Front. Plant. Sci.

Plasmodesmata (PD) pores connect neighbouring plant cells and enable direct transport across the cell wall. Understanding the molecular composition of these structures is essential to address their formation and later dynamic regulation. Here we provide a biochemical characterisation of the cell wall co-purified with primary PD of Arabidopsis thaliana cell cultures. To achieve this result we combined subcellular fractionation, polysaccharide analyses and enzymatic fingerprinting approaches. Relative to the rest of the cell wall, specific patterns were observed in the PD fraction. Most xyloglucans, although possibly not abundant as a group, were fucosylated. Homogalacturonans displayed short methylated stretches while rhamnogalacturonan I species were remarkably abundant. Ful l rhamnogalacturonan II forms, highly methyl-acetylated, were also present. We additionally showed that these domains, compared to the broad wall, are less affected by wall modifying activities during a time interval of days. Overall, the protocol and the data presented here open new opportunities for the study of wall polysaccharides associated with PD.Ecole Universitaire de Recherche de Sciences des Plantes de Paris-SaclayThe function of membrane tethering in plant intercellular communicatio

Adaptive responses of animals to climate change are most likely insufficient

Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species

Étude par RMN de la reconnaissance chirale par des cyclodextrines modifiées

Le mono-3A, 6A-anhydro-cyclomaltohcptaose est un analogue de la β-cyclodextrine présentant une réduction totale de symétrie induisant des propriétés de reconnaissance chirale remarquables. Une étude structurale par RMN a été effectuée sur un complexe d’inclusion formé avec un atropo-isomère, la dothiépine. Cette étude a montré que chaque énantiomère forme un complexe d’inclusion de structure et d’affinité différentes

Self assemblies of amphiphilic cyclodextrins

International audienc

Lipid Lateral Segregation driven by Diacyl Cyclodextrin Interactions at the Membrane Surface

International audienc

Substituent effect on redox potential of terephthalate-based electrode materials for lithium batteries

The substituent effect on the redox potential of lithium terephthalate was studied using symmetrical dilithium disubstituted-terephthalates incorporating bromo, methoxy and amino groups. All the terephthalate derivatives have been synthesized and evaluated as anode material for lithium-ion batteries. The electrochemical results revealed an increase in the reduction potential in the case of bromo and methoxy groups and almost the same in the case of amino group compared to unmodified dilithium terephthalate. In addition, a very first tendency between the 13C chemical shifts and FTIR signal of the carbonyl and the reduction potential of the studied disubstituted-terephthalates was formulated. Keywords: Organic anode materials, Substituent effect, Structure-property relationships, Lithium batterie

Identification of Li battery electrolyte degradation products through direct synthesis and characterization of alkyl carbonate salts

Aiming toward the identification of carbonate-based electrolyte degradation species formed during high-temperature cycling of Li/M-O cells, we have embarked in the synthesis and characterization of lithium-based alkyl carbonates. Through the reaction of commercial or synthesized lithium alkoxides with carbon dioxide, we succeeded in preparing lithium methyl, ethyl, propyl mono carbonates, and therefore we have extended our work to the synthesis of lithium ethandiol-bis carbonate. Their analytical characterization ( 1H and 13C nuclear magnetic resonance, electrospray ionization-mass spectroscopy, Fourier transform: infrared/attenuated total reflection) is described. Furthermore, to our surprise, we managed to demonstrate that these well-known alkyl carbonates show some electrochemical reactivity toward Li. © 2005 The Electrochemical Society. All rights reserved