75 research outputs found

    Fructose metabolism in Chromohalobacter salexigens: interplay between the Embden–Meyerhof–Parnas and Entner–Doudoroff pathways

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    Background The halophilic bacterium Chromohalobacter salexigens metabolizes glucose exclusively through the Entner–Doudoroff (ED) pathway, an adaptation which results in inefficient growth, with significant carbon overflow, especially at low salinity. Preliminary analysis of C. salexigens genome suggests that fructose metabolism could proceed through the Entner–Doudoroff and Embden–Meyerhof–Parnas (EMP) pathways. In order to thrive at high salinity, this bacterium relies on the biosynthesis and accumulation of ectoines as major compatible solutes. This metabolic pathway imposes a high metabolic burden due to the consumption of a relevant proportion of cellular resources, including both energy molecules (NADPH and ATP) and carbon building blocks. Therefore, the existence of more than one glycolytic pathway with different stoichiometries may be an advantage for C. salexigens. The aim of this work is to experimentally characterize the metabolism of fructose in C. salexigens. Results Fructose metabolism was analyzed using in silico genome analysis, RT-PCR, isotopic labeling, and genetic approaches. During growth on fructose as the sole carbon source, carbon overflow was not observed in a wide range of salt concentrations, and higher biomass yields were reached. We unveiled the initial steps of the two pathways for fructose incorporation and their links to central metabolism. While glucose is metabolized exclusively through the Entner–Doudoroff (ED) pathway, fructose is also partially metabolized by the Embden–Meyerhof–Parnas (EMP) route. Tracking isotopic label from [1-13C] fructose to ectoines revealed that 81% and 19% of the fructose were metabolized through ED and EMP-like routes, respectively. Activities of enzymes from both routes were demonstrated in vitro by 31P-NMR. Genes encoding predicted fructokinase and 1-phosphofructokinase were cloned and the activities of their protein products were confirmed. Importantly, the protein encoded by csal1534 gene functions as fructose bisphosphatase, although it had been annotated previously as pyrophosphate-dependent phosphofructokinase. The gluconeogenic rather than glycolytic role of this enzyme in vivo is in agreement with the lack of 6-phosphofructokinase activity previously described. Conclusions Overall, this study shows that C. salexigens possesses a greater metabolic flexibility for fructose catabolism, the ED and EMP pathways contributing to a fine balancing of energy and biosynthetic demands and, subsequently, to a more efficient metabolism.University of Murcia and University of Seville was supported by projects: BIO2015-63949-R, BIO2014-54411-C2-1-REuropa MINECO/FEDER RTI2018-094393-B-C21Fundación Séneca (Grant no. 19236/PI/14

    Li abundances in F stars: planets, rotation and galactic evolution

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    We find that hot jupiter host stars within the Teff_\mathrm{eff} range 5900-6300K show lower Li abundances, by 0.14 dex, than stars without detected planets. This offset has a significance at the level 7σ\sigma, pointing to a stronger effect of planet formation on Li abundances when the planets are more massive and migrate close to the star. However, we also find that the average v \textit{sin}i of (a fraction of) stars with hot jupiters is higher on average than for single stars in the same Teff_\mathrm{eff} region, suggesting that rotationally-induced mixing (and not the presence of planets) might be the cause for a greater depletion of Li. We confirm that the mass-metallicity dependence of the Li dip is extended towards [Fe/H] \sim 0.4 dex (beginning at [Fe/H] \sim -0.4 dex for our stars) and that probably reflects the mass-metallicity correlation of stars of the same Teff_\mathrm{eff} on the Main Sequence. We find that for the youngest stars (<< 1.5 Gyr) around the Li dip, the depletion of Li increases with v \textit{sin}i values, as proposed by rotationally-induced depletion models. This suggests that the Li dip consists of fast rotators at young ages whereas the most Li-depleted old stars show lower rotation rates (probably caused by the spin-down during their long lifes). We have also explored the Li evolution with [Fe/H] taking advantage of the metal-rich stars included in our sample. We find that Li abundance reaches its maximum around solar metallicity but decreases in the most metal-rich stars, as predicted by some models of Li Galactic production.Comment: 10 pages, accepted to A&

    Mosaicism of alpha-synuclein gene rearrangements: Report of two unrelated cases of early-onset parkinsonism

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    Dear Sir, In genetics, the term ‘mosaicism’ describes the situation in which groups of cells have a different genetic composition to other cells in an organism. Somatic gene rearrangements due to multiplication or deletion of genes (copy number variation) and/or sections of chromosomes can lead to mosaicism. The presence of multiple copies of the alpha-synuclein gene (SNCA) is known to be associated with Parkinson’s disease (PD) and the severity of symptoms increases with the number of copies of the gene [1]. While the features of PD associated with duplication of SNCA are usually (but not always) typical of the condition [2–3], patients with triplicate copies have atypical features, including rapidly evolving symptoms, severe cognitive impairment, limited response to levodopa, more severe symptoms of dementia and more..

