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Preview: PNAS - RSS feed of Early Edition articles

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Proceedings of the National Academy of Sciences RSS feed -- Early Edition



 



Future urban land expansion and implications for global croplands [Sustainability Science]

2016-12-27T09:51:19-08:00

Urban expansion often occurs on croplands. However, there is little scientific understanding of how global patterns of future urban expansion will affect the world’s cultivated areas. Here, we combine spatially explicit projections of urban expansion with datasets on global croplands and crop yields. Our results show that urban expansion will...



Global urban signatures of phenotypic change in animal and plant populations [Sustainability Science]

2017-01-03T08:47:11-08:00

Humans challenge the phenotypic, genetic, and cultural makeup of species by affecting the fitness landscapes on which they evolve. Recent studies show that cities might play a major role in contemporary evolution by accelerating phenotypic changes in wildlife, including animals, plants, fungi, and other organisms. Many studies of ecoevolutionary change...



Urban sustainability in an age of enduring inequalities: Advancing theory and ecometrics for the 21st-century city [Perspectives]

2017-01-06T12:50:12-08:00

The environmental fragility of cities under advanced urbanization has motivated extensive efforts to promote the sustainability of urban ecosystems and physical infrastructures. Less attention has been devoted to neighborhood inequalities and fissures in the civic infrastructure that potentially challenge social sustainability and the capacity of cities to collectively address environmental...



Global scenarios of urban density and its impacts on building energy use through 2050 [Sustainability Science]

2017-01-09T12:10:28-08:00

Although the scale of impending urbanization is well-acknowledged, we have a limited understanding of how urban forms will change and what their impact will be on building energy use. Using both top-down and bottom-up approaches and scenarios, we examine building energy use for heating and cooling. Globally, the energy use...



EHD2 restrains dynamics of caveolae by an ATP-dependent, membrane-bound, open conformation [Biochemistry]

2017-02-21T10:14:29-08:00

The EH-domain–containing protein 2 (EHD2) is a dynamin-related ATPase that confines caveolae to the cell surface by restricting the scission and subsequent endocytosis of these membrane pits. For this, EHD2 is thought to first bind to the membrane, then to oligomerize, and finally to detach, in a stringently regulated mechanistic...



Structural insights into the activation mechanism of dynamin-like EHD ATPases [Biophysics and Computational Biology]

2017-02-22T11:34:28-08:00

Eps15 (epidermal growth factor receptor pathway substrate 15)-homology domain containing proteins (EHDs) comprise a family of dynamin-related mechano-chemical ATPases involved in cellular membrane trafficking. Previous studies have revealed the structure of the EHD2 dimer, but the molecular mechanisms of membrane recruitment and assembly have remained obscure. Here, we determined the...



Reply to Shanks and Brundage: Many plausible mechanisms of pandemic mortality disparities [Letters (Online Only)]

2017-04-06T12:29:12-07:00

In our recently published paper (1), we find evidence that several metrics of socioeconomic status were associated with influenza and pneumonia mortality during the 1918 pandemic. We agree with Shanks and Brundage (2) that there are many possible causal mechanisms behind this association and appreciate the hypotheses that they add...



Variable mortality during the 1918 influenza pandemic in Chicago [Letters (Online Only)]

2017-04-06T13:44:09-07:00

In their study of influenza mortality in Chicago in 1918, Grantz et al. (1) conclude that pandemic-related mortality was related to “neighborhood level social factors” (e.g., illiteracy, homeownership, unemployment). Because “social factors” do not directly cause influenza illness or mortality, they must be surrogates for other factors. Other studies of...



Social interactions among grazing reef fish drive material flux in a coral reef ecosystem [Ecology]

2017-04-10T13:06:50-07:00

In human financial and social systems, exchanges of information among individuals cause speculative bubbles, behavioral cascades, and other correlated actions that profoundly influence system-level function. Exchanges of information are also widespread in ecological systems, but their effects on ecosystem-level processes are largely unknown. Herbivory is a critical ecological process in...



Structural hierarchy controlling dimerization and target DNA recognition in the AHR transcriptional complex [Biochemistry]

2017-04-10T13:06:52-07:00

The aryl hydrocarbon receptor (AHR) belongs to the PAS (PER-ARNT-SIM) family transcription factors and mediates broad responses to numerous environmental pollutants and cellular metabolites, modulating diverse biological processes from adaptive metabolism, acute toxicity, to normal physiology of vascular and immune systems. The AHR forms a transcriptionally active heterodimer with ARNT...



Spinal motor neuron protein supersaturation patterns are associated with inclusion body formation in ALS [Biochemistry]

2017-04-10T13:06:52-07:00

Amyotrophic lateral sclerosis (ALS) is a heterogeneous degenerative motor neuron disease linked to numerous genetic mutations in apparently unrelated proteins. These proteins, including SOD1, TDP-43, and FUS, are highly aggregation-prone and form a variety of intracellular inclusion bodies that are characteristic of different neuropathological subtypes of the disease. Contained within...



Unusual active site location and catalytic apparatus in a glycoside hydrolase family [Biochemistry]

2017-04-10T13:06:41-07:00

The human gut microbiota use complex carbohydrates as major nutrients. The requirement for an efficient glycan degrading systems exerts a major selection pressure on this microbial community. Thus, we propose that these bacteria represent a substantial resource for discovering novel carbohydrate active enzymes. To test this hypothesis, we focused on...



Immunochemical engineering of cell surfaces to generate virus resistance [Applied Biological Sciences]

2017-04-10T13:06:41-07:00

Modern immunochemical engineering allows the creation of cells that either secrete antibodies or incorporate them into various cellular compartments, including the plasma membrane. Because the receptors for most viruses are known, if one can achieve the proper stoichiometry and geometry, plasma membrane-associated antibodies to these receptors should block viral infection....



