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Preview: Proceedings of the National Academy of Sciences recent issues

Proceedings of the National Academy of Sciences recent issues



Proceedings of the National Academy of Sciences RSS feed -- recent issues



 



In This Issue [This Week in PNAS]

2017-06-20T09:04:16-07:00

Origin of rice domestication 3D image of rice bulliform phytolith from the Shangshan site. Researchers have previously reported that microscopic bodies of silica, called phytoliths, from rice (Oryza saliva L.) found at the Shangshan site in the Lower Yangtze of China might represent the earliest example of rice cultivation. However,...



Informational content of relative deprivation as a channel linking economic inequality to risk taking [Social Sciences]

2017-06-20T09:04:17-07:00

The evidence that economic inequality (or relative deprivation) increases risk taking, as presented in PNAS by Payne et al. (1), is an insightful addition to a broader literature that finds that relative deprivation has distinct effects on individuals, not the least of which is their happiness, in addition to any...



Reply to van Hoorn: Social comparisons of “enough” are an informational signal [Social Sciences]

2017-06-20T09:04:17-07:00

In response to our article (1), van Hoorn (2) suggests that our analysis focuses too narrowly on perceived need as the mechanism linking inequality to increased risk taking. The author does not dispute the evidence we present for the role of perceived need, but proposes an additional mechanism linking inequality...



Evidence of bias in assessment of fisheries management impacts [Biological Sciences]

2017-06-20T09:04:17-07:00

Melnychuk et al.’s comments in PNAS (1) that successful fisheries management requires the “capacity to limit fishing pressure” and “scientists are generally unanimous in calling for stronger management” echo comments made in many earlier publications. However, their conclusions about specific fisheries and management approaches lack credibility. Their analysis relies on...



Reply to Slooten et al.: Viewing fisheries management challenges in a global context [Biological Sciences]

2017-06-20T09:04:17-07:00

Slooten et al. (1) claim the survey respondents from New Zealand, one of 28 countries considered in our paper in PNAS (2), were strongly biased toward the fishing industry. The six survey responses comprised a range of background experience: three government/science respondents (added here as coauthors), including the National Institute...



Social determinants of health and the International Monetary Fund [Economic Sciences]

2017-06-20T09:04:16-07:00

Education is considered an important social determinant of health (1, 2). Higher levels of educational attainment appear to be health-enhancing for those who have them (3), and provide intergenerational health benefits for their children (4) as well as their parents (5). Increased knowledge and skills leading to higher wages, as...



Sensory and cognitive adaptations to social living in insect societies [Evolution]

2017-06-20T09:04:16-07:00

A key question in evolutionary biology is to explain the causes and consequences of the so-called “major transitions in evolution,” which resulted in the progressive evolution of cells, organisms, and animal societies (1–3). Several studies, for example, have now aimed to determine which suite of adaptive changes occurred following the...



Stratospheric ozone over the United States in summer linked to observations of convection and temperature via chlorine and bromine catalysis [Earth, Atmospheric, and Planetary Sciences]

2017-06-20T09:04:17-07:00

We present observations defining (i) the frequency and depth of convective penetration of water into the stratosphere over the United States in summer using the Next-Generation Radar system; (ii) the altitude-dependent distribution of inorganic chlorine established in the same coordinate system as the radar observations; (iii) the high resolution temperature...



Modeling gene regulation from paired expression and chromatin accessibility data [Biophysics and Computational Biology]

2017-06-20T09:04:17-07:00

The rapid increase of genome-wide datasets on gene expression, chromatin states, and transcription factor (TF) binding locations offers an exciting opportunity to interpret the information encoded in genomes and epigenomes. This task can be challenging as it requires joint modeling of context-specific activation of cis-regulatory elements (REs) and the effects...



Mitochondrial dysfunction induced by a SH2 domain-targeting STAT3 inhibitor leads to metabolic synthetic lethality in cancer cells [Cell Biology]

2017-06-20T09:04:17-07:00

In addition to its canonical role in nuclear transcription, signal transducer and activator of transcription 3 (STAT3) is emerging as an important regulator of mitochondrial function. Here, we demonstrate that a novel inhibitor that binds with high affinity to the STAT3 SH2 domain triggers a complex cascade of events initiated...



Neurog2 and Ascl1 together regulate a postmitotic derepression circuit to govern laminar fate specification in the murine neocortex [Developmental Biology]

2017-06-20T09:04:17-07:00

A derepression mode of cell-fate specification involving the transcriptional repressors Tbr1, Fezf2, Satb2, and Ctip2 operates in neocortical projection neurons to specify six layer identities in sequence. Less well understood is how laminar fate transitions are regulated in cortical progenitors. The proneural genes Neurog2 and Ascl1 cooperate in progenitors to...



Probabilistic model predicts dynamics of vegetation biomass in a desert ecosystem in NW China [Ecology]

2017-06-20T09:04:17-07:00

The temporal dynamics of vegetation biomass are of key importance for evaluating the sustainability of arid and semiarid ecosystems. In these ecosystems, biomass and soil moisture are coupled stochastic variables externally driven, mainly, by the rainfall dynamics. Based on long-term field observations in northwestern (NW) China, we test a recently...



Transposon mutagenesis identifies chromatin modifiers cooperating with Ras in thyroid tumorigenesis and detects ATXN7 as a cancer gene [Genetics]

2017-06-20T09:04:17-07:00

Oncogenic RAS mutations are present in 15–30% of thyroid carcinomas. Endogenous expression of mutant Ras is insufficient to initiate thyroid tumorigenesis in murine models, indicating that additional genetic alterations are required. We used Sleeping Beauty (SB) transposon mutagenesis to identify events that cooperate with HrasG12V in thyroid tumor development. Random...



