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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



 



Solar thermochemical splitting of water to generate hydrogen [Perspectives]

2017-05-18T11:58:25-07:00

Solar photochemical means of splitting water (artificial photosynthesis) to generate hydrogen is emerging as a viable process. The solar thermochemical route also promises to be an attractive means of achieving this objective. In this paper we present different types of thermochemical cycles that one can use for the purpose. These...



Water is an active matrix of life for cell and molecular biology [Perspectives]

2017-06-07T12:43:37-07:00

Szent-Győrgi called water the “matrix of life” and claimed that there was no life without it. This statement is true, as far as we know, on our planet, but it is not clear whether it must hold throughout the cosmos. To evaluate that question requires a close consideration of the...



Microscopic dynamics of charge separation at the aqueous electrochemical interface [Chemistry]

2017-07-11T09:36:45-07:00

We have used molecular simulation and methods of importance sampling to study the thermodynamics and kinetics of ionic charge separation at a liquid water–metal interface. We have considered this process using canonical examples of two different classes of ions: a simple alkali–halide pair, Na+I−, or classical ions, and the products...



Molecular characterization of water and surfactant AOT at nanoemulsion surfaces [Chemistry]

2017-07-31T11:51:02-07:00

Nanoemulsions and microemulsions are environments where oil and water can be solubilized in one another to provide a unique platform for many different biological and industrial applications. Nanoemulsions, unlike microemulsions, have seen little work done to characterize molecular interactions at their surfaces. This study provides a detailed investigation of the...



Mechanism of ion adsorption to aqueous interfaces: Graphene/water vs. air/water [Chemistry]

2017-08-21T12:06:10-07:00

The adsorption of ions to aqueous interfaces is a phenomenon that profoundly influences vital processes in many areas of science, including biology, atmospheric chemistry, electrical energy storage, and water process engineering. Although classical electrostatics theory predicts that ions are repelled from water/hydrophobe (e.g., air/water) interfaces, both computer simulations and experiments...



Covariations in ecological scaling laws fostered by community dynamics [Ecology]

2017-08-22T08:29:30-07:00

Scaling laws in ecology, intended both as functional relationships among ecologically relevant quantities and the probability distributions that characterize their occurrence, have long attracted the interest of empiricists and theoreticians. Empirical evidence exists of power laws associated with the number of species inhabiting an ecosystem, their abundances, and traits. Although...



XFEL structures of the influenza M2 proton channel: Room temperature water networks and insights into proton conduction [Biophysics and Computational Biology]

2017-08-23T11:33:34-07:00

The M2 proton channel of influenza A is a drug target that is essential for the reproduction of the flu virus. It is also a model system for the study of selective, unidirectional proton transport across a membrane. Ordered water molecules arranged in “wires” inside the channel pore have been...



Seed dispersal increases local species richness and reduces spatial turnover of tropical tree seedlings [Ecology]

2017-08-28T11:48:05-07:00

Dispersal is thought to be a key process underlying the high spatial diversity of tropical forests. Just how important dispersal is in structuring plant communities is nevertheless an open question because it is very difficult to isolate dispersal from other processes, and thereby measure its effect. Using a unique situation,...



Direct dating of Neanderthal remains from the site of Vindija Cave and implications for the Middle to Upper Paleolithic transition [Genetics]

2017-09-05T09:11:16-07:00

Previous dating of the Vi-207 and Vi-208 Neanderthal remains from Vindija Cave (Croatia) led to the suggestion that Neanderthals survived there as recently as 28,000–29,000 B.P. Subsequent dating yielded older dates, interpreted as ages of at least ∼32,500 B.P. We have redated these same specimens using an approach based on...



Type 1 diabetes induction in humanized mice [Medical Sciences]

2017-09-05T09:11:19-07:00

There is an urgent and unmet need for humanized in vivo models of type 1 diabetes to study immunopathogenesis and immunotherapy, and in particular antigen-specific therapy. Transfer of patient blood lymphocytes to immunodeficient mice is associated with xenogeneic graft-versus-host reactivity that complicates assessment of autoimmunity. Improved models could identify which...



Single rat muscle Na+ channel mutation confers batrachotoxin autoresistance found in poison-dart frog Phyllobates terribilis [Pharmacology]

2017-09-05T09:11:20-07:00

Poison-dart Phyllobates terribilis frogs sequester lethal amounts of steroidal alkaloid batrachotoxin (BTX) in their skin as a defense mechanism against predators. BTX targets voltage-gated Na+ channels and enables them to open persistently. How BTX autoresistance arises in such frogs remains a mystery. The BTX receptor has been delineated along the...



Molecular basis of mammalian transmissibility of avian H1N1 influenza viruses and their pandemic potential [Microbiology]

2017-09-05T09:11:22-07:00

North American wild birds are an important reservoir of influenza A viruses, yet the potential of viruses in this reservoir to transmit and cause disease in mammals is not well understood. Our surveillance of avian influenza viruses (AIVs) at Delaware Bay, USA, revealed a group of similar H1N1 AIVs isolated...



Self-healing catalysis in water [Chemistry]

2017-09-05T09:11:22-07:00

Principles for designing self-healing water-splitting catalysts are presented together with a formal kinetics model to account for the key chemical steps needed for self-healing. Self-healing may be realized if the catalysts are able to self-assemble at applied potentials less than that needed for catalyst turnover. Solution pH provides a convenient...



RPE65 has an additional function as the lutein to meso-zeaxanthin isomerase in the vertebrate eye [Biochemistry]

2017-09-05T09:11:23-07:00

Carotenoids are plant-derived pigment molecules that vertebrates cannot synthesize de novo that protect the fovea of the primate retina from oxidative stress and light damage. meso-Zeaxanthin is an ocular-specific carotenoid for which there are no common dietary sources. It is one of the three major carotenoids present at the foveal...



