Lurking leprosy. A new study suggests the leprosy bacterium can reprogram one type of nervous system cell to a stem cell-like state and use it to infiltrate other tissues in the body. Here, reprogrammed cells (green) fuse with and become skeletal muscles (red), spreading infection as they go. Cell nuclei are shown in blue. source : Leprosy reprograms the body, Science Now,17 January 2013. article : Masaki et al., Cell (2013)
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Lurking leprosy.

A new study suggests the leprosy bacterium can reprogram one type of nervous system cell to a stem cell-like state and use it to infiltrate other tissues in the body. Here, reprogrammed cells (green) fuse with and become skeletal muscles (red), spreading infection as they go. Cell nuclei are shown in blue.

source : Leprosy reprograms the body, Science Now,17 January 2013.

article : Masaki et al., Cell (2013)

Cultured human cell internalizing the infectious form of Chlamydia trachomatis The spore-like elementary bodies (EBs) of C. trachomatis have long been considered to be metabolically dormant, but Anders Omsland et al. report that EBs are capable of high levels of metabolic and biosynthetic activities that are independent of host cells. The findings may facilitate biochemical and physiological analyses of C. trachomatis. See the article by Omsland et al. on pages 19781–19785. Image courtesy of E. Fischer (National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD).
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Cultured human cell internalizing the infectious form of Chlamydia trachomatis

The spore-like elementary bodies (EBs) of C. trachomatis have long been considered to be metabolically dormant, but Anders Omsland et al. report that EBs are capable of high levels of metabolic and biosynthetic activities that are independent of host cells. The findings may facilitate biochemical and physiological analyses of C. trachomatis.

See the article by Omsland et al. on pages 19781–19785.

Image courtesy of E. Fischer (National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD).

Newly forming HIV virions embedded in the leading edge of dynamic filopodia. HIV infection of dendritic cells and other cells of myeloid lineage provides a potent reservoir from which HIV can later seed CD4 T cells. In dissecting the mechanisms of viral transfer from HIV-infected dendritic cells to CD4 T cells, a dynamic structure consisting of newly formed HIV virions being launched by probing filopodia was observed (see Aggarwal et al., doi:10.1371/journal.ppat.1002762). HIV incorporation into the tips of dendritic cell filopodia is observed in the image, with HIV particles in white and filopodial networks in red visualised by F-actin staining. Nuclear staining by DAPI is presented in blue. Image Credit: Anupriya Aggarwal and Stuart Turville, Kirby Institute, University of New South Wales source : PLoS Pathogens june 2012
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Newly forming HIV virions embedded in the leading edge of dynamic filopodia.

HIV infection of dendritic cells and other cells of myeloid lineage provides a potent reservoir from which HIV can later seed CD4 T cells. In dissecting the mechanisms of viral transfer from HIV-infected dendritic cells to CD4 T cells, a dynamic structure consisting of newly formed HIV virions being launched by probing filopodia was observed (see Aggarwal et al., doi:10.1371/journal.ppat.1002762). HIV incorporation into the tips of dendritic cell filopodia is observed in the image, with HIV particles in white and filopodial networks in red visualised by F-actin staining. Nuclear staining by DAPI is presented in blue.

Image Credit: Anupriya Aggarwal and Stuart Turville, Kirby Institute, University of New South Wales

source : PLoS Pathogens june 2012

Bactériophages Bacteriophages (bacteria-infecting viruses) target a single bacterial cell. The viruses anchor themselves to the bacteria’s cellular surface using proteinaceous tails before injecting their genomes into the bacterial host. Using the natural evolutionary specificity of bacteriophages could contribute to medical biology by targeting and curing increasingly resistant bacterial infections such as tuberculosis and streptococcus. Photo Credit: Lee D. Simon/Photo Researchers
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Bactériophages

Bacteriophages (bacteria-infecting viruses) target a single bacterial cell. The viruses anchor themselves to the bacteria’s cellular surface using proteinaceous tails before injecting their genomes into the bacterial host.

Using the natural evolutionary specificity of bacteriophages could contribute to medical biology by targeting and curing increasingly resistant bacterial infections such as tuberculosis and streptococcus.

Photo Credit: Lee D. Simon/Photo Researchers

(via biologylair)

Biofilm bactérien / Bacteria biofilmThis is Bacillus subtilis, a rod-shaped bacterium commonly found in soil. Distinct lineages of bacteria expressing different fluorescent proteins were initially mixed randomly on a petri dish. As bacteria grow, they organise themselves into reproducible patterns and shapes that can be predicted with mathematical models. The researchers took this image as part of a project designing artificial genetic circuits for pattern formation in bacterial colonies and plant tissues photographie de Fernan Federici, Tim Rudge, PJ Steiner and Jim Haseloff, Wellcome Images
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Biofilm bactérien / Bacteria biofilm

This is Bacillus subtilis, a rod-shaped bacterium commonly found in soil. Distinct lineages of bacteria expressing different fluorescent proteins were initially mixed randomly on a petri dish. As bacteria grow, they organise themselves into reproducible patterns and shapes that can be predicted with mathematical models. The researchers took this image as part of a project designing artificial genetic circuits for pattern formation in bacterial colonies and plant tissues

photographie de Fernan Federici, Tim Rudge, PJ Steiner and Jim Haseloff, Wellcome Images

Yersinia pseudotuberculosis à la surface de cellule HeLa a scanning electron microscope image shows wild-type Yersinia pseudotuberculosis (green) attached to the surface of cultured HeLa cells. photographie de Roland Rosqvist, Per Hörstedt, and Karen Akopyan (Umeå University, Umeå, Sweden); and Stefan Gunnarsson (Uppsala University, Uppsala). source : K. Akopyan et al., Translocation of surface-localized effectors in type III secretion, PNAS 1639–1644.
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Yersinia pseudotuberculosis à la surface de cellule HeLa

a scanning electron microscope image shows wild-type Yersinia pseudotuberculosis (green) attached to the surface of cultured HeLa cells.

photographie de Roland Rosqvist, Per Hörstedt, and Karen Akopyan (Umeå University, Umeå, Sweden); and Stefan Gunnarsson (Uppsala University, Uppsala).

source : K. Akopyan et al., Translocation of surface-localized effectors in type III secretion, PNAS 1639–1644.

