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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 152 (1989), S. 572-577 
    ISSN: 1432-072X
    Keywords: Chlamydomonas reinhardtii ; Gametic differentiation ; Light requirement ; Light-pulse-studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gametes of Chlamydomonas reinhardtii synthesize numerous proteins not observed in vegetative cells and vice versa. Gametogenesis induced changes in gene expression were confirmed by SDS-PAGE of in vitro translation products using total RNA from gametes and vegetative cells. Vegetative cells and gametes thus represent two cell types with distinct patterns of gene expression. The generation of mature gametes from liquid cultures of asynchronously growing vegetative cells was dependent on light. This light requirement could not be substituted for by an organic source of energy and carbon, indicating that light serves as a signal in gametogenesis. The light signal was shown to become effective only after preincubation in nitrogen-free medium. This delayed competence for light indicates that the two external signals — nitrogen-starvation and light —may function in sequence. Execution of the light dependent step in gamete formation required cytoplasmic protein synthesis and RNA synthesis.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Molecular genetics and genomics 205 (1986), S. 146-152 
    ISSN: 1617-4623
    Keywords: Cellobiase ; Oligodeoxyribonucleotide ; Expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The β-glucosidase from ATCC 21400, anAgrobacterium species, was purified to homogeneity. The protein was cleaved with cyanogen bromide and the peptides were purified by reversed phase FPLC. The partial amino acid sequence for one peptide was determined by automated Edman degradation. The sequence was used to synthesize a mixture of oligodeoxyribonucleotides which was used as a hybridization probe to identify a recombinant DNA clone carrying the gene for β-glucosidase. A single clone was isolated which expressed an enzymatic activity that hydrolyzed several β-glucosides. The enzymatic activity produced by this clone could be adsorbed by rabbit antiserum raised against theAgrobacterium enzyme. The direction of transcription of the β-glucosidase gene was determined by verifying the DNA sequence 3′ to the oligodeoxyribonucleotide probe binding site. After subcloning the gene a high level of expression was obtained in the plasmid vector pUC18 using the lacZ gene promoter.
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature structural & molecular biology 11 (2004), S. 163-170 
    ISSN: 1545-9985
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Sialic acid terminates oligosaccharide chains on mammalian and microbial cell surfaces, playing critical roles in recognition and adherence. The enzymes that transfer the sialic acid moiety from cytidine-5′-monophospho-N-acetyl-neuraminic acid (CMP-NeuAc) to the terminal positions of these ...
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 37 (2000), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Ganglioside mimicry by Campylobacter jejuni lipo-oligosaccharide (LOS) is thought to be a critical factor in the triggering of the Guillain–Barré and Miller–Fisher syndrome neuropathies after C. jejuni infection. The combination of a completed genome sequence and a ganglioside GM1-like LOS structure makes C. jejuni NCTC 11168 a useful model strain for the identification and characterization of the genes involved in the biosynthesis of ganglioside-mimicking LOS. Genome analysis identified a putative LOS biosynthetic cluster and, from this, we describe a putative gene (ORF Cj1139c), which we have termed wlaN, with a significant level of similarity to a number of bacterial glycosyltransferases. Mutation of this gene in C. jejuni NCTC 11168 resulted in a LOS molecule of increased electrophoretic mobility, which also failed to bind cholera toxin. Comparison of LOS structural data from wild type and the mutant strain indicated lack of a terminal β-1,3-linked galactose residue in the latter. The wlaN gene product was demonstrated unambiguously as a β-1,3 galactosyltransferase responsible for converting GM2-like LOS structures to GM1-like by in vitro expression. We also show that the presence of an intragenic homopolymeric tract renders the expression of a functional wlaN gene product phase variable, resulting in distinct C. jejuni NCTC 11168 cell populations with alternate GM1 or GM2 ganglioside-mimicking LOS structures. The distribution of wlaN among a number of C. jejuni strains with known LOS structure was determined and, for C. jejuni NCTC 12500, similar wlaN gene phase variation was shown to occur, so that this strain has the potential to synthesize a GM1-like LOS structure as well as the ganglioside GM2-like LOS structure proposed in the literature.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd.
