenmaer, C. A., Cohen, R. C., Pugliano, N., Heath, et al., Science 249, 897-900 (1990) Giesen, T. F., van Orden, A. O., Cruzan, J. D., and Provencal, R. A., et al., Astrophys. J. 551, L181-L184 (2001) Gendriesch, R. and Pehl, K. and Giesen, T. and Winnewisser, G. and Lewen, F., Z. Naturforsch. 58a, 129-138 (2003) Van Orden, A., Cruzan, J. D., Provencal, R. A., et al. in Proc. Airborne Astronomy Symp., ASP Conf. Ser. 73, 67 (1995) ernicharo, J. and Goicoechea, J. R. and Caux, E., Astrophys. J. Lett. 534, L199-L202 (2000) Mookerjea, B., Giesen, T., Stutzki, J., Cernicharo, J., et al., Astron. Astrophys. 521, L13 (2010)

  6. Co-utilization of glucose and xylose by evolved Thermus thermophilus LC113 strain elucidated by (13)C metabolic flux analysis and whole genome sequencing.

    PubMed

    Cordova, Lauren T; Lu, Jing; Cipolla, Robert M; Sandoval, Nicholas R; Long, Christopher P; Antoniewicz, Maciek R

    2016-09-01

    We evolved Thermus thermophilus to efficiently co-utilize glucose and xylose, the two most abundant sugars in lignocellulosic biomass, at high temperatures without carbon catabolite repression. To generate the strain, T. thermophilus HB8 was first evolved on glucose to improve its growth characteristics, followed by evolution on xylose. The resulting strain, T. thermophilus LC113, was characterized in growth studies, by whole genome sequencing, and (13)C-metabolic flux analysis ((13)C-MFA) with [1,6-(13)C]glucose, [5-(13)C]xylose, and [1,6-(13)C]glucose+[5-(13)C]xylose as isotopic tracers. Compared to the starting strain, the evolved strain had an increased growth rate (~2-fold), increased biomass yield, increased tolerance to high temperatures up to 90°C, and gained the ability to grow on xylose in minimal medium. At the optimal growth temperature of 81°C, the maximum growth rate on glucose and xylose was 0.44 and 0.46h(-1), respectively. In medium containing glucose and xylose the strain efficiently co-utilized the two sugars. (13)C-MFA results provided insights into the metabolism of T. thermophilus LC113 that allows efficient co-utilization of glucose and xylose. Specifically, (13)C-MFA revealed that metabolic fluxes in the upper part of metabolism adjust flexibly to sugar availability, while fluxes in the lower part of metabolism remain relatively constant. Whole genome sequence analysis revealed two large structural changes that can help explain the physiology of the evolved strain: a duplication of a chromosome region that contains many sugar transporters, and a 5x multiplication of a region on the pVV8 plasmid that contains xylose isomerase and xylulokinase genes, the first two enzymes of xylose catabolism. Taken together, (13)C-MFA and genome sequence analysis provided complementary insights into the physiology of the evolved strain. PMID:27164561

  7. Stable isotope ratio (13C/12C) mass spectrometry to evaluate carbon sources and sinks: changes and trends during the decomposition of vegetal debris from eucalyptus clone plantations (NW Spain)

    NASA Astrophysics Data System (ADS)

    Fernandez, I.; Cabaneiro, A.

    2014-02-01

    Vegetal debris is known to participate in key soil processes such as the formation of soil organic matter (OM), also being a potential source of greenhouse gases to the atmosphere. However, its contribution to the isotopic composition of both the soil OM and the atmospheric carbon dioxide is not clear yet. Hence, the main objective of the present research is to understand the isotopic 13C changes and trends that take place during the successive biodegradative stages of decomposing soil organic inputs. By incubating bulk plant tissues for several months under laboratory controlled conditions, the kinetics of the CO2 releases and shifts in the 13C natural abundance of the solid residues were investigated using litter samples coming from forest plantations with a different clone (Anselmo: 1st clonal generation attained by morphological selection and Odiel: 2nd clonal generation genetically obtained) of Eucalyptus globulus Labill. developed over granitic or schistic bedrocks and located in northwestern Spain. Significant isotopic variations with time were observed, probably due to the isotopically heterogeneous composition of these complex substrates in conjunction with the initial selective consumption of more easily degradable 13C-differentiated compounds during the first stages of the biodegradation, while less available or recalcitrant litter components were decomposed at later stages of biodegradation, generating products that have their own specific isotopic signatures. These results, which significantly differ depending on the type of clone, suggest that caution must be exercised when interpreting carbon isotope studies (at natural abundance levels) since perturbations associated with the quality or chemical composition of the organic debris from different terrestrial ecosystems can have an important effect on the carbon stable isotope dynamics.

  8. Variation in Foliar δ13C of Desert Plant Reaumuria soongorica (Pall.) Maxim. among Different Environments in Northwestern China

    NASA Astrophysics Data System (ADS)

    Ma, J.; Pendall, E.; Chen, F.

    2008-12-01

    Reaumuria soongorica is a dominant desert shrub species in arid regions of northwest China, it playing an important role in the maintenance of the stability and continuity of desert ecosystem. The objectives of this study were to investigate the distribution characteristics of foliar δ13C value in R. soongorica, establish the correlations between foliar characteristics and environmental factors, and identify the major factor controlling the variations of foliar δ13C among different environments. Leaves of R. soongorica were collected from 21 natural populations in its major distribution area in northwestern China, across a range of mean annual precipitation from 27 to 328 mm, at altitudes from 394 to 1987 m above sea level, at latitudes from 36°N to 45°N and at longitudes from 81°E to 107°E. We measured the leaf nitrogen (LN), phosphorus (LP), potassium content (LK), leaf water content (LWC) and foliar δ13C in leaves of 407 individuals, and the soil physicochemical properties including nitrogen (SN), phosphorus (SP), soil organic matter (SOM), soil water contents (SWC) and total dissolved solids (TDS). Mean annual precipitation (MAP), mean annual temperature (MAT), evaporation, mean relative humidity (MRH) and duration of sunshine (DS), were collected from the Cold and Arid Environmental and Engineering Research Institute, Chinese Academy of Sciences. We observed that the foliar δ13C values increased significantly with the decreasing of MAP (r = -0.623, P = 0.003) and MRH(r = -0.702, P = 0.002), and decreased with decreasing DS and evaporation. No significant correlation with MAT was detected in δ13C values of R. soongorica. The correlations between foliar δ13C value and the soil factors demonstrated that the foliar δ13C values in R. soongorica significantly increased with the decreasing SWC (r = - 0.470, P = 0.037) and increasing TDS (r = 0.507, P = 0.022) in soil. There were no significant correlations between the foliar δ13C values and soil pH, total

  9. Measurement of position-specific 13C isotopic composition of propane at the nanomole level

    NASA Astrophysics Data System (ADS)

    Gilbert, Alexis; Yamada, Keita; Suda, Konomi; Ueno, Yuichiro; Yoshida, Naohiro

    2016-03-01

    We have developed a novel method for analyzing intramolecular carbon isotopic distribution of propane as a potential new tracer of its origin. The method is based on on-line pyrolysis of propane followed by analysis of carbon isotope ratios of the pyrolytic products methane, ethylene and ethane. Using propane samples spiked with 13C at the terminal methyl carbon, we characterize the origin of the pyrolytic fragments. We show that the exchange between C-atoms during the pyrolytic process is negligible, and thus that relative intramolecular isotope composition can be calculated. Preliminary data from 3 samples show that site-preference (SP) values, defined as the difference of δ13C values between terminal and sub-terminal C-atom positions of propane, range from -1.8‰ to -12.9‰. In addition, SP value obtained using our method for a thermogenic natural gas sample is consistent with that expected from theoretical models of thermal cracking, suggesting that the isotope fractionation associated with propane pyrolysis is negligible. The method will provide novel insights into the characterization of the origin of propane and will help better understand the biogeochemistry of natural gas deposits.

  10. Effects of weed cover composition on insect pest and natural enemy abundance in a field of Dracaena marginata (Asparagales: Asparagaceae) in Costa Rica.

    PubMed

    Sadof, Clifford S; Linkimer, Mildred; Hidalgo, Eduardo; Casanoves, Fernando; Gibson, Kevin; Benjamin, Tamara J

    2014-04-01

    Weeds and their influence on pest and natural enemy populations were studied on a commercial ornamental farm during 2009 in the Atlantic Zone of Costa Rica. A baseline survey of the entire production plot was conducted in February, along a 5 by 5 m grid to characterize and map initial weed communities of plants, cicadellids, katydids, and armored scales. In total, 50 plant species from 21 families were found. Seven weed treatments were established to determine how weed manipulations would affect communities of our targeted pests and natural enemies. These treatments were selected based on reported effects of specific weed cover on herbivorous insects and natural enemies, or by their use by growers as a cover crop. Treatments ranged from weed-free to being completely covered with endemic species of weeds. Although some weed treatments changed pest abundances, responses differed among arthropod pests, with the strongest effects observed for Caldwelliola and Empoasca leafhoppers. Removal of all weeds increased the abundance of Empoasca, whereas leaving mostly cyperacaeous weeds increased the abundance of Caldwelliola. Weed manipulations had no effect on the abundance of katydid and scale populations. No weed treatment reduced the abundance of all three of the target pests. Differential responses of the two leafhopper species to the same weed treatments support hypotheses, suggesting that noncrop plants can alter the abundance of pests through their effects on arthropod host finding and acceptance, as well as their impacts on natural enemies. PMID:24517852

  11. δ13C values of soil organic matter in semiarid grassland with mesquite (Prosopis) encroachment in southeastern Arizona

    USGS Publications Warehouse

    Biggs, Thomas H.; Quade, Jay; Webb, Robert H.

    2002-01-01

    Over the past century, C3 woody plants and trees have increased in abundance in many semiarid ecosystems, displacing native C4 grasses. Livestock grazing, climatic fluctuations, and fire suppression are several reasons proposed for this shift. Soil carbon isotopic signatures are an ideal technique to evaluate carbon turnover rates in such ecosystems. On the gunnery ranges of Fort Huachuca in southeastern Arizona, study sites were established on homogeneous granitic alluvium to investigate the effects of fire frequency on δ13C values in surface soil organic matter (SOM). These ranges have had no livestock grazing for 50 years and a well-documented history of fires. Prosopis velutina Woot. (mesquite) trees have altered SOM δ13C pools by the concentration of plant nutrients and the addition of isotopically light litter. These soil carbon changes do not extend beyond canopy margins. Elevated total organic carbon (TOC), plant nutrient (N and P) concentrations, and depleted SOM δ13C values are associated with C3Prosopis on an unburned plot, which enables recognition of former Prosopis-occupied sites on plots with recent fire histories. Elevated nutrient concentrations associated with former Prosopis are retained in SOM for many decades. Surface SOM δ13C values indicate the estimated minimum turnover time of C4-derived carbon beneath large mature Prosopis is about 100–300 years. In contrast, complete turnover of original C3 carbon to C4 carbon under grasslands is estimated to take a minimum of 150–500 years. Our study confirms that C4 grass cover has declined over the past 100 years, although isolated C3 trees or shrubs were not uncommon on the historic C4-dominated grasslands. We find evidence in surface soil layers for a modern C3 plant expansion reflected in the substantial shift of SOM δ13C values from C4 grasses to C3 shrublands.

  12. First Spectroscopic Studies and Detection in SgrB2 of 13C-DOUBLY Substitued Ethyl Cyanide

    NASA Astrophysics Data System (ADS)

    Margulès, L.; Motiyenko, R. A.; Guillemin, J.-C.; Müller, Holger S. P.; Belloche, Arnaud

    2015-06-01

    Ethyl cyanide (CH_3CH_2CN) is one of the most abundant complex organic molecules in the interstellar medium firstly detected in OMC-1 and Sgr B2 in 1977. The vibrationally excited states are enough populated under ISM conditions and could be detected. Apart from the deuterated ones, all mono-substituted isotopologues of ethyl cyanide (13C and 15N have been detected in the ISM. The detection of isotopologues in the ISM is important: it can give information about the formation process of complex organic molecules, and it is essential to clean the ISM spectra from the lines of known molecules in order to detect new ones. The 12C/13C ratio found in SgrB2: 20-30 suggests that the doubly 13C could be present in the spectral line survey recently obtained with ALMA (EMoCA), but no spectroscopic studies exist up to now. We measured and analyzed the spectra of the 13C-doubly-substitued species up to 1 THz with the Lille solid-state based spectrometer. The spectroscopic results and and the detection of the doubly 13C species in SgrB2 will be presented. This work was supported by the CNES and the Action sur Projets de l'INSU, PCMI. This work was also done under ANR-13-BS05-0008-02 IMOLABS. Support by the Deutsche Forschungsgemeinschaft via SFB 956, project B3 is acknowledged D.~R.~Johnson, et al., Astrophys.~J. 1977, 218, L370 A.~Belloche, et al., A&A 2013, 559, A47 A.M.~Daly, et al., Astrophys.~J. 2013, 768, 81 K.~Demyk, et al. A&A 2007 466, 255 Margulès, et al. A&A 2009, 493, 565 Belloche et al. 2014, Science, 345, 1584

  13. Thermal maturity of type II kerogen from the New Albany Shale assessed by13C CP/MAS NMR

    USGS Publications Warehouse

    Werner-Zwanziger, U.; Lis, G.; Mastalerz, Maria; Schimmelmann, A.

