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  • 1
    Publication Date: 2011-04-23
    Description: Mucosal surfaces constantly encounter microbes. Toll-like receptors (TLRs) mediate recognition of microbial patterns to eliminate pathogens. By contrast, we demonstrate that the prominent gut commensal Bacteroides fragilis activates the TLR pathway to establish host-microbial symbiosis. TLR2 on CD4(+) T cells is required for B. fragilis colonization of a unique mucosal niche in mice during homeostasis. A symbiosis factor (PSA, polysaccharide A) of B. fragilis signals through TLR2 directly on Foxp3(+) regulatory T cells to promote immunologic tolerance. B. fragilis lacking PSA is unable to restrain T helper 17 cell responses and is defective in niche-specific mucosal colonization. Therefore, commensal bacteria exploit the TLR pathway to actively suppress immunity. We propose that the immune system can discriminate between pathogens and the microbiota through recognition of symbiotic bacterial molecules in a process that engenders commensal colonization.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164325/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3164325/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Round, June L -- Lee, S Melanie -- Li, Jennifer -- Tran, Gloria -- Jabri, Bana -- Chatila, Talal A -- Mazmanian, Sarkis K -- AI 080002/AI/NIAID NIH HHS/ -- AI 088626/AI/NIAID NIH HHS/ -- DK 078938/DK/NIDDK NIH HHS/ -- DK 083633/DK/NIDDK NIH HHS/ -- R01 AI085090/AI/NIAID NIH HHS/ -- R01 AI085090-01/AI/NIAID NIH HHS/ -- R01 AI085090-01S1/AI/NIAID NIH HHS/ -- R01 AI085090-02/AI/NIAID NIH HHS/ -- R01 AI085090-03/AI/NIAID NIH HHS/ -- R01 DK078938/DK/NIDDK NIH HHS/ -- R01 DK078938-01A2/DK/NIDDK NIH HHS/ -- R01 DK078938-02/DK/NIDDK NIH HHS/ -- R01 DK078938-03/DK/NIDDK NIH HHS/ -- R01 DK078938-04/DK/NIDDK NIH HHS/ -- R21 AI080002/AI/NIAID NIH HHS/ -- R21 AI080002-01/AI/NIAID NIH HHS/ -- R21 AI080002-02/AI/NIAID NIH HHS/ -- R21 AI088626/AI/NIAID NIH HHS/ -- R21 AI088626-01/AI/NIAID NIH HHS/ -- R21 AI088626-02/AI/NIAID NIH HHS/ -- R21 DK083633/DK/NIDDK NIH HHS/ -- R21 DK083633-01A1/DK/NIDDK NIH HHS/ -- R21 DK083633-02/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 2011 May 20;332(6032):974-7. doi: 10.1126/science.1206095. Epub 2011 Apr 21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA. jround@caltech.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21512004" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bacteroides fragilis/*growth & development/*immunology ; Colon/immunology/microbiology ; Germ-Free Life ; Homeostasis ; Humans ; *Immune Tolerance ; Immunity, Mucosal ; Interleukin-10/metabolism ; Intestinal Mucosa/*immunology/*microbiology ; Metagenome ; Mice ; Mice, Inbred C57BL ; Models, Biological ; Polysaccharides, Bacterial/immunology/*metabolism ; Signal Transduction ; Specific Pathogen-Free Organisms ; Symbiosis ; T-Lymphocytes, Regulatory/immunology ; Th17 Cells/immunology ; Toll-Like Receptor 2/immunology/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2013-08-21
    Description: Mammals harbour a complex gut microbiome, comprising bacteria that confer immunological, metabolic and neurological benefits. Despite advances in sequence-based microbial profiling and myriad studies defining microbiome composition during health and disease, little is known about the molecular processes used by symbiotic bacteria to stably colonize the gastrointestinal tract. We sought to define how mammals assemble and maintain the Bacteroides, one of the most numerically prominent genera of the human microbiome. Here we find that, whereas the gut normally contains hundreds of bacterial species, germ-free mice mono-associated with a single Bacteroides species are resistant to colonization by the same, but not different, species. To identify bacterial mechanisms for species-specific saturable colonization, we devised an in vivo genetic screen and discovered a unique class of polysaccharide utilization loci that is conserved among intestinal Bacteroides. We named this genetic locus the commensal colonization factors (ccf). Deletion of the ccf genes in the model symbiont, Bacteroides fragilis, results in colonization defects in mice and reduced horizontal transmission. The ccf genes of B. fragilis are upregulated during gut colonization, preferentially at the colonic surface. When we visualize microbial biogeography within