Specific Anion and Cation Binding to Lipid Membranes Investigated on a Solid Supported Membrane

Ion binding to a lipid membrane is studied by application of a rapid soln. exchange on a solid supported membrane. The resulting charge displacement is analyzed in terms of the affinity of the applied ions to the lipid surface. The authors find that chaotropic anions and kosmotropic cations are attracted to the membrane independent of the membrane compn. In particular, the same behavior is found for lipid headgroups bearing no charge, like monoolein. This general trend is modulated by electrostatic interaction of the ions with the lipid headgroup charge. These results cannot be explained with the current models of specific ion interactions

Differentiation of mouse embryonic stem cells into a defined neuronal lineage

Although it has long been known that cultured embryonic stem cells can generate neurons, the lineage relationships with their immediate precursors remain unclear. We report here that selection of highly proliferative stem cells followed by treatment with retinoic acid generated essentially pure precursors that markers identified as Pax-6-positive radial glial cells. As they do in vivo, these cells went on to generate neurons with remarkably uniform biochemical and electrophysiological characteristics

Spontaneous Formation of Bilayers and Vesicles in Mixtures of Single-Chain Alkyl Carboxylates: Effect of pH and Aging and Cytotoxicity Studies

We report the observation of bilayer fragments, some of which close to form vesicles, over a large range of pH at room temp. from mixts. of single-chain biocompatible com. available nontoxic alkyl carboxylic surfactants after neutralization with HCl. The pH at which the morphol. transitions occur is varied only by changing the ratio between two surfactants: the alkyloligoethyleneoxide carboxylate and sodium laurate. The effect of aging of the mixed surfactant systems in the pH region desired for dermatol. application (4.5 < pH < 7) is also studied. Finally, we show results of cytotoxicity studies on the surfactant mixts

Diversity and distribution Patterns of the infralittoral green macroalgae from Potiguar basin, Rio Grande do Norte, Northeastern Brazil

Diversity and distribution pattern of the infralittoral green macroalgae at Potiguar basin, Rio Grande do Norte, Northeastern Brazil were analyzed from material collected at depths varying from 2 to 100 m. Collections were carried out with two types of dredges during four campaigns: July 2002, May and November 2003 and May 2004 at 43 stations. Chlorophyta is represented by 54 species, five varieties and three forms. The most representative family is Caulerpaceae, and the most diverse genus is Caulerpa, with 11 species. The results showed that most taxa (89%) are rare, and 10% are present at low frequencies. The most frequent species was Caulerpaprolifera (Forssk.) J.V. Lamour. occurring at almost all coastal and inner shelf stations, recorded in all campaigns. Species distribution by depth range showed that higher species number occurred on the inner shelf from 10 to 20 m, and a wide vertical distribution pattern was registered for Anadyomenestellata (Wulfen in Jacq.) C. Agardh,Chamaedoris peniculum (J. Ellis &amp; Solander) Kuntze, Codium isthmocladum Vickers, Microdictyon sp., Udoteaoccidentalis A. Gepp &amp; E. Gepp and Ventricaria ventricosa (J. Agardh) J.L. Olsen &amp; J.A. West. Four species, Cladophoracoelothrix Kütz., C.ordinata (Børgensen) C. Hoek, Caulerpellaambigua (Okamura) Prud'homme &amp; Lokhorst and Halimedasimulans M. Howe, were recorded for the first time in Rio Grande do Norte