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1.
Nature ; 555(7695): 223-226, 2018 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-29516995

RESUMEN

The depth to which Jupiter's observed east-west jet streams extend has been a long-standing question. Resolving this puzzle has been a primary goal for the Juno spacecraft, which has been in orbit around the gas giant since July 2016. Juno's gravitational measurements have revealed that Jupiter's gravitational field is north-south asymmetric, which is a signature of the planet's atmospheric and interior flows. Here we report that the measured odd gravitational harmonics J3, J5, J7 and J9 indicate that the observed jet streams, as they appear at the cloud level, extend down to depths of thousands of kilometres beneath the cloud level, probably to the region of magnetic dissipation at a depth of about 3,000 kilometres. By inverting the measured gravity values into a wind field, we calculate the most likely vertical profile of the deep atmospheric and interior flow, and the latitudinal dependence of its depth. Furthermore, the even gravity harmonics J8 and J10 resulting from this flow profile also match the measurements, when taking into account the contribution of the interior structure. These results indicate that the mass of the dynamical atmosphere is about one per cent of Jupiter's total mass.

2.
Nature ; 555(7695): 227-230, 2018 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-29517000

RESUMEN

Jupiter's atmosphere is rotating differentially, with zones and belts rotating at speeds that differ by up to 100 metres per second. Whether this is also true of the gas giant's interior has been unknown, limiting our ability to probe the structure and composition of the planet. The discovery by the Juno spacecraft that Jupiter's gravity field is north-south asymmetric and the determination of its non-zero odd gravitational harmonics J3, J5, J7 and J9 demonstrates that the observed zonal cloud flow must persist to a depth of about 3,000 kilometres from the cloud tops. Here we report an analysis of Jupiter's even gravitational harmonics J4, J6, J8 and J10 as observed by Juno and compared to the predictions of interior models. We find that the deep interior of the planet rotates nearly as a rigid body, with differential rotation decreasing by at least an order of magnitude compared to the atmosphere. Moreover, we find that the atmospheric zonal flow extends to more than 2,000 kilometres and to less than 3,500 kilometres, making it fully consistent with the constraints obtained independently from the odd gravitational harmonics. This depth corresponds to the point at which the electric conductivity becomes large and magnetic drag should suppress differential rotation. Given that electric conductivity is dependent on planetary mass, we expect the outer, differentially rotating region to be at least three times deeper in Saturn and to be shallower in massive giant planets and brown dwarfs.

3.
Nature ; 555(7695): 220-222, 2018 03 07.
Artículo en Inglés | MEDLINE | ID: mdl-29517001

RESUMEN

The gravity harmonics of a fluid, rotating planet can be decomposed into static components arising from solid-body rotation and dynamic components arising from flows. In the absence of internal dynamics, the gravity field is axially and hemispherically symmetric and is dominated by even zonal gravity harmonics J2n that are approximately proportional to qn, where q is the ratio between centrifugal acceleration and gravity at the planet's equator. Any asymmetry in the gravity field is attributed to differential rotation and deep atmospheric flows. The odd harmonics, J3, J5, J7, J9 and higher, are a measure of the depth of the winds in the different zones of the atmosphere. Here we report measurements of Jupiter's gravity harmonics (both even and odd) through precise Doppler tracking of the Juno spacecraft in its polar orbit around Jupiter. We find a north-south asymmetry, which is a signature of atmospheric and interior flows. Analysis of the harmonics, described in two accompanying papers, provides the vertical profile of the winds and precise constraints for the depth of Jupiter's dynamical atmosphere.

