Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Maximum likelihood refinement for small datasets [Chemistry]
    [Jul 2015]

    The crystallographic reliability index Rcomplete is based on a method proposed more than two decades ago. Because its calculation is computationally expensive its use did not spread into the crystallographic community in favor of the cross-validation method known as Rfree. The importance of Rfree has grown beyond a pure validation...
    Categories: Journal Articles
  • MYBPC regulates postnatal myocyte cytokinesis [Developmental Biology]
    [Jul 2015]

    Homozygous cardiac myosin binding protein C-deficient (Mybpct/t) mice develop dramatic cardiac dilation shortly after birth; heart size increases almost twofold. We have investigated the mechanism of cardiac enlargement in these hearts. Throughout embryogenesis myocytes undergo cell division while maintaining the capacity to pump blood by rapidly disassembling and reforming myofibrillar...
    Categories: Journal Articles
  • Control of blood cell progenitor maintenance [Developmental Biology]
    [Jul 2015]

    The maintenance of stem or progenitor cell fate relies on intrinsic factors as well as local cues from the cellular microenvironment and systemic signaling. In the lymph gland, an hematopoietic organ in Drosophila larva, a group of cells called the Posterior Signaling Centre (PSC), whose specification depends on the EBF...
    Categories: Journal Articles
  • Ingredients for a habitable Earth [Earth, Atmospheric, and Planetary Sciences]
    [Jul 2015]

    We use the C/N ratio as a monitor of the delivery of key ingredients of life to nascent terrestrial worlds. Total elemental C and N contents, and their ratio, are examined for the interstellar medium, comets, chondritic meteorites, and terrestrial planets; we include an updated estimate for the bulk silicate...
    Categories: Journal Articles
  • Stochastic games with changing population size [Ecology]
    [Jul 2015]

    Frequency-dependent selection and demographic fluctuations play important roles in evolutionary and ecological processes. Under frequency-dependent selection, the average fitness of the population may increase or decrease based on interactions between individuals within the population. This should be reflected in fluctuations of the population size even in constant environments. Here, we...
    Categories: Journal Articles
  • Attaining strong and tough cellulose nanopaper [Engineering]
    [Jul 2015]

    The quest for both strength and toughness is perpetual in advanced material design; unfortunately, these two mechanical properties are generally mutually exclusive. So far there exists only limited success of attaining both strength and toughness, which often needs material-specific, complicated, or expensive synthesis processes and thus can hardly be applicable...
    Categories: Journal Articles
  • Postfire regeneration in South African fynbos [Environmental Sciences]
    [Jul 2015]

    Conservation of biodiversity and natural resources in a changing climate requires understanding what controls ecosystem resilience to disturbance. This understanding is especially important in the fire-prone Mediterranean systems of the world. The fire frequency in these systems is sensitive to climate, and recent climate change has resulted in more frequent...
    Categories: Journal Articles
  • Recombinant transfer in the E. coli basic genome [Evolution]
    [Jul 2015]

    An approximation to the ∼4-Mbp basic genome shared by 32 strains of Escherichia coli representing six evolutionary groups has been derived and analyzed computationally. A multiple alignment of the 32 complete genome sequences was filtered to remove mobile elements and identify the most reliable ∼90% of the aligned length of...
    Categories: Journal Articles
  • De novo evolution of kin discrimination [Evolution]
    [Jul 2015]

    Diverse forms of kin discrimination, broadly defined as alteration of social behavior as a function of genetic relatedness among interactants, are common among social organisms from microbes to humans. However, the evolutionary origins and causes of kin-discriminatory behavior remain largely obscure. One form of kin discrimination observed in microbes is...
    Categories: Journal Articles
  • Molecular basis for the STING/cGAMP recognition [Immunology and Inflammation]
    [Jul 2015]

    Cyclic GMP-AMP containing a unique combination of mixed phosphodiester linkages (2′3′-cGAMP) is an endogenous second messenger molecule that activates the type-I IFN pathway upon binding to the homodimer of the adaptor protein STING on the surface of endoplasmic reticulum membrane. However, the preferential binding of the asymmetric ligand 2′3′-cGAMP to...
    Categories: Journal Articles
  • ER stress drives pain [Medical Sciences]
    [Jul 2015]

