Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Transcription factor binding gets more complex [Biochemistry]
    [Dec 2014]

    In PNAS, Afek et al. (1) show that the specific (or “consensus”) base-pair sequences of a regulatory DNA target are not solely responsible for controlling the binding affinities of several eukaryotic transcription factors (TFs) for their DNA target sites. Rather, so-called “nonconsensus” sequences that flank the specific target, particularly flanking...
    Categories: Journal Articles
  • Complexity from precipitation reactions [Applied Physical Sciences]
    [Dec 2014]

    A key challenge for modern molecular sciences is to bridge the gap between the nanoscopic world and macroscopic devices. The underlying question is whether one can control chemical reactions to produce directly macroscopic complexity, hierarchical order, and ultimately entirely new types of materials. If viewed as a form of complicated...
    Categories: Journal Articles
  • Innate sense of purpose for IKK{beta} [Biochemistry]
    [Dec 2014]

    The innate immune response is initiated upon recognition of pathogen-associated molecular patterns (PAMPs) by germ-line encoded pattern-recognition receptors (PRRs). PRRs including transmembrane receptors, typified by the Toll-like receptors (TLR) and cytoplasmic receptors, including the RIG-I–like receptors (RLRs), trigger signal transduction cascades culminating in the activation of transcription factors that regulate...
    Categories: Journal Articles
  • Promiscuity of MAGUKs no more [Biochemistry]
    [Dec 2014]

    Membrane-associated guanylate kinases (MAGUKs) constitute a family of scaffold molecules involved in diverse cellular processes, such as cell–cell communication, cell polarity, and signal transduction (1). MAGUKs are multidomain proteins with a core structure consisting of PSD-95/DLG/ZO-1 (PDZ), Src homolgy 3 (SH3), and enzymatically inactive guanylate kinase (GK) domains. Although full-length...
    Categories: Journal Articles
  • Bioalcohol production by a synthetic route [Microbiology]
    [Dec 2014]

    The still growing demand for bioethanol is currently met by two microbiological processes. The by far most important process is the use of first- (sugar) or second- (lignocellulosic biomass) generation raw materials and yeast as catalysts. Yeasts convert the sugars via glycolysis to pyruvate, which is decarboxylated, and the resulting...
    Categories: Journal Articles
  • Dealing with femtorisks in international relations [Social Sciences]
    [Dec 2014]

    The contemporary global community is increasingly interdependent and confronted with systemic risks posed by the actions and interactions of actors existing beneath the level of formal institutions, often operating outside effective governance structures. Frequently, these actors are human agents, such as rogue traders or aggressive financial innovators, terrorists, groups of...
    Categories: Journal Articles
  • Confined chemical gardens [Applied Physical Sciences]
    [Dec 2014]

    Chemical gardens are mineral aggregates that grow in three dimensions with plant-like forms and share properties with self-assembled structures like nanoscale tubes, brinicles, or chimneys at hydrothermal vents. The analysis of their shapes remains a challenge, as their growth is influenced by osmosis, buoyancy, and reaction–diffusion processes. Here we show...
    Categories: Journal Articles
  • Prefreezing at the interface melt-solid [Applied Physical Sciences]
    [Dec 2014]

    Crystallization is almost always initiated at an interface to a solid. This observation is classically explained by the assumption of a reduced barrier for crystal nucleation at the interface. However, an interface can also induce crystallization by prefreezing (i.e., the formation of a crystalline layer that is already stable above...
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  • DNA looping mechanics modulates kinetics [Biophysics and Computational Biology]
    [Dec 2014]

    Storage and retrieval of the genetic information in cells is a dynamic process that requires the DNA to undergo dramatic structural rearrangements. DNA looping is a prominent example of such a structural rearrangement that is essential for transcriptional regulation in both prokaryotes and eukaryotes, and the speed of such regulations...
    Categories: Journal Articles
  • Emission seasonality of HCFC-22 and HFC-134a [Earth, Atmospheric, and Planetary Sciences]
    [Dec 2014]