An Exportin-1-dependent microRNA biogenesis pathway during human cell quiescence [Genetics]

2017-06-20T09:04:17-07:00

The reversible state of proliferative arrest known as “cellular quiescence” plays an important role in tissue homeostasis and stem cell biology. By analyzing the expression of miRNAs and miRNA-processing factors during quiescence in primary human fibroblasts, we identified a group of miRNAs that are induced during quiescence despite markedly reduced...



Treatment with diphenyl-pyrazole compound anle138b/c reveals that {alpha}-synuclein protects melanoma cells from autophagic cell death [Medical Sciences]

2017-06-20T09:04:17-07:00

Recent epidemiological and clinical studies have reported a significantly increased risk for melanoma in people with Parkinson’s disease. Because no evidence could be obtained that genetic factors are the reason for the association between these two diseases, we hypothesized that of the three major Parkinson’s disease-related proteins—α-synuclein, LRRK2, and Parkin—α-synuclein...



Reconstitution of a minimal machinery capable of assembling periplasmic type IV pili [Microbiology]

2017-06-20T09:04:17-07:00

Type IV pili (Tfp), which are key virulence factors in many bacterial pathogens, define a large group of multipurpose filamentous nanomachines widespread in Bacteria and Archaea. Tfp biogenesis is a complex multistep process, which relies on macromolecular assemblies composed of 15 conserved proteins in model gram-negative species. To improve our...



High-mobility group box-1 as an autocrine trophic factor in white matter stroke [Neuroscience]

2017-06-20T09:04:17-07:00

Maintenance of white matter integrity in health and disease is critical for a variety of neural functions. Ischemic stroke in the white matter frequently results in degeneration of oligodendrocytes (OLs) and myelin. Previously, we found that toll-like receptor 2 (TLR2) expressed in OLs provides cell-autonomous protective effects on ischemic OL...



Dynamic changes in murine forebrain miR-211 expression associate with cholinergic imbalances and epileptiform activity [Neuroscience]

2017-06-20T09:04:17-07:00

Epilepsy is a common neurological disease, manifested in unprovoked recurrent seizures. Epileptogenesis may develop due to genetic or pharmacological origins or following injury, but it remains unclear how the unaffected brain escapes this susceptibility to seizures. Here, we report that dynamic changes in forebrain microRNA (miR)-211 in the mouse brain...



Chemical probes to potently and selectively inhibit endocannabinoid cellular reuptake [Pharmacology]

2017-06-20T09:04:17-07:00

The extracellular effects of the endocannabinoids anandamide and 2-arachidonoyl glycerol are terminated by enzymatic hydrolysis after crossing cellular membranes by facilitated diffusion. The lack of potent and selective inhibitors for endocannabinoid transport has prevented the molecular characterization of this process, thus hindering its biochemical investigation and pharmacological exploitation. Here, we...



Assessing elements of an extended evolutionary synthesis for plant domestication and agricultural origin research [Anthropology]

2017-06-20T09:04:16-07:00

The development of agricultural societies, one of the most transformative events in human and ecological history, was made possible by plant and animal domestication. Plant domestication began 12,000–10,000 y ago in a number of major world areas, including the New World tropics, Southwest Asia, and China, during a period of...



Dating rice remains through phytolith carbon-14 study reveals domestication at the beginning of the Holocene [Anthropology]

2017-06-20T09:04:16-07:00

Phytolith remains of rice (Oryza sativa L.) recovered from the Shangshan site in the Lower Yangtze of China have previously been recognized as the earliest examples of rice cultivation. However, because of the poor preservation of macroplant fossils, many radiocarbon dates were derived from undifferentiated organic materials in pottery sherds....



Ambient nitrogen reduction cycle using a hybrid inorganic-biological system [Applied Biological Sciences]

2017-06-20T09:04:16-07:00

We demonstrate the synthesis of NH3 from N2 and H2O at ambient conditions in a single reactor by coupling hydrogen generation from catalytic water splitting to a H2-oxidizing bacterium Xanthobacter autotrophicus, which performs N2 and CO2 reduction to solid biomass. Living cells of X. autotrophicus may be directly applied as...



Catalytic-site design for inverse heavy-enzyme isotope effects in human purine nucleoside phosphorylase [Biochemistry]

2017-06-20T09:04:16-07:00

Heavy-enzyme isotope effects (15N-, 13C-, and 2H-labeled protein) explore mass-dependent vibrational modes linked to catalysis. Transition path-sampling (TPS) calculations have predicted femtosecond dynamic coupling at the catalytic site of human purine nucleoside phosphorylase (PNP). Coupling is observed in heavy PNPs, where slowed barrier crossing caused a normal heavy-enzyme isotope effect...



Crystal structure of tubulin tyrosine ligase-like 3 reveals essential architectural elements unique to tubulin monoglycylases [Biochemistry]

2017-06-20T09:04:17-07:00

Glycylation and glutamylation, the posttranslational addition of glycines and glutamates to genetically encoded glutamates in the intrinsically disordered tubulin C-terminal tails, are crucial for the biogenesis and stability of cilia and flagella and play important roles in metazoan development. Members of the diverse family of tubulin tyrosine ligase-like (TTLL) enzymes...



