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Plos Biology : Down-regulation of Nf-κb Target Genes by the Ap-1 a...

By: David S. Schneider

Description : The activation of several transcription factors is required for the elimination of infectious pathogens via the innate immune response. The transcription factors NF-jB, AP-1, and STAT play major roles in the synthesis of immune effector molecules during innate immune responses. However, the fact that these immune responses can have cytotoxic effects requires their tight regulation to achieve restricted and transient activation, and mis-regulation of the dam...

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Plos Biology : Activator Control of Nucleosome Occupancy in Activa...

By: Gene O. Bryant

Description : The relationship between chromatin structure and gene expression is a subject of intense study. The universal transcriptional activator Gal4 removes promoter nucleosomes as it triggers transcription, but how it does so has remained obscure. The reverse process, repression of transcription, has often been correlated with the presence of nucleosomes. But it is not known whether nucleosomes are required for that effect. A new quantitative assay describes, for ...

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Plos Biology : from Creation to Consolidation ; a Novel Framework ...

By: Edwin M. Robertson
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Plos Biology : Synthetic Associations Are Unlikely to Account for ...

By: Public Library of Science (Plos)
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Plos Biology : Tracing Personalized Health Curves During Infection...

By: Public Library of Science (Plos)

Description : It is difficult to describe host– microbe interactions in a manner that deals well with both pathogens and mutualists. Perhaps a way can be found using an ecological definition of tolerance, where tolerance is defined as the dose response curve of health versus parasite load. To plot tolerance, individual infections are summarized by reporting the maximum parasite load and the minimum health for a population of infected individuals and the slope of the resu...

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Plos Biology : Neuronal Expression of Glucosylceramide Synthase in...

By: Stephen O’rahilly

Description : Hypothalamic neurons are main regulators of energy homeostasis. Neuronal function essentially depends on plasma membrane-located gangliosides. The present work demonstrates that hypothalamic integration of metabolic signals requires neuronal expression of glucosylceramide synthase (GCS: UDP-glucose:ceramide glucosyltransferase). As a major mechanism of central nervous system (CNS) metabolic control, we demonstrate that GCS-derived gangliosides interacting w...

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Plos Biology : More Than Just Access ; Delivering on a Network-ena...

By: J. Marie Hardwick
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Plos Biology : Skin-derived Tslp Triggers Progression from Epiderm...

By: Yong-jun Liu

Description : Asthma is a common allergic lung disease frequently affecting individuals with a prior history of eczema/atopic dermatitis (AD): however, the mechanism underlying the progression from AD to asthma (the so-called ‘‘atopic march’’) is unclear. Here we show that, like humans with AD, mice with skin-barrier defects develop AD-like skin inflammation and are susceptible to allergic asthma. Furthermore, we show that thymic stromal lymphopoietin (TSLP), overexpress...

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Plos Biology : Hiv Plays and Wins a Game of T Cell Brinkmanship, V...

By: Roland G. Roberts
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Plos Biology : Role of Translational Coupling in Robustness of Bac...

By: Andre Levchenko

Description : Chemotaxis allows bacteria to colonize their environment more efficiently and to find optimal growth conditions, and is consequently under strong evolutionary selection. Theoretical and experimental analyses of bacterial chemotaxis suggested that the pathway has been evolutionarily optimized to produce robust output under conditions of such physiological perturbations as stochastic intercellular variations in protein levels while at the same time minimizing...

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Plos Biology : Darwinian Evolution on a Chip, Volume 6

By: Brian M. Paegel

Description : Computer control of Darwinian evolution has been demonstrated by propagating a population of RNA enzymes in a microfluidic device. The RNA population was challenged to catalyze the ligation of an oligonucleotide substrate under conditions of progressively lower substrate concentrations. A microchip-based serial dilution circuit automated an exponential growth phase followed by a 10-fold dilution, which was repeated for 500 log-growth iterations. Evolution w...

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Plos Biology : Human Population Density and Extinction Risk in the...