    Molecular microbiology 55 (2005), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We recently demonstrated that Campylobacter jejuni produces a capsular polysaccharide (CPS) that is the major antigenic component of the classical Penner serotyping system distinguishing Campylobacter into 〉60 groups. Although the wide variety of C. jejuni serotypes are suggestive of structural differences in CPS, the genetic mechanisms of such differences are unknown. In this study we sequenced biosynthetic cps regions, ranging in size from 15 to 34 kb, from selected C. jejuni strains of HS:1, HS:19, HS:23, HS:36, HS:23/36 and HS:41 serotypes. Comparison of the determined cps sequences of the HS:1, HS:19 and HS:41 strains with the sequenced strain, NCTC11168 (HS:2), provides evidence for multiple mechanisms of structural variation including exchange of capsular genes and entire clusters by horizontal transfer, gene duplication, deletion, fusion and contingency gene variation. In contrast, the HS:23, HS:36 and HS:23/36 cps sequences were highly conserved. We report the first detailed structural analysis of 81-176 (HS:23/36) and G1 (HS:1) and refine the previous structural interpretations of the HS:19, HS:23, HS:36 and HS:41 serostrains. For the first time, we demonstrate the commonality and function of a second heptose biosynthetic pathway for Campylobacter CPS independent of the pathway for lipooligosaccharide (LOS) biosynthesis and identify a novel heptosyltransferase utilized by this alternate pathway. Furthermore, we show the retention of two functional heptose isomerases in Campylobacter and the sharing of a phosphatase for both LOS and CPS heptose biosynthesis.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 39 (2001), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: We have identified a gene for the addition of N-acetylneuraminic acid (Neu5Ac) in an α-2,3-linkage to a lactosyl acceptor moiety of the lipopolysaccharide (LPS) of the human pathogen Haemophilus influenzae. The gene is one that was identified previously as a phase-variable gene known as lic3A. Extracts of H. influenzae, as well as recombinant Escherichia coli strains producing Lic3A, demonstrate sialyltransferase activity in assays using synthetic fluorescent acceptors with a terminal galactosyl, lactosyl or N-acetyl-lactosaminyl moiety. In the RM118 strain of H. influenzae, Lic3A activity is modulated by the action of another phase-variable glycosyltransferase, LgtC, which competes for the same lactosyl acceptor moiety. Structural analysis of LPS from a RM118:lgtC mutant and the non-typeable strain 486 using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy confirmed that the major sialylated species has a sialyl-α-(2–3)-lactosyl extension off the distal heptose. This sialylated glycoform was absent in strains containing a lic3A gene disruption. Low amounts of sialylated higher molecular mass glycoforms were present in RM118:lgtC lic3A, indicating the presence of a second sialyltransferase. Lic3A mutants of H. influenzae strains show reduced resistance to the killing effects of normal human serum. Lic3A, encoding an α-2,3-sialyltransferase activity, is the first reported phase-variable sialyltransferase gene.
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature structural biology 8 (2001), S. 166-175 
    ISSN: 1072-8368
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] Many bacterial pathogens express lipooligosaccharides that mimic human cell surface glycoconjugates, enabling them to attach to host receptors and to evade the immune response. In Neisseria meningitidis, the galactosyltransferase LgtC catalyzes a key step in the biosynthesis of lipooligosaccharide ...
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 18 (1992), S. 143-146 
    ISSN: 1573-5028
    Keywords: Chlamydomonas reinhardtii ; direct repeats ; GC-rich sequences ; molecular evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Glycoconjugate journal 16 (1999), S. 507-515 
    ISSN: 1573-4986
    Keywords: GM3 antigen ; sialyllactoside ; biantennary ; glycoconjugate ; antibody ; CTP, Cytidine 5′-triphosphate ; KLH, Keyhole Limpet Hemocyanin ; M2C2H, 4-(4-N-maleimidomethyl) cyclohexane-1-carboxyl hydrazide ; MPL, Monophosphoryl lipid A ; Sulfo-GMBS, N-(γ-maleimidobutyryloxy) sulfosuccinimide ester ; BSA, Bovine serum albumin ; HSA, Human serum albumin ; GBSPIa (GBSPIII), Type Ia (III) group B Streptococcus polysaccharide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A biantennary GM3-saccharide (sialyllactoside) derivative (4) was constructed using allylmalonic acid as a bivalent linker, both carboxylic acids of which were condensed with 3-aminopropyl lactoside (2) prior to enzymatic sialylation with a fusion enzyme. While ozonolysis of its allyl group generated a saccharide having a terminal aldehyde (6), we were unable to couple 6 directly to protein by reductive amination. However, extension of the spacer by means of introducing a maleimide group to 6 through its aldehyde group to give 7 enabled the latter to be successfully coupled to thiolated proteins. The average ratios of saccharide to protein were observed to be 35 in KLH conjugate (13) and 9–12 in HSA conjugates (14 and 15). The antisera obtained by immunizing mice with the biantennary sialyllactoside-KLH conjugate (13) together with MPL adjuvant were analyzed by ELISA. Using several structurally related saccharide-HSA conjugates as screening antigens, it was concluded that anti-sialyllactoside antibodies, both IgG and IgM, were effectively raised. This was further supported by competitive inhibition experiments using lactoside (1), sialyllactoside (8) and biantennary sialyllactoside (4) as inhibitors.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Glycoconjugate journal 16 (1999), S. 205-212 
    ISSN: 1573-4986
    Keywords: oligosaccharides ; glycosyltransferases ; glycobiology ; N-acetyllactosamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Scientific and commercial interest in oligosaccharides is increasing, but their availability is limited as production relies on chemical or chemo-enzymatic synthesis. In search for a more economical, alternative procedure, we have investigated the possibility of producing specific oligosaccharides in E. coli that express the appropriate glycosyltransferases. The Azorhizobium chitin pentaose synthase NodC (a β(1,4)GlcNAc-transferase), and the Neisseria β(1,4)galactosyltransferase LgtB, were co-expressed in E. coli. The major oligosaccharide isolated from the recombinant strain, was subjected to LC-MS, FAB-MS and NMR analysis, and identified as βGal(1,4)[βGlcNAc(1,4)]4GlcNAc. High cell density culture yielded more than 1.0 gr of the hexasaccharide per liter of culture. The compound was found to be an acceptor in vitro for βGal(1,4)GlcNAc α(1,3)galactosyltransferase, which suggests that the expression of additional glycosyltransferases in E. coli will allow the production of more complex oligosaccharides.
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