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Id: lil-228584
Autor: Contreras, I; Obreque, V; Tesser, B; Mora, G. C.
Título: Mini-Mu technology in Salmonella typhi: isolation of stable MudJ operon fusions by cis complementation
Fonte: Biol. Res;27(3/4):233-9, 1994. ilus, tab.
Idioma: en.
Resumo: This paper describes a method to achieve stable MudJ insertions in the Salmonella typhi Ty2 chromosome. The method is a modification of the genetic complementation system described previously for Salmonella typhimurium, which consists in placing the defective transposon (MudJ) near the transposase genes of a helper Mu phage on a single DNA fragment. This fragment is then introduced into a new bacterial host by means of P22 transduction. We constructed a S. typhi strain which carries MudJ and the Mu helper phage in the chromosome. This strain was induced to lytic growth and the lysate was used to infect S. typhi Ty2. The frequency of mutation was 2.0 x 10(-6) mutants per recipient bacterium. Superinfection with the Mu helper phage was about 1 percent. To determine the number of MudJ insertions, several mutants were subjected to Southern blot analysis. From a total of 25 mutants analyzed, only 4 contained more than one insertion. Our procedure compares well with the method described previously for the S. typhimurium-P22 system and can be applied to other Mu sensitive bacteria
Descritores: Bacteriófago mu
Salmonella typhi/genética
Transdução Genética
-Bacteriófago mu/isolamento & purificação
Tipo de Publ: Research Support, Non-U.S. Gov't
Responsável: BR1.1 - BIREME

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Texto completo SciELO Brasil
Castilho, B. A
Texto completo
Id: lil-191348
Autor: Magalhäes, V. D; Castilho, B. A.
Título: Mini-Mu insertions in the tetracycline resistence determinant from proteus mirabilis
Fonte: Braz. j. med. biol. res = Rev. bras. pesqui. méd. biol;30(3):363-7, Mar. 1997. ilus, tab.
Idioma: en.
Resumo: The inducible tetracycline resistance determinant isolated from Proteus mirabilis cloned into the plasmid pACYC177 was mutagenized by insertion of a mini-Mu-lac phage in order to define the regions in the cloned sequences encoding the structural and regulatory proteins. Three different types of mutants were obtained: one lost the resistance phenotype and became Lac+; another expressed the resistance at lowerlevels and constitutively; the third was still dependent on induction but showed a lower minimal inhibitory concentration. The mutant phenotypes and the locations of the insertions indicate that the determinant is composed of a repressor gene and a structural gene which are not transcribed divergently as are other known tetracycline determinants isolated from Gram-negative bacteria.
Descritores: Bacteriófago mu/genética
Óperon Lac
Proteus mirabilis/citologia
Resistência a Tetraciclina/genética
Limites: Animais
Responsável: BR1.1 - BIREME

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