506 research outputs found

    3D kinematics of the near-IR HH 223 outflow in L723

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    In this work, we derive the full 3D kinematics of the near-infrared outflow HH 223, located in the dark cloud Lynds 723 (L723), where a well-defined quadrupolar CO outflow is found. HH 223 appears projected on to the two lobes of the eastwest CO outflow. The radio continuum source VLA 2, towards the centre of the CO outflow, harbours a multiple system of low-mass young stellar objects. One of the components has been proposed to be the exciting source of the eastwest CO outflow. From the analysis of the kinematics, we get further evidence on the relationship between the near-infrared and CO outflows and on the location of their exciting source. The proper motions were derived using multi-epoch, narrow-band H2 (2.122 μm line) images. Radial velocities were derived from the 2.122 μm line of the spectra. Because of the extended (∼5 arcmin), S-shaped morphology of the target, the spectra were obtained with the multi-object-spectroscopy (MOS) observing mode using the instrument Long-Slit Intermediate Resolution Infrared Spectrograph (LIRIS) at the 4.2 m William Herschel Telescope. To our knowledge, this work is the first time that MOS observing mode has been successfully used in the near-infrared range for an extended target

    Structural insights into the synthesis of FMN in prokaryotic organisms

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    Riboflavin kinases (RFKs) catalyse the phosphorylation of riboflavin to produce FMN. In most bacteria this activity is catalysed by the C-terminal module of a bifunctional enzyme, FAD synthetase (FADS), which also catalyses the transformation of FMN into FAD through its N-terminal FMN adenylyl transferase (FMNAT) module. The RFK module of FADS is a homologue of eukaryotic monofunctional RFKs, while the FMNAT module lacks homologyto eukaryotic enzymes involved in FAD production. Previously, the crystal structure of Corynebacterium ammoniagenes FADS (CaFADS) was determined in its apo form. This structure predicted a dimer-of-trimers organization with the catalytic sites of two modules of neighbouring protomers approaching each other, leading to a hypothesis about the possibility of FMN channelling in the oligomeric protein. Here, two crystal structures of the individually expressed RFK module of CaFADS in complex with the products of the reaction, FMN and ADP, are presented. Structures are complemented with computational simulations, binding studies and kinetic characterization. Binding of ligands triggers dramatic structural changes in the RFK module, which affect large portions of the protein. Substrate inhibition and molecular-dynamics simulations allowed the conformational changes that take place along the RFK catalytic cycle to be established. The influence of these conformational changes in the FMNAT module is also discussed in the context of the full-length CaFADS protomer and the quaternary organization.This work has been supported by MINECO, Spain (BIO2013-42978-P to MM and BFU2014-59389-P to JAH), the Aragonian Government-FEDER (B18), Autonomous Community of Madrid (S2010/BMD-2457), Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS) and Universidad Industrial de Santander (project 1818 to IL).Peer Reviewe

    The crystal structure of Canavalia brasiliensis lectin suggests a correlation between its quaternary conformation and its distinct biological properties from Concanavalin A

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    AbstractCanavalia brasiliensis lectin was isolated from the seeds of a Brazilian autochthonous Leguminosae plant. Despite extensive amino acid sequence similarity with Concanavalin A, C. brasiliensis lectin exerts in vitro and in vivo cellular effects that are markedly different from those displayed by Concanavalin A. We have solved the crystal structure of the C. brasiliensis lectin at 3.0 Å resolution. The three-dimensional structure of the lectin monomer can be superimposed onto that of Concanavalin A with a root-mean-square deviation for all Cα atoms of 0.65 Å. However, this parameter is 0.84 and 1.62 Å when the C. brasiliensis lectin dimer and tetramer, respectively, are compared with the same structures of Concanavalin A. We suggest that these differences in quaternary structure may account for the different biological properties of these two highly related Leguminosae lectins.© 1997 Federation of European Biochemical Societies

    Critical Micronutrients in Pregnancy, Lactation, and Infancy: Considerations on Vitamin D, Folic Acid, and Iron, and Priorities for Future Research