4.
Ann Oncol ; 34(7): 578-588, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37100205

RESUMEN

BACKGROUND: We aim to implement an immune cell score model in routine clinical practice for resected non-small-cell lung cancer (NSCLC) patients (NCT03299478). Molecular and genomic features associated with immune phenotypes in NSCLC have not been explored in detail. PATIENTS AND METHODS: We developed a machine learning (ML)-based model to classify tumors into one of three categories: inflamed, altered, and desert, based on the spatial distribution of CD8+ T cells in two prospective (n = 453; TNM-I trial) and retrospective (n = 481) stage I-IIIA NSCLC surgical cohorts. NanoString assays and targeted gene panel sequencing were used to evaluate the association of gene expression and mutations with immune phenotypes. RESULTS: Among the total of 934 patients, 24.4% of tumors were classified as inflamed, 51.3% as altered, and 24.3% as desert. There were significant associations between ML-derived immune phenotypes and adaptive immunity gene expression signatures. We identified a strong association of the nuclear factor-κB pathway and CD8+ T-cell exclusion through a positive enrichment in the desert phenotype. KEAP1 [odds ratio (OR) 0.27, Q = 0.02] and STK11 (OR 0.39, Q = 0.04) were significantly co-mutated in non-inflamed lung adenocarcinoma (LUAD) compared to the inflamed phenotype. In the retrospective cohort, the inflamed phenotype was an independent prognostic factor for prolonged disease-specific survival and time to recurrence (hazard ratio 0.61, P = 0.01 and 0.65, P = 0.02, respectively). CONCLUSIONS: ML-based immune phenotyping by spatial distribution of T cells in resected NSCLC is able to identify patients at greater risk of disease recurrence after surgical resection. LUADs with concurrent KEAP1 and STK11 mutations are enriched for altered and desert immune phenotypes.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas , Neoplasias Pulmonares , Humanos , Carcinoma de Pulmón de Células no Pequeñas/genética , Carcinoma de Pulmón de Células no Pequeñas/cirugía , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/cirugía , Estudios Retrospectivos , Proteína 1 Asociada A ECH Tipo Kelch/genética , Estudios Prospectivos , Factor 2 Relacionado con NF-E2/genética , Factor 2 Relacionado con NF-E2/metabolismo , Recurrencia Local de Neoplasia , Pronóstico , Fenotipo , Mutación , Quinasas de la Proteína-Quinasa Activada por el AMP
5.
Geophys Res Lett ; 49(20): e2022GL099529, 2022 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-36582355

RESUMEN

The climate signal imprinted in the snow isotopic composition allows to infer past climate variability from ice core stable water isotope records. The concurrent evolution of vapor and surface snow isotopic composition between precipitation events indicates that post-depositional atmosphere-snow humidity exchange influences the snow and hence the ice core isotope signal. To date, however, this is not accounted for in paeleoclimate reconstructions from isotope records. Here we show that vapor-snow exchange explains 36% of the summertime day-to-day δ18O variability of the surface snow between precipitation events, and 53% of the δD variability. Through observations from the Greenland Ice Sheet and accompanying modeling we demonstrate that vapor-snow exchange introduces a warm bias on the summertime snow isotope value relevant for ice core records. In case of long-term variability in atmosphere-snow exchange the relevance for the ice core signal is also variable and thus paleoclimate reconstructions from isotope records should be revisited.

6.
Anal Chem ; 93(23): 8248-8256, 2021 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-34060804

RESUMEN

13C-isotope tracing is a frequently employed approach to study metabolic pathway activity. When combined with the subsequent quantification of absolute metabolite concentrations, this enables detailed characterization of the metabolome in biological specimens and facilitates computational time-resolved flux quantification. Classically, a 13C-isotopically labeled sample is required to quantify 13C-isotope enrichments and a second unlabeled sample for the quantification of metabolite concentrations. The rationale for a second unlabeled sample is that the current methods for metabolite quantification rely mostly on isotope dilution mass spectrometry (IDMS) and thus isotopically labeled internal standards are added to the unlabeled sample. This excludes the absolute quantification of metabolite concentrations in 13C-isotopically labeled samples. To address this issue, we have developed and validated a new strategy using an unlabeled internal standard to simultaneously quantify metabolite concentrations and 13C-isotope enrichments in a single 13C-labeled sample based on gas chromatography-mass spectrometry (GC/MS). The method was optimized for amino acids and citric acid cycle intermediates and was shown to have high analytical precision and accuracy. Metabolite concentrations could be quantified in small tissue samples (≥20 mg). Also, we applied the method on 13C-isotopically labeled mammalian cells treated with and without a metabolic inhibitor. We proved that we can quantify absolute metabolite concentrations and 13C-isotope enrichments in a single 13C-isotopically labeled sample.


