1,024 research outputs found

    Whole genome single nucleotide polymorphism based phylogeny of Francisella tularensis and its application to the development of a strain typing assay

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    <p>Abstract</p> <p>Background</p> <p>A low genetic diversity in <it>Francisella tularensis </it>has been documented. Current DNA based genotyping methods for typing <it>F. tularensis </it>offer a limited and varying degree of subspecies, clade and strain level discrimination power. Whole genome sequencing is the most accurate and reliable method to identify, type and determine phylogenetic relationships among strains of a species. However, lower cost typing schemes are necessary in order to enable typing of hundreds or even thousands of isolates.</p> <p>Results</p> <p>We have generated a high-resolution phylogenetic tree from 40 <it>Francisella </it>isolates, including 13 <it>F. tularensis </it>subspecies <it>holarctica </it>(type B) strains, 26 <it>F. tularensis </it>subsp. <it>tularensis </it>(type A) strains and a single <it>F. novicida </it>strain. The tree was generated from global multi-strain single nucleotide polymorphism (SNP) data collected using a set of six Affymetrix GeneChip<sup>® </sup>resequencing arrays with the non-repetitive portion of LVS (type B) as the reference sequence complemented with unique sequences of SCHU S4 (type A). Global SNP based phylogenetic clustering was able to resolve all non-related strains. The phylogenetic tree was used to guide the selection of informative SNPs specific to major nodes in the tree for development of a genotyping assay for identification of <it>F. tularensis </it>subspecies and clades. We designed and validated an assay that uses these SNPs to accurately genotype 39 additional <it>F. tularensis </it>strains as type A (A1, A2, A1a or A1b) or type B (B1 or B2).</p> <p>Conclusion</p> <p>Whole-genome SNP based clustering was shown to accurately identify SNPs for differentiation of <it>F. tularensis </it>subspecies and clades, emphasizing the potential power and utility of this methodology for selecting SNPs for typing of <it>F. tularensis </it>to the strain level. Additionally, whole genome sequence based SNP information gained from a representative population of strains may be used to perform evolutionary or phylogenetic comparisons of strains, or selection of unique strains for whole-genome sequencing projects.</p

    COMPUTER SIMULATIONS OF POSSIBLE FUTURES FOR TWO FLOCKS OF WHOOPING CRANES

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    We conducted computer simulations using the program VORTEX (version 7) to project population sizes, growth rates, genetic diversity, and probabilities of extinction over the next 100 years for 2 flocks of whooping cranes (Grus americana), the Aransas/Wood Buffalo population and the experimental Florida population. Standard runs based on best estimates of demographic. genetic, and environmental parameter values were used as a baseline to which several alternative scenarios were compared. Results generally supported the conclusion of the earlier Population Viability Assessment (Mirande et al. 1991) that the AransaslWood Buffalo population will continue to grow steadily with less than a 1 % probability of extinction. It was noted, however, that a combination of negative factors such as shrinking habitat and increased probabilities of catastrophes accompanied by increased mortality rates could put this population at risk. Results for the Florida population were less optimistic. The standard run produced a population growth rate (r) of only 0.0026 for the next 100 years, and this shifted down to -0.0001 over a 200-year time frame. Adult mortality in this flock would have to be about 20% lower than the predicted value (10%) in order to raise growth rates to above r = 0.02. Amount and duration of supplementation of the Florida flock had minimal impacts on the long-tenn growth rate of the flock. It is the enduring rates of mortality, breeding, and disease risk that will have major effects on this population. For example, if disease risks tum out to be greater than the best-estimate scenario, this population could face a relatively high risk of extinction (17%). The formula for success in Florida is lower adult mortality, lower age of first breeding, lower disease risk, and higher productivity than the best-guess estimates. Fortunately, there are some potential management interventions (e.g., predator control, vaccines and health monitoring, selective introductions to balance the sex ratio of the flock) that may be able to push the odds in favor of success

    The Xist lncRNA interacts directly with SHARP to silence transcription through HDAC3

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    Many long non-coding RNAs (lncRNAs) affect gene expression, but the mechanisms by which they act are still largely unknown. One of the best-studied lncRNAs is Xist, which is required for transcriptional silencing of one X chromosome during development in female mammals. Despite extensive efforts to define the mechanism of Xist-mediated transcriptional silencing, we still do not know any proteins required for this role. The main challenge is that there are currently no methods to comprehensively define the proteins that directly interact with a lncRNA in the cell. Here we develop a method to purify a lncRNA from cells and identify proteins interacting with it directly using quantitative mass spectrometry. We identify ten proteins that specifically associate with Xist, three of these proteins—SHARP, SAF-A and LBR—are required for Xist-mediated transcriptional silencing. We show that SHARP, which interacts with the SMRT co-repressor that activates HDAC3, is not only essential for silencing, but is also required for the exclusion of RNA polymerase II (Pol II) from the inactive X. Both SMRT and HDAC3 are also required for silencing and Pol II exclusion. In addition to silencing transcription, SHARP and HDAC3 are required for Xist-mediated recruitment of the polycomb repressive complex 2 (PRC2) across the X chromosome. Our results suggest that Xist silences transcription by directly interacting with SHARP, recruiting SMRT, activating HDAC3, and deacetylating histones to exclude Pol II across the X chromosome

