RESUMEN
A number of conjugative plasmids of opportunistic E. coli with molecular weights of 23.6--81.8 megadaltons have been studied. On the basis of the data thus obtained conjugative F-like R-plastmids have been subdivided into 2 groups characterized by the unsuppressed or suppressed manifestation of their functions. Individual conjugative plasmids have been found to differ in their capacity for mobilizing non-conjugative SuSm plasmid for transfer, which indicates the possibility of using this test for characterization and classification of plasmids, identified in natural bacterial population.
Asunto(s)
Infecciones por Escherichia coli/microbiología , Escherichia coli/genética , Plásmidos , Animales , Clasificación , Conjugación Genética , Infecciones por Escherichia coli/veterinaria , Peso Molecular , Factores R , Supresión GenéticaRESUMEN
A study was made of compatibility of three F-like factors of the genetic transfer (pAP22-4, pAP39, pAP41) identified in the cells of serologically typed E. coli strains with F-group incompatibility reference plasmids. The factors of pAP22-4 and pAP41 transfer are partly incompatible with groups FII, FIII, FIV, and FI, FIV, respectively, while the factors of pAP39 transfer are completely incompatible both with groups FI and FIV plasmids.
Asunto(s)
Escherichia coli/genética , Factor F , Plásmidos , Clonación Molecular , Elementos Transponibles de ADN , Farmacorresistencia Microbiana , Marcadores Genéticos , MutaciónRESUMEN
The study on 63 strains of conditionally pathogenic E. coli isolated from patients with chronic pyelonephritis showed that the bacteria of the 47 strains (74.6%) were resistant to one or several antibiotics. 7 strains of such bacteria carried R-plasmids capable of transferring into the cells of E. coli K-12 during conjugation. Most of the identified 9 R-plasmids belonged to the class of the F-like plasmids and were characterized by similar lots of antibiotic resistance markers. DNA of the detected R-plasmids were treated with endonuclease (restrictase) EcoRI. After that the fragments were analysed by means of electrophoresis in agarose gel. On the basis of the restrictogrames it was concluded that the plasmids studied were not identical. A possibility of detecting complexes consisting of different plasmids carrying similar lots of antibiotic resistance markers in the cells of the same strain was shown.
Asunto(s)
Conjugación Genética , Escherichia coli/genética , Plásmidos , Pielonefritis/microbiología , Factores R , Fenómenos Químicos , Química Física , Enfermedad Crónica , ADN Bacteriano/genética , Escherichia coli/patogenicidad , Humanos , Orina/microbiologíaRESUMEN
The effect of different concentrations of beta-indoleacetic acid (IAA) on RNA and protein synthesis and the stability of associations of E. coli ribosomes at 3 mM Mg2+ was investigated. IAA in a concentration of 100 microgram/ml had a slight stimulatory effect on the incorporation of [14C]leucine into proteins and stimulated the incorporation of [14C]uracil into the RNA of intact cells more noticeably. In the presence of 2500 microgram/ml of the auxin RNA synthesis was inhibited by 65% and protein synthesis by 40-50% as compared to the control. In a cell-free system containing poly(U) IAA in concentrations of 10-100 microgram/ml increased polyphenylalanine synthesis by an average of 30%, while at high concentrations IAA noticeably inhibited its synthesis. It was found that the proportion of stable ribosomes in lysates obtained from cells incubated with IAA in concentrations of 250 and 1000 microgram/ml decreased to 18 and 3%. It is suggested that the inhibition of protein synthesis in E. coli by IAA is due to inhibition of the initiation of translation.
Asunto(s)
Proteínas Bacterianas/biosíntesis , Escherichia coli/metabolismo , Ácidos Indolacéticos/farmacología , ARN Bacteriano/biosíntesis , Sistema Libre de Células , Leucina/metabolismo , Biosíntesis de Proteínas/efectos de los fármacos , Ribosomas/efectos de los fármacos , Uracilo/metabolismoAsunto(s)
Proteínas Bacterianas/biosíntesis , Escherichia coli/efectos de los fármacos , Ácidos Indolacéticos/farmacología , ARN Bacteriano/biosíntesis , Permeabilidad de la Membrana Celular/efectos de los fármacos , Dactinomicina/farmacología , Relación Dosis-Respuesta a Droga , Interacciones Farmacológicas , Escherichia coli/metabolismoRESUMEN
The author reports of the achieved results in a quantitative study of general lipids, phospholipids and cerebrosides in the CSF of 37 patients with demyelinating diseases, of 11 patients with vascular brain pathology and 7 with Van Bogart's panencephalitis. The control group consisted of 14 patients without focal lesions of the nervous system, with normal CSF indices. In demyelinating diseases there was a significant increase in the content of kephalines and cerebrosides. In Van Bogart's panencephalitis there was a much higher increase of kephalines, general lipids and phospholipids. In vascular brain disorders there was a moderate increase of all lipids. The possible pathochemical mechanisms of the depicted changes in the content of the lipids in the CSF are discussed.