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Shipman M, Tam J, Kim H, Schmitter-Edgecombe M. A-13Increasing Aging Services Technologies Awareness Through a Video-Based Intervention for Caregivers. Arch Clin Neuropsychol 2016. [DOI: 10.1093/arclin/acw043.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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2
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Carlson RP, Oshota O, Shipman M, Caserta JA, Hu P, Saunders CW, Xu J, Jay ZJ, Reeder N, Richards A, Pettigrew C, Peyton BM. Integrated molecular, physiological and in silico characterization of two Halomonas isolates from industrial brine. Extremophiles 2016; 20:261-74. [PMID: 26888357 DOI: 10.1007/s00792-015-0806-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 12/06/2015] [Indexed: 01/15/2023]
Abstract
Two haloalkaliphilic bacteria isolated from industrial brine solutions were characterized via molecular, physiological, and in silico metabolic pathway analyses. Genomes from the organisms, designated Halomonas BC1 and BC2, were sequenced; 16S ribosomal subunit-based phylogenetic analysis revealed a high level of similarity to each other and to Halomonas meridiana. Both strains were moderate halophiles with near optimal specific growth rates (≥60 % μ max) observed over <0.1-5 % (w/v) NaCl and pH ranging from 7.4 to 10.2. Isolate BC1 was further characterized by measuring uptake or synthesis of compatible solutes under different growth conditions; in complex medium, uptake and accumulation of external glycine betaine was observed while ectoine was synthesized de novo in salts medium. Transcriptome analysis of isolate BC1 grown on glucose or citrate medium measured differences in glycolysis- and gluconeogenesis-based metabolisms, respectively. The annotated BC1 genome was used to build an in silico, genome-scale stoichiometric metabolic model to study catabolic energy strategies and compatible solute synthesis under gradients of oxygen and nutrient availability. The theoretical analysis identified energy metabolism challenges associated with acclimation to high salinity and high pH. The study documents central metabolism data for the industrially and scientifically important haloalkaliphile genus Halomonas.
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Affiliation(s)
- Ross P Carlson
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA. .,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA.
| | - Olusegun Oshota
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,Department of Veterinary Medicine, University of Cambridge, Cambridge, UK
| | - Matt Shipman
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,U.S. Navy, Washington, DC, USA
| | | | - Ping Hu
- Procter and Gamble Co., Cincinnati, OH, 45202, USA
| | | | - Jun Xu
- Procter and Gamble Co., Cincinnati, OH, 45202, USA
| | - Zackary J Jay
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA
| | - Nancy Reeder
- Procter and Gamble Co., Cincinnati, OH, 45202, USA
| | - Abigail Richards
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA.,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA
| | | | - Brent M Peyton
- Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT, 59717, USA. .,Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA.
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Brawley SJ, Fayer SE, Shipman M, Laricchia G. Positronium Production and Scattering below Its Breakup Threshold. Phys Rev Lett 2015; 115:223201. [PMID: 26650302 DOI: 10.1103/physrevlett.115.223201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Indexed: 06/05/2023]
Abstract
Recent findings on the similarity between electron and positronium scattering at the same velocity [Brawley et al., Science 330, 789 (2010)] have guided us towards the realization of a detectable flux of positronium atoms at beam energies five times lower than previously obtained, enabling total cross sections to be measured in the energy range ∼(1-7) eV for the first time. In collision with Ar and Xe, the total cross sections of positronium are found to be smallest at the lowest energy probed, approaching those of the Ramsauer-Townsend minima for electron projectiles. Additional structure has been observed in the case of positronium scattering at incident energies around 5 eV.
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Affiliation(s)
- S J Brawley
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S E Fayer
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - M Shipman
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - G Laricchia
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Shipman M, Armitage S, Beale J, Brawley SJ, Fayer SE, Garner AJ, Leslie DE, Van Reeth P, Laricchia G. Absolute Differential Positronium-Formation Cross Sections. Phys Rev Lett 2015; 115:033401. [PMID: 26230792 DOI: 10.1103/physrevlett.115.033401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Indexed: 06/04/2023]
Abstract
The first absolute experimental determinations of the differential cross sections for the formation of ground-state positronium are presented for He, Ar, H2, and CO2 near 0°. Results are compared with available theories. The ratio of the differential and integrated cross sections for the targets exposes the higher propensity for forward emission of positronium formed from He and H2.