    The effect of particle size on the biodistribution of low-modulus hydrogel PRINT particles

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    There is a growing recognition that the deformability of particles used for drug delivery plays a significant role on their biodistribution and circulation profile. Understanding these effects would provide a crucial tool for the rational design of drug delivery systems. While particles resembling red blood cells (RBCs) in size, shape and deformability have extended circulation times and altered biodistribution profiles compared to rigid, but otherwise similar particles, the in vivo behavior of such highly deformable particles of varied size has not been explored. We report the fabrication of a series of discoid, monodisperse, low-modulus hydrogel particles with diameters ranging from 0.8 to 8.9 ÎĽm, spanning sizes smaller than and larger than RBCs. We injected these particles into healthy mice, and tracked their concentration in the blood and their distribution into major organs. These deformable particles all demonstrated some hold up in filtration tissues like the lungs and spleen, followed by release back into the circulation, characterized by decreases in particles in these tissues with concomitant increases in particle concentration in blood. Particles similar to red blood cells in size demonstrated longer circulation times, suggesting that this size and shape of deformable particle is uniquely suited to avoid clearance

    Photosensitive drugs: a review on their photoprotection by liposomes and cyclodextrins.

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    Nowadays, an exciting challenge in the drug chemistry and technology research is represented by the development of methods aimed to protect molecular integrity and therapeutic activity of drugs from effects of light. The photostability characterization is ruled by ICH (The International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use), which releases details throughout basic protocols of stability tests to be performed on new medicinal products for human use. The definition of suitable photoprotective systems is fundamental for pharmaceutical manufacturing and for human healthy as well, since light exposure may affect either drugs or drug formulations giving rise even to allergenic or mutagenic by-products. Here, we summarize and discuss the recent studies on the formulation of photosensitive drugs into supramolecular systems, capable of entrapping the molecules in a hollow of their structure by weak noncovalent interactions and protecting them from light. The best known supramolecular matrices belong to the 'auto-assembled' structures, of which liposomes are the most representative, and the 'host-guest' systems, of which cyclodextrins represent the most common 'host' counterpart. A relevant number of papers concerning the use of both liposomes and cyclodextrins as photoprotection systems for drugs has been published over the last 20 years, demonstrating that this topic captures interest in an increasing number of researchers

    The Grizzly, October 22, 1991

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    Alumni Return for Homecoming Celebration • Phi Beta Kappa Charter Approved for Ursinus • Thomas Confirmed to Supreme Court • Gibson to Speak at Ursinus • GALA Seeks Recognition • U.S.G.A. Minutes • GALA Comes Out • Modern Medical Imaging • The Vision of Science Through Art • Beware of Bad Moods • Woman Fixing Her Hair? • Critics\u27 Corner: The Fisher King; Sleeping With the Enemy • Giggles Night Club Comedians • Letters: In Defense of Harley; Harassment Response; An Appeal for the Trees • Apples and Oranges • Dining Turf • Bears Blank the Bullets in Homecoming Game • Cross Country Runs to Victory • Field Hockey Strikes Back, Raises Record to 5-5-2 • Volleyball Spikes Cabrini • Lady Bears Cruise to 1st Place • Winds Fill Ursinus\u27 Sails • Soccer Bounces Back with Three Straight Winshttps://digitalcommons.ursinus.edu/grizzlynews/1280/thumbnail.jp

    The IceCube Neutrino Observatory: Instrumentation and Online Systems

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    The IceCube Neutrino Observatory is a cubic-kilometer-scale high-energy neutrino detector built into the ice at the South Pole. Construction of IceCube, the largest neutrino detector built to date, was completed in 2011 and enabled the discovery of high-energy astrophysical neutrinos. We describe here the design, production, and calibration of the IceCube digital optical module (DOM), the cable systems, computing hardware, and our methodology for drilling and deployment. We also describe the online triggering and data filtering systems that select candidate neutrino and cosmic ray events for analysis. Due to a rigorous pre-deployment protocol, 98.4% of the DOMs in the deep ice are operating and collecting data. IceCube routinely achieves a detector uptime of 99% by emphasizing software stability and monitoring. Detector operations have been stable since construction was completed, and the detector is expected to operate at least until the end of the next decade.Comment: 83 pages, 50 figures; updated with minor changes from journal review and proofin
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