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  • American Society for Microbiology  (7)
  • 1990-1994  (7)
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  • American Society for Microbiology  (7)
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  • 1990-1994  (7)
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Subjects(RVK)
  • 1
    Online Resource
    Online Resource
    American Society for Microbiology ; 1991
    In:  Applied and Environmental Microbiology Vol. 57, No. 2 ( 1991-02), p. 440-444
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 57, No. 2 ( 1991-02), p. 440-444
    Abstract: A heterologous phosphotriesterase (parathion hydrolase), previously cloned from a Flavobacterium species into Streptomyces lividans, was secreted at high levels and purified to homogeneity. N-terminal analysis revealed that it had been processed in the same manner as the native membrane-bound Flavobacterium hydrolase. The enzyme consisted of a single polypeptide with an apparent molecular weight of 35,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Substrate specificity studies showed Kms of 68 microM for parathion, 46 microM for O-ethyl O-p-nitrophenyl phenylphosphonothioate, 599 microM for methyl parathion, and 357 microM for p-nitrophenyl ethyl(phenyl)phosphinate. Temperature and pH optima were 45 degrees C and 9.0, respectively. The purified enzyme was inhibited by 1 mM dithiothreitol and 1 mM CuSO4. After chelation and inactivation by o-phenanthroline, however, activity could be partially restored by 1 mM CuCl or 1 mM CuSO4. The results showed that the purified recombinant parathion hydrolase has the same characteristics as the native Flavobacterium hydrolase. This system provides a source of milligram quantities of parathion hydrolase for future structural and mechanism studies and has the potential to be used in toxic waste treatment strategies.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1991
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    American Society for Microbiology ; 1991
    In:  Applied and Environmental Microbiology Vol. 57, No. 2 ( 1991-02), p. 610-611
    In: Applied and Environmental Microbiology, American Society for Microbiology, Vol. 57, No. 2 ( 1991-02), p. 610-611
    Abstract: Pure recombinant Flavobacterium parathion hydrolase (an organophosphorus acid anhydrase) from Streptomyces lividans was found to hydrolyze the toxic nerve agent soman at only 0.1% of the rate observed with parathion as substrate. Studies with wild-type and recombinant strains of S. lividans support the lack of significant soman breakdown by the hydrolase and also indicate the presence in S. lividans of other significant hydrolytic enzymatic activity towards soman.
    Type of Medium: Online Resource
    ISSN: 0099-2240 , 1098-5336
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1991
    detail.hit.zdb_id: 223011-2
    detail.hit.zdb_id: 1478346-0
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    American Society for Microbiology ; 1994
    In:  Journal of Bacteriology Vol. 176, No. 4 ( 1994-02), p. 1172-1179
    In: Journal of Bacteriology, American Society for Microbiology, Vol. 176, No. 4 ( 1994-02), p. 1172-1179
    Abstract: Expression of the division initiation gene, divIB, of Bacillus subtilis vegetative growth was examined. lacZ fusion studies and transcription start point mapping have established that a sigma A promoter proximal to divIB is utilized in vivo. The -10 region of this promoter, which is located 93 bp upstream of the start codon, has been defined precisely by site-directed mutagenesis that destroys the promoter. Examination of transcripts by Northern (RNA) blotting has shown that there are at least two transcripts for divIB. The established proximal promoter was found to give rise to a very minor transcript which could not be convincingly demonstrated in wild-type cells but which became apparent upon insertion of a plasmid into the chromosome just upstream of this promoter. The major transcript for divIB originated from a site several kb upstream of the gene and is probably the same as the long polycistronic message also traversing the murD-spoVE-murG genes that was identified previously by others (A.D. Henriques, H. de Lencastre, and P.J. Piggot, Biochimie 74:735-748, 1992). Transcription from the proximal promoter alone, in an upstream-deletion mutant strain, provided sufficient DivIB for normal growth and division as well as sporulation.
    Type of Medium: Online Resource
    ISSN: 0021-9193 , 1098-5530
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1994
    detail.hit.zdb_id: 2968-3
    detail.hit.zdb_id: 1481988-0
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    American Society for Microbiology ; 1990
    In:  Journal of Clinical Microbiology Vol. 28, No. 12 ( 1990-12), p. 2608-2611
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 28, No. 12 ( 1990-12), p. 2608-2611
    Abstract: Cell-to-cell fusion plays an important role in the pathogenesis of human immunodeficiency virus type 1 (HIV-1) infections. An assay to measure the antifusion activity of serum has been developed by using the fusion event that occurs between H9 cells chronically infected with HIV-1 (H9IIIB) and fusion-susceptible MT-2 cells. The endpoint is determined by measuring neutral red uptake in cells after syncytium formation is allowed to occur in the presence of various serum dilutions. The assessment of antifusion activity in serum by neutral red uptake has been shown to correlate with syncytium reduction as determined by direct counting. The optimal number and ratio of cells in the suspension for efficiency and speed of the assay have been determined. With this assay it was shown that 50% of 36 serum specimens capable of neutralizing cell-free virions failed to inhibit syncytium formation. The assay can thus measure a distinct activity in HIV-1-immune human sera which is a subset of neutralization activity. Because of the potential role of this activity in the rate of disease progression and protective immune responses, the antifusion assay will be an important tool for the investigation of disease pathogenesis and for acquired immunodeficiency syndrome vaccine development. The assay can also be applied to the investigation of the pathogenesis of the fusion event at the cellular level. The ability to use absorbance measurements rather than syncytium counts as the endpoint facilitates direct computer-assisted data analysis, which expedites the performance of the assay.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1990
    detail.hit.zdb_id: 1498353-9
    detail.hit.zdb_id: 390499-4
    SSG: 12
    Location Call Number Limitation Availability
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  • 5
    Online Resource
    Online Resource
    American Society for Microbiology ; 1991
    In:  Journal of Virology Vol. 65, No. 9 ( 1991-09), p. 4936-4942
    In: Journal of Virology, American Society for Microbiology, Vol. 65, No. 9 ( 1991-09), p. 4936-4942
    Abstract: BALB/c mice were depleted of B cells by anti-mu treatment to investigate the pathogenesis of respiratory syncytial virus (RSV) infection in the absence of antibody. Termination of RSV replication after primary infection occurred with the same kinetics in anti-mu-treated mice as in phosphate-buffered saline (PBS)-treated controls. Yet, when rechallenged, anti-mu-treated mice were more permissive to RSV replication than PBS-treated controls. Anti-mu-treated mice also experienced greater illness than PBS-treated controls during both primary infection and rechallenge. Passive transfer of RSV-specific immune serum to anti-mu-treated mice before rechallenge reconstituted complete protection from RSV replication and diminished illness. Thus, RSV-specific antibody is not required to terminate RSV replication in primary infection, but without antibody, only partial immunity against rechallenge is induced. While it is unknown whether the mechanism is a direct effect on RSV titer or modulation of the illness-causing cellular immune response, the presence of RSV-specific antibody reduces illness in both primary RSV infection and rechallenge of mice.