    Bulk and surface switching in Mn-Fe-based Prussian Blue Analogues

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    Many Prussian Blue Analogues are known to show a thermally induced phase transition close to room temperature and a reversible, photo-induced phase transition at low temperatures. This work reports on magnetic measurements, X-ray photoemission and Raman spectroscopy on a particular class of these molecular heterobimetallic systems, specifically on Rb0.81Mn[Fe(CN)6]0.95_1.24H2O, Rb0.97Mn[Fe(CN)6]0.98_1.03H2O and Rb0.70Cu0.22Mn0.78[Fe(CN)6]0.86_2.05H2O, to investigate these transition phenomena both in the bulk of the material and at the sample surface. Results indicate a high degree of charge transfer in the bulk, while a substantially reduced conversion is found at the sample surface, even in case of a near perfect (Rb:Mn:Fe=1:1:1) stoichiometry. Thus, the intrinsic incompleteness of the charge transfer transition in these materials is found to be primarily due to surface reconstruction. Substitution of a large fraction of charge transfer active Mn ions by charge transfer inactive Cu ions leads to a proportional conversion reduction with respect to the maximum conversion that is still stoichiometrically possible and shows the charge transfer capability of metal centers to be quite robust upon inclusion of a neighboring impurity. Additionally, a 532 nm photo-induced metastable state, reminiscent of the high temperature Fe(III)Mn(II) ground state, is found at temperatures 50-100 K. The efficiency of photo-excitation to the metastable state is found to be maximized around 90 K. The photo-induced state is observed to relax to the low temperature Fe(II)Mn(III) ground state at a temperature of approximately 123 K.Comment: 12 pages, 8 figure

    Bases moleculars de la cistinúria

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    Els cDNA identificats actualment de transportadors d'aminoàcids en mamífers poden ser agrupats en quatre famílies. Una d'aquestes famílies la componen les proteïnes rBAT i la cadena pesada (hc) de l'antigen de superfície de membrana anomenat 4F2. Els RNA que codifiquen aquestes dues proteïnes indueixen activitat d'un sistema de transport d'aminoàcids tipus b (rBAT) i un altre de tipus y+L (4F2hc) en oocits de Xenopus laevis. Ambdós transportadors tenen un mecanisme de bescanvi obligatori d'aminoàcids que, en el cas de rBAT, pot acumular, per aquest mecanisme de transport actiu terciari , substrats a través de la membrana plasmàtica fins a 30-50 vegades en l'oòcit de Xenopus . Sorprenentment, tant rBAT com 4F2hc no són suficientment hidrofòbics i no semblen proteïnes formadores de porus en membranes. Això ha suggerit la hipòtesi que rBAT i 4F2hc són subunitats o moduladors dels corresponents transportadors. És significatiu que taut per a rBAT com per a 4F2hc s'ha suggerit o demostrat, respectivament , la seva associació amb subunitats lleugeres d'aproximadament 40 kD en una estructura de tipus heterodimèric

    The Role of Native Language and the Fundamental Design of the Auditory System in Detecting Rhythm Changes

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    Accepted December 13, 2018Purpose: We investigated whether rhythm discrimination is mainly driven by the native language of the listener or by the fundamental design of the human auditory system and universal cognitive mechanisms shared by all people irrespective of rhythmic patterns in their native language. Method: In multiple experiments, we asked participants to listen to 2 continuous acoustic sequences and to determine whether their rhythms were the same or different (AX discrimination). Participants were native speakers of 4 languages with different rhythmic properties (Spanish, French, English, and German) to understand whether the predominant rhythmic patterns of a native language affect sensitivity, bias, and reaction time in detecting rhythmic changes in linguistic (Experiment 2) and in nonlinguistic (Experiments 1 and 2) acoustic sequences. We examined sensitivity and bias measures, as well as reaction times. We also computed Bayes factors in order to assess the effect of native language. Results: All listeners performed better (i.e., responded faster and manifested higher sensitivity and accuracy) when detecting the presence or absence of a rhythm change when the 1st stimulus in an AX test pair exhibited regular rhythm (i.e., a syllable-timed rhythmic pattern) than when the 1st stimulus exhibited irregular rhythm (i.e., stress-timed rhythmic pattern). This result pattern was observed both on linguistic and nonlinguistic stimuli and was not modulated by the native language of the participant. Conclusion: We conclude that rhythm change detection is a fundamental function of a processing system that relies on general auditory mechanisms and is not modulated by linguistic experience.The authors acknowledge support from Spanish Ministry of Economy and Competitiveness Grant PSI2017-82563-P (awarded to A. G. S.), the “Severo Ochoa” Programme for Centres/Units of Excellence in R&D Grant SEV-2015-490 (BCBL), and the Basque Foundation for Science Grant IKERBASQUE (awarded to A. G. S. and M. O.). D. M. G. was supported by Grant PIA/Basal FB0003 from the Chilean Research Council. L. P. was supported by the Spanish Ministry of Economy and Competitiveness via Juan de la Cierva fellowship