Asunto(s)
Aminoácidos , Carbono , Animales , Isótopos de Carbono , Cromatografía de Gases y Espectrometría de Masas , Marcaje Isotópico , Espectrometría de Masas
7.
Biotechnol Bioeng ; 118(2): 745-758, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-33073364

RESUMEN

Lactate production in anaerobic carbohydrate fermentations with mixed cultures of microorganisms is generally observed only in very specific conditions: the reactor should be run discontinuously and peptides and B vitamins must be present in the culture medium as lactic acid bacteria (LAB) are typically auxotrophic for amino acids. State-of-the-art anaerobic fermentation models assume that microorganisms optimise the adenosine triphosphate (ATP) yield on substrate and therefore they do not predict the less ATP efficient lactate production, which limits their application for designing lactate production in mixed-culture fermentations. In this study, a metabolic model taking into account cellular resource allocation and limitation is proposed to predict and analyse under which conditions lactate production from glucose can be beneficial for microorganisms. The model uses a flux balances analysis approach incorporating additional constraints from the resource allocation theory and simulates glucose fermentation in a continuous reactor. This approach predicts lactate production is predicted at high dilution rates, provided that amino acids are in the culture medium. In minimal medium and lower dilution rates, mostly butyrate and no lactate is predicted. Auxotrophy for amino acids of LAB is identified to provide a competitive advantage in rich media because less resources need to be allocated for anabolic machinery and higher specific growth rates can be achieved. The Matlab™ codes required for performing the simulations presented in this study are available at https://doi.org/10.5281/zenodo.4031144.


Asunto(s)
Reactores Biológicos , Simulación por Computador , Ácido Láctico/biosíntesis , Lactobacillales/crecimiento & desarrollo , Modelos Biológicos , Anaerobiosis , Técnicas de Cocultivo
8.
Biotechnol Bioeng ; 117(8): 2571-2587, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-32374413

RESUMEN

The global market of butanol is increasing due to its growing applications as solvent, flavoring agent, and chemical precursor of several other compounds. Recently, the superior properties of n-butanol as a biofuel over ethanol have stimulated even more interest. (Bio)butanol is natively produced together with ethanol and acetone by Clostridium species through acetone-butanol-ethanol fermentation, at noncompetitive, low titers compared to petrochemical production. Different butanol production pathways have been expressed in Escherichia coli, a more accessible host compared to Clostridium species, to improve butanol titers and rates. The bioproduction of butanol is here reviewed from a historical and theoretical perspective. All tested rational metabolic engineering strategies in E. coli to increase butanol titers are reviewed: manipulation of central carbon metabolism, elimination of competing pathways, cofactor balancing, development of new pathways, expression of homologous enzymes, consumption of different substrates, and molecular biology strategies. The progress in the field of metabolic modeling and pathway generation algorithms and their potential application to butanol production are also summarized here. The main goals are to gather all the strategies, evaluate the respective progress obtained, identify, and exploit the outstanding challenges.


Asunto(s)
Butanoles/metabolismo , Escherichia coli , Ingeniería Metabólica/métodos , Biocombustibles , Escherichia coli/genética , Escherichia coli/metabolismo , Fermentación
9.
Microb Cell Fact ; 19(1): 116, 2020 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-32471427

RESUMEN

BACKGROUND: Microbial metabolism is highly dependent on the environmental conditions. Especially, the substrate concentration, as well as oxygen availability, determine the metabolic rates. In large-scale bioreactors, microorganisms encounter dynamic conditions in substrate and oxygen availability (mixing limitations), which influence their metabolism and subsequently their physiology. Earlier, single substrate pulse experiments were not able to explain the observed physiological changes generated under large-scale industrial fermentation conditions. RESULTS: In this study we applied a repetitive feast-famine regime in an aerobic Escherichia coli culture in a time-scale of seconds. The regime was applied for several generations, allowing cells to adapt to the (repetitive) dynamic environment. The observed response was highly reproducible over the cycles, indicating that cells were indeed fully adapted to the regime. We observed an increase of the specific substrate and oxygen consumption (average) rates during the feast-famine regime, compared to a steady-state (chemostat) reference environment. The increased rates at same (average) growth rate led to a reduced biomass yield (30% lower). Interestingly, this drop was not followed by increased by-product formation, pointing to the existence of energy-spilling reactions. During the feast-famine cycle, the cells rapidly increased their uptake rate. Within 10 s after the beginning of the feeding, the substrate uptake rate was higher (4.68 µmol/gCDW/s) than reported during batch growth (3.3 µmol/gCDW/s). The high uptake led to an accumulation of several intracellular metabolites, during the feast phase, accounting for up to 34% of the carbon supplied. Although the metabolite concentrations changed rapidly, the cellular energy charge remained unaffected, suggesting well-controlled balance between ATP producing and ATP consuming reactions. CONCLUSIONS: The adaptation of the physiology and metabolism of E. coli under substrate dynamics, representative for large-scale fermenters, revealed the existence of several cellular mechanisms coping with stress. Changes in the substrate uptake system, storage potential and energy-spilling processes resulted to be of great importance. These metabolic strategies consist a meaningful step to further tackle reduced microbial performance, observed under large-scale cultivations.


