A phase of liposomes with entangled tubular vesicles

An equilibrium phase belonging to the family of bilayer liposomes in ternary mixtures of dimyristoylphosphatidylcholine (DMPC), water, and geraniol (a biological alcohol derived from oil-soluble vitamins that acts as a cosurfactant) has been identified. Electron and optical microscopy reveal the phase, labeled Ltv, to be composed of highly entangled tubular vesicles. In situ x-ray diffraction confirms that the tubule walls are multilamellar with the lipids in the chain-melted state. Macroscopic observations show that the Ltv phase coexists with the well-known L4 phase of spherical vesicles and a bulk L alpha phase. However, the defining characteristic of the Ltv phase is the Weissenberg rod climbing effect under shear, which results from its polymer-like entangled microstructure

Lamellar Phase of Stacked Two-Dimensional Rafts of Actin Filaments

We examined liquid crystalline phases of the cytoskeletal polyelectrolyte filamentous (F-)actin in the presence of multivalent counterions. As a function of increasing ion concentration, the F-actin rods in either an isotropic or a nematic phase will transform into a new and unexpected lamellar phase of crosslinked rafts (LXR phase), before condensing into a bundled phase of parallel, close-packed rods. This behavior is generic for alkali earth divalent ions Mg2+, Ca2+, Sr2+, and Ba2+, and the structural transitions are achieved without any architecture-specific actin-binding linker proteins