No abstract

Prosaposin, the precursor of saposins A, B, C, and D, was recently identified as a neurotrophic factor in vitro as well as in vivo. Its neurotrophic activity has been localized to a linear 12‐amino acid sequence located in the NH2‐terminal portion of the saposin C domain. In this study, we show the colocalization of prosaposin and ganglioside GM3 on NS20Y cell plasma membrane by scanning confocal microscopy. Also, TLC and western blot analyses showed that GM3 was specifically associated with prosaposin in immunoprecipitates; this binding was Ca2+‐independent and not disassociated during sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. The association of prosaposin‐GM3 complexes on the cell surface appeared to be functionally important, as determined by differentiation assays. Neurite sprouting, induced by GM3, was inhibited by antibodies raised against a 22‐mer peptide, prosaptide 769, containing the neurotrophic sequence of prosaposin. In addition, pertussis toxin inhibited prosaptide‐induced neurite outgrowth, as well as prosaptide‐enhanced ganglioside concentrations in NS20Y cells, suggesting that prosaposin acted via a G protein‐mediated pathway, affecting both ganglioside content and neuronal differentiation. Our findings revealed a direct and right GM3‐prosaposin association on NS20Y plasma membranes. We suggest that ganglioside‐protein complexes are structural components of the prosaposin receptor involved in cell differentiation.

Ultraviolet light can cause photodamage to the skin, such as sunburn and melanomas. TiO2 is introduced in sunscreen formulations to reflect and scatter UV radiation. However, it can also photocatalyze the production of reactive species like O 2 .and OH .. Here, we aimed to remove the photocatalytic activity of TiO2 (anatase and rutile), while preserving the UV filter property. Anatase and rutile were modified through two preparative protocols. The first used HCl lignin precipitation of ethylene glycol lignin solution in the presence of the cross-linker glutaraldehyde and anatase or rutile nanoparticles. The second protocol used HNO3 lignin precipitation of lignin aqueous solution in the presence of anatase or rutile nanoparticles. Both methodologies were performed at room temperature and ambient pressure in green media, with vigorous mixing followed by 20-kHz sonication. The composite materials obtained were fully characterized by SEM, XRD analysis and FT-IR spectroscopy, and their photostability, and photo and shielding activities were evaluated through reference reactions: oxidation of 2-propanol, an ene-reaction conducted on an α,β-unsaturated carboxylic derivative and photochemical transformation of o-nitrobenzaldehyde to o-nitrosobenzoic acid. Therefore, in the near future, industrial use of these new clusters can help to minimize TiO2 phototoxicity in sunscreen formulations, while preserving the sunscreen photoprotection activity.

No abstract

Due to the increasing resistance of microbial pathogens to the available drugs, the identification of new antimicrobial agents with a new mechanism of action is urgently needed. In this context, cationic antimicrobial peptides (AMPs) are considered promising candidates. Although there is evidence that, in contrast to conventional antibiotics, microbial membranes are the principal target of a large number of AMPs, thus making it difficult for the pathogen to acquire resistance, their mode(s) of action is not yet completely clear. Intense research is currently devoted to understand the effect(s) of AMPs on intact cells, either at sub-lethal or at lethal peptide concentrations, and fluorescence/electron microscopy techniques represent a valid tool to get insight into the damage caused by these molecules on the morphology and membrane structure of the target cell. We here present an overview of some microscopic methodologies to address this issue.