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Affiliation(s)
- M Shipman
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S Armitage
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - J Beale
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S J Brawley
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - S E Fayer
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - A J Garner
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - D E Leslie
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - P Van Reeth
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - G Laricchia
- UCL Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Winawer MR, Klassen TL, Teed S, Shipman M, Leung EH, Palmer AA. A locus on mouse Ch10 influences susceptibility to limbic seizure severity: fine mapping and in silico candidate gene analysis. Genes Brain Behav 2014; 13:341-9. [PMID: 24373497 DOI: 10.1111/gbb.12116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 11/19/2013] [Accepted: 12/16/2013] [Indexed: 11/29/2022]
Abstract
Identification of genes contributing to mouse seizure susceptibility can reveal novel genes or pathways that provide insight into human epilepsy. Using mouse chromosome substitution strains and interval-specific congenic strains (ISCS), we previously identified an interval conferring pilocarpine-induced limbic seizure susceptibility on distal mouse chromosome 10 (Ch10). We narrowed the region by generating subcongenics with smaller A/J Ch10 segments on a C57BL/6J (B6) background and tested them with pilocarpine. We also tested pilocarpine-susceptible congenics for 6-Hz ECT (electroconvulsive threshold), another model of limbic seizure susceptibility, to determine whether the susceptibility locus might have a broad effect on neuronal hyperexcitability across more than one mode of limbic seizure induction. The ISCS Line 1, which contained the distal 2.7 Mb segment from A/J (starting at rs29382217), was more susceptible to both pilocarpine and ECT. Line 2, which was a subcongenic of Line 1 (starting at rs13480828), was not susceptible, thus defining a 1.0 Mb critical region that was unique to Line 1. Bioinformatic approaches identified 45 human orthologs within the unique Line 1 susceptibility region, the majority syntenic to human Ch12. Applying an epilepsy network analysis of known and suspected excitability genes and examination of interstrain genomic and brain expression differences revealed novel candidates within the region. These include Stat2, which plays a role in hippocampal GABA receptor expression after status epilepticus, and novel candidates Pan2, Cdk2, Gls2 and Cs, which are involved in neural cell differentiation, cellular remodeling and embryonic development. Our strategy may facilitate discovery of novel human epilepsy genes.
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Affiliation(s)
- M R Winawer
- Department of Neurology; G.H. Sergievsky Center, Columbia University, New York, NY, USA
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Shipman M, Lubick K, Fouchard D, Gurram R, Grieco P, Jutila M, Dratz EA. Proteomic and systems biology analysis of the monocyte response to Coxiella burnetii infection. PLoS One 2013; 8:e69558. [PMID: 23990884 PMCID: PMC3749201 DOI: 10.1371/journal.pone.0069558] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 06/09/2013] [Indexed: 01/02/2023] Open
Abstract
Coxiella burnetii is an obligate intracellular bacterial pathogen and the causative agent of Q fever. Chronic Q fever can produce debilitating fatigue and C. burnetii is considered a significant bioterror threat. C. burnetii occupies the monocyte phagolysosome and although prior work has explained features of the host-pathogen interaction, many aspects are still poorly understood. We have conducted a proteomic investigation of human Monomac I cells infected with the Nine Mile Phase II strain of C. burnetii and used the results as a framework for a systems biology model of the host response. Our principal methodology was multiplex differential 2D gel electrophoresis using ZDyes, a new generation of covalently linked fluorescent protein detection dyes under development at Montana State University. The 2D gel analysis facilitated the detection of changes in posttranslational modifications on intact proteins in response to infection. The systems model created from our data a framework for the design of experiments to seek a deeper understanding of the host-pathogen interactions.