ACOX2 deficiency in primary malignant cardiac tumors [Letters (Online Only)]

2017-04-11T09:30:12-07:00

ACOX2 (acyl-CoA oxidase 2) is a peroxisomal enzyme that plays a key role in the metabolism of bile acid intermediates and the oxidation of branched-chain fatty acids. A recent PNAS paper by Vilarinho et al. (1) on ACOX2 deficiency in an 8-y-old male with elevated transaminase levels identifies a homozygous...



Community trust reduces myopic decisions of low-income individuals [Psychological and Cognitive Sciences]

2017-04-11T09:30:15-07:00

Why do the poor make shortsighted choices in decisions that involve delayed payoffs? Foregoing immediate rewards for larger, later rewards requires that decision makers (i) believe future payoffs will occur and (ii) are not forced to take the immediate reward out of financial need. Low-income individuals may be both less...



High-throughput, low-loss, low-cost, and label-free cell separation using electrophysiology-activated cell enrichment [Applied Biological Sciences]

2017-04-13T11:12:49-07:00

Currently, cell separation occurs almost exclusively by density gradient methods and by fluorescence- and magnetic-activated cell sorting (FACS/MACS). These variously suffer from lack of specificity, high cell loss, use of labels, and high capital/operating cost. We present a dielectrophoresis (DEP)-based cell-separation method, using 3D electrodes on a low-cost disposable chip;...



Can processing demands explain toddlers’ performance in false-belief tasks? [Letters (Online Only)]

2017-04-17T12:55:59-07:00

Two-and-a-half-year-olds normally fail standard false-belief tasks. In the classic version, children have to say where a protagonist will look for an apple that, unbeknownst to her, was moved to a new location. Children under 4 generally predict that the protagonist will look for her apple in its current location, rather...



Reconstructed ancestral enzymes suggest long-term cooling of Earth’s photic zone since the Archean [Evolution]

2017-04-17T11:49:09-07:00

Paleotemperatures inferred from the isotopic compositions (δ18O and δ30Si) of marine cherts suggest that Earth’s oceans cooled from 70 ± 15 °C in the Archean to the present ∼15 °C. This interpretation, however, has been subject to question due to uncertainties regarding oceanic isotopic compositions, diagenetic or metamorphic resetting of...



Economic inequality increases risk taking [Psychological and Cognitive Sciences]

2017-04-17T11:49:09-07:00

Rising income inequality is a global trend. Increased income inequality has been associated with higher rates of crime, greater consumer debt, and poorer health outcomes. The mechanisms linking inequality to poor outcomes among individuals are poorly understood. This research tested a behavioral account linking inequality to individual decision making. In...



Effect of cholesterol on the molecular structure and transitions in a clinical-grade lung surfactant extract [Chemistry]

2017-04-17T11:49:10-07:00

The lipid–protein film covering the interface of the lung alveolar in mammals is vital for proper lung function and its deficiency is related to a range of diseases. Here we present a molecular-level characterization of a clinical-grade porcine lung surfactant extract using a multitechnique approach consisting of H1–C13 solid-state nuclear...



Deubiquitinase YOD1 potentiates YAP/TAZ activities through enhancing ITCH stability [Cell Biology]

2017-04-17T11:49:10-07:00

Hippo signaling controls the expression of genes regulating cell proliferation and survival and organ size. The regulation of core components in the Hippo pathway by phosphorylation has been extensively investigated, but the roles of ubiquitination−deubiquitination processes are largely unknown. To identify deubiquitinase(s) that regulates Hippo signaling, we performed unbiased siRNA...



Redefining the essential trafficking pathway for outer membrane lipoproteins [Microbiology]

2017-04-17T11:49:11-07:00

The outer membrane (OM) of Gram-negative bacteria is a permeability barrier and an intrinsic antibiotic resistance factor. Lipoproteins are OM components that function in cell wall synthesis, diverse secretion systems, and antibiotic efflux pumps. Moreover, each of the essential OM machines that assemble the barrier requires one or more lipoproteins....



Single-cell analysis of HIV-1 transcriptional activity reveals expression of proviruses in expanded clones during ART [Microbiology]

2017-04-17T11:49:11-07:00

Little is known about the fraction of human immunodeficiency virus type 1 (HIV-1) proviruses that express unspliced viral RNA in vivo or about the levels of HIV RNA expression within single infected cells. We developed a sensitive cell-associated HIV RNA and DNA single-genome sequencing (CARD-SGS) method to investigate fractional proviral...



Adapt to more wildfire in western North American forests as climate changes [Perspectives]

2017-04-17T11:49:11-07:00

Wildfires across western North America have increased in number and size over the past three decades, and this trend will continue in response to further warming. As a consequence, the wildland–urban interface is projected to experience substantially higher risk of climate-driven fires in the coming decades. Although many plants, animals,...



Bistable metamaterial for switching and cascading elastic vibrations [Applied Physical Sciences]

2017-04-17T11:49:11-07:00

The realization of acoustic devices analogous to electronic systems, like diodes, transistors, and logic elements, suggests the potential use of elastic vibrations (i.e., phonons) in information processing, for example, in advanced computational systems, smart actuators, and programmable materials. Previous experimental realizations of acoustic diodes and mechanical switches have used nonlinearities...



