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https://www.readbyqxmd.com/read/28220994/positional-enrichment-by-proton-analysis-pepa-a-one-dimensional-1-h-nmr-approach-for-13-c-stable-isotope-tracer-studies-in-metabolomics
#1
Maria Vinaixa, Miguel A Rodríguez, Suvi Aivio, Jordi Capellades, Josep Gómez, Nicolau Canyellas, Travis H Stracker, Oscar Yanes
A novel metabolomics approach for NMR-based stable isotope tracer studies called PEPA is presented, and its performance validated using human cancer cells. PEPA detects the position of carbon label in isotopically enriched metabolites and quantifies fractional enrichment by indirect determination of (13) C-satellite peaks using 1D-(1) H-NMR spectra. In comparison with (13) C-NMR, TOCSY and HSQC, PEPA improves sensitivity, accelerates the elucidation of (13) C positions in labeled metabolites and the quantification of the percentage of stable isotope enrichment...
February 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28213127/quantitation-of-lead-210-210-pb-using-lead-203-203-pb-as-a-massless-yield-tracer
#2
D May, A N Nelson, M K Schultz
Determination of Pb-210 ((210)Pb) in aqueous solution is a common radioanalytical challenge in environmental science. Widely used methods for undertaking these analyses (e.g., ASTM D7535) rely on the use of stable lead (Pb) as a yield tracer that takes into account losses of (210)Pb that inevitably occur during elemental/radiochemical separations of the procedures. Although effective, these methods introduce technical challenges that can be difficult to track and potentially introduce uncertainty that can be difficult to quantify...
February 14, 2017: Journal of Environmental Radioactivity
https://www.readbyqxmd.com/read/28212026/isotope-tracers-to-study-the-environmental-fate-and-bioaccumulation-of-metal-containing-engineered-nanoparticles-techniques-and-applications
#3
Yongguang Yin, Zhiqiang Tan, Ligang Hu, Sujuan Yu, Jingfu Liu, Guibin Jiang
The rapidly growing applicability of metal-containing engineered nanoparticles (MENPs) has made their environmental fate, biouptake, and transformation important research topics. However, considering the relatively low concentration of MENPs and the high concentration of background metals in the environment and in organisms, tracking the fate of MENPs in environment-related scenarios remains a challenge. Intrinsic labeling of MENPs with radioactive or stable isotopes is a useful tool for the highly sensitive and selective detection of MENPs in the environment and organisms, thus enabling tracing of their transformation, uptake, distribution, and clearance...
February 17, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28205600/non-reliance-of-metazoans-on-stromatolite-forming-microbial-mats-as-a-food-resource
#4
Gavin M Rishworth, Renzo Perissinotto, Matthew S Bird, Nadine A Strydom, Nasreen Peer, Nelson A F Miranda, Jacqueline L Raw
Grazing and burrowing organisms usually homogenise microalgal mats that form on benthic sediments of many aquatic ecosystems. In the absence of this disruption, microalgal mats can accrete laminated deposits (stromatolites). Stromatolites are rare in modern coastal ecosystems, but persist at locations where metazoans are largely excluded. This study aimed to assess the trophic structure at stromatolite locations where metazoans co-occur, to determine the grazing influence exerted by the metazoans on the stromatolite-forming microalgae (cyanobacteria and diatoms)...
February 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28205581/pathways-of-n-removal-and-n2o-emission-from-a-one-stage-autotrophic-n-removal-process-under-anaerobic-conditions
#5
Kai Li, Fang Fang, Han Wang, Chao Wang, Youpeng Chen, Jinsong Guo, Xixi Wang, Fuyang Jiang
To investigate the pathways of nitrogen (N) removal and N2O emission in a one-stage autotrophic N removal process during the non-aeration phase, biofilm from an intermittent aeration sequencing batch biofilm reactor (SBBR) and organic carbon-free synthetic wastewater were applied to two groups of lab-scale batch experiments in anaerobic conditions using a (15)N isotopic tracer and specific inhibitors, respectively. Then, the microbial composition of the biofilm was analysed using high-throughput sequencing...