Characterization of the macrocyclase involved in the biosynthesis of RiPP cyclic peptides in plants [Biochemistry]

2017-06-20T09:04:17-07:00

Enzymes that can catalyze the macrocyclization of linear peptide substrates have long been sought for the production of libraries of structurally diverse scaffolds via combinatorial gene assembly as well as to afford rapid in vivo screening methods. Orbitides are plant ribosomally synthesized and posttranslationally modified peptides (RiPPs) of various sizes...



Crystal structures of the Burkholderia multivorans hopanoid transporter HpnN [Biochemistry]

2017-06-20T09:04:17-07:00

Strains of the Burkholderia cepacia complex (Bcc) are Gram-negative opportunisitic bacteria that are capable of causing serious diseases, mainly in immunocompromised individuals. Bcc pathogens are intrinsically resistant to multiple antibiotics, including β-lactams, aminoglycosides, fluoroquinolones, and polymyxins. They are major pathogens in patients with cystic fibrosis (CF) and can cause severe...



Phage display and kinetic selection of antibodies that specifically inhibit amyloid self-replication [Biophysics and Computational Biology]

2017-06-20T09:04:16-07:00

The aggregation of the amyloid β peptide (Aβ) into amyloid fibrils is a defining characteristic of Alzheimer’s disease. Because of the complexity of this aggregation process, effective therapeutic inhibitors will need to target the specific microscopic steps that lead to the production of neurotoxic species. We introduce a strategy for...



Entropy in molecular recognition by proteins [Biophysics and Computational Biology]

2017-06-20T09:04:17-07:00

Molecular recognition by proteins is fundamental to molecular biology. Dissection of the thermodynamic energy terms governing protein–ligand interactions has proven difficult, with determination of entropic contributions being particularly elusive. NMR relaxation measurements have suggested that changes in protein conformational entropy can be quantitatively obtained through a dynamical proxy, but the...



Manipulating the ABCs of self-assembly via low-{chi} block polymer design [Chemistry]

2017-06-20T09:04:16-07:00

Block polymer self-assembly typically translates molecular chain connectivity into mesoscale structure by exploiting incompatible blocks with large interaction parameters (χij). In this article, we demonstrate that the converse approach, encoding low-χ interactions in ABC bottlebrush triblock terpolymers (χAC ≲ 0), promotes organization into a unique mixed-domain lamellar morphology, which we...



Stability of ferrous-iron-rich bridgmanite under reducing midmantle conditions [Earth, Atmospheric, and Planetary Sciences]

2017-06-20T09:04:16-07:00

Our current understanding of the electronic state of iron in lower-mantle minerals leads to a considerable disagreement in bulk sound speed with seismic measurements if the lower mantle has the same composition as the upper mantle (pyrolite). In the modeling studies, the content and oxidation state of Fe in the...



Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods [Earth, Atmospheric, and Planetary Sciences]

2017-06-20T09:04:16-07:00

Although Earth’s climate history is best known through marine records, the corresponding continental climatic conditions drive the evolution of terrestrial life. Continental conditions during the latest Miocene are of particular interest because global faunal turnover is roughly synchronous with a period of global glaciation from ∼6.2–5.5 Ma and with the...



Consequences of rapid ice sheet melting on the Sahelian population vulnerability [Earth, Atmospheric, and Planetary Sciences]

2017-06-20T09:04:16-07:00

The acceleration of ice sheet melting has been observed over the last few decades. Recent observations and modeling studies have suggested that the ice sheet contribution to future sea level rise could have been underestimated in the latest Intergovernmental Panel on Climate Change report. The ensuing freshwater discharge coming from...



Future of fundamental discovery in US biomedical research [Economic Sciences]

2017-06-20T09:04:16-07:00

Young researchers are crucially important for basic science as they make unexpected, fundamental discoveries. Since 1982, we find a steady drop in the number of grant-eligible basic-science faculty [principal investigators (PIs)] younger than 46. This fall occurred over a 32-y period when inflation-corrected congressional funds for NIH almost tripled. During...



Solitary bees reduce investment in communication compared with their social relatives [Evolution]

2017-06-20T09:04:17-07:00

Social animals must communicate to define group membership and coordinate social organization. For social insects, communication is predominantly mediated through chemical signals, and as social complexity increases, so does the requirement for a greater diversity of signals. This relationship is particularly true for advanced eusocial insects, including ants, bees, and...



Recent evolution of extreme cestode growth suppression by a vertebrate host [Evolution]

2017-06-20T09:04:17-07:00

Parasites can be a major cause of natural selection on hosts, which consequently evolve a variety of strategies to avoid, eliminate, or tolerate infection. When ecologically similar host populations present disparate infection loads, this natural variation can reveal immunological strategies underlying adaptation to infection and population divergence. For instance, the...



News Feature: Radiation redux [Immunology and Inflammation]

2017-06-20T09:04:16-07:00

Could traditional radiation treatments work in concert with immunotherapy to mount a more effective assault on cancer? When Michael Postow started his fellowship training in medical oncology at the Memorial Sloan Kettering Cancer Center (MSKCC) in 2010, he wasn’t familiar with the term “abscopal.” Coined decades before he was born...



Functional proteogenomics reveals biomarkers and therapeutic targets in lymphomas [Medical Sciences]

2017-06-20T09:04:17-07:00

Identification of biomarkers and therapeutic targets is a critical goal of precision medicine. N-glycoproteins are a particularly attractive class of proteins that constitute potential cancer biomarkers and therapeutic targets for small molecules, antibodies, and cellular therapies. Using mass spectrometry (MS), we generated a compendium of 1,091 N-glycoproteins (from 40 human...



