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1.
Food Chem ; 313: 126093, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31927205

RESUMO

Multivariate stable isotope analysis combined with chemometrics was used to investigate and discriminate rice samples from six rice producing provinces in China (Heilongjiang, Jilin, Jiangsu, Zhejiang, Hunan and Guizhou) and four other Asian rice producing countries (Thailand, Malaysia, Philippines, and Pakistan). The stable isotope characteristics were analyzed for rice of different species cultivated with varied farming methods at different altitudes and latitudes/longitudes. The index groups of δ13C, δ15N, δ18O, 207/206Pb and 208/207Pb were screened and established for the selected samples with different geographical features by means of principal component analysis (PCA) and discriminant analysis (DA), which would provide a sound technical solution for rice traceability and serve as a template for further research on the traceability of other agricultural products, especially plant-derived products.


Assuntos
Marcação por Isótopo , Oryza/química , Isótopos de Carbono/análise , China , Análise Discriminante , Isótopos/análise , Chumbo/análise , Malásia , Espectrometria de Massas , Isótopos de Nitrogênio/análise , Oryza/metabolismo , Paquistão , Filipinas , Análise de Componente Principal , Tailândia
2.
J Agric Food Chem ; 68(6): 1678-1683, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31957422

RESUMO

During submerged cultivation, the edible basidiomycete Fomitopsis betulina (previously Piptoporus betulinus) developed a fruity odor, strongly reminding of pineapple. Olfactometric analysis showed that this impression was mainly caused by the two (5E/Z,7E,9)-decatrien-2-ones. At the time of maximum concentration on the 5th day, the (5E/5Z)-ratio was 94:6. Three hypotheses were experimentally examined to shed light onto the genesis of the uncommon volatiles: first, an indirect effect of agro-industrial side-streams, such as cabbage cuttings, supporting good growth; second, an unsaturated odd-numbered fatty acid precursor; and third, a polyketide-like pathway. In the presence of 1-13C- or 2-13C-acetate up to five acetates were incorporated into the molecular ions of the C10-body. Addition of 1-13C-pyruvate or 1-13C-lactate did not confirm an odd-numbered starter of the polyketide chain. None of the methylketones was found in pineapple or any other food before.


Assuntos
Coriolaceae/química , Odorantes/análise , Compostos Orgânicos Voláteis/química , Acetatos/análise , Isótopos de Carbono/análise , Coriolaceae/crescimento & desenvolvimento , Coriolaceae/metabolismo , Cetonas/química , Compostos Orgânicos Voláteis/metabolismo
3.
J Agric Food Chem ; 68(5): 1213-1225, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31903748

RESUMO

Organically farmed rice is believed to be healthier, safer, and eco-friendlier than its conventionally farmed counterparts and sells for a premium price in global markets. Deliberate mislabeling of organic rice has become a critical consumer concern in China and elsewhere, and there is an increased risk of buying fraudulent organic rice in the market place. In this study, stable isotopic and multielemental analysis combined with chemometrics was used to differentiate organically farmed rice from green and conventional rice in a 4-year experimental field trial from 2014 to 2017. A total of 108 rice samples and their associated soils were collected during the study from three farming (fertilization) systems to investigate whether there are long-term changes in the rice farming classification accuracy from climate effects. Stable carbon and nitrogen isotopic ratios (i.e., δ13C and δ15N) and 27 elemental contents (e.g., Na, K, Ca, Fe, and Zn) of rice and soil samples were determined and then evaluated using statistical analysis [i.e., one-way analysis of variance, multivariable correlation analysis, and modeling of partial least-squares discriminant analysis]. Although δ15N values can be an effective indicator for organic rice authentication during one crop rotation, both δ13C and δ15N values of rice were easily affected by rice cultivar and interannual soil fertilization and localized agroclimatic variations. These two isotopes were not able to separate organic rice from green and conventional rice accurately. Elemental contents of green and conventional rice (especially K and Ca) were found at higher levels due to the abundant application of synthetic fertilizers (e.g., KNO3, KH2PO4, and CaHPO4), unlike organically farmed rice, which primarily used animal manure and composts. Partial least-squares discriminant analysis modeling combined isotopic and elemental signatures to correctly differentiate organic rice from green and conventional counterparts, with an accuracy up to 100% over the 4-year study. Therefore, this multi-isotope and -element strategy proposes a more rigorous, alternative tool to combat fraudulent mislabeling of organic rice, increasing the trust of organically labeled rice products and supporting the integrity of the organic sector worldwide.