Stability of equidimensional pseudo-single-domain magnetite over billion-year timescales [Earth, Atmospheric, and Planetary Sciences]

2017-09-05T09:11:25-07:00

Interpretations of paleomagnetic observations assume that naturally occurring magnetic particles can retain their primary magnetic recording over billions of years. The ability to retain a magnetic recording is inferred from laboratory measurements, where heating causes demagnetization on the order of seconds. The theoretical basis for this inference comes from previous...



Cellular responses to human cytomegalovirus infection: Induction of a mesenchymal-to-epithelial transition (MET) phenotype [Microbiology]

2017-09-05T09:11:25-07:00

Human cytomegalovirus (HCMV) is the prototypical human β-herpes virus. Here we perform a systems analysis of the HCMV host-cell transcriptome, using gene set enrichment analysis (GSEA) as an engine to globally map the host–pathogen interaction across two cell types. Our analysis identified several previously unknown signatures of infection, such as...



Investigation of the mechanism of the SpnF-catalyzed [4+2]-cycloaddition reaction in the biosynthesis of spinosyn A [Chemistry]

2017-09-05T09:11:31-07:00

The Diels–Alder reaction is one of the most common methods to chemically synthesize a six-membered carbocycle. While it has long been speculated that the cyclohexene moiety found in many secondary metabolites is also introduced via similar chemistry, the enzyme SpnF involved in the biosynthesis of the insecticide spinosyn A in...



Drusen in patient-derived hiPSC-RPE models of macular dystrophies [Cell Biology]

2017-09-06T12:34:16-07:00

Age-related macular degeneration (AMD) and related macular dystrophies (MDs) are a major cause of vision loss. However, the mechanisms underlying their progression remain ill-defined. This is partly due to the lack of disease models recapitulating the human pathology. Furthermore, in vivo studies have yielded limited understanding of the role of...



Gut bacteria from multiple sclerosis patients modulate human T cells and exacerbate symptoms in mouse models [Immunology and Inflammation]

2017-09-11T11:39:40-07:00

The gut microbiota regulates T cell functions throughout the body. We hypothesized that intestinal bacteria impact the pathogenesis of multiple sclerosis (MS), an autoimmune disorder of the CNS and thus analyzed the microbiomes of 71 MS patients not undergoing treatment and 71 healthy controls. Although no major shifts in microbial...



Exposure to unpredictable maternal sensory signals influences cognitive development across species [Psychological and Cognitive Sciences]

2017-09-11T11:39:40-07:00

Maternal care is a critical determinant of child development. However, our understanding of processes and mechanisms by which maternal behavior influences the developing human brain remains limited. Animal research has illustrated that patterns of sensory information is important in shaping neural circuits during development. Here we examined the relation between...



New evidence on the impact of sustained exposure to air pollution on life expectancy from China’s Huai River Policy [Sustainability Science]

2017-09-11T11:39:41-07:00

This paper finds that a 10-μg/m3 increase in airborne particulate matter [particulate matter smaller than 10 μm (PM10)] reduces life expectancy by 0.64 years (95% confidence interval = 0.21–1.07). This estimate is derived from quasiexperimental variation in PM10 generated by China’s Huai River Policy, which provides free or heavily subsidized...



U-Th dating reveals regional-scale decline of branching Acropora corals on the Great Barrier Reef over the past century [Ecology]

2017-09-11T11:39:41-07:00

Hard coral cover on the Great Barrier Reef (GBR) is on a trajectory of decline. However, little is known about past coral mortality before the advent of long-term monitoring (circa 1980s). Using paleoecological analysis and high-precision uranium-thorium (U-Th) dating, we reveal an extensive loss of branching Acropora corals and changes...



Dysregulation of spliceosome gene expression in advanced prostate cancer by RNA-binding protein PSF [Medical Sciences]

2017-09-11T11:39:41-07:00

Developing therapeutic approaches are necessary for treating hormone-refractory prostate cancer. Activation of androgen receptor (AR) and its variants’ expression along with the downstream signals are mostly important for disease progression. However, the mechanism for marked increases of AR signals and its expression is still unclear. Here, we revealed that various...



Mechanisms for restraining cAMP-dependent protein kinase revealed by subunit quantitation and cross-linking approaches [Biochemistry]

2017-09-11T11:39:41-07:00

Protein phosphorylation by cyclic AMP-dependent protein kinase (PKA) underlies key cellular processes, including sympathetic stimulation of heart cells, and potentiation of synaptic strength in neurons. Unrestrained PKA activity is pathological, and an enduring challenge is to understand how the activity of PKA catalytic subunits is directed in cells. We developed...



Nanoswitch-linked immunosorbent assay (NLISA) for fast, sensitive, and specific protein detection [Biophysics and Computational Biology]

2017-09-11T11:39:42-07:00

Protein detection and quantification play critical roles in both basic research and clinical practice. Current detection platforms range from the widely used ELISA to more sophisticated, and more expensive, approaches such as digital ELISA. Despite advances, there remains a need for a method that combines the simplicity and cost-effectiveness of...



Coupling of pollination services and coffee suitability under climate change [Environmental Sciences]

2017-09-11T11:39:42-07:00

Climate change will cause geographic range shifts for pollinators and major crops, with global implications for food security and rural livelihoods. However, little is known about the potential for coupled impacts of climate change on pollinators and crops. Coffee production exemplifies this issue, because large losses in areas suitable for...



