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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 44 (1987), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A kanamycin-resistance plasmid, pUB110, was introduced into Bacillus anthracis by a newly devised method of transformation. The transformation frequency was ca. 1 × 103 cells/1 μg DNA.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In an enterohemorrhagic Escherichia coli (EHEC) O157:H7 outbreak caused by salted salmon roe that occurred in Japan, 1998, a food isolate (F2) was NaCl-resistant and a patient isolate (P5) was sensitive to NaCl. We show here that hydrogen peroxide, like NaCl, induced a significant loss of culturability in P5. The BacLight assay suggested that the EHEC O157:H7 entered a viable but nonculturable (VNC) state. We used the passage through mice in an attempt to model this transition in phenotype. Mouse-passaged isogenic variants of F2 became NaCl- and oxidation-sensitive, entered the nonculturable state in response to either of these stresses, and could be resuscitated by sodium pyruvate. Since the expression of RpoS in response to these stresses correlated with the isolates' culturabilities, we concluded that in vivo passage negatively modulated RpoS expression, and the subsequent stress exposure induced the VNC state in the EHEC O157:H7 isolates.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Vibrio cholerae O139, a causative agent of a large epidemic of cholera-like illness, has suddenly emerged and spread widely over several months. To investigate the characteristics unique to O139, traditional typing techniques for V. cholerae, such as biochemical characteristics, antibiotic susceptibility and detection of toxin production, were performed, with the result that 145 O139 strains, except for two O139 strains isolated from Argentina and Germany, were indistinguishable from O1 strains. Thus, in order to clarify the genetical relatedness among O139 strains, and between O139 and O1 strains, the RAPD (random amplified polymorphic DNA) DNA fingerprinting method was undertaken. Although the RAPD arrays in five O139 isolates from Vellore with one arbitrary primer were slightly different from the other O139 strains, the RAPD patterns of the 145 forty-five O139 strains except for two O139 strains from Argentina and Germany were quite similar to each other, but were different from those of O1 strains, indicating that those O139 epidemic strains are closely related to each other regardless of their place of isolation. Furthermore, the RAPD patterns of the O139 strains resembled those of E1 Tor strains rather than classical strain, and a small change in the RAPD pattern of O139 strains occurred during subculture for 200 generations. These results taken together suggested that O139 V. cholerae have emerged from a common origin associated with the E1 Tor strain.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The two major virulence factors of Bacillus anthracis are the tripartite toxin and the polyglutamate capsule, which are encoded by genes on the large plasmids, pX01 and pX02, respectively. The genes atxA, located on pX01, and acpA, located on pX02, encode positive frans-acting proteins that are involved in bicarbonate-mediated regulation of toxin and capsule production, respectively. A derivative strain cured of pX01 produced less capsular substance than the parent strain harbouring both pX01 and pX02, and electroporation of the strain cured of pX01 with a plasmid containing the cloned atxA gene resulted in an increased level of capsule production. An acpA-null mutant was complemented by not only acpA but also the atxA gene. The cap region, which is essential for encapsulation, contains three genes capB, capC, and cap A, arranged in that order. The atxA gene stimulated capsule synthesis from the cloned cap region. Transcriptional analysis of cap by RNA slot-blot hybridization and primer-extension analysis revealed that atxA activated expression of cap in trans at the transcriptional level. These results indicate that cross-talk occurs, in which the pX01-located gene, atxA, activates transcription of the cap region genes located on pX02. We identified two major apparent transcriptional start sites, designated P1 and P2, located at positions 731 bp and 625 bp, respectively, upstream of the translation-initiation codon of capB. Transcription initiated from P1 and P2 was activated by both atxA and acpA, and activation appeared to be stimulated by bicarbonate. Deletion analysis of the upstream region of the cap
