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  • 1
    Electronic Resource
    Electronic Resource
    Multicellular life cycle of magnetotactic prokaryotes (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 240 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Most multicellular organisms, prokaryotes as well as animals, plants, and algae have a unicellular stage in their life cycle. Here, we describe an uncultured prokaryotic magnetotactic multicellular organism that reproduces by binary fission. It is multicellular in all the stages of its life cycle, and during most of the life cycle the cells organize into a hollow sphere formed by a functionally coordinated and polarized single-cell layer that grows by increasing the cell size. Subsequently, all the cells divide synchronously; the organism becomes elliptical, and separates into two equal spheres with a torsional movement in the equatorial plane. Unicellular bacteria similar to the cells that compose these organisms have not been found. Molecular biology analysis showed that all the organisms studied belong to a single genetic population phylogenetically related to many-celled magnetotactic prokaryotes in the delta sub-group of the proteobacteria. This appears to be the first report of a multicellular prokaryotic organism that proliferates by dividing into two equal multicellular organisms each similar to the parent one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsle.2004.09.035
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Haem detoxification by an insect (1999)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 400 (1999), S. 517-518 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Haem is involved in many biological reactions, including oxygen transport, respiration and photosynthesis. In the free state, however, haem can generate reactive oxygen species that can damage biological molecules. It can also disrupt the phospholipid bilayer of cell membranes. In Plasmodium ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/22910
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Envelope ultrastructure of uncultured naturally occurring magnetotactic cocci (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 219 (2003), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Magnetotactic bacteria are microorganisms that respond to magnetic fields. We studied the surface ultrastructure of uncultured magnetotactic cocci collected from a marine environment by transmission electron microscopy using freeze-fracture and freeze-etching. All bacteria revealed a Gram-negative cell wall. Many bacteria possessed extensive capsular material and a S-layer formed by particles arranged with hexagonal symmetry. No indication of a metal precipitation on the surface of these microorganisms was observed. Numerous membrane vesicles were observed on the surface of the bacteria. Flagella were organized in bundles originated in a depression on the surface of the cells. Occasionally, a close association of the flagella with the magnetosomes that remained attached to the replica was observed. Capsules and S-layers are common structures in magnetotactic cocci from natural sediments and may be involved in inhibition of metal precipitation on the cell surface or indirectly influence magnetotaxis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0378-1097(02)01187-4
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  • 4
    Electronic Resource
    Electronic Resource
    Phosphorus-rich granules in uncultured magnetotactic bacteria (1999)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 172 (1999), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Amorphous intracellular minerals present in uncultured magnetotactic bacteria were studied with transmission electron microscopy, electron spectroscopic imaging and X-ray microanalysis. Amorphous minerals were present as intracellular granules that contained phosphorus, calcium and oxygen, and could also incorporate iron, aluminum and zinc. Granules showed evaporation typical of polyphosphate during exposure to high intensity electron beam. Morphologically different bacteria presented granules of variable size and number. This indicates that precipitation of amorphous minerals as phosphate granules is a characteristic feature of many uncultured magnetotactic bacteria. The structure and composition of granules and magnetosomes (known to contain the iron oxide magnetite) differ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1999.tb13444.x
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  • 5
    Electronic Resource
    Electronic Resource
    Phylogenetic affiliation and ultrastructure of uncultured magnetic bacteria with unusually large magnetosomes (1998)
    Springer
    Archives of microbiology 169 (1998), S. 136-147 
    Details
    ISSN: 1432-072X
    Keywords: Key words Magnetic bacteria ; Biomineralization ; Magnetite ; 16S rRNA ; In situ hybridization ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural enrichments of magnetic bacteria from the Itaipu lagoon near Rio de Janeiro were dominated by coccoid-to-ovoid morphotypes that produced unusually large magnetosomes. To determine the phylogenetic position of these unusual microorganisms, 16S rRNA genes were retrieved from bacteria magnetically separated from sediment of the Itaipu lagoon by in vitro amplification and cloning of PCR products into a plasmid vector. Partial sequencing of the obtained clones revealed two clusters of closely related sequences affiliated to a distinct lineage consisting exclusively of magnetic bacteria within the α-subclass of Proteobacteria. For a detailed phylogenetic analysis, several almost complete sequences of the 16S rRNA genes were determined. One representative clone of each cluster provided a PCR template for the in vitro transcription of group-specific polynucleotide probes complementary to a variable region of the 16S rRNA molecule. At least three different morphotypes of magnetic bacteria were reliably identified by post-embedding hybridization of ultra-thin sections. Electron microscopic analyses of hybridized cells enabled for the first time a detailed description of the morphological variety and ultrastructure of phylogenetically identified, uncultured magnetic bacteria. Two distinct coccoid bacteria were identified by the transcript probe complementary to the 16S rRNA sequence mabrj12, whereas the probe complementary to the sequence mabrj58 allowed the identification of an ovoid morphotype that displayed magnetosomes with the largest volumes observed to date.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050553
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    Paper (German National Licenses)
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