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Biochar influences soil biophysicochemical processes and nutrient availability, yet the effects of different biochar and soil water dynamics on carbon (C) and nitrogen (N) retention in the soil-plant systems remain unknown. Maize plants were grown in split-root pots filled with clay loam soil amended with wheat straw pellet biochar (WSP) and softwood pellet biochar (SWP) at 2% (w/w) and were either irrigated daily to 90% of water-holding capacity (FI) or irrigated with 70% volume of water used for FI to the whole root-zone (DI) or alternately to half root-zone (PRD) from the fourth leaf to grain-filling stage. Compared to the unamended controls, biochar amendment enhanced plant biomass and water-use efficiency, particularly when combined with PRD. Although the WSP amendment tended to decrease soil net N mineralization rate, it significantly increased C and N retention in the soil-plant systems. Compared to DI, PRD significantly increased soil respiration rate while lowering soil total organic C content. Moreover, PRD increased soil inorganic N content, which might be related to increased mineralization of soil organic C (SOC) and soil organic N (SON). Such effects might implicate that PRD outperformed DI in enhancing the mineralization of soil organic matter. Although PRD alone might not be a sustainable irrigation method because of greater C and N losses, biochar addition could alleviate these undesirable effects via depressing SOC and SON mineralization. Biochar amendment, especially WSP combined with PRD, could be a promising practice to increase maize growth and water-use efficiency while sustaining C and N retention in the soil-plant systems.Highlightscenter dot Effects of biochar addition and irrigation regimes on C and N retention in the soil-plant systems of maize were investigated.center dot Biochar increased plant N retention and maize growth. Partial root-zone drying (PRD) irrigation increased soil respiration rate and soil organic C and N mineralization.center dot Biochar addition combined with PRD improved maize growth, water-use efficiency, and sustained C and N retention in the soil-plant systems.

Laser ablation multi-collector mass spectrometry (LA-MC-ICP-MS) has emerged as the technique of choice for in situ measurements of Sr isotopes in geological minerals. However, the method poses analytical challenges and there is no widely adopted standardised approach to collecting these data or correcting the numerous potential isobaric inferences. Here, we outline practical analytical procedures and data reduction strategies to help establish a consistent framework for collecting and correcting Sr isotope measurements in geological materials by LA-MC-ICP-MS. We characterise a new set of plagioclase reference materials, which are available for distribution to the community, and present a new data reduction scheme for the Iolite software package to correct isobaric interferences for different materials and analytical conditions. Our tests show that a combination of Kr-baseline subtraction, Rb-peak-stripping using βRb derived from a bracketing glass reference material, and a CaCa or CaAr correction for plagioclase and CaCa or CaAr + REE 2+ correction for rock glasses, yields the most accurate and precise 87Sr/ 86Sr measurements for these materials. Using the analytical and correction procedures outlined herein, spot analyses using a beam diameter of 100 μm or rastering with a 50–65 μm diameter beam can readily achieve 87Sr/ 86Sr measurements for materials with -1 Sr.

One of the most prominent changes in the rhizospheric soil structure is associated with the formation of a strongly bound soil layer in the surroundings of the root, which is named rhizosheath. In this study, we investigated how root hair elongation, a ubiquitous root morphological trait, affect the stability of rhizosheath aggregates. Using 13CO2 pulse labeling, we tracked the fate of root-derived 13C inputted into the rhizosheath of two Zea mays L. genotypes with contrasting root hair elongation: a mutant with root hair defective elongation (rth3) and a corresponding wild type (WT). In addition, we also investigated the differences between two 13CO2 labeling approaches (single vs. multiple pulse labeling) in the distribution of 13C in the rhizosheath aggregates. We were able to demonstrate that the rhizosheath aggregate stability and the resulting aggregate size distribution follows the same mechanisms irrespective of the root hair elongation. This result reinforces the assumption that other soil properties are more decisive for the soil structure formation in the rhizosheath in comparison to root hair elongation. The majority of recently deposited root-derived C (57%) was found in the macroaggregates. Increasing the number of pulses (multiple pulse labeling approach) resulted in a higher 13C enrichment of the rhizosheath aggregates fractions in comparison to the application of a single pulse. While both labeling approaches resulted in a similar distribution of 13C in the rhizosheath aggregates, the higher enrichment given by multiple pulse labeling allowed the separation of significant differences between the genotypes in plant C allocation in the rhizosheath.

Актуальность исследования обусловлена необходимостью познания фундаментальной научной проблемы - железомарганцевый рудогенез Мирового океана. Помимо перспективного минерального сырья, морские железомарганцевые образования являются регистраторами условий седиментации в прошлом. Их формирование осуществляется при различных процессах, которые отражены в вещественном и изотопном составе. В настоящее время наименее изученным регионом Тихого океана является его северный сегмент. Цель: изучить изотопный состав Sr и Nd железомарганцевых корок северной Пацифики, формирующихся в условиях низкого терригенного потока. Методы: литолого-морфогенетический; рентгеноструктурный - определение минерального состава; масс- спектрометрический - определение химического и изотопного состава. Результаты. Исследованы железомарганцевые образования гайотов северной части Императорского хребта (Детройт, Сьюзей, Ханзей) и разломных зон Амлия, Рат и Стейлмейт, а также гайота Вулканолог (Магеллановы горы) в качестве сравнительного материала. На основании текстурно-структурных и минералого-геохимических особенностей изученные железомарганцевые образования отнесены к гидрогенным железомарганцевым коркам. Изотопный состав стронция изученных образцов находится в интервале от 0,70797 до 0,70919 (среднее 0,70885). При этом содержание стронция изменяется почти в три раза - от 660 до 1700 г/т. Зависимости изотопного состава от концентрации Sr не отмечается. Смещение величины отношения 87Sr/86Sr происходит к его значениям, характерным для вулканических пород, что является отражением высокого количества кварц-плагиоклазовой примеси в образце. Изотопный состав неодима в пересчете на εNd варьирует в интервале от -3,5 до -3,0, что соответствует современному значению глубинной воды северной Пацифики. Повышение значения εNd до -2,3 соответствует пробе с максимальной аллотигенной примесью. Минимальное значение величины εNd (-4,4) установлено в подошвенном слое железомарганцевой корки гайота Ханзей. Такое значение соответствует миоценовой глубинной воде северной Пацифики. Это является основанием полагать, что в миоцене на формирование вещественного состава железомарганцевых корок северной Пацифики оказывали влияние глубинные атлантические воды, поступающие через Панамский пролив. Прекращение их поставки в Тихий океан произошло, вероятно, пять млн лет назад. The relevance of the study is caused by the need to get knowledge of the fundamental scientific problem - the ferromanganese precipitation of the World Ocean. Marine ferromanganese deposits are records of sedimentation conditions in the past as well as promising mineral raw materials. Their formation is carried out under various processes, which are reflected in the bulk and isotopic composition of ferromanganese deposits. Currently, the least studied region of the Pacific Ocean is its northern segment. The main aim of the research is to study Sr and Nd isotopic composition of the ferromanganese crusts from the Norther Pacific, formed under low detrital influx. Methods: litho-morphology; x-ray diffraction - determination of the mineral composition; mass spectrometric - determination of the chemical and isotopic composition. Results. Ferromanganese deposits of the guyots of the northern part of the Imperial Range (Detroit, Suzei, Hanzei) and the Amliya, Rat and Stailmate fracture zones, as well as the Vulkanolog Guyot (Magellan Seamounts), as a comparative material, were studied. Based on the mineralogical and geochemical bulk compositions, the studied ferromanganese deposits are classified as hydrogenetic ferromanganese crusts. The strontium isotopic composition of the studied samples is in the range from 0,70797 to 0,70919 (average 0,70885), with most of the samples concentrated at 0,709. At the same time, the content of strontium changes almost three times from 660 to 1700 ppm. The dependence of the isotopic composition on the concentration is not observed. The displacement of 87Sr/86Sr occurs towards volcanic rocks, which reflects the high amount of quartz-plagioclase admixture in the sample. The isotopic composition of neodymium, in terms of εNd, varies in the range from -3,5 to -3,0, which corresponds to the modern deep seawater of the North Pacific. An increase in εNd to -2,3 corresponds to a sample with the maximum terrigenous admixture. The minimum value of εNd (-4,4) was found in the bottom layer of the ferromanganese crust from the Hanzei Guyot. This value corresponds to the Miocene North Pacific Deep water. This is a reason to believe that in the Miocene the formation of the bulk composition of the North Pacific ferromanganese crusts was under North Atlantic Deep Waters entering through the Panama Gateway. The end of North Atlantic Deep Waters delivery to the Pacific was finished about five million years ago.