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Brucella spp. are facultative intracellular pathogens that have the ability to survive and multiply in professional and non-professional phagocytes, and cause abortion in domestic animals and undulant fever in humans. The mechanism and factors of virulence are not fully understood. Nicotinamidase/pyrazinamidase mutant (pncA mutant) of Brucella abortus failed to replicate in HeLa cells, and showed a lower rate of intracellular replication than that of wild-type strain in macrophages. Addition of nicotinic acid, but not nicotinamide, into medium supported intracellular replication of pncA mutant in HeLa cells and macrophages. The pncA mutant was not co-localizing with either late endosomes or lysosomes. The B. abortus virB4 mutant was completely cleared from the spleens of mice after 4 weeks, while the pncA mutant showed a 1.5-log reduction of the number of bacteria isolated from spleens after 10 weeks. Although pncA mutant showed reduced virulence in mice and defective intracellular replication, its ability to confer protection against the virulent B. abortus strain 544 was fully retained. These results suggest that PncA does not contribute to intracellular trafficking of B. abortus, but contributes to utilization of nutrients required for intracellular growth. Our results indicate that detailed characterizations of the pncA mutant may help the improvement of currently available live vaccines.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A total of 321 uropathogenic Escherichia coli (UPEC) strains and 12 strains of E. coli isolated from stool samples of healthy individuals, which were previously shown to be positive in colony hybridization test using the usp (encoding for the uropathogenic-specific protein) DNA probe, were examined by PCR amplification to determine the size of the usp gene and the pathogenicity island (PI). Three types of size variation were observed for the usp gene and four types for the PI. Sequencing analysis of the PIs from seven representative strains (six UPEC and one from a normal healthy individual) revealed that the usp genes can be classified into two groups, each having different sequences in the 3′-terminal region. The peptides encoded by the three open reading frames (ORFs) downstream of usp had identical 23 amino acid residues in the C-terminal region. The subregion encoding these small ORFs has a mosaic structure constituted of six segments. The positions of these segments vary from strain to strain, and in some strains, two to four segments are deleted. This indicates that rearrangements occur frequently in this region and the mosaic arrangement apparently contributes to the size variation observed in the PCR examination of the usp genes and PIs.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: An outbreak caused by dried processed squids contaminated with Salmonella Oranienburg occurred in Japan in 1999. Isolates obtained from the causative food were resistant to NaCl osmotic stress, but isolates from the patients were sensitive to NaCl. Although strains from both sources were almost identical in their virulence in mice, a NaCl-resistant strain from food (Sa9911T) became NaCl-sensitive after passage in mice and a NaCl-sensitive strain from one patient (Sa99004) retained NaCl sensitivity after such passage. When dried squid was contaminated experimentally with both strains during processing, only Sa9911T was recovered directly from the final product. Nevertheless, the viability of the Sa99004 cells was over 90% found by fluorescent staining. We suggested that Sa99004 might become viable but non-culturable (VNC) by NaCl stress. This hypothesis was confirmed by resuscitation by efficient enrichment. We concluded that VNC S. Oranienburg would be potentially dangerous contaminants of NaCl-preserved foods and that measures to ensure their detection should be taken at the time of food inspection.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 186 (2000), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In a previous study, we isolated the spaA gene encoding the surface protective antigen A, SpaA, of Erysipelothrix rhusiopathiae, and found that the N-terminal region of SpaA was responsible for protective immunity against erysipelas and that the C-terminal region contained eight repeat units consisting of 20 amino acids comprising the binding domain on the Erysipelothrix cell surface. In this study, using recombinant SpaA proteins, we showed that the repeat region bound to the cell surfaces of various Gram-positive bacterial cells, SpaA was a membrane-associated protein, this association depended on the interaction with choline residues in teichoic acid, and SpaA bound to lipoteichoic acid (LTA) of Bacillus subtilis and Staphylococcus aureus. These results showed that LTA was required for the surface association of SpaA in E. rhusiopathiae and that such an association might be common among Gram-positive bacterial cells. We suggested that an LTA–SpaA complex might have an important role in the E. rhusiopathiae infection process.
    Type of Medium: Electronic Resource
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