2,566 research outputs found

    ASSESSING AND MITIGATING LAWN INSECTICIDE HAZARDS TO BEES AND OTHER BENEFICIAL INVERTEBRATES

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    Turfgrass settings, including lawns, golf courses, and sports fields, support many beneficial invertebrates that provide important ecosystem services. These non-target organisms and their associated predation, decomposition, and pollination services can be disrupted by the use of certain insecticides. I compared the ecotoxicity of representatives from three major turf insecticide groups, the neonicotinoids, premix formulations, and the anthranilic diamides, in lab and field realistic settings in order to inform industry initiatives towards environmental sustainability. In lab and field bioassays clothianidin, a neonicotinoid, and a premix clothianidin/pyrethroid spray were acutely toxic to beneficial insects. Populations of predators, springtails, and earthworms, as well as parasitism, predation, and decomposition rates were all reduced. In contrast, chlorantraniliprole, a novel anthranilic diamide with a similar spectrum of pests controlled, had no apparent impact on natural enemies, decomposers, or ecosystem services. This newer class is a good fit for industry initiatives to use relatively less toxic pesticides, with the caveat that golf course superintendents may see secondary pest outbreaks of ants and earthworms. Bumble bee colonies exposed to clothianidin-treated white clover for two weeks suffered acute effects including increased mortality of workers and decreases in the number of honeypots constructed in the hive. When hives were exposed to clothianidin treated clover for six days and then allowed to develop naturally over six weeks they exhibited delayed weight gain and produced no new queens. Colonies exposed to chlorantraniliprole-treated flowers suffered no observable adverse effects. When treated blooms were mowed, colonies exposed to newly-formed blooms exhibited no ill effects. After a single mowing neonicotinoid residues in clover nectar were reduced from \u3e 2000 ng/g, to \u3c 10 ng/g. Residues of imidacloprid were also short-lived in guttation water. Some 50 species of bees and other pollinators were collected from flowering white clover and dandelions in lawns across an urbanization gradient. Such weeds, an underappreciated resource for urban bees, could play a role in pollinator conservation if tolerated and not over-sprayed with broad-spectrum insecticides. Informing the public about the potential benefits these weeds could have for pollinators may help lead to more environmentally conscious management decisions

    The G protein-coupling specificity of D2-like dopamine receptors

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    The G-protein coupling specificity of D2-like dopamine receptors was investigated using both receptor-G protein fusions and membranes of cells in which pertussis toxin-resistant mutants of individual Gi-family G proteins could be expressed in an inducible fashion. A range of ligands displayed agonism at the long isoform of the human dopamine D2 receptor. However, varying degrees of efficacy were observed for individual ligands as monitored by their capacity to load [35S] GTPγS onto each of Gi1, Gi2, Gi3 and Go1. By contrast, S-(-)-3-(3-hydroxyphenyl)-N-propylpiperidine (S-(-)-3PPP) was a partial agonist when Go1 was the target G protein but an antagonist/inverse agonist at Gi1, Gi2, Gi3. In ligand binding assays dopamine identified both high and low affinity states at each of the dopamine D2 receptor-G protein fusion proteins and the high affinity state was eliminated by guanine nucleotide. S-(-)-3PPP bound to an apparent single state of the constructs where the D2 receptor was fused to Gi1, Gi2 or Gi3. However, it bound to distinct high and low affinity states of the D2 receptor-Go1 fusion with the high affinity state being eliminated by guanine nucleotide. Similarly, although dopamine identified guanine nucleotide-sensitive high affinity states of the D2 receptor when expression of pertussis toxin-resistant forms of either Gi2 or Go1 was induced, S-(-)-3PPP identified a high affinity site only in the presence of Go1. These results demonstrate S-(-)-3PPP to be a protean agonist at the D2l receptor and may explain in vivo actions of this ligand. Furthermore, in agreement with previous studies, the ability of the dopamine D2l receptor to couple promiscuously to Gαi1-3, and Gαo1 was demonstrated. However, despite high homology between dopamine D2l and D3 receptors, the G protein-coupling specificity of the D3 receptor has not been well characterised. Again using both receptor-G protein fusions and membranes of cells in which pertussis toxin-resistant mutants of individual Gi-family G proteins could be expressed in an inducible fashion, we confirmed the selective coupling of the D3 receptor to Gαo1. A range of ligands displayed agonism at the D2l receptor and the D3 receptor when coupled to Gαo1. As a general trend, agonists, including dopamine, displayed a higher potency at the D3 receptor. This perhaps reflects the role of D3 as an autoreceptor. Of particular interest was the demonstration that S-(-)-3PPP has both a higher efficacy and potency at the D3 receptor when coupled to Gαo1. The investigations into dopamine receptor-G protein coupling highlighted the utility of the [35S]GTPγS binding assay as a method of directly measuring receptor catalysed nucleotide exchange on the α subunit of G proteins. However, the expense associated with the use of radiolabels makes this assay less attractive, particularly for high-throughput screening programmes. In an attempt to develop a non-radioactive assay equivalent to the [35S] GTPγS assay an immunisation programme was initiated to generate antibodies selective against the active (GTP bound) conformation of G proteins. 4 way primary screening of 1632 hybridomas generated from mice immunized with GTPS-loaded Gi1 and isolated using an automated robotic colony picker, identified 3 antibodies that interacted with the constitutively active Q204L but neither the constitutively inactive G203A nor wild type form of Gi1. This profile extended to other closely related Gi-family G proteins but not to the less closely related Gs and Gq/G11 families. Each of these antibodies was, however, also able to identify wild type, GDP-bound Gi- family G proteins in the presence of AlF4- which mimics the presence of the terminal phosphate of GTP and hence generates an active conformation of the G protein. Stimulation of cells co-expressing a wild type Gisubunit and the dopamine D2 receptor with the agonist ligand nor-apomorphine also allowed these conformation selective antibodies to bind the G protein. Such reagents allow the development of label- free assays for G protein-coupled receptor-mediated activation of Gi- family G proteins