In the current context of population growth and climate change, it is essential to effectively manage groundwater resources, to improve their quality, and to determine the behaviour of certain contaminants. Groundwater quality can be worsened most often by anthropogenic factors but can also be altered by natural factors depending on the chemical signatures of water sources (i.e., hydrochemical reactions) as a result of mixing processes. In these cases, the use of mixing calculations and multivariate statistical analysis (MSA) methods is crucial for determining the reactions that occur, the origin and fate of the detected compounds, ions or parameters, and the behaviour of the system. Thus, these methods ascertain processes that affect the chemical composition (i.e., quality) of groundwater bodies, and this information is needed for designing groundwater management strategies that exploit aquifers in a sustainable way. However, these methods are rarely employed, as few investigations that consider them focus on urban aquifers. Here, mixing calculations and other MSA methods that consider major ions and environmental isotopes are utilized in an aquifer located in a rural area associated with the Niebla-Posadas aquifer, Spain, where groundwater quality has deteriorated due to geogenic factors. This study proves the usefulness of these methods for deriving essential information that is needed (1) to properly manage the exploitation of aquifers, (2) to avoid the deterioration of groundwater bodies, and (3) to identify the reasons behind poor groundwater quality., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This study was supported by the “Agencia Estatal de Investigación” from the Spanish Ministry of Science and Innovation and the IDAEA-CSIC, a Centre of Excellence Severo Ochoa (CEX2018-000794-S). EP gratefully acknowledges the support received through the grant RYC2020-029225-I funded by MCIN/AEI/ 10.13039/501100011033 and by “ESF Investing in your future” and the Award for Scientific Research into Urban Challenges in the City of Barcelona 2020 (20S08708) from the Barcelona city council. RC gratefully acknowledges the financial support from the Balearic Island Government through the Margalida Comas postdoctoral fellowship programme (PD/036/2020). The authors would like to thank the European Commission, the Spanish Foundation for Science and Technology (FECYT) and Spanish State Research Agency (AEI) for funding in the frame of the collaborative international consortium (URBANWAT) financed under the 2018 Joint call of the WaterWorks2017 ERA-NET Cofund. This ERA-NET is an integral part of the activities developed by the Water JPI. Additionally, the authors would also like to thank the Ministry of Science, Innovation and Universities, for funding the project UNBIASED (Ref: RTI2018-097346-B-I00) under the 2018 call of the “Proyectos de I+D Retos Investigación.

The synthesis of new proteins and the degradation of old proteins in vivo can be quantified in serial samples using metabolic isotope labeling to measure turnover. Because serial biopsies in humans are impractical, we set out to develop a method to calculate the turnover rates of proteins from single human biopsies. This method involved a new metabolic labeling approach and adjustments to the calculations used in previous work to calculate protein turnover. We demonstrate that using a nonequilibrium isotope enrichment strategy avoids the time dependent bias caused by variable lag in label delivery to different tissues observed in traditional metabolic labeling methods. Turnover rates are consistent for the same subject in biopsies from different labeling periods, and turnover rates calculated in this study are consistent with previously reported values. We also demonstrate that by measuring protein turnover we can determine where proteins are synthesized. In human subjects a significant difference in turnover rates differentiated proteins synthesized in the salivary glands versus those imported from the serum. We also provide a data analysis tool, DeuteRater-H, to calculate protein turnover using this nonequilibrium metabolic

Ping Liu,1,2 Jing An,2 Huizhen Wu1,2 1Graduate School of Hebei Medical University, Shijiazhuang, People’s Republic of China; 2National Clinical Drug Monitoring Center, Department of Pharmacy, Hebei General Hospital, Shijiazhuang, People’s Republic of ChinaCorrespondence: Huizhen Wu, National Clinical Drug Monitoring Center, Department of Pharmacy, Hebei General Hospital, No. 348, West Heping Road, Shijiazhuang, 050051, People’s Republic of China, Email 13582005982@163.comPurpose: The present study aimed to establish and validate an isotope-dilution-UHPLC-MS/MS method for the determination of perampanel (PER) concentration and investigate the effect of eslicarbazepine acetate (ESL) on the pharmacokinetics of PER in rats.Methods: The rats were randomly divided into the control (0.5% CMC-Na) and experimental groups (ESL, 72 mg/kg), with six rats in each group. A single dose of PER (1 mg/kg) was administered after a week of repetitive 0.5% CMC-Na or ESL dosing (72 mg/kg); then, plasma samples were collected. Perampanel-d5 (PER-d5) was used as the internal standard (IS), liquid-liquid extraction of plasma samples was carried out using ethyl acetate, and chromatographic separation was carried out on a Titank C18 column (2.1 mm × 50 mm, 3.0 μm) using a gradient mobile phase consisting of 0.1% formic acid and acetonitrile at a flow rate of 0.3 mL/min.Results: PER had good linearity (0.3– 600 ng/mL, r > 0.999), and the accuracy, precision, recovery rate, and matrix effects (ME) met the Food and Drug Administration (FDA) guidelines. Compared to the control group, the area under the curve AUC0→t, AUC0→∞, and Cmax of PER in the experimental group decreased by 30.28%, 30.34%, and 46.94%, respectively, and CL increased by 32.08%.Conclusion: ESL could induce the metabolism of PER in rats and decreases plasma exposure to PER. Thus, the concomitant treatment with ESL may require a high dose of PER to achieve the same efficacy.Keywords: perampanel, eslicarbazepine acetate, pharmacokinetics, UHPLC-MS/MS, drug-drug interactions, Sprague–Dawley rats

Protein structural effects on the temperature (

In Germany, river monitoring for tritium started in the early 1970s. Today this monitoring network consists of 50 stations and includes stable isotopes. The stable isotope time series to the end of 2021 are at least four years and for some stations up to 30 years long. Daily river water samples were collected during an extraordinary dry season from October 2018 until end of January 2019 from six selected stations of the Rhine and five stations of the Elbe basin. The most dominating stable isotope effects in river water are the seasonal and altitude effects, but also a continental effect is visible. The isotopes indicate snow and ice melt contributions in the Rhine and Danube during the summer months and a consecutive dilution of these signals by mixing with tributary rivers. Close to the coasts in northern Germany, stable isotope patterns reflect influence of seawater and tides. Daily patterns during the dry season 2018/2019 surprisingly do not exhibit extreme changes but rather trends of enhanced groundwater contribution. Long-term continual data across scales are important for comparing and identifying hydrological processes in German river basins of different size and mean catchment altitudes, and highlight the benefits of a co-organized national network.

Background Edible insects are a novel source of animal protein. Moreover, edible insects contain iron concentrations similar to meat, potentially making them a valuable iron source for human consumers. Yet, it is unknown to what extent iron from insects is absorbed in humans. Objectives In this exploratory study, we assessed fractional iron absorption from house crickets (Acheta domesticus) consumed with refined (low-phytate, noninhibiting) or nonrefined (high-phytate, inhibiting) meals. Methods Intrinsically [57Fe]-labeled and control crickets were reared. Six iron-balanced experimental meals were randomly administered crossover to 20 iron-depleted females (serum ferritin, The American Journal of Clinical Nutrition, ISSN:0002-9165, ISSN:1938-3207

Over the past 70 years, the study of lipid metabolism has led to important discoveries in identifying the underlying mechanisms of chronic diseases. Advances in the use of stable isotopes and mass spectrometry in humans have expanded our knowledge of target molecules that contribute to pathologies and lipid metabolic pathways. These advances have been leveraged within two research paths, leading to the ability (1) to quantitate lipid flux to understand the fundamentals of human physiology and pathology and (2) to perform untargeted analyses of human blood and tissues derived from a single timepoint to identify lipidomic patterns that predict disease. This review describes the physiological and analytical parameters that influence these measurements and how these issues will propel the coming together of the two fields of metabolic tracing and lipidomics. The potential of data science to advance these fields is also discussed. Future developments are needed to increase the precision of lipid measurements in human samples, leading to discoveries in how individuals vary in their production, storage, and use of lipids. New techniques are critical to support clinical strategies to prevent disease and to identify mechanisms by which treatments confer health benefits with the overall goal of reducing the burden of human disease.

SummarySoil dwelling microorganisms are key players in the terrestrial carbon cycle, driving both the degradation and stabilization of soil organic matter. Bacterial community structure and function vary with respect to land-use, yet the ecological drivers of this variation remain poorly described and difficult to predict. We conducted a multi-substrate DNA-stable isotope probing experiment across cropland, old-field, and forest habitats to link carbon mineralization dynamics with the dynamics of bacterial growth and carbon assimilation. We tracked the movement of 13C derived from five distinct carbon sources as it was assimilated into bacterial DNA over time. We show that carbon mineralization, community composition, and carbon assimilation dynamics all differed with respect to land-use. We also show that microbial community dynamics affect carbon assimilation dynamics and are predictable from soil DNA content. Soil DNA yield is easy to measure and it predicts microbial community dynamics linked to soil carbon cycling.Originality-Significance StatementSoil dwelling microorganisms are key players in the terrestrial carbon cycle, driving both the degradation and stabilization of soil organic matter. Microbial communities vary with respect to land-use, but we still have an incomplete understanding of how variation in community structure links to variation in community function. DNA stable isotope probing (DNA-SIP) is a high-resolution method that can identify specific microbial taxa that assimilate carbon in situ. We conducted a large-scale multi-substrate DNA-SIP experiment to explore differences in bacterial activity across land-use regimes. We show that microbial community dynamics vary with land-use, that these dynamics are linked to soil carbon cycling, and that they are predicted from easily measured soil properties.