February 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28196754/determination-of-groundwater-recharge-mechanism-in-the-deep-loessial-unsaturated-zone-by-environmental-tracers
#6
Zhi Li, Xi Chen, Wenzhao Liu, Bingcheng Si
Studying the groundwater recharge mechanism in regions with thick unsaturated zone can greatly improve our understanding of hydrological processes since these regions have complex groundwater processes. This study attempted to discuss the groundwater recharge in a region covered by loess over 130m deep in China's Loess Plateau. The water stable isotope, tritium and chloride in precipitation, groundwater and soil water were determined and used as inputs of mass balance methods. The tracer technique is found to be applicable and effective this region with thick unsaturated zone...
February 10, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28195703/mass-spectrometric-determination-of-uranium-and-thorium-in-high-radiopurity-polymers-using-ultra-low-background-electroformed-copper-crucibles-for-dry-ashing
#7
Isaac J Arnquist, Eric W Hoppe, Mary Bliss, Jay W Grate
A rapid new method for determining the U and Th mass concentrations in high radiopurity plastics is described, consisting of 1) dry ashing the plastic sample and tracers in low mass crucibles made of ultra low background electroformed copper (ULB EF-Cu) foil cut and folded into boats, 2) dissolving both the ash and the boat in acid, 3) performing a column separation to remove copper, and 4) determining the elements of interest by isotope dilution mass spectrometry. This method was demonstrated on both unfluorinated and fluorinated plastics, demonstrating high tracer recoveries and detection limits to pg/g (i...
February 14, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192957/integrated-extraction-chromatographic-separation-of-the-lithophile-elements-involved-in-long-lived-radiogenic-isotope-systems-rb-sr-u-th-pb-sm-nd-la-ce-and-lu-hf-useful-in-geochemical-and-environmental-sciences
#8
Christian Pin, Abdelmouhcine Gannoun
A fast and efficient sample preparation method in view of isotope ratio measurements is described, allowing the separation of 11 elements involved, either as "parent" or as "daughter" isotopes, in six radiogenic isotope systems used as chronometers and tracers in earth, planetary, and environmental sciences. The protocol is based on small extraction chromatographic columns, used either alone or in tandem, through which a single nitric acid solution is passed, without any intervening evaporation step. The columns use commercially available extraction resins (Sr resin, TRU resin, Ln resin, RE resin, and again Ln resin for isolating Sr and Pb, LREE then La-Ce-Nd-Sm, Lu(Yb), and Hf, Th, and U, respectively) along with an additional, in-house prepared resin for separating Rb...
February 9, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28192215/review-of-metabolic-pathways-activated-in-cancer-cells-as-determined-through-isotopic-labeling-and-network-analysis
#9
Wentao Dong, Mark A Keibler, Gregory Stephanopoulos
Cancer metabolism has emerged as an indispensable part of contemporary cancer research. During the past 10 years, the use of stable isotopic tracers and network analysis have unveiled a number of metabolic pathways activated in cancer cells. Here, we review such pathways along with the particular tracers and labeling observations that led to the discovery of their rewiring in cancer cells. The list of such pathways comprises the reductive metabolism of glutamine, altered glycolysis, serine and glycine metabolism, mutant isocitrate dehydrogenase (IDH) induced reprogramming and the onset of acetate metabolism...
February 10, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28190573/stable-sulfur-isotopes-identify-habitat-specific-foraging-and-mercury-exposure-in-a-highly-mobile-fish-community
#10
Meghan K Carr, Timothy D Jardine, Lorne E Doig, Paul D Jones, Lalita Bharadwaj, Brett Tendler, John Chételat, Pete Cott, Karl-Erich Lindenschmidt
Tracking the uptake and transfer of toxic chemicals, such as mercury (Hg), in aquatic systems is challenging when many top predators are highly mobile and may therefore be exposed to chemicals in areas other than their location of capture, confounding interpretation of bioaccumulation trends. Here we show how the application of a less commonly used ecological tracer, stable sulfur isotope ratios ((34)S/(32)S, or δ(34)S), in a large river-delta-lake complex in northern Canada allows differentiation of resident from migrant fishes, beyond what was possible with more conventional (13)C/(12)C and (15)N/(14)N measurements...