Three-dimensional stable lithium metal anode with nanoscale lithium islands embedded in ionically conductive solid matrix [Chemistry]

2017-04-17T11:49:12-07:00

Rechargeable batteries based on lithium (Li) metal chemistry are attractive for next-generation electrochemical energy storage. Nevertheless, excessive dendrite growth, infinite relative dimension change, severe side reactions, and limited power output severely impede their practical applications. Although exciting progress has been made to solve parts of the above issues, a versatile...



Hippo pathway mediates resistance to cytotoxic drugs [Pharmacology]

2017-04-17T11:49:12-07:00

Chemotherapy is widely used for cancer treatment, but its effectiveness is limited by drug resistance. Here, we report a mechanism by which cell density activates the Hippo pathway, which in turn inactivates YAP, leading to changes in the regulation of genes that control the intracellular concentrations of gemcitabine and several...



Drebrin restricts rotavirus entry by inhibiting dynamin-mediated endocytosis [Microbiology]

2017-04-17T11:49:12-07:00

Despite the wide administration of several effective vaccines, rotavirus (RV) remains the single most important etiological agent of severe diarrhea in infants and young children worldwide, with an annual mortality of over 200,000 people. RV attachment and internalization into target cells is mediated by its outer capsid protein VP4. To...



Autonomous sweat extraction and analysis applied to cystic fibrosis and glucose monitoring using a fully integrated wearable platform [Physiology]

2017-04-17T11:49:13-07:00

Perspiration-based wearable biosensors facilitate continuous monitoring of individuals’ health states with real-time and molecular-level insight. The inherent inaccessibility of sweat in sedentary individuals in large volume (≥10 µL) for on-demand and in situ analysis has limited our ability to capitalize on this noninvasive and rich source of information. A wearable...



Coding of navigational affordances in the human visual system [Neuroscience]

2017-04-17T11:49:13-07:00

A central component of spatial navigation is determining where one can and cannot go in the immediate environment. We used fMRI to test the hypothesis that the human visual system solves this problem by automatically identifying the navigational affordances of the local scene. Multivoxel pattern analyses showed that a scene-selective...



Alterations in cellular metabolism triggered by URA7 or GLN3 inactivation cause imbalanced dNTP pools and increased mutagenesis [Genetics]

2017-04-17T11:49:13-07:00

Eukaryotic DNA replication fidelity relies on the concerted action of DNA polymerase nucleotide selectivity, proofreading activity, and DNA mismatch repair (MMR). Nucleotide selectivity and proofreading are affected by the balance and concentration of deoxyribonucleotide (dNTP) pools, which are strictly regulated by ribonucleotide reductase (RNR). Mutations preventing DNA polymerase proofreading activity...



Case for the genetic code as a triplet of triplets [Genetics]

2017-04-17T11:49:14-07:00

The efficiency of codon translation in vivo is controlled by many factors, including codon context. At a site early in the Salmonella flgM gene, the effects on translation of replacing codons Thr6 and Pro8 of flgM with synonymous alternates produced a 600-fold range in FlgM activity. Synonymous changes at Thr6...



Bisulfite-converted duplexes for the strand-specific detection and quantification of rare mutations [Genetics]

2017-04-17T11:49:14-07:00

The identification of mutations that are present at low frequencies in clinical samples is an essential component of precision medicine. The development of molecular barcoding for next-generation sequencing has greatly enhanced the sensitivity of detecting such mutations by massively parallel sequencing. However, further improvements in specificity would be useful for...



Inducing protein aggregation by extensional flow [Engineering]

2017-04-17T11:49:14-07:00

Relative to other extrinsic factors, the effects of hydrodynamic flow fields on protein stability and conformation remain poorly understood. Flow-induced protein remodeling and/or aggregation is observed both in Nature and during the large-scale industrial manufacture of proteins. Despite its ubiquity, the relationships between the type and magnitude of hydrodynamic flow,...



Integrin extension enables ultrasensitive regulation by cytoskeletal force [Cell Biology]

2017-04-17T11:49:14-07:00

Integrins undergo large-scale conformational changes upon activation. Signaling events driving integrin activation have previously been discussed conceptually, but not quantitatively. Here, recent measurements of the intrinsic ligand-binding affinity and free energy of each integrin conformational state on the cell surface, together with the length scales of conformational change, are used...



Dissociation of Per1 and Bmal1 circadian rhythms in the suprachiasmatic nucleus in parallel with behavioral outputs [Neuroscience]

2017-04-17T11:49:15-07:00

The temporal order of physiology and behavior in mammals is primarily regulated by the circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). Taking advantage of bioluminescence reporters, we monitored the circadian rhythms of the expression of clock genes Per1 and Bmal1 in the SCN of freely moving mice and...



Structural toggle in the RNaseH domain of Prp8 helps balance splicing fidelity and catalytic efficiency [Genetics]

2017-04-17T11:49:15-07:00

Pre-mRNA splicing is an essential step of eukaryotic gene expression that requires both high efficiency and high fidelity. Prp8 has long been considered the “master regulator” of the spliceosome, the molecular machine that executes pre-mRNA splicing. Cross-linking and structural studies place the RNaseH domain (RH) of Prp8 near the spliceosome’s...



Reply to Rubio-Fernandez et al.: Different traditional false-belief tasks impose different processing demands for toddlers [Letters (Online Only)]

2017-04-17T12:48:15-07:00

Setoh, Scott, and Baillargeon (1) propose that children may fail a false-belief task for one of two reasons: They may lack sufficient skill at one or more of the processes involved in the task, or they may be capable of executing each individual process but lack sufficient information-processing resources to...



Sensorimotor-independent development of hands and tools selectivity in the visual cortex [Psychological and Cognitive Sciences]

2017-04-17T11:49:04-07:00

The visual occipito-temporal cortex is composed of several distinct regions specialized in the identification of different object kinds such as tools and bodies. Its organization appears to reflect not only the visual characteristics of the inputs but also the behavior that can be achieved with them. For example, there are...



