C-alpha-Methyl, C-alpha-n-Propylglycine Homo-oligomers

A series of N\u3b1-protected, monodispersed homo-oligopeptide esters to the octamer level from l-C\u3b1-methyl, C\u3b1-n-propylglycine [or C\u3b1-methylnorvaline, (\u3b1Me)Nva] has been synthesized by solution methods and fully characterized. The preferred conformation of these homo-oligomers in solution has been assessed by FT-IR absorption and 1H NMR techniques. Moreover, the molecular structures of the homotrimer and homotetramer have been determined in the crystal state by X-ray diffraction. The obtained results strongly support the view that right-handed, single or multiple, and consecutive \u3b2 bends are preferentially adopted by the conformationally restricted l-(\u3b1Me)Nva homo-oligomers. In particular, 310 helices are formed by the longest homo-oligomers. It is our contention that the [(\u3b1Me)Nva]n peptides represent the best available choice among C\u3b1-tetrasubstituted \u3b1-amino acid-based homo-oligomers for the construction of relatively easy to make, rigid foldamers with a well-defined screw-sense bias

Combined analysis of Perca fluviatilis reproductive performance and oocyte proteomic profile

International audienceThe success of reproduction depends greatly upon gamete quality, especially oocytes which carry most of the molecular material necessary for early embryogenesis. However, it remains difficult to find relevant morphologic and/or biochemical parameters to assess oocyte quality and thus have a reliable prediction of the reproduction performance. To understand which criteria are the most reliable to assess the reproductive success of the Eurasian perch (Perca fluviatilis), we measured 14 parameters characterizing female, spawn, oocyte, and embryonic or larval development on 20 independent spawn. A data analysis allowed the definition of two clusters of spawn with different larval characteristics: the first cluster was composed of spawn which led mainly to strong large larvae presenting a low deformity rate, while the second cluster rather corresponds to spawn leading to smaller and weaker larvae with a higher deformity rate. Moreover, a third cluster (unfertilized spawn) was studied. Our analysis revealed that most of the prefertilization biological traits that we studied appeared poorly relevant to predict larval features, proper embryonic development and deformity occurrences. We thus performed a large scale proteomic analysis to highlight proteins differently expressed in each spawn cluster. A 2D-DIGE study followed by an MS/MS spectrometry allowed the identification of 32 proteins involved in several biological functions and differently expressed between spawn clusters. Among them, proteins involved in cell response to the oxidative stress, as well as energetic metabolism, heat shock proteins and Vitellogenins are of particular interest. Several functions appear specific to a spawn cluster and could thus explain their corresponding reproduction performance. In the future, proteins involved in those cellular mechanisms may constitute molecular markers predictive of the reproduction performance in Perca fluviatilis. (c) 2012 Elsevier Inc. All rights reserved

Utilisation du plutonium de qualité militaire venant du démantèlement des armes russes pour les besoins civils de la production d'électricité

Le 2 juin 1998, la Fédération de Russie, la République Française et la République Fédérale d'Allemagne ont signé un accord trilatéral de coopération (programme AIDA/MOX 2) dans le domaine de l'utilisation pacifique du plutonium issu du démantèlement des armes nucléaires russes soumises à réduction. L'utilisation de ce plutonium sous forme de combustible mixte uranium-plutonium (MOX) destiné à des réacteurs de puissance russes constitue la voie privilégiée de cette coopération. Le Rapport Technique Final du programme AIDA/MOX 2 décrit les résultats des études techniques et économiques des travaux engagés de 1998 à 2002 (publication du Rapport à la mi-2003). Cet article synthétise les résultats obtenus