Proceedings of the Natural Academy of Sciences

Proceedings of the National Academy of Sciences RSS feed -- current issue
  • Lens design for electromagnetic lithotripters [Engineering]
    [Apr 2014]

    The efficiency of shock wave lithotripsy (SWL), a noninvasive first-line therapy for millions of nephrolithiasis patients, has not improved substantially in the past two decades, especially in regard to stone clearance. Here, we report a new acoustic lens design for a contemporary electromagnetic (EM) shock wave lithotripter, based on recently...
    Categories: Journal Articles
  • SpyLigase-generated polymers for cell capture [Biochemistry]
    [Apr 2014]

    Individual proteins can now often be modified with atomic precision, but there are still major obstacles to connecting proteins into larger assemblies. To direct protein assembly, ideally, peptide tags would be used, providing the minimal perturbation to protein function. However, binding to peptides is generally weak, so assemblies are unstable...
    Categories: Journal Articles
  • Flies stabilize flight by sensing wind [Biophysics and Computational Biology]
    [Apr 2014]

    Flies and other insects use vision to regulate their groundspeed in flight, enabling them to fly in varying wind conditions. Compared with mechanosensory modalities, however, vision requires a long processing delay (~100 ms) that might introduce instability if operated at high gain. Flies also sense air motion with their antennae,...
    Categories: Journal Articles
  • Dynamic FtsZ couples to MinCDE [Biophysics and Computational Biology]
    [Apr 2014]

    In Escherichia coli, a contractile ring (Z-ring) is formed at midcell before cytokinesis. This ring consists primarily of FtsZ, a tubulin-like GTPase, that assembles into protofilaments similar to those in microtubules but different in their suprastructures. The Min proteins MinC, MinD, and MinE are determinants of Z-ring positioning in E....
    Categories: Journal Articles
  • Mapping high-pressure states of proteins with DEER [Biophysics and Computational Biology]
    [Apr 2014]

    The dominance of a single native state for most proteins under ambient conditions belies the functional importance of higher-energy conformational states (excited states), which often are too sparsely populated to allow spectroscopic investigation. Application of high hydrostatic pressure increases the population of excited states for study, but structural characterization is...
    Categories: Journal Articles
  • M2 macrophages promote beta-cell proliferation [Cell Biology]
    [Apr 2014]

    Determination of signaling pathways that regulate beta-cell replication is critical for beta-cell therapy. Here, we show that blocking pancreatic macrophage infiltration after pancreatic duct ligation (PDL) completely inhibits beta-cell proliferation. The TGFβ superfamily signaling inhibitor SMAD7 was significantly up-regulated in beta cells after PDL. Beta cells failed to proliferate in...
    Categories: Journal Articles
  • RSPO-LGR4 signals via IQGAP1 [Cell Biology]
    [Apr 2014]

    R-spondins (RSPOs) and their receptor leucine-rich repeat-containing G-protein coupled receptor 4 (LGR4) play pleiotropic roles in normal and cancer development as well as the survival of adult stem cells through potentiation of Wnt signaling. Current evidence indicates that RSPO–LGR4 functions to elevate levels of Wnt receptors through direct inhibition of...
    Categories: Journal Articles
  • Golgi fragmentation enhances A{beta} production [Cell Biology]
    [Apr 2014]

    Golgi fragmentation occurs in neurons of patients with Alzheimer’s disease (AD), but the underlying molecular mechanism causing the defects and the subsequent effects on disease development remain unknown. In this study, we examined the Golgi structure in APPswe/PS1∆E9 transgenic mouse and tissue culture models. Our results show that accumulation of...
    Categories: Journal Articles
  • Role of BRCA1 in brain development [Cell Biology]
    [Apr 2014]

    Breast cancer susceptibility gene 1 (BRCA1) is a breast and ovarian cancer tumor suppressor whose loss leads to DNA damage and defective centrosome functions. Despite its tumor suppression functions, BRCA1 is most highly expressed in the embryonic neuroepithelium when the neural progenitors are highly proliferative. To determine its functional significance,...
    Categories: Journal Articles
  • Thermosensitive TRPA1 of Bombyx [Developmental Biology]
    [Apr 2014]

    In the bivoltine strain of the silkworm, Bombyx mori, embryonic diapause is induced transgenerationally as a maternal effect. Progeny diapause is determined by the environmental temperature during embryonic development of the mother; however, its molecular mechanisms are largely unknown. Here, we show that the Bombyx TRPA1 ortholog (BmTrpA1) acts as...
    Categories: Journal Articles
  • DPP4 vaccine for type 2 diabetes [Medical Sciences]
    [Apr 2014]

