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  • 1
    Electronic Resource
    Electronic Resource
    Identification of 27-oxo-octacosanoic acid and heptacosane-1,27-dioic acid in Legionella pneumophila (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 97 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Two long-chain fatty acids, 27-oxo-octacosanoic acid (28:0(27-oxo)) and heptacosane-1,27-dioic acid (27:0-dioic) were identified for the first time in phenol-chloroform-petroleum ether extracts of Legionella pneumophila, indicating that they are constituents of lipopolysaccharide. The fatty acids were characterised by combined gas-liquid chromatography/mass spectrometry and proton nuclear magnetic resonance spectroscopy. Moreover, minor amounts of 29-oxo-triacontanoic (30:0(29-oxo)) acid and nonacosane-1,29-dioic acid (29:0-dioic) as well as 27-hydroxy-octacosanoic acid (28:0(27-OH)) were present in the phenol-chloroform-petroleum ether extract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05430.x
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  • 2
    Electronic Resource
    Electronic Resource
    The significance of the hydrophilic backbone and the hydrophobic fatty acid regions of lipid a for macrophage binding and cytokine induction (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS immunology and medical microbiology 8 (1994), S. 0 
    Details
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract Natural partial structures of lipopolysaccharide (LPS) as well as synthetic analogues and derivatives of lipid A were compared with respect to inhibit the binding of 125I-labelled Re-chemotype LPS to mouse macrophage-like J774.1 cells to induce cytokine-release in J774.1 cells. LPS, synthetic Escherichia coli-type lipid A (compound 506) and tetraacyl percursor Ia (compound 406) inhibited the binding of 125I-LPS to macrophage-like J774.1 cells and induced the release of tumor ncerosis factor α (TNFα) and interleukin 6 (IL-6). Deacylated R-chemotype LPS preparations were completely inactive in inhibiting binding and in inducing cytokine-release. Among tetraacyl compounds, the inhibition-capacity of LPS-binding was in decreasing order: PE-4 (α-phosphonooxyethyl analogue of 406)〉406⪢〉404(4′-monophosphoryl partial structure of 406)〉405 (1-monophosphoryl partial structure of 406). In the case of hexaccyl preparations, compounds 506, PE-1 (α-phosphonooxyethyl analogue of 506) and PE-2 (differing from PE-1 in having 14:0 at positions 2 and 3 of the reducing GlcN) inhibited LPS-binding and induced cytokine release equally well, whereas preparation PE-3 (differing from PE-2 in containing a β-phosphhonooxyethyl group) showed a substantially lower capacity in binding-inhibition and cytokine-induction. The conclusion is that chemical changes in the hydrophilic lipid A backbone reduce the capacity of lipid A to bind to cells, whereas the number of fatty acids determines the capacity of lipid A to activate cells. These results indicate that the bisphosphorylated hexosamine backbone of lipid A is essential for specific binding of LPS to macrophages and that the acylation pattern plays a critical role for LPS-promoted cell activation, i.e. cytokine induction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-695X.1994.tb00421.x
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  • 3
    Electronic Resource
    Electronic Resource
    Choline deficiency induced by Mycoplasma fermentans enhances apoptosis of rat astrocytes (2001)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 201 (2001), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A choline uptake system accumulating free choline in an energy-dependent process is described in Mycoplasma fermentans. The uptake system has a Km of 2.2×10−5 M and a Vmax of 0.15 nmol 10 min−1 mg−1 cell protein and the choline incorporated could be recovered in the soluble fraction as free choline, phosphorylcholine and CDP-choline. Choline accumulation by M. fermentans resulted in a marked choline depletion of the growth medium. The choline depletion of an astrocyte cell culture induced by M. fermentans was associated with the apoptotic death of the cells. Apoptosis was not obtained with heat-inactivated mycoplasmas and could be reversed by the addition of free choline to the growth medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2001.tb10750.x
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  • 4
    Electronic Resource
    Electronic Resource
    Corrigendum to “The phospocholine motif in membranes of Mycoplasma fermentans strains” (2001)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 201 (2001), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2001.tb10743.x
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  • 5
    Electronic Resource
    Electronic Resource
