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Search Results: 1 - 10 of 335086 matches for " Bérénice Framery "
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Plant Insecticide L-Canavanine Repels Drosophila via the Insect Orphan GPCR DmX
Christian Mitri,Laurent Soustelle,Bérénice Framery,Jo?l Bockaert,Marie-Laure Parmentier,Yves Grau
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.1000147
Abstract: For all animals, the taste sense is crucial to detect and avoid ingesting toxic molecules. Many toxins are synthesized by plants as a defense mechanism against insect predation. One example of such a natural toxic molecule is l-canavanine, a nonprotein amino acid found in the seeds of many legumes. Whether and how insects are informed that some plants contain l-canavanine remains to be elucidated. In insects, the taste sense relies on gustatory receptors forming the gustatory receptor (Gr) family. Gr proteins display highly divergent sequences, suggesting that they could cover the entire range of tastants. However, one cannot exclude the possibility of evolutionarily independent taste receptors. Here, we show that l-canavanine is not only toxic, but is also a repellent for Drosophila. Using a pharmacogenetic approach, we find that flies sense food containing this poison by the DmX receptor. DmXR is an insect orphan G-protein–coupled receptor that has partially diverged in its ligand binding pocket from the metabotropic glutamate receptor family. Blockade of DmXR function with an antagonist lowers the repulsive effect of l-canavanine. In addition, disruption of the DmXR encoding gene, called mangetout (mtt), suppresses the l-canavanine repellent effect. To avoid the ingestion of l-canavanine, DmXR expression is required in bitter-sensitive gustatory receptor neurons, where it triggers the premature retraction of the proboscis, thus leading to the end of food searching. These findings show that the DmX receptor, which does not belong to the Gr family, fulfills a gustatory function necessary to avoid eating a natural toxin.
Muscle Dystroglycan Organizes the Postsynapse and Regulates Presynaptic Neurotransmitter Release at the Drosophila Neuromuscular Junction
Laurent Bogdanik, Bérénice Framery, Andreas Fr?lich, Bénédicte Franco, Dominique Mornet, Jo?l Bockaert, Stephan J. Sigrist, Yves Grau, Marie-Laure Parmentier
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002084
Abstract: Background The Dystrophin-glycoprotein complex (DGC) comprises dystrophin, dystroglycan, sarcoglycan, dystrobrevin and syntrophin subunits. In muscle fibers, it is thought to provide an essential mechanical link between the intracellular cytoskeleton and the extracellular matrix and to protect the sarcolemma during muscle contraction. Mutations affecting the DGC cause muscular dystrophies. Most members of the DGC are also concentrated at the neuromuscular junction (NMJ), where their deficiency is often associated with NMJ structural defects. Hence, synaptic dysfunction may also intervene in the pathology of dystrophic muscles. Dystroglycan is a central component of the DGC because it establishes a link between the extracellular matrix and Dystrophin. In this study, we focused on the synaptic role of Dystroglycan (Dg) in Drosophila. Methodology/Principal Findings We show that Dg was concentrated postsynaptically at the glutamatergic NMJ, where, like in vertebrates, it controls the concentration of synaptic Laminin and Dystrophin homologues. We also found that synaptic Dg controlled the amount of postsynaptic 4.1 protein Coracle and alpha-Spectrin, as well as the relative subunit composition of glutamate receptors. In addition, both Dystrophin and Coracle were required for normal Dg concentration at the synapse. In electrophysiological recordings, loss of postsynaptic Dg did not affect postsynaptic response, but, surprisingly, led to a decrease in glutamate release from the presynaptic site. Conclusion/Significance Altogether, our study illustrates a conservation of DGC composition and interactions between Drosophila and vertebrates at the synapse, highlights new proteins associated with this complex and suggests an unsuspected trans-synaptic function of Dg.
