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DIALNET OAI Articles (790.801 recursos)

Dialnet (Difusión de Alertas en la Red) es una plataforma de recursos y servicios documentales, cuyo objetivo fundamental se centra en mejorar la visibilidad y el acceso a la literatura científica hispana a través de Internet.

Geociencias. Medio ambiente

Mostrando recursos 1 - 20 de 15.099

  1. Migratory control policies in Spain and the United States

    Madeira, Paulo Miguel

  2. A four-helix bundle stores copper for methane oxidation

    Vita, Nicolas; Platsaki, Semeli; Baslé, Arnaud; Allen, Stephen J.; Paterson, Neil G.; Crombie, Andrew T.; Murrell, Colin J.; Waldron, Kevin J.; Dennison, Christopher
    Methane-oxidizing bacteria (methanotrophs) require large quantities of copper for the membrane-bound (particulate) methane monooxygenase1,2. Certain methanotrophs are also able to switch to using the iron-containing soluble methane monooxygenase to catalyse methane oxidation, with this switchover regulated by copper3,4. Methane monooxygenases are nature’s primary biological mechanism for suppressing atmospheric levels of methane, a potent greenhouse gas. Furthermore, methanotrophs and methane monooxygenases have enormous potential in bioremediation and for biotransformations producing bulk and fine chemicals, and in bioenergy, particularly considering increased methane availability from renewable sources and hydraulic fracturing of shale rock5,6. Here we discover and characterize a novel copper storage protein...

  3. Orientation-specific joining of aid-initiated dna breaks promotes antibody class switching

    Dong, Junchao; Panchakshari, Rohit A.; Zhang, Tingting; Zhang, Yu; Hu, Jiazhi; Volpi, Sabrina A.; Meyers, Robin M.
    During B-cell development, RAG endonuclease cleaves immunoglobulin heavy chain (IgH) V, D, and J gene segments and orchestrates their fusion as deletional events that assemble a V(D)J exon in the same transcriptional orientation as adjacent Cµ constant region exons1,2. In mice, six additional sets of constant region exons (CHs) lie 100–200 kilobases downstream in the same transcriptional orientation as V(D)J and Cµ exons2. Long repetitive switch (S) regions precede Cµ and downstream CHs. In mature B cells, class switch recombination (CSR) generates different antibody classes by replacing Cµ with a downstream CH (ref. 2). Activation-induced cytidine deaminase (AID) initiates CSR...

  4. Ggggcc repeat expansion in c9orf72 compromises nucleocytoplasmic transport

    Freibaum, Brian D.; Lu, Yubing; Lopez Gonzalez, Rodrigo; Kim, Nam Chul; Almeida, Sandra; Lee, Kyung-Ha
    The GGGGCC (G4C2) repeat expansion in a noncoding region of C9orf72 is the most common cause of sporadic and familial forms of amyotrophic lateral sclerosis and frontotemporal dementia1,2. The basis for pathogenesis is unknown. To elucidate the consequences of G4C2 repeat expansion in a tractable genetic system, we generated transgenic fly lines expressing 8, 28 or 58 G4C2-repeat-containing transcripts that do not have a translation start site (AUG) but contain an open-reading frame for green fluorescent protein to detect repeat-associated non-AUG (RAN) translation. We show that these transgenic animals display dosage-dependent, repeat-length-dependent degeneration in neuronal tissues and RAN translation of...

  5. Regulation of mitochondrial morphology and function by stearoylation of TFR1

    Senyilmaz, Deniz; Virtue, Sam; Xu, Xiaojun; Tan, Chong Yew; Griffin, Julian L.; Miller, Aubry K.; Vidal-Puig, Antonio; Teleman, Aurelio A.
    Mitochondria are involved in a variety of cellular functions, including ATP production, amino acid and lipid biogenesis and breakdown, signalling and apoptosis1,2,3. Mitochondrial dysfunction has been linked to neurodegenerative diseases, cancer and ageing4. Although transcriptional mechanisms that regulate mitochondrial abundance are known5, comparatively little is known about how mitochondrial function is regulated. Here we identify the metabolite stearic acid (C18:0) and human transferrin receptor 1 (TFR1; also known as TFRC) as mitochondrial regulators. We elucidate a signalling pathway whereby C18:0 stearoylates TFR1, thereby inhibiting its activation of JNK signalling. This leads to reduced ubiquitination of mitofusin via HUWE1, thereby promoting...