February 10, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28186521/diverging-effects-of-isotopic-fractionation-upon-molecular-diffusion-of-noble-gases-in-water-mechanistic-insights-through-ab-initio-molecular-dynamics-simulations
#11
Halua Pinto de Magalhães, Matthias S Brennwald, Rolf Kipfer
Atmospheric noble gases are routinely used as natural tracers to analyze gas transfer processes in aquatic systems. Their isotopic ratios can be employed to discriminate between different physical transport mechanisms by comparison to the unfractionated atmospheric isotope composition. In many applications of aquatic systems molecular diffusion was thought to cause a mass dependent fractionation of noble gases and their isotopes according to the square root ratio of their masses. However, recent experiments focusing on isotopic fractionation within a single element challenged this broadly accepted assumption...
February 10, 2017: Environmental Science. Processes & Impacts
https://www.readbyqxmd.com/read/28180034/surrogate-gas-prediction-model-as-a-proxy-for-%C3%AE-14-c-based-measurements-of-fossil-fuel-co2
#12
Kevin J Coakley, John B Miller, Stephen A Montzka, Colm Sweeney, Ben R Miller
The measured (14)C:(12)C isotopic ratio of atmospheric CO2 (and its associated derived Δ(14)C value) is an ideal tracer for determination of the fossil fuel derived CO2 enhancement contributing to any atmospheric CO2 measurement (Cff ). Given enough such measurements, independent top-down estimation of US fossil fuel-CO2 emissions should be possible. However, the number of Δ(14)C measurements is presently constrained by cost, available sample volume, and availability of mass spectrometer measurement facilities...
June 27, 2016: Journal of Geophysical Research. Atmospheres: JGR
https://www.readbyqxmd.com/read/28174267/k-isotopes-as-a-tracer-of-seafloor-hydrothermal-alteration
#13
Christopher A Parendo, Stein B Jacobsen, Kun Wang
At ocean spreading ridges, circulation of seawater through rock at elevated temperatures alters the chemical and isotopic composition of oceanic crust. Samples obtained from drilling into ocean floor and from ophiolites have demonstrated that certain isotope systems, such as (18)O/(16)O and (87)Sr/(86)Sr, are systematically modified in hydrothermally altered oceanic crust. Although K is known to be mobile during hydrothermal alteration, there have not yet been any K-isotope analyses of altered oceanic crustal materials...
February 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28168704/positron-emission-tomography-with-additional-%C3%AE-ray-detectors-for-multiple-tracer-imaging
#14
Tomonori Fukuchi, Takashi Okauchi, Mika Shigeta, Seiichi Yamamoto, Yasuyoshi Watanabe, Shuichi Enomoto
PURPOSE: Positron emission tomography (PET) is a useful imaging modality that quantifies the physiological distributions of radiolabeled tracers in vivo in humans and animals. However, this technique is unsuitable for multiple-tracer imaging because the annihilation photons used for PET imaging have a fixed energy regardless of the selection of the radionuclide tracer. This study developed a multi-isotope PET (MI-PET) system and evaluated its imaging performance. METHODS: Our MI-PET system is composed of a PET system and additional γ-ray detectors...
February 7, 2017: Medical Physics
https://www.readbyqxmd.com/read/28163219/probing-the-metabolic-phenotype-of-breast-cancer-cells-by-multiple-tracer-stable-isotope-resolved-metabolomics
#15
Andrew N Lane, Julie Tan, Yali Wang, Jun Yan, Richard M Higashi, Teresa W-M Fan
Breast cancers vary by their origin and specific set of genetic lesions, which gives rise to distinct phenotypes and differential response to targeted and untargeted chemotherapies. To explore the functional differences of different breast cell types, we performed Stable Isotope Resolved Metabolomics (SIRM) studies of one primary breast (HMEC) and three breast cancer cells (MCF-7, MDAMB-231, and ZR75-1) having distinct genotypes and growth characteristics, using (13)C6-glucose, (13)C-1+2-glucose, (13)C5,(15)N2-Gln, (13)C3-glycerol, and (13)C8-octanoate as tracers...
