251 research outputs found

    Bringing global gyrokinetic turbulence simulations to the transport timescale using a multiscale approach

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    The vast separation dividing the characteristic times of energy confinement and turbulence in the core of toroidal plasmas makes first-principles prediction on long timescales extremely challenging. Here we report the demonstration of a multiple-timescale method that enables coupling global gyrokinetic simulations with a transport solver to calculate the evolution of the self-consistent temperature profile. This method, which exhibits resiliency to the intrinsic fluctuations arising in turbulence simulations, holds potential for integrating nonlocal gyrokinetic turbulence simulations into predictive, whole-device models.Comment: 7 pages, 3 figure

    H008 Le blocage des récepteurs AT1 de L′angiotensine II inhibe L′hypertrophie ventriculaire gauche et L′activation de FHL1 chez la souris hétérozygote déficiente en cMyBP-C

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    Les mutations de la protéine C cardiaque (cMyBP-C) sont une cause de cardiomyopathies hypertrophiques (CMH). Les souris transgéniques hétérozygotes défi cientes en cMyBP-C (HET) présentent une CMH d′apparition tardive à fonction systolique conservée. Le système rénine angiotensine (SRA) cardiaque joue un rôle important dans l′hypertrophie, mais son rôle dans le développement d′une CMH génétiquement déterminée a été peu étudié.Cette étude évaluait le rôle du SRA dans l′induction de la CMH chez la souris HET. Des souris HET et sauvages (WT), âgées de 5 mois, ont été traitées par irbésartan (50mg/kg/jour) ou placebo pendant 8 semaines. L′expression dans le ventricule gauche (VG) des gènes de l′enzyme de conversion de l′angiotensine I (ACE), du récepteur AT1 de l′angiotensine II (AGTR1), de la calcineurine A (PPP3CB) de la calcipressin 1 (RCAN1), et de FHL1 (four and a half LIM domains 1, une protéine associée à cMyBP-C au sein du sarcomère) a été analysée par RT-qPCR.Après 8 semaines de traitement, la pression artérielle est normale dans tous les groupes. Le poids du VG/poids du corps des souris HET est augmenté par rapport aux WT (3,9±0,3 vs. 3,3±0,4mg/g; p<0.01) dans le groupe placebo. Dans les groupes traités par irbésartan, ce rapport est comparable pour les souris HET (3,4±0,5mg/g) et WT (3,2±0,4mg/g; p=ns). L′expression des gènes de l′ACE, PPP3CB et RCAN1 est comparable entre les souris HET et WT et n′est pas affectée par le traitement par irbésartan. L′expression d′AGTR1 est similaire chez les souris HET et WT traitées par placebo mais augmente après traitement par irbésartan uniquement chez les souris HET. A l′inverse, l′expression de FHL1 est activée chez les souris HET par rapport aux souris WT mais cette augmentation est prévenue par le traitement par irbésartan.En conclusion, chez la souris cMyBP-C, le développement de l′hypertrophie est accompagné par une augmentation de l′expression du gène FHL1 dans le VG. Le traitement par irbésartan inhibe l′hypertrophie et l′activation de l′expression de FHL1 don′t le mécanisme reste à déterminer

    Development of a human model for the study of effects of hypoxia, exercise, and sildenafil on cardiac and vascular function in chronic heart failure

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    Background: Pulmonary hypertension is associated with poor outcome in patients with chronic heart failure (CHF) and may be a therapeutic target. Our aims were to develop a noninvasive model for studying pulmonary vasoreactivity in CHF and characterize sildenafil's acute cardiovascular effects. Methods and Results: In a crossover study, 18 patients with CHF participated 4 times [sildenafil (2 × 20 mg)/or placebo (double-blind) while breathing air or 15% oxygen] at rest and during exercise. Oxygen saturation (SaO2) and systemic vascular resistance were recorded. Left and right ventricular (RV) function and transtricuspid systolic pressure gradient (RVTG) were measured echocardiographically. At rest, hypoxia caused SaO2 (P = 0.001) to fall and RVTG to rise (5 ± 4 mm Hg; P = 0.001). Sildenafil reduced SaO2 (−1 ± 2%; P = 0.043), systemic vascular resistance (−87 ± 156 dyn·s−1·cm−2; P = 0.034), and RVTG (−2 ± 5 mm Hg; P = 0.05). Exercise caused cardiac output (2.1 ± 1.8 L/min; P &lt; 0.001) and RVTG (19 ± 11 mm Hg; P &lt; 0.0001) to rise. The reduction in RVTG with sildenafil was not attenuated by hypoxia. The rise in RVTG with exercise was not substantially reduced by sildenafil. Conclusions: Sildenafil reduces SaO2 at rest while breathing air, this was not exacerbated by hypoxia, suggesting increased ventilation–perfusion mismatching due to pulmonary vasodilation in poorly ventilated lung regions. Sildenafil reduces RVTG at rest and prevents increases caused by hypoxia but not by exercise. This study shows the usefulness of this model to evaluate new therapeutics in pulmonary hypertension

