Proceedings of the Natural Academy of Sciences

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Wetting and phase separation in soft adhesion [Applied Physical Sciences]

Tue, 11/24/2015 - 13:04
In the classic theory of solid adhesion, surface energy drives deformation to increase contact area whereas bulk elasticity opposes it. Recently, solid surface stress has been shown also to play an important role in opposing deformation of soft materials. This suggests that the contact line in soft adhesion should mimic...
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Topological mechanics of gyroscopic metamaterials [Applied Physical Sciences]

Tue, 11/24/2015 - 13:04
Topological mechanical metamaterials are artificial structures whose unusual properties are protected very much like their electronic and optical counterparts. Here, we present an experimental and theoretical study of an active metamaterial—composed of coupled gyroscopes on a lattice—that breaks time-reversal symmetry. The vibrational spectrum displays a sonic gap populated by topologically...
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Strength and ductility of nanostructured Ti [Applied Physical Sciences]

Tue, 11/24/2015 - 13:04
Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time...
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FTacV of YedY: Pyranopterin redox chemistry [Biochemistry]

Tue, 11/24/2015 - 13:04
A long-standing contradiction in the field of mononuclear Mo enzyme research is that small-molecule chemistry on active-site mimic compounds predicts ligand participation in the electron transfer reactions, but biochemical measurements only suggest metal-centered catalytic electron transfer. With the simultaneous measurement of substrate turnover and reversible electron transfer that is provided...
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Shifts in coral reef biogeochemistry [Environmental Sciences]

Tue, 11/24/2015 - 13:04
Oceanic uptake of anthropogenic carbon dioxide (CO2) has acidified open-ocean surface waters by 0.1 pH units since preindustrial times. Despite unequivocal evidence of ocean acidification (OA) via open-ocean measurements for the past several decades, it has yet to be documented in near-shore and coral reef environments. A lack of long-term...
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Xist imprinting by the unpaired state [Genetics]

Tue, 11/24/2015 - 13:04
The long noncoding X-inactivation–specific transcript (Xist gene) is responsible for mammalian X-chromosome dosage compensation between the sexes, the process by which one of the two X chromosomes is inactivated in the female soma. Xist is essential for both the random and imprinted forms of X-chromosome inactivation. In the imprinted form,...
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How online studies are transforming psych research [News Feature]

Tue, 11/24/2015 - 13:04
The samples are large and diverse, but will this trend strengthen the field or merely introduce new sources of error? After six weeks spent busily coding, psychology graduate student Brian Nosek finished his project in a cab on the way to the airport. When he landed in Seattle, he attended...
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Topological framework for local structure analysis [Applied Physical Sciences]

Tue, 10/27/2015 - 12:31
Physical systems are frequently modeled as sets of points in space, each representing the position of an atom, molecule, or mesoscale particle. As many properties of such systems depend on the underlying ordering of their constituent particles, understanding that structure is a primary objective of condensed matter research. Although perfect...
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Abrupt shifts in IPCC climate models [Earth, Atmospheric, and Planetary Sciences]

Tue, 10/27/2015 - 12:31
Abrupt transitions of regional climate in response to the gradual rise in atmospheric greenhouse gas concentrations are notoriously difficult to foresee. However, such events could be particularly challenging in view of the capacity required for society and ecosystems to adapt to them. We present, to our knowledge, the first systematic...
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Structure of nucleosomal barrier for transcription [Biochemistry]

Tue, 10/27/2015 - 12:31
Thousands of human and Drosophila genes are regulated at the level of transcript elongation and nucleosomes are likely targets for this regulation. However, the molecular mechanisms of formation of the nucleosomal barrier to transcribing RNA polymerase II (Pol II) and nucleosome survival during/after transcription remain unknown. Here we show that...
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Temporal evolution of helix hydration in ChR2 [Biophysics and Computational Biology]

