Proceedings of the Natural Academy of Sciences

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  • Function of frontal pole cortex in cognition [Neuroscience]
    [Jul 2015]

    Frontal pole cortex (FPC) and posterior cingulate cortex (PCC) have close neuroanatomical connections, and imaging studies have shown coactivation or codeactivation of these brain regions during performance of certain tasks. However, they are among the least well-understood regions of the primate brain. One reason for this is that the consequences...
    Categories: Journal Articles
  • Power laws for curved hand movements [Neuroscience]
    [Jul 2015]

    In a planar free-hand drawing of an ellipse, the speed of movement is proportional to the −1/3 power of the local curvature, which is widely thought to hold for general curved shapes. We investigated this phenomenon for general curved hand movements by analyzing an optimal control model that maximizes a...
    Categories: Journal Articles
  • Deep homology in filamentous rooting cells [Plant Biology]
    [Jul 2015]

    Land plants develop filamentous cells—root hairs, rhizoids, and caulonemata—at the interface with the soil. Members of the group XI basic helix–loop–helix (bHLH) transcription factors encoded by LOTUS JAPONICUS ROOTHAIRLESS1-LIKE (LRL) genes positively regulate the development of root hairs in the angiosperms Lotus japonicus, Arabidopsis thaliana, and rice (Oryza sativa). Here...
    Categories: Journal Articles
  • Correction for Balakrishnan et al., Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment [Correction]
    [Jul 2015]

    CHEMISTRY, SUSTAINABILITY SCIENCE Correction for “Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment,” by Madhesan Balakrishnan, Eric R. Sacia, Sanil Sreekumar, Gorkem Gunbas, Amit A. Gokhale, Corinne D. Scown, F. Dean Toste, and Alexis T. Bell, which appeared in issue 25, June 23, 2015,...
    Categories: Journal Articles
  • Correction for Zhou et al., NPAS3 is a trachealess homolog critical for lung development and homeostasis [Correction]
    [Jul 2015]

    MEDICAL SCIENCES Correction for “NPAS3 is a trachealess homolog critical for lung development and homeostasis,” by Shutang Zhou, Simone Degan, Erin N. Potts, W. Michael Foster, and Mary E. Sunday, which appeared in issue 28, July 14, 2009, of Proc Natl Acad Sci USA (106:11691–11696; first published July 6, 2009;...
    Categories: Journal Articles
  • Correction for Thompson et al., Identification of hydroxyapatite spherules provides new insight into subretinal pigment epithelial deposit formation in the aging eye [Correction]
    [Jul 2015]

    MEDICAL SCIENCES Correction for “Identification of hydroxyapatite spherules provides new insight into subretinal pigment epithelial deposit formation in the aging eye,” by Richard B. Thompson, Valentina Reffatto, Jacob G. Bundy, Elod Kortvely, Jane M. Flinn, Antonio Lanzirotti, Emrys A. Jones, David S. McPhail, Sarah Fearn, Karsten Boldt, Marius Ueffing, Savanjeet...
    Categories: Journal Articles
  • Correction to Supporting Information for Sullivan et al., Spatially robust estimates of biological nitrogen (N) fixation imply substantial human alteration of the tropical N cycle [SI Correction]
    [Jul 2015]

    ENVIRONMENTAL SCIENCES Correction to Supporting Information for “Spatially robust estimates of biological nitrogen (N) fixation imply substantial human alteration of the tropical N cycle,” by Benjamin W. Sullivan, W. Kolby Smith, Alan R. Townsend, Megan K. Nasto, Sasha C. Reed, Robin L. Chazdon, and Cory C. Cleveland, which appeared in...
    Categories: Journal Articles
  • Optogenetic activation and neuronal function [Biological Sciences]
    [Jul 2015]

    Van Dort et al. (1) used optogenetic activation to demonstrate the capacity of cholinergic neurons in the laterodorsal and pedunculopontine tegmental nuclei (LDT and PPT, respectively) to induce rapid eye movement (REM) sleep. The authors submit that their data clarify the role of LDT/PPT cholinergic neurons in REM sleep initiation,...
    Categories: Journal Articles
  • Questioning the Great Cahokia Flood [Physical Sciences]
    [Jul 2015]

    Munoz et al. (1) present an argument for Cahokia’s demise focusing on a massive flood event ca. A.D. 1200. Although we recognize that a flood event may have occurred, we do not agree with their hypothesis that this event (i) caused the collapse of the largest Pre-Columbian city north of...
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  • Reply to Baires et al.: Flooding at Cahokia [Physical Sciences]
    [Jul 2015]