Plant Insecticide L-Canavanine Repels Drosophila via the Insect Orphan GPCR DmX
Christian Mitri equal contributor,Laurent Soustelle equal contributor,Bérénice Framery,Jo?l Bockaert,Marie-Laure Parmentier,Yves Grau
PLOS Biology , 2009, DOI: 10.1371/journal.pbio.1000147
Abstract: For all animals, the taste sense is crucial to detect and avoid ingesting toxic molecules. Many toxins are synthesized by plants as a defense mechanism against insect predation. One example of such a natural toxic molecule is l-canavanine, a nonprotein amino acid found in the seeds of many legumes. Whether and how insects are informed that some plants contain l-canavanine remains to be elucidated. In insects, the taste sense relies on gustatory receptors forming the gustatory receptor (Gr) family. Gr proteins display highly divergent sequences, suggesting that they could cover the entire range of tastants. However, one cannot exclude the possibility of evolutionarily independent taste receptors. Here, we show that l-canavanine is not only toxic, but is also a repellent for Drosophila. Using a pharmacogenetic approach, we find that flies sense food containing this poison by the DmX receptor. DmXR is an insect orphan G-protein–coupled receptor that has partially diverged in its ligand binding pocket from the metabotropic glutamate receptor family. Blockade of DmXR function with an antagonist lowers the repulsive effect of l-canavanine. In addition, disruption of the DmXR encoding gene, called mangetout (mtt), suppresses the l-canavanine repellent effect. To avoid the ingestion of l-canavanine, DmXR expression is required in bitter-sensitive gustatory receptor neurons, where it triggers the premature retraction of the proboscis, thus leading to the end of food searching. These findings show that the DmX receptor, which does not belong to the Gr family, fulfills a gustatory function necessary to avoid eating a natural toxin.
Auto-biblio-graphies : voir et lire le lecteur. Typologie exploratoire de bibliothèques con ues comme des autoportraits de grands lecteurs
Bérénice Waty
Conserveries Mémorielles : Revue Transdisciplinaire de Jeunes Chercheurs , 2008,
Abstract: Présentant des résultats d’un doctorat sur l’identité des individus lisant 25 livres et plus par an, cet article porte sur les conditions matérielles et symboliques de se vivre grands lecteurs. La bibliothèque, ou plut t les hiérarchies et variations des lieux de rangements du livre sont ainsi observées et questionnées dans l’idée qu’elles forment un portrait de lecteur, reflétant leurs go ts littéraires, certes, mais aussi et surtout leur identité polymorphe de celui qui lit et qui aborde sa vie dans et pour cette passion exclusive. Des murs de livres aux pierres tombales, en passant par des Panthéons littéraires cachés au plus près de soi, ou encore la question des legs d’ouvrages, on constatera que ce public n’a de cesse de multiplier les relations physiques avec l’objet livre et de magnifier ce dernier à chaque moment de leur relation avec lui : après l’achat, avant et après la lecture.L’approche historique sera convoquée pour démontrer en quoi ces discours et actes des grands lecteurs véhiculent un idéal type du lecteur, lettré même, qui se doit d’être uniquement tendu vers le lire. L’architecture et le religieux complèteront cette approche, à travers des exemples de registres lexicaux employés par les grands lecteurs pour parler d’eux.
Claude Simon : une contestation du texte par l’image
Bérénice Bonhomme
Cahiers de Narratologie , 2009, DOI: 10.4000/narratologie.1025
Abstract: L’image joue un r le central dans l’ uvre de Claude Simon. Le r le de l’image plastique appara t d’abord comme un stimulus, mais c’est une image absentée, en creux, mise hors jeux. Inversement, le mot lui-même devient image, tension rentrée vers le visible qui va jusqu’au rébus et au mythogramme, objet biface d’image-parole. L’image comme en creux de l’ uvre a un r le proprement contestataire, faisant bouger les lignes et les frontières, transformant en profondeur non seulement le texte simonien mais aussi notre regard sur lui. The image plays a central role in the work of Claude Simon. The image appears as a stimulus at first, but it is an eclipsed image. It remains only as a footprint which is not in play. Conversely, word itself becomes an image, its tension is turned towards the visible which takes it as far as rebus and mythogramme: the biface object of an image-word. As if in the hollow of the work, the image has a genuinely questioning role, making lines and borders move, transforming in depth not only the simonien text but also ourimpression of it.
Hypertree posets and hooked partitions
Bérénice Oger
Mathematics , 2014,
Abstract: We adapt here the computation of characters on incidence Hopf algebras introduced by W. Schmitt in the 1990s to a family mixing bounded and unbounded posets. We then apply our results to the family of hypertree posets and partition posets. As a consequence, we obtain some enumerative formulas and a new proof for the computation of the Moebius numbers of the hypertree posets. Moreover, we compute the coproduct of the incidence Hopf algebra and recover a known formula for the number of hypertrees with fixed valency set and edge sizes set.
