Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Antagonism screen identifies a UppS inhibitor [Microbiology]
    [Sep 2015]

    Drug combinations are valuable tools for studying biological systems. Although much attention has been given to synergistic interactions in revealing connections between cellular processes, antagonistic interactions can also have tremendous value in elucidating genetic networks and mechanisms of drug action. Here, we exploit the power of antagonism in a high-throughput...
    Categories: Journal Articles
  • Social modification of antibiosis in Streptomyces [Microbiology]
    [Sep 2015]

    Despite their importance for humans, there is little consensus on the function of antibiotics in nature for the bacteria that produce them. Classical explanations suggest that bacteria use antibiotics as weapons to kill or inhibit competitors, whereas a recent alternative hypothesis states that antibiotics are signals that coordinate cooperative social...
    Categories: Journal Articles
  • Microbiota during pregnancy [Microbiology]
    [Sep 2015]

    Despite the critical role of the human microbiota in health, our understanding of microbiota compositional dynamics during and after pregnancy is incomplete. We conducted a case-control study of 49 pregnant women, 15 of whom delivered preterm. From 40 of these women, we analyzed bacterial taxonomic composition of 3,767 specimens collected...
    Categories: Journal Articles
  • Hippocampal representations of space and time [Neuroscience]
    [Sep 2015]

    Memory stretches over a lifetime. In controlled laboratory settings, the hippocampus and other medial temporal lobe brain structures have been shown to represent space and time on the scale of meters and seconds. It remains unclear whether the hippocampus also represents space and time over the longer scales necessary for...
    Categories: Journal Articles
  • Multiple working memory component networks [Neuroscience]
    [Sep 2015]

    Lateral prefrontal cortex (PFC) is regarded as the hub of the brain’s working memory (WM) system, but it remains unclear whether WM is supported by a single distributed network or multiple specialized network components in this region. To investigate this problem, we recorded from neurons in PFC while monkeys made...
    Categories: Journal Articles
  • Ammonium as a signal in brain energy metabolism [Neuroscience]
    [Sep 2015]

    Neural activity is accompanied by a transient mismatch between local glucose and oxygen metabolism, a phenomenon of physiological and pathophysiological importance termed aerobic glycolysis. Previous studies have proposed glutamate and K+ as the neuronal signals that trigger aerobic glycolysis in astrocytes. Here we used a panel of genetically encoded FRET...
    Categories: Journal Articles
  • NMDARs control hippocampal-PFC transmission [Neuroscience]
    [Sep 2015]

    Functional connectivity between the hippocampus and prefrontal cortex (PFC) is essential for associative recognition memory and working memory. Disruption of hippocampal–PFC synchrony occurs in schizophrenia, which is characterized by hypofunction of NMDA receptor (NMDAR)-mediated transmission. We demonstrate that activity of dopamine D2-like receptors (D2Rs) leads selectively to long-term depression (LTD)...
    Categories: Journal Articles
  • Origin of colossal magnetoresistance in LaMnO3 [Physics]
    [Sep 2015]

    Phase separation is a crucial ingredient of the physics of manganites; however, the role of mixed phases in the development of the colossal magnetoresistance (CMR) phenomenon still needs to be clarified. We report the realization of CMR in a single-valent LaMnO3 manganite. We found that the insulator-to-metal transition at 32...
    Categories: Journal Articles
  • Two-dimensional defects in amorphous materials [Physics]
    [Sep 2015]

    We study the geometry of defects in amorphous materials and their elastic interactions. Defects are defined and characterized by deviations of the material’s intrinsic metric from a Euclidian metric. This characterization makes possible the identification of localized defects in amorphous materials, the formulation of a corresponding elastic problem, and its...
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  • Topological Bloch bands in graphene superlattices [Physics]
    [Sep 2015]

    We outline a designer approach to endow widely available plain materials with topological properties by stacking them atop other nontopological materials. The approach is illustrated with a model system comprising graphene stacked atop hexagonal boron nitride. In this case, the Berry curvature of the electron Bloch bands is highly sensitive...
    Categories: Journal Articles
  • Big Grain1 regulates auxin transport [Plant Biology]
    [Sep 2015]

