PEO: An immobile solvent?

Despite used for half a century as host for salt-polymer complexes, PEO is still not a fossil and due to its availability, remains regularly used as a reference in solvent-free polymer electrolytes and related electrochemical cells. Often qualified as macromolecular solvent or immobile solvent, its drawbacks (crystallinity, mechanical strength) are well identified. On the other hand, its electrolyte conductivity maxima are considered as the best possible in absence of molecular solvents or ionic liquids. The comparison of PEO/LiTFSI based on raw PEO and ultrafiltrated one, shows unambiguously the impact of unentangled oligomers not only on ionic transport but also on mechanical behavior. Conductivity, cationic transference numbers and storage modulus data go in the same direction and the cationic conductivity (O/Li = 30) is divided by 2, following PEO purification.Jean-Yves Sanchez acknowledges the CONEX Programme, funding received from Universidad Carlos III de Madrid, the European Union's Seventh Framework Programme for research, technological development and demonstration (Grant agreement nº 600371), Spanish Ministry of Economy and Competitiveness (COFUND2013-40258) and Banco Santander. Amadou Thiam acknowledges ANR for his fellowship. Yannick Molméret acknowledges KICINNO Energy for the granting of his post-doc fellowship, in the frame of the project PENLiB coordinated by Prof. Jean-Yves Sanchez

Proteomic Analysis of Growth Phase-Dependent Expression of Legionella pneumophila Proteins Which Involves Regulation of Bacterial Virulence Traits

Legionella pneumophila, which is a causative pathogen of Legionnaires' disease, expresses its virulent traits in response to growth conditions. In particular, it is known to become virulent at a post-exponential phase in vitro culture. In this study, we performed a proteomic analysis of differences in expression between the exponential phase and post-exponential phase to identify candidates associated with L. pneumophila virulence using 2-Dimentional Fluorescence Difference Gel Electrophoresis (2D-DIGE) combined with Matrix-Assisted Laser Desorption/Ionization–Mass Spectrometry (MALDI-TOF-MS). Of 68 identified proteins that significantly differed in expression between the two growth phases, 64 were up-regulated at a post-exponential phase. The up-regulated proteins included enzymes related to glycolysis, ketone body biogenesis and poly-3-hydroxybutyrate (PHB) biogenesis, suggesting that L. pneumophila may utilize sugars and lipids as energy sources, when amino acids become scarce. Proteins related to motility (flagella components and twitching motility-associated proteins) were also up-regulated, predicting that they enhance infectivity of the bacteria in host cells under certain conditions. Furthermore, 9 up-regulated proteins of unknown function were found. Two of them were identified as novel bacterial factors associated with hemolysis of sheep red blood cells (SRBCs). Another 2 were found to be translocated into macrophages via the Icm/Dot type IV secretion apparatus as effector candidates in a reporter assay with Bordetella pertussis adenylate cyclase. The study will be helpful for virulent analysis of L. pneumophila from the viewpoint of physiological or metabolic modulation dependent on growth phase

Molecular Mimicry by an F-Box Effector of Legionella pneumophila Hijacks a Conserved Polyubiquitination Machinery within Macrophages and Protozoa

The ability of Legionella pneumophila to proliferate within various protozoa in the aquatic environment and in macrophages indicates a remarkable evolution and microbial exploitation of evolutionarily conserved eukaryotic processes. Ankyrin B (AnkB) of L. pneumophila is a non-canonical F-box-containing protein, and is the only known Dot/Icm-translocated effector of L. pneumophila essential for intra-vacuolar proliferation within both macrophages and protozoan hosts. We show that the F-box domain of AnkB and the 9L10P conserved residues are essential for intracellular bacterial proliferation and for rapid acquisition of polyubiquitinated proteins by the Legionella-containing vacuole (LCV) within macrophages, Dictyostelium discoideum, and Acanthamoeba. Interestingly, translocation of AnkB and recruitment of polyubiquitinated proteins in macrophages and Acanthamoeba is rapidly triggered by extracellular bacteria within 5 min of bacterial attachment. Ectopically expressed AnkB within mammalian cells is localized to the periphery of the cell where it co-localizes with host SKP1 and recruits polyubiquitinated proteins, which results in restoration of intracellular growth to the ankB mutant similar to the parental strain. While an ectopically expressed AnkB-9L10P/AA variant is localized to the cell periphery, it does not recruit polyubiquitinated proteins and fails to trans-rescue the ankB mutant intracellular growth defect. Direct in vivo interaction of AnkB but not the AnkB-9L10P/AA variant with the host SKP1 is demonstrated. Importantly, RNAi-mediated silencing of expression of SKP1 renders the cells non-permissive for intracellular proliferation of L. pneumophila. The role of AnkB in exploitation of the polyubiquitination machinery is essential for intrapulmonary bacterial proliferation in the mouse model of Legionnaires' disease. Therefore, AnkB exhibits a novel molecular and functional mimicry of eukaryotic F-box proteins that exploits conserved polyubiquitination machinery for intracellular proliferation within evolutionarily distant hosts

Real-time analysis of polymer flow under real processing conditions applied to microinjection molding

International audienc

PEO: An immobile solvent?

International audienc