    2005-01-01

    Thermal maturity of oil and gas source rocks is typically quantified in terms of vitrinite reflectance, which is based on optical properties of terrestrial woody remains. This study evaluates 13C CP/MAS NMR parameters in kerogen (i.e., the insoluble fraction of organic matter in sediments and sedimentary rocks) as proxies for thermal maturity in marine-derived source rocks where terrestrially derived vitrinite is often absent or sparse. In a suite of samples from the New Albany Shale (Middle Devonian to the Early Mississippian, Illinois Basin) the abundance of aromatic carbon in kerogen determined by 13C CP/MAS NMR correlates linearly well with vitrinite reflectance. ?? 2004 Elsevier Inc. All rights reserved.

  14. Two Categories of 13C/12C Ratios for Higher Plants 1

    PubMed Central

    Smith, Bruce N.; Epstein, Samuel

    1971-01-01

    13C/12C ratios have been determined for plant tissue from 104 species representing 60 families. Higher plants fall into two categories, those with low δPDBI13C values (—24 to —34‰) and those with high δ 13C values (—6 to —19‰). Algae have δ 13C values of —12 to —23‰. Photosynthetic fractionation leading to such values is discussed. PMID:16657626

  15. Aspects regarding at 13C isotope separation column control using Petri nets system

    NASA Astrophysics Data System (ADS)

    Boca, M. L.; Ciortea, M. E.

    2015-11-01

    This paper is intended to show that Petri nets can be also applicable in the chemical industry. It used linear programming, modeling underlying Petri nets, especially discrete event systems for isotopic separation, the purpose of considering and control events in real-time through graphical representations. In this paper it is simulate the control of 13C Isotope Separation column using Petri nets. The major problem with 13C comes from the difficulty of obtaining it and raising its natural fraction. Carbon isotopes can be obtained using many methods, one of them being the cryogenic distillation of carbon monoxide. Some few aspects regarding operating conditions and the construction of such cryogenic plants are known today, and even less information are available as far as the separation process modeling and control are concerned. In fact, the efficient control of the carbon monoxide distillation process represents a necessity for large-scale 13C production. Referring to a classic distillation process, some models for carbon isotope separation have been proposed, some based on mass, component and energy balance equations, some on the nonlinear wave theory or the Cohen equations. For modeling the system it was used Petri nets because in this case it is deal with discrete event systems. In use of the non-timed and with auxiliary times Petri model, the transport stream was divided into sections and these sections will be analyzed successively. Because of the complexity of the system and the large amount of calculations required it was not possible to analyze the system as a unitary whole. A first attempt to model the system as a unitary whole led to the blocking of the model during simulation, because of the large processing times.

  16. 13C-18O bonding (Δ47) in deep-sea corals: a calibration study

    NASA Astrophysics Data System (ADS)

    Kimball, J. B.; Tripati, A.; Dunbar, R. B.; Eagle, R.

    2013-12-01

    Deep-sea corals are a potentially valuable archive of temperature in intermediate and deep waters, regions for which a paucity of temperature data exists. These archives could give valuable insight into the natural variability of areas of the ocean that play an active role in large-scale climate dynamics. Due to significant 'vital effects' (i.e., non-equilibrium mineral compositions) in δ18O, however, deep-sea coral have been challenging to develop as a paleotemperature proxy. Clumped-isotope paleothermometry is a new method that may circumvent some of the known complications with δ18O paleotemperature analysis in deep-sea coral. This geothermometer is based on the ordering of heavy 13C-18O ';clumps' in carbonate minerals. Initial calibration studies have shown that the method is independent from the solution chemistry of the precipitating fluids as well as 'vital effects' in deep-sea corals and other types of carbonates. Some kinetic effects have been observed in tropical corals and speleothems. Here we report new data in order to further develop clumped isotopes as a paleothermometer in deep-sea corals as well as to investigate taxon-specific effects. 13C-18O bond ordering was analyzed in live-collected scleractinian (Enallopsammia sp.) and gorgonian (Isididae and Coralliidae) deep-sea corals. We determined mass 47 anomalies in samples (Δ47), which refers to the parts per thousand excess of 13C-18O-16O in CO2 produced on acid digestion of a sample, relative to the amount predicted to be present if isotopes were randomly distributed amongst all CO2 isotopologues. Measured Δ47 values were compared to in situ temperatures and the relationship between Δ47 and temperature was determined for each group to investigate taxon-specific effects.

  17. 13C solid-state NMR analysis of heterogeneous structure of beeswax in native state

    NASA Astrophysics Data System (ADS)

    Kameda, Tsunenori

    2005-12-01

    I investigated the molecular structure of natural wax from Japanese bees (Apis cerana japonica) in its native state (neither purified nor recrystallized) by 13C and 1H solid-state NMR. Two strong 13C peaks at 32.9 and 34.0 ppm were attributed to signals from internal-chain methylene carbons [int-(CH2)] in two types of crystal form. The peak at 32.9 ppm was assigned to an orthorhombic crystal form, and that at 34.0 ppm was assigned to a triclinic or monoclinic form. In both crystalline regions, bi-exponential decay of 13C spin-lattice relaxation [T1(C)] for the crystalline peaks due to chain diffusion was observed. 1H spin-lattice relaxation [T1(H)] values for protons of the CH3 group and for int-(CH2) in the crystalline and amorphous regions were identical; this was interpreted as being due to averaging of the T1(H) relaxation rates via spin diffusion. In contrast, although the T_{{1}_{\\rho}}(H) decay curves for protons of the CH3 group and for int-(CH2) in the amorphous and orthorhombic forms were almost identical, those of the triclinic or monoclinic forms were different. This unhomogeneous character of T_{{1}_{\\rho}}(H) was interpreted as resulting from differences in the molecular composition of each crystal form. Moreover, two components with long and short 1H spin-spin relaxation [T2(H)] values, arising from the mobile and rigid phases, respectively, were observed at above about -30 °C.

  18. Relativistic Force Field: Parametrization of (13)C-(1)H Nuclear Spin-Spin Coupling Constants.

    PubMed

    Kutateladze, Andrei G; Mukhina, Olga A

    2015-11-01

    Previously, we reported a reliable DU8 method for natural bond orbital (NBO)-aided parametric scaling of Fermi contacts to achieve fast and accurate prediction of proton-proton spin-spin coupling constants (SSCC) in (1)H NMR. As sophisticated NMR experiments for precise measurements of carbon-proton SSCCs are becoming more user-friendly and broadly utilized by the organic chemistry community to guide and inform the process of structure determination of complex organic compounds, we have now developed a fast and accurate method for computing (13)C-(1)H SSCCs. Fermi contacts computed with the DU8 basis set are scaled using selected NBO parameters in conjunction with empirical scaling coefficients. The method is optimized for inexpensive B3LYP/6-31G(d) geometries. The parametric scaling is based on a carefully selected training set of 274 ((3)J), 193 ((2)J), and 143 ((1)J) experimental (13)C-(1)H spin-spin coupling constants reported in the literature. The DU8 basis set, optimized for computing Fermi contacts, which by design had evolved from optimization of a collection of inexpensive 3-21G*, 4-21G, and 6-31G(d) bases, offers very short computational (wall) times even for relatively large organic molecules containing 15-20 carbon atoms. The most informative SSCCs for structure determination, i.e., (3)J, were computed with an accuracy of 0.41 Hz (rmsd). The new unified approach for computing (1)H-(1)H and (13)C-(1)H SSCCs is termed "DU8c". PMID:26414291

  19. Inelastic pion scattering by /sup 13/C at low energies

    SciTech Connect

    Mitchell, J.H.

    1987-03-01

    Angular distributions for inelastically scattered pions were obtained for several states in /sup 13/C at an incident energy of 65 MeV. The data include results from both ..pi../sup +/ and ..pi../sup -/ measurements. In addition, ..pi../sup -/ measurements were made at T/sub ..pi../ = 50 MeV at one angle to give a two point fixed-q excitation function. The data are compared to theory and the data of others. As might be expected, medium corrections are shown to be considerably more important at low energies than at resonance. This is true for inelastic transitions of multipolarity 0,2 and 3. Parameters derived from an analysis of elastic pion scattering and SCX data also provide an adequate description of the inelastic transitions. The charge asymmetry in the cross sections for the 9/2/sup +/ state that was seen at resonance persists at these energies. This result is consistent with an impulse approximation treatment of the spin-flip amplitude. This is true even though the incoming energy of the pions is far below the range where the validity of an impulse treatment is expected. 65 refs., 45 figs.

  20. PASADENA hyperpolarization of 13C biomolecules: equipment design and installation

    PubMed Central

    Hövener, Jan-Bernd; Chekmenev, Eduard Y.; Harris, Kent C.; Perman, William H.; Robertson, Larry W.; Bhattacharya, Pratip

    2009-01-01

    Object The PASADENA method has achieved hyperpolarization of 16–20% (exceeding 40,000-fold signal enhancement at 4.7 T), in liquid samples of biological molecules relevant to in vivo MRI and MRS. However, there exists no commercial apparatus to perform this experiment conveniently and reproducibly on the routine basis necessary for translation of PASADENA to questions of biomedical importance. The present paper describes equipment designed for rapid production of six to eight liquid samples per hour with high reproducibility of hyperpolarization. Materials and methods Drawing on an earlier, but unpublished, prototype, we provide diagrams of a delivery circuit, a laminar-flow reaction chamber within a low field NMR contained in a compact, movable housing. Assembly instructions are provided from which a computer driven, semiautomated PASADENA polarizer can be constructed. Results Together with an available parahydrogen generator, the polarizer, which can be operated by a single investigator, completes one cycle of hyperpolarization each 52 s. Evidence of efficacy is presented. In contrast to competing, commercially available devices for dynamic nuclear polarization which characteristically require 90 min per cycle, PASADENA provides a low-cost alternative for high throughput. Conclusions This equipment is suited to investigators who have an established small animal NMR and wish to explore the potential of heteronuclear (13C and 15N) MRI, MRS, which harnesses the enormous sensitivity gain offered by hyperpolarization. PMID:19067008

  1. New optical analyzer for 13C-breath test

    NASA Astrophysics Data System (ADS)

    Harde, Hermann; Dressler, Matthias; Helmrich, Günther; Wolff, Marcus; Groninga, Hinrich

    2008-04-01

    Medical breath tests are well established diagnostic tools, predominantly for gastroenterological inspections, but also for many other examinations. Since the composition and concentration of exhaled volatile gases reflect the physical condition of a patient, a breath analysis allows one to recognize an infectious disease in an organ or even to identify a tumor. One of the most prominent breath tests is the 13C-urea-breath test, applied to ascertain the presence of the bacterium helicobacter pylori in the stomach wall as an indication of a gastric ulcer. In this contribution we present a new optical analyzer that is based on photoacoustic spectroscopy and uses a DFB diode laser at 2.744 μm. The concentration ratio of the CO II isotopologues is determined by measuring the absorption on a 13CO II line in comparison to a 12CO II line. In the specially selected spectral range the lines have similar strengths, although the concentrations differ by a factor of 90. Therefore, the signals are well comparable. Due to an excellent signal-noise-ratio isotope variations of less than 1% can be resolved as required for the breath test.

  2. Combined analysis of C-18 unsaturated fatty acids using natural abundance deuterium 2D NMR spectroscopy in chiral oriented solvents.