Effect of water flow and chemical environment on microbiota growth and composition in the human colon [Microbiology]

2017-06-20T09:04:16-07:00

The human gut harbors a dynamic microbial community whose composition bears great importance for the health of the host. Here, we investigate how colonic physiology impacts bacterial growth, which ultimately dictates microbiota composition. Combining measurements of bacterial physiology with analysis of published data on human physiology into a quantitative, comprehensive...



Protein composition of the hepatitis A virus quasi-envelope [Microbiology]

2017-06-20T09:04:17-07:00

The Picornaviridae are a diverse family of RNA viruses including many pathogens of medical and veterinary importance. Classically considered “nonenveloped,” recent studies show that some picornaviruses, notably hepatitis A virus (HAV; genus Hepatovirus) and some members of the Enterovirus genus, are released from cells nonlytically in membranous vesicles. To better...



Asymmetric distribution of type IV pili triggered by directional light in unicellular cyanobacteria [Microbiology]

2017-06-20T09:04:17-07:00

The type IV pili (T4P) system is a supermolecular machine observed in prokaryotes. Cells repeat the cycle of T4P extension, surface attachment, and retraction to drive twitching motility. Although the properties of T4P as a motor have been scrutinized with biophysics techniques, the mechanism of regulation remains unclear. Here we...



Impact of nutrition on social decision making [Neuroscience]

2017-06-20T09:04:16-07:00

Food intake is essential for maintaining homeostasis, which is necessary for survival in all species. However, food intake also impacts multiple biochemical processes that influence our behavior. Here, we investigate the causal relationship between macronutrient composition, its bodily biochemical impact, and a modulation of human social decision making. Across two...



Histamine modulation of the basal ganglia circuitry in the development of pathological grooming [Neuroscience]

2017-06-20T09:04:17-07:00

Aberrant histaminergic function has been proposed as a cause of tic disorders. A rare mutation in the enzyme that produces histamine (HA), histidine decarboxylase (HDC), has been identified in patients with Tourette syndrome (TS). Hdc knockout mice exhibit repetitive behavioral pathology and neurochemical characteristics of TS, establishing them as a...



Sensorimotor integration on a rapid time scale [Neuroscience]

2017-06-20T09:04:17-07:00

Sensing is fundamental to the control of movement: From grasping objects to speech production, sensing guides action. So far, most of our knowledge about sensorimotor integration comes from visually guided reaching and oculomotor integration, in which the time course and trajectories of movements can be measured at a high temporal...



Finally making sense of the double-slit experiment [Physics]

2017-06-20T09:04:16-07:00

Feynman stated that the double-slit experiment “…has in it the heart of quantum mechanics. In reality, it contains the only mystery” and that “nobody can give you a deeper explanation of this phenomenon than I have given; that is, a description of it” [Feynman R, Leighton R, Sands M (1965)...



Dapagliflozin suppresses glucagon signaling in rodent models of diabetes [Physiology]

2017-06-20T09:04:17-07:00

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a class of antidiabetic drug used for the treatment of diabetes. These drugs are thought to lower blood glucose by blocking reabsorption of glucose by SGLT2 in the proximal convoluted tubules of the kidney. To investigate the effect of inhibiting SGLT2 on pancreatic hormones,...



Phosphorylation and negative regulation of CONSTITUTIVELY PHOTOMORPHOGENIC 1 by PINOID in Arabidopsis [Plant Biology]

2017-06-20T09:04:17-07:00

CONSTITUTIVELY PHOTOMORPHOGENIC 1 (COP1) plays crucial roles in various cellular processes via its E3 ubiquitin ligase activity in organisms, ranging from fungi to humans. As a key component in regulating various biological events, COP1 itself is precisely controlled at multiple layers. Here, we report a negative regulator of COP1, PINOID...



Establishment of a vernalization requirement in Brachypodium distachyon requires REPRESSOR OF VERNALIZATION1 [Plant Biology]

2017-06-20T09:04:17-07:00

A requirement for vernalization, the process by which prolonged cold exposure provides competence to flower, is an important adaptation to temperate climates that ensures flowering does not occur before the onset of winter. In temperate grasses, vernalization results in the up-regulation of VERNALIZATION1 (VRN1) to establish competence to flower; however,...



Temperature variability is integrated by a spatially embedded decision-making center to break dormancy in Arabidopsis seeds [Plant Biology]

2017-06-20T09:04:17-07:00

Plants perceive and integrate information from the environment to time critical transitions in their life cycle. Some mechanisms underlying this quantitative signal processing have been described, whereas others await discovery. Seeds have evolved a mechanism to integrate environmental information by regulating the abundance of the antagonistically acting hormones abscisic acid...



Impact of International Monetary Fund programs on child health [Population Biology]

2017-06-20T09:04:16-07:00

Parental education is located at the center of global efforts to improve child health. In a developing-country context, the International Monetary Fund (IMF) plays a crucial role in determining how governments allocate scarce resources to education and public health interventions. Under reforms mandated by IMF structural adjustment programs, it may...



Dynamics of avian haemosporidian assemblages through millennial time scales inferred from insular biotas of the West Indies [Population Biology]

2017-06-20T09:04:17-07:00

Although introduced hemosporidian (malaria) parasites (Apicomplexa: Haemosporida) have hastened the extinction of endemic bird species in the Hawaiian Islands and perhaps elsewhere, little is known about the temporal dynamics of endemic malaria parasite populations. Haemosporidian parasites do not leave informative fossils, and records of population change are lacking beyond a...