    The phosphocholine motif in membranes of Mycoplasma fermentans strains (2001)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 199 (2001), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Mycoplasma fermentans strains differ in the profile of choline-containing phosphoglycolipids (PGL) present in their cell membrane. MfGL-II [Zähringer et al. (1997) J. Biol. Chem. 272, 26262–26270] was found to be the major PGL in most strains tested. However, in the pulmonary isolates, M52 and M39 the major choline-containing PGLs were MfGL-I [Matsuda et al. (1994) J. Biol. Chem. 269, 33123–33129] and MfEL, a unique choline-containing ether lipid recently identified by us [Wagner et al. (2000) Eur. J. Biochem. 267, 6276–6286]. Both MfGL-I and MfEL were metabolically labeled by growing the cells with radioactive choline but only MfGL-I reacted with anti-phosphocholine antibodies. All tested strains fused with Molt-3 cells at almost the same rate and to about the same extent and in all the strains membrane proteins that reacted with anti-phosphocholine antibodies were detected, indicating that some membrane proteins are decorated with phosphocholine moieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2001.tb10664.x
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical and physicochemical characterization of the sialic acid-specific lectin from Cepaea hortensis (2002)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 214 (2002), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A sialic acid-specific lectin was isolated from the albumin glands of the garden snail Cepaea hortensis by affinity chromatography on fetuin-Sepharose following gel filtration on Superdex 200. The purified native lectin showed a molecular mass of about 95 kDa by gel filtration and 100 kDa by SDS electrophoresis. It was cleaved by boiling in buffer containing SDS in three serological identical bands corresponding to molecular masses of about 24, 20 and 16 kDa, respectively. From these three fragments, only the 24- and the 20-kDa bands were found to be glycosylated. Only the three sugars mannose, galactose and N-acetylglucosamine could be detected in a molar ratio of 3:8.6:2. The oligosaccharide moieties seem to be N- and partially O-glycosidic bound. Isoelectric focusing (IEF) of the purified lectin revealed a heterogeneous pattern with bands in the pH range of 4.3–5.0. Isolated bands of different isoelectric points showed in SDS electrophoresis the same three fragments with molecular masses of 24, 20 or 16 kDa. The heterogeneity of the lectin was revealed either by IEF or amino acid sequencing of internal tryptic peptides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2002.tb11325.x
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  • 7
    Electronic Resource
    Electronic Resource
    Antibody response to MfGL-II, a phosphocholine-containing major lipid of Mycoplasma fermentans membranes (1997)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 154 (1997), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The choline-containing phosphoglycolipid, MfGL-II, is the major polar lipid of Mycoplasma fermentans PG18. Anti-MfGL-II antisera raised in rabbits using the purified MfGL-II as an immunogen were employed in immunogold electron microscopic and immunofluorescence studies showing that MfGL-II is uniformly distributed and exposed on the cell surface of M. fermentans cells. The specificity of the antibodies was determined by immunostaining of lipid extracts separated by thin layer chromatography. The antibodies recognize lipids specific to M. fermentans but did not cross-react with lipid extracts of M. penetrans, M. capricolum, M. gallisepticum or Acholeplasma laidlawii. As phosphocholine almost completely abolished antibody interaction with MfGL-II in an ELISA assay it is suggested that the anti-MfGL-II repertoire is composed primarily of anti-phosphocholine antibodies. The anti-MfGL-II antisera inhibit the attachment of M. fermentans to Molt-3 lymphocytes suggesting that MfGL-II plays a major role in M. fermentans-host cell interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1997.tb12668.x
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  • 8
    Electronic Resource
    Electronic Resource
    The Neisseria gonorrhoeae lpxLII gene encodes for a late-functioning lauroyl acyl transferase, and a null mutation within the gene has a significant effect on the induction of acute inflammatory responses (2001)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 42 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: LPS is a fundamental constituent of the outer membrane of all Gram-negative bacteria, and the lipid A domain plays a central role in the induction of inflammatory responses. We identified genes of the Neisseria gonorrhoeae lipid A biosynthetic pathway by searching the complete gonococcal genome sequence with sequences of known enzymes from other species. The lpxLII gene was disrupted by an insertion–deletion in an attenuated aroA mutant of the gonococcal strain MS11. Lipopolysaccharide (LPS) and lipid A analysis demonstrated that the lpxLII mutant had synthesized an altered LPS molecule lacking a single lauric fatty acid residue in the GlcN II of the lipid A backbone. LPS of the lpxLII mutant had a markedly reduced ability to induce the proinflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-8 from human macrophages and IL-8 from polymorphonuclear cells. This study demonstrates that the lpxLII gene in gonococci encodes for a late-functioning lauroyl acyl transferase that adds a lauric acid at position 2′ in the lipid A backbone. The presence of lauric acid at such a position appears to be crucial for the induction of full inflammatory responses by N. gonorrhoeae LPS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02619.x