Assuntos
Isótopos de Carbono/análise , Contaminação de Alimentos/análise , Alimentos Orgânicos/análise , Isótopos de Nitrogênio/análise , Oryza/química , Oligoelementos/análise , China , Análise Discriminante , Fertilizantes/análise , Oryza/classificação , Solo/química
4.
Chemosphere ; 242: 125130, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31669996

RESUMO

Identifying co-metabolic TCE oxidation in polluted groundwater is challenging due to lack of indicative by-products. This challenge may theoretically be resolved if the oxidation process can be characterized by a distinct dual isotope enrichment. In this work, we aimed to explore the carbon and chlorine isotope effects associated with TCE oxidation by a variety of oxygenases. These included pure strains and enrichment cultures of methane, toluene and ammonia oxidizers, as well as experiments with crude extracts. Isotope effects determined for TCE oxidation by toluene and ammonia oxidizers were mostly in line with expected values for epoxidation mechanism (ϵ13C -11.0 ±â€¯0.7 to -24.8 ±â€¯0.2‰ and ϵ37Cl +0.9 ± 0.5 to +1.0 ± 0.4‰), whereas, the methanotrophs resulted in distinctively different isotope effects (ϵ13C -2.4 ±â€¯0.4 to -3.4 ±â€¯0.8‰ and ϵ37Cl -1.8 ±â€¯0.2 to -2.9 ±â€¯0.9‰). It is suggested that in TCE oxidation by methanotrophs, substrate binding rather than bond cleavage is rate limiting, leading to this unexpected isotope effect. On the environmental level, our results imply that the oxidative process can be differentiated if catalyzed by toluene and ammonia oxidizers or by methanotrophs. Additionally, the oxidative process can be distinguished from the reductive one. However, using dual isotope analysis in the field may result in an under-estimation of the overall co-metabolic process if methanotrophs are to be excluded due to low isotope effects.


Assuntos
Biodegradação Ambiental , Cloro/metabolismo , Tricloroetileno/metabolismo , Poluentes Químicos da Água/metabolismo , Carbono , Isótopos de Carbono/análise , Respiração Celular , Fracionamento Químico , Cloro/química , Poluição Ambiental/análise , Água Subterrânea/química , Metano , Tricloroetileno/química , Poluentes Químicos da Água/química
5.
J Sci Food Agric ; 100(4): 1625-1634, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31802505

RESUMO

BACKGROUND: Walnuts (Juglans regia L.) are considered of high value for human nutrition and are cultivated worldwide. With globalization, however, the demand for regional products has increased. Isotopic fingerprints (δ2 H-, δ15 N- and δ13 C-values (‰)) created by means of stable isotope ratio mass spectrometry provide the possibility of tracing the geographical provenance of plant foods. RESULTS: Authentic walnut samples from different geographical regions in Germany could be separated from each other by means of their bulk δ2 H-values (‰) with samples from northern regions being more enriched in 2 H than samples collected from southern Germany. Next to precipitation data, the topography of the surrounding landscape of the sampling sites was taken into account for data interpretation by the creation of approximate elevation profiles. Moreover, German walnuts could be separated from French walnuts which showed significantly higher δ2 H-values (‰). Variations in annual total precipitation was reflected by the shift in δ2 H-ranges (‰) depending on the harvesting year. Additionally, organic walnuts could be well separated from conventionally produced walnuts due to their distinct δ15 N-values (‰) which could be ascribed to a cultivation practice common for organic farming. CONCLUSIONS: The data presented here outlined the potential of determining isotopic fingerprints of walnuts from different sites within one country for tracing their regional origin and revealing their cultivation conditions. Including topographic characteristics between the sampling locations as well as precipitation data helped to even differentiate walnuts from two adjoining countries. © 2019 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Isótopos de Carbono/análise , Deutério/análise , Juglans/química , Isótopos de Nitrogênio/análise , Análise Discriminante , Alemanha , Espectrometria de Massas , Nozes/química
6.
Sci Total Environ ; 704: 135461, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31810680

