31 research outputs found
SIK1/SOS2 networks: decoding sodium signals via calcium-responsive protein kinase pathways
Changes in cellular ion levels can modulate distinct signaling networks aimed at correcting major disruptions in ion balances that might otherwise threaten cell growth and development. Salt-inducible kinase 1 (SIK1) and salt overly sensitive 2 (SOS2) are key protein kinases within such networks in mammalian and plant cells, respectively. In animals, SIK1 expression and activity are regulated in response to the salt content of the diet, and in plants SOS2 activity is controlled by the salinity of the soil. The specific ionic stress (elevated intracellular sodium) is followed by changes in intracellular calcium; the calcium signals are sensed by calcium-binding proteins and lead to activation of SIK1 or SOS2. These kinases target major plasma membrane transporters such as the Na+,K+-ATPase in mammalian cells, and Na+/H+ exchangers in the plasma membrane and membranes of intracellular vacuoles of plant cells. Activation of these networks prevents abnormal increases in intracellular sodium concentration
Clusters of galaxies : observational properties of the diffuse radio emission
Clusters of galaxies, as the largest virialized systems in the Universe, are
ideal laboratories to study the formation and evolution of cosmic
structures...(abridged)... Most of the detailed knowledge of galaxy clusters
has been obtained in recent years from the study of ICM through X-ray
Astronomy. At the same time, radio observations have proved that the ICM is
mixed with non-thermal components, i.e. highly relativistic particles and
large-scale magnetic fields, detected through their synchrotron emission. The
knowledge of the properties of these non-thermal ICM components has increased
significantly, owing to sensitive radio images and to the development of
theoretical models. Diffuse synchrotron radio emission in the central and
peripheral cluster regions has been found in many clusters. Moreover
large-scale magnetic fields appear to be present in all galaxy clusters, as
derived from Rotation Measure (RM) studies. Non-thermal components are linked
to the cluster X-ray properties, and to the cluster evolutionary stage, and are
crucial for a comprehensive physical description of the intracluster medium.
They play an important role in the cluster formation and evolution. We review
here the observational properties of diffuse non-thermal sources detected in
galaxy clusters: halos, relics and mini-halos. We discuss their classification
and properties. We report published results up to date and obtain and discuss
statistical properties. We present the properties of large-scale magnetic
fields in clusters and in even larger structures: filaments connecting galaxy
clusters. We summarize the current models of the origin of these cluster
components, and outline the improvements that are expected in this area from
future developments thanks to the new generation of radio telescopes.Comment: Accepted for the publication in The Astronomy and Astrophysics
Review. 58 pages, 26 figure
Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)
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