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Liu Y, Kwok W, Yoon H, Ryu JC, Stevens P, Hawkinson TR, Shedlock CJ, Ribas RA, Medina T, Keohane SB, Scharre D, Bruschweiler-Li L, Bruschweiler R, Gaultier A, Obrietan K, Sun RC, Yoon SO. Imbalance in Glucose Metabolism Regulates the Transition of Microglia from Homeostasis to Disease-Associated Microglia Stage 1. J Neurosci 2024; 44:e1563232024. [PMID: 38565291 PMCID: PMC11097271 DOI: 10.1523/jneurosci.1563-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 03/21/2024] [Accepted: 03/23/2024] [Indexed: 04/04/2024] Open
Abstract
Microglia undergo two-stage activation in neurodegenerative diseases, known as disease-associated microglia (DAM). TREM2 mediates the DAM2 stage transition, but what regulates the first DAM1 stage transition is unknown. We report that glucose dyshomeostasis inhibits DAM1 activation and PKM2 plays a role. As in tumors, PKM2 was aberrantly elevated in both male and female human AD brains, but unlike in tumors, it is expressed as active tetramers, as well as among TREM2+ microglia surrounding plaques in 5XFAD male and female mice. snRNAseq analyses of microglia without Pkm2 in 5XFAD mice revealed significant increases in DAM1 markers in a distinct metabolic cluster, which is enriched in genes for glucose metabolism, DAM1, and AD risk. 5XFAD mice incidentally exhibited a significant reduction in amyloid pathology without microglial Pkm2 Surprisingly, microglia in 5XFAD without Pkm2 exhibited increases in glycolysis and spare respiratory capacity, which correlated with restoration of mitochondrial cristae alterations. In addition, in situ spatial metabolomics of plaque-bearing microglia revealed an increase in respiratory activity. These results together suggest that it is not only glycolytic but also respiratory inputs that are critical to the development of DAM signatures in 5XFAD mice.
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Affiliation(s)
- Yuxi Liu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio 43210
| | - Witty Kwok
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio 43210
| | - Hyojung Yoon
- Department of Neuroscience, The Ohio State University, Columbus, Ohio 43210
| | - Jae Cheon Ryu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio 43210
| | - Patrick Stevens
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio 43210
| | - Tara R Hawkinson
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida 32610
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, Florida, 32610
| | - Cameron J Shedlock
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida 32610
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, Florida, 32610
| | - Roberto A Ribas
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida 32610
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, Florida, 32610
| | - Terrymar Medina
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida 32610
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, Florida, 32610
| | - Shannon B Keohane
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida 32610
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, Florida, 32610
| | - Douglas Scharre
- Department of Neurology, The Ohio State University, Columbus, Ohio 43210
| | - Lei Bruschweiler-Li
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Rafael Bruschweiler
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Alban Gaultier
- Center for Brain Immunology and Glia, University of Virginia, Charlottesville, Virginia, 22908
| | - Karl Obrietan
- Department of Neuroscience, The Ohio State University, Columbus, Ohio 43210
| | - Ramon C Sun
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida 32610
- Center for Advanced Spatial Biomolecule Research, University of Florida, Gainesville, Florida, 32610
| | - Sung Ok Yoon
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio 43210
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Au S, Bellato V, Carvas JM, Córdoba CD, Daudu D, Dziakova J, Eltarhoni K, El Feituri N, Fung ACH, Fysaraki C, Gallo G, Gultekin FA, Harbjerg JL, Hatem F, Ioannidis A, Jakobsen L, Clinch D, Kristensen HØ, Kuiper SZ, Kwok AMF, Kwok W, Millan M, Milto KM, Ng HJ, Pellino G, Picciariello A, Pronin S, van Ramshorst GH, Ramser M, Jiménez-Rodríguez RM, Sainz Hernandez JC, Samadov E, Sohrabi S, Uchiyama M, Wang JHS, Younis MU, Fleming S, Alhomoud S, Mayol J, Moeslein G, Smart NJ, Soreide K, Teh C, Verran D, Maeda Y. Global parental leave in surgical careers: differences according to gender, geographical regions and surgical career stages. Br J Surg 2021; 108:1315-1322. [PMID: 34467970 DOI: 10.1093/bjs/znab275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 03/24/2021] [Accepted: 07/01/2021] [Indexed: 11/12/2022]
