Cholesterol transport from late endosomes to the Golgi regulates t-SNARE trafficking, assembly, and function

Cholesterol regulates plasma membrane (PM) association and functioning of syntaxin-4 and soluble N-ethylmaleimide-sensitive fusion protein 23 (SNAP23) in the secretory pathway. However, the molecular mechanism and cellular cholesterol pools that determine the localization and assembly of these target membrane SNAP receptors (t-SNAREs) are largely unknown. We recently demonstrated that high levels of annexin A6 (AnxA6) induce accumulation of cholesterol in late endosomes, thereby reducing cholesterol in the Golgi and PM. This leads to an impaired supply of cholesterol needed for cytosolic phospholipase A2 (cPLA2) to drive Golgi vesiculation and caveolin transport to the cell surface. Using AnxA6-overexpressing cells as a model for cellular cholesterol imbalance, we identify impaired cholesterol egress from late endosomes and diminution of Golgi cholesterol as correlating with the sequestration of SNAP23/syntaxin-4 in Golgi membranes. Pharmacological accumulation of late endosomal cholesterol and cPLA2 inhibition induces a similar phenotype in control cells with low AnxA6 levels. Ectopic expression of Niemann-Pick C1 (NPC1) or exogenous cholesterol restores the location of SNAP23 and syntaxin-4 within the PM. Importantly, AnxA6-mediated mislocalization of these t-SNAREs correlates with reduced secretion of cargo via the SNAP23/syntaxin-4¿dependent constitutive exocytic pathway. We thus conclude that inhibition of late endosomal export and Golgi cholesterol depletion modulate t-SNARE localization and functioning along the exocytic pathway.

Colloidal assembly on magnetically vibrated stripes

We investigate the collective organization of paramagnetic colloidal particles externally driven above the periodic stripes of a uniaxial ferrimagnetic garnet film. An external field modulation induces vibration of the stripe walls and produces random motion of the particles. Defects in the stripe pattern break the symmetry of the potential and favor particle nucleation into large clusters above a critical density. Mismatch between particle size and pattern wavelength generates assemblies with different morphological order. At even higher field strengths, repulsive dipolar interactions between the particles induce cluster melting. We propose a novel approach to generate and externally control a variety of colloidal assemblies.

Self-organizing propagation patterns from dynamic self-assembly in monolayers

Propagation of localized orientational waves, as imaged by Brewster angle microscopy, is induced by low intensity linearly polarized light inside axisymmetric smectic-C confined domains in a photosensitive molecular thin film at the air/water interface (Langmuir monolayer). Results from numerical simulations of a model that couples photoreorientational effects and long-range elastic forces are presented. Differences are stressed between our scenario and the paradigmatic wave phenomena in excitable chemical media.

Self-organizing propagation patterns from dynamic self-assembly in monolayers

Propagation of localized orientational waves, as imaged by Brewster angle microscopy, is induced by low intensity linearly polarized light inside axisymmetric smectic-C confined domains in a photosensitive molecular thin film at the air/water interface (Langmuir monolayer). Results from numerical simulations of a model that couples photoreorientational effects and long-range elastic forces are presented. Differences are stressed between our scenario and the paradigmatic wave phenomena in excitable chemical media.

Réseau d'Enseignement Multimédia (REM): a la recerca d'un Erasmus virtual

El desenvolupament de les telecomunicacions mitjanyant xarxes d"ordinadors com Internet, i la facilitat de l"ús d'aquest tipus de xarxes, incrementen la possibilitat tant de transmetre material educatiu i intercanviar experiéncies com d"obrir nous canals de comunicació i crear entorns d"aprenentatge que permetin ultrapassar les coordenades d"espai i temps en qué s"han mogut tradicionalment les institucions. La Unió Europea, en el seu intent d"apropar les diferents cultures que conformen el mapa de la nostra comunitat, s"interessa per aquest tipus de sistemes, que permeten la comunicació i l"accés a la informació independentment de l"espai i del temps.

El entorno virtual de la Universitat d'Andorra: la visión del profesorado

En los últimos años las Universidades tradicionalmente presenciales han apostado por la incorporación de la tecnología en los procesos académicos, muestra de ello es la proliferación de campus virtuales que acogen entornos virtuales de aprendizaje. La Universitat d"Andorra utiliza un entorno virtual de aprendizaje desde hace 8 años. El presente trabajo analiza los usos del entorno por parte del profesorado con el objetivo de proponer mejoras que reviertan en la mejora del aprendizaje por parte de los estudiantes. Se ha seguido una metodología descriptiva que combina técnicas cuantitativas y técnicas cualitativas, se ha distribuido un cuestionario dirigido al profesorado y se han realizado dos grupos de discusión dirigidos a profesores y estudiantes respectivamente. Los resultados de este estudio han permitido identificar las necesidades de formación del profesorado de la Universitat d"Andorra y realizar un plan de acciones para la mejora del uso del entorno virtual que en el momento de hacer el estudio prácticamente se reducía a una herramienta de compartición de documentación.