    Determinación del nivel de antropización de humedales como criterio para la planificación ecológica de la cuenca del lago Budi, IX Región de La Araucanía, Chile

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    The level of human impact on the wetlands of the Lago Budi Basin was established, as a function of the degree of alteration to the basin and the degree of alteration to the wetlands. The former was evaluated on the basis of a spatial analysis of the fragility and stability of the hydrographical basin. The latter through a modified impact model, with a panel of experts who evaluated the fulfilment of the wetlands' function and their state. Four principal types of wetlands were recognized: estuarine, meadow, waterside and marshy. It was found that 98% of the total surface presents a high degree of alteration, as determined by its instability and fragility. Farm use was weighted as the principal agent of alteration of the wetlands' functions, with 61% of this showing alteration in the maximum degree. This evaluation makes it possible to differentiate areas and generate base criteria for the conservation of wetlands in the basin.Se determinó el nivel de antropización de los humedales de la cuenca del Budi, en función del grado de alteración de cuencas y el grado de alteración de humedales. El primero, evaluado a partir del análisis espacial de la fragilidad y estabilidad de la hoya hidrográfica. El segundo, a través de un modelo de impacto modificado, con panel de expertos que valoró el cumplimiento de funciones de humedales y su estado. Se reconocieron principalmente 4 tipos de humedales: estuarino, palustre, ribereño y de marisma. Por otro lado, el 98% de la superficie total presenta altos grados de alteración, determinados por su inestabilidad y fragilidad. El uso agrícola fue ponderado como el principal agente de alteración de las funciones de los humedales, presentándose un 61% de estos en categoría de máxima alteración. La evaluación realizada permite discriminar áreas y generar criterios de base para la conservación de humedales en la cuenca

    Estimating a threshold price for CO2 emissions of buildings to improve their energy performance level. Case study of a new Spanish home

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    Energy consumption in homes produces CO2. In many countries, building regulations are being set to enable energy efficiency performance levels to be issued. In Spain, there is a regulated procedure to certify the energy performance of buildings according to their CO2 emissions. Consequently, some software tools have been design to simulate buildings and to obtain their energy consumption and CO2 emissions. In this paper the investment, maintenance and energy consumption costs are calculated for different energy performance levels and for various climatic zones, in a single-family home. According to the results, more energy efficient buildings imply higher construction and maintenance costs, which are not compensated by lower energy costs. Therefore, under current conditions, economic criteria do not support the improvement of the energy efficiency of a dwelling. 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    Chronicle of an early demise, surname extinction in the fifteenth and the seventeenth centuries

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    This is the Author’s Original Manuscript of an article published by Taylor & Francis in Historical Methods: A Journal of Quantitative and Interdisciplinary History on 2018, available online: http://www.tandfonline.com/10.1080/01615440.2018.1462747It has been amply demonstrated that individuals' reproductive capability is the key explanatory phenomenon for understanding onomastic disappearance during the early modern period. This article analyzes the evolution and consequences of surname extinction in a specific population: Catalonia in the sixteenth and seventeenth centuries. In this article two aspects are examined. First, the observed disappearance of surnames is estimated through historical data collected in the Llibres d'Esposalles (Marriage Books) from 1481 to 1600 at Barcelona Cathedral. Second, the estimated natural extinction of those surnames registered in 1481 is forecast by applying a statistical branching processResearch has been funded by Projects MTM2016-76969-P (Spanish State Research Agency, AEI) and MTM2013-41383-P (Spanish Ministry of Economy, Industry and Competitiveness), both co-funded by the European Regional Development Fund (ERDF), IAP network from Belgian Science Policy. Work of J. Ameijeiras-Alonso has been supported by the Ph.D. Grant BES-2014-071006 from the Spanish Ministry of Economy, Industry and CompetitivenessNO

    A quantum-chemical study of the binding ability of βXaaHisGlyHis towards copper(II) ion

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    The present study analyzed binding of Cu2+ to tetrapeptides in water solution at several levels of theoretical approximation. The methods used to study the energetic and structural properties of the complexes in question include semiempirical hamiltonians, density functional theory as well as ab initio approaches including electron correlation effects. In order to shed light on the character of interactions between Cu2+ and peptides, which are expected to be mainly electrostatic in nature, decomposition of interaction energy into physically meaningful components was applied
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