Abstract
BACKGROUND There is a lack of information regarding the provision of parental leave for surgical careers. This survey study aims to evaluate the experience of maternity/paternity leave and views on work-life balance globally. METHODS A 55-item online survey in 24 languages was distributed via social media as per CHERRIES guideline from February to March 2020. It explored parental leave entitlements, attitude towards leave taking, financial impact, time spent with children and compatibility of parenthood with surgical career. RESULTS Of the 1393 (male : female, 514 : 829) respondents from 65 countries, there were 479 medical students, 349 surgical trainees and 513 consultants. Consultants had less than the recommended duration of maternity leave (43.8 versus 29.1 per cent), no paid maternity (8.3 versus 3.2 per cent) or paternity leave (19.3 versus 11.0 per cent) compared with trainees. Females were less likely to have children than males (36.8 versus 45.6 per cent, P = 0.010) and were more often told surgery is incompatible with parenthood (80.2 versus 59.5 per cent, P < 0.001). Males spent less than 20 per cent of their salary on childcare and fewer than 30 hours/week with their children. More than half (59.2 per cent) of medical students did not believe a surgical career allowed work-life balance. CONCLUSION Surgeons across the globe had inadequate parental leave. Significant gender disparity was seen in multiple aspects.
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Affiliation(s)
- S Au
- NHS Education for Scotland, Edinburgh, UK
| | | | | | - C D Córdoba
- University of Lausanne, Lausanne, Switzerland
| | - D Daudu
- Faculty of Health and Medical Sciences, University of Western Australia, Australia
| | - J Dziakova
- Hospital Clinico San Carlos, IDISSC, Madrid, Spain
| | | | | | - A C H Fung
- Department of Surgery, The University of Hong Kong, Hong Kong SAR, China
| | - C Fysaraki
- Urology Department, Mid Yorkshire Hospitals NHS Trust, UK
| | - G Gallo
- Department of Medical and Surgical Sciences, University of Catanzaro, Catanzaro, Italy
| | - F Ayca Gultekin
- General Surgery Department, Zonguldak Bulent, Ecevit University School of Medicine, Zonguldak, Turkey
| | - J L Harbjerg
- Department of Surgery, Research Unit C119, Aarhus University Hospital, Palle Juul-Jensens, Aarhus N, Denmark
| | - F Hatem
- Glasgow Royal Infirmary, Glasgow, UK
| | | | - L Jakobsen
- UiT, The Arctic University of Norway, University Hospital of North Norway, Tromso, Norway
| | - D Clinch
- Department of General Surgery, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - H Ø Kristensen
- Department of Surgery, Research Unit C119, Aarhus University Hospital, Palle Juul-Jensens, Aarhus N, Denmark
| | - S Z Kuiper
- School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands
| | | | - W Kwok
- Royal Infirmary of Edinburgh, Edinburgh, UK
| | - M Millan
- Coloproctology Unit, Department of Surgery, La Fe University Hospital, Valencia, Spain
| | - K M Milto
- NHS Education for Scotland, Edinburgh, UK
| | - H J Ng
- Royal Alexandra Hospital, NHS Greater Glasgow and Clyde, UK
| | - G Pellino
- Department of Advanced Medical and Surgical Sciences, Università degli Studi della Campania 'Luigi Vanvitelli', Naples, Italy
| | - A Picciariello
- Department of Emergency and Organ Transplantation, University 'Aldo Moro' of Bari, Italy
| | - S Pronin
- College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, UK
| | | | - M Ramser
- Department of Surgery, Solothurner Spitäler SoH, Bürgerspital Solothurn, Solothurn, Switzerland
| | | | - J C Sainz Hernandez
- Instituto Nacional de Ciencias Médicas y Nutrición 'Salvador Zubirán', Mexico City, Mexico
| | - E Samadov
- Surgical Department, LEYLA Medical Centre, Baku, Azerbaijan
| | | | - M Uchiyama
- Showa University School of Medicine, Tokyo, Japan
| | - J H-S Wang
- Australasian Students' Surgical Association, New Zealand
| | - M U Younis
- Mediclinic City Hospital, Dubai, United Arab Emirates
| | - S Fleming
- Barts and the London School of Medicine and Dentistry, London, UK
| | - S Alhomoud
- King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia
| | - J Mayol
- Hospital Clinico San Carlos, Instituto de Investigación Sanitaria San Carlos, Universidad Complutense, Madrid, Spain