    Type of Medium: Online Resource
    ISSN: 0022-538X , 1098-5514
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1991
    detail.hit.zdb_id: 1495529-5
    detail.hit.zdb_id: 80174-4
    Location Call Number Limitation Availability
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  • 6
    Online Resource
    Online Resource
    American Society for Microbiology ; 1992
    In:  Infection and Immunity Vol. 60, No. 9 ( 1992-09), p. 3780-3789
    In: Infection and Immunity, American Society for Microbiology, Vol. 60, No. 9 ( 1992-09), p. 3780-3789
    Abstract: To address the question of whether Salmonella-infected nonphagocytic cells could serve as target cells for recognition by antigen-specific, major histocompatibility complex class I-restricted cytotoxic T lymphocytes (CTL), four recombinant Salmonella typhimurium constructs that expressed full-length, or fragments of, influenza A virus nucleoprotein (NP) were made. The bacteria were shown to infect Chinese hamster ovary (CHO) cells. Appropriate major histocompatibility complex restriction molecules, HLA-B27 and H-2 Db, were transfected into CHO cells, which were then infected with recombinant S. typhimurium and used as targets for NP-specific CTL. The cells in which NP was expressed by intracellularly replicating bacteria were not lysed by NP-specific CTL, although they were killed when appropriate influenza A virus or peptides were used. Thus, S.typhimurium bacteria within nonphagocytic cells were resistant to CTL recognition. In contrast to these results, mice infected with recombinant S.typhimurium that expressed fragments of NP in the periplasm were primed for NP-specific CTL responses. The results indicate that CTL responses specific to Salmonella antigens can be generated, but the bacteria may be safe from the CTL attack once they have entered the nonphagocytic cells.
    Type of Medium: Online Resource
    ISSN: 0019-9567 , 1098-5522
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1992
    detail.hit.zdb_id: 1483247-1
    detail.hit.zdb_id: 218698-6
    Location Call Number Limitation Availability
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  • 7
    Online Resource
    Online Resource
    American Society for Microbiology ; 1992
    In:  Journal of Clinical Microbiology Vol. 30, No. 7 ( 1992-07), p. 1863-1866
    In: Journal of Clinical Microbiology, American Society for Microbiology, Vol. 30, No. 7 ( 1992-07), p. 1863-1866
    Abstract: The prevalence and global distribution of two circumsporozoite (CS) genotypes of Plasmodium vivax (VK210 and VK247) were determined by genetic analysis of isolates from 234 malaria-infected patients. Whole blood specimens were collected on filter paper from patients infected with malaria in Thailand, Mexico, Papua New Guinea, Peru, Afghanistan (Pakistan), India, and western Africa and from 50 asymptomatic smear-negative controls. Following extraction of DNA from the filter paper samples, the CS gene was amplified by the polymerase chain reaction and genotyped by using oligoprobes specific for the VK210 and VK247 repeat epitopes. The sensitivity of genotyping from a single blood dot was 95.2%. The VK247 CS genotype was identified in the blood of patients from all seven study areas and was the predominant form present in samples from Thailand (83%) and Papua New Guinea (90%). In contrast, VK247 DNA was present in only 9% of isolates from Mexico. Individuals infected with both genotypes simultaneously were identified in all study areas except Mexico and were particularly common in Thailand (58%) and Papua New Guinea (60%). These findings indicate that the VK247 genotype of P. vivax is widely distributed but that its prevalence varies geographically. In addition, we conclude that use of samples of whole blood on filter paper is a practical and sensitive method for determining the genotypes of large numbers of malaria isolates collected in field settings.
    Type of Medium: Online Resource
    ISSN: 0095-1137 , 1098-660X
    RVK:
    Language: English
    Publisher: American Society for Microbiology
    Publication Date: 1992
    detail.hit.zdb_id: 1498353-9
    detail.hit.zdb_id: 390499-4
    SSG: 12
    Location Call Number Limitation Availability
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