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Affiliation(s)
- Matt Shipman
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America
- * E-mail:
| | - Kirk Lubick
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
| | - David Fouchard
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America
| | - Rajani Gurram
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America
| | - Paul Grieco
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America
| | - Mark Jutila
- Department of Veterinary Molecular Biology, Montana State University, Bozeman, Montana, United States of America
| | - Edward A. Dratz
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America
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Aspray TJ, Jones EE, Davies MW, Shipman M, Bending GD. Increased hyphal branching and growth of ectomycorrhizal fungus Lactarius rufus by the helper bacterium Paenibacillus sp. Mycorrhiza 2013; 23:403-10. [PMID: 23397165 DOI: 10.1007/s00572-013-0483-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/29/2013] [Indexed: 05/03/2023]
Abstract
Paenibacillus sp. EJP73 has been previously demonstrated as a mycorrhization helper bacterium (MHB) for the Lactarius rufus-Pinus sylvestris symbiosis in both laboratory and glasshouse experiments. In the present study, the effect of Paenibacillus sp. EJP73 metabolites on L. rufus EO3 pre-symbiotic growth was tested in two agar plate-based systems. Specifically, volatile metabolites were investigated using a dual plate system, in which the presence of strain EJP73 resulted in a significant negative effect on L. rufus EO3 hyphal radial growth but enhanced hyphal branching and reduced internode distance. Soluble metabolites produced by strain EJP73 were tested on L. rufus EO3 growth in single-agar plate assays by incorporating bacterial cell-free whole or molecular weight fraction spent broth into the agar. Whole spent broth had a negative effect on hyphal growth, whereas a low molecular weight fraction (100-1,000) promoted colony radial growth. Headspace and spent broth analysis of strain EJP73 cultures revealed 2,5-diisopropylpyrazine to be the most significant component. Synthesised 2,5-diisopropylpyrazine and elevated CO2 (2,000 ppm) were tested as specific volatile metabolites in the dual plate system, but neither produced the response shown when strain EJP73 was present. Increased pre-symbiotic hyphal branching leading to increased likelihood of plant infection may be an important MHB mechanism for strain EJP73. Although the precise signal molecules could not be identified, the work suggests a number of metabolites may work synergistically to increase L. rufus root colonisation.
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Affiliation(s)
- T J Aspray
- School of Life Sciences, Heriot Watt University, Edinburgh, EH14 4AS Scotland, UK.
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Shipman M, Lubick K, Fouchard D, Guram R, Grieco P, Jutila M, Dratz EA. Proteomic and systems biology analysis of monocytes exposed to securinine, a GABA(A) receptor antagonist and immune adjuvant. PLoS One 2012; 7:e41278. [PMID: 23028424 PMCID: PMC3441550 DOI: 10.1371/journal.pone.0041278] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 06/19/2012] [Indexed: 11/18/2022] Open
Abstract
Securinine, a GABA(A) receptor antagonist, has been reported to enhance monocyte cell killing of Coxiella burnetii without obvious adverse effects in vivo. We employed multiplex 2D gel electrophoresis using Zdyes, a new generation of covalently linked fluorescent differential protein detection dyes to analyze changes in the monocyte proteome in response to Securinine. Securinine antagonism of GABA(A) receptors triggers the activation of p38. We used the differential protein expression results to guide a search of the literature and network analysis software to construct a systems biology model of the effect of Securinine on monocytes. The model suggests that various metabolic modulators (fatty acid binding protein 5, inosine 5'-monophosphate dehydrogenase, and thioredoxin) are at least partially reshaping the metabolic landscape within the monocytes. The actin bundling protein L-plastin, and the Ca(2+) binding protein S100A4 also appear to have important roles in the immune response stimulated by Securinine. Fatty acid binding protein 5 (FABP5) may be involved in effecting lipid raft composition, inflammation, and hormonal regulation of monocytes, and the model suggests that FABP5 may be a central regulator of metabolism in activated monocytes. The model also suggests that the heat shock proteins have a significant impact on the monocyte immune response. The model provides a framework to guide future investigations into the mechanisms of Securinine action and with elaboration may help guide development of new types of immune adjuvants.
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Affiliation(s)
- Matt Shipman
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, United States of America.
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Brawley SJ, Williams AI, Shipman M, Laricchia G. Resonant scattering of positronium in collision with CO2. Phys Rev Lett 2010; 105:263401. [PMID: 21231658 DOI: 10.1103/physrevlett.105.263401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2010] [Indexed: 05/30/2023]
Abstract
The total cross sections of positronium (Ps) scattering from a carbon-dioxide molecule have been measured over the range (7-400) eV incident-Ps energy. For the first time in Ps collisions, a resonantlike structure is observed. For the present target, it occurs around 9.5 eV followed by a broader peak at ∼60 eV. Following Brawley et al. [Science 330, 789 (2010)] who have observed similarities between the total cross sections of positronium and of electrons incident upon a given target at the same velocity, a corresponding comparison is made for CO2. The comparison suggests that the former peak corresponds to the well-known 2Π(u) shape resonance which occurs for electrons at an incident velocity of 0.5 a.u. Further features are discussed and theoretical input is sought.