Atmospheric evidence for a global secular increase in carbon isotopic discrimination of land photosynthesis [Earth, Atmospheric, and Planetary Sciences]

2017-09-11T11:39:42-07:00

A decrease in the 13C/12C ratio of atmospheric CO2 has been documented by direct observations since 1978 and from ice core measurements since the industrial revolution. This decrease, known as the 13C-Suess effect, is driven primarily by the input of fossil fuel-derived CO2 but is also sensitive to land and...



Acidophilic green algal genome provides insights into adaptation to an acidic environment [Plant Biology]

2017-09-11T11:39:42-07:00

Some microalgae are adapted to extremely acidic environments in which toxic metals are present at high levels. However, little is known about how acidophilic algae evolved from their respective neutrophilic ancestors by adapting to particular acidic environments. To gain insights into this issue, we determined the draft genome sequence of...



Cryo-EM structure of the bacteriophage T4 isometric head at 3.3-A resolution and its relevance to the assembly of icosahedral viruses [Biophysics and Computational Biology]

2017-09-11T11:39:43-07:00

The 3.3-Å cryo-EM structure of the 860-Å-diameter isometric mutant bacteriophage T4 capsid has been determined. WT T4 has a prolate capsid characterized by triangulation numbers (T numbers) Tend = 13 for end caps and Tmid = 20 for midsection. A mutation in the major capsid protein, gp23, produced T=13 icosahedral...



Structures of the peptide-modifying radical SAM enzyme SuiB elucidate the basis of substrate recognition [Biochemistry]

2017-09-11T11:39:43-07:00

Posttranslational modification of ribosomally synthesized peptides provides an elegant means for the production of biologically active molecules known as RiPPs (ribosomally synthesized and posttranslationally modified peptides). Although the leader sequence of the precursor peptide is often required for turnover, the exact mode of recognition by the modifying enzymes remains unclear...



CD1d-Restricted pathways in hepatocytes control local natural killer T cell homeostasis and hepatic inflammation [Immunology and Inflammation]

2017-09-11T11:39:43-07:00

Invariant natural killer T (iNKT) cells recognize lipid antigens presented by CD1d and play a central role in regulating immunity and inflammation in peripheral tissues. However, the mechanisms which govern iNKT cell homeostasis after thymic emigration are incompletely understood. Here we demonstrate that microsomal triglyceride transfer protein (MTP), a protein...



Profile of Daniel H. Janzen [Profiles]

2017-09-11T11:39:43-07:00

When Daniel Janzen gave his acceptance speech for the 1997 Kyoto Prize, he disappointed many people who had come to hear a preeminent biologist discuss iconic studies, from ant–acacia mutualism to seed predation (1, 2). “They expected a talk about science, but I’d switched to conservation,” explains Janzen, DiMaura Professor...



Arresting dissolution by interfacial rheology design [Engineering]

2017-09-11T11:39:43-07:00

A strategy to halt dissolution of particle-coated air bubbles in water based on interfacial rheology design is presented. Whereas previously a dense monolayer was believed to be required for such an “armored bubble” to resist dissolution, in fact engineering a 2D yield stress interface suffices to achieve such performance at...



Gut microbiota from multiple sclerosis patients enables spontaneous autoimmune encephalomyelitis in mice [Immunology and Inflammation]

2017-09-11T11:39:43-07:00

There is emerging evidence that the commensal microbiota has a role in the pathogenesis of multiple sclerosis (MS), a putative autoimmune disease of the CNS. Here, we compared the gut microbial composition of 34 monozygotic twin pairs discordant for MS. While there were no major differences in the overall microbial...



N-glycolyl groups of nonhuman chondroitin sulfates survive in ancient fossils [Biochemistry]

2017-09-11T11:39:44-07:00

Biosynthesis of the common mammalian sialic acid N-glycolylneuraminic acid (Neu5Gc) was lost during human evolution due to inactivation of the CMAH gene, possibly expediting divergence of the Homo lineage, due to a partial fertility barrier. Neu5Gc catabolism generates N-glycolylhexosamines, which are potential precursors for glycoconjugate biosynthesis. We carried out metabolic...



Evolution of flexibility and rigidity in retaliatory punishment [Psychological and Cognitive Sciences]

2017-09-11T11:39:44-07:00

Natural selection designs some social behaviors to depend on flexible learning processes, whereas others are relatively rigid or reflexive. What determines the balance between these two approaches? We offer a detailed case study in the context of a two-player game with antisocial behavior and retaliatory punishment. We show that each...



Thomas E. Starzl: Transplantation pioneer [Retrospectives]

2017-09-11T11:39:44-07:00

Thomas E. Starzl, MD, PhD was born on March 11, 1926 in Le Mars, Iowa, the second son of Roman Frederick Starzl and Anna Laura Starzl. His parents were first-generation Americans, the children of Czechoslovakian and Irish immigrants. Roman Starzl was an editor, publisher, and owner of a newspaper. Anna...



Engineering a light-activated caspase-3 for precise ablation of neurons in vivo [Biochemistry]

2017-09-11T11:39:44-07:00

The circuitry of the brain is characterized by cell heterogeneity, sprawling cellular anatomy, and astonishingly complex patterns of connectivity. Determining how complex neural circuits control behavior is a major challenge that is often approached using surgical, chemical, or transgenic approaches to ablate neurons. However, all these approaches suffer from a...



Cortically coordinated NREM thalamocortical oscillations play an essential, instructive role in visual system plasticity [Neuroscience]

2017-09-11T11:39:45-07:00

Two long-standing questions in neuroscience are how sleep promotes brain plasticity and why some forms of plasticity occur preferentially during sleep vs. wake. Establishing causal relationships between specific features of sleep (e.g., network oscillations) and sleep-dependent plasticity has been difficult. Here we demonstrate that presentation of a novel visual stimulus...