The carbon isotopic composition of methane (δ13CCH4) in natural gas from the Petišovci-Dolina oil and gas field (NE Slovenia) was measured for the first time in August and September 2021. The gas samples from different depths were taken from three wells: Dolina-deep (Pg-6) from the depth interval 3102–3104 m, Petišovci-deep (Pg-5) from the depth interval 2772–2795 m, and Petišovci-shallow (D-5) from the depth interval 1212–1250 m. According to the available composition dataset of gas, available from the Petrol Geo d.o.o. documentation, the “deep” gases sampled from the Pg-6 and Pg-5 wells consist of 85 % methane (C1), 11 % hydrocarbons heavier than methane (C2–C6) and 4 % CO2. The “shallow” gas from well D-5 contains more than 89 % methane, up to 11 % C2–C6 gases, while the CO2 content is negligible. The “deep« gas from the Pg-6 and Pg-5 wells has δ13CCH4 -36.7 ‰ and -36.6 ‰, respectively, while the “shallow” gas from the D-5 well has the δ13CCH4 of -38.6 ‰. The methane from the “shallow” gas is slightly enriched in the lighter 12C isotope. δ13CCH4 in the range from -38.6 to -36.6 ‰ clearly indicates the thermogenic origin of methane formed during the catagenesis phase of gas formation. Izotopsko sestavo metana (δ13CCH4) v naravnem (zemeljskem) plinu naftno-plinskega polja Petišovci-Dolina (Ormoško-selniška antiklinala, NE Slovenija) smo prvič merili v avgustu in septembru 2021. Plinske vzorce smo vzorčili iz različnih globin iz treh plinskih vrtin: iz Petišovci-globoka (Pg-6) iz globine 3102–3104 m, iz Petišovci-globoka (Pg-5) iz globine 2772–2795 m in iz Dolina-plitva (D-5) iz globine 1212–1250 m. Glede na dostopne podatke o sestavi plina iz dokumentacije Petrol Geo d.o.o., so “globoki” plini iz vrtin Pg-6 in Pg-5 sestavljeni iz 85 % metana (C1), iz 11 % ogljikovodikov, težjih od metana (C2–C6) in 4 % CO2. “Plitvi” plin iz vrtine D-5 je sestavljen iz več kot 89 % metana in do 11 % C2–C6, medtem ko je koncentracija CO2 zanemarljiva. “Globoki” plin iz vrtin Pg-6 in Pg-5 ima δ13CCH4 vrednost od -36.7 do -36.6 ‰, medtem ko ima “plitvi” plin iz vrtine D-5 δ13CCH4 -38.6 ‰. “Plitvi”plin iz vrtine D-5 je obogaten na lažjem 12C izotopu. Razpon δ13CCH4 od -38.6 do -36.6 ‰ jasno kaže termogeni izvor metana, ki je nastal v fazi katageneze nastajanja plina.

The recent Food and Agricultural Organization/World Health Organization/United Nations University expert consultations on protein requirements and quality have emphasized the need for the new Digestible Indispensable Amino Acid Score (DIAAS), as a measure of protein quality. This requires human measurements of the true ileal digestibility of individual indispensable amino acids (IAA) until the end of the small intestine. Digestibility is measured using standard oro-ileal balance methods, which can only be achieved by an invasive naso-ileal intubation in healthy participants or fistulation at the terminal ileum. Significant efforts have been made in last two decades to develop non-invasive or minimally invasive methods to measure IAA digestibility in humans. The application of intrinsically labeled (with stable isotopes like 13C, 15N and 2H) dietary proteins have helped in circumventing the invasive oro-ileal balance techniques and allowed for the differentiation between endo and exogenous protein digestibility. The non-invasive indicator amino acid oxidation (IAAO) technique, which is routinely employed to measure IAA requirements, has been modified to estimate metabolic availability (a sum of digestibility and utilization) of IAA in foods, but provide estimate for a single IAA at a time and burdensome for participants. The recently developed minimally invasive dual isotope tracer method measures small intestinal digestibility of multiple amino acids at once and is suitable for use in vulnerable groups and disease conditions. However, it remains to be validated against standard oro-ileal balance techniques. This review critically evaluates and compares the currently available stable isotope-based protein quality evaluation methods with a focus on the digestibility and metabolic availability measurements in humans. In the view of building reliable DIAAS database of various protein sources and subsequently supporting protein content claims in food labeling, a re-evaluation and harmonization of the available methods are necessary.

Polychlorinated naphthalenes (PCNs) have a structure similar to that of polychlorinated biphenyls (PCBs) and represent a new type of persistent organic pollutants (POPs) that are widely present in the environment and biological communities. PCNs can migrate and transform via different environmental media, which severely affects the health of humans and organisms. Researchers have devoted considerable focus on ambient air pollution. Although the current ambient air quality has not yet limited the concentration of PCNs, the Stockholm Convention has required parties to prohibit and eliminate their production and use. As one of the contracting parties, China is obligated to improve its environmental monitoring. In other words, the development of a method for monitoring PCNs in ambient air is important for understanding ambient air quality and safeguarding human health. PCNs are generally present at trace levels (pg/m

Understanding mobility and landscape use is important in reconstructing subsistence behavior, range, and group size, and it may contribute to our understanding of phenomena such as the dynamics of biological and cultural interactions between distinct populations of Upper Pleistocene humans. However, studies using traditional strontium isotope analysis are generally limited to identifying locations of childhood residence or nonlocal individuals and lack the sampling resolution to detect movement over short timescales. Here, using an optimized methodology, we present highly spatially resolved 87 Sr/ 86 Sr measurements made by laser ablation multicollector inductively coupled plasma mass spectrometry along the growth axis of the enamel of two marine isotope stage 5b, Middle Paleolithic Neanderthal teeth (Gruta da Oliveira), a Tardiglacial, Late Magdalenian human tooth (Galeria da Cisterna), and associated contemporaneous fauna from the Almonda karst system, Torres Novas, Portugal. Strontium isotope mapping of the region shows extreme variation in 87 Sr/ 86 Sr, with values ranging from 0.7080 to 0.7160 over a distance of c. 50 km, allowing short-distance (and arguably short-duration) movement to be detected. We find that the early Middle Paleolithic individuals roamed across a subsistence territory of approximately 600 km 2 , while the Late Magdalenian individual parsimoniously fits a pattern of limited, probably seasonal movement along the right bank of the 20-km-long Almonda River valley, between mouth and spring, exploiting a smaller territory of approximately 300 km 2 . We argue that the differences in territory size are due to an increase in population density during the Late Upper Paleolithic.

Ice cores from the northwestern Tibetan Plateau (NWTP) contain long records of regional climate variability, but refrozen meltwater and dust in these cores has hampered development of robust timescales. Here, we introduce an approach to dating the ice via the isotopic composition of atmospheric Osub2/subin air bubbles (δsup18/supOsubatm/sub), along with annual layer counting and radiocarbon dating. We provide a robust chronology for water isotope records (δsup18/supOsubice/suband d-excess) from three ice cores from the Guliya ice cap in the NWTP. The measurement of δsup18/supOsubatm/sub, although common in polar ice core timescales, has rarely been used on ice cores from low-latitude, high-altitude glaciers due to (1) low air pressure, (2) the common presence of refrozen melt that adds dissolved gases and reduces the amount of air available for analysis, and (3) the respiratory consumption of molecular oxygen (Osub2/sub) by micro-organisms in the ice, which fractionates the δsup18/supO of Osub2/subfrom the atmospheric value. Here, we make corrections for melt and respiration to address these complications. The resulting records of water isotopes from the Guliya ice cores reveal climatic variations over the last 15,000 y, the timings of which correspond to those observed in independently dated lake and speleothem records and confirm that the Guliya ice cap existed before the Holocene. The millennial-scale drivers of δsup18/supOsubice/subare complex and temporally variable; however, Guliya δsup18/supOsubice/subvalues since the mid-20th century are the highest since the beginning of the Holocene and have increased with regional air temperature.