| | - G Moeslein
- Ev. Bethesda Khs Duisburg, University of Witten, Herdecke, Germany
| | - N J Smart
- Royal Devon & Exeter Hospital & University of Exeter Medical School, Exeter, UK
| | - K Soreide
- Department of Gastrointestinal Surgery, Stavanger University Hospital, Stavanger, Norway
| | - C Teh
- Department of Surgery, Makati Medical Centre, Makati, Philippines.,Department of General Surgery, National Kidney & Transplant Institute, Quezon City, Philippines
| | - D Verran
- Ramsey Health Care, Sydney, Australia
| | - Y Maeda
- Department of Colorectal Surgery, Western General Hospital and University of Edinburgh, Edinburgh, UK
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Jeong D, Robinson D, Kwok W. Jug r 1 and Jug r 2-specific CD4+ T-Cells: Epitope Mapping, Ex Vivo Characterization, and Phenotype Analysis. J Allergy Clin Immunol 2011. [DOI: 10.1016/j.jaci.2010.12.640] [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: 11/28/2022]
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Phillips D, Fang W, Zheng X, Li Y, Wang D, Kwok W. Isopolyhalomethanes: Their Formation, Structures, Properties and Cyclopropanation Reactions with Olefins. CURR ORG CHEM 2004. [DOI: 10.2174/1385272043370483] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Kwok W, Miller S. Debromination vs Dehydrobromination of meso- and dl-Stilbene Dibromides by Lithium Chloride, Potassium Fluoride, and Dimehtylformamide in Dimethylformamide. A Halogen Nucleophilicity Scale. J Org Chem 2003. [DOI: 10.1021/jo00837a705] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
The present study was intended to examine the relaxant effects of berberine in rat isolated mesenteric arteries. Berberine produced a rightward shift of the concentration-response curve to phenylephrine and significantly reduced the maximal contractile response to phenylephrine. Berberine (10(-7)-3x10(-5) M) also relaxed the phenylephrine- and 9,11-dideoxy-11alpha, 9alpha-epoxy-methanoprostaglandin F(2alpha)-precontracted arteries with respective IC(50) values of 1.48+/-0.16x10(-6) and 2.23+/-0. 22x10(-6) M. Removal of a functional endothelium significantly attenuated the berberine-induced relaxation (IC(50): 4.73+/-0. 32x10(-6) M) without affecting the maximum relaxant response. Pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME) or methylene blue reduced the relaxant effect of berberine, and L-arginine (10(-3) M) partially antagonized the effect of L-NAME. In contrast, pretreatment with 10(-6) M glibenclamide or 10(-5) M indomethacin had no effect. Berberine (10(-5) M) reduced over by 50% the transient contraction induced by caffeine or phenylephrine in endothelium-denuded rings bathed in Ca(2+)-free Krebs solution. Pretreatment with putative K(+) channel blockers, such as tetrapentylammonium ions (1-3x10(-6) M), 4-aminopyridine (10(-3) M), or Ba(2+) (3x10(-4) M), significantly attenuated the berberine-induced relaxation in endothelium-denuded arteries. In contrast, tetraethylammonium ions (3x10(-3) M), charybdotoxin (10(-7) M) or glibenclamide (10(-6) M) were without effect. Berberine reduced the high-K(+)-induced sustained contraction and the relaxant response to berberine was greater in rings with endothelium (IC(50): 4.41+/-0.47x10(-6) M) than in those without endothelium (IC(50): 8.73+/-0.74x10(-6) M). However, berberine (10(-6)-10(-4) M) did not affect the high-K(+)-induced increase of intracellular [Ca(2+)] in cultured aortic smooth muscle cells. Berberine did not affect active phorbol ester-induced contraction in Ca(2+)-free Krebs solution. In addition, berberine inhibited proliferation of cultured rat aortic smooth muscle cells with an IC(50) of 2.3+/-0.43x10(-5) M. These findings suggest that berberine could act at both endothelium and the underlying vascular smooth muscle to induce relaxation. Nitric oxide from endothelium may account primarily for the berberine-induced endothelium-dependent relaxation, while activation of tetrapentylammonium-, 4-aminopyridine- and Ba(2+)-sensitive K(+) channels, inhibition of intracellular Ca(2+) release from caffeine-sensitive pools, or a direct relaxant effect, is likely responsible for the berberine-induced endothelium-independent relaxation. Mechanisms related to either Ca(2+) influx or protein kinase C activation may not be involved. Both vasorelaxant and antiproliferative effects may contribute to a long-term benefit of berberine in the vascular system.