RESUMO

Stable carbon isotope ratios (δ13C) are widely used as climate proxies for assessing and predicting climatic information at an annual resolution. However, the detailed information in the isotopes that results from intra-annual climate scenarios and is associated with mineral accumulation remains unclear. Combined with investigations of elements and ash contents, variations in foliar δ13C in relation to annual, winter and summer climate scenarios were investigated in a dendroclimatologically important tree species Sabina przewalskii Kom. Foliar δ13C exhibited a significant negative correlation with mean annual temperature, mean annual precipitation and mean annual relative humidity as well as significant positive correlations with elevation. Climatic factors in winter and summer have opposite effects on the variation of δ13C. The beneficial mineral element Si had a significant positive correlation with foliar δ13C, whereas the essential mineral elements K, Ca, and Mg did not. Specifically, Si and δ13C have similar correlations with climate factors and elevation. These results suggest that measurement of Si content has a similar potential to δ13C for use as an alternative climate indicator when detailed climatic information may otherwise be limited and provide a basis for understanding the integration of δ13C in plant responses to climate.


Assuntos
Clima , Monitoramento Ambiental , Silício/análise , Isótopos de Carbono/análise , Folhas de Planta/química , Tibet , Árvores
7.
J Sci Food Agric ; 100(3): 995-1003, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31646635

RESUMO

BACKGROUND: New techniques are required to guarantee the authenticity of food, especially for PDO (Protected Designation of Origin) trademarks. The genuineness of a product is directly related to the raw material and to the production process used. In this article, the traceability of the Mozzarella di Bufala Campana PDO was investigated, using carbon, nitrogen and oxygen stable isotopes ratios, measured on buffalo feeding, milk and mozzarella, from Caserta and Salerno farms. Furthermore, 37 mozzarella brands were analyzed (carbon, nitrogen and oxygen isotopes) from the different production areas, to characterize their origin. RESULTS: The results of this work showed no changes in carbon and nitrogen isotopic ratios of milk and mozzarella, indicating no fractionation in the production process. The δ13 C of milk was influenced by feeding signal; while, milk δ15 N was regulated by fractionation occurring during ruminant metabolism. Mozzarella oxygen isotopic signal depleted with respect to the milk one. Regarding brand samples, it was found that the geographical differentiation is based more on carbon isotopes than on the nitrogen and oxygen ones. CONCLUSION: This work gives an important contribution to the knowledge regarding the traceability of such a particular cheese as mozzarella. © 2019 Society of Chemical Industry.


Assuntos
Isótopos de Carbono/análise , Queijo/análise , Contaminação de Alimentos/análise , Isótopos de Nitrogênio/análise , Isótopos de Oxigênio/análise , Ração Animal/análise , Animais , Búfalos/metabolismo , Leite/química , Leite/metabolismo
8.
Environ Pollut ; 256: 113401, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753639