Tracking the metabolic activity of whole soil communities can improve our understanding of the transformation and fate of carbon in soils. We used stable isotope metabolomics to trace 13C from nine labeled carbon sources into the water-soluble metabolite pool of an agricultural soil over time. Soil was amended with a mixture of all nine sources, with one source isotopically labeled in each treatment. We compared changes in the 13C-enrichment of metabolites with respects to carbon source and time over a 48-day incubation and contrasted differences between soluble versus insoluble sources. Whole soil metabolite profiles varied singularly by time, while the composition of 13C-labeled metabolites differed primarily by carbon source (R2 = 0.68) rather than time (R2 = 0.07) with source-specific differences persisting throughout incubations. The 13C-labeling of metabolites from insoluble carbon sources occurred at a slower rate than soluble sources but yielded a higher average atom % 13C in metabolite markers of biomass (amino acids and nucleic acids). The 13C-enrichment of metabolite markers of biomass stabilized at between 5 – 15 atom % 13C by the end of incubations. Temporal patterns in the 13C-enrichment of TCA cycle intermediates, nucleobases (uracil and thymine), and by-products of DNA salvage (allantoin) closely tracked microbial activity. Our results demonstrate that metabolite production in soils is driven by the carbon source supplied to the community, and that the fate of carbon in metabolite profiles do not tend to converge over time as a result of ongoing microbial processing and recycling.ImportanceCarbon metabolism in soil remains poorly described due to the inherent difficulty of obtaining information on the microbial metabolites produced by complex soil communities. Our study demonstrates the use of stable isotope probing (SIP) to study carbon metabolism in soil by tracking 13C from supplied carbon sources into metabolite pools and biomass. We show that differences in the metabolism of sources influences the fate of carbon in soils. Heterogeneity in 13C-metabolite profiles corresponded with compositional differences in the metabolically active populations, providing a basis for how microbial community composition is correlated with the quality of soil carbon. Our study demonstrates the application of SIP-metabolomics in studying soils and identifies several metabolite markers of growth, activity, and other aspects of microbial function.

Bacteria catalyze the formation and destruction of soil organic matter, but the bacterial dynamics in soil that govern carbon (C) cycling are not well understood. Life history strategies explain the complex dynamics of bacterial populations and activities based on trade-offs in energy allocation to growth, resource acquisition, and survival. Such trade-offs influence the fate of soil C, but their genomic basis remains poorly characterized. We used multisubstrate metagenomic DNA stable isotope probing to link genomic features of bacteria to their C acquisition and growth dynamics. We identify several genomic features associated with patterns of bacterial C acquisition and growth, notably genomic investment in resource acquisition and regulatory flexibility. Moreover, we identify genomic trade-offs defined by numbers of transcription factors, membrane transporters, and secreted products, which match predictions from life history theory. We further show that genomic investment in resource acquisition and regulatory flexibility can predict bacterial ecological strategies in soil. IMPORTANCE Soil microbes are major players in the global carbon cycle, yet we still have little understanding of how the carbon cycle operates in soil communities. A major limitation is that carbon metabolism lacks discrete functional genes that define carbon transformations. Instead, carbon transformations are governed by anabolic processes associated with growth, resource acquisition, and survival. We use metagenomic stable isotope probing to link genome information to microbial growth and carbon assimilation dynamics as they occur in soil. From these data, we identify genomic traits that can predict bacterial ecological strategies which define bacterial interactions with soil carbon.

Coastal rivers contributed the majority of anthropogenic nitrogen (N) loads to coastal waters, often resulting in eutrophication and hypoxia zones. Accurate N source identification is critical for optimizing coastal river N pollution control strategies. Based on a 2-year seasonal record of dual stable isotopes (δ15N-NO– 3 and δ18O-NO– 3) and water quality parameters, this study combined the dual nitrate (NO– 3) stable isotope method and the absolute principal component score-multiple linear regression (APCS-MLR) model to elucidate N dynamics and sources in two coastal rivers of Hangzhou Bay. Water quality/trophic level indices indicated light-to-moderate eutrophication status for the studied rivers. Spatio-temporal variability of water quality was associated with seasonal agricultural, aquaculture and domestic activities, as well as the seasonal precipitation pattern. The APCS-MLR model identified soil + domestic wastewater (69.5%) and aquaculture tailwater (22.2%) as the major nitrogen pollution sources. Further, the dual stable isotope method identified soil N, aquaculture tailwater, domestic wastewater and atmospheric deposition N contributions of 35.3 ±21.1%, 29.7 ±17.2%, 27.9 ±14.5%, and 7.2 ±11.4% to riverine NO– 3 in the Cao’e River (CER) and 34.4 ±21.3%, 29.5 ±17.2%, 27.4 ±14.7%, and 8.7 ±12.8% in the Jiantang River (JTR), respectively. The APCS-MLR model and dual stable isotope method showed consistent results for riverine N source identification. Combining these two methods for riverine N source identifications effectively distinguished the mix-source components from the APCS-MLR method and alleviated the high cost of stable isotope analysis, thereby providing reliable N source apportionment results with low requirements for water quality sampling and isotope analysis costs. Moreover, this study highlights the importance of soil N management and aquaculture tailwater treatment in coastal river N pollution control.

The continuous advances in mass spectrometry techniques have pushed forward the frontiers of all branches of the isotope biogeochemistry field. In environmental studies, different isotope ratios as determined in different reservoirs offer the opportunity, for example, to identify pollution sources and to trace metal fluxes within the trophic web and in dietary studies. Despite its relevance, trace metal isotope biogeochemistry is infrequently taught in undergraduate courses because it demands a rather high level of complexity of teaching strategies and abstraction capacity from students. Additionally, available didactic material for introducing mixing source modeling with stable isotopes relevant to biogeochemistry is scarce. In this context, the present study applies a visually appealing didactic strategy based on the analogy between colors (analog domain) and isotopic compositions (target domain), in order to encourage and assist the teaching–learning processes of this new subject in environmental science and chemistry classes. We demonstrate how familiar and simple concepts can be applied for introducing challenging subjects. In a setting that restricts in-person academic activities such as during a pandemic, the development of appealing visual approaches is imperative to engage students during online classes. The didactic strategy proposed herein was put to the test during remotely taught classes on the topic of “Environmental Impact Assessment Methodology” (winter 2021, 18 students) and “Environmental Contamination” (summer 2020, 18 students, and winter 2021, 20 students) of the Postgraduate Program in Geochemistry at the Fluminense Federal University (Rio de Janeiro, Brazil). Students’ feedback was very positive; they found our approach stimulating, and it helped them to better visualize, understand, and interpret the targeted learning outcomes.

Monitoring mercury (Hg) levels in biota is considered an important objective for the effectiveness evaluation of the Minamata Convention. While many studies have characterized Hg levels in organisms at multiple spatiotemporal scales, concentration analyses alone often cannot provide sufficient information on the Hg exposure sources and internal processes occurring within biota. Here, we review the decadal scientific progress of using Hg isotopes to understand internal processes that modify the speciation, transport, and fate of Hg within biota. Mercury stable isotopes have emerged as a powerful tool for assessing Hg sources and biogeochemical processes in natural environments. A better understanding of the tissue location and internal mechanisms leading to Hg isotope change is key to assessing its use for biomonitoring. We synthesize the current understanding and uncertainties of internal processes leading to Hg isotope fractionation in a variety of biota, in a sequence of better to less studied organisms (i.e., birds, marine mammals, humans, fish, plankton, and invertebrates). This review discusses the opportunities and challenges of using certain forms of biota for Hg source monitoring and the need to further elucidate the physiological mechanisms that control the accumulation, distribution, and toxicity of Hg in biota by coupling new techniques with Hg stable isotopes.

Synopsis The introduction of laboratory methods to animal dietary studies has allowed researchers to obtain results with accuracy and precision, not possible with observational techniques. For example, DNA barcoding, or the identification of prey with taxon-specific DNA sequences, allows researchers to classify digested prey tissues to the species-level, while stable isotope analysis paired with Bayesian mixing models can quantify dietary contributions by comparing a consumer's isotopic values to those derived from their prey. However, DNA-based methods are currently only able to classify, but not quantify, the taxa present in a diet sample, while stable isotope analysis can only quantify dietary taxa that are identified a priori as prey isotopic values are a result of life history traits, not phylogenetic relatedness. Recently, researchers have begun to couple these techniques in dietary studies to capitalize on the reciprocal benefits and drawbacks offered by each approach, with some even integrating DNA-based results directly into Bayesian mixing models as informative priors. As the informative priors used in these models must represent known dietary compositions (e.g., percentages of prey biomasses), researchers have scaled the DNA-based frequency of occurrence of major prey groups so that their normalized frequency of occurrence sums to 100%. Unfortunately, such an approach is problematic as priors stemming from binomial, DNA-based data do not truly reflect quantitative information about the consumer's diet and may skew the posterior distribution of prey quantities as a result. Therefore, we present a novel approach to incorporate DNA-based dietary information into Bayesian stable isotope mixing models that preserves the binomial nature of DNA-based results. This approach uses community-wide frequency of occurrence or logistic regression-based estimates of prey occurrence to dictate the probability that each prey group is included in each mixing model iteration, and, in turn, the probability that each iteration's results are included in the posterior distribution of prey composition possibilities. Here, we demonstrate the utility of this method by using it to quantify the prey composition of nestling Louisiana waterthrush (Parkesia motacilla).