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MESH Headings
- Animals
- Aorta/cytology
- Berberine/pharmacology
- Calcimycin/pharmacology
- Calcium/metabolism
- Calcium/pharmacology
- Cell Division/drug effects
- Cells, Cultured
- Dose-Response Relationship, Drug
- In Vitro Techniques
- Male
- Mesenteric Artery, Superior/drug effects
- Mesenteric Artery, Superior/physiology
- Methylene Blue/pharmacology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- NG-Nitroarginine Methyl Ester/pharmacology
- Phorbol Esters/pharmacology
- Potassium/pharmacology
- Potassium Channel Blockers
- Rats
- Rats, Sprague-Dawley
- Vasoconstriction/drug effects
- Vasodilation/drug effects
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Affiliation(s)
- W H Ko
- Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, Hong Kong, People's Republic of China
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Aranson IS, Blair D, Kalatsky VA, Crabtree GW, Kwok W, Vinokur VM, Welp U. Electrostatically driven granular media: phase transitions and coarsening. Phys Rev Lett 2000; 84:3306-3309. [PMID: 11019076 DOI: 10.1103/physrevlett.84.3306] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/1999] [Revised: 01/05/2000] [Indexed: 05/23/2023]
Abstract
We report the experimental and theoretical study of electrostatically driven granular material. We show that the charged granular medium undergoes a hysteretic phase transition from the immobile condensed state (granular solid) to a fluidized dilated state (granular gas) with a changing applied electric field. In addition we observe a spontaneous precipitation of dense clusters from the gas phase and subsequent coarsening-coagulation of these clusters. Molecular dynamics simulations show qualitative agreement with experimental results.
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Affiliation(s)
- IS Aranson
- Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA
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Scalettar RT, Zimanyi GT, Olsson R, Petrean A, Kwok W, Vinokur V. Dynamic phases and the peak effect in dirty type II superconductors. Phys Rev Lett 2000; 84:2493-2496. [PMID: 11018918 DOI: 10.1103/physrevlett.84.2493] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/1998] [Revised: 05/11/1999] [Indexed: 05/23/2023]
Abstract
We study numerically and experimentally the dynamics of driven vortex matter. Our London-Langevin simulations find that the critical current exhibits a peak both across the Bragg glass to vortex glass transition and across the melting line. The peak is accompanied by a clear crossing of the I-V curves. We report transport measurements on untwinned YBCO crystals, in complete accordance with these findings. At higher drives disorder is averaged to reduced values, and in three dimensions the vortices reorder into a "moving solid." The effect of the disorder can be well represented with a "shaking temperature" which is inversely proportional to the velocity.