Asunto(s)
Técnicas de Cultivo Celular por Lotes/métodos , Escherichia coli/crecimiento & desarrollo , Escherichia coli/metabolismo , Reactores Biológicos , Fermentación , Glucosa/metabolismo , Oxígeno/metabolismo
10.
Hautarzt ; 69(11): 938-940, 2018 Nov.
Artículo en Alemán | MEDLINE | ID: mdl-29737365

RESUMEN

The case of a man with type I allergy after the intake of camomile tea is presented. About 30 min after consumption he was hospitalised with palmar pruritus, swelling of the eyelids, upper lip and nasal mucosa as well as narrowness of the throat. Hereditary angioedema was excluded. The skin prick test confirmed the diagnosis of a type I allergy due to camomile tea.


Asunto(s)
Anafilaxia , Manzanilla , , Manzanilla/efectos adversos , Humanos , Masculino , Prurito , Pruebas Cutáneas , Té/efectos adversos
11.
Microb Cell Fact ; 16(1): 161, 2017 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-28946905

RESUMEN

BACKGROUND: Natural and industrial environments are dynamic with respect to substrate availability and other conditions like temperature and pH. Especially, metabolism is strongly affected by changes in the extracellular space. Here we study the dynamic flux of central carbon metabolism and storage carbohydrate metabolism under dynamic feast/famine conditions in Saccharomyces cerevisiae. RESULTS: The metabolic flux reacts fast and sensitive to cyclic perturbations in substrate availability. Compared to well-documented stimulus-response experiments using substrate pulses, different metabolic responses are observed. Especially, cells experiencing cyclic perturbations do not show a drop in ATP with the addition of glucose, but an immediate increase in energy charge. Although a high glycolytic flux of up to 5.4 mmol g DW-1  h-1 is observed, no overflow metabolites are detected. From famine to feast the glucose uptake rate increased from 170 to 4788 µmol g DW-1  h-1 in 24 s. Intracellularly, even more drastic changes were observed. Especially, the T6P synthesis rate increased more than 100-fold upon glucose addition. This response indicates that the storage metabolism is very sensitive to changes in glycolytic flux and counterbalances these rapid changes by diverting flux into large pools to prevent substrate accelerated death and potentially refill the central metabolism when substrates become scarce. Using 13C-tracer we found a dilution in the labeling of extracellular glucose, G6P, T6P and other metabolites, indicating an influx of unlabeled carbon. It is shown that glycogen and trehalose degradation via different routes could explain these observations. Based on the 13C labeling in average 15% of the carbon inflow is recycled via trehalose and glycogen. This average fraction is comparable to the steady-state turnover, but changes significantly during the cycle, indicating the relevance for dynamic regulation of the metabolic flux. CONCLUSIONS: Comparable to electric energy grids, metabolism seems to use storage units to buffer peaks and keep reserves to maintain a robust function. During the applied fast feast/famine conditions about 15% of the metabolized carbon were recycled in storage metabolism. Additionally, the resources were distributed different to steady-state conditions. Most remarkably is a fivefold increased flux towards PPP that generated a reversed flux of transaldolase and the F6P-producing transketolase reactions. Combined with slight changes in the biomass composition, the yield decrease of 5% can be explained.


Asunto(s)
Isótopos de Carbono/análisis , Saccharomyces cerevisiae/metabolismo , Isótopos de Carbono/metabolismo , Glucosa/metabolismo , Glucógeno/metabolismo , Glucólisis , Marcaje Isotópico , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/genética , Trehalosa/metabolismo
12.
Microb Cell Fact ; 16(1): 90, 2017 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-28535757

