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Braunschweig, Germany

Lefevre C.T.,Aix - Marseille University | Trubitsyn D.,University of Nevada, Las Vegas | Abreu F.,Federal University of Rio de Janeiro | Kolinko S.,Ludwig Maximilians University of Munich | And 11 more authors.
Environmental Microbiology | Year: 2013

Magnetotactic bacteria (MTB) represent a group of diverse motile prokaryotes that biomineralize magnetosomes, the organelles responsible for magnetotaxis. Magnetosomes consist of intracellular, membrane-bounded, tens-of-nanometre-sized crystals of the magnetic minerals magnetite (Fe3O4) or greigite (Fe3S4) and are usually organized as a chain within the cell acting like a compass needle. Most information regarding the biomineralization processes involved in magnetosome formation comes from studies involving Alphaproteobacteria species which biomineralize cuboctahedral and elongated prismatic crystals of magnetite. Many magnetosome genes, the mam genes, identified in these organisms are conserved in all known MTB. Here we present a comparative genomic analysis of magnetotactic Deltaproteobacteria that synthesize bullet-shaped crystals of magnetite and/or greigite. We show that in addition to mam genes, there is a conserved set of genes, designated mad genes, specific to the magnetotactic Deltaproteobacteria, some also being present in CandidatusMagnetobacterium bavaricum of the Nitrospirae phylum, but absent in the magnetotactic Alphaproteobacteria. Our results suggest that the number of genes associated with magnetotaxis in magnetotactic Deltaproteobacteria is larger than previously thought. We also demonstrate that the minimum set of mam genes necessary for magnetosome formation in Magnetospirillum is also conserved in magnetite-producing, magnetotactic Deltaproteobacteria. Some putative novel functions of mad genes are discussed. © 2013 John Wiley & Sons Ltd and Society for Applied Microbiology. Source

Jogler C.,Leibniz Institute DSMZ
Molecular Microbiology | Year: 2014

Organelles are membrane-enclosed compartments that serve a dedicated physiological purpose. While eukaryotic organelles are common textbook knowledge, bacteria were long thought to lack such subcellular organization. However, Planctomycetes were proposed to comprise a compartmentalized cell plan, including membrane-enclosed organelles such as the paryphoplasm, the pirellulosome, a nucleus-like membrane system and the anammoxosome. The latter is the hallmark of anaerobic ammonium oxidizing (anammox) bacteria, which gain energy by coupling the oxidation of ammonium to the reduction of nitrite. Since calculations indicate that 50% of nitrogen gas in the earth atmosphere results from anammox activity, this process is key for the global nitrogen cycle. Despite strong evidence for a confined compartment housing this reaction, the concept of planctomycetal compartmentalization in general is currently under debate and the presence of organelles in these bacteria was questioned. However, Neumann etal. (2014) report the isolation of physiological functional anammoxosomes from 'CandidatusKuenenia stuttgartiensis'. Subsequent proteomic and microscopic analysis revealed a confined organelle, paralleling eukaryotic mitochondria. This advance is of major importance for the understanding of bacterial compartmentalization in general and of the Planctomycetes in particular. Furthermore, the work of Neumann etal. leads to a better understanding of the anammox process. © 2014 John Wiley & Sons Ltd. Source

O'Brien K.,Trinity College Dublin | Lowry M.C.,Trinity College Dublin | Corcoran C.,Trinity College Dublin | Martinez V.G.,Trinity College Dublin | And 6 more authors.
Oncotarget | Year: 2015

