2,223 research outputs found
The paralytic shellfish toxin profiles and global distribution of the dinoflagellate Alexandrium minutum Halim
A comprehensive review was undertaken of the distribution of the toxic dinoflagellate Alexandrium minutum Halim. The primary threat to humans caused by A. minutum is because of the production of paralytic shellfish toxins (PSTs) which can accumulate in seafood vectors, which if consumed lead to the human condition known as paralytic shellfish poisoning. Within this work it became apparent that the known global spread of this important species has increased, either due to range expansion, as a consequence of improved or novel investigation, or as a combination of these factors.
Those populations of A. minutum capable of producing PSTs display a range of different toxin profiles with differing saxitoxin derivatives or differing proportions of common toxins being present. As yet no genetic basis for these differences in toxin productivity has been isolated although there are currently 4 recognised clades within the A. minutum species the two principle clades being the Pacific and the Global. A novel analysis of A. minutum toxin profiles was undertaken by applying K means clustering to PST profiles extracted from the literature. This analysis generated 5 distinctive clusters, each relating to a statistically separable toxin profile. Interestingly examples of each of the two major clades had representatives from different toxin profile clusters. This suggests further, currently undetermined genetic separation or relatedness between clades, as the differences in the ITS region of the ribosome upon which the clades are based, does not seem to be coupled to the specifics of the toxin profile. It also raises the possibility that there is an environmental driver for the differing toxin profiles, although profiles clustered geographically in some cases in others they were either cosmopolitan or spatially isolated. This new approach offers an additional tool with which to examine the relationships between populations and target further genetic research
Highly-functionalised difluorinated cyclohexane polyols via the DielsâAlder reaction : regiochemical control via the phenylsulfonyl group
A difluorinated dienophile underwent cycloaddition reactions with a range of furans to afford cycloadducts whichcould be processed regio- and stereoselectively via episulfonium ions, generated by the reaction between their alkenyl groups and phenylsulfenyl chloride. The oxabicyclic products were oxidised to the phenylsulfonyl level and ring opened via E1CB or reductive desulfonative pathways to afford, ultimately, difluorinated cyclohexene or cyclohexane polyols
A review of the global distribution of Alexandrium minutum (Dinophyceae) and comments on ecology and associated paralytic shellfish toxin profiles, with a focus on Northern Europe
Alexandrium minutum is a globally distributed harmful algal bloom species with many strains that are known to produce paralytic shellfish toxins (PSTs) and consequently represent a concern to human and ecosystem health. This review highlights that A. minutum typically occurs in sheltered locations, with cell growth occurring during periods of stable water conditions. Sediment characteristics are important in the persistence of this species within a location, with fine sediments providing cyst deposits for ongoing inoculation to the water column. Toxic strains of A. minutum do not produce a consistent toxin profile, different populations produce a range of PSTs in differing quantities. Novel cluster analysis of published A. minutum toxin profiles indicates five PST profile clusters globally. Some clusters are grouped geographically (Northern Europe) whilst others are widely spread. Isolates from Taiwan have a range of toxin profile clusters and this area appears to have the most diverse set of PST producing A. minutum populations. These toxin profiles indicate that within the UK there are two populations of A. minutum grouping with strains from Northern France and Southern Ireland. There is a degree of interconnectivity in this region due to oceanic circulation and a high level of shipping and recreational boating. Further research into the interrelationships between the A. minutum populations in this global region would be of value
An evaluation of Paralytic Shellfish Toxin occurrence and magnitude around the UK coast since 2008; using chemotaxonomy to maximise routine monitoring data