RESUMEN

BACKGROUND: The metabolic engineering of Saccharomyces cerevisiae for the production of succinic acid has progressed dramatically, and a series of high-producing hosts are available. At low cultivation pH and high titers, the product transport can become bidirectional, i.e. the acid is reentering the cell and is again exported or even catabolized. Here, a quantitative approach for the identification of product recycling fluxes is developed. RESULTS: The metabolic flux distributions at two time-points of the fermentation process were analyzed. 13C labeled succinic acid was added to the extracellular space and intracellular enrichments were measured and subsequently used for the estimation of metabolic fluxes. The labeling was introduced by a labeling switch experiment, leading to an immediate labeling of about 85% of the acid while keeping the total acid concentration constant. Within 100 s significant labeling enrichment of the TCA cycle intermediates fumarate, iso-citrate and α-ketoglutarate was observed, while no labeling was detected for malate and citrate. These findings suggest that succinic acid is rapidly exchanged over the cellular membrane and enters the oxidative TCA cycle. Remarkably, in the oxidative direction malate 13C enrichment was not detected, indicating that there is no flux going through this metabolite pool. Using flux modeling and thermodynamic assumptions on compartmentation it was concluded that malate must be predominantly cytosolic while fumarate and iso-citrate were more dominant in the mitochondria. CONCLUSIONS: Adding labeled product without changing the extracellular environment allowed to quantify intracellular metabolic fluxes under high producing conditions and identify product degradation cycles. In the specific case of succinic acid production, compartmentation was found to play a major role, i.e. the presence of metabolic activity in two different cellular compartments lead to intracellular product degradation reducing the yield. We also observed that the flux from glucose to succinic acid branches at two points in metabolism: (1) At the level of pyruvate, and (2) at cytosolic malate which was not expected.


Asunto(s)
Citoplasma/metabolismo , Análisis de Flujos Metabólicos , Saccharomyces cerevisiae/metabolismo , Ácido Succínico/metabolismo , Isótopos de Carbono , Ciclo del Ácido Cítrico , Citoplasma/química , Fermentación , Fumaratos/metabolismo , Glucosa/metabolismo , Concentración de Iones de Hidrógeno , Malatos/metabolismo , Ingeniería Metabólica/métodos , Mitocondrias/metabolismo , Saccharomyces cerevisiae/citología
13.
Nutr Metab Cardiovasc Dis ; 27(11): 999-1007, 2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-29074383

RESUMEN

BACKGROUND AND AIMS: As a modifiable lifestyle factor, diet is hypothesized to play an important role in the progression of atherosclerosis. The aim of this study was to explore associations of comprehensive dietary patterns derived by cluster analysis with degree and progression of coronary artery calcification (CAC) over five years of follow-up. METHODS AND RESULTS: In the population-based Heinz Nixdorf Recall study, 3718 participants (45-75 years; 47.6% men) without coronary heart disease completed a food frequency questionnaire at baseline. Five distinct dietary patterns were identified using cluster analysis: "Health-conscious", "Traditional German/Less alcohol", "Mediterranean-like", "Western" and "Animal fat/Alcohol" (used as reference). CAC was measured using electron-beam computed tomography at baseline and five years later. CAC after five years was predicted based on sex- and age-specific baseline percentiles. After comparing observed and predicted CAC Scores, CAC progression was classified as slow, expected, or rapid. Compared to "Animal fat/Alcohol" diet, a "Mediterranean-like" diet was associated with a relative risk (RR) for a rapid CAC progression in both sexes (men: 0.61; 95%-confidence interval [95%-CI]: 0.41; 0.90; women: 0.59; 95%-CI: 0.45; 0.78). Furthermore, reduced RRs were observed in women with a "Health-conscious" and a "Traditional German/Less alcohol" diet (0.63; 95%-CI: 0.47; 0.84, respectively 0.69; 95%-CI: 0.52; 0.90). No association was observed for a "Western" diet for both sexes. Similar results were revealed for degree of CAC. CONCLUSION: The study results support the hypothesis that a "Mediterranean-like" diet is associated with a lower CAC-progression and lower degree of CAC in men and women.


Asunto(s)
Enfermedad de la Arteria Coronaria/epidemiología , Dieta , Conducta Alimentaria , Calcificación Vascular/epidemiología , Anciano , Consumo de Bebidas Alcohólicas , Análisis por Conglomerados , Angiografía por Tomografía Computarizada , Angiografía Coronaria/métodos , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/prevención & control , Dieta/efectos adversos , Encuestas sobre Dietas , Dieta Saludable , Dieta Mediterránea , Dieta Occidental , Grasas de la Dieta , Progresión de la Enfermedad , Femenino , Alemania/epidemiología , Humanos , Modelos Lineales , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Estudios Prospectivos , Factores Protectores , Factores de Riesgo , Índice de Severidad de la Enfermedad , Factores de Tiempo , Calcificación Vascular/diagnóstico por imagen , Calcificación Vascular/prevención & control
14.
Ann Oncol ; 27(2): 225-32, 2016 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-26578726

