361 research outputs found
Antibacterial activity and pore-forming properties of ceratotoxins: a mechanism of action based on the barrel stave model.
No full textCeratotoxins are a-helical cationic peptides isolated from the medfly Ceratitis capitata. These amphipathic peptides were found to display strong antibacterial activity and weak hemolytic activity. When reconstituted into planar lipid bilayers, ceratotoxins developed highly asymmetric I/V curves under voltage ramps and formed, in single-channel experiments, well-defined voltage-dependent ion channels according to the barrel stave model. The antibacterial activity and pore-forming properties of these molecules were well correlated. Similar experiments performed with synthesized truncated fragments showed that the C-terminal domain of ceratotoxins, is strongly implicated in the formation of helical bundles in the membrane whereas the largely cationic N-terminal region is likely to anchor ceratotoxins on the lipid surface
Direct Interaction Between the Rice yellow mottle virus (RYMV) VPg and the Central Domain of the Rice eIF(iso)4G1 Factor Correlates with Rice Susceptibility and RYMV Virulence
No full textWave-front phase retrieval in transmission electron microscopy via ptychography
No full textThere are many different strategies that allow the solving of the well-known phase problem corresponding to the loss of phase information during a physical measurement. In microscopy, and, in particular, in transmission electron microscopy, most of these strategies focus on the retrieval of high-resolution information with the importance of lower resolution data often overlooked. Ptychography offers a means to investigate such data. Ptychography is a robust diffractive imaging technique with fast convergence for phase retrieval but, until now, has not been applied at the nanoscale. In this paper, we use the ptychographical iterative engine to retrieve the phase change at the exit plane of metallic nanoparticles using a conventional transmission electron microscope. Ptychographical reconstructions yielded images with a phase resolution of π/10 and a spatial resolution of 1 nm. These results stand as a first step toward aberration-free lensless imaging. The technique lends itself to be an alternative to off-axis electron holography or focal series reconstructio
La cosmétologie à travers les âges
No full textDie Kosmetologie im Laufe der Zeit.
Die Verfasserin gibt eine kurze Übersicht der Kosmetologie vom alten Aegypten an bis zum 19. Jahrhundert.Cosmetology across the ages.
The author paints a quick sketch of cosmetology from Ancient Egypt to the 19th century.de Roeck-Holtzhauer Yannick. La cosmétologie à travers les âges. In: Revue d'histoire de la pharmacie, 76ᵉ année, n°279, 1988. pp. 397-399
Révisions transatlantiques : une expérience de télécollaboration entre l’Université Ca’ Foscari et Bentley University
No full textThe aim of this work is to present the ins and outs of a telecollaboration project between an American university (Bentley University) and Ca\u27 Foscari University. This project targets oral production and revision skills around an authentic language object, the video CV. Between March and April 2021, the author and a colleague from Bentley University set up a collaborative video CV revision project between 10 American FLE students and 13 students from Ca\u27 Foscari University of Venice, Italy (CEFR level B1-B2 for both groups). After a preparation phase started in December 2020 on both sides of the Atlantic, the device was implemented with work phases in synchronous and asynchronous modality. First, we will provide a theoretical framework concerning the use of telecollaboration mediated by computer for didactics of French as a foreign language. Then, we will go into more detail on the organisation, the setting up of the project and the modalities, the course of the exchanges and the tools used. Finally, we will present the first results obtained through this project and raise some issues about some negative outcomes.L’objectif de ce travail est d’exposer les tenants et aboutissants d’un projet de télécollaboration entre une université américaine (Bentley University) et l’université Ca’ Foscari de Venise. Ce projet vise les compétences de production et de révision orales autour d’un objet langagier authentique, le CV vidéo. Entre Mars et Avril 2021 compris, l’auteur et une collègue de l’université américaine de la Bentley University ont mis en place un projet de révision collaborative de curriculum vitae au format vidéo entre 10 étudiant.es de FLE américains et 13 étudiant.es de l’université Ca’ Foscari (niveau B1-B2 du CECRL). Après une phase de préparation engagée dès décembre 2020 des deux côtés de l’Atlantique, le dispositif a été mis en œuvre avec des phases de travail en modalité synchrone et asynchrone. Dans un premier temps, nous fournirons un cadre théorique concernant le recours à la télécollaboration médiée par ordinateur en didactique du Français Langue Etrangère. Ensuite, nous reviendrons plus en détail sur l’organisation, la mise en place du projet et les modalités, le déroulement des échanges et les outils utilisés. Nous présenterons enfin les premiers résultats obtenus par le biais de ce projet et soulèverons les problématiques qui ressortent de résultats mitigés