Offspring of parents who were separated and not speaking to one another have reduced resistance to the common cold as adults [Psychological and Cognitive Sciences]

2017-06-20T09:04:16-07:00

Exposure to parental separation or divorce during childhood has been associated with an increased risk for physical morbidity during adulthood. Here we tested the hypothesis that this association is primarily attributable to separated parents who do not communicate with each other. We also examined whether early exposure to separated parents...



Language from police body camera footage shows racial disparities in officer respect [Psychological and Cognitive Sciences]

2017-06-20T09:04:16-07:00

Using footage from body-worn cameras, we analyze the respectfulness of police officer language toward white and black community members during routine traffic stops. We develop computational linguistic methods that extract levels of respect automatically from transcripts, informed by a thin-slicing study of participant ratings of officer utterances. We find that...



Secular rise in economically valuable personality traits [Psychological and Cognitive Sciences]

2017-06-20T09:04:16-07:00

Although trends in many physical characteristics and cognitive capabilities of modern humans are well-documented, less is known about how personality traits have evolved over time. We analyze data from a standardized personality test administered to 79% of Finnish men born between 1962 and 1976 (n = 419,523) and find steady...



Adaptive self-organization of Bali’s ancient rice terraces [Sustainability Science]

2017-06-20T09:04:16-07:00

Spatial patterning often occurs in ecosystems as a result of a self-organizing process caused by feedback between organisms and the physical environment. Here, we show that the spatial patterns observable in centuries-old Balinese rice terraces are also created by feedback between farmers’ decisions and the ecology of the paddies, which...



Ecosystem-based management and the wealth of ecosystems [Sustainability Science]

2017-06-20T09:04:16-07:00

We merge inclusive wealth theory with ecosystem-based management (EBM) to address two challenges in the science of sustainable management of ecosystems. First, we generalize natural capital theory to approximate realized shadow prices for multiple interacting natural capital stocks (species) making up an ecosystem. These prices enable ecosystem components to be...



In This Issue [This Week in PNAS]

2017-06-13T09:29:38-07:00

Metabolic adaptations of Sherpas to high altitudes Sherpa mountaineers in the Himalayas. Image courtesy of iStock/fotoVoyager. Previous studies have suggested that enhanced mechanisms for tissue oxygen delivery in Sherpas of Tibetan descent might play a role in their ability to survive at high altitude. However, whether metabolic adaptations that alter...



Profile of King-Wai Yau [Profiles]

2017-06-13T09:29:38-07:00

Neuroscientist King-Wai Yau of Johns Hopkins University has made fundamental discoveries concerning the mechanisms underlying sensory transduction. His research over the past four decades has focused primarily on vision. “Vision is one of our most precious senses from which come art, science, humanity, beauty, and practically all aspects of life,”...



Bam and Otu can regulate stem cell fate by stabilizing cyclin A [Developmental Biology]

2017-06-13T09:29:38-07:00

Identifying factors that regulate the balance between stem cell self-renewal and differentiation into specialized cells is key to understanding tissue homeostasis and regeneration. Long before the identification of the four factors sufficient to define stemness, a single gene named bag of marbles (bam) was shown to be necessary and sufficient...



Detection of sickness in conspecifics using olfactory and visual cues [Psychological and Cognitive Sciences]

2017-06-13T09:29:38-07:00

Social Communication in Humans Social communication in humans, although largely based on sophisticated language skills, is also substantially mediated by nonverbal cues that the receiver perceives through his/her senses. It is largely acknowledged that humans are highly visual organisms and that their perception of the social and physical environment is...



Ancestral gene regulatory networks drive cancer [Systems Biology]

2017-06-13T09:29:38-07:00

Although cancer is one of the most intensively studied phenomena in biology and occurs in almost all multicellular species (1, 2), an explanation for its existence and properties within the context of evolutionary history has received comparatively little attention. However, it is widely recognized that progress in treatment and prevention...



Electron localization in rod-shaped triicosahedral gold nanocluster [Chemistry]

2017-06-13T09:29:39-07:00

Atomically precise gold nanocluster based on linear assembly of repeating icosahedrons (clusters of clusters) is a unique type of linear nanostructure, which exhibits strong near-infrared absorption as their free electrons are confined in a one-dimensional quantum box. Little is known about the carrier dynamics in these nanoclusters, which limit their...



Hidden role of intermolecular proton transfer in the anomalously diffuse vibrational spectrum of a trapped hydronium ion [Chemistry]

2017-06-13T09:29:39-07:00

We report the vibrational spectra of the hydronium and methyl-ammonium ions captured in the C3v binding pocket of the 18-crown-6 ether ionophore. Although the NH stretching bands of the CH3NH3+ ion are consistent with harmonic expectations, the OH stretching bands of H3O+ are surprisingly broad, appearing as a diffuse background...



Myosin Va’s adaptor protein melanophilin enforces track selection on the microtubule and actin networks in vitro [Biochemistry]

2017-06-13T09:29:39-07:00

Pigment organelles, or melanosomes, are transported by kinesin, dynein, and myosin motors. As such, melanosome transport is an excellent model system to study the functional relationship between the microtubule- and actin-based transport systems. In mammalian melanocytes, it is well known that the Rab27a/melanophilin/myosin Va complex mediates actin-based transport in vivo....