RESUMEN

Immunoscore is a prognostic tool defined to quantify in situ immune cell infiltrates and appears highly promising as a supplement to the tumor-node-metastasis (TNM) classification of various tumors. In colorectal cancer, an international task force has initiated prospective multicenter studies aiming to implement TNM-Immunoscore (TNM-I) in a routine clinical setting. In breast cancer, recommendations for the evaluation of tumor-infiltrating lymphocytes (TILs) have been proposed by an international working group. Regardless of promising results, there are potential obstacles related to implementing TNM-I into the clinic. Diverse methods may be needed for different malignancies and even within each cancer entity. Nevertheless, a uniform approach across malignancies would be advantageous. In nonsmall-cell lung cancer (NSCLC), there are several previous reports indicating an apparent prognostic importance of TILs, but studies on TILs in a TNM-I setting are sparse and no general recommendations are made. However, recently published data is promising, evoking a realistic hope of a clinical useful NSCLC TNM-I. This review will focus on the TNM-I potential in NSCLC and propose strategies for clinical implementation of a TNM-I in resected NSCLC.


Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/patología , Neoplasias Pulmonares/patología , Linfocitos Infiltrantes de Tumor/patología , Carcinoma de Pulmón de Células no Pequeñas/diagnóstico , Carcinoma de Pulmón de Células no Pequeñas/mortalidad , Humanos , Neoplasias Pulmonares/diagnóstico , Neoplasias Pulmonares/mortalidad , Linfocitos Infiltrantes de Tumor/inmunología , Metástasis de la Neoplasia/diagnóstico , Metástasis de la Neoplasia/patología , Estadificación de Neoplasias , Pronóstico , Índice de Severidad de la Enfermedad , Microambiente Tumoral/inmunología
15.
Appl Environ Microbiol ; 82(23): 6831-6845, 2016 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-27637876

RESUMEN

Ammonium is the most common N source for yeast fermentations. Although its transport and assimilation mechanisms are well documented, there have been only a few attempts to measure the in vivo intracellular concentration of ammonium and assess its impact on gene expression. Using an isotope dilution mass spectrometry (IDMS)-based method, we were able to measure the intracellular ammonium concentration in N-limited aerobic chemostat cultivations using three different N sources (ammonium, urea, and glutamate) at the same growth rate (0.05 h-1). The experimental results suggest that, at this growth rate, a similar concentration of intracellular (IC) ammonium, about 3.6 mmol NH4+/literIC, is required to supply the reactions in the central N metabolism, independent of the N source. Based on the experimental results and different assumptions, the vacuolar and cytosolic ammonium concentrations were estimated. Furthermore, we identified a futile cycle caused by NH3 leakage into the extracellular space, which can cost up to 30% of the ATP production of the cell under N-limited conditions, and a futile redox cycle between Gdh1 and Gdh2 reactions. Finally, using shotgun proteomics with protein expression determined relative to a labeled reference, differences between the various environmental conditions were identified and correlated with previously identified N compound-sensing mechanisms.IMPORTANCE In our work, we studied central N metabolism using quantitative approaches. First, intracellular ammonium was measured under different N sources. The results suggest that Saccharomyces cerevisiae cells maintain a constant NH4+ concentration (around 3 mmol NH4+/literIC), independent of the applied nitrogen source. We hypothesize that this amount of intracellular ammonium is required to obtain sufficient thermodynamic driving force. Furthermore, our calculations based on thermodynamic analysis of the transport mechanisms of ammonium suggest that ammonium is not equally distributed, indicating a high degree of compartmentalization in the vacuole. Additionally, metabolomic analysis results were used to calculate the thermodynamic driving forces in the central N metabolism reactions, revealing that the main reactions in the central N metabolism are far from equilibrium. Using proteomics approaches, we were able to identify major changes, not only in N metabolism, but also in C metabolism and regulation.

16.
Biotechnol Bioeng ; 113(5): 1137-47, 2016 May.
Artículo en Inglés | MEDLINE | ID: mdl-26479486

RESUMEN

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


Asunto(s)
Metabolómica/métodos , Saccharomyces cerevisiae/metabolismo , Espectrometría de Masas en Tándem/métodos , Isótopos de Carbono/análisis , Isótopos de Carbono/metabolismo , Cromatografía de Gases y Espectrometría de Masas , Marcaje Isotópico/métodos
17.
Mol Microbiol ; 93(2): 369-89, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24912400