Using microsecond single-molecule FRET to determine the assembly pathways of T4 ssDNA binding protein onto model DNA replication forks [Biophysics and Computational Biology]

2017-04-17T11:49:04-07:00

DNA replication is a core biological process that occurs in prokaryotic cells at high speeds (∼1 nucleotide residue added per millisecond) and with high fidelity (fewer than one misincorporation event per 107 nucleotide additions). The ssDNA binding protein [gene product 32 (gp32)] of the T4 bacteriophage is a central integrating...



Correction for Mann, Core Concept: Unraveling the enigma of fast radio bursts [Corrections]

2017-04-17T11:49:04-07:00

CORE CONCEPTS Correction for “Core Concept: Unraveling the enigma of fast radio bursts,” by Adam Mann, which appeared in issue 13, March 28, 2017, of Proc Natl Acad Sci USA (114:3269–3271; 10.1073/pnas.1703512114). Victoria Kaspi was incorrectly identified as the principal investigator of the Canadian Hydrogen Intensity Mapping Experiment. Kaspi should...



Computational modeling of epiphany learning [Psychological and Cognitive Sciences]

2017-04-17T11:49:04-07:00

Models of reinforcement learning (RL) are prevalent in the decision-making literature, but not all behavior seems to conform to the gradual convergence that is a central feature of RL. In some cases learning seems to happen all at once. Limited prior research on these “epiphanies” has shown evidence of sudden...



Structure and mechanics of aegagropilae fiber network [Applied Physical Sciences]

2017-04-17T11:49:05-07:00

Fiber networks encompass a wide range of natural and manmade materials. The threads or filaments from which they are formed span a wide range of length scales: from nanometers, as in biological tissues and bundles of carbon nanotubes, to millimeters, as in paper and insulation materials. The mechanical and thermal...



Discovery of chemoautotrophic symbiosis in the giant shipworm Kuphus polythalamia (Bivalvia: Teredinidae) extends wooden-steps theory [Microbiology]

2017-04-17T11:49:05-07:00

The “wooden-steps” hypothesis [Distel DL, et al. (2000) Nature 403:725–726] proposed that large chemosynthetic mussels found at deep-sea hydrothermal vents descend from much smaller species associated with sunken wood and other organic deposits, and that the endosymbionts of these progenitors made use of hydrogen sulfide from biogenic sources (e.g., decaying...



SNAT7 is the primary lysosomal glutamine exporter required for extracellular protein-dependent growth of cancer cells [Biochemistry]

2017-04-17T11:49:05-07:00

Lysosomes degrade cellular components sequestered by autophagy or extracellular material internalized by endocytosis and phagocytosis. The macromolecule building blocks released by lysosomal hydrolysis are then exported to the cytosol by lysosomal transporters, which remain undercharacterized. In this study, we designed an in situ assay of lysosomal amino acid export based...



NGF-TrkA signaling in sensory nerves is required for skeletal adaptation to mechanical loads in mice [Medical Sciences]

2017-04-17T11:49:05-07:00

Sensory nerves emanating from the dorsal root extensively innervate the surfaces of mammalian bone, a privileged location for the regulation of biomechanical signaling. Here, we show that NGF-TrkA signaling in skeletal sensory nerves is an early response to mechanical loading of bone and is required to achieve maximal load-induced bone...



Structural and functional innovations in the real-time evolution of new ({beta}{alpha})8 barrel enzymes [Evolution]

2017-04-17T11:49:06-07:00

New genes can arise by duplication and divergence, but there is a fundamental gap in our understanding of the relationship between these genes, the evolving proteins they encode, and the fitness of the organism. Here we used crystallography, NMR dynamics, kinetics, and mass spectrometry to explain the molecular innovations that...



Knockout of the LRRC26 subunit reveals a primary role of LRRC26-containing BK channels in secretory epithelial cells [Physiology]

2017-04-17T11:49:06-07:00

Leucine-rich-repeat-containing protein 26 (LRRC26) is the regulatory γ1 subunit of Ca2+- and voltage-dependent BK-type K+ channels. BK channels that contain LRRC26 subunits are active near normal resting potentials even without Ca2+, suggesting they play unique physiological roles, likely limited to very specific cell types and cellular functions. By using Lrrc26...



Contractile and chiral activities codetermine the helicity of swimming droplet trajectories [Physics]

2017-04-17T11:49:06-07:00

Active fluids are a class of nonequilibrium systems where energy is injected into the system continuously by the constituent particles themselves. Many examples, such as bacterial suspensions and actomyosin networks, are intrinsically chiral at a local scale, so that their activity involves torque dipoles alongside the force dipoles usually considered....



Neurophysiological dynamics of phrase-structure building during sentence processing [Neuroscience]

2017-04-17T11:49:07-07:00

Although sentences unfold sequentially, one word at a time, most linguistic theories propose that their underlying syntactic structure involves a tree of nested phrases rather than a linear sequence of words. Whether and how the brain builds such structures, however, remains largely unknown. Here, we used human intracranial recordings and...



Immunomodulation-accelerated neuronal regeneration following selective rod photoreceptor cell ablation in the zebrafish retina [Neuroscience]

2017-04-17T11:49:07-07:00

Müller glia (MG) function as inducible retinal stem cells in zebrafish, completely repairing the eye after damage. The innate immune system has recently been shown to promote tissue regeneration in which classic wound-healing responses predominate. However, regulatory roles for leukocytes during cellular regeneration—i.e., selective cell-loss paradigms akin to degenerative disease—are...



