Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • 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
  • ABCA4 retinoid transport activity [Neuroscience]
    [Apr 2014]

    The visual cycle is a series of enzyme-catalyzed reactions which converts all-trans-retinal to 11-cis-retinal for the regeneration of visual pigments in rod and cone photoreceptor cells. Although essential for vision, 11-cis-retinal like all-trans-retinal is highly toxic due to its highly reactive aldehyde group and has to be detoxified by either...
    Categories: Journal Articles
  • Vesicular codelivery of AMPARs and N-cadherin [Neuroscience]
    [Apr 2014]

    The GluA2 subunit of AMPA-type glutamate receptors (AMPARs) regulates excitatory synaptic transmission in neurons. In addition, the transsynaptic cell adhesion molecule N-cadherin controls excitatory synapse function and stabilizes dendritic spine structures. At postsynaptic membranes, GluA2 physically binds N-cadherin, underlying spine growth and synaptic modulation. We report that N-cadherin binds to...
    Categories: Journal Articles
  • PDE4A loss puts aging PFC at risk for degeneration [Neuroscience]
    [Apr 2014]

    The pattern of neurodegeneration in Alzheimer’s disease (AD) is very distinctive: neurofibrillary tangles (NFTs) composed of hyperphosphorylated tau selectively affect pyramidal neurons of the aging association cortex that interconnect extensively through glutamate synapses on dendritic spines. In contrast, primary sensory cortices have few NFTs, even in late-stage disease. Understanding this...
    Categories: Journal Articles
  • EphA7 signaling in cortical dendritic maturation [Physics]
    [Apr 2014]

    The process by which excitatory neurons are generated and mature during the development of the cerebral cortex occurs in a stereotyped manner; coordinated neuronal birth, migration, and differentiation during embryonic and early postnatal life are prerequisites for selective synaptic connections that mediate meaningful neurotransmission in maturity. Normal cortical function depends...
    Categories: Journal Articles
  • In vivo thylakoid remodeling by state transitions [Plant Biology]
    [Apr 2014]

    Plants respond to changes in light quality by regulating the absorption capacity of their photosystems. These short-term adaptations use redox-controlled, reversible phosphorylation of the light-harvesting complexes (LHCIIs) to regulate the relative absorption cross-section of the two photosystems (PSs), commonly referred to as state transitions. It is acknowledged that state transitions...
    Categories: Journal Articles