Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Ultra-high-resolution lipid biomarker stratigraphy [Earth, Atmospheric, and Planetary Sciences]
    [Nov 2014]

    Marine microorganisms adapt to their habitat by structural modification of their membrane lipids. This concept is the basis of numerous molecular proxies used for paleoenvironmental reconstruction. Archaeal tetraether lipids from ubiquitous marine planktonic archaea are particularly abundant, well preserved in the sedimentary record and used in several molecular proxies. We...
    Categories: Journal Articles
  • Anammox enhancement by diel vertical migrations [Environmental Sciences]
    [Nov 2014]

    Measurements show that anaerobic ammonium oxidation with nitrite (anammox) is a major pathway of fixed nitrogen removal in the anoxic zones of the open ocean. Anammox requires a source of ammonium, which under anoxic conditions could be supplied by the breakdown of sinking organic matter via heterotrophic denitrification. However, at...
    Categories: Journal Articles
  • Mesophyll diffusion and CO2 fertilization on land [Environmental Sciences]
    [Nov 2014]

    In C3 plants, CO2 concentrations drop considerably along mesophyll diffusion pathways from substomatal cavities to chloroplasts where CO2 assimilation occurs. Global carbon cycle models have not explicitly represented this internal drawdown and therefore overestimate CO2 available for carboxylation and underestimate photosynthetic responsiveness to atmospheric CO2. An explicit consideration of mesophyll...
    Categories: Journal Articles
  • El Nino Southern Oscillation and global flood risk [Environmental Sciences]
    [Nov 2014]

    El Niño Southern Oscillation (ENSO) is the most dominant interannual signal of climate variability and has a strong influence on climate over large parts of the world. In turn, it strongly influences many natural hazards (such as hurricanes and droughts) and their resulting socioeconomic impacts, including economic damage and loss...
    Categories: Journal Articles
  • Disease-associated tolerance in transmitters [Immunology and Inflammation]
    [Nov 2014]

    Natural populations show striking heterogeneity in their ability to transmit disease. For example, a minority of infected individuals known as superspreaders carries out the majority of pathogen transmission events. In a mouse model of Salmonella infection, a subset of infected hosts becomes superspreaders, shedding high levels of bacteria (>108 cfu...
    Categories: Journal Articles
  • Diabetes and allostatic load [Medical Sciences]
    [Nov 2014]

    Psychological stress-related processes are thought to contribute to the development and progression of type 2 diabetes, but the biological mechanisms involved are poorly understood. Here, we tested the notion that people with type 2 diabetes experience chronic allostatic load, manifest as dynamic disturbances in reactivity to and recovery from stress...
    Categories: Journal Articles
  • Virioplankton ribonucleotide reductase [Microbiology]
    [Nov 2014]

    Virioplankton play a crucial role in aquatic ecosystems as top-down regulators of bacterial populations and agents of horizontal gene transfer and nutrient cycling. However, the biology and ecology of virioplankton populations in the environment remain poorly understood. Ribonucleotide reductases (RNRs) are ancient enzymes that reduce ribonucleotides to deoxyribonucleotides and thus...
    Categories: Journal Articles
  • NMR of Ran complexed with Mengo Leader protein [Microbiology]
    [Nov 2014]

    Cardiovirus Leader (L) proteins induce potent antihost inhibition of active cellular nucleocytoplasmic trafficking by triggering aberrant hyperphosphorylation of nuclear pore proteins (Nup). To achieve this, L binds protein RanGTPase (Ran), a key trafficking regulator, and diverts it into tertiary or quaternary complexes with required kinases. The activity of L is...
    Categories: Journal Articles
  • Recent H1N1 strains escape human antibodies [Microbiology]
    [Nov 2014]

    Influenza viruses typically cause the most severe disease in children and elderly individuals. However, H1N1 viruses disproportionately affected middle-aged adults during the 2013–2014 influenza season. Although H1N1 viruses recently acquired several mutations in the hemagglutinin (HA) glycoprotein, classic serological tests used by surveillance laboratories indicate that these mutations do not...
    Categories: Journal Articles
  • Rescue of dopamine by NSCs in PD rats [Neuroscience]
    [Nov 2014]