    The increasing prevalence of type 2 diabetes mellitus is associated with a significant economic burden. We developed a dipeptidyl peptidase 4 (DPP4)-targeted immune therapy to increase glucagon-like peptide 1 hormone levels and improve insulin sensitivity for the prevention and treatment of type 2 diabetes mellitus. Immunization with the DPP4 vaccine...
    Categories: Journal Articles
  • Complete replication of HBV and HCV in HLCZ01 cell [Microbiology]
    [Apr 2014]

    The absence of a robust cell culture system for hepatitis B virus (HBV) and hepatitis C virus (HCV) infection has limited the analysis of the virus lifecycle and drug discovery. We have established a hepatoma cell line, HLCZ01, the first cell line, to the authors’ knowledge, supporting the entire lifecycle...
    Categories: Journal Articles
  • Neurexophilin-1 in synaptic plasticity [Neuroscience]
    [Apr 2014]

    Neurotransmission at different synapses is highly variable, and cell-adhesion molecules like α-neurexins (α-Nrxn) and their extracellular binding partners determine synapse function. Although α-Nrxn affect transmission at excitatory and inhibitory synapses, the contribution of neurexophilin-1 (Nxph1), an α-Nrxn ligand with restricted expression in subpopulations of inhibitory neurons, is unclear. To reveal...
    Categories: Journal Articles
  • PDF stabilizes PER in clock neurons [Neuroscience]
    [Apr 2014]

    The neuropeptide PDF is important for Drosophila circadian rhythms: pdf01 (pdf-null) animals are mostly arrhythmic or short period in constant darkness and have an advanced activity peak in light–dark conditions. PDF contributes to the amplitude, synchrony, as well as the pace of circadian rhythms within clock neurons. PDF is known...
    Categories: Journal Articles
  • Neurexin diversity [Neuroscience]
    [Apr 2014]

    Neurexins are evolutionarily conserved presynaptic cell-adhesion molecules that are essential for normal synapse formation and synaptic transmission. Indirect evidence has indicated that extensive alternative splicing of neurexin mRNAs may produce hundreds if not thousands of neurexin isoforms, but no direct evidence for such diversity has been available. Here we use...
    Categories: Journal Articles
  • Lateral root formation requires a carotenoid [Plant Biology]
    [Apr 2014]

    In plants, continuous formation of lateral roots (LRs) facilitates efficient exploration of the soil environment. Roots can maximize developmental capacity in variable environmental conditions through establishment of sites competent to form LRs. This LR prepattern is established by a periodic oscillation in gene expression near the root tip. The spatial...
    Categories: Journal Articles
  • Suppression disrupts unconscious memories [Psychological and Cognitive Sciences]
    [Apr 2014]

    Suppressing retrieval of unwanted memories reduces their later conscious recall. It is widely believed, however, that suppressed memories can continue to exert strong unconscious effects that may compromise mental health. Here we show that excluding memories from awareness not only modulates medial temporal lobe regions involved in explicit retention, but...
    Categories: Journal Articles
  • Entropic forces on constrained sequences [Systems Biology]
    [Apr 2014]

    We outline a theory to quantify the interplay of entropic and selective forces on nucleotide organization and apply it to the genomes of single-stranded RNA viruses. We quantify these forces as intensive variables that can easily be compared between sequences, outline a computationally efficient transfer-matrix method for their calculation, and...
    Categories: Journal Articles
  • Correction for Fanelli and Ioannidis, Reply to Nuijten et al.: Reanalyses actually confirm that US studies overestimate effects in softer research [Correction]
    [Apr 2014]

    LETTER TO THE EDITOR Correction for “Reply to Nuijten et al.: Reanalyses actually confirm that US studies overestimate effects in softer research,” by Daniele Fanelli and John P. A. Ioannidis, which appeared in issue 7, February 18, 2014, of Proc Natl Acad Sci USA (111:E714–E715; first published February 4, 2014;...
    Categories: Journal Articles
  • Correction for Burgess et al., High-precision timeline for Earth's most severe extinction [Correction]
    [Apr 2014]

    EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES Correction for “High-precision timeline for Earth’s most severe extinction,” by Seth D. Burgess, Samuel Bowring, and Shu-zhong Shen, which appeared in issue 9, March 4, 2014, of Proc Natl Acad Sci USA (111:3316–3321; first published February 10, 2014; 10.1073/pnas.1317692111). The authors note that Fig. 3...
    Categories: Journal Articles