75 research outputs found

    Parallel Germline Infiltration of a Lentivirus in Two Malagasy Lemurs

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    Retroviruses normally infect the somatic cells of their host and are transmitted horizontally, i.e., in an exogenous way. Occasionally, however, some retroviruses can also infect and integrate into the genome of germ cells, which may allow for their vertical inheritance and fixation in a given species; a process known as endogenization. Lentiviruses, a group of mammalian retroviruses that includes HIV, are known to infect primates, ruminants, horses, and cats. Unlike many other retroviruses, these viruses have not been demonstrably successful at germline infiltration. Here, we report on the discovery of endogenous lentiviral insertions in seven species of Malagasy lemurs from two different genera—Cheirogaleus and Microcebus. Combining molecular clock analyses and cross-species screening of orthologous insertions, we show that the presence of this endogenous lentivirus in six species of Microcebus is the result of one endogenization event that occurred about 4.2 million years ago. In addition, we demonstrate that this lentivirus independently infiltrated the germline of Cheirogaleus and that the two endogenization events occurred quasi-simultaneously. Using multiple proviral copies, we derive and characterize an apparently full length and intact consensus for this lentivirus. These results provide evidence that lentiviruses have repeatedly infiltrated the germline of prosimian species and that primates have been exposed to lentiviruses for a much longer time than what can be inferred based on sequence comparison of circulating lentiviruses. The study sets the stage for an unprecedented opportunity to reconstruct an ancestral primate lentivirus and thereby advance our knowledge of host–virus interactions

    Potential of Core-Collapse Supernova Neutrino Detection at JUNO

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    JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

    Detection of the Diffuse Supernova Neutrino Background with JUNO

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    As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

    Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

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    Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30MM_{\odot} for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

    Analyse sémantique AMR pour le français par transfert translingue

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    International audienceMeaning Representation (AMR) est un formalisme permettant de représenter la sémantique d'une phrase sous la forme d'un graphe, dont les nœuds sont des concepts sémantiques et les arcs des relations typées. Dans ce travail, nous construisons un analyseur AMR pour le français en étendant une méthode translingue zéro-ressource proposée par Procopio et al. (2021). Nous comparons l'utilisation d'un transfert bilingue à un transfert multi-cibles pour l'analyse sémantique AMR translingue. Nous construisons également des données d'évaluation pour l'AMR français. Nous présentons enfin les premiers résultats d'analyse AMR automatique pour le français. Selon le jeu de test utilisé, notre parseur AMR entraîné de manière zéro-ressource, c'est-à-dire sans données d'entraînement, obtient des scores Smatch qui se situent entre 54,2 et 66,0

    Birbeck granule-like "organized smooth endoplasmic reticulum" resulting from the expression of a cytoplasmic YFP-tagged langerin.

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    Langerin is required for the biogenesis of Birbeck granules (BGs), the characteristic organelles of Langerhans cells. We previously used a Langerin-YFP fusion protein having a C-terminal luminal YFP tag to dynamically decipher the molecular and cellular processes which accompany the traffic of Langerin. In order to elucidate the interactions of Langerin with its trafficking effectors and their structural impact on the biogenesis of BGs, we generated a YFP-Langerin chimera with an N-terminal, cytosolic YFP tag. This latter fusion protein induced the formation of YFP-positive large puncta. Live cell imaging coupled to a fluorescence recovery after photobleaching approach showed that this coalescence of proteins in newly formed compartments was static. In contrast, the YFP-positive structures present in the pericentriolar region of cells expressing Langerin-YFP chimera, displayed fluorescent recovery characteristics compatible with active membrane exchanges. Using correlative light-electron microscopy we showed that the coalescent structures represented highly organized stacks of membranes with a pentalaminar architecture typical of BGs. Continuities between these organelles and the rough endoplasmic reticulum allowed us to identify the stacks of membranes as a form of "Organized Smooth Endoplasmic Reticulum" (OSER), with distinct molecular and physiological properties. The involvement of homotypic interactions between cytoplasmic YFP molecules was demonstrated using an A206K variant of YFP, which restored most of the Langerin traffic and BG characteristics observed in Langerhans cells. Mutation of the carbohydrate recognition domain also blocked the formation of OSER. Hence, a "double-lock" mechanism governs the behavior of YFP-Langerin, where asymmetric homodimerization of the YFP tag and homotypic interactions between the lectin domains of Langerin molecules participate in its retention and the subsequent formation of BG-like OSER. These observations confirm that BG-like structures appear wherever Langerin accumulates and confirm that membrane trafficking effectors dictate their physiology and, illustrate the importance of molecular interactions in the architecture of intracellular membranes