February 2, 2017: Metabolic Engineering
https://www.readbyqxmd.com/read/28161269/the-simultaneous-uptake-of-dietary-and-waterborne-cd-in-gastrointestinal-tracts-of-marine-yellowstripe-goby-mugilogobius-chulae
#16
Zhiqiang Guo, Na Gao, Yun Wu, Li Zhang
Aquatic animals under waterborne metal exposure are also very likely exposed to elevated dietary metals. This study quantified the simultaneous uptake of dietary and waterborne Cd in gastrointestinal tracts (GT) of marine yellowstripe goby using a dual stable isotope tracer method. The Cd spiked diet (10-100 μg g(-1), (111)Cd as tracers) were fed to the fish as a single meal, and then the fish were exposed to waterborne Cd (0-500 μg L(-1), (113)Cd as tracers) for 48 h, during which the time-course uptake of Cd in the stomach and intestine was determined...
February 1, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28158972/midcor-an-r-program-for-deciphering-mass-interferences-in-mass-spectra-of-metabolites-enriched-in-stable-isotopes
#17
Vitaly A Selivanov, Adrián Benito, Anibal Miranda, Esther Aguilar, Ibrahim Halil Polat, Josep J Centelles, Anusha Jayaraman, Paul W N Lee, Silvia Marin, Marta Cascante
BACKGROUND: Tracing stable isotopes, such as (13)C using various mass spectrometry (MS) methods provides a valuable information necessary for the study of biochemical processes in cells. However, extracting such information requires special care, such as a correction for naturally occurring isotopes, or overlapping mass spectra of various components of the cell culture medium. Developing a method for a correction of overlapping peaks is the primary objective of this study. RESULTS: Our computer program-MIDcor (free at https://github...
February 3, 2017: BMC Bioinformatics
https://www.readbyqxmd.com/read/28150819/legacy-of-contaminant-n-sources-to-the-no3-signature-in-rivers-a-combined-isotopic-%C3%AE-15-n-no3-%C3%AE-18-o-no3-%C3%AE-11-b-and-microbiological-investigation
#18
Cyrielle Briand, Mathieu Sebilo, Pascale Louvat, Thierry Chesnot, Véronique Vaury, Maude Schneider, Valérie Plagnes
Nitrate content of surface waters results from complex mixing of multiple sources, whose signatures can be modified through N reactions occurring within the different compartments of the whole catchment. Despite this complexity, the determination of nitrate origin is the first and crucial step for water resource preservation. Here, for the first time, we combined at the catchment scale stable isotopic tracers (δ(15)N and δ(18)O of nitrate and δ(11)B) and fecal indicators to trace nitrate sources and pathways to the stream...
February 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28149303/impact-of-leaf-traits-on-temporal-dynamics-of-transpired-oxygen-isotope-signatures-and-its-impact-on-atmospheric-vapor
#19
Maren Dubbert, Angelika Kübert, Christiane Werner
Oxygen isotope signatures of transpiration (δ E ) are powerful tracers of water movement from plant to global scale. However, a mechanistic understanding of how leaf morphological/physiological traits effect δ E is missing. A laser spectrometer was coupled to a leaf-level gas-exchange system to measure fluxes and isotopic signatures of plant transpiration under controlled conditions in seven distinct species (Fagus sylvatica, Pinus sylvestris, Acacia longifolia, Quercus suber, Coffea arabica, Plantago lanceolata, Oxalis triangularis)...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28138547/terrestrial-discharges-mediate-trophic-shifts-and-enhance-methylmercury-accumulation-in-estuarine-biota
#20
Sofi Jonsson, Agneta Andersson, Mats B Nilsson, Ulf Skyllberg, Erik Lundberg, Jeffra K Schaefer, Staffan Åkerblom, Erik Björn
The input of mercury (Hg) to ecosystems is estimated to have increased two- to fivefold during the industrial era, and Hg accumulates in aquatic biota as neurotoxic methylmercury (MeHg). Escalating anthropogenic land use and climate change are expected to alter the input rates of terrestrial natural organic matter (NOM) and nutrients to aquatic ecosystems. For example, climate change has been projected to induce 10 to 50% runoff increases for large coastal regions globally. A major knowledge gap is the potential effects on MeHg exposure to biota following these ecosystem changes...
January 2017: Science Advances
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