Tue, 10/27/2015 - 12:31
The discovery of channelrhodopsins introduced a new class of light-gated ion channels, which when genetically encoded in host cells resulted in the development of optogenetics. Channelrhodopsin-2 from Chlamydomonas reinhardtii, CrChR2, is the most widely used optogenetic tool in neuroscience. To explore the connection between the gating mechanism and the influx...
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Species specificity of a ribosome from a pathogen [Biophysics and Computational Biology]

Tue, 10/27/2015 - 12:31
The emergence of bacterial multidrug resistance to antibiotics threatens to cause regression to the preantibiotic era. Here we present the crystal structure of the large ribosomal subunit from Staphylococcus aureus, a versatile Gram-positive aggressive pathogen, and its complexes with the known antibiotics linezolid and telithromycin, as well as with a...
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CD31 antagonizes extrinsic proapoptotic signals [Immunology and Inflammation]

Tue, 10/27/2015 - 12:31
Constitutive resistance to cell death induced by inflammatory stimuli activating the extrinsic pathway of apoptosis is a key feature of vascular endothelial cells (ECs). Although this property is central to the maintenance of the endothelial barrier during inflammation, the molecular mechanisms of EC protection from cell-extrinsic, proapoptotic stimuli have not...
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I{kappa}B{zeta} plays an important role in psoriasis [Immunology and Inflammation]

Tue, 10/27/2015 - 12:31
Psoriasis is a common immune-mediated, chronic, inflammatory skin disease characterized by hyperproliferation and abnormal differentiation of keratinocytes and infiltration of inflammatory cells. Although TNFα- and IL-17A–targeting drugs have recently proven to be highly effective, the molecular mechanism underlying the pathogenesis of psoriasis remains poorly understood. We found that expression of...
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Mycobacterial {alpha}-ketoglutarate dehydrogenase [Microbiology]

Tue, 10/27/2015 - 12:31
Enzymes of central carbon metabolism (CCM) in Mycobacterium tuberculosis (Mtb) make an important contribution to the pathogen’s virulence. Evidence is emerging that some of these enzymes are not simply playing the metabolic roles for which they are annotated, but can protect the pathogen via additional functions. Here, we found that...
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Gene therapy at late-stage retinal degeneration [Neuroscience]

Tue, 10/27/2015 - 12:31
Inherited retinal degenerations cause progressive loss of photoreceptor neurons with eventual blindness. Corrective or neuroprotective gene therapies under development could be delivered at a predegeneration stage to prevent the onset of disease, as well as at intermediate-degeneration stages to slow the rate of progression. Most preclinical gene therapy successes to...
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Mushroom bodies enable complex learning in bees [Neuroscience]

Tue, 10/27/2015 - 12:31
Learning theories distinguish elemental from configural learning based on their different complexity. Although the former relies on simple and unambiguous links between the learned events, the latter deals with ambiguous discriminations in which conjunctive representations of events are learned as being different from their elements. In mammals, configural learning is...
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Postsymptomatic ASOs in spinal muscular atrophy [Neuroscience]

Tue, 10/27/2015 - 12:31
Clinical presentation of spinal muscular atrophy (SMA) ranges from a neonatal-onset, very severe disease to an adult-onset, milder form. SMA is caused by the mutation of the Survival Motor Neuron 1 (SMN1) gene, and prognosis inversely correlates with the number of copies of the SMN2 gene, a human-specific homolog of...
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Mouse odorant receptor-specific glomeruli [Neuroscience]

Tue, 10/27/2015 - 12:31
In the mouse, axons of olfactory sensory neurons (OSNs) that express the same odorant receptor (OR) gene coalesce into one or a few glomeruli in the olfactory bulb. The positions of OR-specific glomeruli are traditionally described as stereotyped. Here, we have assessed quantitatively the positions of OR-specific glomeruli using serial...
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PAK3 regulates AMPAR trafficking [Neuroscience]

Tue, 10/27/2015 - 12:31
AMPA receptors (AMPARs) are the major excitatory receptors of the brain and are fundamental to synaptic plasticity, memory, and cognition. Dynamic recycling of AMPARs in neurons is regulated through several types of posttranslational modification, including phosphorylation. Here, we identify a previously unidentified signal transduction cascade that modulates phosphorylation of serine...
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