Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Commonness and rarity in the marine biosphere [Ecology]
    [Jun 2014]

    Explaining patterns of commonness and rarity is fundamental for understanding and managing biodiversity. Consequently, a key test of biodiversity theory has been how well ecological models reproduce empirical distributions of species abundances. However, ecological models with very different assumptions can predict similar species abundance distributions, whereas models with similar assumptions...
    Categories: Journal Articles
  • Multiscale observations at Four Corners [Environmental Sciences]
    [Jun 2014]

    There is a pressing need to verify air pollutant and greenhouse gas emissions from anthropogenic fossil energy sources to enforce current and future regulations. We demonstrate the feasibility of using simultaneous remote sensing observations of column abundances of CO2, CO, and NO2 to inform and verify emission inventories. We report,...
    Categories: Journal Articles
  • A forager-herder trade-off at A{#x015F}{#x0131}kl{#x0131} Hoyuk [Evolution]
    [Jun 2014]

    Aşıklı Höyük is the earliest known preceramic Neolithic mound site in Central Anatolia. The oldest Levels, 4 and 5, spanning 8,200 to approximately 9,000 cal B.C., associate with round-house architecture and arguably represent the birth of the Pre-Pottery Neolithic in the region. Results from upper Level 4, reported here, indicate...
    Categories: Journal Articles
  • Hedgehog signaling and cichlid feeding mechanics [Evolution]
    [Jun 2014]

    Adaptive variation in the craniofacial skeleton is a key component of resource specialization and habitat divergence in vertebrates, but the proximate genetic mechanisms that underlie complex patterns of craniofacial variation are largely unknown. Here we demonstrate that the Hedgehog (Hh) signaling pathway mediates widespread variation across a complex functional system...
    Categories: Journal Articles
  • Sequence and structural divergence of OSBS enzymes [Evolution]
    [Jun 2014]

    The rate of protein evolution is determined by a combination of selective pressure on protein function and biophysical constraints on protein folding and structure. Determining the relative contributions of these properties is an unsolved problem in molecular evolution with broad implications for protein engineering and function prediction. As a case...
    Categories: Journal Articles
  • ICK regulates ciliogenesis and Hedgehog signaling [Genetics]
    [Jun 2014]

    Endocrine-cerebro-osteodysplasia (ECO) syndrome is a recessive genetic disorder associated with multiple congenital defects in endocrine, cerebral, and skeletal systems that is caused by a missense mutation in the mitogen-activated protein kinase-like intestinal cell kinase (ICK) gene. In algae and invertebrates, ICK homologs are involved in flagellar formation and ciliogenesis, respectively....
    Categories: Journal Articles
  • Stress-induced transgenerational epigenetic memory [Genetics]
    [Jun 2014]

    Examples of transgenerational transmission of environmentally induced epigenetic traits remain rare and disputed. Abiotic stress can release the transcription of epigenetically suppressed transposons and, noticeably, this activation is only transient. Therefore, it is likely that mechanisms countering the mitotic and meiotic inheritance of stress-triggered chromatin changes must exist but are...
    Categories: Journal Articles
  • HLA-DP2 transgenic murine model of CBD [Immunology]
    [Jun 2014]

    Susceptibility to chronic beryllium disease (CBD) is linked to certain HLA-DP molecules, including HLA-DP2. To elucidate the molecular basis of this association, we exposed mice transgenic (Tg) for HLA-DP2 to beryllium oxide (BeO) via oropharyngeal aspiration. As opposed to WT mice, BeO-exposed HLA-DP2 Tg mice developed mononuclear infiltrates in a...
    Categories: Journal Articles
  • Dendritic cell survival clears chronic infection [Immunology]
    [Jun 2014]

    Chronic viral infections incapacitate adaptive immune responses by “exhausting” virus-specific T cells, inducing their deletion and reducing productive T-cell memory. Viral infection rapidly induces death receptor CD95 (Fas) expression by dendritic cells (DCs), making them susceptible to elimination by the immune response. Lymphocytic choriomeningitis virus (LCMV) clone 13, which normally...
    Categories: Journal Articles
  • Role of IL-15R{alpha} shedding in trans-presentation [Immunology]
    [Jun 2014]

    Interleukin (IL)-15 and its specific receptor chain, IL-15Rα, support the development of various effector cells, including NK and CD8 T cells via a mechanism called trans-presentation. Whereas the dynamic of trans-presentation has been shown to involve the recycling of IL-15Rα by presenting cells, the way responding cells integrate, or take...
    Categories: Journal Articles
  • Immunotoxins with silencing of T-cell epitopes [Medical Sciences]
    [Jun 2014]