Tracking Saharan–Sahelian dust across the globe is essential to elucidate its effects on Earth’s climate, radiation budget, hydrologic cycle, nutrient cycling, and also human health when it seasonally enters populated/industrialized regions of Africa, Europe, and North America. However, the elemental composition of mineral dust arising locally from construction activities and aeolian soil resuspension overlaps with African dust. Therefore, we derived a novel “isotope-resolved chemical mass balance” (IRCMB) method by employing radiogenic strontium, neodymium, and hafnium isotopes to accurately differentiate and quantitatively apportion collinear proximal and synoptic-scale crustal and anthropogenic mineral dust sources. IRCMB was applied to two air masses that transported African dust to Barbados and Texas to track particulate matter (PM) spikes at both locations. During Saharan–Sahelian intrusions, the radiogenic content of urban PM(2.5) increased with respect to (87)Sr/(86)Sr and (176)Hf/(177)Hf but decreased in terms of (143)Nd/(144)Nd, demonstrating the ability of these isotopes to sensitively track African dust intrusions even in complex metropolitan atmospheres. The principal aerosol strontium, neodymium, and hafnium end members were concrete dust and soil, soil and motor vehicles, and motor vehicles and North African dust, respectively. IRCMB separated and quantified local soil and distal crustal dust even when PM(2.5) concentrations were low, opening a promising source apportionment avenue for urbanized/industrialized atmospheres.

Protein kinetic responses to nutrition and exercise interventions are commonly evaluated using a primed-constant infusion of stable isotope tracers. While this methodology is state-of-the-art, the required preparation at a certified pharmacy makes the utilization of isotope infusion both expensive and logistically cumbersome. Oral tracer ingestion has been used to quantify 24-h whole-body protein status; however, this does not permit examination of acute interventional effects. Ingestion of a priming bolus, followed by continuous ingestion of stable isotope tracer in a 'sip feeding' fashion may provide a more feasible alternative for quantifying acute kinetic responses. Therefore, the purpose of this study was to evaluate the viability of a primed continuous oral sip-ingestion method of stable isotope tracers for the evaluation of whole-body protein kinetics.In a randomized, crossover design, eight healthy adults (63% female; Age: 29.4 ± 5.8 yrs; BMI: 24.3 ± 2.7 kg/mUsing the sip feed method, NB, PS, and hydroxylation were significantly increased with ingestion of protein (p 0.05) during the postprandial period, regardless of amount of protein ingested; ΔNB from the postabsorptive to postprandial period was significantly greater for high compared to low protein (p = 0.026; low = 6.2 ± 5.1 g protein·240 minThe current study provides preliminary evidence that continuous oral sip-feeding of stable isotope tracer is a feasible method that provides physiologically relevant measures of protein metabolism. Assessments of variance and individual responses revealed high measurement variability with the sip-feed method compared to previously published constant infusion responses, but ΔNB, ΔPS, and ΔPB were comparable. In situations where constant infusion is not feasible, oral sip-feeding could be used as an alternative method for measurement of acute, postprandial protein metabolism.

Mass cytometry (MC) is a recent technology that pairs plasma-based ionization of cells in suspension with time-of-flight (TOF) mass spectrometry to sensitively quantify the single-cell abundance of metal-isotope-tagged affinity reagents to key proteins, RNA, and peptides. Given the ability to multiplex readouts (~50 per cell) and capture millions of cells per experiment, MC offers a robust way to assay rare, transitional cell states that are pertinent to human development and disease. Here, we review MC approaches that let us probe the dynamics of cellular regulation across multiple conditions and sample types in a single experiment. Additionally, we discuss current limitations and future extensions of MC as well as computational tools commonly used to extract biological insight from single-cell proteomic datasets.

Актуальность исследования обусловлена отсутствием информации об уровнях содержания в почвах Семипалатинского испытательного полигона техногенного радионуклида 151Sm. Расчетное количество 151Sm, которое могло быть рассеяно во время наземных и атмосферных испытаний ядерных зарядов, проведенных на Семипалатинском испытательном полигоне, составляет 6,1·105 Ки. Как известно, почва является депонирующей системой, накапливающей различные токсичные, вредные вещества и радионуклиды. В результате ветровой и водной эрозии почв, поглощения радионуклидов растениями, может происходить их дальнейшее перераспределение и миграция, в результате чего радионуклиды могут поступать в организм человека, приводя к его облучению. Цель: разработка способа радиохимического определения 151Sm в почвах Семипалатинского испытательного полигона с использованием метода жидкостной сцинтилляционной спектрометрии. Объекты: поверхностные пробы почвы, отобранные на территории Семипалатинского испытательного полигона. Основными критериями при выборе образцов было наличие в них 137Cs как возможного индикатора присутствия 151Sm, и отсутствие радиоактивных изотопов Eu как основного мешающего радионуклида. Значения удельной активности 137Cs в исследуемых образцах варьировали от 3,6 до 780 Бк/кг. Метод. Способ определения 151Sm включает полное кислотное разложение исследуемых образцов почвы концентрированными растворами кислот (HF, HNO3), выделение и радиохимическую очистку с использованием ионообменных смол, а также осаждение малорастворимых соединений. Удельная активность 151Sm определялась с помощью ультра-низкофонового жидкосцинтилляционного спектрометра Quantulus 1220. Кривая эффективности регистрации 151Sm от гашения в образце была построена с использованием метода CIEMAT/NIST. Для измерения концентрации изотопов самария использовался массспектрометр Agilent 7700x, содержание гамма-излучателей оценивалось с помощью гамма-спектрометров ВЕ-5030 и GEM 5825. Результаты. Разработан способ определения 151Sm в пробах почвы с использованием метода жидкостной сцинтилляционной спектрометрии. Средний химический выход составил 83 %, предел обнаружения - 0,01 Бк/г для времени измерения 60 мин. Зафиксированные значения удельной активности 151Sm составили диапазон от 158 до 290 Бк/кг. The relevance. One of the relatively long-lived nuclear fission products is 151Sm (T1/2~90 years). The total cumulative yield of 151Sm upon fission of the isotopes 235U, 239Pu and 238U is 0,46, 1,29 and 0,83 %, respectively. The estimated amount of 151Sm that could have been dispersed during ground and atmospheric tests at Semipalatinsk test site is 6,1·105 Ci. The current situation with the levels of radioactive contamination of the soil cover with this radionuclide is still unknown. The aim of the research is to develop the method for radiochemical determination of 151Sm in Semipalatinsk test site soils using liquid scintillation spectrometry. Objects. Surface soil samples were taken from the territory of the former Semipalatinsk test site. The main sampling criteria were the presence of 137Cs as a possible indicator of the presence of 151Sm and the absence of radioactive isotopes of Eu as the main interfering radionuclide. The specific activity of 137Cs in the samples under study varied from 3,6 to 780 Bq/kg. Methods. The proposed method for 151Sm determination includes complete dissolution of the samples with concentrated acids (HF and HNO3 and their mixtures), isolation and radiochemical purification with ion exchange resins, as well as precipitation of poorly soluble substances. In order to determine the chemical yield, 0,5 mg of Sm-carrier was added to each sample as an indicator. The quenching curve for 151Sm was prepared using the CIEMAT/NIST approach. The 151Sm specific activity was measured using Quantulus 1220 LSC. Results. The radiochemical purification of the 151Sm fraction from interfering beta emitters was analyzed and evaluated, as well as the effect of natural samarium on the chemical yield. The contribution of natural samarium regarding to the clarke does not exceed 8 % (for 5 g soil sample), and in relation to the experimentally measured amount - 0,5 %. However, it seems more expedient to double the amount of the added carrier (up to 1 mg per sample), which will reduce the contribution of natural samarium to 4 % (relative to the clarke). Gammaspectrometric measurements of the isolated samarium fraction indicate the possibility of its contamination with some residual amount of strontium isotopes (85Sr was used as an indicator), the maximum amount of which, obviously, does not exceed 5 %. The specific activity of all other considered radionuclides is below the detection limits. MDA value obtained for 151Sm in this work was in the region of 0,01 Bq/g. The mean chemical recovery of 151Sm was 83 %. The specific activity of 151Sm in surface soil ranged from 158 to 290 Bq/kg.