the colon, B. fragilis penetrates the colonic mucus and resides deep within crypt channels, whereas ccf mutants are defective in crypt association. Notably, the CCF system is required for B. fragilis colonization following microbiome disruption with Citrobacter rodentium infection or antibiotic treatment, suggesting that the niche within colonic crypts represents a reservoir for bacteria to maintain long-term colonization. These findings reveal that intestinal Bacteroides have evolved species-specific physical interactions with the host that mediate stable and resilient gut colonization, and the CCF system represents a novel molecular mechanism for symbiosis.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893107/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893107/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lee, S Melanie -- Donaldson, Gregory P -- Mikulski, Zbigniew -- Boyajian, Silva -- Ley, Klaus -- Mazmanian, Sarkis K -- DK078938/DK/NIDDK NIH HHS/ -- GM007616/GM/NIGMS NIH HHS/ -- GM099535/GM/NIGMS NIH HHS/ -- P01 DK091222/DK/NIDDK NIH HHS/ -- R01 DK078938/DK/NIDDK NIH HHS/ -- R01 GM099535/GM/NIGMS NIH HHS/ -- R21 DK083633/DK/NIDDK NIH HHS/ -- England -- Nature. 2013 Sep 19;501(7467):426-9. doi: 10.1038/nature12447. Epub 2013 Aug 18.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23955152" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bacterial Proteins/genetics/metabolism ; Bacteroides/*classification/genetics/growth & development/*physiology ; Bacteroides fragilis/genetics/growth & development/metabolism ; Colon/microbiology ; Conserved Sequence/genetics ; Evolution, Molecular ; Female ; Gastrointestinal Tract/*microbiology ; Gene Deletion ; Genes, Bacterial/genetics ; Germ-Free Life ; Intestinal Mucosa/microbiology ; Male ; Metagenome/*physiology ; Mice ; Polysaccharides/metabolism ; Species Specificity ; Symbiosis/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2012-10-05
    Description: Grain boundaries in graphene are formed by the joining of islands during the initial growth stage, and these boundaries govern transport properties and related device performance. Although information on the atomic rearrangement at graphene grain boundaries can be obtained using transmission electron microscopy and scanning tunnelling microscopy, large-scale information regarding the distribution of graphene grain boundaries is not easily accessible. Here we use optical microscopy to observe the grain boundaries of large-area graphene (grown on copper foil) directly, without transfer of the graphene. This imaging technique was realized by selectively oxidizing the underlying copper foil through graphene grain boundaries functionalized with O and OH radicals generated by ultraviolet irradiation under moisture-rich ambient conditions: selective diffusion of oxygen radicals through OH-functionalized defect sites was demonstrated by density functional calculations. The sheet resistance of large-area graphene decreased as the graphene grain sizes increased, but no strong correlation with the grain size of the copper was revealed, in contrast to a previous report. Furthermore, the influence of graphene grain boundaries on crack propagation (initialized by bending) and termination was clearly visualized using our technique. Our approach can be used as a simple protocol for evaluating the grain boundaries of other two-dimensional layered structures, such as boron nitride and exfoliated clays.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Duong, Dinh Loc -- Han, Gang Hee -- Lee, Seung Mi -- Gunes, Fethullah -- Kim, Eun Sung -- Kim, Sung Tae -- Kim, Heetae -- Ta, Quang Huy -- So, Kang Pyo -- Yoon, Seok Jun -- Chae, Seung Jin -- Jo, Young Woo -- Park, Min Ho -- Chae, Sang Hoon -- Lim, Seong Chu -- Choi, Jae Young -- Lee, Young Hee -- England -- Nature. 2012 Oct 11;490(7419):235-9. doi: 10.1038/nature11562. Epub 2012 Oct 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Sungkyunkwan Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23034653" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2014-10-11