Law & Economics Perspectives on Electricity Regulation
No full textThis paper first reviews some of the main contributions of the new institutional economics to the analysis of the process of competitive transformation of network industries. It shows that neoinstitutional analysis is complementary to the microeconomics of rational pricing, since it accounts for the decisive role of an institutional framework adapted to new transactions. It emphasizes the importance of the political reform process, which draws on the conditions of attractiveness and feasibility to define an initial reorganization of property rights in these industries. The paper then analyzes in this light some of the main challenges ahead for electricity regulation: the question of investment in generation capacities and the link to long term contracts, the regulation of wholesale market power, the support to Renewable Energy Sources for Electricity (RES-E) and the design of new regulatory authorities.Electricity Markets; New Institutional Economics; Law & Economics
« Notte pour faire la pomade pour plusieurs maux » ou la recette d'un guérisseur vendéen
No full text« Notiz zur Bereitung der Salbe für mehrere Gebrechen » oder das Rezept eines Heilkunstlers aus der Vendée.
Der Verfasser untersucht die Zusammensetzung der Formel eines Empirikers aus der Vendée in der zweiten Hälfte des 19. Jahrhunderts fur Flechten, Brandwunden, Frostbeulen und Hamorrhoiden. Er ziecht daraus den Schluss auf Stichhaltigkeit dieser Formel welche der damaligen gebrauchten Polytherapie entspricht.« Notes on How to Make the Pommade for Several Illnesses » or the recipe of a healer from Vendée.
The author examines the composition of a formula from an empiric of Vendée, from the second half of the 19th century, for skin eruptions, burns, chilblains and hemorrhoids. He concludes that the components of the formula are valid, and conform to the polytherapy in use at that time.Romieux Yannick. « Notte pour faire la pomade pour plusieurs maux » ou la recette d'un guérisseur vendéen. In: Revue d'histoire de la pharmacie, 78ᵉ année, n°287, 1990. pp. 449-452
Unique Features of the Folding Landscape of a Repeat Protein Revealed by Pressure Perturbation
No full textThe volumetric properties of proteins yield information about the changes in packing and hydration between various states along the folding reaction coordinate and are also intimately linked to the energetics and dynamics of these conformations. These volumetric characteristics can be accessed via pressure perturbation methods. In this work, we report high-pressure unfolding studies of the ankyrin domain of the Notch receptor (Nank1-7) using fluorescence, small-angle x-ray scattering, and Fourier transform infrared spectroscopy. Both equilibrium and pressure-jump kinetic fluorescence experiments were consistent with a simple two-state folding/unfolding transition under pressure, with a rather small volume change for unfolding compared to proteins of similar molecular weight. High-pressure fluorescence, Fourier transform infrared spectroscopy, and small-angle x-ray scattering measurements revealed that increasing urea over a very small range leads to a more expanded pressure unfolded state with a significant decrease in helical content. These observations underscore the conformational diversity of the unfolded-state basin. The temperature dependence of pressure-jump fluorescence relaxation measurements demonstrated that at low temperatures, the folding transition state ensemble (TSE) lies close in volume to the folded state, consistent with significant dehydration at the barrier. In contrast, the thermal expansivity of the TSE was found to be equivalent to that of the unfolded state, indicating that the interactions that constrain the folded-state thermal expansivity have not been established at the folding barrier. This behavior reveals a high degree of plasticity of the TSE of Nank1-7
Toucher au plus vivant. Poétique et politique de l’amour dans 'Je cherche l’Italie' de Yannick Haenel