    Nonhuman proteins have valuable therapeutic properties, but their efficacy is limited by neutralizing antibodies. Recombinant immunotoxins (RITs) are potent anticancer agents that have produced many complete remissions in leukemia, but immunogenicity limits the number of doses that can be given to patients with normal immune systems. Using human cells, we...
    Categories: Journal Articles
  • Size-based molecular diagnostics [Medical Sciences]
    [Jun 2014]

    Noninvasive prenatal testing using fetal DNA in maternal plasma is an actively researched area. The current generation of tests using massively parallel sequencing is based on counting plasma DNA sequences originating from different genomic regions. In this study, we explored a different approach that is based on the use of...
    Categories: Journal Articles
  • Genomic landscape of HSPCs in MDS [Medical Sciences]
    [Jun 2014]

    Myelodysplastic syndrome (MDS) includes a group of diseases characterized by dysplasia of bone marrow myeloid lineages with ineffective hematopoiesis and frequent evolution to acute myeloid leukemia (AML). Whole-genome sequencing was performed in CD34+ hematopoietic stem/progenitor cells (HSPCs) from eight cases of refractory anemia with excess blasts (RAEB), the high-risk subtype...
    Categories: Journal Articles
  • ERV-induced leukemia in PMF mouse model [Medical Sciences]
    [Jun 2014]

    The compound immunodeficiencies in nonobese diabetic (NOD) inbred mice homozygous for the Prkdcscid and Il2rgnull alleles (NSG mice) permit engraftment of a wide-range of primary human cells, enabling sophisticated modeling of human disease. In studies designed to define neoplastic stem cells of primary myelofibrosis (PMF), a myeloproliferative neoplasm characterized by...
    Categories: Journal Articles
  • Unitary stepping of the gliding bacteria [Microbiology]
    [Jun 2014]

    Among the bacteria that glide on substrate surfaces, Mycoplasma mobile is one of the fastest, exhibiting smooth movement with a speed of 2.0–4.5 μm⋅s−1 with a cycle of attachment to and detachment from sialylated oligosaccharides. To study the gliding mechanism at the molecular level, we applied an assay with a...
    Categories: Journal Articles
  • GABAA receptor target of TETS [Neuroscience]
    [Jun 2014]

    Use of the highly toxic and easily prepared rodenticide tetramethylenedisulfotetramine (TETS) was banned after thousands of accidental or intentional human poisonings, but it is of continued concern as a chemical threat agent. TETS is a noncompetitive blocker of the GABA type A receptor (GABAAR), but its molecular interaction has not...
    Categories: Journal Articles
  • Ontogenic heterogeneity of the subplate [Neuroscience]
    [Jun 2014]

    The subplate layer, the deepest cortical layer in mammals, has important roles in cerebral cortical development. The subplate contains heterogeneous cell populations that are morphologically diverse, with several projection targets. It is currently assumed that these cells are generated in the germinative zone of the earliest cortical neuroepithelium. Here we...
    Categories: Journal Articles
  • Predicting higher visual cortex neural responses [Neuroscience]
    [Jun 2014]

    The ventral visual stream underlies key human visual object recognition abilities. However, neural encoding in the higher areas of the ventral stream remains poorly understood. Here, we describe a modeling approach that yields a quantitatively accurate model of inferior temporal (IT) cortex, the highest ventral cortical area. Using high-throughput computational...
    Categories: Journal Articles
  • Local photic entrainment of the murine retina [Neuroscience]
    [Jun 2014]

    Synchronization of the mammalian master circadian pacemaker to the daily light/dark cycle is mediated exclusively through retinal photoreceptors. The mammalian retina itself is also a self-sustained circadian oscillator. Here we report that the retinal molecular circadian clock can be entrained by lighting cycles in vitro, but that rods, cones, and...
    Categories: Journal Articles
  • Cognitive flexibility and {beta}-catenin stabilization [Neuroscience]
    [Jun 2014]

    The cadherin/β-catenin adhesion complex is a key mediator of the bidirectional changes in synapse strength which are believed to underlie complex learning and memory. In the present study, we demonstrate that stabilization of β-catenin in the hippocampus of adult mice results in significant impairments in cognitive flexibility and spatial reversal...
    Categories: Journal Articles