Insect haptoelectrical stimulation of Venus flytrap triggers exocytosis in gland cells [Plant Biology]

2017-04-17T11:49:07-07:00

The Venus flytrap Dionaea muscipula captures insects and consumes their flesh. Prey contacting touch-sensitive hairs trigger traveling electrical waves. These action potentials (APs) cause rapid closure of the trap and activate secretory functions of glands, which cover its inner surface. Such prey-induced haptoelectric stimulation activates the touch hormone jasmonate (JA)...



Peter C. Nowell (1928-2016) [Retrospectives]

2017-04-17T11:49:07-07:00

The pioneering cancer cytogeneticist, Peter C. Nowell, died on December 26, 2016, from complications of Alzheimer’s disease at the age of 88. His work laid the foundation for the recognition of the genetic basis of cancer that paved the way for modern targeted cancer therapeutics. Nowell’s observations of changes in...



Zeaxanthin-dependent nonphotochemical quenching does not occur in photosystem I in the higher plant Arabidopsis thaliana [Plant Biology]

2017-04-17T11:49:08-07:00

Nonphotochemical quenching (NPQ) is the process that protects the photosynthetic apparatus of plants and algae from photodamage by dissipating as heat the energy absorbed in excess. Studies on NPQ have almost exclusively focused on photosystem II (PSII), as it was believed that NPQ does not occur in photosystem I (PSI)....



Small molecule-mediated inhibition of myofibroblast transdifferentiation for the treatment of fibrosis [Cell Biology]

2017-04-17T11:49:08-07:00

Fibrosis, a disease in which excessive amounts of connective tissue accumulate in response to physical damage and/or inflammatory insult, affects nearly every tissue in the body and can progress to a state of organ malfunction and death. A hallmark of fibrotic disease is the excessive accumulation of extracellular matrix-secreting activated...



Selective in vivo removal of pathogenic anti-MAG autoantibodies, an antigen-specific treatment option for anti-MAG neuropathy [Neuroscience]

2017-04-17T11:49:08-07:00

Anti-MAG (myelin-associated glycoprotein) neuropathy is a disabling autoimmune peripheral neuropathy caused by monoclonal IgM autoantibodies that recognize the carbohydrate epitope HNK-1 (human natural killer-1). This glycoepitope is highly expressed on adhesion molecules, such as MAG, present in myelinated nerve fibers. Because the pathogenicity and demyelinating properties of anti-MAG autoantibodies are...



IP3-mediated gating mechanism of the IP3 receptor revealed by mutagenesis and X-ray crystallography [Biochemistry]

2017-04-17T11:49:08-07:00

The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) is an IP3-gated ion channel that releases calcium ions (Ca2+) from the endoplasmic reticulum. The IP3-binding sites in the large cytosolic domain are distant from the Ca2+ conducting pore, and the allosteric mechanism of how IP3 opens the Ca2+ channel remains elusive. Here, we...



Intensifying postfire weather and biological invasion drive species loss in a Mediterranean-type biodiversity hotspot [Environmental Sciences]

2017-04-17T11:49:08-07:00

Prolonged periods of extreme heat or drought in the first year after fire affect the resilience and diversity of fire-dependent ecosystems by inhibiting seed germination or increasing mortality of seedlings and resprouting individuals. This interaction between weather and fire is of growing concern as climate changes, particularly in systems subject...



Defective synaptic connectivity and axonal neuropathology in a human iPSC-based model of familial Parkinson’s disease [Neuroscience]

2017-04-17T11:49:09-07:00

α-Synuclein (αSyn) is the major gene linked to sporadic Parkinson’s disease (PD), whereas the G209A (p.A53T) αSyn mutation causes a familial form of PD characterized by early onset and a generally severe phenotype, including nonmotor manifestations. Here we generated de novo induced pluripotent stem cells (iPSCs) from patients harboring the...



Massive horizontal transfer of transposable elements in insects [Evolution]

2017-04-17T11:49:09-07:00

Horizontal transfer (HT) of genetic material is central to the architecture and evolution of prokaryote genomes. Within eukaryotes, the majority of HTs reported so far are transfers of transposable elements (TEs). These reports essentially come from studies focusing on specific lineages or types of TEs. Because of the lack of...



Memory-n strategies of direct reciprocity [Social Sciences]

2017-04-18T08:57:58-07:00

Humans routinely use conditionally cooperative strategies when interacting in repeated social dilemmas. They are more likely to cooperate if others cooperated before, and are ready to retaliate if others defected. To capture the emergence of reciprocity, most previous models consider subjects who can only choose from a restricted set of...



Activation of NLRP3 inflammasome complex potentiates venous thrombosis in response to hypoxia [Medical Sciences]

2017-04-18T08:57:59-07:00

Venous thromboembolism (VTE), caused by altered hemostasis, remains the third most common cause of mortality among all cardiovascular conditions. In addition to established genetic and acquired risk factors, low-oxygen environments also predispose otherwise healthy individuals to VTE. Although disease etiology appears to entail perturbation of hemostasis pathways, the key molecular...



Reconstructing the spectrotemporal modulations of real-life sounds from fMRI response patterns [Neuroscience]

2017-04-18T08:57:59-07:00

Ethological views of brain functioning suggest that sound representations and computations in the auditory neural system are optimized finely to process and discriminate behaviorally relevant acoustic features and sounds (e.g., spectrotemporal modulations in the songs of zebra finches). Here, we show that modeling of neural sound representations in terms of...