    Description: Spatial and temporal dissection of the genomic changes occurring during the evolution of human non-small cell lung cancer (NSCLC) may help elucidate the basis for its dismal prognosis. We sequenced 25 spatially distinct regions from seven operable NSCLCs and found evidence of branched evolution, with driver mutations arising before and after subclonal diversification. There was pronounced intratumor heterogeneity in copy number alterations, translocations, and mutations associated with APOBEC cytidine deaminase activity. Despite maintained carcinogen exposure, tumors from smokers showed a relative decrease in smoking-related mutations over time, accompanied by an increase in APOBEC-associated mutations. In tumors from former smokers, genome-doubling occurred within a smoking-signature context before subclonal diversification, which suggested that a long period of tumor latency had preceded clinical detection. The regionally separated driver mutations, coupled with the relentless and heterogeneous nature of the genome instability processes, are likely to confound treatment success in NSCLC.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4636050/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4636050/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉de Bruin, Elza C -- McGranahan, Nicholas -- Mitter, Richard -- Salm, Max -- Wedge, David C -- Yates, Lucy -- Jamal-Hanjani, Mariam -- Shafi, Seema -- Murugaesu, Nirupa -- Rowan, Andrew J -- Gronroos, Eva -- Muhammad, Madiha A -- Horswell, Stuart -- Gerlinger, Marco -- Varela, Ignacio -- Jones, David -- Marshall, John -- Voet, Thierry -- Van Loo, Peter -- Rassl, Doris M -- Rintoul, Robert C -- Janes, Sam M -- Lee, Siow-Ming -- Forster, Martin -- Ahmad, Tanya -- Lawrence, David -- Falzon, Mary -- Capitanio, Arrigo -- Harkins, Timothy T -- Lee, Clarence C -- Tom, Warren -- Teefe, Enock -- Chen, Shann-Ching -- Begum, Sharmin -- Rabinowitz, Adam -- Phillimore, Benjamin -- Spencer-Dene, Bradley -- Stamp, Gordon -- Szallasi, Zoltan -- Matthews, Nik -- Stewart, Aengus -- Campbell, Peter -- Swanton, Charles -- 088340/Wellcome Trust/United Kingdom -- 091730/Wellcome Trust/United Kingdom -- 105104/Wellcome Trust/United Kingdom -- A11590/Cancer Research UK/United Kingdom -- A17786/Cancer Research UK/United Kingdom -- A19310/Cancer Research UK/United Kingdom -- A4688/Cancer Research UK/United Kingdom -- Cancer Research UK/United Kingdom -- Medical Research Council/United Kingdom -- New York, N.Y. -- Science. 2014 Oct 10;346(6206):251-6. doi: 10.1126/science.1253462.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London WC1E 6BT, UK. ; Cancer Research UK London Research Institute, London WC2A 3LY, UK. Centre for Mathematics and Physics in the Life Science and Experimental Biology (CoMPLEX), University College London, London WC1E 6BT, UK. ; Cancer Research UK London Research Institute, London WC2A 3LY, UK. ; Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK. ; Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK. University of Cambridge, Cambridge CB2 1TN, UK. ; Instituto de Biomedicina y Biotecnologia de Cantabria (CSIC-UC-Sodercan), Departamento de Biologia Molecular, Universidad de Cantabria, Santander, Spain. ; Wellcome Trust Sanger Institute, Hinxton, CB10 1SA, UK. Department of Human Genetics, University of Leuven, 3000 Leuven, Belgium. ; Papworth Hospital NHS Foundation Trust, Cambridge CB23 3RE, UK. ; Lungs for Living Research Centre, University College London, London WC1E 6BT, UK. ; Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London WC1E 6BT, UK. University College London Hospitals, London NW1 2BU, UK. ; University College London Hospitals, London NW1 2BU, UK. ; Thermo Fisher Scientific, Carlsbad, CA 92008, USA. ; Technical University of Denmark, 2800 Kongens Lyngby, Denmark. Children's Hospital Informatics Program, Harvard Medical School, Boston, MA 02115, USA. ; Cancer Research UK Lung Cancer Centre of Excellence, University College London Cancer Institute, London WC1E 6BT, UK. Cancer Research UK London Research Institute, London WC2A 3LY, UK. charles.swanton@cancer.org.uk.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25301630" target="_blank"〉PubMed〈/a〉
    Keywords: Carcinogens/toxicity ; Carcinoma, Non-Small-Cell Lung/chemically induced/*diagnosis/*genetics ; Cytidine Deaminase/genetics ; Evolution, Molecular ; Gene Dosage ; *Genetic Heterogeneity ; *Genomic Instability ; Humans ; Lung Neoplasms/chemically induced/*diagnosis/*genetics ; Mutation ; Neoplasm Recurrence, Local/genetics ; Prognosis ; Smoking/adverse effects ; Translocation, Genetic ; Tumor Cells, Cultured
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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