    Baires et al. (1) critique two aspects of our study (2): (i) whether a large flood event “caused the collapse of the largest Pre-Columbian city north of Mexico,” and (ii) the timing of one flood event (Flood Event V), which we reported to have a 95% confidence interval of A.D....
    Categories: Journal Articles
  • Role of cholinergic neurons in REM sleep control [Biological Sciences]
    [Jul 2015]

    We thank Grace (1) for the opportunity to discuss the role of cholinergic neurons in rapid eye movement (REM) sleep further. Grace suggests that optogenetic activation of a population of neurons does not necessarily demonstrate their role in the endogenous system when interrogating complex neural circuitry. We agree that we...
    Categories: Journal Articles
  • Dynamic remodeling during 3D hMSC migration [Engineering]
    [Jul 2015]

    Biomaterials that mimic aspects of the extracellular matrix by presenting a 3D microenvironment that cells can locally degrade and remodel are finding increased applications as wound-healing matrices, tissue engineering scaffolds, and even substrates for stem cell expansion. In vivo, cells do not simply reside in a static microenvironment, but instead,...
    Categories: Journal Articles
  • Adolescent impatience [Psychological and Cognitive Sciences]
    [Jul 2015]

    Adolescence is a developmental period associated with an increase in impulsivity. Impulsivity is a multidimensional construct, and in this study we focus on one of the underlying components: impatience. Impatience can result from (i) disregard of future outcomes and/or (ii) oversensitivity to immediate rewards, but it is not known which...
    Categories: Journal Articles
  • Renaissance of coal [Sustainability Science]
    [Jul 2015]

    Coal was central to the industrial revolution, but in the 20th century it increasingly was superseded by oil and gas. However, in recent years coal again has become the predominant source of global carbon emissions. We show that this trend of rapidly increasing coal-based emissions is not restricted to a...
    Categories: Journal Articles
  • High-resolution snapshot of Conus toxin arsenal [Biochemistry]
    [Jul 2015]

    Cone snails are predatory marine gastropods characterized by a sophisticated venom apparatus responsible for the biosynthesis and delivery of complex mixtures of cysteine-rich toxin peptides. These conotoxins fold into small highly structured frameworks, allowing them to potently and selectively interact with heterologous ion channels and receptors. Approximately 2,000 toxins from...
    Categories: Journal Articles
  • Structural mechanism of the terminase ATPase motor [Biochemistry]
    [Jul 2015]

    Many viruses package their genomes into procapsids using an ATPase machine that is among the most powerful known biological motors. However, how this motor couples ATP hydrolysis to DNA translocation is still unknown. Here, we introduce a model system with unique properties for studying motor structure and mechanism. We describe...
    Categories: Journal Articles
  • Anticancer mechanism organo-osmium drug candidate [Biochemistry]
    [Jul 2015]

    The organometallic “half-sandwich” compound [Os(η6-p-cymene)(4-(2-pyridylazo)-N,N-dimethylaniline)I]PF6 is 49× more potent than the clinical drug cisplatin in the 809 cancer cell lines that we screened and is a candidate drug for cancer therapy. We investigate the mechanism of action of compound 1 in A2780 epithelial ovarian cancer cells. Whole-transcriptome sequencing identified three...
    Categories: Journal Articles
  • Structure and function of myosin skip residues [Biochemistry]
    [Jul 2015]

    The rod of sarcomeric myosins directs thick filament assembly and is characterized by the insertion of four skip residues that introduce discontinuities in the coiled-coil heptad repeats. We report here that the regions surrounding the first three skip residues share high structural similarity despite their low sequence homology. Near each...
    Categories: Journal Articles
  • SHOT-RNAs enhance cell proliferation in cancers [Biochemistry]
    [Jul 2015]

    Sex hormones and their receptors play critical roles in the development and progression of the breast and prostate cancers. Here we report that a novel type of transfer RNA (tRNA)-derived small RNA, termed Sex HOrmone-dependent TRNA-derived RNAs (SHOT-RNAs), are specifically and abundantly expressed in estrogen receptor (ER)-positive breast cancer and...
    Categories: Journal Articles
  • Single-molecule analysis of the kinesin-8 Kif18B [Biophysics and Computational Biology]
    [Jul 2015]

    Kinesin-8s are plus-end–directed motors that negatively regulate microtubule (MT) length. Well-characterized members of this subfamily (Kip3, Kif18A) exhibit two important properties: (i) They are “ultraprocessive,” a feature enabled by a second MT-binding site that tethers the motors to a MT track, and (ii) they dissociate infrequently from the plus end....
    Categories: Journal Articles