    Despite intensive effort and resulting gains in understanding the mechanisms underlying neuropathic pain, limited success in therapeutic approaches have been attained. A recently identified, nonchannel, nonneurotransmitter therapeutic target for pain is the enzyme soluble epoxide hydrolase (sEH). The sEH degrades natural analgesic lipid mediators, epoxy fatty acids (EpFAs), therefore its...
    Categories: Journal Articles
  • ALDH2 suppresses liver tumors [Medical Sciences]
    [Jul 2015]

    Mitochondrial aldehyde dehydrogenase 2 (ALDH2) in the liver removes toxic aldehydes including acetaldehyde, an intermediate of ethanol metabolism. Nearly 40% of East Asians inherit an inactive ALDH2*2 variant, which has a lysine-for-glutamate substitution at position 487 (E487K), and show a characteristic alcohol flush reaction after drinking and a higher risk...
    Categories: Journal Articles
  • Influenza dynamics and control in households [Medical Sciences]
    [Jul 2015]

    Household-based interventions are the mainstay of public health policy against epidemic respiratory pathogens when vaccination is not available. Although the efficacy of these interventions has traditionally been measured by their ability to reduce the proportion of household contacts who exhibit symptoms [household secondary attack rate (hSAR)], this metric is difficult...
    Categories: Journal Articles
  • Promoter engineering of natural product clusters [Microbiology]
    [Jul 2015]

    Large-scale sequencing of prokaryotic (meta)genomic DNA suggests that most bacterial natural product gene clusters are not expressed under common laboratory culture conditions. Silent gene clusters represent a promising resource for natural product discovery and the development of a new generation of therapeutics. Unfortunately, the characterization of molecules encoded by these...
    Categories: Journal Articles
  • Unique dsRNA mycovirus from A. fumigatus [Microbiology]
    [Jul 2015]

    We report the discovery and characterization of a double-stranded RNA (dsRNA) mycovirus isolated from the human pathogenic fungus Aspergillus fumigatus, Aspergillus fumigatus tetramycovirus-1 (AfuTmV-1), which reveals several unique features not found previously in positive-strand RNA viruses, including the fact that it represents the first dsRNA (to our knowledge) that is...
    Categories: Journal Articles
  • Conserved chaperone to discover divergent effector [Microbiology]
    [Jul 2015]

    The type VI secretion system (T6SS) is a lethal weapon used by many bacteria to kill eukaryotic predators or prokaryotic competitors. Killing by the T6SS results from repetitive delivery of toxic effectors. Despite their importance in dictating bacterial fitness, systematic prediction of T6SS effectors remains challenging due to high effector...
    Categories: Journal Articles
  • V-ATPase controls the F1Fo-ATPase [Microbiology]
    [Jul 2015]

    Kinetoplastid parasites cause lethal diseases in humans and animals. The kinetoplast itself contains the mitochondrial genome, comprising a huge, complex DNA network that is also an important drug target. Isometamidium, for example, is a key veterinary drug that accumulates in the kinetoplast in African trypanosomes. Kinetoplast independence and isometamidium resistance...
    Categories: Journal Articles
  • Network endophenotypes of schizophrenia [Neuroscience]
    [Jul 2015]

    Schizophrenia is increasingly conceived as a disorder of brain network organization or dysconnectivity syndrome. Functional MRI (fMRI) networks in schizophrenia have been characterized by abnormally random topology. We tested the hypothesis that network randomization is an endophenotype of schizophrenia and therefore evident also in nonpsychotic relatives of patients. Head movement-corrected,...
    Categories: Journal Articles
  • Photodrive of magnetic bubbles [Physics]
    [Jul 2015]

    Precise control of magnetic domain walls continues to be a central topic in the field of spintronics to boost infotech, logic, and memory applications. One way is to drive the domain wall by current in metals. In insulators, the incoherent flow of phonons and magnons induced by the temperature gradient...
    Categories: Journal Articles
  • Myocardial MCU inhibition [Physiology]
    [Jul 2015]

    Myocardial mitochondrial Ca2+ entry enables physiological stress responses but in excess promotes injury and death. However, tissue-specific in vivo systems for testing the role of mitochondrial Ca2+ are lacking. We developed a mouse model with myocardial delimited transgenic expression of a dominant negative (DN) form of the mitochondrial Ca2+ uniporter...
    Categories: Journal Articles