Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Notch inhibition initiates mitotic HC generation [Developmental Biology]
    [Jan 2015]

    The activation of cochlear progenitor cells is a promising approach for hair cell (HC) regeneration and hearing recovery. The mechanisms underlying the initiation of proliferation of postnatal cochlear progenitor cells and their transdifferentiation to HCs remain to be determined. We show that Notch inhibition initiates proliferation of supporting cells (SCs)...
    Categories: Journal Articles
  • Carbon isotope composition of deep Earth [Earth, Atmospheric, and Planetary Sciences]
    [Jan 2015]

    The carbon budget and dynamics of the Earth’s interior, including the core, are currently very poorly understood. Diamond-bearing, mantle-derived rocks show a very well defined peak at δ13C ≈ −5 ± 3‰ with a very broad distribution to lower values (∼−40‰). The processes that have produced the wide δ13C distributions...
    Categories: Journal Articles
  • Effects of human activities on aerosol formation [Earth, Atmospheric, and Planetary Sciences]
    [Jan 2015]

    Secondary organic aerosol (SOA) constitutes a substantial fraction of fine particulate matter and has important impacts on climate and human health. The extent to which human activities alter SOA formation from biogenic emissions in the atmosphere is largely undetermined. Here, we present direct observational evidence on the magnitude of anthropogenic...
    Categories: Journal Articles
  • H5N1 viral and bird migration networks [Ecology]
    [Jan 2015]

    The spatial spread of the highly pathogenic avian influenza virus H5N1 and its long-term persistence in Asia have resulted in avian influenza panzootics and enormous economic losses in the poultry sector. However, an understanding of the regional long-distance transmission and seasonal patterns of the virus is still lacking. In this...
    Categories: Journal Articles
  • Sound financial decisions despite cognitive aging [Economic Sciences]
    [Jan 2015]

    Age-related deterioration in cognitive ability may compromise the ability of older adults to make major financial decisions. We explore whether knowledge and expertise accumulated from past decisions can offset cognitive decline to maintain decision quality over the life span. Using a unique dataset that combines measures of cognitive ability (fluid...
    Categories: Journal Articles
  • Transdermal DFO prevents diabetic ulcers [Engineering]
    [Jan 2015]

    There is a high mortality in patients with diabetes and severe pressure ulcers. For example, chronic pressure sores of the heels often lead to limb loss in diabetic patients. A major factor underlying this is reduced neovascularization caused by impaired activity of the transcription factor hypoxia inducible factor-1 alpha (HIF-1α)....
    Categories: Journal Articles
  • Organotypic microfluidics to study extravasation [Engineering]
    [Jan 2015]

    A key aspect of cancer metastases is the tendency for specific cancer cells to home to defined subsets of secondary organs. Despite these known tendencies, the underlying mechanisms remain poorly understood. Here we develop a microfluidic 3D in vitro model to analyze organ-specific human breast cancer cell extravasation into bone-...
    Categories: Journal Articles
  • Turing calculation of antibiotic resistance [Evolution]
    [Jan 2015]

    Bacteria can rapidly evolve resistance to antibiotics via the SOS response, a state of high-activity DNA repair and mutagenesis. We explore here the first steps of this evolution in the bacterium Escherichia coli. Induction of the SOS response by the genotoxic antibiotic ciprofloxacin changes the E. coli rod shape into...
    Categories: Journal Articles
  • Tipping points and environmental change [Evolution]
    [Jan 2015]

    In an era of rapid climate change, there is a pressing need to understand how organisms will cope with faster and less predictable variation in environmental conditions. Here we develop a unifying model that predicts evolutionary responses to environmentally driven fluctuating selection and use this theoretical framework to explore the...
    Categories: Journal Articles
  • Carnivorous leaves from Baltic amber [Evolution]
    [Jan 2015]

    The fossil record of carnivorous plants is very scarce and macrofossil evidence has been restricted to seeds of the extant aquatic genus Aldrovanda of the Droseraceae family. No case of carnivorous plant traps has so far been reported from the fossil record. Here, we present two angiosperm leaves enclosed in...
    Categories: Journal Articles
  • Interspecific genomic introgression in mice [Evolution]
    [Jan 2015]