Mechanistic insights on the reduction of glutathione disulfide by protein disulfide isomerase [Biophysics and Computational Biology]

2017-06-13T09:29:39-07:00

We explore the enzymatic mechanism of the reduction of glutathione disulfide (GSSG) by the reduced a domain of human protein disulfide isomerase (hPDI) with atomistic resolution. We use classical molecular dynamics and hybrid quantum mechanics/molecular mechanics calculations at the mPW1N/6–311+G(2d,2p):FF99SB//mPW1N/6–31G(d):FF99SB level. The reaction proceeds in two stages: (i) a thiol-disulfide...



Superresolution microscopy reveals the three-dimensional organization of meiotic chromosome axes in intact Caenorhabditis elegans tissue [Cell Biology]

2017-06-13T09:29:39-07:00

When cells enter meiosis, their chromosomes reorganize as linear arrays of chromatin loops anchored to a central axis. Meiotic chromosome axes form a platform for the assembly of the synaptonemal complex (SC) and play central roles in other meiotic processes, including homologous pairing, recombination, and chromosome segregation. However, little is...



Evidence for self-organization in determining spatial patterns of stream nutrients, despite primacy of the geomorphic template [Ecology]

2017-06-13T09:29:39-07:00

Nutrients in freshwater ecosystems are highly variable in space and time. Nevertheless, the variety of processes contributing to nutrient patchiness, and the wide range of spatial and temporal scales at which these processes operate, obfuscate how this spatial heterogeneity is generated. Here, we describe the spatial structure of stream nutrient...



RNA-seq reveals conservation of function among the yolk sacs of human, mouse, and chicken [Evolution]

2017-06-13T09:29:39-07:00

The yolk sac is phylogenetically the oldest of the extraembryonic membranes. The human embryo retains a yolk sac, which goes through primary and secondary phases of development, but its importance is controversial. Although it is known to synthesize proteins, its transport functions are widely considered vestigial. Here, we report RNA-sequencing...



Estimating the parameters of background selection and selective sweeps in Drosophila in the presence of gene conversion [Evolution]

2017-06-13T09:29:39-07:00

We used whole-genome resequencing data from a population of Drosophila melanogaster to investigate the causes of the negative correlation between the within-population synonymous nucleotide site diversity (πS) of a gene and its degree of divergence from related species at nonsynonymous nucleotide sites (KA). By using the estimated distributions of mutational...



Follistatin is critical for mouse uterine receptivity and decidualization [Genetics]

2017-06-13T09:29:39-07:00

Embryo implantation remains a significant challenge for assisted reproductive technology, with implantation failure occurring in ∼50% of in vitro fertilization attempts. Understanding the molecular mechanisms underlying uterine receptivity will enable the development of new interventions and biomarkers. TGFβ family signaling in the uterus is critical for establishing and maintaining pregnancy....



Manipulating DNA damage-response signaling for the treatment of immune-mediated diseases [Immunology and Inflammation]

2017-06-13T09:29:39-07:00

Antigen-activated lymphocytes undergo extraordinarily rapid cell division in the course of immune responses. We hypothesized that this unique aspect of lymphocyte biology leads to unusual genomic stress in recently antigen-activated lymphocytes and that targeted manipulation of DNA damage-response (DDR) signaling pathways would allow for selective therapeutic targeting of pathological T...



How an alloreactive T-cell receptor achieves peptide and MHC specificity [Immunology and Inflammation]

2017-06-13T09:29:39-07:00

T-cell receptor (TCR) allorecognition is often presumed to be relatively nonspecific, attributable to either a TCR focus on exposed major histocompatibility complex (MHC) polymorphisms or the degenerate recognition of allopeptides. However, paradoxically, alloreactivity can proceed with high peptide and MHC specificity. Although the underlying mechanisms remain unclear, the existence of...



Thermal combination therapies for local drug delivery by magnetic resonance-guided high-intensity focused ultrasound [Medical Sciences]

2017-06-13T09:29:39-07:00

Several thermal-therapy strategies such as thermal ablation, hyperthermia-triggered drug delivery from temperature-sensitive liposomes (TSLs), and combinations of the above were investigated in a rhabdomyosarcoma rat tumor model (n = 113). Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) was used as a noninvasive heating device with precise temperature control for image-guided drug...



Structure-guided evolution of antigenically distinct adeno-associated virus variants for immune evasion [Microbiology]

2017-06-13T09:29:39-07:00

Preexisting neutralizing antibodies (NAbs) against adeno-associated viruses (AAVs) pose a major, unresolved challenge that restricts patient enrollment in gene therapy clinical trials using recombinant AAV vectors. Structural studies suggest that despite a high degree of sequence variability, antibody recognition sites or antigenic hotspots on AAVs and other related parvoviruses might...



AraC-like transcriptional activator CuxR binds c-di-GMP by a PilZ-like mechanism to regulate extracellular polysaccharide production [Microbiology]

2017-06-13T09:29:39-07:00

Cyclic dimeric GMP (c-di-GMP) has emerged as a key regulatory player in the transition between planktonic and sedentary biofilm-associated bacterial lifestyles. It controls a multitude of processes including production of extracellular polysaccharides (EPSs). The PilZ domain, consisting of an N-terminal “RxxxR” motif and a β-barrel domain, represents a prototype c-di-GMP...



Rifamycin action on RNA polymerase in antibiotic-tolerant Mycobacterium tuberculosis results in differentially detectable populations [Microbiology]

2017-06-13T09:29:39-07:00

Mycobacterium tuberculosis (Mtb) encounters stresses during the pathogenesis and treatment of tuberculosis (TB) that can suppress replication of the bacteria and render them phenotypically tolerant to most available drugs. Where studied, the majority of Mtb in the sputum of most untreated subjects with active TB have been found to be...



