Antimicrobial activity of gallium against virulent Rhodococcus equiin vitro and in vivo     

Harrington JR  Martens RJ  Cohen ND  Bernstein LR 《Journal of veterinary pharmacology and therapeutics》2006,29(2):121-127

Rhodococcus equi, a facultative intracellular bacterium, causes severe pneumonia in foals. Evidence suggests that most foals become infected very early in life, when they have immature or ineffective innate immune responses. This study evaluated the antimicrobial activity of gallium against R. equi, as a potential chemoprophylactic and therapeutic agent. Rhodococcus equi was grown in media with various concentrations of gallium nitrate (GN), with and without excess iron. GN significantly inhibited growth and killed R. equi, and these effects were abolished with excess iron. Antimicrobial effects of Ga appear to be related to its interference with iron metabolism. Mice were treated orally with gallium maltolate (GaM), 10 or 50 mg/kg BW, or distilled H2O prior to and after experimental infection with R. equi. Six days post-infection, organs were harvested and R. equi concentrations assessed, and serum gallium concentrations determined. GaM was absorbed in a dose-dependent manner, and R. equi tissue burdens were greater in control mice than in all GaM-treated mice. GaM may aid in the control of disease by preventing development of overwhelming R. equi tissue burdens prior to the establishment of requisite innate and adaptive immune responses.  相似文献   

Bacterial taxa that limit sulfur flux from the ocean     

Howard EC  Henriksen JR  Buchan A  Reisch CR  Bürgmann H  Welsh R  Ye W  González JM  Mace K  Joye SB  Kiene RP  Whitman WB  Moran MA 《Science (New York, N.Y.)》2006,314(5799):649-652

Flux of dimethylsulfide (DMS) from ocean surface waters is the predominant natural source of sulfur to the atmosphere and influences climate by aerosol formation. Marine bacterioplankton regulate sulfur flux by converting the precursor dimethylsulfoniopropionate (DMSP) either to DMS or to sulfur compounds that are not climatically active. Through the discovery of a glycine cleavage T-family protein with DMSP methyltransferase activity, marine bacterioplankton in the Roseobacter and SAR11 taxa were identified as primary mediators of DMSP demethylation to methylmercaptopropionate. One-third of surface ocean bacteria harbor a DMSP demethylase homolog and thereby route a substantial fraction of global marine primary production away from DMS formation and into the marine microbial food web.  相似文献   

A fine-scale chimpanzee genetic map from population sequencing     

Auton A  Fledel-Alon A  Pfeifer S  Venn O  Ségurel L  Street T  Leffler EM  Bowden R  Aneas I  Broxholme J  Humburg P  Iqbal Z  Lunter G  Maller J  Hernandez RD  Melton C  Venkat A  Nobrega MA  Bontrop R  Myers S  Donnelly P  Przeworski M  McVean G 《Science (New York, N.Y.)》2012,336(6078):193-198

To study the evolution of recombination rates in apes, we developed methodology to construct a fine-scale genetic map from high-throughput sequence data from 10 Western chimpanzees, Pan troglodytes verus. Compared to the human genetic map, broad-scale recombination rates tend to be conserved, but with exceptions, particularly in regions of chromosomal rearrangements and around the site of ancestral fusion in human chromosome 2. At fine scales, chimpanzee recombination is dominated by hotspots, which show no overlap with those of humans even though rates are similarly elevated around CpG islands and decreased within genes. The hotspot-specifying protein PRDM9 shows extensive variation among Western chimpanzees, and there is little evidence that any sequence motifs are enriched in hotspots. The contrasting locations of hotspots provide a natural experiment, which demonstrates the impact of recombination on base composition.  相似文献   

Comment on "Phonemic diversity supports a serial founder effect model of language expansion from Africa"     

Van Tuyl R  Pereltsvaig A 《Science (New York, N.Y.)》2012,335(6069):657; author reply 657