Disassembly of the Staphylococcus aureus hibernating 100S ribosome by an evolutionarily conserved GTPase [Biochemistry]

2017-09-11T11:39:45-07:00

The bacterial hibernating 100S ribosome is a poorly understood form of the dimeric 70S particle that has been linked to pathogenesis, translational repression, starvation responses, and ribosome turnover. In the opportunistic pathogen Staphylococcus aureus and most other bacteria, hibernation-promoting factor (HPF) homodimerizes the 70S ribosomes to form a translationally silent...



Intestinal type 1 regulatory T cells migrate to periphery to suppress diabetogenic T cells and prevent diabetes development [Immunology and Inflammation]

2017-09-11T11:39:45-07:00

Growing insight into the pathogenesis of autoimmune diseases and numerous studies in preclinical models highlights the potential of regulatory T cells to restore tolerance. By using non-obese diabetic (NOD) BDC2.5 TCR-transgenic (Tg), and IL-10 and Foxp3 double-reporter mice, we demonstrate that alteration of gut microbiota during cohousing experiments or treatment...



Universal nanodroplet branches from confining the Ouzo effect [Applied Physical Sciences]

2017-09-11T11:39:46-07:00

We report the self-organization of universal branching patterns of oil nanodroplets under the Ouzo effect [Vitale S, Katz J (2003) Langmuir 19:4105–4110]—a phenomenon in which spontaneous droplet formation occurs upon dilution of an organic solution of oil with water. The mixing of the organic and aqueous phases is confined under...



Reexamining the origin of the directionality of myosin V [Biophysics and Computational Biology]

2017-09-11T11:39:46-07:00

The nature of the conversion of chemical energy to directional motion in myosin V is examined by careful simulations that include two complementary methods: direct Langevin Dynamics (LD) simulations with a scaled-down potential that provided a detailed time-resolved mechanism, and kinetic equations solution for the ensemble long-time propagation (based on...



Waiting can be an optimal conservation strategy, even in a crisis discipline [Sustainability Science]

2017-09-11T11:39:46-07:00

Biodiversity conservation projects confront immediate and escalating threats with limited funding. Conservation theory suggests that the best response to the species extinction crisis is to spend money as soon as it becomes available, and this is often an explicit constraint placed on funding. We use a general dynamic model of...



Varicose and cheerio collaborate with pebble to mediate semaphorin-1a reverse signaling in Drosophila [Neuroscience]

2017-09-11T11:39:46-07:00

The transmembrane semaphorin Sema-1a acts as both a ligand and a receptor to regulate axon–axon repulsion during neural development. Pebble (Pbl), a Rho guanine nucleotide exchange factor, mediates Sema-1a reverse signaling through association with the N-terminal region of the Sema-1a intracellular domain (ICD), resulting in cytoskeletal reorganization. Here, we uncover...



Structural and hydrodynamic properties of an intrinsically disordered region of a germ cell-specific protein on phase separation [Biophysics and Computational Biology]

2017-09-11T11:39:47-07:00

Membrane encapsulation is frequently used by the cell to sequester biomolecules and compartmentalize their function. Cells also concentrate molecules into phase-separated protein or protein/nucleic acid “membraneless organelles” that regulate a host of biochemical processes. Here, we use solution NMR spectroscopy to study phase-separated droplets formed from the intrinsically disordered N-terminal...



RABIF/MSS4 is a Rab-stabilizing holdase chaperone required for GLUT4 exocytosis [Cell Biology]

2017-09-11T11:39:47-07:00

Rab GTPases are switched from their GDP-bound inactive conformation to a GTP-bound active state by guanine nucleotide exchange factors (GEFs). The first putative GEFs isolated for Rabs are RABIF (Rab-interacting factor)/MSS4 (mammalian suppressor of Sec4) and its yeast homolog DSS4 (dominant suppressor of Sec4). However, the biological function and molecular...



Genetic disruption of ankyrin-G in adult mouse forebrain causes cortical synapse alteration and behavior reminiscent of bipolar disorder [Neuroscience]

2017-09-11T11:39:47-07:00

Genome-wide association studies have implicated the ANK3 locus in bipolar disorder, a major human psychotic illness. ANK3 encodes ankyrin-G, which organizes the neuronal axon initial segment (AIS). We generated a mouse model with conditional disruption of ANK3 in pyramidal neurons of the adult forebrain (Ank-G cKO). This resulted in the...



Trichromacy increases fruit intake rates of wild capuchins (Cebus capucinus imitator) [Anthropology]

2017-09-11T11:39:47-07:00

Intraspecific color vision variation is prevalent among nearly all diurnal monkeys in the neotropics and is seemingly a textbook case of balancing selection acting to maintain genetic polymorphism. Clear foraging advantages to monkeys with trichromatic vision over those with dichromatic “red-green colorblind” vision have been observed in captive studies; however,...



Samd7 is a cell type-specific PRC1 component essential for establishing retinal rod photoreceptor identity [Neuroscience]

2017-09-12T13:19:42-07:00

Precise transcriptional regulation controlled by a transcription factor network is known to be crucial for establishing correct neuronal cell identities and functions in the CNS. In the retina, the expression of various cone and rod photoreceptor cell genes is regulated by multiple transcription factors; however, the role of epigenetic regulation...