To assess the prognostic capabilities of various diagnostic modalities for childhood brachial plexus injuries (BPIs) and brachial plexus birth injury (BPBI) and postneonatal BPI.In this single-center retrospective cross-sectional study, we examined children with BPIs diagnosed or confirmed by electrodiagnostic studies between 2013 and 2020, and compared the prognostic value of various components of the electrophysiologic findings, magnetic resonance imaging (MRI) data, and the Active Movement Scale (AMS). We developed scoring systems for electrodiagnostic studies and MRI findings, including various components of nerve conduction studies and electromyography (EMG) for electrodiagnostic studies.We identified 21 children (10 females and 11 males) aged 8 days to 21 years (mean 8y 6.95mo) who had a total of 30 electrodiagnostic studies, 14 brachial plexus MRI studies, and 10 surgical procedures. Among the diagnostic modalities assessed, brachial plexus MRI scores, EMG denervation scores, and mean total EMG scores were the most valuable in predicting surgical versus non-surgical outcomes. Correspondingly, a combined MRI/mean total EMG score provided prognostic value.Brachial plexus MRI scores and specific electrodiagnostic scores provide the most accurate prognostic information for children with BPI. Our grading scales can assist a multidisciplinary team in quantifying results of these studies and determining prognosis in this setting.A new scoring system to quantify results of electrodiagnostic and magnetic resonance imaging (MRI) studies is presented. Severity of denervation has good prognostic value for childhood brachial plexus injuries (BPIs). Composite electromyography scores have good prognostic value for childhood BPIs. Brachial plexus MRI has good prognostic value for childhood BPIs.

Using a combination of experimental studies, theory, simulation, and modeling, we investigate the hydrogen atom transfer (HAT) reaction by the high-valent ferryl cytochrome P450 (CYP) intermediate known as Compound I, a species that is central to innumerable and important detoxification and biosynthetic reactions. The P450 decarboxylase known as OleT converts fatty acids, a sustainable biological feedstock, into terminal alkenes and thus is of high interest as a potential means to produce fungible biofuels. Previous experimental work has established the intermediacy of Compound I in the C─C scission reaction catalyzed by OleT and an unprecedented ability to monitor the HAT process in the presence of bound fatty acid substrates. Here, we leverage the kinetic simplicity of the OleT system to measure the activation barriers for CYP HAT and the temperature dependence of the substrate

RNA is central to the proper function of cellular processes important for life on earth and implicated in various medical dysfunctions. Yet, RNA structural biology lags significantly behind that of proteins, limiting mechanistic understanding of RNA chemical biology. Fortunately, solution NMR spectroscopy can probe the structural dynamics of RNA in solution at atomic resolution, opening the door to their functional understanding. However, NMR analysis of RNA, with only four unique ribonucleotide building blocks, suffers from spectral crowding and broad linewidths, especially as RNAs grow in size. One effective strategy to overcome these challenges is to introduce NMR-active stable isotopes into RNA. However, traditional uniform labeling methods introduce scalar and dipolar couplings that complicate the implementation and analysis of NMR measurements. This challenge can be circumvented with selective isotope labeling. In this review, we outline the development of labeling technologies and their application to study biologically relevant RNAs and their complexes ranging in size from 5 to 300 kDa by NMR spectroscopy.

A method using diffusive gradients in thin films (DGT) for the accurate quantification of trace-level (μg L

A ‘principles and practice’ tutorial-style review of the application of solution-phase NMR in the analysis of the mechanisms of homogeneous organic and organometallic reactions and processes. This review of 345 references summarises why solution-phase NMR spectroscopy is uniquely effective in such studies, allowing non-destructive, quantitative analysis of the wide range of nuclei common to organic and organometallic reactions, providing exquisite structural detail, and using instrumentation that is routinely available in most chemistry research facilities. The review is in two parts. The first comprises an introduction to general techniques and equipment, and guidelines for their selection and application. Topics include practical aspects of the reaction itself, reaction monitoring techniques, NMR data acquisition and processing, analysis of temporal concentration data, NMR titrations, DOSY, and the use of isotopes. The second part comprises a series of 15 'Case Studies', each selected to illustrate specific techniques and approaches discussed in the first part, including in situ NMR (1/2H, 10/11B, 13C, 15N, 19F, 29Si, 31P), kinetic and equilibrium isotope effects, isotope entrainment, isotope shifts, isotopes at natural abundance, scalar coupling, kinetic analysis (VTNA, RPKA, simulation, steady-state), stopped-flow NMR, flow NMR, rapid injection NMR, pure shift NMR, dynamic nuclear polarisation, 1H/19F DOSY NMR, and in situ illumination-NMR

The stable water isotopic composition in firn and ice cores provides valuable information on past climatic conditions. Because of uneven accumulation and post-depositional modifications on local spatial scales up to hundreds of meters, time series derived from adjacent cores differ significantly and do not directly reflect the temporal evolution of the precipitated snow isotopic signal. Hence, a characterization of how the isotopic profile in the snow develops is needed to reliably interpret the isotopic variability in firn and ice cores. By combining digital elevation models of the snow surface and repeated high-resolution snow sampling for stable water isotope measurements of a transect at the East Greenland Ice-core Project campsite on the Greenland Ice Sheet, we are able to visualize the buildup and post-depositional changes of the upper snowpack across one summer season. To this end, 30 cm deep snow profiles were sampled on six dates at 20 adjacent locations along a 40 m transect. Near-daily photogrammetry provided snow height information for the same transect. Our data shows that erosion and redeposition of the original snowfall lead to a complex stratification in the δ18O signature. Post-depositional processes through vapor-snow exchange affect the near surface snow with d-excess showing a decrease in surface and near-surface layers. Our data suggests that the interplay of stratigraphic noise, accumulation intermittency, and local post-depositional processes form the proxy signal in the upper snowpack. publishedVersion

The consumption of grape juice has been growing significantly, so its quality is becoming an issue of great importance, both for the consumer and for the industry. However, identifying adulteration in juice is a great challenge and requires a reliable analytical process. The isotope ratio (18O/16O) is an important tool to determine the addition of exogenous water in beverages, however, there is no official method for juice in Brazil. This study aimed to develop and validate a method for detecting exogenous water in grape juice through isotopic analysis of 18O/16O. The development and validation of the analytical method were performed using Isotope Ratio Mass Spectrometry (IRMS). The effect of temperature and evaporation of δ18O in experimental juices was evaluated, and reference values were found for juices based on the δ 18O of musts. The influence of the juice industrial production process on 18O values was verified, and commercial juices were evaluated in relation to the values of reference regarding the addition of water. The temperature and evaporation parameters did not influence the results of the 18O of the juice, as they presented differences lower than the method uncertainty. The heat exchanger system did not influence the proposed method. The reference values for juice can come from the musts, without affecting the interpretation of the final results. Of the thirty real juices analyzed, nine had exogenous water, three proved to be reconstituted juices and eighteen were considered to have no exogenous water. The method proposed and validated in this study presented values for the limit of detection (LOD) of 0.24‰, the limit of quantification (LOQ) of 0.97‰ and measurement uncertainty of 0.71‰, proving to be effective for the detection of exogenous water in grape juice, through of the analysis of the isotopic ratio of 18O/16O by IRMS. Resumo O consumo de suco de uva vem crescendo significativamente, tornando sua qualidade uma questão de grande importância, tanto para o consumidor quanto para a indústria. Assim, identificar a adulteração em suco é um grande desafio e requer um processo analítico confiável. A razão isotópica (18O/16O) é uma importante ferramenta para determinar a adição de água exógena em bebidas, porém não existe um método oficial para suco, no Brasil. O objetivo deste trabalho foi desenvolver e validar um método para detecção de água exógena em suco de uva através da razão isotópica do 18O/16O. A validação e o desenvolvimento do método analítico foram realizados através de espectrometria de massas de razão isotópica (IRMS). Foi avaliado o efeito da temperatura e da evaporação de δ18O em sucos experimentais, sendo encontrados valores de referência para sucos baseado no δ18O de mostos. Também foi verificada a influência do processo industrial de fabricação de sucos nos valores de δ18O e avaliados sucos comerciais em relação aos valores de referência quanto à adição de água. Os parâmetros de temperatura e evaporação não influenciaram os resultados do δ18O do suco, pois apresentaram diferenças inferiores à incerteza do método. O sistema trocador de calor não exerceu influência sobre o método proposto. Os valores de referência para suco podem ser provenientes dos mostos, sem prejudicar a interpretação dos resultados finais. Dos trinta sucos comerciais analisados, nove apresentaram água exógena, três demonstraram ser sucos reconstituídos e 18 foram considerados com ausência de água exógena. O método proposto e validado neste estudo apresentou valores para o limite de detecção (LD) de 0,24‰, limite de quantificação (LQ) de 0,97‰ e incerteza de medição de 0,71‰, mostrando-se eficaz para a detecção de água exógena em suco de uva, por meio da análise da razão isotópica do 18O/16O por IRMS.