    HCFC-22 (CHClF2) and HFC-134a (CH2FCF3) are two major gases currently used worldwide in domestic and commercial refrigeration and air conditioning. HCFC-22 contributes to stratospheric ozone depletion, and both species are potent greenhouse gases. In this work, we study in situ observations of HCFC-22 and HFC-134a taken from research aircraft over...
    Categories: Journal Articles
  • Remote-controlled therapy with resorbable devices [Engineering]
    [Dec 2014]

    A paradigm shift for implantable medical devices lies at the confluence between regenerative medicine, where materials remodel and integrate in the biological milieu, and technology, through the use of recently developed material platforms based on biomaterials and bioresorbable technologies such as optics and electronics. The union of materials and technology...
    Categories: Journal Articles
  • Engineering material structure by fractal cut [Engineering]
    [Dec 2014]

    In this paper we discuss the transformation of a sheet of material into a wide range of desired shapes and patterns by introducing a set of simple cuts in a multilevel hierarchy with different motifs. Each choice of hierarchical cut motif and cut level allows the material to expand into...
    Categories: Journal Articles
  • Haze in China [Environmental Sciences]
    [Dec 2014]

    As the world’s second largest economy, China has experienced severe haze pollution, with fine particulate matter (PM) recently reaching unprecedentedly high levels across many cities, and an understanding of the PM formation mechanism is critical in the development of efficient mediation policies to minimize its regional to global impacts. We...
    Categories: Journal Articles
  • Isotope effect in the glass transition of water [Physics]
    [Dec 2014]

    We present the discovery of an unusually large isotope effect in the structural relaxation and the glass transition temperature Tg of water. Dielectric relaxation spectroscopy of low-density as well as of vapor-deposited amorphous water reveal Tg differences of 10 ± 2 K between H2O and D2O, sharply contrasting with other...
    Categories: Journal Articles
  • Generalized Metropolis-Hastings algorithm [Statistics]
    [Dec 2014]

    Markov chain Monte Carlo methods (MCMC) are essential tools for solving many modern-day statistical and computational problems; however, a major limitation is the inherently sequential nature of these algorithms. In this paper, we propose a natural generalization of the Metropolis−Hastings algorithm that allows for parallelizing a single chain using existing...
    Categories: Journal Articles
  • Animals that self-medicate [News Feature]
    [Dec 2014]

    Many animal species have created their own pharmacies from ingredients that commonly occur in nature. Birds, bees, lizards, elephants, and chimpanzees all share a survival trait: They self-medicate. These animals eat things that make them feel better, or prevent disease, or kill parasites like flatworms, bacteria, and viruses, or just...
    Categories: Journal Articles
  • Role of COQ9 in coenzyme Q biosynthesis [Biochemistry]
    [Nov 2014]

    Coenzyme Q (CoQ) is an isoprenylated quinone that is essential for cellular respiration and is synthesized in mitochondria by the combined action of at least nine proteins (COQ1–9). Although most COQ proteins are known to catalyze modifications to CoQ precursors, the biochemical role of COQ9 remains unclear. Here, we report...
    Categories: Journal Articles
  • NAADP/TPC2/Ca2+ in VEGF-induced angiogenesis [Cell Biology]
    [Nov 2014]

    Vascular endothelial growth factor (VEGF) and its receptors VEGFR1/VEGFR2 play major roles in controlling angiogenesis, including vascularization of solid tumors. Here we describe a specific Ca2+ signaling pathway linked to the VEGFR2 receptor subtype, controlling the critical angiogenic responses of endothelial cells (ECs) to VEGF. Key steps of this pathway...
    Categories: Journal Articles
  • WWOX regulates DDR [Cell Biology]
    [Nov 2014]

    Genomic instability is a hallmark of cancer. The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor spanning the common chromosomal fragile site FRA16D. Here, we report a direct role of WWOX in DNA damage response (DDR) and DNA repair. We show that Wwox deficiency results in reduced activation of the...
    Categories: Journal Articles
  • Single-cell transcriptional heterogeneity [Cell Biology]
    [Nov 2014]

    The acute cellular response to stress generates a subpopulation of reversibly stress-tolerant cells under conditions that are lethal to the majority of the population. Stress tolerance is attributed to heterogeneity of gene expression within the population to ensure survival of a minority. We performed whole transcriptome sequencing analyses of metastatic...
    Categories: Journal Articles