    A Characterization of Extractable, Hydroxylated Fatty Acid Bearing Components in Legionella Pneumophila

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    Extraction of the lipids of Legionella pneumophila yields phases unlike those produced from other Gram-negative bacteria. A viscous interface forms between the aqueous (wash) and organic phases. More than half of the hydroxylated fatty acids were found distributed between the aqueous phase and the interfacial material, fractions in which such constituents have not been reported in other Gram-negative species. It was further observed that after the material from the aqueous/interfacial phase was dissolved in methanol or chloroform/methanol (2:1 (V/V)), the addition of acetone would create a white, flocculent precipitate. Analyses showed that the supernatant contained fatty acids that were nonhydroxylated and the precipitate contained both nonhydroxylated and hydroxylated fatty acids. The acetone precipitate could be further purified by column chromatography. Material was eluted from a silicic acid column with sequential additions of chloroform, acetone, and methanol. It was found that the methanol fraction contained the majority of the hydroxylated fatty acid containing material. An improved method for extracting LPS-like material from Legionella pneumophila is presented. This study suggests that LPS-like material can be obtained from L. pneumophila in higher yield (6.4% of total cell weight), of higher purity (as indicated by SDS-PAGE), and by a simpler method than those previously reported. SDS-PAGE profiles of purified (acetone precipitation and column chromatographic separation) LPS-like material extracted with chloroform/methanol (2:1 (V/V)) from L. pneumophila are identical to the previously reported profiles for G. pneumophila LPS. The chemical analyses of the LPS-like material can only account for approximately one-half the isolated material weight. This is suggestive of a moiety that is as of yet undetectable by the means employed to characterize the LPS

    The development of democracy as a political ideal in the second half of the nineteenth century: with special reference to Cambridgeshire, Huntingdonshire, and Co. Durham.

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    This thesis commences with a general review of pre-chartist democratic sentiment in Great Britain followed by a brief study of Chartism's ideology and motivation. It then examines the various aspects of the democratization of the British political system between the years 1850 and 1900. Certain chapters are devoted to key time-spans, notably 1885 and 1867-1868, while others consider particular aspects of electoral practice, including the ballot and women’s suffrage. Other chapters consider the Reform movement prior to 1867, the distribution of parliamentary constituencies, the House of Lords and other, less prominent, issues. The thesis addressed events on the national stage, and the opinions of national political figures, but equal weight is accorded to, and" where possible a comparison attempted with, local political opinion. The latter has been sampled essentially via the local press but, as well as local newspaper editorials, the thesis also extensively quotes the opinions of locally-elected MPs, local political figures and local Reform activists. The two localities studied were selected to provide a comparison in themselves. Hence, as well as national against local and Liberal against Conservative, opinion in rural Tory-dominated Cambridgeshire is compared with that of industrial and overwhelmingly Liberal County Durham. The thesis concludes with an overall review and a short survey of the changing national and local attitudes to "democracy" as such

    Fostering a Pedagogy of Mutual Engagement Through a Shared Practice of Aikido

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    A preliminary investigation into the use of amino acids as potential ion pairs for diclofenac transdermal delivery

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    Ion pairing is a potential strategy used to increase the partition and permeation of ionisable drug molecules. This work outlines the process of identifying, selecting and testing potential counter ions for diclofenac (DF). Three screening criteria were considered in the initial selection process. The first, toxicity, was used to eliminate counter ion candidates that could not be used in topical formulations. The second related to the balancing of charges. As DF is a free acid in its unionised state, counter ions should be of a basic character. Finally, molecular size, as represented by molecular mass (Da), was used. Because of the impact on ion pair formation, the counter ion was required to have a lower molecular weight than diclofenac. Basic amino acids L-Arginine, L-Histidine, L-Lysine and their salts were chosen. The selection process concluded with Partition Coefficient (PC) studies. These were used to identify any counter ions able to interact electrostatically with the ionised DF, enabling the ‘neutral’ ion pair to partition from an aqueous into an organic layer. Permeation studies using porcine skin were performed to test the efficacy of any selected counter ion. These preliminary studies suggest that amino acids may be used as counter ions to increase the partition and permeation of ionisable drugs
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