27 research outputs found

    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

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    In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

    La renovación de la palabra en el bicentenario de la Argentina : los colores de la mirada lingüística

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    El libro reúne trabajos en los que se exponen resultados de investigaciones presentadas por investigadores de Argentina, Chile, Brasil, España, Italia y Alemania en el XII Congreso de la Sociedad Argentina de Lingüística (SAL), Bicentenario: la renovación de la palabra, realizado en Mendoza, Argentina, entre el 6 y el 9 de abril de 2010. Las temáticas abordadas en los 167 capítulos muestran las grandes líneas de investigación que se desarrollan fundamentalmente en nuestro país, pero también en los otros países mencionados arriba, y señalan además las áreas que recién se inician, con poca tradición en nuestro país y que deberían fomentarse. Los trabajos aquí publicados se enmarcan dentro de las siguientes disciplinas y/o campos de investigación: Fonología, Sintaxis, Semántica y Pragmática, Lingüística Cognitiva, Análisis del Discurso, Psicolingüística, Adquisición de la Lengua, Sociolingüística y Dialectología, Didáctica de la lengua, Lingüística Aplicada, Lingüística Computacional, Historia de la Lengua y la Lingüística, Lenguas Aborígenes, Filosofía del Lenguaje, Lexicología y Terminología

    Liquid crystalline textures and polymer morphologies resulting from electropolymerisation in liquid crystal phases

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    Artículo de publicación ISISin acceso a texto completoA small fraction of an acrylate liquid crystalline monomer (<= 5%) is mixed into nematic and smectic liquid crystalline phases, and polymerised through the application of a voltage (electropolymerisation). Polarising optical microscopy reveals that the textures during polymerisation are templated through stabilisation via the forming polymer. During polymerisation in the nematic phase, the director can be observed to gradually reorient into the field-on state. Scanning electron microscopy reveals rope-like and corrugated structures of a distinctive periodicity (500-750 nm). Quite different polymer structures are formed by electropolymerisation in the smectic phase, such as micron-scale worm-like objects that agglomerate reversibly as the temperature changes.Conicyt Fondecyt Project 1130187 NowNano Progra

    Incommensurate structures investigated by X-ray studies of electropolymerised methacrylic monomer with TiO2 nanoparticles

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    We explore the possibility of producing polymer nanocomposites with an ordered distribution of nanoparticles by using an electropolymerizable liquid crystal (LC) monomer. The nanoparticles are added to the monomer before polymerizing it. We study the polymer derived from the LC (E)-6-(3-hydroxy-4-(((4-octyloxy)phenyl)imino)methyl)phenoxy)hexyl methacrylate (M6R8) both pure and in the presence of 3.4nm TiO2 nanoparticles, at 30wt%. This particular system is chosen since (1) the LC polymers we work with have the added advantage of having a specific orientation and structure which allows us to study its effect in the nanoparticles and (2) when considering the nanocomposite, it is polymerized with the nanoparticles included. The system is studied using grazing incidence small angle X-ray scattering and in-plane direction X-ray scattering. The polymer obtained alone appears to be tilted with respect to the surface of the substrate. The structure adopted by the nanoparticles in the nanocomposite is layered and apparently incommensurate with the polymer. It is formed through the association of the nanoparticles with the M6R8 aromatic cores during the process of electropolymerisation. This interpretation of the data is supported by the nanoparticle structures formed when the related, non-polymerizable LC, (E)-6-(3-hydroxy-4-(((4-octyloxy)phenyl)imino)methyl)phenoxy)hexyl isobutyrate (I6R8), is analysed. We find that for both, the pure polymer poly-((E)-6-(3-hydroxy-4-(((4-octyloxy)phenyl)imino)methyl)phenoxy)hexyl) methacrylate (EPM6R8) as well as the polymer with nanoparticles (EPM6R830TO), the electropolymerisation imposes a preferred growth direction of the polymer side chains, and therefore for the nanoparticle arrangement in the polymer.CONICYT 21130413 21090713 Fondecyt 1130187 NSF NSF-OISE-115758

    Influence of NH-S gamma bonding interactions on the structure and dynamics of metallothioneins

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    Mammalian metallothioneins ([Formula: see text]) show a clustered arrangement of the metal ions and a nonregular protein structure. The solution structures of Cd(3)-thiolate cluster containing beta-domain of mouse beta-MT-1 and rat beta-MT-2 show high structural similarities, but widely differing structure dynamics. Molecular dynamics simulations revealed a substantially increased number of NH-Sgamma hydrogen bonds in beta-MT-2, features likely responsible for the increased stability of the Cd(3)-thiolate cluster and the enfolding protein domain. Alterations in the NH-Sgamma hydrogen-bonding network may provide a rationale for the differences in dynamic properties encountered in the beta-domains of MT-1, -2, and -3 isoforms, believed to be essential for their different biological function
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