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344 results on '"Leveque, C"'

103. Interaction of cysteine string proteins with the alpha1A subunit of the P/Q-type calcium channel.

Author

Leveque, C, Pupier, S, Marqueze, B, Geslin, L, Kataoka, M, Takahashi, M, De Waard, M, and Seagar, M

Abstract

Cysteine string proteins (Csps) are J-domain chaperone proteins anchored at the surface of synaptic vesicles. Csps are involved in neurotransmitter release and may modulate presynaptic calcium channel activity, although the molecular mechanisms are unknown. Interactions between Csps, proteins of the synaptic core (SNARE) complex, and P/Q-type calcium channels were therefore explored. Co-immunoprecipitation suggested that Csps occur in complexes containing synaptobrevin (VAMP), but not syntaxin 1, SNAP-25, nor P/Q-type calcium channels labeled with 125I-omega-conotoxin MVIIC. However binding experiments with 35S-labeled Csp1 demonstrated an interaction (apparent KD = 700 nM at pH 7.4 and 4 degreesC) with a fusion protein containing a segment of the cytoplasmic loop linking homologous domains II-III of the alpha1A calcium channel subunit (BI isoform, residues 780-969). Binding was specific as it was displaced by unlabeled Csp1, and no interactions were detected with fusion proteins containing other calcium channel domains, VAMP, or syntaxin 1A. A Csp binding site on the P/Q-type calcium channel is thus located within the 200 residue synaptic protein interaction site that can also bind syntaxin I, SNAP-25, and synaptotagmin I. Csp may act as a molecular chaperone to direct assembly or disassembly of exocytotic complexes at the calcium channel.

Published
1998

104. Interaction of SNARE complexes with P/Q-type calcium channels in rat cerebellar synaptosomes.

Author

Martin-Moutot, N, Charvin, N, Leveque, C, Sato, K, Nishiki, T, Kozaki, S, Takahashi, M, and Seagar, M

Abstract

P- and Q-type calcium channels, which trigger rapid neurotransmitter release at many mammalian synapses, are blocked by omega-conotoxin MVIIC. 125I-omega-Conotoxin MVIIC binding to rat cerebellar synaptosomes was not displaced by omega-conotoxins GVIA or MVIIA (Ki > 1 microM), which are selective for N-type calcium channels. Solubilized 125I-omega-conotoxin MVIIC receptors were specifically recognized by antibodies directed against alpha1A calcium channel subunits, proteins known to constitute a pore with P/Q-like channel properties. Antibodies against syntaxin 1, SNAP 25, and VAMP 2 (synaptobrevin) each immunoprecipitated a similar fraction (20-40%) of omega-conotoxin MVIIC receptors. Immunoprecipitation was not additive, suggesting that heterotrimeric (SNARE) complexes containing these three proteins interact with P/Q-type calcium channels. Immobilized monoclonal anti-syntaxin antibodies retained alpha1A calcium channel subunits of 220, 180 and 160 kDa monitored by immunoblotting with site directed antibodies. Synaptotagmin was detected in channel-associated complexes, but not synaptophysin, Rab 3A nor rat cysteine string protein. Trimeric SNARE complexes are implicated in calcium-dependent exocytosis, a process thought to be regulated by synaptotagmin. Our results indicate that these proteins interact with P/Q-type calcium channels, which may optimize their location within domains of calcium influx.

Published
1996

105. Les espèces exotiques envahissantes, pour une remise en cause des paradigmes écologiques Invasive species: challenging the ecological paradigms

Author

LEVEQUE, Christian, TABACCHI, Eric, MENOZZI, Marie-Jo

Subjects
GESTION, ESPECES, INVASIONS BIOLOGIQUES, EXOTIQUE, ECOLOGIE, Environmental technology. Sanitary engineering, TD1-1066, Environmental sciences, GE1-350
Abstract

Les espèces exotiques font couler beaucoup d'encre et sont souvent présentées de manière négative. On les accuse de devenir envahissantes, d'entrer en concurrence avec les espèces autochtones, d'entraîner un dysfonctionnement des écosystèmes, et d'avoir un coût élevé pour l'économie. Cet article propose de dépasser ces points de vue parfois simplistes et réducteurs, en étudiant l'aspect sémantique et les définitions données à ces espèces, pour ensuite élaborer des pistes de réflexion sur la façon de composer avec elles.As a result of the high human pressure on aquatic and semiaquatic ecosystems, new species introduced from several parts of the World are increasingly observed. Some of these species become invasive and are expected to threaten biodiversity and ecosystem functioning. This paper is an attempt to disentangle scientific facts or theories from conventional wisdom based on subjective perception or cultural pictures. Especially, we point out that in face of a real threat for biodiversity and ecosystem functioning, invasive species may have positive effects or uses. Several issues in invasion management are examined. While characteristics of invasive species cannot easily be predicted, many invasions take place in previously modified ecosystems. Furthermore, invaders eradication is not always the best answer for targeting self-sustainable healthy ecosystems. Since exotic species will irrevocably increase in proportion within our ecological communities in the next future, one may be ready to adapt to this novel biodiversity by accepting or managing the presence of some invaders.

Published
2012

116. Title

Author

Waldmann, V., primary, Leveque, C., additional, Levron, J. C., additional, Guerin, G., additional, and Cousin, M. Th., additional

Published
1989
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119. A multimodal matching application to optimize neurosurgery and brain stereotaxic irradiation: requirements and realization

Author

de Dreuille, O., primary, Foehrenbach, H., additional, Sabbah, P., additional, Pereira, P., additional, Mangin, J.F., additional, Nioche, C., additional, Dutertre, G., additional, Bellegou, N., additional, Leveque, C., additional, Frouin, V., additional, Cordoliani, Y.S., additional, Desgeorges, M., additional, and Gaillard, J.F., additional

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150. Global diversity of dipteran families (Insecta Diptera) in freshwater (excluding Simulidae, Culicidae, Chironomidae, Tipulidae and Tabanidae)

Author

Wagner, Rüdiger, Barták, Miroslav, Borkent, Art, Courtney, Gregory, Goddeeris, Boudewijn, Haenni, Jean-Paul, Knutson, Lloyd, Pont, Adrian, Rotheray, Graham E., Rozkošný, Rudolf, Sinclair, Bradley, Woodley, Norman, Zatwarnicki, Tadeusz, Zwick, Peter, Martens, K., editor, Balian, E. V., editor, Lévêque, C., editor, and Segers, H., editor

Published
2008
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