Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • LB1 discovery as a rare event in earth history [Evolution]
    [Aug 2014]

    The original centrally defining features of “Homo floresiensis” are based on bones represented only in the single specimen LB1. Initial published values of 380-mL endocranial volume and 1.06-m stature are markedly lower than later attempts to confirm them, and facial asymmetry originally unreported, then denied, has been established by our...
    Categories: Journal Articles
  • LB1 from Flores, Indonesia, exhibits Down syndrome [Evolution]
    [Aug 2014]

    Human skeletons from Liang Bua Cave, Flores, Indonesia, are coeval with only Homo sapiens populations worldwide and no other previously known hominins. We report here for the first time to our knowledge the occipitofrontal circumference of specimen LB1. This datum makes it possible to link the 430-mL endocranial volume of...
    Categories: Journal Articles
  • How to light a cosmic candle [News Feature]
    [Aug 2014]

    Astronomers are still struggling to identify the companions that help white dwarf stars self-destruct in violent supernovae explosions. Billions of years ago, an ill-fated star not so different from our Sun began to age and balloon outward. As it grew, the star’s glow darkened to a deep, foreboding red, and...
    Categories: Journal Articles
  • Caution needed with model use and assumptions [Social Sciences]
    [Jun 2014]

    The article by Simonit and Perrings (1) describes development of a spatially explicit model of ecosystem service flows associated with reforestation of the Panama Canal watershed. Critical to their study are estimates of water flows, particularly during dry seasons. We have two concerns. First, we agree with Ogden and Stallard’s...
    Categories: Journal Articles
  • 104N/E of p53 is not an adaptively selected site [Biological Sciences]
    [Jun 2014]

    The theories of molecular evolution are very helpful to yield insights into the genetic mechanisms for phenotypes or physiological roles that are difficult to discern in the laboratory. Mutations of functional genes that benefit fitness may experience fixation, especially when they originate in species living in challenging environments where selection...
    Categories: Journal Articles
  • p53 codon 104 is adaptive in Tibetan mammals [Biological Sciences]
    [Jun 2014]

    In our paper, we substantiate the fact that codon 104 variation is adaptive in highland Tibet plateau mammals (1). Liu’s letter (2) claims that codon 104 is not adaptive, which is only based on searching the sequence prediction in National Center for Biotechnology Information (NCBI) without experimental evidence. Although the...
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  • Dengue virus "microRNA-like" small RNA? [Biological Sciences]
    [Jun 2014]

    In PNAS, Hussain and Asgari claim they identified a “microRNA-like” 23-nucleotide RNA expressed by Dengue virus 2 (DENV2), called viral small RNA (vsRNA)-5, in infected mosquito and mammalian cells (1). vsRNA-5, which could also be detected by Northern blot or RT-PCR, was reported to repress DENV2 replication in insect Aag2...
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  • Dengue virus microRNA-like small RNA [Biological Sciences]
    [Jun 2014]

    Skalsky et al. (1) indicate that viral small RNA (vsRNA)-5 (2) was not found in previous deep sequencings, is present in very low abundance, and likely is an RNA interference (RNAi) product. With advancements in next-generation sequencing, progressively deeper sequencing results are obtained. In fact, vsRNA-5 reads were present in...
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  • Bright isolated attosecond soft X-ray pulses [Physics]
    [Jun 2014]

    High harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, to date the shortest subfemtosecond (attosecond, 10−18 s) pulses have been produced only in the extreme UV region of the spectrum below 100 eV, which limits the range of materials...
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  • Nun inhibits RNA polymerase [Biochemistry]
    [Jun 2014]

    The Nun protein of coliphage HK022 arrests RNA polymerase (RNAP) in vivo and in vitro at pause sites distal to phage λ N-Utilization (nut) site RNA sequences. We tested the activity of Nun on ternary elongation complexes (TECs) assembled with templates lacking the λ nut sequence. We report that Nun...
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  • Coevolving network controls catalytic efficiency [Biochemistry]
    [Jun 2014]

