Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • GdmCl unfolds protein by a two-stage mechanism [Chemistry]
    [Apr 2014]

    Dry molten globular (DMG) intermediates, an expanded form of the native protein with a dry core, have been observed during denaturant-induced unfolding of many proteins. These observations are counterintuitive because traditional models of chemical denaturation rely on changes in solvent-accessible surface area, and there is no notable change in solvent-accessible...
    Categories: Journal Articles
  • ARF1-Asri{#x0237} axis controls blood cell homeostasis [Developmental Biology]
    [Apr 2014]

    Drosophila melanogaster larval hematopoiesis is a well-established model to study mechanisms that regulate hematopoietic niche maintenance and control of blood cell precursor (prohemocyte) differentiation. Molecules that perturb niche function affect the balance between prohemocytes and differentiated hemocytes. The conserved hemocyte-specific endosomal protein Asrij is essential for niche function and prohemocyte...
    Categories: Journal Articles
  • Tackling soil diversity with the assembly [Ecology]
    [Apr 2014]

    The large volumes of sequencing data required to sample deeply the microbial communities of complex environments pose new challenges to sequence analysis. De novo metagenomic assembly effectively reduces the total amount of data to be analyzed but requires substantial computational resources. We combine two preassembly filtering approaches—digital normalization and partitioning—to...
    Categories: Journal Articles
  • Large carbon uptake by East Asian monsoon forests [Ecology]
    [Apr 2014]

    Temperate- and high-latitude forests have been shown to contribute a carbon sink in the Northern Hemisphere, but fewer studies have addressed the carbon balance of the subtropical forests. In the present study, we integrated eddy covariance observations established in the 1990s and 2000s to show that East Asian monsoon subtropical...
    Categories: Journal Articles
  • Phenological shifts reshape a plant community [Ecology]
    [Apr 2014]

    Phenology—the timing of biological events—is highly sensitive to climate change. However, our general understanding of how phenology responds to climate change is based almost solely on incomplete assessments of phenology (such as first date of flowering) rather than on entire phenological distributions. Using a uniquely comprehensive 39-y flowering phenology dataset...
    Categories: Journal Articles
  • Moa were not in decline before human colonization [Genetics]
    [Apr 2014]

    The extinction of New Zealand's moa (Aves: Dinornithiformes) followed the arrival of humans in the late 13th century and was the final event of the prehistoric Late Quaternary megafauna extinctions. Determining the state of the moa populations in the pre-extinction period is fundamental to understanding the causes of the event....
    Categories: Journal Articles
  • Dynamics of vaccine-induced immune responses [Immunology]
    [Apr 2014]

    The adaptive immune system confers protection by generating a diverse repertoire of antibody receptors that are rapidly expanded and contracted in response to specific targets. Next-generation DNA sequencing now provides the opportunity to survey this complex and vast repertoire. In the present work, we describe a set of tools for...
    Categories: Journal Articles
  • GBA2 and Gaucher disease [Medical Sciences]
    [Apr 2014]

    The inherited deficiency of the lysosomal glucocerebrosidase (GBA) due to mutations in the GBA gene results in Gaucher disease (GD). A vast majority of patients present with nonneuronopathic, type 1 GD (GD1). GBA deficiency causes the accumulation of two key sphingolipids, glucosylceramide (GL-1) and glucosylsphingosine (LysoGL-1), classically noted within the...
    Categories: Journal Articles
  • Glycotoxins link dementia and metabolic syndrome [Medical Sciences]
    [Apr 2014]

    Age-associated dementia and Alzheimer’s disease (AD) are currently epidemic. Neither their cause nor connection to the metabolic syndrome (MS) is clear. Suppression of deacetylase survival factor sirtuin 1 (SIRT1), a key host defense, is a central feature of AD. Age-related MS and diabetes are also causally associated with suppressed SIRT1...
    Categories: Journal Articles
  • STAT3 interrupts ATR-Chk1 signaling [Medical Sciences]
    [Apr 2014]

    DNA damage response (DDR) is a signaling network that senses DNA damage and activates response pathways to coordinate cell-cycle progression and DNA repair. Thus, DDR is critical for maintenance of genome stability, and presents a powerful defense against tumorigenesis. Therefore, to drive cell-proliferation and transformation, viral and cellular oncogenes need...
    Categories: Journal Articles
  • Cell-of-origin of non-small-cell lung cancer [Medical Sciences]
    [Apr 2014]