Action of the symmetric groups on the homology of the hypertree posets
Bérénice Oger
Mathematics , 2012,
Abstract: The set of hypertrees on $n$ vertices can be endowed with a poset structure. J. McCammond and J. Meier computed the dimension of the unique non zero homology group of the hypertree poset. We give another proof of their result and use the theory of species to determine the action of the symmetric group on this homology group, which is linked with the anti-cyclic structure of the $\operatorname{Prelie}$ operad. We also compute the action on the Whitney homology of the poset. ----- L'ensemble des hyperarbres \`a $n$ sommets peut \^etre muni d'un ordre partiel. J. McCammond et J. Meier ont calcul\'e la dimension de l'unique groupe d'homologie non trivial du poset des hyperarbres. Apr\`es avoir donn\'e une autre preuve de ce r\'esultat, nous utilisons la th\'eorie des esp\`eces pour d\'eterminer l'action du groupe sym\'etrique sur ce groupe, que nous relions \`a la structure anti-cyclique de l'op\'erade $\operatorname{Prelie}$. Nous calculons aussi l'action du groupe sym\'etrique sur l'homologie de Whitney du poset.
Decorated hypertrees
Bérénice Oger
Computer Science , 2012,
Abstract: C. Jensen, J. McCammond and J. Meier have used weighted hypertrees to compute the Euler characteristic of a subgroup of the automorphism group of a free product. Weighted hypertrees also appear in the study of the homology of the hypertree poset. We link them to decorated hypertrees after a general study on decorated hypertrees, which we enumerate using box trees.---C. Jensen, J. McCammond et J. Meier ont utilis\'e des hyperarbres pond\'er\'es pour calculer la caract\'eristique d'Euler d'un sous-groupe du groupe des automorphismes d'un produit libre. Un autre type d'hyperarbres pond\'er\'es appara\^it aussi dans l'\'etude de l'homologie du poset des hyperarbres. Nous \'etudions les hyperarbres d\'ecor\'es puis les comptons \`a l'aide de la notion d'arbre en bo\^ite avant de les relier aux hyperarbres pond\'er\'es.
Semi-pointed partition posets and Species
Bérénice Delcroix-Oger
Mathematics , 2015,
Abstract: We define semi-pointed partition posets, which are a generalisation of partition posets and show that they are Cohen-Macaulay. We then use multichains to compute the dimension and the character for the action of the symmetric groups on their homology. We finally study the associated incidence Hopf algebra, which is similar to the Fa{\`a} di Bruno Hopf algebra.
Modelling and estimation of genotype by environment interactions for production traits in French dairy cattle
Bérénice Huquet, Hélène Leclerc, Vincent Ducrocq
Genetics Selection Evolution , 2012, DOI: 10.1186/1297-9686-44-35
Abstract: Genetic parameters of production traits were estimated for three breeds (Holstein, Normande and Montbéliarde) using multiple-trait and reaction norm models. Variables derived from Herd Test Day profiles obtained after a test day model evaluation were used to define herd environment.Multiple-trait and reaction norm models gave similar results. Genetic correlations were very close to unity for all traits, except between some extreme environments. However, a relatively wide range of heritabilities by trait and breed was found across environments. This was more the case for milk, protein and fat yields than for protein and fat contents.No real reranking of animals was observed across environments. However, a significant scale effect exists: the more intensive the herd management for milk yield, the larger the heritability.Two main opportunities are available to improve production traits in dairy cattle: through the modification of herd management and/or the genetic level. Except when it is necessary to choose a local breed for a specific environment (such as the Abondance breed in the French Alps), these two opportunities are generally considered separately, as in genetic evaluation. Indeed, they imply the absence of genotype by environment (G*E) interactions, i.e., the breeding value of an animal is assumed to be the same regardless of the environment in which it will be raised. Dealing with this situation, some breeders question the efficiency of current breeding schemes for their own particular management system. Thus, the objective of this study was then to estimate G*E interactions for production traits (milk, protein, fat yields and fat and protein contents) in French dairy cattle. The overall objective was to assess whether these interactions could be an opportunity to better adapt animals to their environment. G*E interaction studies raise three main questions: How to define the genotype? How to describe the environment? Which model to choose in order to estimat
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