228 research outputs found
Rapid Identification of the Foodborne Pathogen Trichinella spp. by Matrix- Assisted Laser Desorption/Ionization Mass Spectrometry
Human trichinellosis occurs through consumption of raw or inadequately
processed meat or meat products containing larvae of the parasitic nematodes
of the genus Trichinella. Currently, nine species and three genotypes are
recognized, of which T. spiralis, T. britovi and T. pseudospiralis have the
highest public health relevance. To date, the differentiation of the larvae to
the species and genotype level is based primarily on molecular methods, which
can be relatively time consuming and labor intensive. Due to its rapidness and
ease of use a matrix assisted laser desorption / ionization time of flight
mass spectrometry (MALDI-TOF MS) reference spectra database using Trichinella
strains of all known species and genotypes was created. A
formicacid/acetonitrile protein extraction was carried out after pooling 10
larvae of each Trichinella species and genotype. Each sample was spotted 9
times using α-cyano 4-hydoxy cinnamic acid matrix and a MicroFlex LT mass
spectrometer was used to acquire 3 spectra (m/z 2000 to 20000 Da) from each
spot resulting in 27 spectra/species or genotype. Following the spectra
quality assessment, Biotyper software was used to create a main spectra
library (MSP) representing nine species and three genotypes of Trichinella.
The evaluation of the spectra generated by MALDI-TOF MS revealed a
classification which was comparable to the results obtained by molecular
methods. Also, each Trichinella species utilized in this study was distinct
and distinguishable with a high confidence level. Further, different
conservation methods such as freezing and conservation in alcohol and the host
species origin of the isolated larvae did not have a significant influence on
the generated spectra. Therefore, the described MALDI-TOF MS can successfully
be implemented for both genus and species level identification and represents
a major step forward in the use of this technique in foodborne parasitology
The structure of deuterated benzene films adsorbed on the graphite (0001) basal plane: what happens below and above the monolayer coverage?
An exact description of the interactions in aromatic carbon systems is a key condition for the design of carbon based nanomaterials. In this paper we investigate the binding and adsorbate structure of the simplest prototype system in this class – the single aromatic ring molecule benzene on graphite. We have collected neutron diffraction data of the ordered phase of deuterated benzene, C6D6, adsorbed on the graphite (0001) basal plane surface. We examined relative coverages from 0.15 up to 1.3 monolayers (ML) in a temperature range of 80 to 250 K. The results confirm the flat lying commensurate (√7 x √7) R19.1° monolayer with lattice constants a = b = 6.5 Å at coverages of less than 1 ML. For this structure we observe a progressive melting well below the desorption temperature. At higher coverages we do neither observe an ordered second layer nor a densification of the structure by upright tilting of first layer molecules, as generally assumed up to now. Instead, we see the formation of clusters with a bulk crystalline structure for coverages only weakly exceeding 1 ML
Targeted multiplexed selected reaction monitoring analysis evaluates protein expression changes of molecular risk factors for major psychiatric disorders
Background: Extensive research efforts have generated genomic, transcriptomic, proteomic, and functional data hoping to elucidate psychiatric pathophysiology. Selected reaction monitoring, a recently developed targeted proteomic mass spectrometric approach, has made it possible to evaluate previous findings and hypotheses with high sensitivity, reproducibility, and quantitative accuracy. Methods: Here, we have developed a labelled multiplexed selected reaction monitoring assay, comprising 56 proteins previously implicated in the aetiology of major psychiatric disorders, including cell type markers or targets and effectors of known psychopharmacological interventions. We analyzed postmortem anterior prefrontal cortex (Brodmann area 10) tissue of patients diagnosed with schizophrenia (n = 22), bipolar disorder (n = 23), and major depressive disorder with (n = 11) and without (n = 11) psychotic features compared with healthy controls (n = 22). Results: Results agreed with several previous studies, with the finding of alterations of Wnt-signalling and glutamate receptor abundance predominately in bipolar disorder and abnormalities in energy metabolism across the neuropsychiatric disease spectrum. Calcium signalling was predominantly affected in schizophrenia and affective psychosis. Interestingly, we were able to show a decrease of all 4 tested oligodendrocyte specific proteins (MOG, MBP, MYPR, CNPase) in bipolar disorder and to a lesser extent in schizophrenia and affective psychosis. Finally, we provide new evidence linking ankyrin 3 specifically to affective psychosis and the 22q11.2 deletion syndrome-associated protein septin 5 to schizophrenia. Conclusions: Our study highlights the potential of selected reaction monitoring to evaluate the protein abundance levels of candidate markers of neuropsychiatric spectrum disorders, providing a high throughput multiplex platform for validation of putative disease markers and drug targets
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Motion of water monomers reveals a kinetic barrier to ice nucleation on graphene.
The interfacial behaviour of water remains a central question to fields as diverse as protein folding, friction and ice formation. While the properties of water at interfaces differ from those in the bulk, major gaps in our knowledge limit our understanding at the molecular level. Information concerning the microscopic motion of water comes mostly from computation and, on an atomic scale, is largely unexplored by experiment. Here, we provide a detailed insight into the behaviour of water monomers on a graphene surface. The motion displays remarkably strong signatures of cooperative behaviour due to repulsive forces between the monomers, enhancing the monomer lifetime ( ≈ 3 s at 125 K) in a free-gas phase that precedes the nucleation of ice islands and, in turn, provides the opportunity for our experiments to be performed. Our results give a molecular perspective on a kinetic barrier to ice nucleation, providing routes to understand and control the processes involved in ice formation
Differential phenotyping of Brucella species using a newly developed semi-automated metabolic system
<p>Abstract</p> <p>Background</p> <p>A commercial biotyping system (Taxa Profile™, Merlin Diagnostika) testing the metabolization of various substrates by bacteria was used to determine if a set of phenotypic features will allow the identification of members of the genus <it>Brucella </it>and their differentiation into species and biovars.</p> <p>Results</p> <p>A total of 191 different amines, amides, amino acids, other organic acids and heterocyclic and aromatic substrates (Taxa Profile™ A), 191 different mono-, di-, tri- and polysaccharides and sugar derivates (Taxa Profile™ C) and 95 amino peptidase- and protease-reactions, 76 glycosidase-, phosphatase- and other esterase-reactions, and 17 classic reactions (Taxa Profile™ E) were tested with the 23 reference strains representing the currently known species and biovars of <it>Brucella </it>and a collection of 60 field isolates. Based on specific and stable reactions a 96-well "<it>Brucella </it>identification and typing" plate (Micronaut™) was designed and re-tested in 113 <it>Brucella </it>isolates and a couple of closely related bacteria.</p> <p><it>Brucella </it>species and biovars revealed characteristic metabolic profiles and each strain showed an individual pattern. Due to their typical metabolic profiles a differentiation of <it>Brucella </it>isolates to the species level could be achieved. The separation of <it>B. canis </it>from <it>B. suis </it>bv 3, however, failed. At the biovar level, <it>B. abortus </it>bv 4, 5, 7 and <it>B. suis </it>bv 1-5 could be discriminated with a specificity of 100%. <it>B. melitensis </it>isolates clustered in a very homogenous group and could not be resolved according to their assigned biovars.</p> <p>Conclusions</p> <p>The comprehensive testing of metabolic activity allows cluster analysis within the genus <it>Brucella</it>. The biotyping system developed for the identification of <it>Brucella </it>and differentiation of its species and biovars may replace or at least complement time-consuming tube testing especially in case of atypical strains. An easy to handle identification software facilitates the applicability of the Micronaut™ system for microbiology laboratories.</p
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