Ikaite and pseudomorphs thereafter (“glendonites”) are a potentially powerful tool for palaeoclimatic studies, as a low-temperature proxy. However, much uncertainty still surrounds the drivers of ikaite formation, in particular prerequisite thermal and chemical conditions. Furthermore, the ikaite toglendonite transformation is not fully understood, and it was unclear which calcite phases in glendonites were ikaite-derived and which were later diagenetic calcites. This leads to difficulties in choosing which phase to analyse in order to reconstruct the original ikaite growth environmental conditions. Petrographicexamination of air-transformed ikaite from the Isatkoak Lagoon in Utqiaġvik, Alaska, confirms that both ’Type I’ and ’Type II’ calcite phases seen in glendonites are directly derived from ikaite breakdown and not from secondary sources. Clumped isotope temperature reconstructions for transformed ikaites from Utqiaġvik, and comparison to Recent glendonites from the White Sea, Russia, confirm that clumped isotope thermometry may be used to reconstruct ikaite growth temperatures, whilst stable isotopes and minor elemental analysis reveal that a range of geochemical conditions characterise ikaite growth sites

To evaluate the prevalence and clinical significance of nonuniform technetium (Patients with GD, referred between July 2005 and March 2018, had TcOf the 276 GD patients (mean age, 49.8 years; 84% female), 25 (9.0%) had nonuniform TcNonuniform radio-isotope uptake is seen in 1 in 11 patients with GD which could be misdiagnosed as toxic multinodular goitre if TRAb levels are not measured. Treatment of GD patients with nonuniform radio-isotope uptake with ATD therapy as first-line appears to be equally effective as compared with those with uniform uptake. TRAb testing should be the main diagnostic test for patients with suspected GD with radio-labelled uptake scans being reserved for those who are TRAb negative.

Background & aimsElective surgery induces skeletal muscle wasting driven by an imbalance between muscle protein synthesis and breakdown. From examination of diverse stable isotope tracer techniques, the dynamic processes driving this imbalance are unclear. This meta-analysis aimed to elucidate the mechanistic driver(s) of postoperative protein catabolism through stable isotope assessment of protein turnover before and after abdominal surgery.MethodsMeta-analysis was performed of randomized controlled trials and cohort studies in patients undergoing elective abdominal surgery that contained measurements of whole-body or skeletal muscle protein turnover using stable isotope tracer methodologies pre- and postoperatively. Postoperative changes in protein synthesis and breakdown were assessed through subgroup analysis of tracer methodology and perioperative care.ResultsSurgery elicited no overall change in protein synthesis [standardized mean difference (SMD) ?0.47, 95% confidence interval (CI): ?1.32, 0.39, p = 0.25]. However, subgroup analysis revealed significant suppressions via direct-incorporation methodology [SMD -1.53, 95%CI: ?2.89, ?0.17, p = 0.03] within skeletal muscle. Changes of this nature were not present among arterio-venous [SMD 0.61, 95%CI: ?1.48, 2.70, p = 0.58] or end-product [SMD -0.09, 95%CI: ?0.81, 0.64, p = 0.82] whole-body measures. Surgery resulted in no overall change in protein breakdown [SMD 0.63, 95%CI: ?0.06, 1.32, p = 0.07]. Yet, separation by tracer methodology illustrated significant increases in urinary end-products (urea/ammonia) [SMD 0.70, 95%CI: 0.38, 1.02, p < 0.001] that were not present among arterio-venous measures [SMD 0.67, 95%CI: ?1.05, 2.38, p = 0.45].ConclusionsElective abdominal surgery elicits suppressions in skeletal muscle protein synthesis that are not reflected on a whole-body level. Lack of uniform changes across whole-body tracer techniques are likely due to contribution from tissues other than skeletal muscle.

The use of stable isotopically labeled tracers is a long-proven way of specifically detecting and tracking derived metabolites through a metabolic network of interest. While the recently developed stable isotope-assisted methods and associated, supporting data analysis tools have greatly improved untargeted metabolomics approaches, no software tool is currently available that allows us to automatically and flexibly search liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) chromatograms for user-definable isotopolog patterns expected for the metabolism of labeled tracer substances. Here, we present Custom Pattern Extract (CPExtract), a versatile software tool that allows for the first time the high-throughput search for user-defined isotopolog patterns in LC-HRMS data. The patterns can be specified via a set of rules including the presence or absence of certain isotopologs, their relative intensity ratios as well as chromatographic coelution. Each isotopolog pattern satisfying the respective rules is verified on an MS scan level and also in the chromatographic domain. The CPExtract algorithm allows the use of both labeled tracer compounds in nonlabeled biological samples as well as a reversed tracer approach, employing nonlabeled tracer compounds along with globally labeled biological samples. In a proof-of-concept study, we searched for metabolites specifically arising from the malonate pathway of the filamentous fungi

In mass spectrometry-based proteomics, heavy internal standards are used to validate target peptide detections and to calibrate peptide quantitation. Here, we report light contamination present in heavy labelled synthetic peptides of high isotopic enrichment. Application of such peptides as assay-internal standards potentially compromises the detection and quantitation especially of low abundant cellular peptides. Therefore, it is important to adopt guidelines to prevent false-positive identifications of endogenous light peptides as well as errors in their quantitation from biological samples.

Screening campaigns, especially those aimed at modulating enzyme activity, often rely on measuring substrate→product conversions. Unfortunately, the presence of endogenous substrates and/or products can limit one's ability to measure conversions. As well, coupled detection systems, often used to facilitate optical readouts, are subject to interference. Stable isotope labeled substrates can overcome background contamination and yield a direct readout of enzyme activity. Not only can isotope kinetic assays enable early screening, but they can also be used to follow hit progression in translational (pre)clinical studies. Herein, we consider a case study surrounding lipid biology to exemplify how metabolic flux analyses can connect stages of drug development, caveats are highlighted to ensure reliable data interpretations. For example, when measuring enzyme activity in early biochemical screening it may be enough to quantify the formation of a labeled product. In contrast, cell-based and in vivo studies must account for variable exposure to a labeled substrate (or precursor) which occurs via tracer dilution and/or isotopic exchange. Strategies are discussed to correct for these complications. We believe that measures of metabolic flux can help connect structure-activity relationships with pharmacodynamic mechanisms of action and determine whether mechanistically differentiated biophysical interactions lead to physiologically relevant outcomes. Adoption of this logic may allow research programs to (i) build a critical bridge between primary screening and (pre)clinical development, (ii) elucidate biology in parallel with screening and (iii) suggest a strategy aimed at in vivo biomarker development.

Interpretation of mercury (Hg) geochemistry in environmental systems remains a challenge. This is largely associated with the inability to identify specific Hg transformation processes and species using established analytical methods in Hg geochemistry (total Hg and Hg speciation). In this study, we demonstrate the improved Hg geochemical interpretation, particularly related to process tracing, that can be achieved when Hg stable isotope analyses are complemented by a suite of more established methods and applied to both solid- (soil) and liquid-phases (groundwater) across two Hg

Lithium is an economically important element that is increasingly extracted from brines accumulated in continental basins. While a number of studies have identified silicic magmatic rocks as the ultimate source of dissolved brine lithium, the processes by which Li is mobilized remain poorly constrained. Here we focus on the potential of low-temperature, post-eruptive processes to remove Li from volcanic glass and generate Li-rich fluids. The rhyolitic glasses in this study (from the Yellowstone-Snake River Plain volcanic province in western North America) have interacted with meteoric water emplacement as revealed by textures and a variety of geochemical and isotopic signatures. Indices of glass hydration correlate with Li concentrations, suggesting Li is lost to the water during the water-rock interaction. We estimate the original Li content upon deposition and the magnitude of Li depletion both by direct in situ glass measurements and by applying a partition-coefficient approach to plagioclase Li contents. Across our whole sample set (19 eruptive units spanning ca. 10 m.y.), Li losses average 8.9 ppm, with a maximum loss of 37.5 ppm. This allows estimation of the dense rock equivalent of silicic volcanic lithologies required to potentially source a brine deposit. Our data indicate that surficial processes occurring post-eruption may provide sufficient Li to form economic deposits. We found no relationship between deposit age and Li loss, i.e., hydration does not appear to be an ongoing process. Rather, it occurs primarily while the deposit is cooling shortly after eruption, with δ18O and δD in our case study suggesting a temperature window of 40° to 70°C.

BACKGROUND To minimize both cost and perturbations to the vitamin A system, investigators limit the amount of stable isotope administered when estimating vitamin A total body stores (TBS) by retinol isotope dilution (RID). OBJECTIVES We hypothesized that reasonable increases in the mass of stable isotope administered to theoretical subjects would have only transient impacts on vitamin A kinetics and minimal effects on RID-predicted TBS. METHODS We adapted previously-used theoretical subjects (3 children, 3 adults) with low, moderate, or high assigned TBS and applied compartmental analysis to solve a steady state model for tracer and tracee using assigned values for retinol kinetic parameters and plasma retinol. To follow retinol trafficking when increasing amounts of stable isotope were administered [1.39-7 (children) and 2.8-14 µmol retinol (adults)], we added assumptions to an established compartmental model so that plasma retinol homeostasis was maintained. Using model-simulated data, we plotted retinol kinetics versus time and applied the RID equation TBS = FaS/SAp [Fa, fraction of dose in stores; S, retinol specific activity (SA) in plasma/SA in stores; SAp, SA in plasma] to calculate vitamin A stores. RESULTS The model predicted that increasing the stable isotope dose caused transient early increases in hepatocyte total retinol; increases in plasma tracer were accompanied by decreases in tracee to maintain plasma retinol homeostasis. Despite changes in kinetic responses, RID accurately predicted assigned TBS (98-105%) at all loads for all theoretical subjects from 1-28 d postdosing. CONCLUSIONS Results indicate that, compared with doses of 1.4-3.5 µmol used in recent RID field studies, doubling the stable isotope dose should not affect accuracy of TBS predictions, thus allowing for experiments of longer duration when including a super-subject design (Ford et al., J Nutr 2020;150:411-8) and/or studying retinol kinetics.