No full textÀ travers une lecture du roman 'Je cherche l’Italie' (2015) de Yannick Haenel est soulignée la manière toute singulière suivant laquelle la littérature (le poétique) permet d’étendre la compréhension que l’on se fait habituellement du politique, la plupart du temps réduit à une lutte pour la conquête d’un pouvoir de l’État ou dans l’État, à l’organisation des pouvoirs ou à un art/exercice de gouverner. Il s’agit ainsi de mettre en lumière la façon dont l’écrivain français, par son récit, fait de l’amour, qui a été peu à peu relégué au cercle intime, le cœur d’une possible reconfiguration du politique au sein de la société occidentale contemporaine en crise(s) et comment Haenel établit l’amour en tant que principe politique solide et déterminant pouvant venir revitaliser voire restructurer anarchiquement le vivre ensemble.Throughout a focused reading of Yannick Haenel’s novel Je cherche l’Italie (2015) is underlined the incongruous ability of literature (the poetics) to extend usual understanding of politics, which is often reduced to a conquest of power by the State or in the State, the organization of power(s) or the art (practice) of governing. This article aims to highlight the way the French author puts love, which was gradually relegated to the intimate sphere, at the heart of a possible reconfiguration of politics in the crisis-stricken contemporary western society. It shows how Haenel establishes love as a strong and decisive political principle that could revitalize or even restructure anarchically the vivre ensemble
Caractérisation et production de protéines impliquées dans le système de défense " inné " des poissons
No full textLe mucus épidermique de poisson contient de nombreux composés lui conférant un rôle de protection contre les microorganismes. Récemment plusieurs protéines antibactériennes ont été isolées des fractions hydrophobes des mucus épidermiques d'anguille, de tanche et de truite. Ces protéines possédaient une forte activité antibactérienne corrélée à une activité "formeur" de pores, responsable de la perméabilisation des membranes bactériennes. La première partie de ce travail a consisté à montrer que de telles protéines étaient présentes dans le mucus d'un poisson d'eau de mer. A partir du mucus de turbot une protéine de 55 kDa, possédant de telles activités, a été isolée et caractérisée. Dans la seconde partie de cette étude, nous nous sommes intéressés à la protéine de 65 kDa de truite (Tr65). A partir d'une banque d'ADNc de la peau et des séquences primaires de fragments protéiques obtenus après digestions, le gène de Tr65 a pu être identifié. Le fort caractère hydrophobe de Tr65 et sa puissante activité antibactérienne ont rendu impossible sa production dans différents systèmes in vivo ou in vitro. En suivant les prédictions de structure secondaire et surtout la position des hélices transmembranaires, Tr65 a été découpée en trois fragments qui ont été produits et purifiés avec succès. Seuls les fragments possédant les hélices transmembranaires ont pu restaurer l'activité "formeur" de pores. Par contre, l'activité antibactérienne n'a pu être retrouvée. Ce résultat peut s'expliquer par, (i) leur forte insolubilité dans les milieux permettant la croissance bactérienne, (ii) des problèmes de conformation comme le suggèrent des expériences de dichroïsme circulaire.Many compounds are present in skin mucus of fishes were they serve as the first line of defence against bacterial invasion. Recently, several antibacterial proteins have been extracted from mucus of eel, tench and trout. These proteins have strong antimicrobial activity correlated to a pore forming properties inducing permeabilisation of bacterial membranes. In the first part of this work, we have identified a 55 kDa hydrophobic protein with such activities in the mucus of a sea fish, the turbot. In a second part, we have studied the 65 kDa protein of trout (Tr65). Tr65 gene was identified from skin cDNA library and from primary sequences of digested protein fragments. Due to its strong hydrophobic nature and antibacterial activity, Tr65 could not be successfully produced in in vivo and in vitro systems. According to secondary structure predictions, Tr65 was successfully produced as three protein fragments: N-terminal and C-terminal fragments containing transmembrane helices and a middle one. The segments with transmembrane helices were the only ones to show pore-forming activity in planar lipid bilayers. In contrast no antibacterial activity was observed with any segments. This last result can be explained by: (i) the high insolubility of the segments in bacterial culture media, (ii) the unfolding of the segments as revealed by circular dichroism measurements.ROUEN-BU Sciences (764512102) / SudocSudocFranceF
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