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Yamaguchi M, McSweeney PA, Kimball L, Gersuk G, Hong DS, Kwok W, Storb R, Beckham C, Deeg HJ. Recognition of major histocompatibility complex class II antigens by two anti-HLA-DR monoclonal antibodies on canine marrow cells correlates with effects on in vitro and in vivo hematopoiesis. Transplantation 1999; 68:1161-71. [PMID: 10551646 DOI: 10.1097/00007890-199910270-00017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The role of major histocompatibility complex class II antigens in hematopoiesis is not well defined. We have shown that in vitro depletion of HLA-DR+ cells from canine marrow (e.g., by anti-HLA-DR monoclonal antibody [mAb] H81.9 and complement) prevents hematopoietic recovery. In vivo administration of the same mAb H81.9 after transplantation of unmanipulated autologous marrow results in graft failure. In vitro mAb H81.9 inhibited colony formation from short-term and long-term marrow cultures. METHODS AND RESULTS We investigated the effect of another mAb, Ca1.41, which also recognizes nonpolymorphic determinants on human (HLA-DR) and canine major histocompatibility complex class II antigens but is reactive with a narrower spectrum of cells in both canine peripheral blood and marrow than mAb H81.9 (and other anti-HLA-DR mAbs). In contrast to all other anti-HLA-DR mAbs tested, Ca1.41 did not interfere with colony formation in short-term or long-term marrow cultures and spared a population of small mononuclear cells with low forward light scatter that was eliminated via apoptosis by exposure to mAb H81.9. These target cells included lymphocytes and CD34+ hemopoietic precursors that expressed MHC class II molecules as determined by mAb H81.9 but not by mAb Ca1.41. In addition, transmembrane signaling and up-regulation of interleukin-1beta mRNA occurred with mAb H81.9 but not with Ca1.41. Transplantation of autologous marrow treated in vitro cytolytically with mAb Ca1.41 allowed for complete hematopoietic reconstitution. Further, in vivo administration of Ca1.41 posttransplant did not lead to autologous graft failure as had been observed with mAb H81.9. CONCLUSIONS These results support the notion that major histocompatibility complex class II is expressed on early hematopoietic precursor cells but recognition is dependent upon the mAb used. Preliminary studies show that mAb H81.9 triggered transmembrane signaling, resulting in up-regulation of interleukin-1beta and apoptosis, although mAb Ca1.41 did not. The fact that Ca1.41 binding was modified in the presence of exogenous invariant chain-derived peptide suggests that both binding and signaling are peptide dependent.
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Affiliation(s)
- M Yamaguchi
- Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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Affiliation(s)
- H Noorchashm
- University of Pennsylvania Hospital, Philadelphia, Pennsylvania, USA
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Abstract
An algorithm for lost signal restoration in block-based still image and video sequence coding is presented. Problems arising from imperfect transmission of block-coded images result in lost blocks. The resulting image is flawed by the absence of square pixel regions that are notably perceived by human vision, even in real-time video sequences. Error concealment is aimed at masking the effect of missing blocks by use of temporal or spatial interpolation to create a subjectively acceptable approximation to the true error-free image. This paper presents a spatial interpolation algorithm that addresses concealment of lost image blocks using only intra-frame information. It attempts to utilize spatially correlated edge information from a large local neighborhood of surrounding pixels to restore missing blocks. The algorithm is a Gerchberg (1974) type spatial domain/spectral domain constraint-satisfying iterative process, and may be viewed as an alternating projections onto convex sets method.
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Affiliation(s)
- H Sun
- David Sarnoff Res. Center, Princeton, NJ
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Abstract
The prune locus of Drosophila melanogaster lies at the tip of the X chromosome, in a region of reduced recombination in which nearby loci show reduced variation relative to evolutionary divergence from D. simulans. DNA sequencing of prune alleles from D. melanogaster and D. simulans reveals extremely low variation in D. melanogaster but greater variation in D. simulans. Divergence between the two species is not reduced. This pattern may be explained by either positive selection leading to hitchhiking of neutral variation or background selection against deleterious mutations. The pattern of silent versus replacement polymorphism and divergence at prune is consistent with either a model of weakly deleterious selection against amino acid substitutions or balancing selection.