    PubMed

    Lesot, Philippe; Baillif, Vincent; Billault, Isabelle

    2008-04-15

    The quantitative determination of isotopic (2H/1H)i ratios at natural abundance using the SNIF-NMR protocol is a well-known method for understanding the enzymatic biosynthesis of metabolites. However, this approach is not always successful for analyzing large solutes and, specifically, is inadequate for prochiral molecules such as complete essential unsaturated fatty acids. To overcome these analytical limitations, we use the natural abundance deuterium 2D NMR (NAD 2D NMR) spectroscopy on solutes embedded in polypeptide chiral liquid crystals. This approach, recently explored for measuring (2H/1H)i ratios of small analytes (Lesot, P.; Aroulanda, C.; Billault, I. Anal. Chem. 2004, 76, 2827-2835), is a powerful way to separate the 2H signals of all nonequivalent enantioisotopomers on the basis both of the 2H quadrupolar interactions and of the 2H chemical shift. Two significant advances over our previous work are presented here and allow the complete isotopic analysis of four mono- and polyunsaturated fatty acid methyl esters: methyl oleate (1), methyl linoleate (2), methyl linolenate (3), and methyl vernoleate (4). The first consists of using NMR spectrometers operating at higher magnetic field strength (14.1 T) and equipped with a selective cryoprobe optimized for deuterium nuclei. The second is the development of Q-COSY Fz 2D NMR experiments able to produce phased 2H 2D maps after a double Fourier transformation. This combination of modern hardware and efficient NMR sequences provides a unique tool to analyze the (2H/1H)i ratios of large prochiral molecules (C-18) dissolved in organic solutions of poly(gamma-benzyl-L-glutamate) and requires smaller amounts of solute than previous study on fatty acids. For each compound (1-4), all 2H quadrupolar doublets visible in the 2D spectra have been assigned on the basis of 2H chemical shifts, isotopic data obtained from isotropic quantitative NAD NMR, and by an interspectral comparison of the anisotropic NAD spectra of four

  3. Chlorophyll a specific Δ14C, δ13C and δ15N values in stream periphyton: implications for aquatic food web studies

    NASA Astrophysics Data System (ADS)

    Ishikawa, N. F.; Yamane, M.; Suga, H.; Ogawa, N. O.; Yokoyama, Y.; Ohkouchi, N.

    2015-07-01

    We determined the isotopic composition of chlorophyll a in periphytic algae attached to a streambed substrate (periphyton). The samples were collected from a stream flowing on limestone bedrock in the Seri River, central Japan. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) and natural radiocarbon abundances (Δ14C) were measured in chlorophyll a (δ13Cchl, δ15Nchl and Δ14Cchl) and bulk (δ13Cbulk, δ15Nbulk and Δ14Cbulk) for periphyton, pure aquatic primary producer (Cladophora sp.) and terrestrial primary producer (Quercus glauca). Periphyton δ13Cbulk and δ13Cchl values did not necessarily correspond to δ13Cbulk for an algal-grazing specialist (Mayfly larva, Epeorus latifolium), suggesting that periphyton δ13C values do not faithfully trace carbon transfer between primary producers and primary consumers. Periphyton Δ14Cchl values (-258 ‰ in April and -190 ‰ in October) were slightly lower than Δ14Cbulk values (-228 ‰ in April and -179 ‰ in October), but were close to the Δ14C value for dissolved inorganic carbon (DIC) (-217 ± 31 ‰), which is a mixture of weathered carbonates (Δ14C = -1000 ‰) and dissolved atmospheric CO2 (Δ14C approximately +30 ‰ in 2013). Δ14Cchl values were also close to Δ14Cbulk for E. latifolium (-215 ‰ in April and -199 ‰ in October) and Cladophora sp. (-210 ‰), whereas the Δ14Cbulk value for Q. glauca (+27 ‰) was closer to Δ14C for atmospheric CO2. Although the bulk isotopic composition of periphyton is recognised as a surrogate for the photosynthetic algal community, natural periphyton is a mixture of aquatic and terrestrial organic materials. Our results indicate that the bulk periphyton matrix at the study site consists of 89 to 95 % algal carbon (derived from 14C-depleted DIC) and 5 to 11 % terrestrial organic carbon (derived from 14C-enriched atmospheric CO2).

  4. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  5. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  6. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  7. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  8. 40 CFR 721.6505 - Polymers of C13C15 oxoalcohol ethoxolates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Polymers of C13C15 oxoalcohol... Specific Chemical Substances § 721.6505 Polymers of C13C15 oxoalcohol ethoxolates. (a) Chemical substance... polymers of C13C15 oxoalcohol ethoxolates (PMNs P-96-950/951) are subject to reporting under this...

  9. Prominent bacterial heterotrophy and sources of 13C-depleted fatty acids to the interior Canada Basin

    NASA Astrophysics Data System (ADS)

    Shah, S. R.; Griffith, D. R.; Galy, V.; McNichol, A. P.; Eglinton, T. I.

    2013-11-01

    In recent decades, the Canada Basin of the Arctic Ocean has experienced rapidly decreasing summer sea ice coverage and freshening of surface waters. It is unclear how these changes translate to deeper waters, particularly as our baseline understanding of organic carbon cycling in the deep basin is quite limited. In this study, we describe full-depth profiles of the abundance, distribution and carbon isotopic composition of fatty acids from suspended particulate matter at a seasonally ice-free station and a semi-permanently ice-covered station. Fatty acids, along with suspended particulate organic carbon (POC), are more concentrated and 13C-enriched under ice cover than in ice-free waters. But this influence, apparent at 50 m depth, does not propagate downward below 150 m depth, likely due to the weak biological pump in the central Canada Basin. Branched fatty acids have δ13C values that are similar to suspended POC at all depths and are more 13C-enriched than even-numbered saturated fatty acids at depths above 3000 m. These are likely to be produced in situ by heterotrophic bacteria incorporating organic carbon that is isotopically similar to total suspended POC. Below surface waters, there is also the suggestion of a source of saturated even-numbered fatty acids which could represent contributions from laterally advected organic carbon and/or from chemoautotrophic bacteria. At 3000 m depth and below, a greater relative abundance of long-chain (C20-24), branched and unsaturated fatty acids is consistent with a stronger influence of re-suspended sedimentary organic carbon. At these deep depths, two individual fatty acids (C12 and iso-C17) are significantly depleted in 13C, allowing for the possibility that methane oxidizing bacteria contribute fatty acids, either directly to suspended particulate matter or to shallow sediments that are subsequently mobilized and incorporated into suspended particulate matter within the deep basin.

  10. Accurate measurements of {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    SciTech Connect

    Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Nielsen, Niels Chr.; Khaneja, Navin

    2014-09-21

    Application of sets of {sup 13}C-{sup 13}C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl ({sup 13}C′) and aliphatic ({sup 13}C{sub aliphatic}) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly {sup 13}C,{sup 15}N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of {sup 13}C′-{sup 13}C{sub aliphatic} distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform {sup 13}C,{sup 15}N-labeling on the FGAIL fragment.

  11. Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C-NMR spectroscopy (SIE-DOSY 13C-NMR)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable Isotope-Enhanced Diffusion Ordered (SIE-DOSY) 13C-NMR has been applied to 13C-enriched carbohydrates and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, a disaccharide and a trisaccharide. These 2D spectra were obtained with as little as 8 min of acq...

  12. High-precision position-specific isotope analysis of 13C/12C in leucine and methionine analogues.

    PubMed

    Sacks, Gavin L; Brenna, J Thomas

    2003-10-15

    We report an automated method for high-precision position-specific isotope analysis (PSIA) of carbon in amino acid analogues. Carbon isotope ratios are measured for gas-phase pyrolysis fragments from multiple sources of 3-methylthiopropylamine (3MTP) and isoamylamine (IAA), the decarboxylated analogues of methionine and leucine, using a home-built gas chromatography (GC)-pyrolysis-GC preparation system coupled to a combustion-isotope ratio mass spectrometry system. Over a temperature range of 620-900 degrees C, the characteristic pyrolysis products for 3MTP were CH4, C2H6, HCN, and CH3CN and for IAA products were propylene, isobutylene, HCN, and CH3CN. Fragment origin was confirmed by 13C-labeling, and fragments used for isotope analysis were generated from unique moieties with > 95% structural fidelity. Isotope ratios for the fragments were determined with an average precision of SD(delta13C) < 0.3% per thousand, and relative isotope ratios of fragments from different sources were determined with an average precision of SD(delta(delta)13C) < 0.5% per thousand. Delta(delta)13C values of fragments were invariant over a range of pyrolysis temperatures. The delta(delta)13C of complementary fragments in IAA was within 0.8% per thousand of the delta(delta)13C of the parent compounds, indicating that pyrolysis-induced isotopic fractionation is effectively taken into account with this calibration procedure. Using delta(delta)13C values of fragments, delta(delta)13C values were determined for all four carbon positions of 3MTP and for C1, C2, and the propyl moiety of IAA, either directly or indirectly by mass balance. Large variations in position-specific isotope ratios were observed in samples from different commercial sources. Most dramatically, two 3MTP sources differed by 16.30% per thousand at C1, 48.33% per thousand at C2, 0.37% per thousand at C3, and 5.36% per thousand at C(methyl). These PSIA techniques are suitable for studying subtle changes in intramolecular

  13. Determination of fructose metabolic pathways in normal and fructose-intolerant children: A sup 13 C NMR study using (U- sup 13 C)fructose

    SciTech Connect

    Gopher, A.; Lapidot, A. ); Vaisman, N. ); Mandel, H. )

    1990-07-01

    An inborn deficiency in the ability of aldolase B to split fructose 1-phosphate is found in humans with hereditary fructose intolerance (HFI). A stable isotope procedure to elucidate the mechanism of conversion of fructose to glucose in normal children and in HFI children has been developed. A constant infusion of D-(U-{sup 13}C)fructose was given nasogastrically to control and to HFI children. Hepatic fructose conversion to glucose was estimated by examination of {sup 13}C NMR spectra of plasma glucose. Significantly lower values ({approx}3-fold) for fructose conversion to glucose were obtained for the HFI patients as compared to the controls. A quantitative determination of the metabolic pathways of fructose conversion to glucose was derived from {sup 13}C NMR measurement of plasma ({sup 13}C)glucose isotopomer populations. The finding of isotopomer populations of three adjacent {sup 13}C atoms at glucose C-4 ({sup 13}C{sub 3}-{sup 13}C{sub 4}-{sup 13}C{sub 5}) suggests that there is a direct pathway from fructose, by-passing fructose-1-phosphate aldolase, to fructose 1,6-bisphosphate. The metabolism of fructose by fructose-1-phosphate aldolase activity accounts for only {approx}50% of the total amount of hepatic fructose conversion to glucose. In view of the marked decline by 67% in synthesis of glucose from fructose in HFI subjects found in this study, the extent of ({sup 13}C)glucose formation from a trace amount of (U-{sup 13}C)fructose infused into the patient can be used as a safe and noninvasive diagnostic test for inherent faulty fructose metabolism.

  14. Topological Constraints on Chain-Folding Structure of Semicrystalline Polymer as Studied by 13C-13C Double Quantum NMR

    NASA Astrophysics Data System (ADS)

    Hong, Youlee; Miyoshi, Toshikazu

    Chain-folding process is a prominent feature of long polymer chains during crystallization. Over the last half century, much effort has been paid to reveal the chain trajectory. Even though various chain-folding models as well as theories of crystallization at molecule levels have been proposed, they could be not reconciled due to the limited experimental evidences. Recent development of double quantum NMR with selective isotope labeling identified the chain-trajectory of 13C labeled isotactic poly(1-butene). The systematic experiments covered a wide range of parameters, i.e. kinetics, concentration, and molecular weight (Mw) . It was demonstrated that i) adjacent re-entry site was invariant as a function of crystallization temperature (Tc) , concentration, andMw, ii) long-range order of adjacent re-entry sequence is independence of kinetics at a given concentration while it decreased with increasing the polymer concentration at a given Tc due to the increased interruption between the chains, and iii) high Mw chains led to the multilayer folded structures in single crystals, but the melt state induced the identical short adjacent sequences of long and short polymer over a wide range of Tc due to the entanglements. The behaviors indicated that the topological restriction plays significant roles in the chain-folding process rather than the kinetics. The proposed framework to control the chain-folding structure presents a new perspective into the chain organization by either the intra- or inter-chain interaction. National Science Foundation Grants DMR-1105829 and 1408855.

  15. Utilization of shallow-water seagrass detritus by Carribbean deep-sea macrofauna: δ 13C evidence

    NASA Astrophysics Data System (ADS)

    Suchanek, Thomas H.; Williams, Susan L.; Ogden, John C.; Hubbard, Dennis K.; Gill, Ivan P.

    1985-02-01

    Three dives were made using the DSRV Alvin in the deep-sea basin north of St. Croix, Virgin Islands. Detrital seagrasses and macrofaunal distributions at 2455 to 3950 m depth were assessed quantitatively. Counts of the manatee grass Syringodium filiforme ( ca. 5 to 100 blades m -2) contrasted sharply with those of the turtle grass Thalassia testudinum ( ca. 0.1 to 2.0 blades m -2), reflecting an abundance proportional to previously reported export rates of the same species from Tague Bay, a nearby shallow source lagoon. Of the macrofaunal consumers that could potentially utilize this detrital nutrient source, three species of holothurians ( Mesothuria verrilli, Psychropotes semperiana, and Benthodytes linqua) and two species of sea urchins ( Hygrosoma petersi and Salencidaris profundi) were collected and/or observed. Gut content analyses revealed that all three holothurians deposit-feed on sediment and at least one species of sea urchin ( H. petersi) feeds almost exclusively on Syringodium. Carbon: nitrogen analyses of naturally occurring abyssal Thalassia detritus showed very low nitrogen content (0.21% N) and a high C:N ratio (214.8), thus yielding a loo nutritional value. Fresh Thalassia blades held in a litter bag experiment (by R. D. Turner) at 3950 m changed little in nitrogen content and C:N ratio after four years. A comparison was made of the stable carbon isotope ratios of 13C: 12C for abyssal seagrass detritus and other potential carbon sources with those for tissues from the holothurian and urchin consumers. The results indicate that a significant proportion of the nutrition of both groups is derived from detrital seagrasses either by direct consumption (sea urchins) or indirectly by deposit-feeding on sediments enriched by decomposed seagrasses (holothurians).

