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Search Results: 1 - 10 of 3674 matches for " Yves Grau "
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Dynamics of glutamatergic signaling in the mushroom body of young adult Drosophila
Irina Sinakevitch, Yves Grau, Nicholas J Strausfeld, Serge Birman
Neural Development , 2010, DOI: 10.1186/1749-8104-5-10
Abstract: To address the role of Glu signaling in the development and maturation of the MB, we have compared the time course of Glu immunoreactivity with the expression of various glutamatergic markers at various times, that is, 1 hour, 1 day and 10 days after adult eclosion. We observed that last-born α/βc KCs in young adult as well as developing KCs in late larva and at various pupal stages transiently express high level of Glu immunoreactivity in Drosophila. One day after eclosion, the Glu level was already markedly reduced in the α/βc neurons. Glial cell processes expressing glutamine synthetase and the Glu transporter dEAAT1 were found to surround the Glu-expressing KCs in very young adults, subsequently enwrapping the α/β lobes to become distributed equally over the entire MB neuropil. The vesicular Glu transporter DVGluT was detected by immunostaining in processes that project within the MB lobes and pedunculus, but this transporter is apparently never expressed by the KCs themselves. The NMDA receptor subunit dNR1 is widely expressed in the MB neuropil just after eclosion, but was not detected in the α/βc neurons. In contrast, we provide evidence that DmGluRA, the only Drosophila mGluR, is specifically expressed in Glu-accumulating cells of the MB α/βc immediately and for a short time after eclosion.The distribution and dynamics of glutamatergic markers indicate that newborn KCs transiently accumulate Glu at a high level in late pupal and young eclosed Drosophila, and may locally release this amino acid by a mechanism that would not involve DVGluT. At this stage, Glu can bind to intrinsic mGluRs abundant in the α/βc KCs, and to NMDA receptors in the rest of the MB neuropil, before being captured and metabolized in surrounding glial cells. This suggests that Glu acts as an autocrine or paracrine agent that contributes to the structural and functional maturation of the MB during the first hours of Drosophila adult life.The neurotransmitter L-glutamate (Glu) plays essent
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.
H2 and CH4 Sorption on Cu-BTC Metal Organic Frameworks at Pressures up to 15 MPa and Temperatures between 273 and 318 K  [PDF]
Yves Gensterblum
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2011, DOI: 10.4236/jsemat.2011.12004
Abstract: Sorption isotherms of methane and hydrogen on Cu3(BTC)2 have been measured in the temperature range from 273 to 318 K and at pressures up to 15 MPa. H2 excess sorption capacities of the Cu3(BTC)2 amounted to 3.9 mg/g at 14 MPa. Promising maximum CH4 excess sorption capacities on the same sample were reached at approximately 5 MPa. They amounted to 101, 100, 92 and 80 mg/g at 273, 278, 293 and 318 K, respectively. The sorbed phase density was essestially the same for all temperatures and amounted to ~600 kg/m3. Structural changes of the Cu3(BTC)2 samples after thermal activation and treatment with high pressure H2 and CH4 were tested. It was found that the initial micropore structure has virtually disappeared as evidenced by a decrease of the Langmuir specific surface area by a factor ~3 and CO2 micropore volume by a factor of ~4 for H2 and ~3 for CH4. This is in line with an increase in the average pore diameter from initially 9.2 to 15.7 for H2 and 12.8 for CH4.
Minkowskian Solution of General Relativity with Cosmological Constant and the Accelerating Universe  [PDF]
Yves Pierseaux
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.516172
Abstract: A Minkowskian solution of the equation of General Relativity (as written by Einstein in 1915) is trivial because it simply means that both members of the equation are equal to zero. However, if alternatively, one considers the complete equation with a non-zero constant Λ (Einstein 1917), a Minkowskian solution is no longer trivial because it amounts to impose a constraint on the right hand side of the equation (i.e. a non-null stress-energy tensor). If furthermore one identifies (as usual) this tensor to the one of a perfect fluid, one finds that this fluid has a positive energy density and a negative pressure that depend on the three constants of the equation (i.e. gravitational constant G, cosmological constant Λ and velocity of light c). When doing that (§1), one has to consider the “Minkowskian Vacuum” as a physical object of GR (an enigmatic non-baryonic Minkowskian fluid). Can one build a model of this object on the basis of a dynamical equilibrium between the effective gravitational attraction due to the positive energy density versus the negative pressure repulsion? We propose to study such a model, where the (enigmatic) fluid is assumed to exist only in a limited sphere whose surface acts like a “test body” sensitive to the gravitational field created by the fluid. No static equilibrium exists, but a pseudoNewtonian “dynamical equilibrium” (§2) can be reached if the pseudoEuclidean fluid is in state of expansion. Up to there, we have simply constructed a model of an “abstract Universe” (i.e. the limited sphere: There is no fluid outside this sphere!) that gives to a (purely mathematical) constant Λ a concrete physical meaning. We discover finally that our expanding fluid has not only dynamical (gravitational) properties (§3) but also optical properties that are connected with Doppler Redshift (§4). Remembering that recent observations in Cosmology indicate that the “real Universe” seems to be “Flat” and in “Accelerated Expansion”; remembering also (after all) that the archetypal Flat Universe is simply a Minkowskian Universe, we logically wonder if the unexpected Minkowskian global solution, could not be also a significant cosmological model (conclusion).
