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  • Blackwell Publishing Ltd  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 15 (1995), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A16 kb transcript of the ams region, which is essential for biosynthesis of amylovoran, the acidic exopolysaccharide of Erwinia amylovora, was detected by Northern hybridization analysis. The positive regulator RcsA enhanced transcription of the targe mRNA from the ams operon. The nucleotide sequence of this area revealed 12 open reading frames (ORFs), which are all transcribed in the same direction. Five ORFs corresponded to the previously mapped genes amsA to amsE, Sequence analysis of the insertion sites of several Tn5 mutations confirmed these data. Tn5 or site-directed mutagenesis of the ORFs 477, 377, 144, and 743 reveated an amytovoran-deficient phenotype, and the newly identified genes were named amsG, amsH, amsI, and amsF, respectivety. The predicted amino acid sequence of AmsG is highly homologous to gatactosyl-1 -phosphate undecaprenyl-phosphate transferases. AmsB and AmsD are similar to other glycosyl transferases, and AmsH may be related to BexD. A significant homology to mammalian phosphatases was observed for Amsl. AmsA shows characteristic motifs for membrane association and ATP binding. AmsF carries a secretory signal sequence in the N-terminus and could be involved in periplasmic processing of the repeating units. Complementation experiments located a promoter region required for gene expression as far as 500 bp upstream of amsG. It is preceded by a typical transcriptional termination sequence. A mutation upstream of the terminator did not affect amylovoran synthesis. Partial nucleotide sequences further upstream of the ams region showed homology to genes mapped at 45min on the Escherichia coli chromosome. A termination sequence was also found downstream of the ams operon at a distance of 16 kb from the promoter. Between amsF and this terminator, three additional ORFs were detected.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 211 (2002), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In order to find reasons for the absence of fire blight in most countries of the Southern hemisphere, bark samples from apple and pear trees in orchards of the Western Cape region in South Africa were extracted for bacteria which could be antagonistic to Erwinia amylovora. Screening was done in the late growth season and mainly Gram-positive bacteria were isolated. Approximately half of them produced growth inhibition zones on a lawn of E. amylovora. Most isolates were classified as Bacillus megaterium by microbiological assays and in API 50 test systems. They were visualized in the light microscope as non-motile large rods. These strains may not be responsible for the absence of fire blight in orchards, but they may indicate unfavourable climatic conditions for Gram-negative bacteria including E. amylovora. They may reduce the ability of E. amylovora to establish fire blight and could also be useful for application in biological disease control.
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 66 (1990), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Using oligonucleotide probes we have isolated a DNA fragment encoding an insecticidal toxin of the coleopteran specific Bacillus thuringiensis subsp. tenebrionis. The gene was altered by site directed mutagenesis at its 5′-end and adapted for general cloning and expression purposes with a linker including a start codon and new restriction sites. The constructs were inserted into several vector plasmids and expressed in Escherichia coli. Expression E. coli was strongly enhanced by the lac-promoter. A fusion protein with phage MS2-polymerase was produced together with a 76 kDa protein also found for normal expression of the toxin gene. Synthesis of the latter protein indicated a second ribosome binding site at the 5′-terminus of the toxin encoding sequence. Toxin-containing proteins were identified by Western blot analysis. The positive cell extracts from E. coli had been insecticidal activity on larvae of the Colorado potato breetle. The cloned gene is not homologous to a gene previously cloned by us whose gene products were also toxic to coleopteran larvae.
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 48 (1987), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A structural gene of a crystal protein toxic for coleoptera larvae was cloned from plasmid DNA of Bacillus thuringiensis subsp. tenebrionis (BTT). The DNA was partially digested with restriction enzyme BamHI and fragments were inserted into cosmid pHC79. In Western blot analysis extracts from infected Escherichia coli cells revealed expression of the BTT crystal protein in antibiotic-resistant cells. Cell lysates from a selected E. coli clone were toxic for larvae of the Colorado potato beetle (Leptinotarsa decemlineata). The electrophoretic mobility in SDS gels of crystal protein from E. coli cells was 68 kDa and 74 kDa as observed for BTT-toxin in B. thuringiensis extracts. The cosmids obtained were unstable during cellular propagation. The deletion product still carried the δ-endotoxin gene.
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