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Sc3CH@C80: selective 13C enrichment of the central carbon atom†

    PubMed Central

    Junghans, Katrin; Rosenkranz, Marco; Popov, Alexey A.

    2016-01-01

    Sc3CH@C80 is synthesized and characterized by 1H, 13C, and 45Sc NMR. A large negative chemical shift of the proton, −11.73 ppm in the Ih and −8.79 ppm in the D5h C80 cage isomers, is found. 13C satellites in the 1H NMR spectrum enabled indirect determination of the 13C chemical shift for the central carbon at 173 ± 1 ppm. Intensity of the satellites allowed determination of the 13C content for the central carbon atom. This unique possibility is applied to analyze the cluster/cage 13C distribution in mechanistic studies employing either 13CH4 or 13C powder to enrich Sc3CH@C80 with 13C. PMID:27109443

  18. Sc3CH@C80: selective (13)C enrichment of the central carbon atom.

    PubMed

    Junghans, Katrin; Rosenkranz, Marco; Popov, Alexey A

    2016-05-01

    Sc3CH@C80 is synthesized and characterized by (1)H, (13)C, and (45)Sc NMR. A large negative chemical shift of the proton, -11.73 ppm in the Ih and -8.79 ppm in the D5h C80 cage isomers, is found. (13)C satellites in the (1)H NMR spectrum enabled indirect determination of the (13)C chemical shift for the central carbon at 173 ± 1 ppm. Intensity of the satellites allowed determination of the (13)C content for the central carbon atom. This unique possibility is applied to analyze the cluster/cage (13)C distribution in mechanistic studies employing either (13)CH4 or (13)C powder to enrich Sc3CH@C80 with (13)C. PMID:27109443

  19. Conformational changes of alamethicin induced by solvent and temperature. A 13C-NMR and circular-dichroism study.

    PubMed

    Jung, G; Dubischar, N

    1975-06-01

    13C nuclear magnetic resonance (NMR) and circular dichroism (CD) have been used for studies on the conformation of alamethicin. The 13C NMR spectrum is assigned with the aid of signals of synthetic partial sequences and selective proton decoupling. The solvent and temperature-dependence of the 13C NMR spectra, T1 measurements and the use of lanthanide-shift reagents allow the differentiation between the amino acids belonging to a rigid alpha-helical portion of the alamethicin sequence and those belonging to a more flexible part. The 13C NMR results are in agreement with results obtained from extended solvent and temperature-dependent CD studies which indicate a highly stabilized nonpolar and intrachenar alpha-helical part. The concentration-dependence of the CD spectrum of alamethicin in a nematic phase revealed aggregation phenomena which might simulate those observed in natural and synthetic membranes. After dissolving alamethicin in aqueous alcohol there is a time-dependence of the ellipticity of the Cotton effects showing a sort of memory effect on the mode of dissolution. Four different conformations can be characterized by CD spectra depending on the solvent and concentration. A model illustrating the dynamic conformations and aggregation phenomena within a membrane is proposed. PMID:1175592

  20. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure.

    PubMed

    Lovely, Christina M; O'Connor, Nancy J; Judge, Michael L

    2015-01-01

    Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m(2) with 62 mm(2) mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width) whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1-15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m(-2) [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m(-2)). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations. PMID:26401456

  1. Abundance of non-native crabs in intertidal habitats of New England with natural and artificial structure

    PubMed Central

    Lovely, Christina M.; Judge, Michael L.

    2015-01-01

    Marine habitats containing complex physical structure (e.g., crevices) can provide shelter from predation for benthic invertebrates. To examine effects of natural and artificial structure on the abundance of intertidal juvenile crabs, 2 experiments were conducted in Kingston Bay, Massachusetts, USA, from July to September, 2012. In the first experiment, structure was manipulated in a two-factor design that was placed in the high intertidal for 3 one-week periods to test for both substrate type (sand vs. rock) and the presence or absence of artificial structure (mesh grow-out bags used in aquaculture, ∼0.5 m2 with 62 mm2 mesh openings). The Asian shore crab, Hemigrapsus sanguineus, and small individuals of the green crab, Carcinus maenas, were observed only in the treatments of rocks and mesh bag plus rocks. Most green crabs were small (<6 mm in carapace width) whereas H. sanguineus occurred in a wide range of sizes. In the second experiment, 3 levels of oyster-shell treatments were established using grow-out bags placed on a muddy sand substrate in the low intertidal zone: mesh grow-out bags without shells, grow-out bags with oyster shells, and grow-out bags containing live oysters. Replicate bags were deployed weekly for 7 weeks in a randomized complete block design. All crabs collected in the bags were juvenile C. maenas (1–15 mm carapace width), and numbers of crabs differed 6-fold among treatments, with most crabs present in bags with live oysters (29.5 ± 10.6 m−2 [mean ± S.D.]) and fewest in bags without shells (4.9 ± 3.7 m−2). Both C. maenas and H. sanguineus occurred in habitats with natural structure (cobble rocks). The attraction of juvenile C. maenas to artificial structure consisting of plastic mesh bags containing both oyster shells and living oysters could potentially impact oyster aquaculture operations. PMID:26401456

  2. Natural Abundance 43Ca NMR as a Tool for Exploring Calcium Biomineralization: Renal Stone Formation and Growth

    SciTech Connect

    Bowers, Geoffrey M.; Kirkpatrick, Robert J.

    2011-12-07

    Renal stone diseases are a global health issue with little effective therapeutic recourse aside from surgery and shock-wave lithotripsy, primarily because the fundamental chemical mechanisms behind calcium biomineralization are poorly understood. In this work, we show that natural abundance 43Ca NMR at 21.1 T is an effective means to probe the molecular-level Ca2+ structure in oxalate-based kidney stones. We find that the 43Ca NMR resonance of an authentic oxalate-based kidney stone cannot be explained by a single pure phase of any common Ca2+-bearing stone mineral. Combined with XRD results, our findings suggest an altered calcium oxalate monohydrate-like Ca2+ coordination environment for some fraction of Ca2+ in our sample. The evidence is consistent with existing literature hypothesizing that nonoxalate organic material interacts directly with Ca2+ at stone surfaces and is the primary driver of renal stone aggregation and growth. Our findings show that 43Ca NMR spectroscopy may provide unique and crucial insight into the fundamental chemistry of kidney stone formation, growth, and the role organic molecules play in these processes.

  3. Molecular characterization of dissolved organic matter in glacial ice: coupling natural abundance 1H NMR and fluorescence spectroscopy.

    PubMed

    Pautler, Brent G; Woods, Gwen C; Dubnick, Ashley; Simpson, André J; Sharp, Martin J; Fitzsimons, Sean J; Simpson, Myrna J

    2012-04-01

    Glaciers and ice sheets are the second largest freshwater reservoir in the global hydrologic cycle, and the onset of global climate warming has necessitated an assessment of their contributions to sea-level rise and the potential release of nutrients to nearby aquatic environments. In particular, the release of dissolved organic matter (DOM) from glacier melt could stimulate microbial activity in both glacial ecosystems and adjacent watersheds, but this would largely depend on the composition of the material released. Using fluorescence and (1)H NMR spectroscopy, we characterize DOM at its natural abundance in unaltered samples from a number of glaciers that differ in geographic location, thermal regime, and sample depth. Parallel factor analysis (PARAFAC) modeling of DOM fluorophores identifies components in the ice that are predominantly proteinaceous in character, while (1)H NMR spectroscopy reveals a mixture of small molecules that likely originate from native microbes. Spectrofluorescence also reveals a terrestrial contribution that was below the detection limits of NMR; however, (1)H nuclei from levoglucosan was identified in Arctic glacier ice samples. This study suggests that the bulk of the DOM from these glaciers is a mixture of biologically labile molecules derived from microbes. PMID:22385100

  4. Studies of minute quantities of natural abundance molecules using 2D heteronuclear correlation spectroscopy under 100kHz MAS

    SciTech Connect

    Nishiyama, Y.; Kobayashi, T.; Malon, M.; Singappuli-Arachchige, D.; Slowing, I. I.; Pruski, M.

    2015-02-16

    Two-dimensional 1H{13C} heteronuclear correlation solid-state NMR spectra of naturally abundant solid materials are presented, acquired using the 0.75-mm magic angle spinning (MAS) probe at spinning rates up to 100 kHz. In spite of the miniscule sample volume (290 nL), high-quality HSQC-type spectra of bulk samples as well as surface-bound molecules can be obtained within hours of experimental time. The experiments are compared with those carried out at 40 kHz MAS using a 1.6-mm probe, which offered higher overall sensitivity due to a larger rotor volume. The benefits of ultrafast MAS in such experiments include superior resolution in 1H dimension without resorting to 1H–1H homonuclear RF decoupling, easy optimization, and applicability to mass-limited samples. As a result, the HMQC spectra of surface-bound species can be also acquired under 100 kHz MAS, although the dephasing of transverse magnetization has significant effect on the efficiency transfer under MAS alone.

  5. Adult-onset hypothyroidism and the cerebral metabolism of (1,2-13C2) acetate as detected by 13C nuclear magnetic resonance.

    PubMed

    Chapa, F; Künnecke, B; Calvo, R; Escobar del Rey, F; Morreale de Escobar, G; Cerdán, S

    1995-01-01

    The effects of adult-onset hypothyroidism on the metabolic compartmentation of the cerebral tricarboxylic acid cycle and the gamma-aminobutyric acid (GABA) shunt have been investigated by 13C nuclear magnetic resonance spectroscopy. Rats thyroidectomized as adults and age-matched controls were infused in the right jugular vein with unlabeled or (1,2-13C2) acetate solutions for 60 min. At the end of the infusion, the brains were frozen in situ and perchloric acid extracts were prepared and analyzed by 13C nuclear magnetic resonance and reverse-phase HPLC. Thyroidectomized animals showed a decrease in the incorporation of 13C from (1,2-13C2) acetate in cerebral metabolites and an increase in the concentrations of unlabeled glutamate and GABA. Computer-assisted interpretation of the 13C multiplets observed for the carbons of glutamate, glutamine, and GABA indicated that adult-onset hypothyroidism produced 1) a decrease in the contribution of infused (1,2-13C2) acetate to the glial tricarboxylic acid cycle; 2) an increase in the contribution of unlabeled acetyl-CoA to the neuronal tricarboxylic acid cycle; and 3) impairments in the exchange of glutamate, glutamine, and GABA between the neuronal and glial compartments. Despite the fact that the adult brain has often been considered metabolically unresponsive to thyroid hormone status, present results show metabolic alterations in the neuronal and glial compartments that are reversible with substitution therapy. PMID:7828544

  6. Improved mass analysis of oligoribonucleotides by 13C, 15N double depletion and electrospray ionization FT-ICR mass spectrometry.

    PubMed

    Xiong, Ying; Schroeder, Kersten; Greenbaum, Nancy L; Hendrickson, Christopher L; Marshall, Alan G

    2004-03-15

    13C, 15N doubly depleted 32-ribonucleotide was synthesized enzymatically by in vitro transcription from nucleoside triphosphates isolated from E. coli grown in a minimal medium containing 12C, 14N-enriched glucose and ammonium sulfate. Following purification and desalting by reversed-phase HPLC, buffer exchange with Microcon YM-3, and ethanol precipitation, electrospray ionization Fourier transform ion cyclotron resonance mass spectra revealed greatly enhanced abundance of monoisotopic ions (by a factor of approximately 100) and a narrower isotopic distribution with higher signal-to-noise ratio. The abrupt onset and high magnitude of the monoisotopic species promise to facilitate accurate mass measurement of RNA's. PMID:15018587

  7. Stabilization dynamics of root versus needle-derived 13C and 15N during 10 years in a temperate forest soil.

    NASA Astrophysics Data System (ADS)

    Bird, J. A.; Hatton, P. J.; Castanha, C.; Torn, M. S.