RESUMEN

Most available knowledge on fungal arginine metabolism is derived from studies on Saccharomyces cerevisiae, in which arginine catabolism is initiated by releasing urea via the arginase reaction. Orthologues of the S. cerevisiae genes encoding the first three enzymes in the arginase pathway were cloned from Kluyveromyces lactis and shown to functionally complement the corresponding deletion in S. cerevisiae. Surprisingly, deletion of the single K. lactis arginase gene KlCAR1 did not completely abolish growth on arginine as nitrogen source. Growth rate of the deletion mutant strongly increased during serial transfer in shake-flask cultures. A combination of RNAseq-based transcriptome analysis and (13)C-(15)N-based flux analysis was used to elucidate the arginase-independent pathway. Isotopic (13)C(15)N-enrichment in γ-aminobutyrate revealed succinate as the entry point in the TCA cycle of the alternative pathway. Transcript analysis combined with enzyme activity measurements indicated increased expression in the Klcar1Δ mutant of a guanidinobutyrase (EC.3.5.3.7), a key enzyme in a new pathway for arginine degradation. Expression of the K. lactis KLLA0F27995g (renamed KlGBU1) encoding guanidinobutyrase enabled S. cerevisiae to use guanidinobutyrate as sole nitrogen source and its deletion in K. lactis almost completely abolish growth on this nitrogen source. Phylogenetic analysis suggests that this enzyme activity is widespread in fungi.


Asunto(s)
Arginina/metabolismo , Kluyveromyces/metabolismo , Ureohidrolasas/metabolismo , Secuencia de Aminoácidos , Arginasa/genética , Arginasa/metabolismo , Clonación Molecular , Perfilación de la Expresión Génica , Regulación Fúngica de la Expresión Génica , Genes Fúngicos , Prueba de Complementación Genética , Kluyveromyces/genética , Kluyveromyces/crecimiento & desarrollo , Análisis de Flujos Metabólicos , Mutación , Filogenia , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Homología de Secuencia de Aminoácido , Ácido Succínico/metabolismo , Ureohidrolasas/genética
18.
Z Gastroenterol ; 53(10): 1161-6, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26480051

RESUMEN

OBJECTIVE: The objective of the present study was to analyze the effects of different factors impacting the caliber of the common bile duct (CBD) and a comparison of maximum extrahepatic bile duct caliber in patients with and without a history of cholecystectomy. MATERIAL AND METHODS: A retrospective data analysis was undertaken of 8534 patients (4480 females; 4054 males; average age: 59.2±18.0 years) with sonographic documentation of bile duct caliber. Maximum intra- and extrahepatic bile duct diameters were studied. The normal maximum diameter of the extrahepatic bile duct was defined as 7 mm. In patients who had undergone prior cholecystectomy, a maximum bile duct diameter<10 mm was considered normal. RESULTS: The average maximum diameter of the CBD amounted to 5.3±3.0 mm for the overall collective. In patients who had undergone prior cholecystectomy, maximum CBD diameters in the normal range (<7 mm) were documented in 55%, while larger diameters (>7 mm) were observed in 45%. In the collective of patients without prior cholecystectomy, CBD diameters in the normal range (<7 mm) were found in 81%, with larger diameters observed in only 18.4% of patients. In both subgroups, there was a significant association between age and bile duct diameter (for those with prior cholecystectomy, p=0.0003; without prior cholecystectomy, p<0.0001). No statistically significant influence on CBD diameter was observed for either prior cholecystectomy (p=0.2116) or time interval since cholecystectomy (p=0.3537). Females, both with and without a history of prior cholecystectomy, showed a 1.4-1.5-fold higher risk of exhibiting a CBD diameter>7 mm (for those with prior cholecystectomy, p=0.0485; without prior cholecystectomy, p<0.001). CONCLUSIONS: Our data show a positive correlation between age and CBD diameter. There was no statistically significant relationship between CBD diameter and prior cholecystectomy, postoperative interval and BMI.


Asunto(s)
Colecistectomía/estadística & datos numéricos , Enfermedades del Conducto Colédoco/diagnóstico por imagen , Enfermedades del Conducto Colédoco/epidemiología , Conducto Colédoco/diagnóstico por imagen , Complicaciones Posoperatorias/diagnóstico por imagen , Ultrasonografía/estadística & datos numéricos , Adolescente , Adulto , Distribución por Edad , Femenino , Alemania/epidemiología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Especificidad de Órganos , Complicaciones Posoperatorias/epidemiología , Reproducibilidad de los Resultados , Estudios Retrospectivos , Factores de Riesgo , Sensibilidad y Especificidad , Adulto Joven
19.
Allergy ; 69(5): 632-42, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24661001