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Affiliation(s)
- G M Simmons
- Department of Biology, City College, City University of New York, New York 10031
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Abstract
The use of conventional ultrasound systems to image the upper airway has been limited because ultrasound energy is attenuated by the air column. In an attempt to study upper airway geometry, we developed a computer controlled bi-directional ultrasound system which combines two conventional ultrasound devices with computer image processing to yield images of upper airway structures. Human studies and cadaver studies were performed to evaluate the system. Images acquired by the bi-directional ultrasound system were comparable to images from 3D volume rendered CT scans. This system may provide valuable data in the study of upper airway physiology and pathology.
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Affiliation(s)
- W Kwok
- Department of Surgery, Milton S. Hershey Medical Center, Pennsylvania State University, College of Medicine, PA 17033
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Abstract
Non-paired nucleotides stabilize the formation of three-way helical DNA junctions. Two or more unpaired nucleotides located in the junction region enable oligomers ten to fifteen nucleotides long to assemble, forming conformationally homogeneous junctions, as judged by native gel electrophoresis. The unpaired bases can be present on the same strand or on two different strands. Up to five extra bases on one strand have been tested and found to produce stable junctions. The formation of stable structures is favored by the presence of a divalent cation such as magnesium and by high monovalent salt concentration. The order-disorder transition of representative three-way junctions was monitored optically in the ultraviolet and analyzed to quantify thermodynamically the stabilization provided by unpaired bases in the junction region. We report the first measurements of the thermodynamics of adding an unpaired nucleotide to a nucleic acid three-way junction. We find that delta delta G degrees (37 degrees C) = +0.5 kcal/mol for increasing the number of unpaired adenosines from two to three. Three-way junctions having reporter arms 40 base-pairs long were also prepared. Each of the three reporter arms contained a unique restriction site 15 base-pairs from the junction. Asymmetric complexes produced by selectively cleaving each arm were analyzed on native gels. Cleavage of the double helical arm opposite the strand having the two extra adenosines resulted in a complex that migrated more slowly than complexes produced by cleavage at either of the other two arms. It is likely that the strand containing the unpaired adenosines is kinked at an acute angle, forming a Y-shaped, rather than a T-shaped junction.
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Affiliation(s)
- N B Leontis
- Department of Chemistry, Bowling Green State University, OH 43403
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Simpson RB, O'Hara PJ, Kwok W, Montoya AL, Lichtenstein C, Gordon MP, Nester EW. DNA from the A6S/2 crown gall tumor contains scrambled Ti-plasmid sequences near its junctions with plant DNA. Cell 1982; 29:1005-14. [PMID: 7151163 DOI: 10.1016/0092-8674(82)90464-0] [Citation(s) in RCA: 105] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The A6S/2 tumor incited on tobacco by Agrobacterium tumefaciens harboring the octopine-type A6 Ti plasmid contains one insert of Ti-plasmid sequences (the T DNA). This 13 kb insert is derived from a colinear sequence in the Ti plasmid (the T region) and becomes attached to plant DNA in the nucleus of the host cell. We have determined the DNA sequence encompassing the left end of the T region of the A6 Ti plasmid and the corresponding portion of the A6S/2 T DNA. The two sequences are identical for at least 806 bp. To the left of the divergence point, the tumor contains five partially overlapping sequences that are direct or inverted repeats of sequences to the right of the divergence point. The Ti plasmid contains only the right member of each of these repeats. We have also performed heteroduplex studies that indicate that this T DNA has a 520 bp inverted repeat of an internal sequence at the right end near its junction with plant DNA. The repeated sequences near the ends of the T DNA resemble the repeats of adenovirus type 12 sequences found near its junction with host DNA. We discuss data suggesting that the 23 bp to the immediate right of the divergence point of the A6 left junction form a site important in some step in the transfer of T-region DNA from the bacteria to the plant.
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Kwok W, Lee W, Miller S. Additions and Corrections - The Kinetics, Isotope Rate Effect, and Mechanisms of Dehydrobromination of cis-1,2-Dibromoethylene with Triethylamine in Dimethylformamide. J Am Chem Soc 1972. [DOI: 10.1021/ja00766a601] [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: 11/28/2022]
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