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    The Early Nutrition Academy and the European Commission-funded EURRECA Network of Excellence jointly sponsored a scientific workshop on critical micronutrients in pregnancy, lactation, and infancy. Current knowledge and unresolved questions on the supply of vitamin D, folic acid, and iron for pregnant women, lactating women, and infants, and their health effects were discussed. The question was addressed of whether, and under which circumstances, supplementation with these micronutrients in addition to usual dietary intakes is advisable. The workshop participants concluded that public health strategies for improving supplementation with these micronutrients in pregnancy, lactation, and infancy are required. Further research priorities should focus on adequately powered human intervention trials to obtain a stronger evidence base for the amounts of vitamin D, folic acid, and iron that have optimal effects on health. The conclusions of the workshop should help to inform the scientific community as well as public health policy strategies. Copyright (C) 2011 S. Karger AG, Base

    Repression of DNA-binding dependent glucocorticoid receptor-mediated gene expression

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    The glucocorticoid receptor (GR) affects the transcription of genes involved in diverse processes, including energy metabolism and the immune response, through DNA-binding dependent and independent mechanisms. The DNA-binding dependent mechanism occurs by direct binding of GR to glucocorticoid response elements (GREs) at regulatory regions of target genes. The DNA-binding independent mechanism involves binding of GR to transcription factors and coactivators that, in turn, contact DNA. A small molecule that competes with GR for binding to GREs could be expected to affect the DNA-dependent pathway selectively by interfering with the protein-DNA interface. We show that a DNA-binding polyamide that targets the consensus GRE sequence binds the glucocorticoid-induced zipper (GILZ) GRE, inhibits expression of GILZ and several other known GR target genes, and reduces GR occupancy at the GILZ promoter. Genome-wide expression analysis of the effects of this polyamide on a set of glucocorticoid-induced and -repressed genes could help to elucidate the mechanism of GR regulation for these genes

    Eureka Role Playing Game: An Instructional Tool In Improving The Proficiency Level In Chemistry 7

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    The Eureka Role Playing Game is a game-based instructional tool for learning science concepts. The study aimed to improve proficiency level of the learners in Science 7 particularly in Chemistry subject. This study utilized a Quantitative Method to measure the gathered data and test the hypothesis. Quasi-experimental pretest-posttest research design was also used with a validated questionnaire and Eureka Role-Playing Game (RPG) as the primary data gathering instrument to evaluate students’ proficiency level improvement as the intervention was administered to experimental group and traditional teaching method for controlled group. Results showed that in the controlled group, the mean post-test result was higher than the mean pre-test result, but still at the beginning level of proficiency. Meanwhile, the mean post-test result of the experimental group is higher compared to the mean pre-test result. Therefore, the level of proficiency of the experimental group has improved from a beginning level to a developing level after the intervention. A significant difference in the pre-test and post-test between the experimental group and the control group is in favor of the experimental group. Therefore, the alternative hypotheses of this study are accepted. Evaluated by the Science experts, the instructional tool passed the curricular validity criteria. The researchers recommend the use of Eureka Role Playing Game since it significantly increased the proficiency level of the students from beginning to developing level based on the findings

    Efficacy of edelfosine lipid nanoparticles in breast cancer cells

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    Breast cancer is a heterogeneous group of neoplasms predominantly originating in the terminal duct lobular units. It represents the leading cause of cancer death in women and the survival frequencies for patients at advanced stages of the disease remain low. New treatment options need to be researched to improve these rates. The anti-tumor ether lipid edelfosine (ET) is the prototype of a novel generation of promising anticancer drugs. However, it presents several drawbacks for its use in cancer therapy, including gastrointestinal and hemolytic toxicity and low oral bioavailability. To overcome these obstacles, ET was encapsulated in Precirol ATO 5 lipid nanoparticles (ET-LN), and its anti-tumor potential was in vitro tested in breast cancer. The formulated ET-LN were more effective in inhibiting cell proliferation and notably decreased cell viability, showing that the cytotoxic effect of ET was considerably enhanced when ET was encapsulated. In addition, ET and ET-LN were able to promote cell cycle arrest at G1 phase. Moreover, although both treatments provoked an apoptotic effect in a time-dependent manner, such anti-tumor effects were noticeably improved with ET-LN treatment. Therefore, our results indicate that encapsulating ET in LN played an essential role in improving the efficacy of the drug

