MAVS ubiquitination by the E3 ligase TRIM25 and degradation by the proteasome is involved in type I interferon production after activation of the antiviral RIG-I-like receptors

<p>Abstract</p> <p>Background</p> <p>During a viral infection, the intracellular RIG-I-like receptors (RLRs) sense viral RNA and signal through the mitochondrial antiviral signaling adaptor MAVS (also known as IPS-1, Cardif and VISA) whose activation triggers a rapid production of type I interferons (IFN) and of pro-inflammatory cytokines through the transcription factors IRF3/IRF7 and NF-κB, respectively. While MAVS is essential for this signaling and known to operate through the scaffold protein NEMO and the protein kinase TBK1 that phosphorylates IRF3, its mechanism of action and regulation remain unclear.</p> <p>Results</p> <p>We report here that RLR activation triggers MAVS ubiquitination on lysine 7 and 10 by the E3 ubiquitin ligase TRIM25 and marks it for proteasomal degradation concomitantly with downstream signaling. Inhibition of this MAVS degradation with a proteasome inhibitor does not affect NF-κB signaling but it hampers IRF3 activation, and NEMO and TBK1, two essential mediators in type I IFN production, are retained at the mitochondria.</p> <p>Conclusions</p> <p>These results suggest that MAVS functions as a recruitment platform that assembles a signaling complex involving NEMO and TBK1, and that the proteasome-mediated MAVS degradation is required to release the signaling complex into the cytosol, allowing IRF3 phosphorylation by TBK1.</p

How to optimize fruit and berry cultivar selection for organic farmers ? A comparison of European approaches.

Most of the currently grown commercial fruit cultivars remain unsuitable to low-input or sustainable organic farming systems. The major reason is that they have been developed and selected under high input cultivation, and without sufficient attention to susceptibility to pests and diseases. Some of these cultivars are nevertheless marketed as resistant because they carry genetic markers for major resistance genes but these are unfortunately prone to break-down (most of apple resistant cultivars relay only on the Vf). As a result, new fruit cultivars tend to reveal unexpected and often undesirable traits when grown in commercial organic orchards, and thus fail to bring about the much needed expansion in organic production and market availability. However, research is ongoing, and some institutions in Europe have established specific approaches in their breeding programs for testing new selections and cultivars under entirely organic conditions – sometimes including also evaluation of storage capability, consumer acceptance or suitable characteristics for juice and cider processing. This paper gives an overview of approaches developed in some European countries, their characteristics, objectives and results. It shows a number of different ways to address a difficult topic. We conclude that it is very desirable to – on a European level – exchange results and ideas to further improve the testing systems, and to increase the distribution of promising cultivars for the European organic fruit sector

Xanthomonas des arbres fruitiers à noyau (Hortipratic)

National audienceLa maladie des taches bactériennes, causée par la bactérie Xanthomonas arboricola pv. pruni, provoque depuis 1999 de graves dégâts dans les vergers de fruits à noyau du sud de la France. Cet ouvrage se veut avant tout un guide pratique à la disposition des arboriculteurs, pépiniéristes et techniciens. Il permet la reconnaissance de la maladie, ainsi que la mise en œuvre des mesures prophylactiques pour retarder son installation et des méthodes de lutte utilisables pour en limiter les effets lorsqu’elle est établie. Les nouvelles avancées scientifiques sur la biologie et l’épidémiologie de la maladie sont également abordées

Snecma's Viewpoint on the Numerical and Experimental Simulation of Blade-Tip/Casing Unilateral Contacts

