306 research outputs found

    Evidence for distinct subcellular sites of opiate receptors. Demonstration of opiate receptors in smooth microsomal fractions isolated from rat brain

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    We have found opiate receptors enriched in two distinct subcellular fractions obtained from rat brain cell-free homogenates. By several criteria, one fraction contains synaptic plasma membranes, while the other represents predominantly smooth microsomes. Using marker enzyme analysis, we determined that the occurrence of opiate receptors in the smooth microsomal fraction cannot be attributed to synaptic plasma membrane cross-contamination. Electron microscopic examination revealed that the two fractions enriched in opiate receptors differed markedly in morphology. In particular, smooth microsomes appeared to lack synaptic junctional complexes, postsynaptic densities, or membranes identifiable as presynaptic. Also, opiate receptors in microsomes were localized on membranes which were distinctly higher (p=1.08-1.14 g/ml) than synaptic plasma membrane receptors (p=1.13-1.18 g/ml) when either agonist or antagonist binding was measured. We also studied the characteristics of binding of opiate agonists to both receptor populations. Although both microsomal and synaptic membrane opiate receptors were sensitive to NaCl when agonist binding was assessed, microsomal receptors were considerably less sensitive toguanine nucleotides than were synaptic membrane receptors. The subsensitivity appeared due to the inability of relatively low concentrations of guanine nucleotides (10 μM) to accelerate the dissociation rate of bound peptide ligand. Finally, microsomal opiate receptors displayed faster rates of dissociation (K-1 = 0.077 min1-) than did synaptic membrane receptors (K-1 = 0.017 min-1). The data are discussed in relation to the concepts that microsomal opiate receptors either represent a distinct population of synaptic membranes or newly synthesized receptors in transit to synaptic membrane sites

    Stereospecific opiate-binding sites occur in coated vesicles

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    We prepared clathrin-coated vesicles from bovine forebrain utilizing sucrose or deuterium oxide-Ficoll density gradient centrifugation followed by permeation chromatography. Homogeneity was monitored by electron microscopy (EM) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). EM revealed that the predominant (up to 98% of the total) organelles were coated vesicles and empty hexagonal baskets. Diameters of the coated vesicles ranged from 37 to 120 nm with a mean of 65.2 ± 2.2. Upon SDS-PAGE of the coated vesicle fraction, the most prominent band appeared at 180,000 daltons. There were also three additional bands at 10,000, 50,000 and 35,000 daltons, giving the overall pattern characteristic of coated vesicles. Both 0.5 nM tritiated naltrexone and etorphine displayed specific binding to coated vesicles. Naltrexone binding in coated vesicles from gradient fractions was increased 2.5-fold over the original 100,000 x g pellet. An additional 4-fold enrichment in specific binding was observed after permeation chromatography which was concomitant with an increase in the volume density of coated vesicles in electron micrographs. Naltrexone binding was stereospecific and etorphine binding was inhibited by 100 mM NaCl (40%). Both naltrexone and etorphine binding were inhibited by 50 μM guanyl-5'-yl imidodiphosphate (40 to 50%). In summary, purified bovine brain-coated vesicles contained high affinity stereospecific opiate alkaloid-binding sites with characteristic opioid binding properties

    Revolutionaries, wanderers, converts, and compliants: Life histories of extreme right activists

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    Life-history interviews were conducted with thirty-six extreme right activists in the Netherlands (1996-1998). Becoming an activist was a matter of continuity, of conversion, or of compliance. Continuity denotes life histories wherein movement membership and participation are a natural consequence of prior political socialization; conversion to trajectories wherein movement membership and participation are a break with the past; and compliance to when people enter activism, not owing to personal desires but because of circumstances they deemed were beyond their control. Stories of continuity in our interviews were either testimonies of lifetimes of commitment to extreme right politics (labeled revolutionaries) or lifelong journeys from one political shelter to the other by political wanderers (labeled converts). Activists who told us conversion stories, we labeled converts and those who told compliance stories, compliants. The article presents a prototypical example of each type of career and suggests each prototype to hold for different motivational dynamics. © 2007 Sage Publications

    Measurement of νˉμ\bar{\nu}_{\mu} and νμ\nu_{\mu} charged current inclusive cross sections and their ratio with the T2K off-axis near detector

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    We report a measurement of cross section σ(νμ+nucleusμ+X)\sigma(\nu_{\mu}+{\rm nucleus}\rightarrow\mu^{-}+X) and the first measurements of the cross section σ(νˉμ+nucleusμ++X)\sigma(\bar{\nu}_{\mu}+{\rm nucleus}\rightarrow\mu^{+}+X) and their ratio R(σ(νˉ)σ(ν))R(\frac{\sigma(\bar \nu)}{\sigma(\nu)}) at (anti-)neutrino energies below 1.5 GeV. We determine the single momentum bin cross section measurements, averaged over the T2K νˉ/ν\bar{\nu}/\nu-flux, for the detector target material (mainly Carbon, Oxygen, Hydrogen and Copper) with phase space restricted laboratory frame kinematics of θμ\theta_{\mu}500 MeV/c. The results are σ(νˉ)=(0.900±0.029(stat.)±0.088(syst.))×1039\sigma(\bar{\nu})=\left( 0.900\pm0.029{\rm (stat.)}\pm0.088{\rm (syst.)}\right)\times10^{-39} and $\sigma(\nu)=\left( 2.41\ \pm0.022{\rm{(stat.)}}\pm0.231{\rm (syst.)}\ \right)\times10^{-39}inunitsofcm in units of cm^{2}/nucleonand/nucleon and R\left(\frac{\sigma(\bar{\nu})}{\sigma(\nu)}\right)= 0.373\pm0.012{\rm (stat.)}\pm0.015{\rm (syst.)}$.Comment: 18 pages, 8 figure

    Global data on earthworm abundance, biomass, diversity and corresponding environmental properties

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    14 p.Earthworms are an important soil taxon as ecosystem engineers, providing a variety of crucial ecosystem functions and services. Little is known about their diversity and distribution at large spatial scales, despite the availability of considerable amounts of local-scale data. Earthworm diversity data, obtained from the primary literature or provided directly by authors, were collated with information on site locations, including coordinates, habitat cover, and soil properties. Datasets were required, at a minimum, to include abundance or biomass of earthworms at a site. Where possible, site-level species lists were included, as well as the abundance and biomass of individual species and ecological groups. This global dataset contains 10,840 sites, with 184 species, from 60 countries and all continents except Antarctica. The data were obtained from 182 published articles, published between 1973 and 2017, and 17 unpublished datasets. Amalgamating data into a single global database will assist researchers in investigating and answering a wide variety of pressing questions, for example, jointly assessing aboveground and belowground biodiversity distributions and drivers of biodiversity change
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