Extracellular vesicles are a heterogeneous group of cell-derived membranous structures comprising exosomes and microvesicles, which originate from the endosomal system or which are shed from the plasma membrane, respectively They are present in biological fluids and are involved in multiple physiological and pathological processes Extracellular vesicles are now considered as an additional mechanism for intercellular communication, allowing cells to exchange proteins, lipids and genetic material Knowledge of the cellular processes that govern extracellular vesicle biology is essential to shed light on the physiological and pathological functions of these vesicles as well as on clinical applications involving their use and/or analysis However, in this expanding field, much remains unknown regarding the origin, biogenesis, secretion, targeting and fate of these vesicles

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Shedding light on the cell biology of extracellular vesicles.

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Degradable Controlled-Release Polymers and Polymeric Nanoparticles: Mechanisms of Controlling Drug Release

Water gelation by small organic molecules.

Comprehensive global climate models1 are the only tools that account for the complex set of processes which will determine future climate change at both a global and regional level. Planners are typically faced with a wide range of predicted changes from different models of unknown relative quality2,3, owing to large but unquantified uncertainties in the modelling process4. Here we report a systematic attempt to determine the range of climate changes consistent with these uncertainties, based on a 53-member ensemble of model versions constructed by varying model parameters. We estimate a probability density function for the sensitivity of climate to a doubling of atmospheric carbon dioxide levels, and obtain a 5–95 per cent probability range of 2.4–5.4 °C. Our probability density function is constrained by objective estimates of the relative reliability of different model versions, the choice of model parameters that are varied and their uncertainty ranges, specified on the basis of expert advice. Our ensemble produces a range of regional changes much wider than indicated by traditional methods based on scaling the response patterns of an individual simulation5,6.

Quantification of modelling uncertainties in a large ensemble of climate change simulations

Membrane proteins, lipids and detergents: not just a soap opera

Reconstitution of membrane proteins into liposomes: application to energy-transducing membrane proteins.

Bio-Beads: An Efficient Strategy for Two-Dimensional Crystallization of Membrane Proteins

Detergent removal from lipid-protein-detergent micellar solutions is the most successful strategy for reconstitution of integral membrane proteins into proteoliposomes or into two-dimensional crystals. This review establishes the potential of polystyrene beads as a simple alternative to other conventional detergent removing strategies such as dialysis, gel chromatography and dilution. Kinetics and equilibrium aspects of removal of different detergents by hydrophobic adsorption onto polystyrene beads have been systematically investigated. A mechanism of adsorption onto polystyrene beads is proposed and provide useful information about the use of these beads in reconstitution experiments. The usefulness of this detergent removal strategy to produce quasi-ideal proteoliposomes is evaluated by considering the morphology and the size of the reconstituted vesicles, the homogeneity in size and protein distribution, the final protein orientation and the permeability of resulting proteoliposomes. Finally, the advantages of detergent removal by polystyrene beads as an alternative to conventional dialysis in two-dimensional crystallization trials are evaluated through review of recent structural reconstitution studies.

Detergent removal by non-polar polystyrene beads

We report the first experimental evidence of the effect of the activity of transmembrane proteins on shape fluctuations of a lipid membrane. We incorporate a light-driven proton pump, the bacteriorhodopsin (BR), inside the phospholipid bilayer of fluctuating giant vesicles. Using the micropipet technique, we measure the excess surface area due to the fluctuations of the vesicles. The excess surface area is larger when the BR pumps protons than when it is not activated.

Daniel Lévy

Papers

Reconstitution of membrane proteins into liposomes: application to energy-transducing membrane proteins.

Bio-Beads: An Efficient Strategy for Two-Dimensional Crystallization of Membrane Proteins

Detergent removal by non-polar polystyrene beads

Activity of Transmembrane Proteins Induces Magnification of Shape Fluctuations of Lipid Membranes

High-resolution AFM of membrane proteins directly incorporated at high density in planar lipid bilayer.