    Mitochondrial genome diversity across the subphylum Saccharomycotina

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    IntroductionEukaryotic life depends on the functional elements encoded by both the nuclear genome and organellar genomes, such as those contained within the mitochondria. The content, size, and structure of the mitochondrial genome varies across organisms with potentially large implications for phenotypic variance and resulting evolutionary trajectories. Among yeasts in the subphylum Saccharomycotina, extensive differences have been observed in various species relative to the model yeast Saccharomyces cerevisiae, but mitochondrial genome sampling across many groups has been scarce, even as hundreds of nuclear genomes have become available.MethodsBy extracting mitochondrial assemblies from existing short-read genome sequence datasets, we have greatly expanded both the number of available genomes and the coverage across sparsely sampled clades.ResultsComparison of 353 yeast mitochondrial genomes revealed that, while size and GC content were fairly consistent across species, those in the genera Metschnikowia and Saccharomyces trended larger, while several species in the order Saccharomycetales, which includes S. cerevisiae, exhibited lower GC content. Extreme examples for both size and GC content were scattered throughout the subphylum. All mitochondrial genomes shared a core set of protein-coding genes for Complexes III, IV, and V, but they varied in the presence or absence of mitochondrially-encoded canonical Complex I genes. We traced the loss of Complex I genes to a major event in the ancestor of the orders Saccharomycetales and Saccharomycodales, but we also observed several independent losses in the orders Phaffomycetales, Pichiales, and Dipodascales. In contrast to prior hypotheses based on smaller-scale datasets, comparison of evolutionary rates in protein-coding genes showed no bias towards elevated rates among aerobically fermenting (Crabtree/Warburg-positive) yeasts. Mitochondrial introns were widely distributed, but they were highly enriched in some groups. The majority of mitochondrial introns were poorly conserved within groups, but several were shared within groups, between groups, and even across taxonomic orders, which is consistent with horizontal gene transfer, likely involving homing endonucleases acting as selfish elements.DiscussionAs the number of available fungal nuclear genomes continues to expand, the methods described here to retrieve mitochondrial genome sequences from these datasets will prove invaluable to ensuring that studies of fungal mitochondrial genomes keep pace with their nuclear counterparts

    Extensive loss of cell-cycle and DNA repair genes in an ancient lineage of bipolar budding yeasts