Osmium is defined in the international council for harmonization (ICH-Q3D) guidelines as an element whose concentration can be determined by validated methods including microwave-assisted nitric acid digestion and inductively coupled plasma mass spectrometry. However, microwave digestion using nitric acid is known to result in osmium recoveries higher than the theoretical values in spiked tests because of the formation of highly volatile osmium tetroxide in an oxidation reaction. To stabilize osmium, the addition of thiourea as a complexing agent has been tested and proved its utility. It remains unclear whether other compounds can prevent the over-recovery of osmium. In this study, we investigated four compounds, thiourea, ascorbic acid, sodium sulfite, and potassium metabisulfite, that could reduce the overestimation of osmium isotopes. The minimum amounts of thiourea, ascorbic acid, sodium sulfite, and potassium metabisulfite required to stabilize 10 ng/mL osmium in blank matrix were 1.0, 1.0, 2.5, and 2.5 g/L, respectively. The relative standard deviations obtained from 12 analyses for each stabilization solution were less than 3.3% in thiourea, 12.7% in ascorbic acid, 9.0% in sodium sulfite, and 10.6% in potassium metabisulfite. The stabilization solutions were investigated in a digested tablet matrix and were found to be effective. The impact of adding stabilization solutions on the determination of all ICH-Q3D element concentrations was also evaluated. As stabilization solutions had a small or significant impact on the determination of some elements, it was concluded that osmium determination should be conducted independently.

The production of chemicals and fuels from renewable resources using engineered microbes is an attractive alternative for current fossil-dependent industries. Metabolic engineering has contributed to pathway engineering for the production of chemicals and fuels by various microorganisms. Recently, dynamic metabolic engineering harnessing synthetic biological tools has become a next-generation strategy in this field. The dynamic regulation of metabolic flux during fermentation optimizes metabolic states according to each fermentation stage such as cell growth phase and compound production phase. However, it is necessary to repeat the evaluation and redesign of the dynamic regulation system to achieve the practical use of engineered microbes. In this study, we performed quantitative metabolome analysis to investigate the effects of dynamic metabolic flux regulation on engineered Escherichia coli for γ-amino butyrate (GABA) fermentation. We prepared a stable isotope-labeled internal standard mixture (SILIS) for the stable isotope dilution method (SIDM), a mass spectrometry-based quantitative metabolome analysis method. We found multiple candidate bottlenecks for GABA production. Some metabolic reactions in the GABA production pathway should be engineered for further improvement in the direct GABA fermentation with dynamic metabolic engineering strategy.

International audience; Archaeological excavations carried out in the 1990s in the former rural parish of Rigny (Indre-et-Loire, France) uncovered 1738 graves. Among the individuals discovered, a female adult presents a series of cranial deformities characteristic of an extremely rare pathology, til then unknown in the archaeological record: the Treacher-Collins syndrome. It induces facial dysmorphism and is generally associated with hearing loss or even conductive deafness of the patient due to malformations of the hearing system.The retrospectif diagnosis of this individual was based on macroscopic analysis and computed tomography (CTscan). The use of 3D imaging made it possible to explore the impact of the pathology on the individual's hearing.In addition to the functional implications, the negative impacts of facial dysmorphic disorders in the social sphere are well known in today's societies while they are poorly documented for the medieval period.During this period, diet was an important social marker. The analysis of the individual affected by this syndrome’s diet, compared to those of other members of the Rigny village community, provide an opportunity to discuss the social significance of disability in a rural context in the Middle Ages. In this perspective, the isotopic ratios of carbon and nitrogen in this individual's bone collagen were compared to those of forty-seven other individuals found on the site.Archaeological, paleopathological and biochemical information are relevant to better characterize the functional repercussions of this syndrome on the Rigny individual and also to discuss the integration of this individual into this medieval village community.

Background The assessment of phosphate homeostasis in clinical practice relies not only on circulating phosphate levels but also on phosphate tubular reabsorption, ideally assessed using the tubular maximum phosphate reabsorption per glomerular filtration rate (TmP/GFR). TmP/GFR reference values were established before the onset of isotope-dilution mass spectrometry-standardized (IDMS) creatinine assays and thus need to be updated. Our objective is to provide reference values for TmP/GFR from childhood to adulthood, using the gold-standard of GFR assessment and IDMS-standardized creatinine values. Methods We retrospectively analysed all the inulin and iohexol clearances [measured glomerular filtration rate (mGFR)] performed in children and in adults screened for a living-donation in our unit since the beginning of IDMS-creatinine assays. TmP/GFR was calculated on a fasting sample, using the conventional formula without correction for tubular reabsorption of phosphate (TRP) in subjects below 19 years of age. Results A total of 2051 subjects (1711 children, 340 adults), aged from 1.9 to 73.4 years with normal GFR, normal phosphate and normal calcium levels, were included for TmP/GFR analysis. As expected, there was a progressive decrease along puberty in both genders of plasma phosphate and TmP/GFR, the decrease occurring earlier in girls. After the age of 19 years, there was a stabilization of plasma phosphate and TmP/GFR levels until the age of 55 years, phosphate levels and TmP/GFR being slightly lower in men than in women. Conclusion We present the largest cohort describing TmP/GFR reference values in the era of IDMS-standardized creatinine assays. We believe that these data will help physicians to better diagnose and manage patients with abnormal phosphate metabolism in daily clinical routine.

To date, subchromatin structure-based quantification of epigenetic DNA modifications is limited. Matrix attachment regions (MARs), an important subchromatin structure, contain DNA elements that specifically bind chromatin to the nuclear matrix in eukaryotes and are involved in a number of diseases. Here, we exploited a high-salt extraction-based subchromatin fractionation approach for the isolation of MAR DNA and other fractions and further developed heavy stable isotope-diluted ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) for the specific quantification of epigenetic DNA modifications in the subchromatin structures. By this approach, we showed for the first time that the content of a DNA demethylation intermediate, 5-hydroxymethylcytosine (5hmdC), in MARs decreased significantly in four tested cell lines compared to the contents in genomic DNA. In particular, the content of DNA 5hmdC in the MARs of 293T cell lines decreased the most at approximately 41.09%. Together, our findings implicate that MAR DNA is less sensitive than genomic DNA to DNA demethylation.

Kidney injury is a complication frequently encountered in hospitalized patients. Early detection of kidney injury prior to loss of renal function is an unmet clinical need that should be targeted by a protein-based biomarker panel. In this study, we aim to quantitate urinary kidney injury biomarkers at the picomolar to nanomolar level by liquid chromatography coupled to tandem mass spectrometry in multiple reaction monitoring mode (LC-MRM-MS). Proteins were immunocaptured from urinary samples, denatured, reduced, alkylated, and digested into peptides before LC-MRM-MS analysis. Stable-isotope-labeled peptides functioned as internal standards, and biomarker concentrations were attained by an external calibration strategy. The method was evaluated for selectivity, carryover, matrix effects, linearity, and imprecision. The LC-MRM-MS method enabled the quantitation of KIM-1, NGAL, TIMP2, IGFBP7, CXCL9, nephrin, and SLC22A2 and the detection of TGF-β1, cubilin, and uromodulin. Two to three peptides were included per protein, and three transitions were monitored per peptide for analytical selectivity. The analytical carryover was

The implementation of high-resolution mass spectrometry systems offers new possibilities for the analysis of complex art samples such as historical oil paintings. However, these multicomponent systems generate large and complex data sets that require advanced visualization tools to aid interpretation, especially when no chromatographic separation is performed. In the context of this research, it was crucial to propose a data analysis tool to identify the products generated during the synthesis, drying, and aging of historical pigments. This study reports for the first time a nontraditional mass defect analysis of oil paint samples containing a fugitive brominated-organic pigment, eosin or geranium lake, by using direct infusion electrospray ionization in combination with a high-resolution Orbitrap mass spectrometer. The use of nontraditional Kendrick mass defect plots is presented in this study as a processing and visualization tool to recognize brominated species based on their specific mass defect and isotope pattern. The results demonstrate that this approach could provide valuable molecular compositional information on the degradation pathways of this pigment. We anticipate that mass defect analysis will become highly relevant in future degradation studies of many more historical organic pigments.