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NO presente des activites pro- et anti-apoptotiques. Les parametres gouvernant ces effets commencent a etre elucides. Parmi les facteurs orientant l'action de NO figurent le type et l'etat redox des cellules, la concentration et le flux de NO, la possibilite de reagir avec le superoxyde genere au niveau des mitochondries. Les cibles de NO incluent des molecules impliquees dans la reparation des dommages...
Nous avons utilise une double strategie<space>: celle des souris mutees depourvues d'un type de recepteurs de neurotransmetteur obtenues par recombinaison homologue (souris homozygotes 'knockout' KO 5-HT 1B -/-), et celle pharmacologique utilisant un antagoniste de ces recepteurs pour evaluer la contribution des recepteurs 5-HT 1B de la serotonine (5-hydroxytryptamine,...
The previous fossil record of limbed vertebrates of the Iberian peninsula started in the Triassic (245<space>Ma). The discovery of a new temnospondyl from the Late Carboniferous (Stephanian C, 290<space>Ma) extends the fossil record of stegocephalians in this region by at least 45<space>Ma. Early stegocephalians are usually thought to have been unable to live in salt water, but the...
The distribution of the 36 palm species of New Caledonia is studied in relation to several parameters: elevation, rainfall, geological substrate, phytogeographical sectors and vegetation types. The climate (thermal gradient and rainfall) appears to be the principal factor influencing the distribution of palms, the substrate effect being subordinate to the climatic pattern. Nearly all palm populations...
Quatorze types de structures physiques produites par des ingenieurs ecologiques ont ete echantillonnees a la surface du sol d'une savane colombienne. Les invertebres impliques dans leur production ont ete identifies. Une selection de proprietes physiques (taille et stabilite des agregats, densite apparente) et chimiques (teneur en C, N, P, etc) de ces structures ont ete evaluees. Trois groupes de...
Insect intracellular symbiotic bacteria (intracellular endosymbionts, or endocytobionts) were positioned within the γ3-Proteobacteria using a non-homogeneous model of DNA evolution, allowing for rate variability among sites, for GC content heterogeneity among sequences, and applied to a maximum likelihood framework. Most of them were found to be closely related within the Enterobacteriaceae family,...
Vertition in mites is defined as a meristic variation for a bilateral integumental organ with a separate genetic control for each body side. A prominent hypothesis expressed by Grandjean is the role of vertition in the evolutionary trend towards a reduced number of hair-like organs (mechano- and/or chemo-receptors) known to have occurred in many mite groups. Observations on leg setae in the two-spotted...
Il n y a pas de raison, a priori, qu il existe un lien entre le processus de formation d un organe chez l embryon, et son fonctionnement normal chez l adulte. En general, les organes ne remplissent pas, pendant leur formation, la fonction a laquelle ils sont finalement destines. Cependant, des resultats recents en physique de la croissance hors d equilibre permettent d avancer l existence...
L etude ultrastructurale de Weddellomyces epicallopisma (paroi ascomale, asques, ascospores et hyphes vegetatives), la premiere concernant la famille des Dacampiaceae, confirme la grande majorite des observations faites en microscopie photonique. Elle montre cependant que les ascospores sont pourvues d une endospore (non visible en microscopie photonique) et que la structure de la cloison des ascospores...
L'analyse des isotopes 13 C et 15 N de 47 ossements provenant de la necropole Saint-Laurent-de-Grenoble (Grenoble, Isere), dates du bas Moyen Age (XIII e -XV e siecles), a permis de definir le statut alimentaire des animaux par rapport aux Hommes et de discuter de la variabilite inter-individuelle au sein du groupe des humains. Les individus adultes decedes...
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