    2012-12-01

    Belowground plant carbon (C) allocation as fine roots can result in greater retention of C in soils compared with aboveground litter in temperate forest ecosystems. However, much of our understanding of the fate of fine root C and nitrogen (N) in soils comes from short-term studies, often lasting only a few months to a few years. In 2011, we concluded a 10-year field study that compared the fate of dual-labeled (13C/15N) Ponderosa pine fine roots (<2 mm diameter) with needles in a temperate forest soil of the Sierra Nevada, CA, USA. The 13C- and 15N-labeled fine roots or needles were added to mesocosms at two soil depths (top of O or A horizon) to compare C and N stabilization in mineral versus organic soil horizons. We will present data on retention of litter C and N in soil after 0.5, 1.5, 5 and 10 years in situ. For soil samples recovered after 5 years, litter-derived C and N recovered in the mineral soil was partitioned into several operationally-defined physical and chemical soil organic matter (SOM) fractions, which were also characterized by natural abundance 14C. In addition, we compared two fractionation methods (i.e., with and without occluded light fraction isolation) on the partitioning of litter-derived C and N in mineral soil. After 5 years in situ the retention of fine root C in soil (59.9±3.8%) was significantly greater than that of added needle C (38.4±2.0%); however the depth of litter placement in the soil did not affect total litter C or N recovery. Our results provide a direct, decade-scale measure of stabilization of above- and belowground plant inputs to soil, including a portrait of the dominant stabilization mechanisms.

  8. Time series of 12CO and 13CO at northern mid-latitudes: determination of partial column and δ13C seasonal and interannual variations

    NASA Astrophysics Data System (ADS)

    Mahieu, E.; Duchatelet, P.; Rinsland, C. P.; Li, Q.; Boone, C. D.; Walker, K. A.; Bernath, P. F.; de Mazière, M.; Dils, B.

    2009-04-01

    Carbon monoxide (CO) is an important reactive gas in the troposphere. It is emitted at the ground level by fossil fuel combustion and biomass burning. Biogenic sources and oceans as well as oxidation of methane and nonmethane hydrocarbons complete the emissions budget. Large uncertainties still affect the relative contributions of the identified anthropogenic and natural sources. Destruction by the hydroxyl radical (OH) is the main removal process for CO in both the troposphere and the stratosphere. The resulting average tropospheric lifetime of CO varies from several weeks to a few months. Two approaches have been developed and optimized to independently retrieve abundances of 12CO and 13CO from high-resolution ground-based infrared solar spectra, using sets of carefully selected lines and the SFIT-2 (v3.91) algorithm which implements the optimal estimation method. The corresponding products will be described and characterized in terms of error budget and information content. These strategies have allowed us to produce partial column time series of 12CO and 13CO, using spectra recorded on a regular basis at the Jungfraujoch station (46.5°N, 8.0°E, 3580 m asl, Swiss Alps), a site of the Network for the Detection of Atmospheric Composition Change (NDACC). The seasonal and interannual changes observed in the12CO,13CO and δ13C (13C/12C) data sets will be presented and discussed. Complementary zonal mean time series derived from occultation measurements collected by the ACE-FTS instrument onboard the Canadian SCISAT-1 platform since 2004 will also be included and analyzed, focusing on the upper troposphere-lower stratosphere region of the atmosphere. Finally, we will use GEOS-Chem 3-D chemistry transport model results to help in the interpretation of the short- and long-term variations characterizing the ground-based and satellite data sets, focusing on the factors influencing the partitioning between the two CO isotopologues.

  9. 12C/ 13C kinetic isotope effects of the gas-phase reactions of isoprene, methacrolein, and methyl vinyl ketone with OH radicals

    NASA Astrophysics Data System (ADS)

    Iannone, Richard; Koppmann, Ralf; Rudolph, Jochen

    The stable-carbon kinetic isotope effects (KIEs) for the gas-phase reactions of isoprene, methacrolein (MACR), and methyl vinyl ketone (MVK) with OH radicals were studied in a 25 L reaction chamber at (298 ± 2) K and ambient pressure. The time dependence of both the stable-carbon isotope ratios and the concentrations was determined using a gas-chromatography combustion isotope ratio mass spectrometry (GCC-IRMS) system. The volatile organic compounds (VOCs) used in the KIE experiments had natural-abundance isotopic composition thus KIE data obtained from these experiments can be directly applied to atmospheric studies of isoprene chemistry. All 12C/ 13/C KIE values are reported as ɛ values, where ɛ = (KIE - 1) × 1000‰, and KIE = k12/ k13. The following average stable-carbon KIEs were obtained: (6.56 ± 0.12)‰ (isoprene), (6.47 ± 0.27)‰ (MACR), and (7.58 ± 0.47)‰ (MVK). The measured KIEs all agree within uncertainty to an inverse molecular mass (MM) dependence of OHɛ(‰) = (487 ± 18)MM -1, which was derived from two previous studies [ J. Geophys. Res.2000, 105, 29329-29346; J. Phys. Chem. A2004, 108, 11537-11544]. Upon adding the isoprene, MACR, and MVK OHɛ values from this study, the inverse MM dependence changes only marginally to OHɛ(‰) = (485 ± 14)MM -1. The addition of these isoprene OHɛ values to a recently measured set of ɛO3 values in an analogous study [ Atmos. Environ.2008, 42, 8728-8737] allows for estimates of the average change in the 12C/ 13C ratio due to processing in the troposphere.

  10. 13C nuclear magnetic resonance study of five- and six-coordinated carbon in nonclassical organometallic compounds: Dimeric trialkyl-, tricyclopropyl-, and triarylaluminums and some nido and closo carboranes*

    PubMed Central

    Olah, George A.; Prakash, G. K. Surya; Liang, Gao; Henold, Kenneth L.; Haigh, Gary B.

    1977-01-01

    A 13C nuclear magnetic resonance spectroscopic study of dimeric trimethyl-, triethyl-, tricyclopropyl-, and triarylaluminums is reported. The five-coordinated bridging carbons are found consistently more shielded than the terminal carbons, in accordance with the increased p-character of the former. The nature of bridging two-electron three-centered Al—C—Al bonds is discussed. 13C nuclear magnetic resonance shifts of several nido and closo carboranes containing five and six coordinated carbons and their 13C-1H spin-spin coupling constants were also obtained. The relationship between the carbon chemical shifts and coordination number of the carbon atom is discussed. There is approximately a 20- to 40-ppm shielding of the 13C chemical shifts of five- and six-coordinated carbons, compared with those of four valent carbons, with a simultaneous general increase of JC-H coupling constants. PMID:16592469

  11. Analysis of hyperpolarized dynamic 13C lactate imaging in a transgenic mouse model of prostate cancer☆

    PubMed Central

    Lupo, Janine M.; Chen, Albert P.; Zierhut, Matthew L.; Bok, Robert A.; Cunningham, Charles H.; Kurhanewicz, John; Vigneron, Daniel B.; Nelson, Sarah J.

    2011-01-01

    This study investigated the application of an acquisition that selectively excites the [1-13C]lactate resonance and allows dynamic tracking of the conversion of 13C-lactate from hyperpolarized 13C-pyruvate at a high spatial resolution. In order to characterize metabolic processes occurring in a mouse model of prostate cancer, 20 sequential 3D images of 13C-lactate were acquired 5 s apart using a pulse sequence that incorporated a spectral–spatial excitation pulse and a flyback echo-planar readout to track the time course of newly converted 13C-lactate after injection of prepolarized 13C-pyruvate. The maximum lactate signal (MLS), full-width half-maximum (FWHM), time to the peak 13C-lactate signal (TTP) and area under the dynamic curve were calculated from the dynamic images of 10 TRAMP mice and two wild-type controls. The regional variation in 13C-lactate associated with the injected pyruvate was demonstrated by the peak of the 13C-lactate signal occurring earlier in the kidney than in the tumor region. The intensity of the dynamic 13C-lactate curves also varied spatially within the tumor, illustrating the heterogeneity in metabolism that was most prominent in more advanced stages of disease development. The MLS was significantly higher in TRAMP mice that had advanced disease. PMID:19695815

  12. Quinone-based stable isotope probing for assessment of 13C substrate-utilizing bacteria

    NASA Astrophysics Data System (ADS)

    Kunihiro, Tadao; Katayama, Arata; Demachi, Toyoko; Veuger, Bart; Boschker, Henricus T. S.; van Oevelen, Dick

    2015-04-01

    13C abundance in the quinone. In this study, we verified carbon stable isotope of quinone compared with bulk carbon stable isotope of bacterial culture. Results indicated a good correlation between carbon stable isotope of quinone compared with bulk carbon stable isotope. However, our measurement conditions for detection of quinone isotope-ions incurred underestimation of 13C abundance in the quinone. The quinone-SIP technique needs further optimization for measurement conditions of LC-MS/MS.

  13. Improved Carbohydrate Structure Generalization Scheme for (1)H and (13)C NMR Simulations.

    PubMed

    Kapaev, Roman R; Toukach, Philip V

    2015-07-21

    The improved Carbohydrate Structure Generalization Scheme has been developed for the simulation of (13)C and (1)H NMR spectra of oligo- and polysaccharides and their derivatives, including those containing noncarbohydrate constituents found in natural glycans. Besides adding the (1)H NMR calculations, we improved the accuracy and performance of prediction and optimized the mathematical model of the precision estimation. This new approach outperformed other methods of chemical shift simulation, including database-driven, neural net-based, and purely empirical methods and quantum-mechanical calculations at high theory levels. It can process structures with rarely occurring and noncarbohydrate constituents unsupported by the other methods. The algorithm is transparent to users and allows tracking used reference NMR data to original publications. It was implemented in the Glycan-Optimized Dual Empirical Spectrum Simulation (GODESS) web service, which is freely available at the platform of the Carbohydrate Structure Database (CSDB) project ( http://csdb.glycoscience.ru). PMID:26087011

  14. High-resolution (13)C nuclear magnetic resonance spectroscopy pattern recognition of fish oil capsules.

    PubMed

    Aursand, Marit; Standal, Inger B; Axelson, David E

    2007-01-10

    13C NMR (nuclear magnetic resonance) spectroscopy, in conjunction with multivariate analysis of commercial fish oil-related health food products, have been used to provide discrimination concerning the nature, composition, refinement, and/or adulteration or authentication of the products. Supervised (probabilistic neural networks, PNN) and unsupervised (principal component analysis, PCA; Kohonen neural networks; generative topographic mapping, GTM) pattern recognition techniques were used to visualize and classify samples. Simple PCA score plots demonstrated excellent, but not totally unambiguous, class distinctions, whereas Kohonen and GTM visualization provided better results. Quantitative class predictions with accuracies >95% were achieved with PNN analysis. Trout, salmon, and cod oils were completely and correctly classified. Samples reported to be salmon oils and cod liver oils did not cluster with true salmon and cod liver oil samples, indicating mislabeling or adulteration. PMID:17199311

  15. Losses of soil carbon by converting tropical forest to plantations: erosion and decomposition estimated by δ(13) C.

    PubMed

    Guillaume, Thomas; Damris, Muhammad; Kuzyakov, Yakov

    2015-09-01

    Indonesia lost more tropical forest than all of Brazil in 2012, mainly driven by the rubber, oil palm, and timber industries. Nonetheless, the effects of converting forest to oil palm and rubber plantations on soil organic carbon (SOC) stocks remain unclear. We analyzed SOC losses after lowland rainforest conversion to oil palm, intensive rubber, and extensive rubber plantations in Jambi Province on Sumatra Island. The focus was on two processes: (1) erosion and (2) decomposition of soil organic matter. Carbon contents in the Ah horizon under oil palm and rubber plantations were strongly reduced up to 70% and 62%, respectively. The decrease was lower under extensive rubber plantations (41%). On average, converting forest to plantations led to a loss of 10 Mg C ha(-1) after about 15 years of conversion. The C content in the subsoil was similar under the forest and the plantations. We therefore assumed that a shift to higher δ(13) C values in plantation subsoil corresponds to the losses from the upper soil layer by erosion. Erosion was estimated by comparing the δ(13) C profiles in the soils under forest and under plantations. The estimated erosion was the strongest in oil palm (35 ± 8 cm) and rubber (33 ± 10 cm) plantations. The (13) C enrichment of SOC used as a proxy of its turnover indicates a decrease of SOC decomposition rate in the Ah horizon under oil palm plantations after forest conversion. Nonetheless, based on the lack of C input from litter, we expect further losses of SOC in oil palm plantations, which are a less sustainable land use compared to rubber plantations. We conclude that δ(13) C depth profiles may be a powerful tool to disentangle soil erosion and SOC mineralization after the conversion of natural ecosystems conversion to intensive plantations when soils show gradual increase of δ(13) C values with depth. PMID:25707391

  16. Contribution of rice straw carbon to CH4 emission from rice paddies using 13C-enriched rice straw

    NASA Astrophysics Data System (ADS)

    Watanabe, Akira; Yoshida, Mariko; Kimura, Makoto

    1998-04-01

    It is generally recognized that the application of rice straw (RS) increases CH4 emission from rice paddies. To estimate the contribution of RS carbon to CH4 emission, a pot experiment was conducted using 13C-enriched RS. The percentage contributions of RS carbon to CH4 emission throughout the rice growth period were 10±1, 32±3, and 43±3% for the treatments with RS applied at the rates of 2, 4, and 6 g kg-1 soil, respectively. The increase in the rate of application of RS increased CH4 emission derived from both RS carbon and other carbon sources. The percentage contribution of RS carbon to CH4 emission was larger in the earlier period (maximum 96%) when the decomposition rate of RS was larger. After RS decomposition had slowed, CH4 emission derived from RS carbon decreased. However, the δ13C values of CH4 emitted from the pots with 13C-enriched RS applied at rates of 4 and 6 g kg-1 soil were significantly higher than those from the pots with natural RS until the harvesting stage. An increased atom-13C% of roots of rice plants growing in the pots with 6 g kg-1 of 13C-enriched RS at around the maximum tiller number stage and a decrease during the following 2 months suggested that rice plants assimilated RS carbon once and then released a portion of it. This supply of RS carbon from roots may be one of the sources of CH4 in the late period of rice growth.

