RESUMEN
A determinant for a protective antigen (pag) of Bacillus anthracis STI has been cloned. Its expression in Escherichia coli, Bacillus subtilis and Bacillus anthracis cells has been studied. The hybrid plasmids were obtained carrying the different fragments of the gene. The plasmids pPA2 and pPA3 having the 3'-end fragment of pag deleted (the size of 1 kb) still code for a part of protective antigen preserving the immunological and protective properties.
Asunto(s)
Antígenos Bacterianos/genética , Bacillus anthracis/inmunología , Bacillus subtilis/genética , Escherichia coli , Carbunco/inmunología , Bacillus anthracis/genética , Clonación Molecular , PlásmidosRESUMEN
Some regularities of [3H]triamcinolone acetonide (TA)binding to glucocorticoid-sensitive Morris hepatoma cell nuclei were studied. It was shown that part of the hormone incorporated into the nuclei form highly stable complexes with nuclear structures that are not destroyed during nuclei lysis with 0.25% SDS. Such complex formation is not practically suppressed by a 500-fold excess of non-labeled TA. As the time of incubation of Morris hepatoma cells with the hormone rises from 10 min to 24 hours, the specific binding of TA to the nuclei decreases, while the specific radioactivity of the [3H]TA-nuclei complexes resistant to 0.25% SDS increases. The stable complexes are eluted from Sepharose 6B together with the bulk of the nuclear proteins and do not contain DNA. Actinomycin D extrudes, to some extent, the [3H]TA from the complexes having specific binding sites that are localized in the nuclei and induces the accumulation of the steroid in the firmly bound nuclear complexes resistant to 0.25% SDS. The ability to suppress hormonal induction of tyrosine aminotransferase was detected only in the antibiotics with a high affinity for the GC-pairs of DNA. i.e., actinomycin D and mitramycin. It was assumed that high concentrations of TA specifically bound to the nuclei are necessary only at initial steps of hormonal induction. At later stages, gradual dissociation of the complexes takes place and the hormone is accumulation within the composition of the SDS-resistant firmly bound complexes.