Modeling Parkinson’s disease pathology by combination of fibril seeds and {alpha}-synuclein overexpression in the rat brain [Neuroscience]

2017-09-12T13:19:42-07:00

Although a causative role of α-synuclein (α-syn) is well established in Parkinson’s disease pathogenesis, available animal models of synucleinopathy do not replicate the full range of cellular and behavioral changes characteristic of the human disease. This study was designed to generate a more faithful model of Parkinson’s disease by injecting...



Local optical control of ferromagnetism and chemical potential in a topological insulator [Physics]

2017-09-12T13:19:42-07:00

Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb)2Te3 grown on SrTiO3. By optically modulating the coercivity of the films, we...



Network of microbial and antibiotic interactions drive colonization and infection with multidrug-resistant organisms [Medical Sciences]

2017-09-12T13:19:43-07:00

The emergence and spread of multidrug-resistant organisms (MDROs) across global healthcare networks poses a serious threat to hospitalized individuals. Strategies to limit the emergence and spread of MDROs include oversight to decrease selective pressure for MDROs by promoting appropriate antibiotic use via antibiotic stewardship programs. However, restricting the use of...



E46K {alpha}-synuclein pathological mutation causes cell-autonomous toxicity without altering protein turnover or aggregation [Neuroscience]

2017-09-12T13:19:43-07:00

α-Synuclein (aSyn) is the main driver of neurodegenerative diseases known as “synucleinopathies,” but the mechanisms underlying this toxicity remain poorly understood. To investigate aSyn toxic mechanisms, we have developed a primary neuronal model in which a longitudinal survival analysis can be performed by following the overexpression of fluorescently tagged WT...



Targeting CXCR4-dependent immunosuppressive Ly6Clow monocytes improves antiangiogenic therapy in colorectal cancer [Medical Sciences]

2017-09-12T13:19:43-07:00

Antiangiogenic therapy with antibodies against VEGF (bevacizumab) or VEGFR2 (ramucirumab) has been proven efficacious in colorectal cancer (CRC) patients. However, the improvement in overall survival is modest and only in combination with chemotherapy. Thus, there is an urgent need to identify potential underlying mechanisms of resistance specific to antiangiogenic therapy...



On the origin of shape fluctuations of the cell nucleus [Applied Physical Sciences]

2017-09-12T13:19:44-07:00

The nuclear envelope (NE) presents a physical boundary between the cytoplasm and the nucleoplasm, sandwiched in between two highly active systems inside the cell: cytoskeleton and chromatin. NE defines the shape and size of the cell nucleus, which increases during the cell cycle, accommodating for chromosome decondensation followed by genome...



Prior expectations induce prestimulus sensory templates [Psychological and Cognitive Sciences]

2017-09-12T13:19:44-07:00

Perception can be described as a process of inference, integrating bottom-up sensory inputs and top-down expectations. However, it is unclear how this process is neurally implemented. It has been proposed that expectations lead to prestimulus baseline increases in sensory neurons tuned to the expected stimulus, which in turn, affect the...



Meta-analysis of field experiments shows no change in racial discrimination in hiring over time [Social Sciences]

2017-09-12T13:19:44-07:00

This study investigates change over time in the level of hiring discrimination in US labor markets. We perform a meta-analysis of every available field experiment of hiring discrimination against African Americans or Latinos (n = 28). Together, these studies represent 55,842 applications submitted for 26,326 positions. We focus on trends...



Optimal deployment of resources for maximizing impact in spreading processes [Social Sciences]

2017-09-12T13:19:44-07:00

The effective use of limited resources for controlling spreading processes on networks is of prime significance in diverse contexts, ranging from the identification of “influential spreaders” for maximizing information dissemination and targeted interventions in regulatory networks, to the development of mitigation policies for infectious diseases and financial contagion in economic...



Robust mechanobiological behavior emerges in heterogeneous myosin systems [Engineering]

2017-09-12T13:19:44-07:00

Biological complexity presents challenges for understanding natural phenomenon and engineering new technologies, particularly in systems with molecular heterogeneity. Such complexity is present in myosin motor protein systems, and computational modeling is essential for determining how collective myosin interactions produce emergent system behavior. We develop a computational approach for altering myosin...



Favored local structures in amorphous colloidal packings measured by microbeam X-ray diffraction [Applied Physical Sciences]

2017-09-13T11:40:56-07:00

Local structure and symmetry are keys to understanding how a material is formed and the properties it subsequently exhibits. This applies to both crystals and amorphous and glassy materials. In the case of amorphous materials, strong links between processing and history, structure and properties have yet to be made because...



Distinct roles for motor neuron autophagy early and late in the SOD1G93A mouse model of ALS [Neuroscience]

2017-09-13T11:40:56-07:00

Mutations in autophagy genes can cause familial and sporadic amyotrophic lateral sclerosis (ALS). However, the role of autophagy in ALS pathogenesis is poorly understood, in part due to the lack of cell type-specific manipulations of this pathway in animal models. Using a mouse model of ALS expressing mutant superoxide dismutase...



RIPK1 mediates a disease-associated microglial response in Alzheimer’s disease [Neuroscience]

2017-09-13T11:40:57-07:00

Dysfunction of microglia is known to play an important role in Alzheimer’s disease (AD). Here, we investigated the role of RIPK1 in microglia mediating the pathogenesis of AD. RIPK1 is highly expressed by microglial cells in human AD brains. Using the amyloid precursor protein (APP)/presenilin 1 (PS1) transgenic mouse model,...



Network approach to patterns in stratocumulus clouds [Earth, Atmospheric, and Planetary Sciences]

2017-09-13T11:40:57-07:00

Stratocumulus clouds (Sc) have a significant impact on the amount of sunlight reflected back to space, with important implications for Earth’s climate. Representing Sc and their radiative impact is one of the largest challenges for global climate models. Sc fields self-organize into cellular patterns and thus lend themselves to analysis...