RESUMO

This study reveals the impact of biomass burning (BB) on secondary organic aerosols (SOA) formation in the North China Plain (NCP). Filter samples were analyzed for secondary inorganic aerosols (SIA), oxalic acid (C2) and related aqueous-phase SOA compounds (aqSOA), stable carbon isotope composition of C2 (δ13C(C2)) and aerosol liquid water content (ALWC). Based on the PM2.5 loadings, BB tracer concentrations, wildfire spots and air-mass back trajectories, we distinguished two episodes from the whole campaign, Episode I and Episode II, which were characteristic of regional and local BB, respectively. The abundances of PM2.5 and organic matter in the two events were comparable, but concentrations and fractions of SIA, aqSOA during Episode I were much higher than those during Episode II, along with heavier δ13C(C2), suggesting an enhanced aqSOA formation in the earlier period. We found that the enhancement of aqSOA formation during Episode I was caused by an increased ALWC, which was mainly driven by SIA during the regional BB event. Our work showed that intensive burning of crop residue in East Asia can sharply enhance aqSOA production on a large scale, which may have a significant impact on the regional climate and human health.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Monitoramento Ambiental , Biomassa , Carbono/análise , Isótopos de Carbono/análise , China , Clima , Extremo Oriente , Compostos Orgânicos/análise , Material Particulado/análise , Estações do Ano , Água , Incêndios Florestais
9.
J Plant Physiol ; 243: 153056, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31704533

RESUMO

Plant wax n-alkanes are a major constituent of the leaf and grain surface. In this study, we explored what can be learned from the abundance and carbon isotopic composition (δ13C) of n-alkanes in historical winter wheat cultivars. We investigated leaf and grain wax n-alkane concentration (ΣalkLand ΣalkG) and carbon isotopes (δ13CalkL and δ13CalkG) on C29 as well as bulk leaf and grain carbon isotopes (δ13CbulkL and δ13CbulkG) to assess if these wax components changed across five wheat cultivars released from the 1950s to the early 2010s. Results showed that ΣalkL and grain yield increased, while δ13CalkL and δ13CbulkL decreased across the historical wheat cultivars. We found a significant correlation between ΣalkL and shoot biomass at the early growth stage, and a strong correlation between ΣalkL at the grain-filling stage and grain yield. Grain measures, including ΣalkG, δ13CalkG, and δ13CbulkG did not correlate with crop production. Although δ13CalkL and grain yield were not correlated at the flowering stage, they were correlated at the grain-filling stage under dry conditions. Our results indicate that increased ΣalkL has been indirectly selected in breeding efforts to improve crop production in winter wheat, suggesting that greater leaf waxiness confers advantages for crop growth.


Assuntos
Alcanos/metabolismo , Melhoramento Vegetal , Folhas de Planta/fisiologia , Triticum/fisiologia , Isótopos de Carbono/análise , Produtos Agrícolas , Folhas de Planta/genética , Triticum/genética , Triticum/crescimento & desenvolvimento , Ceras/metabolismo
10.
Environ Int ; 133(Pt B): 105235, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31675570

RESUMO

Pathogens are known to survive in compost and to regrow under the influence of certain factors, such as moisture content, temperature and nutrient availability. Dead biomass, by providing available nutrients, is a factor that may affect pathogen regrowth. However, the indigenous microorganisms, including pathogens, that grown on the dead biomass of compost have not yet been identified. Here, the regrowth potential of the pathogenic indicator bacterium Escherichia coli in the presence of dead bacterial biomass was determined, and the biomass metabolizers that grew competitively with E. coli were identified by high-sensitivity stable isotope probing of rRNA. Culture-dependent analysis indicated that the addition of dead bacterial biomass did not stimulate E. coli growth. High-throughput analysis of density-resolved 16S rRNA molecules from compost samples amended with carbon-13-labeled dead bacterial biomass revealed dead bacterial-assimilating bacteria, including Sphingobium sp., myxobacterial lineages and Bacillales. These bacteria are potentially competitive with pathogens due to their preferential assimilation of dead biomass in compost.