International audienceAircraft engine manufacturers are developping a new generation of turbojet engines featuring a lower impact on the environment, increased performances as well as reduced gas consumption. The efficiency of an engine is mostly driven by the operating clearance between the rotating parts and the stator. Accordingly, modern designs focus on the minimization of these clearances. In this context, unavoidable rotor imbalances or mistuning stemming from manufacturing processes as well as distortions resulting from thermal expansion or assembly conditions may generate blade-tip/casing contacts that are now considered as non-accidental operating conditions. In order to minimize the consequences of such events, an abradable coating is sprayed along the inner surface of the casing and acts as a fuse when the blade and the casing are in contact. However, even when an abradable coating is used, significant structural damages and wear as well as blade failures have been witnessed experimentally. The understanding of the physical phenomena at play called, on one hand, for throrough experimental investigations of rotor/stator contacts on full-scale stages of compressors and underlined that blade failure is mainly due to vibratory fatigue although the abradable coating is worn. On the other hand, numerical simulations have been performed to better understand the blade dynamics: over the last decade Snecma and its academic partners jointly developed a code for the simulation of COntacts between ROtor and Stator: COROS. This code allows for the simulation of contacts—with a Lagrange multiplier contact treatment procedure—between full 3D models of engine components and accounts for abradable coating material removal. In particular, the simulation of experimental setups with COROS highlighted the correlation between the blade vibratory response and the abradable material removal. Yet still an experimental code, this paper addresses the integration of COROS within the design process of aircraft engine blades at Snecma. The paper focuses on ongoing research for the identification of critical parameters in the arising of interactions as early as the design stage of components. A particular attention is paid to the mechanical properties of the abradable coating for which both experimental and numerical investigations are detailed

Numerical-experimental comparison in the simulation of rotor/stator interaction through blade-tip/abradable coating contact”. Journal of Engineering for Gas Turbines and Power

Higher aircraft energy efficiency may be achieved by minimizing the clearance between the rotating blade tips and respective surrounding casing. A common technical solution consists in the implementation of an abradable liner which improves both the operational safety and the efficiency of modern turbomachines. However, unexpected abradable wear removal mechanisms were recently observed in experimental set-ups as well as during maintenance procedures. Based on a numerical strategy previously developed, the present study introduces a numerical-experimental comparison of such occurrence. Attention is first paid to the review and analysis of existing experimental results. Good agreement with numerical predictions is then illustrated in terms of critical stress levels within the blade as well as final wear profiles of the abradable liner. Numerical results suggest an alteration of the abradable mechanical properties in order to explain the outbreak of a divergent interaction. New blade designs are also explored in this respect and it is found that the interaction phenomenon is highly sensitive to (1) the blade geometry, (2) the abradable material properties and (3) the distortion of the casing

Comportement dynamique d'une aube de compresseur haute-pression sous l'effet cumulé d'un chargement aérodynamique et de contraintes unilatérales de contact

International audienceRecent studies focused on the numerical prediction of structural instabilities that may arise in rotating components of an aircraft engine. These instabilities are commonly classified into two categories: those induced by aerodynamic phenomena (such as the pressure applied on the blade by the incoming air flow) and those related to structural phenomena (such as potential blade/casing contacts). Based on an existing numerical strategy for the analysis of rotor/stator interactions induced by unilateral contacts between rotating and static components, this paper aims at combining both types of instabilities and provides a qualitative analysis of structural interactions that may arise within the high-pressure compressor of an aircraft engine. The aerodynamic pressure on the blade is simplified as a sinusoidal external load whose frequency depends on the number of upstream guide vanes. Results are presented both in time and frequency domains. Detailed bifurcation diagrams and Poincaré maps underline the fundamental differences in the nature of the witnessed interactions with and without aerodynamic loading on the blade.Plusieurs etudes récentes ont eu pour objet la simulation numérique des instabilités structurelles pouvant survenir dans des machines tournantes telles que des moteurs d'avion. Typiquement, ces instabilités sont séparées en deux catégories : celles relatives aux phénom enes aérodynamiques (liés par exemplè a la pression imposée sur l'aube par le flux d'air) et celles relatives a des phénom enes uniquement structurels (comme le contact aube/carter). En se basant sur l'utilisation d'une méthode numérique dédiéè a l'analyse d'interactions aube/carter initiées par des contacts entre parties tournante et fixe, les travaux présentés dans cet article ont pour objectif d'analyser conjointement les deux types d'instabilité précédemment citées et de fournir une analyse qualitative des types de régimes d'interactions pouvant survenir dans un moteur d'avion. La pression aérodynamique est modéliséè a l'aide d'un chargement externe d'amplitude sinuso¨dale et dont la fréquence dépend du nombre de redresseurs en aval. Les résultats sont donnés dans les espace temporel et fréquentiel. Les différences fondamentales de nature entre les différentes interactions simulées avec et sans pression aérodynamique sont mises en evidence par des diagrammes de bifurcation détaillés et des cartes de Poincaré