Reply to Nash: Color terms are lost, despite missing data [Letters (Online Only)]

2017-09-14T12:51:56-07:00

David Nash (1) calls into question our findings (2) that color terms are likely lost as well as gained, citing questions about the semantics of certain lexical items, treatment of unattested items, and, crucially, problems with missing (vs. absent) data in Bayesian phylogenetic models. For ancestral state reconstructions to be...



Reply to Jin and Zhu: PINOID-mediated COP1 phosphorylation matters in photomorphogenesis in Arabidopsis [Letters (Online Only)]

2017-09-14T15:33:54-07:00

We thank Jin and Zhu for their comments (1). Our study in PNAS focuses on the molecular role for PINOID (PID) and PID-mediated CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) phosphorylation in the regulation of seedling development in Arabidopsis (2). Not only hypocotyl elongation but also apical hook maintenance and cotyledon aperture are...



Role of PINOID-mediated COP1 phosphorylation in Arabidopsis photomorphogenesis is overemphasized [Letters (Online Only)]

2017-09-14T16:29:06-07:00

Etiolated Arabidopsis seedlings have long hypocotyls and closed yellow cotyledons (skotomorphogenesis); however, light-grown plants exhibit short hypocotyls and opened green cotyledons (photomorphogenesis) (1). It has been revealed that E3 ubiquitin ligase CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) is a central negative regulator for plant photomorphogenesis. COP1 directly targets a plethora of transcription...



Loss of color terms not demonstrated [Letters (Online Only)]

2017-09-14T14:03:47-07:00

Haynie and Bowern (H&B) (1) use promising computational phylogenetic methods to test the standard view of color terminology structure, epitomized in the World Color Survey (WCS) (2). H&B matched Bayesian phylogenies for 189 Pama–Nyungan languages with the color terms in each vocabulary. Their inferred ancestral state reconstructions found the expected...



Well below 2 {degrees}C: Mitigation strategies for avoiding dangerous to catastrophic climate changes [Perspectives]

2017-09-15T11:51:13-07:00

The historic Paris Agreement calls for limiting global temperature rise to “well below 2 °C.” Because of uncertainties in emission scenarios, climate, and carbon cycle feedback, we interpret the Paris Agreement in terms of three climate risk categories and bring in considerations of low-probability (5%) high-impact (LPHI) warming in addition...



Diverse p53/DNA binding modes expand the repertoire of p53 response elements [Biochemistry]

2017-09-14T11:39:17-07:00

The tumor suppressor protein p53 acts as a transcription factor, binding sequence-specifically to defined DNA sites, thereby activating the expression of genes leading to diverse cellular outcomes. Canonical p53 response elements (REs) are made of two decameric half-sites separated by a variable number of base pairs (spacers). Fifty percent of...



Reply to Pluss et al.: The strength of PEMapper/PECaller lies in unbiased calling using large sample sizes [Letters (Online Only)]

2017-09-15T13:07:55-07:00

In a recent Letter in PNAS (1), Plüss et al. compare the speed and accuracy of the Burrows–Wheeler aligner (BWA) (2)/Genome Analysis Toolkit (GATK) (3) best-practices pipeline (4), against our PEMapper/PECaller pipeline (5), as well as against a commercially available, but un–peer-reviewed method called GENALICEMAP (genalice.com). This test was conducted...



Need for speed in accurate whole-genome data analysis: GENALICE MAP challenges BWA/GATK more than PEMapper/PECaller and Isaac [Letters (Online Only)]

2017-09-15T14:31:03-07:00

In the current high-throughput genomics era, efficient and accurate analysis of large-scale whole-genome sequencing (WGS) data constitutes a computational bottleneck. Johnston et al. (1) introduce the PEMapper/PECaller software package for short-read WGS alignment and variant calling, promising faster analyses with reduced output file sizes and “nearly identical (or better)” variant...



IL-4-producing B cells regulate T helper cell dichotomy in type 1- and type 2-controlled diseases [Immunology and Inflammation]

2017-09-15T11:51:12-07:00

Interleukin-4 (IL-4)–induced T helper (Th) 2 cells promote susceptibility to the protozoan parasite Leishmania major, while conferring immunity to the intestinal trematode Schistosoma mansoni. Here, we report that abrogation of IL-4 receptor alpha (IL-4Rα) signaling on B cells in BALB/c mice (mb1creIL-4Rα–/lox) transformed nonhealer BALB/c to a healer phenotype with...



Clonal expansion and epigenetic reprogramming following deletion or amplification of mutant IDH1 [Medical Sciences]

2017-09-15T11:51:13-07:00

IDH1 mutation is the earliest genetic alteration in low-grade gliomas (LGGs), but its role in tumor recurrence is unclear. Mutant IDH1 drives overproduction of the oncometabolite d-2-hydroxyglutarate (2HG) and a CpG island (CGI) hypermethylation phenotype (G-CIMP). To investigate the role of mutant IDH1 at recurrence, we performed a longitudinal analysis...



Functional screening in human cardiac organoids reveals a metabolic mechanism for cardiomyocyte cell cycle arrest [Developmental Biology]

2017-09-15T11:51:13-07:00

The mammalian heart undergoes maturation during postnatal life to meet the increased functional requirements of an adult. However, the key drivers of this process remain poorly defined. We are currently unable to recapitulate postnatal maturation in human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs), limiting their potential as a model system to...