By: Craig Moritz

Description : Understanding why some species are at high risk of extinction, while others remain relatively safe, is central to the development of a predictive conservation science. Recent studies have shown that a species’ extinction risk may be determined by two types of factors : intrinsic biological traits and exposure to external anthropogenic threats. However, little is known about the relative and interacting effects of intrinsic and external variables on extincti...

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Plos Biology : Coupling of a Core Post-translational Pacemaker to ...

By: Martha Merrow

Description : Cyanobacteria are the only model circadian clock system in which a circadian oscillator can be reconstituted in vitro. The underlying circadian mechanism appears to comprise two subcomponents : a post-translational oscillator (PTO) and a transcriptional/translational feedback loop (TTFL). The PTO and TTFL have been hypothesized to operate as dual oscillator systems in cyanobacteria. However, we find that they have a definite hierarchical interdependency—the...

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Plos Biology : Discrete States of a Protein Interaction Network Go...

By: Tom Misteli

Description : The cytoplasm of eukaryotic cells is thought to adopt discrete ‘‘states’’ corresponding to different steady states of protein networks that govern changes in subcellular organization. For example, in Xenopus eggs, the interphase to mitosis transition is induced solely by activation of cyclin-dependent kinase 1 (CDK1) that phosphorylates many proteins leading to a reorganization of the nucleus and assembly of the mitotic spindle. Among these changes, the lar...

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Plos Biology : the Hierarchy of Exon-junction Complex Assembly by ...

By: Tom Misteli

Description : Exon junction complexes (EJCs) link nuclear splicing to key features of mRNA function including mRNA stability, translation, and localization. We analyzed the formation of EJCs by the spliceosome, the physiological EJC assembly machinery. We studied a comprehensive set of eIF4A3, MAGOH, and BTZ mutants in complete or C-complex–arrested splicing reactions and identified essential interactions of EJC proteins during and after EJC assembly. These data establis...

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Plos Biology : Rab7 Associates with Early Endosomes to Mediate Sor...

By: Kai L. Simons

Description : Semliki forest virus (SFV) is internalized by clathrin-mediated endocytosis, and transported via early endosomes to late endosomes and lysosomes. The intracellular pathway taken by individual fluorescently labeled SFV particles was followed using immunofluorescence in untransfected cells, and by video-enhanced, triple-color fluorescence microscopy in live cells transfected with GFP- and RFP-tagged Rab5, Rab7, Rab4, and Arf1. The viruses progressed from Rab5...

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Plos Biology : Cytoneme-mediated Delivery of Hedgehog Regulates th...

By: Public Library of Science (Plos)

Description : Stem cells reside in specialised microenvironments, or niches, which often contain support cells that control stem cell maintenance and proliferation. Hedgehog (Hh) proteins mediate homeostasis in several adult niches, but a detailed understanding of Hh signalling in stem cell regulation is lacking. Studying the Drosophila female germline stem cell (GSC) niche, we show that Hh acts as a critical juxtacrine signal to maintain the normal GSC population of the...

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Plos Biology : a Protein Complex Containing the Conserved Swi2, Vo...

By: Peter Becker

Description : The conserved histone variant H2A.Z functions in euchromatin to antagonize the spread of heterochromatin. The mechanism by which histone H2A is replaced by H2A.Z in the nucleosome is unknown. We identified a complex containing 13 different polypeptides associated with a soluble pool of H2A.Z in Saccharomyces cerevisiae. This complex was designated SWR1-Com in reference to the Swr1p subunit, a Swi2/Snf2-paralog. Swr1p and six other subunits were found only i...

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Plos Biology : Unraveling the Molecular Basis for Regenerative Cel...

By: Shannon J. Odelberg
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Plos Biology : Aphid Thermal Tolerance is Governed by a Point Muta...

By: Charles Godfray

Description : Symbiosis is a ubiquitous phenomenon generating biological complexity, affecting adaptation, and expanding ecological capabilities. However, symbionts, which can be subject to genetic limitations such as clonality and genomic degradation, also impose constraints on hosts. A model of obligate symbiosis is that between aphids and the bacterium Buchnera aphidicola, which supplies essential nutrients. We report a mutation in Buchnera of the aphid Acyrthosiphon ...

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