  17. Assessing in situ mineralization of recalcitrant organic compounds in vadose zone sediments using delta13C and 14C measurements.

    PubMed

    Kirtland, Brian C; Aelion, C Marjorie; Stone, Peter A

    2005-01-01

    Few techniques exist to measure the biodegradation of recalcitrant organic compounds such as chlorinated hydrocarbons (CHC) in situ, yet predictions of biodegradation rates are needed for assessing monitored natural attenuation. Traditional techniques measuring O2, CO2, or chemical concentrations (in situ respiration, metabolite and soil air monitoring) may not be sufficiently sensitive to estimate biodegradation rates for these compounds. This study combined isotopic measurements (14C and delta13C of CO2 and delta13C of CHCs) in conjunction with traditional methods to assess in situ biodegradation of perchloroethylene (PCE) and its metabolites in PCE-contaminated vadose zone sediments. CHC, ethene, ethane, methane, O2, and CO2 concentrations were measured over 56 days using gas chromatography (GC). delta13C of PCE, trichloroethylene (TCE) and cis-1,2-dichloroethylene (DCE), delta13C and 14C of vadose zone CO2 and sediment organic matter, and delta13C, 14C, and deltaD of methane were measured using a GC-isotope ratio mass spectrometer or accelerator mass spectrometer. PCE metabolites accounted for 0.2% to 18% of CHC concentration suggesting limited reductive dechlorination. Metabolites TCE and DCE were significantly enriched in (13)C with respect to PCE indicating metabolite biodegradation. Average delta13C-CO2 in source area wells (-23.5 per thousand) was significantly lower compared to background wells (-18.4 per thousand) indicating CHC mineralization. Calculated CHC mineralization rates were 0.003 to 0.01 mg DCE/kg soil/day based on lower 14C values of CO2 in the contaminated wells (63% to 107% modern carbon (pMC)) relative to the control well (117 pMC). Approximately 74% of the methane was calculated to be derived from in situ CHC biodegradation based on the 14C measurement of methane (29 pMC). 14C-CO2 analyses was a sensitive measurement for quantifying in situ recalcitrant organic compound mineralization in vadose zone sediments for which limited

  18. 13C metabolic flux analysis at a genome-scale.

    PubMed

    Gopalakrishnan, Saratram; Maranas, Costas D

    2015-11-01

    Metabolic models used in 13C metabolic flux analysis generally include a limited number of reactions primarily from central metabolism. They typically omit degradation pathways, complete cofactor balances, and atom transition contributions for reactions outside central metabolism. This study addresses the impact on prediction fidelity of scaling-up mapping models to a genome-scale. The core mapping model employed in this study accounts for (75 reactions and 65 metabolites) primarily from central metabolism. The genome-scale metabolic mapping model (GSMM) (697 reaction and 595 metabolites) is constructed using as a basis the iAF1260 model upon eliminating reactions guaranteed not to carry flux based on growth and fermentation data for a minimal glucose growth medium. Labeling data for 17 amino acid fragments obtained from cells fed with glucose labeled at the second carbon was used to obtain fluxes and ranges. Metabolic fluxes and confidence intervals are estimated, for both core and genome-scale mapping models, by minimizing the sum of square of differences between predicted and experimentally measured labeling patterns using the EMU decomposition algorithm. Overall, we find that both topology and estimated values of the metabolic fluxes remain largely consistent between core and GSM model. Stepping up to a genome-scale mapping model leads to wider flux inference ranges for 20 key reactions present in the core model. The glycolysis flux range doubles due to the possibility of active gluconeogenesis, the TCA flux range expanded by 80% due to the availability of a bypass through arginine consistent with labeling data, and the transhydrogenase reaction flux was essentially unresolved due to the presence of as many as five routes for the inter-conversion of NADPH to NADH afforded by the genome-scale model. By globally accounting for ATP demands in the GSMM model the unused ATP decreased drastically with the lower bound matching the maintenance ATP requirement. A non

  19. HYPERPOLARIZED 13C MAGNETIC RESONANCE AND ITS USE IN METABOLIC ASSESSMENT OF CULTURED CELLS AND PERFUSED ORGANS

    PubMed Central

    Lumata, Lloyd; Yang, Chendong; Ragavan, Mukundan; Carpenter, Nicholas; DeBerardinis, Ralph J.; Merritt, Matthew E.

    2016-01-01

    Diseased tissue is often characterized by abnormalities in intermediary metabolism. Observing these alterations in situ may lead to an improved understanding of pathological processes and novel ways to monitor these processes non-invasively in human patients. Although 13C is a stable isotope safe for use in animal models of disease as well as human subjects, its utility as a metabolic tracer has largely been limited to ex vivo analyses employing analytical techniques like mass spectrometry or nuclear magnetic resonance spectroscopy. Neither of these techniques is suitable for non-invasive metabolic monitoring, and the low abundance and poor gyromagnetic ratio of conventional 13C make it a poor nucleus for imaging. However, the recent advent of hyperpolarization methods, particularly dynamic nuclear polarization (DNP), make it possible to enhance the spin polarization state of 13C by many orders of magnitude, resulting in a temporary amplification of the signal sufficient for monitoring kinetics of enzyme-catalyzed reactions in living tissue through magnetic resonance spectroscopy or magnetic resonance imaging. Here we review DNP techniques to monitor metabolism in cultured cells, perfused hearts, and perfused livers, focusing on our experiences with hyperpolarized [1-13C]pyruvate. We present detailed approaches to optimize the DNP procedure, streamline biological sample preparation, and maximize detection of specific metabolic activities. We also discuss practical aspects in the choice of metabolic substrates for hyperpolarization studies, and outline some of the current technical and conceptual challenges in the field, including efforts to use hyperpolarization to quantify metabolic rates in vivo. PMID:26358902

  20. Survival of free-living Acholeplasma in aerated pig manure slurry revealed by 13C-labeled bacterial biomass probing

    PubMed Central

    Hanajima, Dai; Aoyagi, Tomo; Hori, Tomoyuki

    2015-01-01

    Many studies have been performed on microbial community succession and/or predominant taxa during the composting process; however, the ecophysiological roles of microorganisms are not well understood because microbial community structures are highly diverse and dynamic. Bacteria are the most important contributors to the organic-waste decomposition process, while decayed bacterial cells can serve as readily digested substrates for other microbial populations. In this study, we investigated the active bacterial species responsible for the assimilation of dead bacterial cells and their components in aerated pig manure slurry by using 13C-labeled bacterial biomass probing. After 3 days of forced aeration, 13C-labeled and unlabeled dead Escherichia coli cell suspensions were added to the slurry. The suspensions contained 13C-labeled and unlabeled bacterial cell components, possibly including the cell wall and membrane, as well as intracellular materials. RNA extracted from each slurry sample 2 h after addition of E. coli suspension was density-resolved by isopycnic centrifugation and analyzed by terminal restriction fragment length polymorphism, followed by cloning and sequencing of bacterial 16S rRNA genes. In the heavy isotopically labeled RNA fraction, the predominant 13C-assimilating population was identified as belonging to the genus Acholeplasma, which was not detected in control heavy RNA. Acholeplasma spp. have limited biosynthetic capabilities and possess a wide variety of transporters, resulting in their metabolic dependence on external carbon and energy sources. The prevalence of Acholeplasma spp. was further confirmed in aerated pig manure slurry from four different pig farms by pyrosequencing of 16S rRNA genes; their relative abundance was ∼4.4%. Free-living Acholeplasma spp. had a competitive advantage for utilizing dead bacterial cells and their components more rapidly relative to other microbial populations, thus allowing the survival and prevalence

  1. Soil organic matter stability in agricultural land: New insights using δ15N, δ13C and C:N ratio

    NASA Astrophysics Data System (ADS)

    Mao, Yanling; Heiling, Maria; De Clercq, Tim; Resch, Christian; Aigner, Martina; Mayr, Leo; Vanlauwe, Bernard; Thuita, Moses; Steier, Peter; Leifeld, Jens; Merckx, Roel; Spiegel, Heide; Cepuder, Peter; Nguyen, Minh-Long; Zaman, Mohammad; Dercon, Gerd

    2014-05-01

    Soil organic matter (SOM) contains three times more carbon than in the atmosphere or terrestrial vegetation. This major pool of organic carbon is sensitive to climate change, but the mechanisms for carbon stabilization in soils are still not well understood and the ultimate potential for carbon stabilization is unknown. For predicting SOM dynamics, it is necessary to gain information on the turnover rates or stability of different soil organic carbon pools. The common method to determine stability and age of SOM is the 14C radio carbon technique, which is very expensive and therefore limited in use. Conen et al. (2008) developed a model to estimate the SOM stability based on the isotopic discrimination of 15N natural abundance by soil micro-organisms, and the decreasing C:N ratio during organic matter decomposition. This model has been developed for permanent grasslands in the Swiss Alps under steady-state conditions. The objective of our study was to validate whether this model could be used or adapted, in combination with 13C isotope signatures of SOM, to predict the relative age and stability of SOM fractions in more disturbed agricultural ecosystems. The present study was carried out on soils collected from six long-term experimental trials (from 12 to 50 years) under different agricultural management practices (e.g. no tillage vs conventional tillage, and mulch, fertilizer, green or animal manure application), located in Austria, Belgium, Kenya and China. Top and subsoil were sampled until 80-100 cm depth. Particulate organic matter (POM) fraction was obtained by wet sieving (> 63μm) after sonification and density separation (<1.8 g cm-3). Carbon and nitrogen contents and their stable isotopic ratios (i.e. 15N and 13C) were measured in POM and bulk soils. The mineral associated matter fraction (mOM), as the protected carbon, was calculated by difference to the bulk soil organic carbon. The relative age of the SOM was calculated using the Conen model and

  2. On-site analysis of d13C- and dD-CH4 by laser spectroscopy for the allocation of source processes

    NASA Astrophysics Data System (ADS)

    Eyer, Simon; Tuzson, Béla; Popa, Elena; van der Veen, Carina; Röckmann, Thomas; Brand, Willi A.; Fisher, Rebecca; Lowry, David; Nisbet, Euan G.; Brennwald, Matthias S.; Harris, Eliza; Emmenegger, Lukas; Fischer, Hubertus; Mohn, Joachim

    2015-04-01

    Analysis of the most abundant methane isotopologues 12CH4, 13CH4 and 12CH3D can be used to disentangle source/sink processes (Fischer et al. 2008) and to develop target oriented reduction strategies. Isotopic analysis of CH4 is accomplished by isotope-ratio mass-spectrometry (IRMS) and more recently by mid-infrared laser spectroscopy. For high precision measurements in ambient air, however, both techniques rely on preconcentration of the target gas (Eyer et al. 2014). We developed a field-deployable analyser for real-time, on-site analysis of CH4 isotopologues which is based on a dual quantum cascade laser absorption spectrometer (QCLAS) in combination with an innovative preconcentration technique named trace gas extractor (TREX). The core part of the 19 ″ rack-mounted preconcentration unit is a highly efficient adsorbent trap attached to the cold end of a Stirling cooler. The system achieves preconcentration factors >500. For fast desorption and optimal heat management, the trap is decoupled from the cooler during desorption. The QCLAS has been developed based on a previously described instrument (Tuzson 2010). It comprises two cw-QC laser sources combined and coupled into an astigmatic multipass absorption cell with 76 m optical path. The developed technique reaches an unsurpassed precision of 0.1‰ for d13C-CH4 and <0.5‰ for dD-CH4 at 600 s spectral averaging. The potential of the new analytical system for field applications has been shown in June 2014, where the system has achieved an overall repeatability of 0.19‰ for d13C and 1.7‰ for dD-CH4 for repeated target gas measurements. Compatibility of TREX - QCLAS with flask sampling - IRMS for analysis of ambient CH4 fulfilled the extended WMO/GAW compatibility goals of 0.2‰ for d13C-CH4 and 5‰ for dD-CH4. References: Fischer, H., Behrens, M., Bock, M., Richter, U., Schmitt, J., Loulergue, L., Chappellaz, J., Spahni, R., Blunier, T., Leuenberger, M., Stocker, T. F. (2008) Nature 452: 864-867. Eyer, S

  3. Estimation of biological nitrogen fixation by black locust in short-rotation forests using natural 15N abundance method

    NASA Astrophysics Data System (ADS)

    Veste, M.; Böhm, C.; Quinckenstein, A.; Freese, D.