Model studies on the synthesis of madangamine alkaloids. Assembly of the macrocyclic rings

Using simplified model derivatives, the assembly of the macrocyclic rings of madangamines, including the 13- and 14-membered D rings of madangamines C-E, the all-cis-triunsaturated 15-membered D ring of madangamine A, and the (Z,Z)-unsaturated 11-membered E ring common to madangamines A-E, has been studied.

Assessment of emotional reactivity produced by exposure to virtual environments in patients with eating disorders

The aim of this study was to assess the usefulness of virtual environments representing situations that are emotionally significant to subjects with eating disorders (ED). These environments may be applied with both evaluative and therapeutic aims and in simulation procedures to carry out a range of experimental studies. This paper is part of a wider research project analyzing the influence of the situation to which subjects are exposed on their performance on body image estimation tasks. Thirty female patients with eating disorders were exposed to six virtual environments: a living-room (neutral situation), a kitchen with highcalorie food, a kitchen with low-calorie food, a restaurant with high-calorie food, a restaurant with low-calorie food, and a swimming-pool. After exposure to each environment the STAI-S (a measurement of state anxiety) and the CDB (a measurement of depression) were administered to all subjects. The results show that virtual reality instruments are particularly useful for simulating everyday situations that may provoke emotional reactions such as anxiety and depression, in patients with ED. Virtual environments in which subjects are obliged to ingest high-calorie food provoke the highest levels of state anxiety and depression.

Educació virtual : Els dispositius mòbils com a eina d'ensenyament-aprenentatge

Aquest treball pretén aprofundir en com es poden aprofitar les noves eines tecnològiques per millorar l'entorn educatiu. Analitzarem de quina manera els dispositius mòbils poden ajudar a incrementar la motivació, la curiositat i la cooperació dels alumnes i, en definitiva, l'aprentatge.

La gestión de los libros electrónicos en la Biblioteca Virtual de la UOC

El texto que se presenta muestra cómo se lleva a cabo la gestión de los libros electrónicos en la Biblioteca Virtual (en adelante BV) de la Universitat Oberta de Catalunya (en adelante UOC). La BV pone especial énfasis en la adquisición de libros digitales para mejorar el acceso de los usuarios a los recursos y a lascolecciones de una universidad caracterizada por su virtualidad. El documento presenta, en primer lugar, el entorno en el que se adquieren y se utilizan los libros electrónicos: se describen los distintos escenarios de adquisición en los que se puede encontrar la BV y se definen los circuitos internos que permiten su gestión, así como los procesos técnicos de los documentos. A continuación, se muestran las distintas opciones de acceso y consulta de libros electrónicos que actualmente se ofrecen desde la BV y se exponenlos análisis de uso de dichos documentos. Por último, se presentan las conclusiones a las que llega la BV sobre el nuevo contexto de libros electrónicos.

Programari de consulta offline al campus virtual de la UOC

L'objectiu del projecte és el desenvolupament d'una aplicació d'escriptori que permeti a l'estudiant la consulta offline de les darreres novetats disponibles a les aules del campus UOC. Es tracta d'automatitzar el procés de consulta i descàrrega local de dades per tal de poder consultar-les posteriorment fora de línia.

Projecte de botiga virtual de XsysPC

El projecte es basa en el desenvolupament d'una aplicació web per a la companyia fictícia XsysPC que ha decidit oferir la venta per Internet dels productes que tenen en les seves botigues, tals com ordinadors, components informàtics, perifèrics i altres.

Tenda Virtual

Aquest projecte està principalment destinat a aconseguir un bon maneig d'algunes de les eines involucrades en aquest tema, com són JSP, TOMCAT i Struts 2 per a les necessitats web i MySQL per al registre de materials i transaccions.

Projecte de botiga virtual de XsysPC

El projecte es basa en el desenvolupament d'una aplicació web per a la companyia fictícia XsysPC que ha decidit oferir la venta per Internet dels productes que tenen en les seves botigues, tals com ordinadors, components informàtics, perifèrics i altres.

Spanish E-Consumer Segmentation and Positioning in Virtual Supermarkets Sector

This article analyses different factors that influence the purchasing behaviour of online supermarket customers. These factors are related to both the appearance of the website as well as the processes that take place when making the purchase. Based on these analyses, the various groups of consumers with homogenous behaviour are studied and positioned according to their attitudes. The analysis also allows the quality of the service offered by this kind of establishment to be defined, as well as the main dimensions in which it develops. In the conclusions, factors which should influence the manager of an online supermarket to improve the quality of its service are given