We show that Atkinson's (Reports, 15 April 2011, p. 346) intriguing proposal--that global linguistic diversity supports a single language origin in Africa--is an artifact of using suboptimal data, biased methodology, and unjustified assumptions. We criticize his approach using more suitable data, and we additionally provide new results suggesting a more complex scenario for the emergence of global linguistic diversity.  相似文献   

Characterization of the immune response of domestic fowl following immunization with proteins extracted from Dermanyssus gallinae     

David Harrington  Hatem Mohi El Din  Jonathan Guy  Karen Robinson  Olivier Sparagano   《Veterinary parasitology》2009,160(3-4):285-294

Dermanyssus gallinae is the most significant ectoparasite of European poultry egg laying production systems due to high costs of control and associated production losses as well as adverse effects on bird welfare. In this study, soluble proteins were extracted from unfed D. gallinae (DGE) using a urea-based detergent and ultra-filtration, passed through a 0.22 μm filter and blended aseptically with adjuvant. One group of laying hens was immunized with DGE and adjuvant (Montanide ISA 50 V) whilst another group (Control) received physiological saline and adjuvant. All birds were immunized on two occasions, 21 days apart. Antibody response to immunization was determined by ELISA and western blotting using immunoglobulins (Igs) extracted from egg yolk. DGE immunization of hens resulted in a significant (P < 0.05) IgY response compared to controls, although there was no significant difference in IgM response between treatments. A number of proteins were identified by western blotting using IgY antibodies from DGE immunized birds, most prominently at 40 and 230 kDa. Analysis of proteins from approximately corresponding bands on SDS-PAGE confirmed the identity of tropomyosin, whilst other proteins showed high sequence homology with myosin and actin from other arachnid and insect species. Immunization of hens with DGE resulted in a 50.6% increase in mite mortality (P < 0.001) 17 h after feeding when tested by an in vitro mite feeding model. Data in this study demonstrate that somatic antigens from D. gallinae can be used to stimulate a protective immune response in laying hens. Further work is needed to identify other proteins of interest that could confer higher protection against D. gallinae, as well as optimization of the vaccination and in vitro testing protocol.  相似文献   

Evaluation of a real-time quantitative polymerase chain reaction assay for detection and quantitation of virulent Rhodococcus equi     

Harrington JR  Golding MC  Martens RJ  Halbert ND  Cohen ND 《American journal of veterinary research》2005,66(5):755-761

OBJECTIVE: To evaluate a real-time quantitative polymerase chain reaction (QPCR) assay in the detection and quantitation of virulent Rhodococcus equi. SAMPLE POPULATION: 1 virulent, 2 intermediately virulent, and 2 avirulent strains of R. equi and 16 isolates of bacteria genetically related to R. equi. PROCEDURE: The QPCR assay was evaluated for detection and quantitation of the virulence-associated gene (vapA) of R. equi in pure culture and in samples of tracheobronchial fluid, which were inoculated with known numbers of virulent R. equi. Results were compared with those derived via quantitative microbial culture and standard polymerase chain reaction methods. RESULTS: The QPCR assay detected the vapA gene in pure culture of R. equi and in tracheobronchial fluid samples that contained as few as 20 CFUs of virulent R. equi/mL and accurately quantitated virulent R. equi to 10(3) CFUs/mL of fluid. The assay was highly specific for detection of the vapA gene of virulent R. equi and was more sensitive than standard polymerase chain reaction for detection of R. equi in tracheobronchial fluid. CONCLUSIONS AND CLINICAL RELEVANCE: The QPCR assay appears to be a rapid and reliable method for detecting and quantitating virulent R. equi. The accuracy of the QPCR assay is comparable to that of quantitative microbial culture. The increased sensitivity of the QPCR method in detection of virulent R. equi should facilitate rapid and accurate diagnosis of R. equi pneumonia in foals.  相似文献   

The Emperor Seamounts: southward motion of the Hawaiian hotspot plume in Earth's mantle     