A dedicated monitoring programme exists within the UK for the analysis of marine biotoxins of microalgal origin, in shellfish from classified production areas. For England, Wales and Scotland this is currently delivered by Cefas on behalf of the Food Standards Agency (FSA) and Food Standards Scotland (FSS). This monitoring programme tests for three groups of toxins, including the paralytic shellfish toxins (PSTs), using chemical analytical techniques, as well as identifying their causative organisms, using light microscopy. Although toxicity and toxin profile within shellfish from around the UK is well documented, since the implementation of chemical analytical testing, the underlying causative microalgal species remain undetermined in most areas. This is due to a lack of resource within the monitoring programme to perform definitive identification following light microscopy and a lack of specific research work confirming the toxin producers in all areas. Presented here is an analysis of PST shellfish toxicity data from the UK monitoring programme displaying trends in distribution and magnitude of PSTs in shellfish over the last 15 years of monitoring. Further to this, toxin profile data generated following the implementation of HPLC-FLD for monitoring PSTs is analysed. This PST toxin profile analysis is used to offer a possible proxy method for the identification of microalgal species by their differing PST toxin profile as presented in the literature. The possible distribution of causative organisms is evaluated using this chemotaxonomic technique to allow for targeted future work
Questions and Instructional Development
Questions Designed to Release Creative Energy and Remove Constraints
Questions Designed to Promote Clarification and Focusin
Questions and Instructional Development
Questions Designed to Release Creative Energy and Remove Constraints
Questions Designed to Promote Clarification and Focusin
Substructure in clusters containing wide-angle tailed radio galaxies. I. New redshifts
We present new redshifts and positions for 635 galaxies in nine rich clusters
containing Wide-Angle Tailed (WAT) radio galaxies. Combined with existing data,
we now have a sample of 18 WAT-containing clusters with more than 10 redshifts.
This sample contains a substantial portion of the WAT clusters in the VLA 20 cm
survey of Abell clusters, including 75% of WAT clusters in the complete survey
(z0.09. It is a representative sample
which should not contain biases other than selection by radio morphology. We
graphically present the new data using histograms and sky maps. A
semi-automated procedure is used to search for emission lines in the spectra in
order to add and verify galaxy redshifts. We find that the average apparent
fraction of emission line galaxies is about 9% in both the clusters and the
field. We investigate the magnitude completeness of our redshift surveys with
CCD data for a test case, Abell 690. This case indicates that our galaxy target
lists are deeper than the detection limit of a typical MX exposure, and they
are 82% complete down to R=19.0. The importance of the uniformity of the
placement of fibers on targets is posited, and we evaluate this in our
datasets. We find some cases of non-uniformities which may influence dynamical
analyses. A second paper will use this database to look for correlations
between the WAT radio morphology and the cluster's dynamical state.Comment: 15 pages, 5 figures, 7 tables. To appear in the Astronomical Journa
Stochastic Processes in Yellow and Red Pulsating Variables
Random changes in pulsation period are well established in cool pulsating
stars, in particular the red giant variables: Miras, semi-regulars of types A
and B, and RV Tau variables. Such effects are also observed in a handful of
Cepheids, the SX Phe variable XX Cyg, and, most recently, the red supergiant
variable, BC Cyg, a type C semi-regular. The nature of such fluctuations is
seemingly random over a few pulsation cycles of the stars, yet the regularity
of the primary pulsation mechanism dominates over the long term. The degree of
stochasticity is linked to the dimensions of the stars, the randomness
parameter 'e' appearing to correlate closely with mean stellar radius through
the period 'P', with an average value of e/P = 0.0136+-0.0005. The physical
processes responsible for such fluctuations are uncertain, but presumably
originate in temporal modifications of envelope convection in such stars.Comment: Poster given at the "Stellar Pulsation: Challenges for Theory and
Observation" conference in Santa Fe, New Mexico (2009
Not in my back yard! Sports stadia location and the property market
In recent years sports stadia have been built in the UK, not only for their intended sporting purpose but with the twin aim of stimulating economic and physical regeneration. However, proposals to locate stadia in urban areas often prompt a negative reaction from local communities, fearing a decline in property prices. This paper will use a case study of the Millennium Stadium in Cardiff and the City of Manchester Stadium to illustrate that in contrast to this widely held belief, sports stadia can actually enhance the value of residential property. Furthermore, it will argue that stadia also contribute indirectly to property value through the creation of pride, confidence and enhanced image of an area.</p
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