RESUMO
Transduction of Bacillus subtilis pUB110 plasmid by AR9 phage is described. Some aspects of this process are studied. Plasmid transduction depended on multiplicity of infection similar to cases of chromosomal markers transduction, though optimal multiplicity of infection was achieved using low number of phage particles. No cotransduction of plasmid and chromosomal markers was demonstrated. The transduction frequencies of plasmid and chromosomal markers increased after UV irradiation of phage suspensions within the range of definite doses.
Assuntos
Bacillus subtilis/genética , DNA Bacteriano/genética , Plasmídeos , Transdução Genética , Cromossomos Bacterianos/efeitos da radiação , Resistência Microbiana a Medicamentos/efeitos da radiação , Marcadores Genéticos/efeitos da radiação , Plasmídeos/efeitos da radiação , Transdução Genética/efeitos da radiação , Raios UltravioletaRESUMO
The ability of different Bacillus subtilis rec mutants for transformation and transduction by plasmid DNA and influence of these mutations on plasmid recombination was studied. The efficiency of plasmid transformation was found to be decreased in most cases. Plasmid transduction depended slightly on any rec mutation in recipient cells. When rec mutants carrying pUB110 plasmid were transformed with pBD12 DNA which is homologous to the resident plasmid, different values fo "marker rescue" were observed. Several strains demonstrate the effect similar to that in recombination-proficient strains, while others exhibit the decreased values or no effect at all. These results indicate that plasmid and chromosomal recombination have common recombinational steps, though there are also some differences in both types of recombination.
Assuntos
Bacillus subtilis/genética , Mutação , Plasmídeos , Transdução Genética , Transformação Bacteriana , DNA Bacteriano/genética , Marcadores Genéticos , Recombinação GenéticaRESUMO
The influence of ethidium bromide, actinomycin D and acridine orange treatment of Bacillus subtilis competent cells on plasmid transformation, recombination and transduction was studied. The drugs were administered at different times after DNA uptake. The yield of plasmid recombinants and transformants was inhibited in different ways during the first 30 minutes. Probably, it was the result of damaging the synaptic stage of recombination because of DNA conformational changes. The effect of drugs on plasmid transduction was significantly lesser.
Assuntos
Bacillus subtilis/efeitos dos fármacos , DNA Bacteriano/genética , Plasmídeos/efeitos dos fármacos , Recombinação Genética/efeitos dos fármacos , Transdução Genética/efeitos dos fármacos , Transformação Bacteriana/efeitos dos fármacos , Laranja de Acridina/farmacologia , Bacillus subtilis/genética , Dactinomicina/farmacologia , Etídio/farmacologia , Substâncias Intercalantes/farmacologia , Conformação MolecularRESUMO
Plasmid pUB110 DNA is restricted and modified during transformation of Bacillus subtilis cells possessing the BsuR system of restriction-modification. Restriction has comparatively little influence on the frequency of plasmid transformation only reducing it 20 times. The frequency of transduction of nonmodified plasmid DNA into modifying recipient cells, using phage Ar9 is also reduced a little. The frequency of transduction of chromosomal markers is much more lowered under the same experimental conditions.
Assuntos
Bacillus subtilis/genética , Enzimas de Restrição do DNA/genética , DNA Bacteriano/genética , Plasmídeos , Transdução Genética , Transformação Bacteriana , Marcadores GenéticosRESUMO
Transformation of Bacillus subtilis cells carrying pUB110 plasmid by DNA of homologous plasmid pBD12 results in the significant increase in the number of plasmid transformants. This phenomenon named "augmentation" was not observed when instead of intact cells, regenerating protoplasts were used, or if pBD12 DNA was introduced into the cells via transduction.
Assuntos
Bacillus subtilis/genética , Marcadores Genéticos , Plasmídeos , Transdução Genética , Transformação Bacteriana , DNA Bacteriano/genética , Lisossomos/ultraestrutura , Protoplastos/ultraestruturaRESUMO
Antiplague immunization of mice causes an increase in the number of T-suppressors in their thymus and spleen; this increase is especially pronounced after injection of a low-immunogenic dose of the vaccine strain. T-suppressors specific to Yersinia pestis antigens were detected in the thymus on day 3 after a single injection and on day 14 after two injections of the vaccine strain.
Assuntos
Peste/imunologia , Linfócitos T Reguladores/imunologia , Animais , Especificidade de Anticorpos/imunologia , Antígenos de Bactérias/imunologia , Relação Dose-Resposta Imunológica , Feminino , Tolerância Imunológica/imunologia , Imunidade Celular/imunologia , Masculino , Camundongos , Camundongos Endogâmicos , Vacina contra a Peste/imunologia , Baço/imunologia , Timo/imunologia , Yersinia pestis/imunologiaRESUMO
Immunization with live plague vaccine has been shown to give no protection to thymectomized mice from subcutaneous challenge with Y. pestis virulent strain. Under the action of the vaccine or individual Y. pestis antigens (fraction I) the functional and morphological activation of thymocytes and macrophages is observed, more pronounced in C57BL/6 mice and less pronounced in CBA mice. Y. pestis antigenic preparations (fractions I and II, pesticin) act as T-cell mitogens and are thus capable of inducing the in vitro proliferation of thymocytes. At the same time the in vivo action of fraction II induces a decrease in the level of lymphocytes in the peripheral blood of mice and the destruction of lymphocytes in their thymus and spleen.
Assuntos
Antígenos de Bactérias/imunologia , Peste/imunologia , Yersinia pestis/imunologia , Animais , Antígenos de Bactérias/toxicidade , Vacinas Bacterianas/imunologia , Vacinas Bacterianas/toxicidade , Haplótipos/imunologia , Imunidade Celular/imunologia , Imunização , Camundongos , Camundongos Endogâmicos , Fagócitos/imunologia , Linfócitos T/imunologia , Timo/imunologiaRESUMO
During transformation of B. subtilis cells with the Bsu R restriction-modification system by means of pUB110 plasmid restriction and modification of the plasmid DNA occurs. The effect of restriction on the transformation frequency is relatively weak, bringing about 20-fold decrease only. When using cells of a modifying recipient, the frequency of AR9 phage-mediated transduction of unmodified plasmid DNA is also relatively little decreased. The frequency of transduction by chromosomal markers, under the same conditions, falls much lower.
Assuntos
Bacillus subtilis/genética , DNA Bacteriano/genética , Plasmídeos , Transdução Genética , Transformação Genética , Bacteriófagos/genética , DNA Viral/genética , Marcadores GenéticosRESUMO
Marker rescue in plasmid transformation of competent cells of different rec mutants of B. subtilis was studied. In most cases the value of marker rescue decreased proportionally to reduction of plasmid transformation efficiency (although there were certain exceptions). Marker rescue was not observed either in plasmid transformation of protoplasts or in plasmid transduction of intact cells.