Structural and stereoelectronic insights into oxygenase-catalyzed formation of ethylene from 2-oxoglutarate [Biochemistry]

2017-04-18T08:57:59-07:00

Ethylene is important in industry and biological signaling. In plants, ethylene is produced by oxidation of 1-aminocyclopropane-1-carboxylic acid, as catalyzed by 1-aminocyclopropane-1-carboxylic acid oxidase. Bacteria catalyze ethylene production, but via the four-electron oxidation of 2-oxoglutarate to give ethylene in an arginine-dependent reaction. Crystallographic and biochemical studies on the Pseudomonas syringae...



Honeybee gut microbiota promotes host weight gain via bacterial metabolism and hormonal signaling [Microbiology]

2017-04-18T08:58:00-07:00

Social bees harbor a simple and specialized microbiota that is spatially organized into different gut compartments. Recent results on the potential involvement of bee gut communities in pathogen protection and nutritional function have drawn attention to the impact of the microbiota on bee health. However, the contributions of gut microbiota...



Adult enteric nervous system in health is maintained by a dynamic balance between neuronal apoptosis and neurogenesis [Neuroscience]

2017-04-18T08:58:01-07:00

According to current dogma, there is little or no ongoing neurogenesis in the fully developed adult enteric nervous system. This lack of neurogenesis leaves unanswered the question of how enteric neuronal populations are maintained in adult guts, given previous reports of ongoing neuronal death. Here, we confirm that despite ongoing...



Morality constrains the default representation of what is possible [Psychological and Cognitive Sciences]

2017-04-18T08:58:01-07:00

The capacity for representing and reasoning over sets of possibilities, or modal cognition, supports diverse kinds of high-level judgments: causal reasoning, moral judgment, language comprehension, and more. Prior research on modal cognition asks how humans explicitly and deliberatively reason about what is possible but has not investigated whether or how...



Regulating plant physiology with organic electronics [Plant Biology]

2017-04-18T08:58:01-07:00

The organic electronic ion pump (OEIP) provides flow-free and accurate delivery of small signaling compounds at high spatiotemporal resolution. To date, the application of OEIPs has been limited to delivery of nonaromatic molecules to mammalian systems, particularly for neuroscience applications. However, many long-standing questions in plant biology remain unanswered due...



Structural features and lipid binding domain of tubulin on biomimetic mitochondrial membranes [Biophysics and Computational Biology]

2017-04-18T08:58:02-07:00

Dimeric tubulin, an abundant water-soluble cytosolic protein known primarily for its role in the cytoskeleton, is routinely found to be associated with mitochondrial outer membranes, although the structure and physiological role of mitochondria-bound tubulin are still unknown. There is also no consensus on whether tubulin is a peripheral membrane protein...



Role of atmospheric oxidation in recent methane growth [Environmental Sciences]

2017-04-17T11:49:10-07:00

The growth in global methane (CH4) concentration, which had been ongoing since the industrial revolution, stalled around the year 2000 before resuming globally in 2007. We evaluate the role of the hydroxyl radical (OH), the major CH4 sink, in the recent CH4 growth. We also examine the influence of systematic...



Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl [Environmental Sciences]

2017-04-19T12:45:36-07:00

Methane is the second strongest anthropogenic greenhouse gas and its atmospheric burden has more than doubled since 1850. Methane concentrations stabilized in the early 2000s and began increasing again in 2007. Neither the stabilization nor the recent growth are well understood, as evidenced by multiple competing hypotheses in recent literature....



Lignocellulose pretreatment in a fungus-cultivating termite [Environmental Sciences]

2017-04-19T12:45:36-07:00

Depolymerizing lignin, the complex phenolic polymer fortifying plant cell walls, is an essential but challenging starting point for the lignocellulosics industries. The variety of ether– and carbon–carbon interunit linkages produced via radical coupling during lignification limit chemical and biological depolymerization efficiency. In an ancient fungus-cultivating termite system, we reveal unprecedentedly...



Unifying mechanism for different fibrotic diseases [Medical Sciences]

2017-04-19T12:45:36-07:00

Fibrotic diseases are not well-understood. They represent a number of different diseases that are characterized by the development of severe organ fibrosis without any obvious cause, such as the devastating diseases idiopathic pulmonary fibrosis (IPF) and scleroderma. These diseases have a poor prognosis comparable with endstage cancer and are uncurable....



Nuclear Shp2 directs normal embryo implantation via facilitating the ER{alpha} tyrosine phosphorylation by the Src kinase [Physiology]

2017-04-19T12:45:36-07:00

Estrogen and progesterone coupled with locally produced signaling molecules are essential for embryo implantation. However, the hierarchical landscape of the molecular pathways that governs this process remains largely unexplored. Here we show that the protein tyrosine phosphatase Shp2, a positive transducer of RTK signaling, is predominately localized in the nuclei...



Modeling language shift [Commentaries]

2017-04-20T13:09:30-07:00

It is estimated that there are as many as 6,000 distinct languages currently spoken, but this cultural diversity is rapidly disappearing. In terms of the fraction of the total being lost, the estimated current rate of language extinction exceeds the rate of loss of biodiversity (1–3). Small geographical ranges and...



Ctf4-related protein recruits LHP1-PRC2 to maintain H3K27me3 levels in dividing cells in Arabidopsis thaliana [Plant Biology]

2017-04-20T13:09:30-07:00

Polycomb Repressive Complex (PRC) 2 catalyzes the H3K27me3 modification that warrants inheritance of a repressive chromatin structure during cell division, thereby assuring stable target gene repression in differentiated cells. It is still under investigation how H3K27me3 is passed on from maternal to filial strands during DNA replication; however, cell division...