    2012-04-01

    The importance of short rotation forests and agroforestry systems for woody biomass production for bioenergy will increase in Central Europe within the next decades. In this context, black locust (Robinia pseudoacacia) has a high growth potential especially at marginal, drought-susceptible sites such as occur in Brandenburg State (Eastern Germany). As a pioneer tree species black locust grows under a wide range of site conditions. The native range of black locust in Northern America is classified by a humid to sub-humid climate with a mean annual precipitation of 1020 to 1830 mm. In Central and Eastern Europe, this species is cultivated in a more continental climate with an annual precipitation often below 600 mm. Therefore, black locust is known to be relatively drought tolerant compared to other temperate, deciduous tree species. Because of its N2-fixation ability black locust plays generally an important role for the improvement of soil fertility. This effect is of particular interest at marginal sites in the post-mining landscapes. In order to estimate the N2-fixation potential of black locust at marginal sites leaf samples were taken from black locust trees in short rotation plantations planted between 1995 and 2007 in post-mining sites south of Cottbus (Brandenburg, NE Germany). The variation of the natural 15N abundance was measured to evaluate the biological nitrogen fixation. The nitrogen derived from the atmosphere can be calculated using a two-pool model from the quotient of the natural 15N abundances of the N2-fixing plant and the plant available soil N. Because representatively determining the plant available soil N is difficult, a non-N2-fixing reference plant growing at the same site with a similar root system and temporal N uptake pattern to the N2-fixing plant is often used. In our case we used red oak (Quercus rubra) as a reference. The average nitrogen content in the leaves of black locust ranged from 3.1% (C/N 14.8) in 15 years old trees to 3

  4. Rapid detection and characterization of surface CO2 leakage through the real-time measurement of δ13C signatures in CO2 flux from the ground

    NASA Astrophysics Data System (ADS)

    Krevor, Samuel; Benson, Sally; Rella, Chris; Perrin, Jean-Christophe; Esposito, Ariel; Crosson, Eric

    2010-05-01

    The surface monitoring of CO2 over geologic sequestration sites will be an essential tool in the monitoring and verification of sequestration projects. Surface monitoring is the only tool that currently provides the opportunity to detect and quantify leakages on the order of 1000 tons/year CO2. Near-surface detection and quantification can be made complicated, however, due to large temporal and spatial variations in natural background CO2 fluxes from biological processes. In addition, current surface monitoring technologies, such as the use of IR spectroscopy in eddy covariance towers and aerial surveys, radioactive or noble gas isotopic tracers, and flux chamber gas measurements can generally accomplish one or two of the necessary tasks of leak detection, identification, and quantification, at both large spatial scales and high spatial resolution. It would be useful, however, to combine the utility of these technologies so that a much simplified surface monitoring program can be deployed. Carbon isotopes of CO2 provide an opportunity to distinguish between natural biogenic CO2 fluxes from the ground and CO2 leaking from a sequestration reservoir that has ultimate origins in a process giving it a distinct isotopic signature such as natural gas processing. Until recently, measuring isotopic compositions of gases was a time-consuming and expensive process utilizing mass-spectrometry, not practical for deployment in a high-resolution survey of a potential leakage site at the surface. Recent developments in commercially available instruments utilizing wavelength scanned cavity ringdown spectroscopy (WS-CRDS) and Fourier transform infrared spectroscopy (FT-IR) have made it possible to rapidly measure the isotopic composition of gases including the 13C and 12C isotopic composition of CO2 in a field setting. A portable stable carbon isotope ratio analyzer for carbon dioxide, based on wavelength scanned cavity ringdown spectroscopy, has been used to rapidly detect and

  5. Using natural abundance radiocarbon to trace the flux of petrocarbon to the seafloor following the Deepwater Horizon oil spill.

    PubMed

    Chanton, Jeffrey; Zhao, Tingting; Rosenheim, Brad E; Joye, Samantha; Bosman, Samantha; Brunner, Charlotte; Yeager, Kevin M; Diercks, Arne R; Hollander, David

    2015-01-20

    In 2010, the Deepwater Horizon accident released 4.6–6.0 × 10(11) grams or 4.1 to 4.6 million barrels of fossil petroleum derived carbon (petrocarbon) as oil into the Gulf of Mexico. Natural abundance radiocarbon measurements on surface sediment organic matter in a 2.4 × 10(10) m(2) deep-water region surrounding the spill site indicate the deposition of a fossil-carbon containing layer that included 1.6 to 2.6 × 10(10) grams of oil-derived carbon. This quantity represents between 0.5 to 9.1% of the released petrocarbon, with a best estimate of 3.0–4.9%. These values may be lower limit estimates of the fraction of the oil that was deposited on the seafloor because they focus on a limited mostly deep-water area of the Gulf, include a conservative estimate of thickness of the depositional layer, and use an average background or prespill radiocarbon value for sedimentary organic carbon that produces a conservative value. A similar approach using hopane tracer estimated that 4–31% of 2 million barrels of oil that stayed in the deep sea settled on the bottom. Converting that to a percentage of the total oil that entered into the environment (to which we normalized our estimate) converts this range to 1.8 to 14.4%. Although extrapolated over a larger area, our independent estimate produced similar values. PMID:25494527

  6. Cumulative fission yields of short-lived isotopes under natural-abundance-boron-carbide-moderated neutron spectrum

    SciTech Connect

    Finn, Erin C.; Metz, Lori A.; Greenwood, Lawrence R.; Pierson, Bruce; Wittman, Richard S.; Friese, Judah I.; Kephart, Rosara F.

    2015-04-09

    The availability of gamma spectroscopy data on samples containing mixed fission products at short times after irradiation is limited. Due to this limitation, data interpretation methods for gamma spectra of mixed fission product samples, where the individual fission products have not been chemically isolated from interferences, are not well-developed. The limitation is particularly pronounced for fast pooled neutron spectra because of the lack of available fast reactors in the United States. Samples containing the actinide isotopes 233, 235, 238U, 237Np, and 239Pu individually were subjected to a 2$ pulse in the Washington State University 1 MW TRIGA reactor. To achieve a fission-energy neutron spectrum, the spectrum was tailored using a natural abundance boron carbide capsule to absorb neutrons in the thermal and epithermal region of the spectrum. Our tailored neutron spectrum is unique to the WSU reactor facility, consisting of a soft fission spectrum that contains some measurable flux in the resonance region. This results in a neutron spectrum at greater than 0.1 keV with an average energy of 70 keV, similar to fast reactor spectra and approaching that of 235U fission. Unique fission product gamma spectra were collected from 4 minutes to 1 week after fission using single-crystal high purity germanium detectors. Cumulative fission product yields measured in the current work generally agree with published fast pooled fission product yield values from ENDF/B-VII, though a bias was noted for 239Pu. The present work contributes to the compilation of energy-resolved fission product yield nuclear data for nuclear forensic purposes.

  7. Plant and Soil Natural Abundance delta-15N: Indicators of Nitrogen Cycling in the Catskill Mountains, New York, USA

    NASA Astrophysics Data System (ADS)

    Templer, P. H.; Lovett, G. M.; Weathers, K.; Arthur, M. A.

    2002-12-01

    We examined the potential use of natural abundance 15N of plants and soils as an indicator of forest nitrogen (N) cycling rates within the Catskill Mountains, NY. These watersheds receive among the highest rates of N deposition in the northeastern United States and are beginning to show signs of N saturation. Many studies have shown a link between increased N cycling rates and 15N enrichment of soil and plant pools. Faster rates of N cycling processes, especially nitrification, lead to fractionation of 14/15N, creating N products that are relatively depleted in 15N. This can lead to enrichment of soil pools, as lighter 14N is lost from the system via leaching or denitrification. Plant N pools can become increasingly enriched as they take up 15N-enriched soil N. Despite similar amounts of N deposition across the Catskill Mountains, forests dominated by different tree species appear to vary in the amount of N retained or lost to nearby streams. To determine if plant and soil 15N could be used as indicators of N cycling rates, we collected foliage, wood, litterfall, organic and mineral soil, and fine roots from single species stands of American beech (Fagus grandifolia), eastern hemlock (Tsuga canadensis), red oak (Quercus rubra), and sugar maple (Acer saccharum). Fine roots and soil 15N were highest within sugar maple stands (p<0.05). Sugar maple soils also had the highest rates of net nitrification and N leaching. Therefore, soil 15N appears to correlate with forest N retention and loss. However, 15N enrichment was highest within foliage, litterfall and wood of beech trees (p<0.05). The decoupling between foliage 15N and N cycling, as well as between 15N of foliage and fine roots, illustrates that it may not be possible to use a single plant pool as an indicator of N cycling rates.

  8. Metabolic pathways for ketone body production. /sup 13/C NMR spectroscopy of rat liver in vivo using /sup 13/C-multilabeled fatty acids

    SciTech Connect

    Pahl-Wostl, C.; Seelig, J.

    1986-11-04

    The hormonal regulation of ketogenesis in the liver of living rat has been studied noninvasively with /sup 13/C nuclear magnetic resonance. The spatial selection for the liver was better than 90%, with extrahepatic adipose tissue contribution only a very small amount of signal. The metabolic activities of the liver were investigated by infusion of /sup 13/C-labeled butyrate in the jugular vein of the anesthetized rat. The rate of butyrate infusion was chosen to be close to the maximum oxidative capacity of the rat liver, and the /sup 13/C signal intensities were enhanced by using doubly labeled (1,3-/sup 13/C)butyrate as a substrate. Different /sup 13/C NMR spectra and hence different metabolites were observed depending on the hormonal state of the animal. The /sup 13/C NMR studies demonstrate that even when rate of acetyl-CoA production are high, the disposal of this compound is not identical in fasted and diabetic animals. This supports previous suggestions that the redox state of the mitochondrion represents the most important factor in regulation. For a given metabolic state of the animal, different signal intensities were obtained depending on whether butyrate was labeled at C-1, C-3, or C-1,3. From the ratios of incorporation of /sup 13/C label into the carbons of 3-hydroxybutyrate, it could be estimated that a large fraction of butyrate evaded ..beta..-oxidation to acetyl-CoA but was converted directly to acetoacetyl-CoA. /sup 13/C-labeled glucose could be detected in vivo in the liver of diabetic rats.

  9. FOURIER TRANSFORM EMISSION SPECTROSCOPY OF THE B {sup 2}{Sigma}{sup +}-X {sup 2}{Sigma}{sup +} (VIOLET) SYSTEM OF {sup 13}C{sup 14}N

    SciTech Connect

    Ram, R. S.; Bernath, P. F.

    2011-06-01

    Emission spectra of the B {sup 2}{Sigma}{sup +}-X {sup 2}{Sigma}{sup +} transition of {sup 13}C{sup 14}N have been observed at high resolution using the Fourier transform spectrometer associated with the McMath-Pierce Solar Telescope of the National Solar Observatory. The spectra have been measured in the 21000-30000 cm{sup -1} region and a total of 52 vibrational bands involving vibrational levels up to v = 15 of the ground and excited states have been rotationally analyzed to provide a much improved set of spectroscopic constants. An experimental line list and calculated term values are provided. The results of the present analysis should prove useful in the identification of additional {sup 13}C{sup 14}N lines in comets and cool stars, and will help in the determination of the {sup 12}C/{sup 13}C abundance ratio.

  10. Photosynthesis and sup 13 C/ sup 12 C ratios in Amazonian rain forests

    SciTech Connect

    Van Der Merwe, N.J. ); Medina, E. )

    1989-05-01

    Measurements are reported of {sup 13}C/{sup 12}C ratios for air CO{sub 2} at different heights in two Amazonian rain forests. CO{sub 2} emitted from the forest floor is severely depleted in {sup 13}C which produces isotopically light source air throughout the forest. Air {delta}{sup 13}C values vary very little with height above ground, but are about 5 to 6{per thousand} more negative than the open atmosphere. CO{sub 2} recycling under the canopy depletes all leaf {delta}{sup 13}C values by a like amount. Additional factors further deplete leaf {delta}{sup 13}C values by 4 to 5{per thousand} at ground level; this effect decreases with height to zero in the upper canopy, yielding a gradient in {delta}{sup 13}C values.

  11. Biosynthesis of highly enriched 13C-lycopene for human metabolic studies using repeated batch tomato cell culturing with 13C-glucose

    PubMed Central

    Moran, Nancy E.; Rogers, Randy B.; Lu, Chi-Hua; Conlon, Lauren E.; Lila, Mary Ann; Clinton, Steven K.; Erdman, John W.