Assuntos
Bactérias/metabolismo , Biomassa , Marcação por Isótopo/métodos , Microbiologia do Solo , Isótopos de Carbono/análise , Isótopos de Carbono/metabolismo , Compostagem , Escherichia coli/metabolismo , Consórcios Microbianos
11.
J Plant Physiol ; 243: 153052, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31689580

RESUMO

Sweet potato (Ipomoea batatas L.) is an important crop in the world, cultivated in temperate climates under low inputs. Drought changes the plant biomass allocation, together with the carbon and nitrogen isotopic composition (δ13C and δ15N), whose changes are faintly known in sweet potato crops. Here, we show the biomass allocation of eight sweet potato accessions submitted to drought during 3 months, using the δ13C, δ15N, carbon isotope discrimination (Δ13C), total carbon (TC) and water use efficiency (WUE) traits. The tolerant accessions had improved WUE, with higher TPB and TC. Storage roots and shoots had a heavier δ13C content under drought stress, with greater 13C fixation in roots. The Δ13C did not show a significant association with WUE. The δ15N values indicated a generalised N reallocation between whole-plant organs under drought, as a physiological integrator of response to environmental stress. This information can aid the selection of traits to be used in sweet potato breeding programs, to adapt this crop to climate change.


Assuntos
Biomassa , Isótopos de Carbono/análise , Carbono/metabolismo , Secas , Ipomoea batatas/fisiologia , Radioisótopos de Nitrogênio/análise
12.
BMC Bioinformatics ; 20(1): 524, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31660850

RESUMO

BACKGROUND: Stable isotope tracing can follow individual atoms through metabolic transformations through the detection of the incorporation of stable isotope within metabolites. This resulting data can be interpreted in terms related to metabolic flux. However, detection of a stable isotope in metabolites by mass spectrometry produces a profile of isotopologue peaks that requires deconvolution to ascertain the localization of isotope incorporation. RESULTS: To aid the interpretation of the mass spectroscopy isotopologue profile, we have developed a moiety modeling framework for deconvoluting metabolite isotopologue profiles involving single and multiple isotope tracers. This moiety modeling framework provides facilities for moiety model representation, moiety model optimization, and moiety model selection. The moiety_modeling package was developed from the idea of metabolite decomposition into moiety units based on metabolic transformations, i.e. a moiety model. The SAGA-optimize package, solving a boundary-value inverse problem through a combined simulated annealing and genetic algorithm, was developed for model optimization. Additional optimization methods from the Python scipy library are utilized as well. Several forms of the Akaike information criterion and Bayesian information criterion are provided for selecting between moiety models. Moiety models and associated isotopologue data are defined in a JSONized format. By testing the moiety modeling framework on the timecourses of 13C isotopologue data for uridine diphosphate N-acetyl-D-glucosamine (UDP-GlcNAc) in human prostate cancer LnCaP-LN3 cells, we were able to confirm its robust performance in isotopologue deconvolution and moiety model selection. CONCLUSIONS: SAGA-optimize is a useful Python package for solving boundary-value inverse problems, and the moiety_modeling package is an easy-to-use tool for mass spectroscopy isotopologue profile deconvolution involving single and multiple isotope tracers. Both packages are freely available on GitHub and via the Python Package Index.


Assuntos
Metabolômica , Teorema de Bayes , Isótopos de Carbono/análise , Linhagem Celular Tumoral , Humanos , Marcação por Isótopo , Masculino , Espectrometria de Massas/métodos , Metabolômica/métodos , Neoplasias da Próstata
13.
Isotopes Environ Health Stud ; 55(6): 588-606, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31648560

RESUMO

A novel doubly [1-13C, α-15NH2]-labelled amino acid method (DLAAM) is presented for the determination of the CO2 production (RCO2) and energy expenditure in humans. This method is based on the simultaneous administration of [1-13C]glycine and [15N]glycine followed by the measurement of excretion kinetics of breath 13CO2 and urinary 15N. The basic idea of the DLAAM is that the unknown 13C recovery RF(13C) of the 1-13C amino acid, essential for the calculation of the net CO2 production, can be approximated by the easily measureable 15N recovery RF(15N) of the α-15NH2 labelled amino acid. In four healthy adult men (76-97 kg) the DLAAM was tested parallel to the IC and in one man (74 kg) parallel to the DLWM. Using the approximation RF(13C) ≈ RF(15N) the RCO2 (in l CO2 d-1) was calculated to 387.0 ± 30.3 (DLAAM) vs. 382.8 ± 22.6. (IC). The Bland-Altman plot shows that the difference between the DLAAM and IC of individual RCO2 is within the 95 % confidence interval (mean ± 2 SD): +4.3 ± 37.5 l CO2 d-1. We conclude that the DLAAM and IC may be used interchangeably. The physical activity level (PAL) was calculated based on the DLAAM vs. DLWM to about 1.5.