Cortical neurons multiplex reward-related signals along with sensory and motor information [Neuroscience]

2017-06-13T09:29:39-07:00

Rewards are known to influence neural activity associated with both motor preparation and execution. This influence can be exerted directly upon the primary motor (M1) and somatosensory (S1) cortical areas via the projections from reward-sensitive dopaminergic neurons of the midbrain ventral tegmental areas. However, the neurophysiological manifestation of reward-related signals...



Input timing for spatial processing is precisely tuned via constant synaptic delays and myelination patterns in the auditory brainstem [Neuroscience]

2017-06-13T09:29:39-07:00

Precise timing of synaptic inputs is a fundamental principle of neural circuit processing. The temporal precision of postsynaptic input integration is known to vary with the computational requirements of a circuit, yet how the timing of action potentials is tuned presynaptically to match these processing demands is not well understood....



Contacts between the endoplasmic reticulum and other membranes in neurons [Neuroscience]

2017-06-13T09:29:39-07:00

Close appositions between the membrane of the endoplasmic reticulum (ER) and other intracellular membranes have important functions in cell physiology. These include lipid homeostasis, regulation of Ca2+ dynamics, and control of organelle biogenesis and dynamics. Although these membrane contacts have previously been observed in neurons, their distribution and abundance have...



The POTRA domains of Toc75 exhibit chaperone-like function to facilitate import into chloroplasts [Plant Biology]

2017-06-13T09:29:39-07:00

Protein trafficking across membranes is an essential function in cells; however, the exact mechanism for how this occurs is not well understood. In the endosymbionts, mitochondria and chloroplasts, the vast majority of proteins are synthesized in the cytoplasm as preproteins and then imported into the organelles via specialized machineries. In...



AP1G mediates vacuolar acidification during synergid-controlled pollen tube reception [Plant Biology]

2017-06-13T09:29:39-07:00

Double fertilization in angiosperms requires the delivery of immotile sperm through pollen tubes, which enter embryo sacs to initiate synergid degeneration and to discharge. This fascinating process, called pollen tube reception, involves extensive communications between pollen tubes and synergids, within which few intracellular regulators involved have been revealed. Here, we...



Auxin steers root cell expansion via apoplastic pH regulation in Arabidopsis thaliana [Plant Biology]

2017-06-13T09:29:39-07:00

Plant cells are embedded within cell walls, which provide structural integrity, but also spatially constrain cells, and must therefore be modified to allow cellular expansion. The long-standing acid growth theory postulates that auxin triggers apoplast acidification, thereby activating cell wall-loosening enzymes that enable cell expansion in shoots. Interestingly, this model...



Marine reserves can mitigate and promote adaptation to climate change [Environmental Sciences]

2017-06-13T09:29:38-07:00

Strong decreases in greenhouse gas emissions are required to meet the reduction trajectory resolved within the 2015 Paris Agreement. However, even these decreases will not avert serious stress and damage to life on Earth, and additional steps are needed to boost the resilience of ecosystems, safeguard their wildlife, and protect...



Assessing human weaning practices with calcium isotopes in tooth enamel [Anthropology]

2017-06-13T09:29:39-07:00

Weaning practices differ among great apes and likely diverged during the course of human evolution, but behavioral inference from the fossil record is hampered by a lack of unambiguous biomarkers. Here, we show that early-life dietary transitions are recorded in human deciduous tooth enamel as marked variations in Ca isotope...



Deformable and conformal silk hydrogel inverse opal [Applied Physical Sciences]

2017-06-13T09:29:38-07:00

Photonic crystals (PhCs) efficiently manipulate photons at the nanoscale. Applying these crystals to biological tissue that has been subjected to large deformation and humid environments can lead to fascinating bioapplications such as in vivo biosensors and artificial ocular prostheses. These applications require that these PhCs have mechanical durability, deformability, and...



Characterization of the scrambling domain of the TMEM16 family [Biochemistry]

2017-06-13T09:29:39-07:00

The TMEM16 protein family has 10 members, each of which carries 10 transmembrane segments. TMEM16A and 16B are Ca2+-activated Cl− channels. Several other members, including TMEM16F, promote phospholipid scrambling between the inner and outer leaflets of a cell membrane in response to intracellular Ca2+. However, the mechanism by which TMEM16...



Three classes of oxygen-dependent cyclase involved in chlorophyll and bacteriochlorophyll biosynthesis [Biochemistry]

2017-06-13T09:29:39-07:00

The biosynthesis of (bacterio)chlorophyll pigments is among the most productive biological pathways on Earth. Photosynthesis relies on these modified tetrapyrroles for the capture of solar radiation and its conversion to chemical energy. (Bacterio)chlorophylls have an isocyclic fifth ring, the formation of which has remained enigmatic for more than 60 y....



Photoactivation mechanism of a carotenoid-based photoreceptor [Biochemistry]

2017-06-13T09:29:39-07:00

Photoprotection is essential for efficient photosynthesis. Cyanobacteria have evolved a unique photoprotective mechanism mediated by a water-soluble carotenoid-based photoreceptor known as orange carotenoid protein (OCP). OCP undergoes large conformational changes in response to intense blue light, and the photoactivated OCP facilitates dissipation of excess energy via direct interaction with allophycocyanins...



Zinc-binding structure of a catalytic amyloid from solid-state NMR [Biophysics and Computational Biology]

2017-06-13T09:29:39-07:00

Throughout biology, amyloids are key structures in both functional proteins and the end product of pathologic protein misfolding. Amyloids might also represent an early precursor in the evolution of life because of their small molecular size and their ability to self-purify and catalyze chemical reactions. They also provide attractive backbones...