Mechanosensing drives acuity of {alpha}{beta} T-cell recognition [Biophysics and Computational Biology]

2017-08-15T09:41:51-07:00

T lymphocytes use surface αβ T-cell receptors (TCRs) to recognize peptides bound to MHC molecules (pMHCs) on antigen-presenting cells (APCs). How the exquisite specificity of high-avidity T cells is achieved is unknown but essential, given the paucity of foreign pMHC ligands relative to the ubiquitous self-pMHC array on an APC....



Phenological synchronization disrupts trophic interactions between Kodiak brown bears and salmon [Ecology]

2017-08-21T12:06:06-07:00

Climate change is altering the seasonal timing of life cycle events in organisms across the planet, but the magnitude of change often varies among taxa [Thackeray SJ, et al. (2016) Nature 535:241–245]. This can cause the temporal relationships among species to change, altering the strength of interaction. A large body...



Single-cell functional and chemosensitive profiling of combinatorial colorectal therapy in zebrafish xenografts [Medical Sciences]

2017-08-23T11:33:34-07:00

Cancer is as unique as the person fighting it. With the exception of a few biomarker-driven therapies, patients go through rounds of trial-and-error approaches to find the best treatment. Using patient-derived cell lines, we show that zebrafish larvae xenotransplants constitute a fast and highly sensitive in vivo model for differential...



Fishing for answers in precision cancer medicine [Commentaries]

2017-09-18T11:45:36-07:00

Zebrafish Xenotransplants Enter Precision Oncology “Which drug should I prescribe to the cancer patient in front of me?” This question is an inevitable riddle for many oncologists. While the list of US Food and Drug Administration-approved biomarker-driven targeted therapies in oncology grows every year, and clinical trials for new immunotherapy...



Americans misperceive racial economic equality [Psychological and Cognitive Sciences]

2017-09-18T11:45:24-07:00

The present research documents the widespread misperception of race-based economic equality in the United States. Across four studies (n = 1,377) sampling White and Black Americans from the top and bottom of the national income distribution, participants overestimated progress toward Black–White economic equality, largely driven by estimates of greater current...



Critical role of caveolin-1 in ocular neovascularization and multitargeted antiangiogenic effects of cavtratin via JNK [Medical Sciences]

2017-09-18T11:45:24-07:00

Ocular neovascularization is a devastating pathology of numerous ocular diseases and is a major cause of blindness. Caveolin-1 (Cav-1) plays important roles in the vascular system. However, little is known regarding its function and mechanisms in ocular neovascularization. Here, using comprehensive model systems and a cell permeable peptide of Cav-1,...



Extinction risk is most acute for the world’s largest and smallest vertebrates [Ecology]

2017-09-18T11:45:24-07:00

Extinction risk in vertebrates has been linked to large body size, but this putative relationship has only been explored for select taxa, with variable results. Using a newly assembled and taxonomically expansive database, we analyzed the relationships between extinction risk and body mass (27,647 species) and between extinction risk and...



Continuous track paths reveal additive evidence integration in multistep decision making [Psychological and Cognitive Sciences]

2017-09-18T11:45:25-07:00

Multistep decision making pervades daily life, but its underlying mechanisms remain obscure. We distinguish four prominent models of multistep decision making, namely serial stage, hierarchical evidence integration, hierarchical leaky competing accumulation (HLCA), and probabilistic evidence integration (PEI). To empirically disentangle these models, we design a two-step reward-based decision paradigm and...



Multiple interactions between an Arf/GEF complex and charged lipids determine activation kinetics on the membrane [Biophysics and Computational Biology]

2017-09-18T11:45:25-07:00

Lipidated small GTPases and their regulators need to bind to membranes to propagate actions in the cell, but an integrated understanding of how the lipid bilayer exerts its effect has remained elusive. Here we focused on ADP ribosylation factor (Arf) GTPases, which orchestrate a variety of regulatory functions in lipid...



MicroRNA dysregulation to identify therapeutic target combinations for chronic lymphocytic leukemia [Medical Sciences]

2017-09-18T11:45:25-07:00

Loss of miR-15/16 is the most common genetic lesion in chronic lymphocytic leukemia (CLL), promoting overexpression of BCL2, which factors in leukemia pathogenesis. Indeed, an inhibitor of Bcl2, venetoclcax, is highly active in the treatment of patients with CLL. However, single-agent venetoclcax fails to eradicate minimal residual disease in most...



Color naming across languages reflects color use [Psychological and Cognitive Sciences]

2017-09-18T11:45:25-07:00

What determines how languages categorize colors? We analyzed results of the World Color Survey (WCS) of 110 languages to show that despite gross differences across languages, communication of chromatic chips is always better for warm colors (yellows/reds) than cool colors (blues/greens). We present an analysis of color statistics in a...



TrkB neurotrophic activities are blocked by {alpha}-synuclein, triggering dopaminergic cell death in Parkinson’s disease [Neuroscience]

2017-09-18T11:45:25-07:00

BDNF/TrkB neurotrophic signaling is essential for dopaminergic neuronal survival, and the activities are reduced in the substantial nigra (SN) of Parkinson’s disease (PD). However, whether α-Syn (alpha-synuclein) aggregation, a hallmark in the remaining SN neurons in PD, accounts for the neurotrophic inhibition remains elusive. Here we show that α-Syn selectively...



Hydrologic regulation of plant rooting depth [Ecology]

2017-09-18T11:45:26-07:00

Plant rooting depth affects ecosystem resilience to environmental stress such as drought. Deep roots connect deep soil/groundwater to the atmosphere, thus influencing the hydrologic cycle and climate. Deep roots enhance bedrock weathering, thus regulating the long-term carbon cycle. However, we know little about how deep roots go and why. Here,...