Assuntos
Aminoácidos/química , Dióxido de Carbono/análise , Isótopos de Carbono/análise , Metabolismo Energético/fisiologia , Isótopos de Nitrogênio/análise , Proteínas/metabolismo , Adulto , Testes Respiratórios , Calorimetria Indireta , Humanos , Cinética , Masculino , Adulto Jovem
14.
Isotopes Environ Health Stud ; 55(6): 526-531, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31597451

RESUMO

Drying protocols might alter the isotopic signatures of plant samples given that high temperatures can volatilize various organic compounds or delay the halting of physiological processes at lower drying temperatures. We thus evaluated the effect of four drying protocols on the carbon and nitrogen isotopic signatures for 23 species of plants. In particular, leaves were either freeze-dried, placed in a herbarium drying stove (ca. 50°C), in a gravity convection oven (80°C), or microwaved (900 W) in 2-minute pulses, until constant weight. For each species, neither treatment led to significantly different δ13C values, which ranged from -31.7 to -12.4‰. The δ15N values of 21 of the species considered were not affected by the drying protocols, ranging from -11.6 to -8.8‰. For Tillandsia makoyana, significant differences were observed between the freeze dried and the microwaved samples and between the freeze dried samples and those dried at 50°C for Macroptilium gibbosifolium.


Assuntos
Isótopos de Carbono/análise , Dessecação/métodos , Monitoramento Ambiental/métodos , Liofilização , Isótopos de Nitrogênio/análise , Folhas de Planta/química , Fabaceae/química , Temperatura Alta , Inquéritos e Questionários , Volatilização
15.
Environ Int ; 133(Pt A): 105166, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31518928

RESUMO

Sedimentary organic matters in the typical intertidal areas were investigated to address year-round monthly distributions and site-specific sources. Target areas included four natural tidal flats (Ganghwa, Garolim, Sinan, and Suncheon) and one artificially closed estuary (Nakdong River), South Korea (in 2018). Among the parameters monitored, mud content was a key factor controlling organic matter contents, across varying habitats, with significant positive correlations to total organic carbon (TOC, r = 0.66, p < 0.001) and total nitrogen (TN, r = 0.44, p < 0.001). The elevated TOC and TN contents and heavier carbon stable isotope ratios (δ13C) in sediments of Garolim and Suncheon from February to April reflected the winter microphytobenthos blooms, receiving prevailed marine sources. Whilst, the depleted δ13C and δ15N values in sediments of Nakdong River estuary were observed during flood season (September-October), indicating direct influence of terrestrial organic input through freshwater discharge. Overall, distributions and sources of sedimentary organic matters in the Korean coastal waters suggested variabilities in season and space, with anthropogenic alteration. The data accumulated in this study would provide baseline information for sediment organic carbon stocks in the Korean coastal waters and elsewhere.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Compostos Orgânicos/análise , Carbono/análise , Isótopos de Carbono/análise , Ecossistema , Água Doce , Nitrogênio/análise , Isótopos de Nitrogênio/análise , República da Coreia , Rios
16.
Environ Sci Pollut Res Int ; 26(32): 33023-33029, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31512132