A mechanism for lipid binding to apoE and the role of intrinsically disordered regions coupled to domain-domain interactions [Biophysics and Computational Biology]

2017-06-13T09:29:39-07:00

Relative to the apolipoprotein E (apoE) E3 allele of the APOE gene, apoE4 strongly increases the risk for the development of late-onset Alzheimer’s disease. However, apoE4 differs from apoE3 by only a single amino acid at position 112, which is arginine in apoE4 and cysteine in apoE3. It remains unclear...



Structural basis for ligand binding to an enzyme by a conformational selection pathway [Biophysics and Computational Biology]

2017-06-13T09:29:39-07:00

Proteins can bind target molecules through either induced fit or conformational selection pathways. In the conformational selection model, a protein samples a scarcely populated high-energy state that resembles a target-bound conformation. In enzymatic catalysis, such high-energy states have been identified as crucial entities for activity and the dynamic interconversion between...



A helicase-independent activity of eIF4A in promoting mRNA recruitment to the human ribosome [Biophysics and Computational Biology]

2017-06-13T09:29:39-07:00

In the scanning model of translation initiation, the decoding site and latch of the 40S subunit must open to allow the recruitment and migration of messenger RNA (mRNA); however, the precise molecular details for how initiation factors regulate mRNA accommodation into the decoding site have not yet been elucidated. Eukaryotic...



Viral and cellular mRNA-specific activators harness PABP and eIF4G to promote translation initiation downstream of cap binding [Cell Biology]

2017-06-13T09:29:39-07:00

Regulation of mRNA translation is a major control point for gene expression and is critical for life. Of central importance is the complex between cap-bound eukaryotic initiation factor 4E (eIF4E), eIF4G, and poly(A) tail-binding protein (PABP) that circularizes mRNAs, promoting translation and stability. This complex is often targeted to regulate...



Unique aqueous Li-ion/sulfur chemistry with high energy density and reversibility [Chemistry]

2017-06-13T09:29:39-07:00

Leveraging the most recent success in expanding the electrochemical stability window of aqueous electrolytes, in this work we create a unique Li-ion/sulfur chemistry of both high energy density and safety. We show that in the superconcentrated aqueous electrolyte, lithiation of sulfur experiences phase change from a high-order polysulfide to low-order...



Bam-dependent deubiquitinase complex can disrupt germ-line stem cell maintenance by targeting cyclin A [Developmental Biology]

2017-06-13T09:29:39-07:00

Drosophila germ-line stem cells (GSCs) provide an excellent model to study the regulatory mechanisms of stem cells in vivo. Bag of marbles (bam) has been demonstrated to be necessary and sufficient to promote GSC and cystoblast differentiation. Despite extensive investigation of its regulation and genetic functions, the biochemical nature of...



Microlayer source of oxygenated volatile organic compounds in the summertime marine Arctic boundary layer [Earth, Atmospheric, and Planetary Sciences]

2017-06-13T09:29:39-07:00

Summertime Arctic shipboard observations of oxygenated volatile organic compounds (OVOCs) such as organic acids, key precursors of climatically active secondary organic aerosol (SOA), are consistent with a novel source of OVOCs to the marine boundary layer via chemistry at the sea surface microlayer. Although this source has been studied in...



The impact of Last Glacial climate variability in west-European loess revealed by radiocarbon dating of fossil earthworm granules [Earth, Atmospheric, and Planetary Sciences]

2017-06-13T09:29:39-07:00

The characterization of Last Glacial millennial-timescale warming phases, known as interstadials or Dansgaard–Oeschger events, requires precise chronologies for the study of paleoclimate records. On the European continent, such chronologies are only available for several Last Glacial pollen and rare speleothem archives principally located in the Mediterranean domain. Farther north, in...



Postglacial response of Arctic Ocean gas hydrates to climatic amelioration [Earth, Atmospheric, and Planetary Sciences]

2017-06-13T09:29:39-07:00

Seafloor methane release due to the thermal dissociation of gas hydrates is pervasive across the continental margins of the Arctic Ocean. Furthermore, there is increasing awareness that shallow hydrate-related methane seeps have appeared due to enhanced warming of Arctic Ocean bottom water during the last century. Although it has been...



Tropical cyclone activity enhanced by Sahara greening and reduced dust emissions during the African Humid Period [Earth, Atmospheric, and Planetary Sciences]

2017-06-13T09:29:39-07:00

Tropical cyclones (TCs) can have devastating socioeconomic impacts. Understanding the nature and causes of their variability is of paramount importance for society. However, historical records of TCs are too short to fully characterize such changes and paleo-sediment archives of Holocene TC activity are temporally and geographically sparse. Thus, it is...



Early 20th-century Arctic warming intensified by Pacific and Atlantic multidecadal variability [Earth, Atmospheric, and Planetary Sciences]

2017-06-13T09:29:39-07:00

With amplified warming and record sea ice loss, the Arctic is the canary of global warming. The historical Arctic warming is poorly understood, limiting our confidence in model projections. Specifically, Arctic surface air temperature increased rapidly over the early 20th century, at rates comparable to those of recent decades despite...



Economic development, flow of funds, and the equilibrium interaction of financial frictions [Economic Sciences]

2017-06-13T09:29:38-07:00

We use a variety of different datasets from Thailand to study not only the extremes of micro and macro variables but also within-country flow of funds and labor migration. We develop a general equilibrium model that encompasses regional variation in the type of financial friction and calibrate it to measured...