RESUMEN

BACKGROUND: Type 2 immune responses directed by Th2 cells and characterized by the signature cytokines IL4, IL5, and IL13 play major pathogenic roles in atopic diseases. Single nucleotide polymorphisms in the human Th2 cytokine locus in particular in a locus control region within the DNA repair gene RAD50, containing several RAD50 DNase1-hypersensitive sites (RHS), have been robustly associated with atopic traits in genome-wide association studies (GWAS). Functional variants in IL13 have been intensely studied, whereas no causative variants for the IL13-independent RAD50 signal have been identified yet. This study aimed to characterize the functional impact of the atopy-associated polymorphism rs2240032 located in the human RHS7 on cis-regulatory activity and differential binding of transcription factors. METHODS: Differential transcription factor binding was analyzed by electrophoretic mobility shift assays (EMSAs) with Jurkat T-cell nuclear extracts. Identification of differentially binding factors was performed using mass spectrometry (LC-MS/MS). Reporter vector constructs carrying either the major or minor allele of rs2240032 were tested for regulating transcriptional activity in Jurkat and HeLa cells. RESULTS: The variant rs2240032 impacts transcriptional activity and allele-specific binding of SMAD3, SP1, and additional putative protein complex partners. We further demonstrate that rs2240032 is located in an RHS7 subunit which itself encompasses repressor activity and might be important for the fine-tuning of transcription regulation within this region. CONCLUSION: The human RHS7 critically contributes to the regulation of gene transcription, and the common atopy-associated polymorphism rs2240032 impacts transcriptional activity and transcription factor binding.


Asunto(s)
Citocinas/genética , Regulación de la Expresión Génica , Hipersensibilidad Inmediata/genética , Hipersensibilidad Inmediata/metabolismo , Región de Control de Posición , Proteína smad3/metabolismo , Factor de Transcripción Sp1/metabolismo , Células Th2/metabolismo , Transcripción Genética , Alelos , Sitios de Unión , Orden Génico , Humanos , Hipersensibilidad Inmediata/inmunología , Desequilibrio de Ligamiento , Motivos de Nucleótidos , Polimorfismo de Nucleótido Simple , Posición Específica de Matrices de Puntuación , Regiones Promotoras Genéticas , Unión Proteica , Secuencias Reguladoras de Ácidos Nucleicos
20.
Water Res ; 250: 121028, 2024 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-38128304

RESUMEN

With the rapid growing availability of metagenome assembled genomes (MAGs) and associated metabolic models, the identification of metabolic potential in individual community members has become possible. However, the field still lacks an unbiassed systematic evaluation of the generated metagenomic information to uncover not only metabolic potential, but also feasibilities of these models under specific environmental conditions. In this study, we present a systematic analysis of the metabolic potential in species of "Candidatus Accumulibacter", a group of polyphosphate-accumulating organisms (PAOs). We constructed a metabolic model of the central carbon metabolism and compared the metabolic potential among available MAGs for "Ca. Accumulibacter" species. By combining Elementary Flux Modes Analysis (EFMA) with max-min driving force (MDF) optimization, we obtained all possible flux distributions of the metabolic network and calculated their individual thermodynamic feasibility. Our findings reveal significant variations in the metabolic potential among "Ca. Accumulibacter" MAGs, particularly in the presence of anaplerotic reactions. EFMA revealed 700 unique flux distributions in the complete metabolic model that enable the anaerobic uptake of acetate and its conversion into polyhydroxyalkanoates (PHAs), a well-known phenotype of "Ca. Accumulibacter". However, thermodynamic constraints narrowed down this solution space to 146 models that were stoichiometrically and thermodynamically feasible (MDF > 0 kJ/mol), of which only 8 were strongly feasible (MDF > 7 kJ/mol). Notably, several novel flux distributions for the metabolic model were identified, suggesting putative, yet unreported, functions within the PAO communities. Overall, this work provides valuable insights into the metabolic variability among "Ca. Accumulibacter" species and redefines the anaerobic metabolic potential in the context of phosphate removal. More generally, the integrated workflow presented in this paper can be applied to any metabolic model obtained from a MAG generated from microbial communities to objectively narrow the expected phenotypes from community members.


Asunto(s)
Betaproteobacteria , Metagenoma , Anaerobiosis , Fósforo/metabolismo , Betaproteobacteria/metabolismo , Redes y Vías Metabólicas , Reactores Biológicos
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