    Restricted by borders: trade-offs in transboundary conservation planning for large river systems

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    Effective conservation of freshwater biodiversity requires accounting for connectivity and the propagation of threats along river networks. With this in mind, the selection of areas to conserve freshwater biodiversity is challenging when rivers cross multiple jurisdictional boundaries. We used systematic conservation planning to identify priority conservation areas for freshwater fish conservation in Hungary (Central Europe). We evaluated the importance of transboundary rivers to achieve conservation goals by systematically deleting some rivers from the prioritization procedure in Marxan and assessing the trade-offs between complexity of conservation recommendations (e.g., conservation areas located exclusively within Hungary vs. transboundary) and cost (area required). We found that including the segments of the largest transboundary rivers (i.e. Danube, Tisza) in the area selection procedure yielded smaller total area compared with the scenarios which considered only smaller national and transboundary rivers. However, analyses which did not consider these large river segments still showed that fish diversity in Hungary can be effectively protected within the country’s borders in a relatively small total area (less than 20 % of the country’s size). Since the protection of large river segments is an unfeasible task, we suggest that transboundary cooperation should focus on the protection of highland riverine habitats (especially Dráva and Ipoly Rivers) and their valuable fish fauna, in addition to the protection of smaller national rivers and streams. Our approach highlights the necessity of examining different options for selecting priority areas for conservation in countries where transboundary river systems form the major part of water resources.Full Tex

    Safeguarding freshwater life beyond 2020: Recommendations for the new global biodiversity framework from the European experience

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    Plans are currently being drafted for the next decade of action on biodiversity-both the post-2020 Global Biodiversity Framework of the Convention on Biological Diversity (CBD) and Biodiversity Strategy of the European Union (EU). Freshwater biodiversity is disproportionately threatened and underprioritized relative to the marine and terrestrial biota, despite supporting a richness of species and ecosystems with their own intrinsic value and providing multiple essential ecosystem services. Future policies and strategies must have a greater focus on the unique ecology of freshwater life and its multiple threats, and now is a critical time to reflect on how this may be achieved. We identify priority topics including environmental flows, water quality, invasive species, integrated water resources management, strategic conservation planning, and emerging technologies for freshwater ecosystem monitoring. We synthesize these topics with decades of first-hand experience and recent literature into 14 special recommendations for global freshwater biodiversity conservation based on the successes and setbacks of European policy, management, and research. Applying and following these recommendations will inform and enhance the ability of global and European post-2020 biodiversity agreements to halt and reverse the rapid global decline of freshwater biodiversity

    Reaction products and the X-ray structure of AmpDh2, a virulence determinant of Pseudomonas aeruginosa

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    4 pags, 4 figs. -- Supporting Information is available at the Publisher web.The zinc protease AmpDh2 is a virulence determinant of Pseudomonas aeruginosa, a problematic human pathogen. The mechanism of how the protease manifests virulence is not known, but it is known that it turns over the bacterial cell wall. The reaction of AmpDh2 with the cell wall was investigated, and nine distinct turnover products were characterized by LC/MS/MS. The enzyme turns over both the cross-linked and noncross-linked cell wall. Three high-resolution X-ray structures, the apo enzyme and two complexes with turnover products, were solved. The X-ray structures show how the dimeric protein interacts with the inner leaflet of the bacterial outer membrane and that the two monomers provide a more expansive surface for recognition of the cell wall. This binding surface can accommodate the 3D solution structure of the cross-linked cell wall. © 2013 American Chemical Society.This work was supported by a grant from the NIH (GM61629) and by grants BFU2011-25326 (the Spanish Ministry of Economy and Competitiveness) and S2010/BMD-2457 (the Government of Community of Madrid). The Mass Spectrometry & Proteomics Facility of the University of Notre Dame is supported by grant CHE0741793 from the NSF
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