Exosomes (EVs) have relevance in cell-to-cell communication carrying protumorigenic factors that participate in oncogenesis and drug resistance and are proposed to have potential as self-delivery systems. Advancing on our studies of EVs in triple-negative breast cancer, here we more comprehensively analysed isogenic cell line variants and their EV populations, tissues cell line variants and their EV populations, as well as breast tumour and normal tissues. Profiling 384 miRNAs showed EV miRNA content to be highly representative of their cells of origin. miRNAs most substantially down-regulated in aggressive cells and their EVs originated from 14q32. Analysis of miR-134, the most substantially down-regulated miRNA, supported its clinical relevance in breast tumours compared to matched normal breast tissue. Functional studies indicated that miR-134 controls STAT5B which, in turn, controls Hsp90. miR-134 delivered by direct transfection into Hs578Ts(i)8 cells (in which it was greatly down-regulated) reduced STAT5B, Hsp90, and Bcl-2 levels, reduced cellular proliferation, and enhanced cisplatin-induced apoptosis. Delivery via miR-134-enriched EVs also reduced STAT5B and Hsp90, reduced cellular migration and invasion, and enhanced sensitivity to anti-Hsp90 drugs. While the differing effects achieved by transfection or EV delivery are likely to be, at least partly, due to specific amounts of miR-134 delivered by these routes, these EV-based studies identified miRNA-134 as a potential biomarker and therapeutic for breast cancer. Source

Montero-Calasanz M.C.,Leibniz Institute DSMZ | Montero-Calasanz M.C.,IFAPA Institute Investigacion y Formacion Agraria y Pesquera | Goker M.,Leibniz Institute DSMZ | Rohde M.,Helmholtz Center for Infection Research | And 7 more authors.
International Journal of Systematic and Evolutionary Microbiology | Year: 2013

A novel non-motile, Gram-staining-negative, yellow-pigmented bacterium, designated AG13T, isolated from a rain water pond at a plant nursery in Spain and characterized as a plant-growth-promoting bacterium, was investigated to determine its taxonomic status. The isolate grew best over a temperature range of 15-40 °C, at pH 5.0-8.0 and with 0-4 % (w/v) NaCl. Chemotaxonomic and molecular characteristics of the isolate matched those described for members of the genus Chryseobacterium. The DNA G+C content of the novel strain was 37.2 mol%. The strain had a polyamine pattern with sym-homospermidine as the major compound and produced flexirubin-type pigments. MK-6 was the dominant menaquinone and the major cellular fatty acids were iso-C15: 0, C17: 1ω9c and iso-C17: 0 3-OH. The main polar lipids were phosphatidylethanolamine, aminolipids and several unidentified lipids. The 16S rRNA gene showed 92.0-97.2 % sequence similarity with those of the members of the genus Chryseobacterium. Based on chemotaxonomic and phenotypic traits, and DNA-DNA hybridizations with the type strains of the most closely related species, the isolate is proposed to represent a novel species, Chryseobacterium hispalense, type strain AG13T (= DSM 25574T = CCUG 63019T). Emended descriptions of the species Chryseobacterium defluvii, Chryseobacterium indologenes, Chryseobacterium wanjuense and Chryseobacterium gregarium are also provided. © 2013 IUMS. Source

Meier-Kolthoff J.P.,Leibniz Institute DSMZ | Auch A.F.,University of Tubingen | Klenk H.-P.,Leibniz Institute DSMZ | Goker M.,Leibniz Institute DSMZ
Concurrency Computation Practice and Experience | Year: 2014

Genome Blast Distance Phylogeny (GBDP) infers distances and phylogenetic relationships between organisms from completely or partially sequenced genomes. It is well suited for parallelization as pairwise distances are calculated independently. As exemplar data for a high-performance cluster implementation that executes many pairwise genome comparisons in parallel, we here used sequences from the Genomic Encyclopedia of Bacteria and Archaea project. Phylogenies were inferred from genome-scale nucleotide and amino acid data with all variants of GBDP, including novel adaptations to amino acid sequences and approaches yielding trees with branch support. The dependency of phylogenetic accuracy, average branch support as well as performance indicators such as running time and disk space consumption on details of genome comparison, distance calculation, and phylogenetic inference was examined in detail. If combined with conservative measures for branch support, GBDP appears to infer reasonable phylogenetic relationships of microorganisms with a comparatively low computational cost. Due to the linear speed-up of the cluster, benchmarks reveal an overall computation time of less than 24 h required for the 7750 pairwise genome/proteome comparisons of the Genomic Encyclopedia of Bacteria and Archaea data set that is opposed to an estimated running time of about 30 days for the non-parallelized version. Copyright © 2013 John Wiley & Sons, Ltd. Source

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