    The active sites of enzymes consist of residues necessary for catalysis and structurally important noncatalytic residues that together maintain the architecture and function of the active site. Examples of evolutionary interactions between catalytic and noncatalytic residues have been difficult to define and experimentally validate due to a general intolerance of...
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  • Macrophages regulate fetal testis morphogenesis [Developmental Biology]
    [Jun 2014]

    Organogenesis of the testis is initiated when expression of Sry in pre-Sertoli cells directs the gonad toward a male-specific fate. The cells in the early bipotential gonad undergo de novo organization to form testis cords that enclose germ cells inside tubules lined by epithelial Sertoli cells. Although Sertoli cells are...
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  • TPL-2 kinase regulation by 14-3-3 [Immunology]
    [Jun 2014]

    The MEK-1/2 kinase TPL-2 is critical for Toll-like receptor activation of the ERK-1/2 MAP kinase pathway during inflammatory responses, but it can transform cells following C-terminal truncation. IκB kinase (IKK) complex phosphorylation of the TPL-2 C terminus regulates full-length TPL-2 activation of ERK-1/2 by a mechanism that has remained obscure....
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  • PHLDA3, a novel tumor suppressor of PNETs [Medical Sciences]
    [Jun 2014]

    The molecular mechanisms underlying the development of pancreatic neuroendocrine tumors (PanNETs) have not been well defined. We report here that the genomic region of the PHLDA3 gene undergoes loss of heterozygosity (LOH) at a remarkably high frequency in human PanNETs, and this genetic change is correlated with disease progression and...
    Categories: Journal Articles
  • RP-Mdm2-p53 pathway controls lipid homeostasis [Medical Sciences]
    [Jun 2014]

    The tumor suppressor p53 has recently been shown to regulate energy metabolism through multiple mechanisms. However, the in vivo signaling pathways related to p53-mediated metabolic regulation remain largely uncharacterized. By using mice bearing a single amino acid substitution at cysteine residue 305 of mouse double minute 2 (Mdm2C305F), which renders...
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  • PipX is a global regulator in cyanobacteria [Microbiology]
    [Jun 2014]

    To modulate the expression of genes involved in nitrogen assimilation, the cyanobacterial PII-interacting protein X (PipX) interacts with the global transcriptional regulator NtcA and the signal transduction protein PII, a protein found in all three domains of life as an integrator of signals of the nitrogen and carbon balance. PipX...
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  • Regulation of PSI light harvesting by zeaxanthin [Plant Biology]
    [Jun 2014]

    In oxygenic photosynthetic eukaryotes, the hydroxylated carotenoid zeaxanthin is produced from preexisting violaxanthin upon exposure to excess light conditions. Zeaxanthin binding to components of the photosystem II (PSII) antenna system has been investigated thoroughly and shown to help in the dissipation of excess chlorophyll-excited states and scavenging of oxygen radicals....
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  • Spatial information in the retrosplenial cortex [Neuroscience]
    [Jun 2014]

    The retrosplenial cortex (RSC) is part of a network of interconnected cortical, hippocampal, and thalamic structures harboring spatially modulated neurons. The RSC contains head direction cells and connects to the parahippocampal region and anterior thalamus. Manipulations of the RSC can affect spatial and contextual tasks. A considerable amount of evidence...
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  • Functional MRI at single-cell resolution [Neuroscience]
    [Jun 2014]

    In this work, we show the feasibility of performing functional MRI studies with single-cell resolution. At ultrahigh magnetic field, manganese-enhanced magnetic resonance microscopy allows the identification of most motor neurons in the buccal network of Aplysia at low, nontoxic Mn2+ concentrations. We establish that Mn2+ accumulates intracellularly on injection into...
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  • HIF1{alpha}-driven bone formation requires glycolysis [Physiology]
    [Jun 2014]

    The bone marrow environment is among the most hypoxic in the body, but how hypoxia affects bone formation is not known. Because low oxygen tension stabilizes hypoxia-inducible factor alpha (HIFα) proteins, we have investigated the effect of expressing a stabilized form of HIF1α in osteoblast precursors. Brief stabilization of HIF1α...
    Categories: Journal Articles