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Sökning: WFRF:(Saunders Pamela)

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  • Ison, Catherine A., et al. (författare)
  • Evolution of Neisseria gonorrhoeae is a continuing challenge for molecular detection of gonorrhoea : false negative gonococcal porA mutants are spreading internationally
  • 2013
  • Ingår i: Sexually Transmitted Infections. - : BMJ Publishing Group Ltd. - 1368-4973 .- 1472-3263. ; 89:3, s. 197-201
  • Tidskriftsartikel (refereegranskat)abstract
    • Objectives: Identification of genetic targets specific to Neisseria gonorrhoeae for use in molecular detection methods has been a challenge. The porA pseudogene in N gonorrhoeae has been commonly used but recently gonococcal isolates giving a negative result in these PCRs have been reported. Here we describe the characterisation of two such gonococcal isolates received by the reference service at the Health Protection Agency, London, England.Methods: Phenotypic characterisation was achieved using conventional biochemical and immunological tests, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF-MS), antimicrobial susceptibility testing, serovar determination and detection of meningococcal PorA using monoclonal antibody 4BG4-E7. Genetic species confirmation was determined using commercial and in house PCRs and 16S rRNA gene sequencing. Molecular typing using the N gonorrhoeae multi-antigen sequence typing (NG-MAST) and multilocus sequence typing (MLST) was performed. The DNA sequence of the full-length gonococcal porA pseudogene was determined and compared with published sequences.Results: Both isolates were confirmed, biochemically and immunologically as N gonorrhoeae, but repeatedly gave negative results with two in house real-time PCR assays for the porA pseudogene. Further characterisation of these isolates identified the presence of a meningococcal porA sequence and showed these isolates belong to serovar Bropyst, and to NG-MAST sequence type (ST) 5967 and MLST ST1901.Conclusions: Gonococcal isolates that give false negative results with porA pseudogene PCR assays have now been identified in four countries, three of which are in Europe, and do not appear clonal. This report highlights the genetic diversity of N gonorrhoeae, which remains a challenge for the molecular detection methods.
  • McMahon, Sean, et al. (författare)
  • Dubiofossils from a Mars‐analogue subsurface palaeoenvironment: The limits of biogenicity criteria
  • 2021
  • Ingår i: Geobiology. - : Wiley-Blackwell. - 1472-4677 .- 1472-4669. ; 19:5, s. 473-488
  • Tidskriftsartikel (refereegranskat)abstract
    • The search for a fossil record of Earth's deep biosphere, partly motivated by potential analogies with subsurface habitats on Mars, has uncovered numerous assemblages of inorganic microfilaments and tubules inside ancient pores and fractures. Although these enigmatic objects are morphologically similar to mineralized microorganisms (and some contain organic carbon), they also resemble some abiotic structures. Palaeobiologists have responded to this ambiguity by evaluating problematic filaments against checklists of “biogenicity criteria”. Here, we describe material that tests the limits of this approach. We sampled Jurassic calcite veins formed through subseafloor serpentinization, a water–rock reaction that can fuel the deep biosphere and is known to have occurred widely on Mars. At two localities ~4 km apart, veins contained curving, branched microfilaments composed of Mg-silicate and Fe-oxide minerals. Using a wide range of analytical techniques including synchrotron X-ray microtomography and scanning transmission electron microscopy, we show that these features meet many published criteria for biogenicity and are comparable to fossilized cryptoendolithic fungi or bacteria. However, we argue that abiotic processes driven by serpentinization could account for the same set of lifelike features, and report a chemical garden experiment that supports this view. These filaments are, therefore, most objectively described as dubiofossils, a designation we here defend from criticism and recommend over alternative approaches, but which nevertheless signifies an impasse. Similar impasses can be anticipated in the future exploration of subsurface palaeo-habitats on Earth and Mars. To avoid them, further studies are required in biomimetic geochemical self-organization, microbial taphonomy and micro-analytical techniques, with a focus on subsurface habitats.
  • Verhoef, Peter, et al. (författare)
  • A Cross-National Investigation into the Marketing Department’s Influence within the Firm: Towards Initial Empirical Generalizations
  • 2011
  • Ingår i: Journal of International Marketing. - 1069-031X .- 1547-7215. ; 19:3, s. 59-86
  • Tidskriftsartikel (refereegranskat)abstract
    • This study of the influence of the marketing department (MD), as well as its relationship with firm performance, includes seven industrialized countries and aims to generalize the conceptual model presented by Verhoef and Leeflang (2009). This investigation considers the antecedents of perceived MD influence, top management respect for the MD, and MD decision influence, as well as the relationships of these three influence variables with market orientation (MO) and business performance (BP). Meta-analytic procedures reveal initial empirical generalizations: Accountability, MD innovativeness, and the customer connection capabilities of the MD relate consistently to all three studied MD influence measures. The generalization also shows that MD influence contributes to BP indirectly through its positive relation- ship with MO and directly through its positive direct relationship with BP.
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  • Resultat 1-5 av 5

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