Lysibodies are IgG Fc fusions with lysin binding domains targeting Staphylococcus aureus wall carbohydrates for effective phagocytosis [Microbiology]

2017-04-20T13:09:31-07:00

The cell wall of Gram-positive bacteria contains abundant surface-exposed carbohydrate molecules that are highly conserved within and often across species. The potential therapeutic usefulness of high-affinity antibodies to cell wall carbohydrates is unquestioned, however obtaining such antibodies is challenging due to the poor overall immunogenicity of these bacterial targets. Autolysins...



Toward a direct and scalable identification of reduced models for categorical processes [Biophysics and Computational Biology]

2017-04-21T12:45:12-07:00

The applicability of many computational approaches is dwelling on the identification of reduced models defined on a small set of collective variables (colvars). A methodology for scalable probability-preserving identification of reduced models and colvars directly from the data is derived—not relying on the availability of the full relation matrices at...



Differentiation of V2a interneurons from human pluripotent stem cells [Cell Biology]

2017-04-24T11:56:05-07:00

The spinal cord consists of multiple neuronal cell types that are critical to motor control and arise from distinct progenitor domains in the developing neural tube. Excitatory V2a interneurons in particular are an integral component of central pattern generators that control respiration and locomotion; however, the lack of a robust...



Microglial NF{kappa}B-TNF{alpha} hyperactivation induces obsessive-compulsive behavior in mouse models of progranulin-deficient frontotemporal dementia [Neuroscience]

2017-04-24T11:56:05-07:00

Frontotemporal dementia (FTD) is the second most common dementia before 65 years of age. Haploinsufficiency in the progranulin (GRN) gene accounts for 10% of all cases of familial FTD. GRN mutation carriers have an increased risk of autoimmune disorders, accompanied by elevated levels of tissue necrosis factor (TNF) α. We...



Air quality, health, and climate implications of China’s synthetic natural gas development [Sustainability Sciences]

2017-04-24T11:56:06-07:00

Facing severe air pollution and growing dependence on natural gas imports, the Chinese government plans to increase coal-based synthetic natural gas (SNG) production. Although displacement of coal with SNG benefits air quality, it increases CO2 emissions. Due to variations in air pollutant and CO2 emission factors and energy efficiencies across...



Latently and uninfected healthcare workers exposed to TB make protective antibodies against Mycobacterium tuberculosis [Microbiology]

2017-04-24T11:56:06-07:00

The role of Igs in natural protection against infection by Mycobacterium tuberculosis (Mtb), the causative agent of TB, is controversial. Although passive immunization with mAbs generated against mycobacterial antigens has shown protective efficacy in murine models of infection, studies in B cell-depleted animals only showed modest phenotypes. We do not...



csiLSFM combines light-sheet fluorescence microscopy and coherent structured illumination for a lateral resolution below 100 nm [Applied Physical Sciences]

2017-04-24T11:56:06-07:00

Light-sheet-based fluorescence microscopy (LSFM) features optical sectioning in the excitation process. It minimizes fluorophore bleaching as well as phototoxic effects and provides a true axial resolution. The detection path resembles properties of conventional fluorescence microscopy. Structured illumination microscopy (SIM) is attractive for superresolution because of its moderate excitation intensity, high...



Morphotype of bacteroids in different legumes correlates with the number and type of symbiotic NCR peptides [Plant Biology]

2017-04-24T11:56:07-07:00

In legume nodules, rhizobia differentiate into nitrogen-fixing forms called bacteroids, which are enclosed by a plant membrane in an organelle-like structure called the symbiosome. In the Inverted Repeat-Lacking Clade (IRLC) of legumes, this differentiation is terminal due to irreversible loss of cell division ability and is associated with genome amplification...



Nucleophilic water attack is not a possible mechanism for O-O bond formation in photosystem II [Biophysics and Computational Biology]

2017-04-24T11:56:07-07:00

Two different types of mechanisms are at present suggested for the O–O bond-formation step in photosystem II. The first one is a coupling between an oxyl radical and a bridging oxo. The second one is a nucleophilic water attack on a terminal oxo (or oxyl) group. In the present short...



Cas1 and the Csy complex are opposing regulators of Cas2/3 nuclease activity [Biochemistry]

2017-04-24T11:56:07-07:00

The type I-F CRISPR adaptive immune system in Pseudomonas aeruginosa (PA14) consists of two CRISPR loci and six CRISPR-associated (cas) genes. Type I-F systems rely on a CRISPR RNA (crRNA)-guided surveillance complex (Csy complex) to bind foreign DNA and recruit a trans-acting nuclease (i.e., Cas2/3) for target degradation. In most...



Deciphering the sugar biosynthetic pathway and tailoring steps of nucleoside antibiotic A201A unveils a GDP-l-galactose mutase [Biochemistry]

2017-04-24T11:56:07-07:00

Galactose, a monosaccharide capable of assuming two possible configurational isomers (d-/l-), can exist as a six-membered ring, galactopyranose (Galp), or as a five-membered ring, galactofuranose (Galf). UDP-galactopyranose mutase (UGM) mediates the conversion of pyranose to furanose thereby providing a precursor for d-Galf. Moreover, UGM is critical to the virulence of...



Profile of Ian A. Wilson [Profiles]

2017-04-24T11:56:07-07:00

Viewed up close, antibodies, cellular receptors, and viral proteins may look like sloppy piles of spaghetti, fettucine, and fusilli to the untrained eye, but that’s not what Ian Wilson sees. “Protein structures are things of beauty, with their complex web of intricately positioned and interlocking elements that fold up precisely...