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  • 9
    Electronic Resource
    Electronic Resource
    Chromosomal insertion and excision of a 30 kb unstable genetic element is responsible for phase variation of lipopolysaccharide and other virulence determinants in Legionella pneumophila (2001)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 39 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We recently described the phase-variable expression of a virulence-associated lipopolysaccharide (LPS) epitope in Legionella pneumophila. In this study, the molecular mechanism for phase variation was investigated. We identified a 30 kb unstable genetic element as the molecular origin for LPS phase variation. Thirty putative genes were encoded on the 30 kb sequence, organized in two putative opposite transcription units. Some of the open reading frames (ORFs) shared homologies with bacteriophage genes, suggesting that the 30 kb element was of phage origin. In the virulent wild-type strain, the 30 kb element was located on the chromosome, whereas excision from the chromosome and replication as a high-copy plasmid resulted in the mutant phenotype, which is characterized by alteration of an LPS epitope and loss of virulence. Mapping and sequencing of the insertion site in the genome revealed that the chromosomal attachment site was located in an intergenic region flanked by genes of unknown function. As phage release could not be induced by mitomycin C, it is conceivable that the 30 kb element is a non-functional phage remnant. The protein encoded by ORF T on the 30 kb plasmid could be isolated by an outer membrane preparation, indicating that the genes encoded on the 30 kb element are expressed in the mutant phenotype. Therefore, it is conceivable that the phenotypic alterations seen in the mutant depend on high-copy replication of the 30 kb element and expression of the encoded genes. Excision of the 30 kb element from the chromosome was found to occur in a RecA-independent pathway, presumably by the involvement of RecE, RecT and RusA homologues that are encoded on the 30 kb element.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2001.02314.x
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  • 10
    Electronic Resource
    Electronic Resource
    Lipopolysaccharides of polymyxin B-resistant mutants of Escherichia coii are extensively substituted by 2-aminoethyl pyrophosphate and contain aminoarabinose in lipid A (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 16 (1995), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Lipopolysaccharides (LPS) of two polymyxin-resistant (pmr) mutants and the corresponding parent strain of Escherichia Coli were chemically analysed for composition and subjected to 31P-NMR (nuclear magnetic resonance) for assessment of phosphate substitution. Whereas the saccharide portions, fatty acids, and phosphate contents were similar in wild-type and pmr LPS, the latter contained two- to threefold higher amounts of 2-aminoethanol. The pmr LPS also contained 4-amino-4-deoxy-l-arabinopyranose (l-Arap4N), which is normally not a component of E. coli LPS. This aminopentose has been assigned to be linked to the 4′-phosphate of lipid A. Comparative 31P-NMR analysis of the de-O-acylated LPS of the wild-type and pmr strains revealed that phosphate groups of the pmr LPS were mainly (71-79%) diphosphate diesters, which accounted for only 20% in the wild-type LPS. Diphosphate monoesters were virtually nonexistent in the pmr LPS, whereas they accounted for 42% of all phosphates in wild-type LPS. In the lipid A of the pmr strains, the 4′-phosphate was to a significant degree (35%) substituted by l-Arap4N, whereas in the wild-type LPS the l-ArapN was absent. In the pmr lipid A1 2-aminoethanol was completely substituting the glycosidic pyrophosphate but not the glycosidic monophosphate, forming a diphosphate diester linkage at this position in 40% of lipid A molecules. In the wild-type LPS the glycosidic position of lipid A carried mostly unsubstituted monophosphate and pyrophosphate. Thus the polymyxin resistance was shown to be associated, along with the esterification of the lipid A 4′-monophosphate by aminoarabinose, with extensive esterification of diphosphates in LPS by 2-aminoethanol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1995.tb02299.x
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