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Affiliation(s)
- S J Brawley
- UCL Department of Physics and Astronomy, University College London, London, United Kingdom
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Shipman M, Paumier D, Garcia M, Muir JC. Rapid Assembly of the 1-Azabicyclo[3.1.0]hexane Skeleton of Ficellomycin. Synlett 2004. [DOI: 10.1055/s-2004-831313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hayes JF, Prévost N, Prokes I, Shipman M, Slawin AMZ, Twin H. Aziridinyl anions from a chiral, nonracemic 2-isopropylidineaziridine: surprisingly diastereoselective alkylation reactions. Chem Commun (Camb) 2003:1344-5. [PMID: 12841233 DOI: 10.1039/b303252c] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lithiation and alkylation of a 2-isopropylidineaziridine bearing an (S)-alpha-methylbenzyl group on nitrogen proceeds with high levels of diastereocontrol (80-90% de).
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Affiliation(s)
- J F Hayes
- GlaxoSmithKline, Old Powder Mills, Tonbridge, Kent, UK TN11 9AN
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Hayes JF, Shipman M, Twin H. Asymmetric synthesis of 2-substituted piperidines using a multi-component coupling reaction: rapid assembly of (S)-coniine from (S)-1-(1-phenylethyl)-2-methyleneaziridine. Chem Commun (Camb) 2001:1784-5. [PMID: 12240314 DOI: 10.1039/b106260n] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
(S)-Coniine is made using a reaction which assembles the piperidine ring by the sequential formation of four new chemical bonds and installs the C-2 stereogenic centre with high levels of diastereocontrol (90% de).
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Affiliation(s)
- J F Hayes
- GlaxoSmithKline, Old Powder Mills, Tonbridge, Kent, UK TN11 9AN
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Prévost N, Shipman M. Intramolecular radical rearrangement reactions of 2-methyleneaziridines: application to the synthesis of substituted piperidines, decahydroquinolines, and octahydroindolizines. Org Lett 2001; 3:2383-5. [PMID: 11463322 DOI: 10.1021/ol016194k] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] Intramolecular 5-exo cyclization of 3-(2-methyleneaziridin-1-yl)propyl radicals leads to the generation of a highly strained, bicyclic aziridinylcarbinyl radical that undergoes C-N bond fission to the ring-expanded aminyl radical. This methodology provides access to substituted 3-methylenepiperidines and, by combining it with an additional 5-exo-trig cyclization reaction, the octahydroindolizidine skeleton.
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Affiliation(s)
- N Prévost
- School of Chemistry, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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Grimson MJ, Coates JC, Reynolds JP, Shipman M, Blanton RL, Harwood AJ. Adherens junctions and beta-catenin-mediated cell signalling in a non-metazoan organism. Nature 2000; 408:727-31. [PMID: 11130075 DOI: 10.1038/35047099] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mechanical forces between cells have a principal role in the organization of animal tissues. Adherens junctions are an important component of these tissues, connecting cells through their actin cytoskeleton and allowing the assembly of tensile structures. At least one adherens junction protein, beta-catenin, also acts as a signalling molecule, directly regulating gene expression. To date, adherens junctions have only been detected in metazoa, and therefore we looked for them outside the animal kingdom to examine their evolutionary origins. The non-metazoan Dictyostelium discoideum forms a multicellular, differentiated structure. Here we describe the discovery of actin-associated intercellular junctions in Dictyostelium. We have isolated a gene encoding a beta-catenin homologue, aardvark, which is a component of the junctional complex, and, independently, is required for cell signalling. Our discovery of adherens junctions outside the animal kingdom shows that the dual role of beta-catenin in cell-cell adhesion and cell signalling evolved before the origins of metazoa.
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Affiliation(s)
- M J Grimson
- Dept of Biological Sciences, Texas Tech University, Lubbock 79409, USA
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Abstract
We report on a patient with a low testosterone level which occurred during treatment with venlafaxine. The testosterone level increased when the medication was discontinued. Possible clinical correlation with amelioration of paraphilia is discussed.
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Hodgkinson TJ, Kelland LR, Shipman M, Suzenet F. Chemical synthesis and cytotoxicity of some azinomycin analogues devoid of the 1-azabicyclo[3.1.0]hexane subunit. Bioorg Med Chem Lett 2000; 10:239-41. [PMID: 10698444 DOI: 10.1016/s0960-894x(99)00663-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A series of compounds related to the left-hand domain of the azinomycins have been made and evaluated for cytotoxic activity against a small panel of human tumour cell lines. The epoxide ring is shown to be essential for biological activity. Cytotoxicity is also shown to be sensitive to changes in the substitution pattern on the aromatic ring and the amide group.