    Grain size is one of the key factors determining grain yield. However, it remains largely unknown how grain size is regulated by developmental signals. Here, we report the identification and characterization of a dominant mutant big grain1 (Bg1-D) that shows an extra-large grain phenotype from our rice T-DNA insertion population....
    Categories: Journal Articles
  • SUMOylation modulates phytochrome signaling [Plant Biology]
    [Sep 2015]

    The red/far red light absorbing photoreceptor phytochrome-B (phyB) cycles between the biologically inactive (Pr, λmax, 660 nm) and active (Pfr; λmax, 730 nm) forms and functions as a light quality and quantity controlled switch to regulate photomorphogenesis in Arabidopsis. At the molecular level, phyB interacts in a conformation-dependent fashion with...
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  • Seasonal population fluxes and rubella dynamics [Population Biology]
    [Sep 2015]

    Changing patterns of human aggregation are thought to drive annual and multiannual outbreaks of infectious diseases, but the paucity of data about travel behavior and population flux over time has made this idea difficult to test quantitatively. Current measures of human mobility, especially in low-income settings, are often static, relying...
    Categories: Journal Articles
  • Parietal dynamics during recognition memory [Psychological and Cognitive Sciences]
    [Sep 2015]

    Theories of the neurobiology of episodic memory predominantly focus on the contributions of medial temporal lobe structures, based on extensive lesion, electrophysiological, and imaging evidence. Against this backdrop, functional neuroimaging data have unexpectedly implicated left posterior parietal cortex (PPC) in episodic retrieval, revealing distinct activation patterns in PPC subregions as...
    Categories: Journal Articles
  • Mental orientation in space, time, and person [Psychological and Cognitive Sciences]
    [Sep 2015]

    Orientation is a fundamental mental function that processes the relations between the behaving self to space (places), time (events), and person (people). Behavioral and neuroimaging studies have hinted at interrelations between processing of these three domains. To unravel the neurocognitive basis of orientation, we used high-resolution 7T functional MRI as...
    Categories: Journal Articles
  • State of the Union [Social Sciences]
    [Sep 2015]

    This study reveals that the entry into World War I in 1917 indexed the decisive transition to the modern period in American political consciousness, ushering in new objects of political discourse, a more rapid pace of change of those objects, and a fundamental reframing of the main tasks of governance....
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  • Comanaging conservation and food safety [Sustainability Science]
    [Sep 2015]

    In 2006, a deadly Escherichia coli O157:H7 outbreak in bagged spinach was traced to California’s Central Coast region, where >70% of the salad vegetables sold in the United States are produced. Although no definitive cause for the outbreak could be determined, wildlife was implicated as a disease vector. Growers were...
    Categories: Journal Articles
  • Confronting conservation values [Sustainability Science]
    [Sep 2015]

    Diverse motivations for preserving nature both inspire and hinder its conservation. Optimal conservation strategies may differ radically depending on the objective. For example, creating nature reserves may prevent extinctions through protecting severely threatened species, whereas incentivizing farmland hedgerows may benefit people through bolstering pest-eating or pollinating species. Win-win interventions that...
    Categories: Journal Articles
  • Electricity dispatching with health considerations [Sustainability Science]
    [Sep 2015]

    Integrating accurate air quality modeling with decision making is hampered by complex atmospheric physics and chemistry and its coupling with atmospheric transport. Existing approaches to model the physics and chemistry accurately lead to significant computational burdens in computing the response of atmospheric concentrations to changes in emissions profiles. By integrating...
    Categories: Journal Articles
  • Social dynamics and ecological regime shifts [Sustainability Science]
    [Sep 2015]

    Regime shifts triggered by human activities and environmental changes have led to significant ecological and socioeconomic consequences in marine and terrestrial ecosystems worldwide. Ecological processes and feedbacks associated with regime shifts have received considerable attention, but human individual and collective behavior is rarely treated as an integrated component of such...
    Categories: Journal Articles