Lymphocyte T excrétant le virus de la leucémie murine de Friend T cell shedding Friend murine leukemia viruses. Jason L. Kubinak et al. found that the Friend virus rapidly adapts to specific host major histocompatibility complex (MHC) genotypes, with viral fitness and virulence substantially higher in familiar versus unfamiliar MHC genotypes. The findings support the antagonistic coevolution model of MHC evolution, with a never-ending molecular arms race between pathogens and hosts promoting the maintenance of MHC diversity.  photograohie de Elizabeth R. Fischer and Kim J. Hasenkrug (National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT) source : Kubinak et al., Experimental viral evolution to specific host MHC genotypes reveals fitness and virulence trade-offs in alternative MHC types, PNAS 3422–3427.
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Lymphocyte T excrétant le virus de la leucémie murine de Friend

T cell shedding Friend murine leukemia viruses. Jason L. Kubinak et al. found that the Friend virus rapidly adapts to specific host major histocompatibility complex (MHC) genotypes, with viral fitness and virulence substantially higher in familiar versus unfamiliar MHC genotypes. The findings support the antagonistic coevolution model of MHC evolution, with a never-ending molecular arms race between pathogens and hosts promoting the maintenance of MHC diversity. 

photograohie de Elizabeth R. Fischer and Kim J. Hasenkrug (National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT)

source : Kubinak et al., Experimental viral evolution to specific host MHC genotypes reveals fitness and virulence trade-offs in alternative MHC types, PNAS 3422–3427.

Dictyostelium discoideum Dictyostelium discoideum or slime mold, is an amoeba; a single-celled organism, which spends most of its life on a diet of soil bacteria. Faced with famine, it has the unusual ability to form a ‘social’ structure to escape starvation. Amoebas clump together to form a ‘slug’ (bottom, left) that moves towards light. When the slug stops the cell-collective forms a fruiting body (far right), in which some cells die causing their companions to distribute widely (sporulation), in search of a better place to live. Dictyostelium is also a useful model organism. Many aspects of cellular biology in scenarios of health, disease and development depend on the ability of individual cells to communicate with their neighbours like these amoebas do. Many slime mold genes have human counterparts, so this amoeba can be used to investigate genes and test drugs of potential benefit to human health. source : BoD 03/04/12 Copyright M.J. Grimson & R.L. BlantonBiological Sciences Electron Microscopy Laboratory, Texas Tech University.
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Dictyostelium discoideum

Dictyostelium discoideum or slime mold, is an amoeba; a single-celled organism, which spends most of its life on a diet of soil bacteria. Faced with famine, it has the unusual ability to form a ‘social’ structure to escape starvation. Amoebas clump together to form a ‘slug’ (bottom, left) that moves towards light. When the slug stops the cell-collective forms a fruiting body (far right), in which some cells die causing their companions to distribute widely (sporulation), in search of a better place to live. Dictyostelium is also a useful model organism. Many aspects of cellular biology in scenarios of health, disease and development depend on the ability of individual cells to communicate with their neighbours like these amoebas do. Many slime mold genes have human counterparts, so this amoeba can be used to investigate genes and test drugs of potential benefit to human health.

source : BoD 03/04/12

Copyright M.J. Grimson & R.L. Blanton
Biological Sciences Electron Microscopy Laboratory, Texas Tech University.
Comparaison du génome de huit souches d’E. coli entéroagrégative O104:H4 the eight circular bands represent the tracks for the different enteroaggregative E. coli (EAEC) O104:H4 isolates sequenced in this study (from inner to outer tracks: 55989, C227-11, C734-09, C35-10, C682-09, C760-09, C754-09, and C777-09). These different bands represent coverage plots mapped against the reference genome 55989, with blue or green indicating a high degree of coverage, yellow moderate coverage, and orange or red little or no coverage. source : David A. Rasko and all, Origins of the E. coli Strain Causing an Outbreak of Hemolytic–Uremic Syndrome in Germany, N Engl J Med 2011; 365:709-717, August 25, 2011
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Comparaison du génome de huit souches d’E. coli entéroagrégative O104:H4

the eight circular bands represent the tracks for the different enteroaggregative E. coli (EAEC) O104:H4 isolates sequenced in this study (from inner to outer tracks: 55989, C227-11, C734-09, C35-10, C682-09, C760-09, C754-09, and C777-09). These different bands represent coverage plots mapped against the reference genome 55989, with blue or green indicating a high degree of coverage, yellow moderate coverage, and orange or red little or no coverage.

source : David A. Rasko and all, Origins of the E. coli Strain Causing an Outbreak of Hemolytic–Uremic Syndrome in Germany, N Engl J Med 2011; 365:709-717, August 25, 2011