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Biological Properties and Cell Tropism of Chp2, a Bacteriophage of the Obligate Intracellular Bacterium Chlamydophila abortus. J. S. Everson, 2002.A number of bacteriophages belonging to the Microviridae have been described infecting chlamydiae . Phylogenetic studies divide the Chlamydiaceae into two distinct genera, Chlamydia and Chlamydophila, containing three and six different species, respectively . In this work we investigated the biological properties and host range of the recently described bacteriophage Chp2 that was originally discovered in Chlamydophila abortus . The obligate intracellular development cycle of chlamydiae has precluded the development of quantitative approaches to assay bacteriophage infectivity . Thus, we prepared hybridomas secreting monoclonal antibodies (monoclonal antibodies 40 and 55) that were specific for Chp2 . We demonstrated that Chp2 binds both C . abortus elementary bodies and reticulate bodies in an enzyme-linked immunosorbent assay . Monoclonal antibodies 40 and 55 also detected bacteriophage Chp2 antigens in chlamydia-infected eukaryotic cells . We used these monoclonal antibodies to monitor the ability of Chp2 to infect all nine species of chlamydiae . Chp2 does not infect members of the genus Chlamydia (C . trachomatis, C . suis, or C . muridarum) . Chp2 can infect C . abortus, C . felis, and C . pecorum but is unable to infect other members of this genus, including C . caviae and C . pneumoniae, despite the fact that these chlamydial species support the replication of very closely related bacteriophages . Bacillus subtilis 168 Contains Two Differentially Regulated Genes Encoding L-Asparaginase. Susan H. Fisher, 2002.Expression of the two Bacillus subtilis genes encoding L-asparaginase is controlled by independent regulatory factors . The ansZ gene (formerly yccC) was shown by mutational analysis to encode a functional L-asparaginase, the expression of which is activated during nitrogen-limited growth by the TnrA transcription factor . Gel mobility shift and DNase I footprinting experiments indicate that TnrA regulates ansZ expression by binding to a DNA site located upstream of the ansZ promoter . The expression of the ansA gene, which encodes the second L-asparaginase, was found to be induced by asparagine . The ansA repressor, AnsR, was shown to negatively regulate its own expression .
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