    2013-01-01

    While putative disease-preventing lycopene metabolites are found in both tomato (Solanum lycopersicum) products and in their consumers, mammalian lycopene metabolism is poorly understood. Advances in tomato cell culturing techniques offer an economical tool for generation of highly-enriched 13C-lycopene for human bioavailability and metabolism studies. To enhance the 13C-enrichment and yields of labeled lycopene from the hp-1 tomato cell line, cultures were first grown in 13C-glucose media for three serial batches and produced increasing proportions of uniformly labeled lycopene (14.3 +/− 1.2 %, 39.6 +/− 0.5 %, and 48.9 +/− 1.5% with consistent yields (from 5.8 to 9 mg/L). An optimized 9-day-long 13C-loading and 18-day-long labeling strategy developed based on glucose utilization and lycopene yields, yielded 13C-lycopene with 93% 13C isotopic purity, and 55% of isotopomers were uniformly labeled. Furthermore, an optimized acetone and hexane extraction led to a four-fold increase in lycopene recovery from cultures compared to a standard extraction. PMID:23561155

  12. Coupling and higher-order effects in the {sup 12}C(d,p){sup 13}C and {sup 13}C(p,d){sup 12}C reactions

    SciTech Connect

    Delaunay, F.; Nunes, F.M.; Lynch, W.G.; Tsang, M.B.

    2005-07-01

    Coupled-channel calculations are performed for the {sup 12}C(d,p){sup 13}C and {sup 13}C(p,d){sup 12}C reactions between 7 and 60 MeV to study the effect of inelastic couplings in transfer reactions. The effect of treating transfer beyond Born approximation is also addressed. The coupling to the {sup 12}C 2{sup +} state is found to change the peak cross section by up to 15%. Effects beyond Born approximation lead to a significant renormalization of the cross sections, between 5% and 10% for deuteron energies above 10 MeV and larger than 10% for lower energies. We also performed calculations including the remnant term in the transfer operator, which has a small impact on the {sup 12}C(d,p){sup 13}C(g.s.) and {sup 13}C(p,d){sup 12}C(g.s.) reactions (where g.s. indicates ground state). Above 30-MeV deuteron energy, the effect of the remnant term is larger than 10% for the {sup 12}C(d,p){sup 13}C(1/2{sup +}, 3.09 MeV) reaction and is found to increase with decreasing neutron separation energy for the 3.09-MeV state of {sup 13}C. This is of importance for transfer reactions with weakly bound nuclei.

  13. Synthesis of isotopically labeled R- or S-[.sup.13C, .sup.2H] glycerols

    DOEpatents

    Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

    2008-01-22

    The present invention is directed to asymmetric chiral labeled glycerols including at least one chiral atom, from one to two .sup.13C atoms and from zero to four deuterium atoms bonded directly to a carbon atom, e.g., (2S) [1,2-.sup.13C.sub.2]glycerol and (2R) [1,2-.sup.13C.sub.2]glycerol, and to the use of such chiral glycerols in the preparation of labeled amino acids.

  14. A large metabolic carbon contribution to the δ 13C record in marine aragonitic bivalve shells

    NASA Astrophysics Data System (ADS)

    Gillikin, David P.; Lorrain, Anne; Meng, Li; Dehairs, Frank

    2007-06-01

    It is well known that the incorporation of isotopically light metabolic carbon (C M) significantly affects the stable carbon isotope (δ 13C) signal recorded in biogenic carbonates. This can obscure the record of δ 13C of seawater dissolved inorganic carbon (δ 13C DIC) potentially archived in the shell carbonate. To assess the C M contribution to Mercenaria mercenaria shells collected in North Carolina, USA, we sampled seawater δ 13C DIC, tissue, hemolymph and shell δ 13C. All shells showed an ontogenic decrease in shell δ 13C, with as much as a 4‰ decrease over the lifespan of the clam. There was no apparent ontogenic change in food source indicated by soft tissue δ 13C values, therefore a change in the respired δ 13C value cannot be the cause of this decrease. Hemolymph δ 13C, on the other hand, did exhibit a negative relationship with shell height indicating that respired CO 2 does influence the δ 13C value of internal fluids and that the amount of respired CO 2 is related to the size or age of the bivalve. The percent metabolic C incorporated into the shell (%C M) was significantly higher (up to 37%, with a range from 5% to 37%) than has been found in other bivalve shells, which usually contain less than 10%C M. Interestingly, the hemolymph did contain less than 10%C M, suggesting that complex fractionation might occur between hemolymph and calcifying fluids. Simple shell biometrics explained nearly 60% of the observed variability in %C M, however, this is not robust enough to predict %C M for fossil shells. Thus, the metabolic effect on shell δ 13C cannot easily be accounted for to allow reliable δ 13C DIC reconstructions. However, there does seem to be a common effect of size, as all sites had indistinguishable slopes between the %C M and shell height (+0.19% per mm of shell height).

  15. Measuring (13)C-(2)D dipolar couplings with a universal REDOR dephasing curve

    PubMed

    Gullion

    2000-09-01

    A (13)C-observe REDOR experiment is described which allows (13)C-(2)D dipolar couplings to be obtained by a universal dipolar dephasing curve. Previous (13)C-observe REDOR experiments on (13)C-(2)D spin pairs generally relied on numerical simulations to obtain the dipolar coupling. The REDOR experiment described in this article is based on a deuterium composite pulse, and the data analysis eliminates the need for numerical simulations and is the same as the traditional REDOR analysis performed on pairs of spin-12 nuclei. Copyright 2000 Academic Press. PMID:10968975

  16. Open-Source Automated Parahydrogen Hyperpolarizer for Molecular Imaging Using (13)C Metabolic Contrast Agents.

    PubMed

    Coffey, Aaron M; Shchepin, Roman V; Truong, Milton L; Wilkens, Ken; Pham, Wellington; Chekmenev, Eduard Y

    2016-08-16

    An open-source hyperpolarizer producing (13)C hyperpolarized contrast agents using parahydrogen induced polarization (PHIP) for biomedical and other applications is presented. This PHIP hyperpolarizer utilizes an Arduino microcontroller in conjunction with a readily modified graphical user interface written in the open-source processing software environment to completely control the PHIP hyperpolarization process including remotely triggering an NMR spectrometer for efficient production of payloads of hyperpolarized contrast agent and in situ quality assurance of the produced hyperpolarization. Key advantages of this hyperpolarizer include: (i) use of open-source software and hardware seamlessly allowing for replication and further improvement as well as readily customizable integration with other NMR spectrometers or MRI scanners (i.e., this is a multiplatform design), (ii) relatively low cost and robustness, and (iii) in situ detection capability and complete automation. The device performance is demonstrated by production of a dose (∼2-3 mL) of hyperpolarized (13)C-succinate with %P13C ∼ 28% and 30 mM concentration and (13)C-phospholactate at %P13C ∼ 15% and 25 mM concentration in aqueous medium. These contrast agents are used for ultrafast molecular imaging and spectroscopy at 4.7 and 0.0475 T. In particular, the conversion of hyperpolarized (13)C-phospholactate to (13)C-lactate in vivo is used here to demonstrate the feasibility of ultrafast multislice (13)C MRI after tail vein injection of hyperpolarized (13)C-phospholactate in mice. PMID:27478927

  17. Sub-second Proton Imaging of 13C Hyperpolarized Contrast Agents in Water

    PubMed Central

    Truong, Milton L.; Coffey, Aaron M.; Shchepin, Roman V.; Waddell, Kevin W.; Chekmenev, Eduard Y.

    2014-01-01

    Indirect proton detection of 13C hyperpolarized contrast agents potentially enables greater sensitivity. Presented here is a study of sub-second projection imaging of hyperpolarized 13C contrast agent addressing the obstacle posed by water suppression for indirect detection in vivo. Sodium acetate phantoms were used to develop and test water suppression and sub-second imaging with frequency selective RF pulses using spectroscopic and imaging indirect proton detection. A 9.8 mM aqueous solution of 13C PHIP hyperpolarized 2-hydroxyethyl-13C-propionate-d2,3,3 (HEP),

    ~25% was used for demonstration of indirect proton sub-second imaging detection. Balanced 2D FSSFP (Fast Steady State Free Precession) allowed recording proton images with FOV = 64×64 mm2 and spatial resolution 2×2 mm2 with total acquisition time of less than 0.2 s. In thermally polarized sodium 1-13C-acetate, 13C to 1H polarization transfer efficiency of 45.1% of the theoretically predicted values was observed in imaging detection corresponding to an 11 fold of overall sensitivity improvement compared to direct 13C FSSFP imaging. 13C to 1H polarization transfer efficiency of 27% was observed in imaging detection corresponding to a 3.25 fold sensitivity improvement compared to direct 13C FSSFP imaging with hyperpolarized HEP. The range of potential applications and limitations of this sub-second and ultra-sensitive imaging approach are discussed. PMID:24753438

  18. Lack of 13C-label incorporation suggests low turnover rates of thaumarchaeal intact polar tetraether lipids in sediments from the Iceland Shelf

    NASA Astrophysics Data System (ADS)

    Lengger, S. K.; Lipsewers, Y. A.; de Haas, H.; Sinninghe Damsté, J. S.; Schouten, S.

    2013-08-01

    Thaumarchaeota are amongst the most abundant microorganisms in aquatic environments, however, their metabolism in marine sediments is still debated. Labeling studies in marine sediments have previously been undertaken, but focused on complex organic carbon substrates which Thaumarchaeota have not yet been shown to take up. In this study, we investigated the activity of Thaumarchaeota in sediments by supplying different 13C-labeled substrates which have previously been shown to be incorporated into archaeal cells in water incubations and/or enrichment cultures. We determined the incorporation of 13C-label from bicarbonate, pyruvate, glucose and amino acids into thaumarchaeal intact polar lipid-glycerol dibiphytanyl glycerol tetraethers (IPL-GDGTs) during 4-6 day incubations of marine sediment cores from three different sites on the Iceland Shelf. Thaumarchaeal intact polar lipids were detected at all stations and concentrations remained constant or decreased slightly upon incubation. No 13C incorporation in any IPL-GDGT was observed at stations 2 (clay-rich sediment) and 3 (organic-rich sediment). In bacterial/eukaryotic IPL-derived fatty acids at station 3, contrastingly, a large uptake of 13C label (up to +80‰) was found. 13C was also respired during the experiment as shown by a substantial increase in the 13C content of the dissolved inorganic carbon. In IPL-GDGTs recovered from the sandy sediments at station 1, however, some enrichment in 13C (1-4‰) was detected after incubation with bicarbonate and pyruvate. The low incorporation rates suggest a low activity of Thaumarchaeota in marine sediments and/or a low turnover rate of thaumarchaeal IPL-GDGTs due to their low degradation rates. Cell numbers and activity of sedimentary Thaumarchaeota based on IPL-GDGT measurements may thus have previously been overestimated.

  19. Lack of 13C-label incorporation suggests low turnover rates of thaumarchaeal intact polar tetraether lipids in sediments from the Iceland shelf

    NASA Astrophysics Data System (ADS)

    Lengger, S. K.; Lipsewers, Y. A.; de Haas, H.; Sinninghe Damsté, J. S.; Schouten, S.

    2014-01-01

    Thaumarchaeota are amongst the most abundant microorganisms in aquatic environments, however, their metabolism in marine sediments is still debated. Labeling studies in marine sediments have previously been undertaken, but focused on complex organic carbon substrates which Thaumarchaeota have not yet been shown to take up. In this study, we investigated the activity of Thaumarchaeota in sediments by supplying different 13C-labeled substrates which have previously been shown to be incorporated into archaeal cells in water incubations and/or enrichment cultures. We determined the incorporation of 13C-label from bicarbonate, pyruvate, glucose and amino acids into thaumarchaeal intact polar lipid-glycerol dibiphytanyl glycerol tetraethers (IPL-GDGTs) during 4-6 day incubations of marine sediment cores from three sites on the Iceland shelf. Thaumarchaeal intact polar lipids, in particular crenarchaeol, were detected at all stations and concentrations remained constant or decreased slightly upon incubation. No 13C incorporation in any IPL-GDGT was observed at stations 2 (clay-rich sediment) and 3 (organic-rich sediment). In bacterial/eukaryotic IPL-derived fatty acids at station 3, contrastingly, a large uptake of 13C label (up to + 80‰ ) was found. 13C was also respired during the experiment as shown by a substantial increase in the 13C content of the dissolved inorganic carbon. In IPL-GDGTs recovered from the sandy sediments at station 1, however, some enrichment in δ13C (1-4‰ ) was detected after incubation with bicarbonate and pyruvate. The low incorporation rates suggest a low activity of Thaumarchaeota in marine sediments and/or a low turnover rate of thaumarchaeal IPL-GDGTs due to their low degradation rates. Cell numbers and activity of sedimentary Thaumarchaeota based on IPL-GDGT measurements may thus have previously been overestimated.

  20. Prominent bacterial heterotrophy and sources of 13C-depleted fatty acids to the interior Canada Basin

    NASA Astrophysics Data System (ADS)

    Shah, S. R.;