  6. Reactivation of multipotency by oncogenic PIK3CA induces breast tumour heterogeneity

    van Keymeulen, Alexandra; Lee, May Yin; Ousset, Marielle; Brohée, Sylvain; Rorive, Sandrine
    Breast cancer is the most frequent cancer in women and consists of heterogeneous types of tumours that are classified into different histological and molecular subtypes1,2. PIK3CA and P53 (also known as TP53) are the two most frequently mutated genes and are associated with different types of human breast cancers3. The cellular origin and the mechanisms leading to PIK3CA-induced tumour heterogeneity remain unknown. Here we used a genetic approach in mice to define the cellular origin of Pik3ca-derived tumours and the impact of mutations in this gene on tumour heterogeneity. Surprisingly, oncogenic Pik3caH1047R mutant expression at physiological levels4 in basal cells...

  7. Pik3cah1047r induces multipotency and multi-lineage mammary tumours.

    Koren, Shany; Reavie, Linsey B.; Pinto Couto, Joana; De Silva, Duvini; Stadler, Michael B.; Roloff, Tim
    The adult mouse mammary epithelium contains self-sustained cell lineages that form the inner luminal and outer basal cell layers, with stem and progenitor cells contributing to its proliferative and regenerative potential 1,2,3,4. A key issue in breast cancer biology is the effect of genomic lesions in specific mammary cell lineages on tumour heterogeneity and progression. The impact of transforming events on fate conversion in cancer cells of origin and thus their contribution to tumour heterogeneity remains largely elusive. Using in situ genetic lineage tracing and limiting dilution transplantation, we have unravelled the potential of PIK3CAH1047R, one of the most frequent...

  8. Mutations in DCHS1 cause mitral valve prolapse.

    Durst, Ronen; Sauls, Kimberly; Peal, David S.; deVlaming, Annemarieke; Toomer, Katelynn; Leyne, Maire
    Mitral valve prolapse (MVP) is a common cardiac valve disease that affects nearly 1 in 40 individuals 1,2,3. It can manifest as mitral regurgitation and is the leading indication for mitral valve surgery 4,5. Despite a clear heritable component, the genetic aetiology leading to non-syndromic MVP has remained elusive. Four affected individuals from a large multigenerational family segregating non-syndromic MVP underwent capture sequencing of the linked interval on chromosome 11. We report a missense mutation in the DCHS1 gene, the human homologue of the Drosophila cell polarity gene dachsous (ds), that segregates with MVP in the family. Morpholino knockdown of...

  9. Genetic evidence for two founding populations of the Americas.

    Skoglund, Pontus; Mallick, Swapan
    Genetic studies have consistently indicated a single common origin of Native American groups from Central and South America 1,2,3,4. However, some morphological studies have suggested a more complex picture, whereby the northeast Asian affinities of present-day Native Americans contrast with a distinctive morphology seen in some of the earliest American skeletons, which share traits with present-day Australasians (indigenous groups in Australia, Melanesia, and island Southeast Asia) 5,6,7,8. Here we analyse genome-wide data to show that some Amazonian Native Americans descend partly from a Native American founding population that carried ancestry more closely related to indigenous Australians, New Guineans and Andaman...

  10. Global exchange and accumulation of non-native plants

    van Kleunen, Mark; Dawson, Wayne; Essl, Franz; Pergl, Jan; Winter, Marten; Weber, Ewald; Kreft, Holger; Weigelt, Patrick
    All around the globe, humans have greatly altered the abiotic and biotic environment with ever-increasing speed. One defining feature of the Anthropocene epoch1,2 is the erosion of biogeographical barriers by human-mediated dispersal of species into new regions, where they can naturalize and cause ecological, economic and social damage3. So far, no comprehensive analysis of the global accumulation and exchange of alien plant species between continents has been performed, primarily because of a lack of data. Here we bridge this knowledge gap by using a unique global database on the occurrences of naturalized alien plant species in 481 mainland and 362...