Tarduno JA  Duncan RA  Scholl DW  Cottrell RD  Steinberger B  Thordarson T  Kerr BC  Neal CR  Frey FA  Torii M  Carvallo C 《Science (New York, N.Y.)》2003,301(5636):1064-1069

The Hawaiian-Emperor hotspot track has a prominent bend, which has served as the basis for the theory that the Hawaiian hotspot, fixed in the deep mantle, traced a change in plate motion. However, paleomagnetic and radiometric age data from samples recovered by ocean drilling define an age-progressive paleolatitude history, indicating that the Emperor Seamount trend was principally formed by the rapid motion (over 40 millimeters per year) of the Hawaiian hotspot plume during Late Cretaceous to early-Tertiary times (81 to 47 million years ago). Evidence for motion of the Hawaiian plume affects models of mantle convection and plate tectonics, changing our understanding of terrestrial dynamics.  相似文献   

Thoracolumbar spinal cord compression due to vertebral process degenerative joint disease in a family of Shiloh Shepherd dogs     

McDonnell JJ  Knowles KE  deLahunta A  Bell JS  Lowrie CT  Todhunter RJ 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2003,17(4):530-537

Five young Shiloh Shepherd Dogs (4 males and 1 female) related by a common sire were studied because of progressive pelvic limb weakness and incoordination. All dogs had a spastic paraparesis and pelvic limb ataxia consistent with an upper motor neuron and general proprioceptive lesion between spinal cord segments T3 and L3. Proliferative lesions involving one or more of the articular processes from the 11th thoracic vertebrae to the 2nd lumbar vertebra were observed on radiographs of the thoracolumbar vertebrae. Dorsal compression of the spinal cord was identified during imaging studies at these sites. Abnormalities of the synovial joints and bony proliferation of the involved articular processes were identified at postmortem examination in 2 dogs. The articular processes and associated vertebral arches protruded into the vertebral canal, indenting the dorsal surface of the spinalcord. Degenerative joint disease (DJD) was identified histologically. A compressive myelopathy was diagnosed in the spinal cord. These dogs were affected by a compressive myelopathy as a consequence of vertebral process DJD that likely has a geneticcomponent. The DJD could have been caused by a primary vertebral malformation or an injury to the processes at a young age causing malarticulation.  相似文献   

Effects of iron modulation on growth and viability of Rhodococcus equi and expression of virulence-associated protein A     

Jordan MC  Harrington JR  Cohen ND  Tsolis RM  Dangott LJ  Weinberg ED  Martens RJ 《American journal of veterinary research》2003,64(11):1337-1346

OBJECTIVE: To determine the importance of iron for in vitro growth of Rhodococcus equi, define potential iron sources in the environment and mechanisms by which R equi may obtain iron from the environment, and assess expression and immunogenicity of iron-regulated proteins. SAMPLE POPULATION: 10 virulent and 11 avirulent strains of R equi. PROCEDURE: In vitro growth rates and protein patterns of R equi propagated in media with normal, excess, or limited amounts of available iron were compared. Immunoblot analyses that used serum from foals naturally infected with R equi and monoclonal antibody against virulence-associated protein (Vap)A were conducted to determine immunogenicity and identity of expressed proteins. RESULTS: Excess iron did not alter growth of any R equi strains, whereas growth of all strains was significantly decreased in response to limited amounts of available iron. Virulent R equi were able to use iron from ferrated deferoxamine, bovine transferrin, and bovine lactoferrin. Only virulent R equi expressed an iron-regulated, immunogenic, surface-associated protein identified as VapA. CONCLUSIONS AND CLINICAL RELEVANCE: Iron is required for the growth and survival of R equi. Sources of iron for R equi, and mechanisms by which R equi acquire iron in vivo, may represent important virulence factors and novel targets for the development of therapeutic and immunoprophylactic strategies to control R equi infection in foals. Expression of VapA is substantially upregulated when there is a limited amount of available iron.  相似文献   

Influence of irrigation on seed potatoes     

F. M. Harrington 《American Journal of Potato Research》1926,3(6):203-205

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