Γ-convergence for a class of action functionals induced by gradients of convex functions

Given a real function f , the rate function for the large deviations of the di usion process of drift 'f given by the Freidlin-Wentzell theorem coincides with the time integral of the energy dissipation for the gradient flow associated with f . This paper is concerned with the stability in the hilbertian framework of this common action functional when f varies. More precisely, we show that if (fh)h is uniformly λ-convex for some λ ∈ R and converges towards f in the sense of Mosco convergence, then the related functionals G-converge in the strong topology of curves

Modifications structurales et fonctionnelles de communautés d'organismes aquatiques exposées à un mélange d'herbicide et d'adjuvant en mésocosmes lentiques.

Modifications structurales et fonctionnelles de communautés d'organismes aquatiques exposées à un mélange d'herbicide et d'adjuvant en mésocosmes lentiques.. Colloque de restitution du Programme "Evaluation et réduction des risques liés à l'utilisation des pesticides" du MED

Geographical variation of gene diversity of Pinus pinaster Ait. in the Iberian Peninsula

International audienceThe geographical variation of 25 native populations of maritime pine (Pinus pinaster Ait.) was studied using ten allozymes encoded by 16 loci. A phylogenetic tree based on Nei’s unbiased genetic distance and a Mantel’s randomization test were made. Geostatistical analysis was used for describing in more detail spatial patterns of gene frequencies. The phylogenetic analysis found a clear clustering in northwestern populations and a complex pattern, with two differentiated groups, in the southeastern and eastern regions. Clinal trends of variation and fine-scale spatial structure were detected by geostatistical analysis. Directional clinal variation was found from south to north and, though to a lesser extend, from east to west. This pattern was stronger when populations were separated by more than 250 km. The long-distance founder events during postglacial spread and the orientation of the main mountain ranges are proposed to be the main causes of the geographical structure of this species

Purification of plasma membranes from leaves of conifer and deciduous tree species by phase partitioning and free-flow electrophoresis

Purified plasma membrane fractions were obtained from leaves of Picea abies L., Pinus sylvestris L., Fagus sylvatica L. and Quercus robur L., whereas plasma membranes from Pinus halepensis Mill, proved to be more difficult to obtain, perhaps due to the higher content of volatile substances in this plant species. Plasma membranes were purified by both phase partitioning and free-flow electrophoresis from microsomal fractions and identified on the basis of biochemical and in some cases morphological and cytochemical markers. Electron micrographs revealed that membrane vesicles from Pinus sylvestris exhibited a very clear dark-light-dark pattern and measurements of membrane thickness showed that it ranged from 6 to 10 nm. Most membranes were 8 nm thick and stained with phosphotungstic acid at low pH, both typical characteristics of the plasma membrane. Enzymatic identification of plasma membranes consisted in the determination of the vanadate-sensitive ATPase (EC 3.6.1.3) activity. The specific activity in the upper phase (U2) fraction was 10–25 times higher than those in the lower phase and microsomal fractions, depending on plant species. 1,3-β-glucan synthase II (EC 2.4.1.3), another putative plasma membrane marker, was not detected in the plasma membrane-enriched fractions of conifer needles and showed a very low specific activity in membranes of deciduous trees. Contamination by membranes of other origin was determined by analysis of membrane markers: cytochrome c oxidase (EC 1.9.3.1) for mitochondria, inosine diphosphatase (EC 3.6.1.6) for Golgi apparatus, cytochrome c reductase (EC 1.6.2.4) for endoplasmic reticulum, and pyrophosphatase (EC 3.6.1.1) for tonoplasts. The main, but relatively low contamination, was due to tonoplasts, as determined by the activity of pyrophosphatase. Plasma membrane characteristics were quite different depending on the season during which needles were taken. Membrane preparations of better quality were more easily obtained from samples taken during winter