Near-atomic structure of jasplakinolide-stabilized malaria parasite F-actin reveals the structural basis of filament instability [Biophysics and Computational Biology]

2017-09-18T11:45:26-07:00

During their life cycle, apicomplexan parasites, such as the malaria parasite Plasmodium falciparum, use actomyosin-driven gliding motility to move and invade host cells. For this process, actin filament length and stability are temporally and spatially controlled. In contrast to canonical actin, P. falciparum actin 1 (PfAct1) does not readily polymerize...



Exposure to seismic air gun signals causes physiological harm and alters behavior in the scallop Pecten fumatus [Sustainability Science]

2017-09-18T11:45:26-07:00

Seismic surveys map the seabed using intense, low-frequency sound signals that penetrate kilometers into the Earth’s crust. Little is known regarding how invertebrates, including economically and ecologically important bivalves, are affected by exposure to seismic signals. In a series of field-based experiments, we investigate the impact of exposure to seismic...



Host modification of a bacterial quorum-sensing signal induces a phenotypic switch in bacterial symbionts [Microbiology]

2017-09-18T11:45:26-07:00

Bacterial communities colonize epithelial surfaces of most animals. Several factors, including the innate immune system, mucus composition, and diet, have been identified as determinants of host-associated bacterial communities. Here we show that the early branching metazoan Hydra is able to modify bacterial quorum-sensing signals. We identified a eukaryotic mechanism that...



MIF and D-DT are potential disease severity modifiers in male MS subjects [Immunology and Inflammation]

2017-09-18T11:45:27-07:00

Little is known about mechanisms that drive the development of progressive multiple sclerosis (MS), although inflammatory factors, such as macrophage migration inhibitory factor (MIF), its homolog D-dopachrome tautomerase (D-DT), and their common receptor CD74 may contribute to disease worsening. Our findings demonstrate elevated MIF and D-DT levels in males with...



Transparent, conformable, active multielectrode array using organic electrochemical transistors [Applied Physical Sciences]

2017-09-18T11:45:27-07:00

Mechanically flexible active multielectrode arrays (MEA) have been developed for local signal amplification and high spatial resolution. However, their opaqueness limited optical observation and light stimulation during use. Here, we show a transparent, ultraflexible, and active MEA, which consists of transparent organic electrochemical transistors (OECTs) and transparent Au grid wirings....



Exceptionally tight membrane-binding may explain the key role of the synaptotagmin-7 C2A domain in asynchronous neurotransmitter release [Neuroscience]

2017-09-18T11:45:27-07:00

Synaptotagmins (Syts) act as Ca2+ sensors in neurotransmitter release by virtue of Ca2+-binding to their two C2 domains, but their mechanisms of action remain unclear. Puzzlingly, Ca2+-binding to the C2B domain appears to dominate Syt1 function in synchronous release, whereas Ca2+-binding to the C2A domain mediates Syt7 function in asynchronous...



Copper nanoparticle ensembles for selective electroreduction of CO2 to C2-C3 products [Chemistry]

2017-09-18T11:45:27-07:00

Direct conversion of carbon dioxide to multicarbon products remains as a grand challenge in electrochemical CO2 reduction. Various forms of oxidized copper have been demonstrated as electrocatalysts that still require large overpotentials. Here, we show that an ensemble of Cu nanoparticles (NPs) enables selective formation of C2–C3 products at low...



Endothelial insulin receptors differentially control insulin signaling kinetics in peripheral tissues and brain of mice [Medical Sciences]

2017-09-18T11:45:28-07:00

Insulin receptors (IRs) on endothelial cells may have a role in the regulation of transport of circulating insulin to its target tissues; however, how this impacts on insulin action in vivo is unclear. Using mice with endothelial-specific inactivation of the IR gene (EndoIRKO), we find that in response to systemic...



Cell cycle-targeting microRNAs promote differentiation by enforcing cell-cycle exit [Developmental Biology]

2017-09-18T11:45:28-07:00

MicroRNAs (miRNAs) have been known to affect various biological processes by repressing expression of specific genes. Here we describe an essential function of the miR-34/449 family during differentiation of epithelial cells. We found that miR-34/449 suppresses the cell-cycle machinery in vivo and promotes cell-cycle exit, thereby allowing epithelial cell differentiation....



Longitudinal identification of clinically distinct neurophenotypes in young children with fragile X syndrome [Neuroscience]

2017-09-18T11:45:28-07:00

Fragile X syndrome (FXS), due to mutations of the FMR1 gene, is the most common known inherited cause of developmental disability. The cognitive, behavioral, and neurological phenotypes observed in affected individuals can vary considerably, making it difficult to predict outcomes and determine the need for interventions. We sought to examine...



Evolutionary diversification of protein-protein interactions by interface add-ons [Biochemistry]

2017-09-18T11:45:28-07:00

Cells contain a multitude of protein complexes whose subunits interact with high specificity. However, the number of different protein folds and interface geometries found in nature is limited. This raises the question of how protein–protein interaction specificity is achieved on the structural level and how the formation of nonphysiological complexes...



Retinoid X receptor suppresses a metastasis-promoting transcriptional program in myeloid cells via a ligand-insensitive mechanism [Immunology and Inflammation]

2017-09-18T11:45:28-07:00

Retinoid X receptor (RXR) regulates several key functions in myeloid cells, including inflammatory responses, phagocytosis, chemokine secretion, and proangiogenic activity. Its importance, however, in tumor-associated myeloid cells is unknown. In this study, we demonstrate that deletion of RXR in myeloid cells enhances lung metastasis formation while not affecting primary tumor...