    Interdisciplinarités : rencontres entre les disciplines, enjeux, dispositifs, freins et leviers

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    Dans un contexte où les problématiques et les pratiques de recherche académique bousculent les frontières disciplinaires et où les institutions scolaires prônent l’interdisciplinarité et multiplient les dispositifs interdisciplinaires, ce numéro se propose de présenter l’actualité de la recherche en didactique des sciences et des technologies sur la question des rencontres entre les disciplines. Après une première partie développant les évolutions de la recherche académique et de l’institution scolaire, l’article d’introduction montre comment la question de l’interdisciplinarité, la manière dont on envisage les liens entre les disciplines sont liées aux finalités attribuées à l’enseignement des sciences, avec deux orientations contrastées mais non contradictoires potentielles, celle d’une orientation de formation épistémologique et celle d’une orientation de formation citoyenne. Les contributions de la partie thématique du dossier se positionnent différemment sur ces deux orientations quant aux enjeux attribués à l’enseignement des sciences, en lien avec les enjeux de l’interdisciplinarité. Ils articulent des réflexions épistémologiques et des analyses de dispositifs interdisciplinaires en classe et en formation des enseignants. In a context where academic research issues and practices are shaking up the boundaries between disciplines and where educational institutions promote interdisciplinarity and multiply interdisciplinary devices, this issue aims to present current research in science and technology teaching concerning the confluence of disciplines. After a first part developing the evolutions of academic research and of the scholar institution, the introductory article shows how the issue of interdisciplinarity, the way in which the links between disciplines are seen, are linked to the aims assigned to science education, with two contrasting but not conflicting potential orientations for training : an epistemological and a citizen orientation. The contributions of the thematic section of the review take different positions on these two orientations regarding the aims assigned to science teaching and in relation to the aims of interdisciplinarity. They articulate epistemological reflections and analyses of interdisciplinary devices in classroom and teacher training

    FRAP analysis of the mobilities of Langerin/YFP chimeras.

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    <p>(A) Selected regions of M10 cells stably expressing either Lang-YFP (upper panels) or YFP-Lang (middle and lower panels) were bleached (arrows) and the fluorescence in single z-sections was recorded approximately every 1.6 s. (B) The fluorescence in the bleached area was quantified and plotted against time after correction for the change in total fluorescence. At least 10 cells were analyzed for each plot; error bars indicate the standard error of the mean. F<sub>i</sub> and F<sub>m</sub> designate the immobile and mobile fractions of the Langerin/YFP chimeras, respectively.</p

    Continuity of the BG-like structures with the rough ER.

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    <p>Transfected M10 cells stably expressing YFP-Lang were processed for electron microscopy. M10 cells stably expressing YFP-Lang were processed for FIB/SEM. The surface of the block was ion-milled and serial images were acquired. A 3D reconstruction was then obtained from the image stack after manual segmentation. (A) A stack of BG-like membranes and sacs of the rough ER in the same plane with (B) manual segmentation of the different objects of interest. The BG-like structures appear in orange, yellow and red and the ER in green. (C and D) A 3D reconstruction demonstrating that continuity (blue segments) exists between the BG-like membranes and the ER (two different angles of view, see also <b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060813#pone.0060813.s007" target="_blank">Video S1</a></b>). Scale bars: 500 nm.</p
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