    We report on a genome-wide scan for introgression between the house mouse (Mus musculus domesticus) and the Algerian mouse (Mus spretus), using samples from the ranges of sympatry and allopatry in Africa and Europe. Our analysis reveals wide variability in introgression signatures along the genomes, as well as across the...
    Categories: Journal Articles
  • Dipeptide-mediated peptide exchange on MHC class I [Immunology and Inflammation]
    [Jan 2015]

    Peptide ligand selection by MHC class I molecules, which occurs by iterative optimization, is the centerpiece of immunodominance in antiviral and antitumor immune responses. For its understanding, the molecular mechanisms of peptide binding and dissociation by class I molecules must be elucidated. To this end, we have investigated dipeptides that...
    Categories: Journal Articles
  • p73 isoforms have opposing roles in angiogenesis [Medical Sciences]
    [Jan 2015]

    The p53-family member TAp73 is known to function as a tumor suppressor and regulates genomic integrity, cellular proliferation, and apoptosis; however, its role in tumor angiogenesis is poorly understood. Here we demonstrate that TAp73 regulates tumor angiogenesis through repression of proangiogenic and proinflammatory cytokines. Importantly, loss of TAp73 results in...
    Categories: Journal Articles
  • p73 regulates HIF-1{alpha} [Medical Sciences]
    [Jan 2015]

    Tumor hypoxia and hypoxia-inducible factor 1 (HIF-1) activation are associated with cancer progression. Here, we demonstrate that the transcription factor TAp73 opposes HIF-1 activity through a nontranscriptional mechanism, thus affecting tumor angiogenesis. TAp73-deficient mice have an increased incidence of spontaneous and chemically induced tumors that also display enhanced vascularization. Mechanistically,...
    Categories: Journal Articles
  • BRD4 is a therapeutic target in ovarian cancer [Medical Sciences]
    [Jan 2015]

    High-grade serous ovarian carcinoma (HGSOC) is the most common and aggressive form of epithelial ovarian cancer, for which few targeted therapies exist. To search for new therapeutic target proteins, we performed an in vivo shRNA screen using an established human HGSOC cell line growing either subcutaneously or intraperitoneally in immunocompromised...
    Categories: Journal Articles
  • Influenza facilitated coinfection by TGF-{beta} [Microbiology]
    [Jan 2015]

    Influenza infection predisposes the host to secondary bacterial pneumonia, which is a major cause of mortality during influenza epidemics. The molecular mechanisms underlying the bacterial coinfection remain elusive. Neuraminidase (NA) of influenza A virus (IAV) enhances bacterial adherence and also activates TGF-β. Because TGF-β can up-regulate host adhesion molecules such...
    Categories: Journal Articles
  • Genomics and physiology of TM7 [Microbiology]
    [Jan 2015]

    The candidate phylum TM7 is globally distributed and often associated with human inflammatory mucosal diseases. Despite its prevalence, the TM7 phylum remains recalcitrant to cultivation, making it one of the most enigmatic phyla known. In this study, we cultivated a TM7 phylotype (TM7x) from the human oral cavity. This extremely...
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  • Adaptor-mediated proteolysis restricts swarming [Microbiology]
    [Jan 2015]

    The Lon AAA+ protease is a highly conserved intracellular protease that is considered an anticancer target in eukaryotic cells and a crucial virulence regulator in bacteria. Lon degrades both damaged, misfolded proteins and specific native regulators, but how Lon discriminates among a large pool of candidate targets remains unclear. Here...
    Categories: Journal Articles
  • Stress and VZV autophagic flux [Microbiology]
    [Jan 2015]

    Autophagy is a process by which misfolded and damaged proteins are sequestered into autophagosomes, before degradation in and recycling from lysosomes. We have extensively studied the role of autophagy in varicella-zoster virus (VZV) infection, and have observed that vesicular cells are filled with >100 autophagosomes that are easily detectable after...
    Categories: Journal Articles
  • TEM analysis of putative magnetoreceptors [Neuroscience]
    [Jan 2015]

    The cellular basis of the magnetic sense remains an unsolved scientific mystery. One theory that aims to explain how animals detect the magnetic field is the magnetite hypothesis. It argues that intracellular crystals of the iron oxide magnetite (Fe3O4) are coupled to mechanosensitive channels that elicit neuronal activity in specialized...
    Categories: Journal Articles