RESUMO

The goals of this study were to analyze if there is a difference in the stable isotopic ratio (δ13C and δ15N) of macrobenthic species sampled at two sandy beaches (one close to a river mouth and the other far from any freshwater input) and to identify differences in the stable isotopic ratio (δ13C and δ15N) in different body parts of three representative species of two Brazilian sandy beach macrofaunas: the polychaete Hemipodia californiensis, the mollusk bivalve Donax hanleyanus, and the crustacean decapod Emerita brasiliensis. No significant differences were detected in the δ13C stable isotopic ratio between the two sites analyzed; however, in the δ15N stable isotopic ratio, a significant difference was observed. Regarding the intraspecific response of stable isotopic ratio, D. hanleyanus showed a significant difference in carbon among different body part structures, while a trend for significance was observed for nitrogen isotopes. The differences were significant for both isotopes in E. brasiliensis, and no differences were observed among the body part structures in H. californiensis. There were significant differences in E. brasiliensis carapaces with regard to the δ15N stable isotopic ratio between the muscle and the whole body. Although the δ13C and δ15N stable isotopic ratio differs significantly in the digestive tract, muscles, and whole body of D. hanleyanus, such differences were not enough to determine changes in their trophic levels and food sources. Similar stable isotopic ratios were observed in the whole body, proboscis, and teeth of H. californiensis, highlighting this species as the top predator. In conclusion, stable isotopic analysis of benthic trophic structure can be employed as a tool in coastal management plans or environmental impact studies.


Assuntos
Monitoramento Ambiental , Poluentes da Água/análise , Animais , Praias , Bivalves , Brasil , Carbono/análise , Isótopos de Carbono/análise , Cadeia Alimentar , Isótopos de Nitrogênio/análise , Nutrientes , Rios
17.
Artigo em Inglês | MEDLINE | ID: mdl-31540022

RESUMO

Dissolved inorganic carbon isotope composition (δ13CDIC), together with major ion concentrations were measured in the Mun River and its tributaries in March 2018 to constrain the origins and cycling of dissolved inorganic carbon. In the surface water samples, the DIC content ranged from 185 to 5897 µmol/L (average of 1376 µmol/L), and the δ13CDIC of surface water ranged from -19.6‱ to -2.7‱. In spite of the high variability in DIC concentrations and partial pressure of carbon dioxide (pCO2), the δ13CDIC values of the groundwater were relatively consistent, with a mean value of -16.9 ± 1.4‱ (n = 9). Spatial changes occurred in the direction and magnitude of CO2 flux through water-air interface (FCO2). In the dry season, fluxes varied from -6 to 1826 mmol/(m2·d) with an average of 240 mmol/(m2·d). In addition to the dominant control on hydrochemistry and dissolved inorganic carbon isotope composition by the rock weathering, the impacts from anthropogenic activities were also observed in the Mun River, especially higher DIC concentration of waste water from urban activities. These human disturbances may affect the accurate estimate contributions of carbon dioxide from tropical rivers to the atmospheric carbon budgets.


Assuntos
Ciclo do Carbono , Carbono/análise , Rios/química , Agricultura , Dióxido de Carbono/análise , Isótopos de Carbono/análise , Água Subterrânea/química , Estações do Ano , Tailândia
18.
Nature ; 574(7777): 242-245, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31554971

RESUMO

The Chicxulub bolide impact 66 million years ago drove the near-instantaneous collapse of ocean ecosystems. The devastating loss of diversity at the base of ocean food webs probably triggered cascading extinctions across all trophic levels1-3 and caused severe disruption of the biogeochemical functions of the ocean, and especially disrupted the cycling of carbon between the surface and deep sea4,5. The absence of sufficiently detailed biotic data that span the post-extinction interval has limited our understanding of how ecosystem resilience and biochemical function was restored; estimates6-8 of ecosystem 'recovery' vary from less than 100 years to 10 million years. Here, using a 13-million-year-long nannoplankton time series, we show that post-extinction communities exhibited 1.8 million years of exceptional volatility before a more stable equilibrium-state community emerged that displayed hallmarks of resilience. The transition to this new equilibrium-state community with a broader spectrum of cell sizes coincides with indicators of carbon-cycle restoration and a fully functioning biological pump9. These findings suggest a fundamental link between ecosystem recovery and biogeochemical cycling over timescales that are longer than those suggested by proxies of export production7,8, but far shorter than the return of taxonomic richness6. The fact that species richness remained low as both community stability and biological pump efficiency re-emerged suggests that ecological functions rather than the number of species are more important to community resilience and biochemical functions.