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    Cell-cycle checkpoints and DNA repair processes protect organisms from potentially lethal mutational damage. Compared to other budding yeasts in the subphylum Saccharomycotina, we noticed that a lineage in the genus Hanseniaspora exhibited very high evolutionary rates, low Guanine–Cytosine (GC) content, small genome sizes, and lower gene numbers. To better understand Hanseniaspora evolution, we analyzed 25 genomes, including 11 newly sequenced, representing 18/21 known species in the genus. Our phylogenomic analyses identify two Hanseniaspora lineages, a faster-evolving lineage (FEL), which began diversifying approximately 87 million years ago (mya), and a slower-evolving lineage (SEL), which began diversifying approximately 54 mya. Remarkably, both lineages lost genes associated with the cell cycle and genome integrity, but these losses were greater in the FEL. E.g., all species lost the cell-cycle regulator WHIskey 5 (WHI5), and the FEL lost components of the spindle checkpoint pathway (e.g., Mitotic Arrest-Deficient 1 [MAD1], Mitotic Arrest-Deficient 2 [MAD2]) and DNA-damage–checkpoint pathway (e.g., Mitosis Entry Checkpoint 3 [MEC3], RADiation sensitive 9 [RAD9]). Similarly, both lineages lost genes involved in DNA repair pathways, including the DNA glycosylase gene 3-MethylAdenine DNA Glycosylase 1 (MAG1), which is part of the base-excision repair pathway, and the DNA photolyase gene PHotoreactivation Repair deficient 1 (PHR1), which is involved in pyrimidine dimer repair. Strikingly, the FEL lost 33 additional genes, including polymerases (i.e., POLymerase 4 [POL4] and POL32) and telomere-associated genes (e.g., Repressor/ activator site binding protein-Interacting Factor 1 [RIF1], Replication Factor A 3 [RFA3], Cell Division Cycle 13 [CDC13], Pbp1p Binding Protein [PBP2]). Echoing these losses, molecular evolutionary analyses reveal that, compared to the SEL, the FEL stem lineage underwent a burst of accelerated evolution, which resulted in greater mutational loads, homopolymer instabilities, and higher fractions of mutations associated with the common endogenously damaged base, 8-oxoguanine. We conclude that Hanseniaspora is an ancient lineage that has diversified and thrived, despite lacking many otherwise highly conserved cell-cycle and genome integrity genes and pathways, and may represent a novel, to our knowledge, system for studying cellular life without them.Fil: Steenwyk, Jacob L.. Vanderbilt University; Estados UnidosFil: Opulente, Dana A.. University of Wisconsin; Estados UnidosFil: Kominek, Jacek. University of Wisconsin; Estados UnidosFil: Shen, Xing-Xing. Vanderbilt University; Estados UnidosFil: Zhou, Xiaofan. South China Agricultural University; ChinaFil: Labella, Abigail L.. Vanderbilt University; Estados UnidosFil: Bradley, Noah P.. Vanderbilt University; Estados UnidosFil: Eichman, Brandt F.. Vanderbilt University; Estados UnidosFil: Cadez, Neza. University of Ljubljana; EsloveniaFil: Libkind Frati, Diego. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; ArgentinaFil: DeVirgilio, Jeremy. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Hulfachor, Amanda Beth. University of Wisconsin; Estados UnidosFil: Kurtzman, Cletus P.. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Hittinger, Chris Todd. University of Wisconsin; Estados UnidosFil: Rokas, Antonis. Vanderbilt University; Estados Unido

    The future of fungi: threats and opportunities

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    The fungal kingdom represents an extraordinary diversity of organisms with profound impacts across animal, plant, and ecosystem health. Fungi simultaneously support life, by forming beneficial symbioses with plants and producing life-saving medicines, and bring death, by causing devastating diseases in humans, plants, and animals. With climate change, increased antimicrobial resistance, global trade, environmental degradation, and novel viruses altering the impact of fungi on health and disease, developing new approaches is now more crucial than ever to combat the threats posed by fungi and to harness their extraordinary potential for applications in human health, food supply, and environmental remediation. To address this aim, the Canadian Institute for Advanced Research (CIFAR) and the Burroughs Wellcome Fund convened a workshop to unite leading experts on fungal biology from academia and industry to strategize innovative solutions to global challenges and fungal threats. This report provides recommendations to accelerate fungal research and highlights the major research advances and ideas discussed at the meeting pertaining to 5 major topics: (1) Connections between fungi and climate change and ways to avert climate catastrophe; (2) Fungal threats to humans and ways to mitigate them; (3) Fungal threats to agriculture and food security and approaches to ensure a robust global food supply; (4) Fungal threats to animals and approaches to avoid species collapse and extinction; and (5) Opportunities presented by the fungal kingdom, including novel medicines and enzymes

    Natural law, non-voluntary euthanasia, and public policy

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    © 2019 by Emerald Publishing Limited. Natural Law philosophy asserts that there are universally binding and universally evident principles that can be determined to guide the actions of persons. Moreover, many of these principles have been enshrined in both statute and common law, thus ensuring their saliency for staff and institutions charged with palliative care. The authors examine the often emotive and politicized matter of (non-voluntary) euthanasia – acts or omissions made with the intent of causing or hastening death – with reference to Natural Law philosophy. This leads us to propose a number of important public policy remedies to ensure dignity in dying for the patient, and their associates

    Hybridization and adaptive evolution of diverse Saccharomyces species for cellulosic biofuel production

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    Additional file 15. Summary of whole genome sequencing statistics
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