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.
Gαo Is Required for L-Canavanine Detection in Drosophila
Isabelle Devambez, Moutaz Ali Agha, Christian Mitri, Jo?l Bockaert, Marie-Laure Parmentier, Frédéric Marion-Poll, Yves Grau, Laurent Soustelle
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0063484
Abstract: Taste is an essential sense for the survival of most organisms. In insects, taste is particularly important as it allows to detect and avoid ingesting many plant toxins, such as L-canavanine. We previously showed that L-canavanine is toxic for Drosophila melanogaster and that flies are able to detect this toxin in the food. L-canavanine is a ligand of DmXR, a variant G-protein coupled receptor (GPCR) belonging to the metabotropic glutamate receptor subfamily that is expressed in bitter-sensitive taste neurons of Drosophila. To transduce the signal intracellularly, GPCR activate heterotrimeric G proteins constituted of α, β and γ subunits. The aim of this study was to identify which Gα protein was required for L-canavanine detection in Drosophila. By using a pharmacological approach, we first demonstrated that DmXR has the best coupling with Gαo protein subtype. Then, by using genetic, behavioral assays and electrophysiology, we found that Gαo47A is required in bitter-sensitive taste neurons for L-canavanine sensitivity. In conclusion, our study revealed that Gαo47A plays a crucial role in L-canavanine detection.
El Pic del mal del Aire The Pic del mal del Aire
Grau Arantxa
Index de Enfermería , 2004,
Abstract:
SELF-GOVERNMENT REFORMS AND PUBLIC SUPPORT FOR SPAIN'S TERRITORIAL MODEL: CHANGES AND STABILITY (1992-2010)
Mireia Grau
Revista d'Estudis Autonòmics i Federals , 2011,
Abstract: This article explores the changes that have taken place in public opinion preferences with respect to the model of political organisation in Spain following the last wave of statutory reforms. The article is based on data collected from surveys carried out by the Centre for Sociological Research between 2002 and 2010 and aims primarily to detecting the extent to which the preference for a model of decentralisation, such as that which currently exists (and which is referred to as the “status quo” throughout the article) has undergone major changes during the period of analysis, and in which autonomous communities. The article concludes that simultaneous to the statutory reforms there have been major changes in public perception of the “institutional goodwill” that exists in the current institutional model of decentralisation and self-government. Specifically, while some communities under the current model have begun to question why it cannot adapt to some of the more ambitious expectations of self-government, in other communities the present model has been questioned precisely for the opposite reason: to understand why the current model of political decentralisation has gone too far. So for the first time in some of the autonomous communitiesthe preference for self-government involution (i.e., preference for centralism and cuts in self-government powers) is greater than that expressed in the current decentralisation model.
Entsch digungs- und Rückerstattungsakten als neue Quelle der Zeitgeschichtsforschung am Beispiel Bayerns
Grau, Bernhard
Zeitenblicke , 2004,
Abstract: Entsch digungs- und Rückerstattungsakten werden erst seit kurzem zur Erforschung der Wiedergutmachung und der nationalsozialistischen Verfolgungsma nahmen ausgewertet. Ins Blickfeld gerieten zum einen die staatlichen Instanzen, die die Ausplünderung der Verfolgten zu verantworten hatten, und zum anderen die Praxis von Wiedergutmachung und Entsch digung im individuellen Einzelfall. Nach dem Erlass entsprechender Gesetze wurden in den einzelnen Besatzungszonen bzw. Bundesl ndern Entsch digungs- bzw. Rückerstattungsbeh rden gegründet, die die Antr ge der Betroffenen bearbeiteten. Die daraus entstandenen Einzelfallakten dokumentieren den in dieser Form einzigartigen Versuch, individuellen Schadensersatz zu leisten. Allein für Bayern sind rund 235.000 Entsch digungs- und rund 80.000 Rückerstattungsakten vorhanden. Der Gro teil der Entsch digungsakten lagert noch bei der Landesentsch digungsbeh rde, die nach wie vor Betroffene betreut. Die bereits in Archiven befindlichen Akten sind unter Einhaltung bestimmter Sperr- und Personenschutzbestimmungen für die Forschung zug nglich.
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