Structure of Myo7b/USH1C complex suggests a general PDZ domain binding mode by MyTH4-FERM myosins [Biochemistry]

2017-04-24T11:56:08-07:00

Unconventional myosin 7a (Myo7a), myosin 7b (Myo7b), and myosin 15a (Myo15a) all contain MyTH4-FERM domains (myosin tail homology 4-band 4.1, ezrin, radixin, moesin; MF) in their cargo binding tails and are essential for the growth and function of microvilli and stereocilia. Numerous mutations have been identified in the MyTH4-FERM tandems...



Reading a 400,000-year record of earthquake frequency for an intraplate fault [Earth, Atmospheric, and Planetary Sciences]

2017-04-24T11:56:08-07:00

Our understanding of the frequency of large earthquakes at timescales longer than instrumental and historical records is based mostly on paleoseismic studies of fast-moving plate-boundary faults. Similar study of intraplate faults has been limited until now, because intraplate earthquake recurrence intervals are generally long (10s to 100s of thousands of...



Numerical evidence for thermally induced monopoles [Physics]

2017-04-24T11:56:08-07:00

Electric charges are conserved. The same would be expected to hold for magnetic charges, yet magnetic monopoles have never been observed. It is therefore surprising that the laws of nonequilibrium thermodynamics, combined with Maxwell’s equations, suggest that colloidal particles heated or cooled in certain polar or paramagnetic solvents may behave...



Endocannabinoid system acts as a regulator of immune homeostasis in the gut [Immunology and Inflammation]

2017-04-24T11:56:08-07:00

Endogenous cannabinoids (endocannabinoids) are small molecules biosynthesized from membrane glycerophospholipid. Anandamide (AEA) is an endogenous intestinal cannabinoid that controls appetite and energy balance by engagement of the enteric nervous system through cannabinoid receptors. Here, we uncover a role for AEA and its receptor, cannabinoid receptor 2 (CB2), in the regulation...



Quantifying the influence of global warming on unprecedented extreme climate events [Environmental Sciences]

2017-04-24T11:56:08-07:00

Efforts to understand the influence of historical global warming on individual extreme climate events have increased over the past decade. However, despite substantial progress, events that are unprecedented in the local observational record remain a persistent challenge. Leveraging observations and a large climate model ensemble, we quantify uncertainty in the...



Murine model indicates 22q11.2 signaling adaptor CRKL is a dosage-sensitive regulator of genitourinary development [Genetics]

2017-04-24T11:56:09-07:00

The spectrum of congenital anomalies affecting either the upper tract (kidneys and ureters) or lower tract (reproductive organs) of the genitourinary (GU) system are fundamentally linked by the developmental origin of multiple GU tissues, including the kidneys, gonads, and reproductive ductal systems: the intermediate mesoderm. Although ∼31% of DiGeorge/del22q11.2 syndrome...



Ocean warming since 1982 has expanded the niche of toxic algal blooms in the North Atlantic and North Pacific oceans [Ecology]

2017-04-24T11:56:09-07:00

Global ocean temperatures are rising, yet the impacts of such changes on harmful algal blooms (HABs) are not fully understood. Here we used high-resolution sea-surface temperature records (1982 to 2016) and temperature-dependent growth rates of two algae that produce potent biotoxins, Alexandrium fundyense and Dinophysis acuminata, to evaluate recent changes...



Interaction of proliferating cell nuclear antigen with PMS2 is required for MutL{alpha} activation and function in mismatch repair [Biochemistry]

2017-04-24T11:56:09-07:00

Eukaryotic MutLα (mammalian MLH1–PMS2 heterodimer; MLH1–PMS1 in yeast) functions in early steps of mismatch repair as a latent endonuclease that requires a mismatch, MutSα/β, and DNA-loaded proliferating cell nuclear antigen (PCNA) for activation. We show here that human PCNA and MutLα interact specifically but weakly in solution to form a...



Estrogen receptor {beta}, a regulator of androgen receptor signaling in the mouse ventral prostate [Medical Sciences]

2017-04-24T11:56:10-07:00

As estrogen receptor β−/− (ERβ−/−) mice age, the ventral prostate (VP) develops increased numbers of hyperplastic, fibroplastic lesions and inflammatory cells. To identify genes involved in these changes, we used RNA sequencing and immunohistochemistry to compare gene expression profiles in the VP of young (2-mo-old) and aging (18-mo-old) ERβ−/− mice...



CYCLOPS reveals human transcriptional rhythms in health and disease [Systems Biology]

2017-04-24T11:56:10-07:00

Circadian rhythms modulate many aspects of physiology. Knowledge of the molecular basis of these rhythms has exploded in the last 20 years. However, most of these data are from model organisms, and translation to clinical practice has been limited. Here, we present an approach to identify molecular rhythms in humans...



Correction for Naviaux et al., Metabolic features of chronic fatigue syndrome [Corrections]

2017-04-24T11:56:10-07:00

MEDICAL SCIENCES Correction for “Metabolic features of chronic fatigue syndrome,” by Robert K. Naviaux, Jane C. Naviaux, Kefeng Li, A. Taylor Bright, William A. Alaynick, Lin Wang, Asha Baxter, Neil Nathan, Wayne Anderson, and Eric Gordon, which appeared in issue 37, September 13, 2016, of Proc Natl Acad Sci USA...



Gestational bisphenol-A exposure lowers the threshold for autoimmunity in a model of multiple sclerosis [Immunology and Inflammation]

2017-04-24T11:56:10-07:00

Environmental and hormonal factors are implicated in dysimmunity in multiple sclerosis. We investigated whether bisphenol-A, a prominent contaminant with endocrine-disrupting capabilities, altered susceptibility in an inflammatory model of multiple sclerosis. We found that gestational, but not adult, exposure to bisphenol-A increased the development of experimental autoimmune encephalomyelitis in adulthood in...