Anisotropic cellular forces support mechanical integrity of the Stratum Corneum barrier.

The protective function of biological surfaces that are exposed to the exterior of living organisms is the result of a complex arrangement and interaction of cellular components. This is the case for the most external cornified layer of skin, the stratum corneum (SC). This layer is made of corneocytes, the elementary 'flat bricks' that are held together through adhesive junctions.

Egg CD9 protein tides correlated with sperm oscillations tune the gamete fusion ability in mammal.

Mammalian fertilization involves membrane events-adhesion, fusion, sperm engulfment, membrane block to polyspermy-whose causes remain largely unknown. Recently, specific oscillations of the sperm in contact with the egg were shown to be necessary for fusion. Using a microfluidic chip to impose the venue for the encounter of two gametes allowed real-time observation of the membrane remodelling occurring at the sperm/egg interface.

A specific flagellum beating mode for inducing fusion in mammalian fertilization and kinetics of sperm internalization.

The salient phases of fertilization are gamete adhesion, membrane fusion, and internalization of the spermatozoon into the oocyte but the precise timeline and the molecular, membrane and cell mechanisms underlying these highly dynamical events are far from being established. The high motility of the spermatozoa and the unpredictable location of sperm/egg fusion dramatically hinder the use of real time imaging optical techniques that should directly provide the dynamics of cell events. Using an approach based on microfluidics technology, the sperm/egg interaction zone was imaged with the best front view, and the timeline of the fertilization events was established with an unparalleled temporal accuracy from the onset of gamete contact to full sperm DNA decondensation.

Snapshot of sequential SNARE assembling states between membranes shows that N-terminal transient assembly initializes fusion.

Many prominent biological processes are driven by protein assembling between membranes. Understanding the mechanisms then entails determining the assembling pathway of the involved proteins. Because the intermediates are by nature transient and located in the intermembrane space, this determination is generally a very difficult, not to say intractable, problem.

Binding of sperm protein Izumo1 and its egg receptor Juno drives Cd9 accumulation in the intercellular contact area prior to fusion during mammalian fertilization.

Little is known about the molecular mechanisms that induce gamete fusion during mammalian fertilization. After initial contact, adhesion between gametes only leads to fusion in the presence of three membrane proteins that are necessary, but insufficient, for fusion: Izumo1 on sperm, its receptor Juno on egg and Cd9 on egg. What happens during this adhesion phase is a crucial issue.

Interfacial pressure and phospholipid density at emulsion droplet interface using fluorescence microscopy.

Phospholipids are widely used to stabilize oil in water micron size emulsion droplets; the interfacial phospholipid density and tension of such droplets are difficult to estimate. In the present paper, we describe a simple approach by which the measurement of a micron size oil droplet interface fluorescence intensity provides directly both the interfacial phospholipid density and the interfacial tension. This method relies on two prior calibration steps: (i) the quantitative variation of the interfacial tension with fluorescence intensity at droplets interface through micro-manipulation techniques; (ii) the variation of interfacial tension with phospholipid density through monolayer isotherm.

Homotypic and heterotypic adhesion induced by odorant receptors and the β2-adrenergic receptor.

In the mouse olfactory system regulated expression of a large family of G Protein-Coupled Receptors (GPCRs), the Odorant Receptors (ORs), provides each sensory neuron with a single OR identity. In the wiring of the olfactory sensory neuron projections, a complex axon sorting process ensures the segregation of >1,000 subpopulations of axons of the same OR identity into homogeneously innervated glomeruli. ORs are critical determinants in axon sorting, and their presence on olfactory axons raises the intriguing possibility that they may participate in axonal wiring through direct or indirect trans-interactions mediating adhesion or repulsion between axons.

CD9 tetraspanin generates fusion competent sites on the egg membrane for mammalian fertilization.

CD9 tetraspanin is the only egg membrane protein known to be essential for fertilization. To investigate its role, we have measured, on a unique acrosome reacted sperm brought in contact with an egg, the adhesion probability and strength with a sensitivity of a single molecule attachment. Probing the binding events at different locations of wild-type egg we described different modes of interaction.

Mapping mouse gamete interaction forces reveal several oocyte membrane regions with different mechanical and adhesive properties.

This study focuses on the interaction involved in the adhesion of mouse gametes and on the mechanical properties of the oocyte membrane. The oocyte has an asymmetrical shape, and its membrane is composed of two distinct areas. One is rich in microvilli, and the other is smoother and without microvilli.

Creation of intercellular bonds by anchoring protein ligands to membranes using the diphtheria toxin T domain.

We describe the creation of cell adhesion mediated by cell surface engineering. The Flt3-ligand was fused to a membrane anchor made of the diphtheria toxin translocation domain. The fusion protein was attached to the surface of a cell by an acid pulse.

Structure and properties of hydrophobically end-capped poly(ethylene oxide) solutions in the presence of monovalent and divalent cations.

Hydrophobically modified poly(ethylene oxide), HMPEO, was studied in concentrated salt solutions. The influence of salts was compared to the effect of temperature on poly(ethylene oxide), PEO. As expected, the addition of monovalent cations (Na(+), K(+)) has the same effect as an increase in temperature in agreement with the thermodynamic properties of PEO: a decrease in solubility, micelle size, and viscosity was observed.

Specific and non specific interactions involving Le( X ) determinant quantified by lipid vesicle micromanipulation.

Carbohydrate-carbohydrate recognition is emerging today as an important type of interaction in cell adhesion. One Ca(2+)mediated homotypic interaction between two Lewis( X ) determinants (Le( X )) has been proposed to drive cell adhesion in murine embryogenesis. Here, the adhesion energies of lipid vesicles functionalized with glycolipids bearing monomeric or dimeric Le( X ) determinants were measured in NaCl or CaCl(2) media with the micropipette aspiration technique.