  11. Broad plumes rooted at the base of the Earth's mantle beneath major hotspots

    French, Scott W.; Romanowicz, Barbara
    Plumes of hot upwelling rock rooted in the deep mantle have been proposed as a possible origin of hotspot volcanoes, but this idea is the subject of vigorous debate1,2. On the basis of geodynamic computations, plumes of purely thermal origin should comprise thin tails, only several hundred kilometres wide3, and be difficult to detect using standard seismic tomography techniques. Here we describe the use of a whole-mantle seismic imaging technique—combining accurate wavefield computations with information contained in whole seismic waveforms4—that reveals the presence of broad (not thin), quasi-vertical conduits beneath many prominent hotspots. These conduits extend from the core–mantle boundary...

  12. Global separation of plant transpiration from groundwater and streamflow

    Evaristo, Jaivime; Jasechko, Scott; McDonnell, Jeffrey J.
    Current land surface models assume that groundwater, streamflow and plant transpiration are all sourced and mediated by the same well mixed water reservoir—the soil. However, recent work in Oregon1 and Mexico2 has shown evidence of ecohydrological separation, whereby different subsurface compartmentalized pools of water supply either plant transpiration fluxes or the combined fluxes of groundwater and streamflow. These findings have not yet been widely tested. Here we use hydrogen and oxygen isotopic data (2H/1H ([delta]2H) and 18O/16O ([delta]18O)) from 47 globally distributed sites to show that ecohydrological separation is widespread across different biomes. Precipitation, stream water and groundwater from each...

  13. Alcohols as alkylating agents in heteroarene C–H functionalization

    Jin, Jian; MacMillan, David W. C.
    Redox processes and radical intermediates are found in many biochemical processes, including deoxyribonucleotide synthesis and oxidative DNA damage1. One of the core principles underlying DNA biosynthesis is the radical-mediated elimination of H2O to deoxygenate ribonucleotides, an example of ‘spin-centre shift’2, during which an alcohol C–O bond is cleaved, resulting in a carbon-centred radical intermediate. Although spin-centre shift is a well-understood biochemical process, it is underused by the synthetic organic chemistry community. We wondered whether it would be possible to take advantage of this naturally occurring process to accomplish mild, non-traditional alkylation reactions using alcohols as radical precursors. Because conventional radical-based...

  14. Guiding the folding pathway of dna origami

    Dunn, Katherine E.; Dannenberg, Frits; Ouldridge, Thomas E.; Kwiatkowska, Marta; Turberfield, Andrew J.; Bath, Jonathan
    DNA origami is a robust assembly technique that folds a single-stranded DNA template into a target structure by annealing it with hundreds of short ‘staple’ strands1,2,3,4. Its guiding design principle is that the target structure is the single most stable configuration5. The folding transition is cooperative4,6,7 and, as in the case of proteins, is governed by information encoded in the polymer sequence8,9,10,11. A typical origami folds primarily into the desired shape, but misfolded structures can kinetically trap the system and reduce the yield2. Although adjusting assembly conditions2,12 or following empirical design rules12,13 can improve yield, well-folded origami often need to...

  15. Negative refractive index and acoustic superlens from multiple scattering in single negative metamaterials

    Kaina, Nadège; Lemoult, Fabrice; Fink, Mathias; Lerosey, Geoffroy
    Metamaterials, man-made composite media structured on a scale much smaller than a wavelength, offer surprising possibilities for engineering the propagation of waves1,2,3,4,5,6. One of the most interesting of these is the ability to achieve superlensing—that is, to focus or image beyond the diffraction limit7. This originates from the left-handed behaviour—the property of refracting waves negatively—that is typical of negative index metamaterials8,9,10. Yet reaching this goal requires the design of ‘double negative’ metamaterials, which act simultaneously on the permittivity and permeability in electromagnetics11,12, or on the density and compressibility in acoustics; this generally implies the use of two different kinds of...

