Oligonucleotide nanostructured surfaces: effect on Escherichia coli curli expression

Oligonucleotide model surfaces allowing independent variation of topography and chemical composition were designed to study the adhesion and biofilm growth of E.coli. Surfaces were produced by covalent binding of oligonucleotides and immobilization of nucleotide-based vesicles. Their properties were confirmed through a combination of fluorescence microscopy, XPS, ellipsometry, AFM and wettability studies at each step of the process. These surfaces were then used to study the response of three different strains of E.coli quantified in a static biofilm growth mode. This study led to convincing evidence that oligonucleotide-modified surfaces, independent of the topographical feature used in this study, enhanced curli expression without an increase in the number of adherent bacteria.     

Identification of new<Emphasis Type="Italic"> O</Emphasis>-GlcNAc modified proteins using a click-chemistry-based tagging

The O-linked β-N-acetylglucosamine (O-GlcNAc) modification is an abundant post-translational modification in eukaryotic cells. This dynamic glycosylation plays a fundamental role in the activity of many nuclear and cytoplasmic proteins and is associated with pathologies like type II diabetes, Alzheimer’s disease or some cancers. However the exact link between O-GlcNAc-modified proteins and their function in cells is largely undefined for most cases. Here we report a strategy based on the 1,3-dipolar cycloaddition, called click chemistry, between unnatural N-acetylglucosamine (GlcNAc) analogues (substituted with an azido or alkyne group) and the corresponding biotinylated probe to specifically detect, enrich and identify O-GlcNAc-modified proteins. This bio-orthogonal conjugation confirms that only azido analogue of GlcNAc is metabolized by the cell. Thanks to the biotin probe, affinity purification on streptavidin beads allowed us to identify 32 O-GlcNAc-azido-tagged proteins by LC-MS/MS analysis in an MCF-7 cellular model, 14 of which were previously unreported. This work illustrates the use of the click-chemistry-based strategy combined with a proteomic approach to get further insight into the pattern of O-GlcNAc-modified proteins and the biological significance of this post-translational modification. Figure Detection of biotinylated O-GlcNAz proteins in MCF-7 cells Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Caroline Gurcel and Anne-Sophie Vercoutter-Edouart contributed equally to this work.     

Sur Les Partitions en Chaînes du Graphe Divisoriel

On path partitions of the divisor graph. Let D(x) be the graph with vertices {1, 2, ..., ⌊x⌋} whose edges come from the division relation, and let D(x, y) be the subgraph restricted to the integers with prime factors less than or equal to y. We give sufficient conditions on x and y for the graph D(x, y) to be Hamiltonian. We deduce an asymptotic formula for the number of paths in D(x) needed to partition the set of vertices {1, 2, ..., ⌊x⌋}.

     

<Emphasis Type="Italic">L</Emphasis><Superscript><Emphasis Type="Italic">q</Emphasis></Superscript>-Functional Inequalities and Weighted Porous Media Equations

Using measure-capacity inequalities we study new functional inequalities, namely L ^q -Poincaré inequalities

Polybenzimidazole‐decorated carbon nanotube: A high‐performance proton conductor

Interaction between negatively charged Nafion^® and a positively charged polybenzimidazole‐decorated carbon nanotube leads to the formation of an ionic complex with high charge density for proton conduction, which can lead to an improvement in transport properties. Here we investigate the high‐temperature and low‐humidity proton conductivity of this nanocomposite membrane as a potential membrane for fuel cell applications.

     

White fluorescence from core-shell silica nanoparticles

Into the white: Encapsulation of a naphthalimide moiety in the core of silica nanoparticles afforded nanospheres with a strong green excimeric emission. Together with the blue emission of the monomeric naphthalimide and the yellow fluorescence of the tetrazine acceptor on the outer shell, the added contributions provide intense white fluorescence upon 330?nm UV excitation.     

In vitro inhibitory properties of ferrocene-substituted chalcones and aurones on bacterial and human cell cultures

Two series of ten chalcones and ten aurones, where ferrocene replaces the C ring and with diverse substituents on the A ring were synthesized. The compounds were tested against two antibiotic-sensitive bacterial strains, E. coli ATCC 25922 and S. aureus ATCC 25923, and two antibiotic-resistant strains, S. aureus SA-1199B and S. epidermidis IPF896. The unsubstituted compound and those with methoxy substitution showed an inhibitory effect on all bacterial strains at minimum inhibitory concentrations ranging between 2 and 32 mg L(-1). For four of these compounds, the effect was bactericidal, as opposed to bacteriostatic. The corresponding organic aurones did not show growth inhibition, underscoring the role of the ferrocene group. The methoxy-substituted aurones and the unsubstituted aurone also showed low micromolar (IC(50)) activity against MRC-5 non-tumoral lung cells and MDA-MB-231 breast cancer cells, suggesting non-specific toxicity.     

Structural Evolution during geopolymerization from an early age to consolidated material

Time-resolved rheology, small angle X-ray scattering (SAXS), and electron paramagnetic resonance (EPR) techniques were used to study the polymerization of geopolymers. These polymers are inorganically synthesized by the alkaline activation of an aluminosilicate source (metakaolin) in aqueous solution. The influence of the alkali activator (Na(+), K(+), and Cs(+)) was investigated at room temperature. As observed through the variation of the viscoelastic moduli (G', G"), curing proceeds in steps that are well pronounced when NaOH is used. These steps correspond to a specific dissolution/polycondensation mechanism and are smoothed when the size of the alkali cations increases. This size effect also has an impact on the gelation time (maximum of tan δ). Structural analysis through SAXS experiments allows us to characterize these mechanisms on the nanoscale and to show that the growth of the geopolymer is due to the aggregation of oligomers with a size that is even smaller than the cation is chaotropic. Finally, water behavior during geopolymerization was assessed by using a spin probe. The results show that the spin-probe signal progressively disappears during the first moment of the reaction and reappears when the solid polymeric gel is formed, highlighting the role of water molecules in the different chemical reactions during the process. The EPR signal is in fact increasingly masked as the ion size decreases (because of the strength of the hydration shell). At the end of the reaction, some water molecules were released within the pores, restoring the visibility of the isotropic spin-probe signal.     

Permanent Polymer Coating for in vivo MRI Visualization of Tissue Reinforcement Prostheses

The clinical advantage of MRI visualization of prostheses in soft tissue prolapses is very appealing as over 1 000 000 MRI‐transparent synthetic meshes are implanted annually, and postoperative complications such as mesh shrinkage and migration are frequent. Here, the synthesis of a new material composed of a DTPA‐Gd complex grafted onto a backbone of PMA via a covalent bond is described (DTPA‐Gd‐PMA). This new polymer is sprayed onto meshes and gives an MR signal for a long period without any significant release of Gd. In vitro cytocompatibility tests on fibroblasts show limited cytotoxicity. Microscopic investigations indicate that vital cells rapidly colonize the material. Finally, coated meshes implanted in rats are easily recognizable using an MR imaging system.