Assuntos
Aclimatação , Biodiversidade , Ecossistema , Extinção Biológica , Animais , Isótopos de Carbono/análise , Cadeia Alimentar , Fósseis , História Antiga , Plâncton/classificação , Plâncton/isolamento & purificação
19.
Nat Protoc ; 14(10): 2856-2877, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31471597

RESUMO

Precise quantification of metabolic pathway fluxes in biological systems is of major importance in guiding efforts in metabolic engineering, biotechnology, microbiology, human health, and cell culture. 13C metabolic flux analysis (13C-MFA) is the predominant technique used for determining intracellular fluxes. Here, we present a protocol for 13C-MFA that incorporates recent advances in parallel labeling experiments, isotopic labeling measurements, and statistical analysis, as well as best practices developed through decades of experience. Experimental design to ensure that fluxes are estimated with the highest precision is an integral part of the protocol. The protocol is based on growing microbes in two (or more) parallel cultures with 13C-labeled glucose tracers, followed by gas chromatography-mass spectrometry (GC-MS) measurements of isotopic labeling of protein-bound amino acids, glycogen-bound glucose, and RNA-bound ribose. Fluxes are then estimated using software for 13C-MFA, such as Metran, followed by comprehensive statistical analysis to determine the goodness of fit and calculate confidence intervals of fluxes. The presented protocol can be completed in 4 d and quantifies metabolic fluxes with a standard deviation of ≤2%, a substantial improvement over previous implementations. The presented protocol is exemplified using an Escherichia coli ΔtpiA case study with full supporting data, providing a hands-on opportunity to step through a complex troubleshooting scenario. Although applications to prokaryotic microbial systems are emphasized, this protocol can be easily adjusted for application to eukaryotic organisms.


Assuntos
Isótopos de Carbono/análise , Escherichia coli/metabolismo , Cromatografia Gasosa-Espectrometria de Massas/métodos , Marcação por Isótopo/métodos , Metabolômica/métodos , Isótopos de Carbono/metabolismo , Cromatografia Gasosa-Espectrometria de Massas/instrumentação , Glucose/metabolismo , Modelos Biológicos , Software , Fluxo de Trabalho
20.
Ann Hum Biol ; 46(5): 378-387, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31475587

RESUMO

Background: The population of Roman Britain are renowned for having elevated nitrogen (δ15) stable isotope values, which have been interpreted as evidence for the increased consumption of marine products. However, such results are now understood to also reflect episodes of stress and disease, suggesting that new interpretations are warranted.Aim: To test a novel approach which combines hazard mortality analysis and stable isotope data to determine whether there is a relationship between age-at-death, elevated δ15N values and mortality risk.Subjects and methods: This study used published osteological and dietary stable isotope data for nitrogen (δ15N) and carbon (δ13C) of 659 1st-5th century AD individuals aged >12 years old excavated from Roman cemeteries in Britain. The relationship between diet and mortality risk was assessed using the Gompertz hazard model, and differences in median reported isotope values between the sexes was determined using a Mann Whitney test.Results: It was discovered that higher δ15N levels are associated with elevated risks of mortality, whereas the opposite pattern was observed for δ13C, and males had higher median δ13C and δ15N values.Conclusion: This study successfully demonstrated that stable isotope data can be integrated into hazard models, allowing one to connect diet and mortality in past populations. It supports the findings of other isotope studies which have established that individuals with childhood stress/trauma will have different isotope patterns.


Assuntos
Dieta/estatística & dados numéricos , Análise de Alimentos , Mortalidade , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Isótopos de Carbono/análise , Inglaterra/epidemiologia , Feminino , História Antiga , Humanos , Masculino , Pessoa de Meia-Idade , Isótopos de Nitrogênio/análise , Modelos de Riscos Proporcionais , Fatores Sexuais , Adulto Jovem
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