    Embryonic stem cell-based therapies exhibit great potential for the treatment of Parkinson’s disease (PD) because they can significantly rescue PD-like behaviors. However, whether the transplanted cells themselves release dopamine in vivo remains elusive. We and others have recently induced human embryonic stem cells into primitive neural stem cells (pNSCs) that...
    Categories: Journal Articles
  • Adiponectin, physical exercise, and neurogenesis [Neuroscience]
    [Nov 2014]

    Adiponectin (ADN) is an adipocyte-secreted protein with insulin-sensitizing, antidiabetic, antiinflammatory, and antiatherogenic properties. Evidence is also accumulating that ADN has neuroprotective activities, yet the underlying mechanism remains elusive. Here we show that ADN could pass through the blood–brain barrier, and elevating its levels in the brain increased cell proliferation and...
    Categories: Journal Articles
  • Drosophila TDP1 [Neuroscience]
    [Nov 2014]

    Tyrosyl-DNA phosphodiesterase (TDP1) is a phylogenetically conserved enzyme critical for the removal of blocking lesions at the 3′ ends of DNA or RNA. This study analyzes the Drosophila TDP1 gene ortholog glaikit (gkt) and its possible role(s) in the repair of endogenous DNA lesions and neuroprotection. To do so, we...
    Categories: Journal Articles
  • Up4A is a novel purine regulator in the colon [Neuroscience]
    [Nov 2014]

    Enteric purinergic motor neurotransmission, acting through P2Y1 receptors (P2Y1R), mediates inhibitory neural control of the intestines. Recent studies have shown that NAD+ and ADP ribose better meet criteria for enteric inhibitory neurotransmitters in colon than ATP or ADP. Here we report that human and murine colon muscles also release uridine...
    Categories: Journal Articles
  • Motive attribution asymmetry [Psychological and Cognitive Sciences]
    [Nov 2014]

    Five studies across cultures involving 661 American Democrats and Republicans, 995 Israelis, and 1,266 Palestinians provide previously unidentified evidence of a fundamental bias, what we term the “motive attribution asymmetry,” driving seemingly intractable human conflict. These studies show that in political and ethnoreligious intergroup conflict, adversaries tend to attribute their...
    Categories: Journal Articles
  • Learning regulatory programs by threshold SVD [Statistics]
    [Nov 2014]

    We formulate a statistical model for the regulation of global gene expression by multiple regulatory programs and propose a thresholding singular value decomposition (T-SVD) regression method for learning such a model from data. Extensive simulations demonstrate that this method offers improved computational speed and higher sensitivity and specificity over competing...
    Categories: Journal Articles
  • Harmonic mean and some applications [Statistics]
    [Nov 2014]

    Although the harmonic mean (HM) is mentioned in textbooks along with the arithmetic mean (AM) and the geometric mean (GM) as three possible ways of summarizing the information in a set of observations, its appropriateness in some statistical applications is not mentioned in textbooks. During the last 10 y a...
    Categories: Journal Articles
  • Quasiparticle [Core Concepts]
    [Nov 2014]

    Physicists have identified dozens of different subatomic species in the particle zoo, but most physical and chemical interactions arise from only three: the proton, the neutron, and the electron. There are a lot of those: solids and liquids contain on the order of 1024 particles per cubic centimeter. In February,...
    Categories: Journal Articles
  • Genetic assortative mating due to stratification [Social Sciences]
    [Oct 2014]

    Domingue et al. (1) use genome-wide SNPs to show in non-Hispanic US whites that spouses are genetically more similar than random pairs of individuals. We argue that, although this reported result is descriptively true, the spousal genetic similarity can be explained by assortment on shared ancestry (i.e., population stratification) and...
    Categories: Journal Articles
  • Interpreting GAM [Social Sciences]
    [Oct 2014]

    Abdellaoui et al. (1) question our (2) finding that spouses are more genetically similar than nonspouses because they believe that we are only measuring ethnically based social sorting indexed by population stratification and not genetic assortative mating (GAM). To address this possibility, we evaluated GAM among a racially homogeneous group,...
    Categories: Journal Articles
  • Iron oxides stimulate anaerobic methane oxidation [Earth, Atmospheric, and Planetary Sciences]
    [Oct 2014]

    Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with 13C-labeled methane showed...
    Categories: Journal Articles