1,326 research outputs found

    WIPI1 promotes fission of endosomal transport carriers and formation of autophagosomes through distinct mechanisms.

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    Autophagosome formation requires PROPPIN/WIPI proteins and monophosphorylated phosphoinositides, such as phosphatidylinositol-3-phosphate (PtdIns3P) or PtdIns5P. This process occurs in association with mammalian endosomes, where the PROPPIN WIPI1 has additional, undefined roles in vesicular traffic. To explore whether these functions are interconnected, we dissected routes and subreactions of endosomal trafficking requiring WIPI1. WIPI1 specifically acts in the formation and fission of tubulo-vesicular endosomal transport carriers. This activity supports the PtdIns(3,5)P <sub>2</sub> -dependent transport of endosomal cargo toward the plasma membrane, Golgi, and lysosomes, suggesting a general role of WIPI1 in endosomal protein exit. Three features differentiate the endosomal and macroautophagic/autophagic activities of WIPI1: phosphoinositide binding site II, the requirement for PtdIns(3,5)P <sub>2</sub> , and bilayer deformation through a conserved amphipathic α-helix. Their inactivation preserves autophagy but leads to a strong enlargement of endosomes, which accumulate micrometer-long endosomal membrane tubules carrying cargo proteins. WIPI1 thus supports autophagy and protein exit from endosomes by different modes of action. We propose that the type of phosphoinositides occupying its two lipid binding sites, the most unusual feature of PROPPIN/WIPI family proteins, switches between these effector functions.Abbreviations: EGF: epidermal growth factorEGFR: epidermal growth factor receptorKD: knockdownKO: knockoutPtdIns3P: phosphatidylinositol-3-phosphatePtdIns5P: phosphatidylinositol-5-phosphatePtdIns(3,5)P <sub>2</sub> : phosphatidylinositol-3,5-bisphosphateTF: transferrinTFRC: transferrin receptorWT: wildtype

    Diffractive rho-meson Leptoproduction on Polarized Nucleon as a Way to Measure the Polarized Gluon Distribution

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    The amplitude of diffractive ρ\rho (and open quark) leptoproduction on a polarized target is calculated in the leading log approximation of pQCD using the hadron-parton duality hypothesis. The spin-spin asymmetry is expressed in terms of the spin dependent gluon and quark structure functions in the small xx region. Therefore the γ+pρ+p\gamma^*+p\to \rho +p reaction provides a promising tool to study the spin dependent gluon distribution ΔG(x,q2)\Delta G(x,q^2).Comment: 13 pages, LaTeX, 2 figure

    Spin Asymmetries In Diffractive J/ΨJ/\Psi Leptoproduction

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    In this report we calculate the cross section and AllA_{ll} asymmetry for the diffractive J/ΨJ/\Psi leptoproduction. We study dependences of the asymmetry on the structure of the Pomeron-proton couplingComment: 4 pages, latex, two PS figures, presented at the International Workshop "Symmetry and Spin" PRAHA'9

    Effects of color superconductivity on the structure and formation of compact stars

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    We show that if color superconducting quark matter forms in hybrid or quark stars it is possible to satisfy most of recent observational boundaries on masses and radii of compact stellar objects. An energy of the order of 105310^{53} erg is released in the conversion from a (metastable) hadronic star into a (stable) hybrid or quark star in presence of a color superconducting phase. If the conversion occurs immediately after the deleptonization of the proto-neutron star, the released energy can help Supernovae to explode. If the conversion is delayed the energy released can power a Gamma Ray Burst. A delay between the Supernova and the subsequent Gamma Ray Burst is possible, in agreement with the delay proposed in recent analysis of astrophysical data.Comment: 4 pages, 2 figures. To be published in Phys.Rev.

    Dilepton-tagged jets in relativistic nucleus-nucleus collisions: A case study

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    We study the A+B -> l+ l- + jet +X process in nucleus-nucleus collisions at relativistic energies. The dilepton as well as the jet will pass through the matter produced in such collisions. The recoiling dilepton will carry information about the kinematical features of the jet, and will thus prove to be a very effective tool in isolating in-medium effects such as energy-loss and fragmentation function modifications. We estimate the contributions due to correlated charm and bottom decay and we identify a window where they are small as compared to pairs from the NLO Drell-Yan process.Comment: 7 pages, 9 figures Two figures modified, references adde

    The resummation of inter-jet energy flow for gaps-between-jets processes at HERA

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    We calculate resummed perturbative predictions for gaps-between-jets processes and compare to HERA data. Our calculation of this non-global observable needs to include the effects of primary gluon emission (global logarithms) and secondary gluon emission (non-global logarithms) to be correct at the leading logarithm (LL) level. We include primary emission by calculating anomalous dimension matrices for the geometry of the specific event definitions and estimate the effect of non-global logarithms in the large NcN_c limit. The resulting predictions for energy flow observables are consistent with experimental data.Comment: 31 pages, 4 figures, 2 table

    Reduction of the Three Dimensional Schrodinger Equation for Multilayered Films

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    In this paper, we present a method for reducing the three dimensional Schrodinger equation to study confined metallic states, such as quantum well states, in a multilayer film geometry. While discussing some approximations that are employed when dealing with the three dimensionality of the problem, we derive a one dimensional equation suitable for studying such states using an envelope function approach. Some applications to the Cu/Co multilayer system with regard to spin tunneling/rotations and angle resolved photoemission are discussed.Comment: 14 pages, 1 figur

    Does efficiency help banks survive and thrive during financial crises?

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    We examine how bank efficiency during normal times affects survival, risk, and profitability during subsequent financial crises using data from five U.S. financial crises and preceding normal times. We find that cost efficiency during normal times helps reduce bank failure probabilities, decrease risk, and enhance profitability during subsequent financial crises, while profit efficiency has limited benefits. Results suggest that cost efficiency better measures management quality, while profit efficiency may partially reflect temporary high returns from risky investments during normal times. Findings have policy implications and imply that improving bank cost efficiency during normal times may promote better financial crisis performance

    CCN1 mutation is associated with atrial septal defect

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    The genetic basis of congenital heart disease remains unknown in most of the cases. Recently, a novel mouse model shed new light on the role of CCN1/CYR61, a matricellular regulatory factor, in cardiac morphogenesis. In a candidate gene approach, we analyzed a cohort of 143 patients with atrial septal defects (ASD) by sequencing the coding exons of CCN1. In addition to three frequent polymorphisms, we identified an extremely rare novel heterozygous missense mutation (c.139C > T; p.R47W) in one patient with severe ASD. The mutation leads to an exchange of residues with quite different properties in a highly conserved position of the N-terminal insulin-like growth factor binding protein module. Further bioinformatic analysis, exclusion of known ASD disease genes as well as the exclusion of the mutation in a very high number of ethnically matched controls (more than 1,000 individuals) and in public genetic databases, indicates that the p.R47W variant is a probable disease-associated mutation. The report about ASD in mice in heterozygous Ccn 1 +/- animals strongly supports this notion. Our study is the first to suggest a relationship between a probable CCN1 mutation and ASD. Our purpose here was to draw attention to CCN1, a gene that we believe may be important for genetic analysis in patients with congenital heart disease
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