    Much controversy surrounds the cell-of-origin of mutant K-Ras (K-RasG12D)–induced lung adenocarcinoma. To shed light on this issue, we have used technology that enables us to conditionally target K-RasG12D expression in Surfactant Protein C (SPC)+ alveolar type 2 cells and in Clara cell antigen 10 (CC10)+ Clara cells by use of...
    Categories: Journal Articles
  • Composition of mycobacterial outer membrane [Microbiology]
    [Apr 2014]

    Mycobacterium species, including the human pathogen Mycobacterium tuberculosis, are unique among Gram-positive bacteria in producing a complex cell wall that contains unusual lipids and functions as a permeability barrier. Lipids in the cell wall were hypothesized to form a bilayer or outer membrane that would prevent the entry of chemotherapeutic...
    Categories: Journal Articles
  • Reprogrammed intestinal microbiota in TMF-/- mice [Microbiology]
    [Apr 2014]

    Tata Element Modulatory Factor (TMF/ARA160) is a multifunctional Golgi-associated protein, which accumulates in colonic enterocytes and goblet cells. Mice lacking TMF/ARA160 (TMF−/−) produce thick and uniform colonic mucus that resists adherent bacterial colonization and diminishes susceptibility of these mice to induced acute colitis, through a mechanism that is not fully...
    Categories: Journal Articles
  • Generation of MERS-CoV mouse model [Microbiology]
    [Apr 2014]

    In this era of continued emergence of zoonotic virus infections, the rapid development of rodent models represents a critical barrier to public health preparedness, including the testing of antivirus therapy and vaccines. The Middle East respiratory syndrome coronavirus (MERS-CoV) was recently identified as the causative agent of a severe pneumonia....
    Categories: Journal Articles
  • Metabolic essentiality of the methylcitrate cycle [Microbiology]
    [Apr 2014]

    Few mutations attenuate Mycobacterium tuberculosis (Mtb) more profoundly than deletion of its isocitrate lyases (ICLs). However, the basis for this attenuation remains incompletely defined. Mtb’s ICLs are catalytically bifunctional isocitrate and methylisocitrate lyases required for growth on even and odd chain fatty acids. Here, we report that Mtb’s ICLs are...
    Categories: Journal Articles
  • Decoupling ATPase activity from LPS transport [Microbiology]
    [Apr 2014]

    The cell surface of Gram-negative bacteria contains lipopolysaccharides (LPS), which provide a barrier against the entry of many antibiotics. LPS assembly involves a multiprotein LPS transport (Lpt) complex that spans from the cytoplasm to the outer membrane. In this complex, an unusual ATP-binding cassette transporter is thought to power the...
    Categories: Journal Articles
  • Evolution of drug-resistant Klebsiella pneumoniae [Microbiology]
    [Apr 2014]

    Infections caused by drug-resistant bacteria are a major problem worldwide. Carbapenem-resistant Klebsiella pneumoniae, most notably isolates classified as multilocus sequence type (ST) 258, have emerged as an important cause of hospital deaths. ST258 isolates are predominantly multidrug resistant, and therefore infections caused by them are difficult to treat. It is...
    Categories: Journal Articles
  • Selective attention in the honeybee optic lobes [Neuroscience]
    [Apr 2014]

    Attention allows animals to respond selectively to competing stimuli, enabling some stimuli to evoke a behavioral response while others are ignored. How the brain does this remains mysterious, although it is increasingly evident that even animals with the smallest brains display this capacity. For example, insects respond selectively to salient...
    Categories: Journal Articles
  • Attribution of awareness [Neuroscience]
    [Apr 2014]

    This study tested the possible relationship between reported visual awareness (“I see a visual stimulus in front of me”) and the social attribution of awareness to someone else (“That person is aware of an object next to him”). Subjects were tested in two steps. First, in an fMRI experiment, subjects...
    Categories: Journal Articles
  • Lithium dually regulates GIRK channels [Neuroscience]
    [Apr 2014]

    Lithium (Li+) is widely used to treat bipolar disorder (BPD). Cellular targets of Li+, such as glycogen synthase kinase 3β (GSK3β) and G proteins, have long been implicated in BPD etiology; however, recent genetic studies link BPD to other proteins, particularly ion channels. Li+ affects neuronal excitability, but the underlying...
    Categories: Journal Articles