  16. Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system

    Drozdov, A. P.; Eremets, M.I.; Troyan, I. A.; Ksenofontov, V.; Shylin, S. I.
    A superconductor is a material that can conduct electricity without resistance below a superconducting transition temperature, Tc. The highest Tc that has been achieved to date is in the copper oxide system1: 133 kelvin at ambient pressure2 and 164 kelvin at high pressures3. As the nature of superconductivity in these materials is still not fully understood (they are not conventional superconductors), the prospects for achieving still higher transition temperatures by this route are not clear. In contrast, the Bardeen–Cooper–Schrieffer theory of conventional superconductivity gives a guide for achieving high Tc with no theoretical upper bound—all that is needed is a...

  17. Structural insights into the bacterial carbon–phosphorus lyase machinery

    Seweryn, Paulina; Van, Lan Bich; Kjeldgaard, Morten; Russo, Christopher J.; Passmore, Lori A.; Hove Jensen, Bjarne; Jochimsen, Bjarne; Brodersen, Ditlev E.
    Phosphorus is required for all life and microorganisms can extract it from their environment through several metabolic pathways. When phosphate is in limited supply, some bacteria are able to use phosphonate compounds, which require specialized enzymatic machinery to break the stable carbon–phosphorus (C–P) bond. Despite its importance, the details of how this machinery catabolizes phosphonates remain unknown. Here we determine the crystal structure of the 240-kilodalton Escherichia coli C–P lyase core complex (PhnG–PhnH–PhnI–PhnJ; PhnGHIJ), and show that it is a two-fold symmetric hetero-octamer comprising an intertwined network of subunits with unexpected self-homologies. It contains two potential active sites that probably...

  18. Architecture of the synaptotagmin–snare machinery for neuronal exocytosis

    Zhou, Qiangjun; Lai, Ying; Bacaj, Taulant; Zhao, Minglei; Lyubimov, Artem Y.; Uervirojnangkoorn, Monarin
    Synaptotagmin-1 and neuronal SNARE proteins have central roles in evoked synchronous neurotransmitter release; however, it is unknown how they cooperate to trigger synaptic vesicle fusion. Here we report atomic-resolution crystal structures of Ca2+- and Mg2+-bound complexes between synaptotagmin-1 and the neuronal SNARE complex, one of which was determined with diffraction data from an X-ray free-electron laser, leading to an atomic-resolution structure with accurate rotamer assignments for many side chains. The structures reveal several interfaces, including a large, specific, Ca2+-independent and conserved interface. Tests of this interface by mutagenesis suggest that it is essential for Ca2+-triggered neurotransmitter release in mouse hippocampal...

  19. The c9orf72 repeat expansion disrupts nucleocytoplasmic transport

    Zhang, Ke; Donnelly, Christopher J.; Haeusler, Aaron R.; Grima, Jonathan C.; Machamer, James B.; Steinwald, Peter
    The hexanucleotide repeat expansion (HRE) GGGGCC (G4C2) in C9orf72 is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Recent studies support an HRE RNA gain-of-function mechanism of neurotoxicity, and we previously identified protein interactors for the G4C2 RNA including RanGAP1. A candidate-based genetic screen in Drosophila expressing 30 G4C2 repeats identified RanGAP (Drosophila orthologue of human RanGAP1), a key regulator of nucleocytoplasmic transport, as a potent suppressor of neurodegeneration. Enhancing nuclear import or suppressing nuclear export of proteins also suppresses neurodegeneration. RanGAP physically interacts with HRE RNA and is mislocalized in HRE-expressing flies, neurons from...

  20. The quiet revolution of numerical weather prediction

    Bauer, Peter; Thorpe, Alan; Brunet, Gilbert
    Advances in numerical weather prediction represent a quiet revolution because they have resulted from a steady accumulation of scientific knowledge and technological advances over many years that, with only a few exceptions, have not been associated with the aura of fundamental physics breakthroughs. Nonetheless, the impact of numerical weather prediction is among the greatest of any area of physical science. As a computational problem, global weather prediction is comparable to the simulation of the human brain and of the evolution of the early Universe, and it is performed every day at major operational centres across the world.

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