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Gibson A, Futter CE, Maxwell S, Allchin EH, Shipman M, Kraehenbuhl JP, Domingo D, Odorizzi G, Trowbridge IS, Hopkins CR. Sorting mechanisms regulating membrane protein traffic in the apical transcytotic pathway of polarized MDCK cells. J Cell Biol 1998; 143:81-94. [PMID: 9763422 PMCID: PMC2132803 DOI: 10.1083/jcb.143.1.81] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/1998] [Revised: 07/29/1998] [Indexed: 02/01/2023] Open
Abstract
The transcytotic pathway followed by the polymeric IgA receptor (pIgR) carrying its bound ligand (dIgA) from the basolateral to the apical surface of polarized MDCK cells has been mapped using morphological tracers. At 20 degreesC dIgA-pIgR internalize to interconnected groups of vacuoles and tubules that comprise the endosomal compartment and in which they codistribute with internalized transferrin receptors (TR) and epidermal growth factor receptors (EGFR). Upon transfer to 37 degreesC the endosome vacuoles develop long tubules that give rise to a distinctive population of 100-nm-diam cup-shaped vesicles containing pIgR. At the same time, the endosome gives rise to multivesicular endosomes (MVB) enriched in EGFR and to 60-nm-diam basolateral vesicles. The cup-shaped vesicles carry the dIgA/pIgR complexes to the apical surface where they exocytose. Using video microscopy and correlative electron microscopy to study cells grown thin and flat we show that endosome vacuoles tubulate in response to dIgA/pIgR but that the tubules contain TR as well as pIgR. However, we show that TR are removed from these dIgA-induced tubules via clathrin-coated buds and, as a result, the cup-shaped vesicles to which the tubules give rise become enriched in dIgA/pIgR. Taken together with the published information available on pIgR trafficking signals, our observations suggest that the steady-state concentrations of TR and unoccupied pIgR on the basolateral surface of polarized MDCK cells are maintained by a signal-dependent, clathrin-based sorting mechanism that operates along the length of the transcytotic pathway. We propose that the differential sorting of occupied receptors within the MDCK endosome is achieved by this clathrin-based mechanism continuously retrieving receptors like TR from the pathways that deliver pIgR to the apical surface and EGFR to the lysosome.
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Affiliation(s)
- A Gibson
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, WC1E 6BT London, United Kingdom
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Hopkins CR, Gibson A, Shipman M, Strickland DK, Trowbridge IS. In migrating fibroblasts, recycling receptors are concentrated in narrow tubules in the pericentriolar area, and then routed to the plasma membrane of the leading lamella. J Cell Biol 1994; 125:1265-74. [PMID: 7515888 PMCID: PMC2290921 DOI: 10.1083/jcb.125.6.1265] [Citation(s) in RCA: 215] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
By following the intracellular processing of recycling transferrin receptors and the selective sorting of a-2 macroglobulin in chick embryo fibroblasts, we have shown that the concentration of 60 nm diam tubules which surrounds the centrioles represents a distal compartment on the recycling pathway. In migrating cells transferrin receptor tracers can be loaded into this compartment and then chased to the cell surface. When they emerge the recycling transferrin receptors are distributed over the surface of the leading lamella.
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Affiliation(s)
- C R Hopkins
- Laboratory of Molecular Cell Biology, University College, London, United Kingdom
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19
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Abstract
Gold conjugates have been used to quantitate human transferrin receptors (hTfnRs) on transfected chick embryo fibroblasts. No relationship could be found between the number of hTfnRs and the number of clathrin-coated pits. However, hTfnRs are also associated with flat clathrin lattices that lie outside invaginated pits. With increasing levels of receptor expression, the density of hTfnRs within flat lattices increases, and at the highest levels of expression the total area of flat lattice increases up to 3-fold. These results show that increased receptor numbers can promote clathrin lattice growth and suggest that the recruitment of receptors like hTfnRs is an essential step in lattice construction. We conclude that the process of invagination, which gives rise to coated pits, is regulated separately.
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Affiliation(s)
- K Miller
- Department of Biochemistry, Imperial College, London, England
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Abstract
Complexes of cell-surface receptors and their ligands are commonly internalized by endocytosis and enter a prelysosomal endosomal pathway for further processing. Fluorescence microscopy and video recording of living cells to trace the passage of ligand-receptor complexes has identified the endosomal compartment as an extensive network of tubular cisternae. Endocytosed material entering this reticulum enters discrete swellings, identified as multivesicular bodies by electron microscopy, which move along the reticulum towards the pericentriolar area.
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Affiliation(s)
- C R Hopkins
- Department of Biochemistry, Imperial College, London, UK
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