RESUMO
We studied the effect of the organoselenium compound 2,6-dipyridinium-9-selenium-bicyclo[ 3,3,1]nonan dibromide (974zh) on the severity of pathological changes in the organs of experimental animals immunized with live tularemia and brucellosis vaccines. It was found that 974zh reduced reactogenicity of vaccines for experimental animals. Our findings indicate the prospects for further studies of the effects of 974zh on the functional state of experimental animals.
Assuntos
Vacinas Bacterianas/imunologia , Brucelose/imunologia , Compostos Organosselênicos/farmacologia , Medicamentos Sintéticos/farmacologia , Tularemia/imunologia , Animais , Espectroscopia de Ressonância Magnética , CamundongosRESUMO
The dynamics of LPO marker malondialdehyde formation and peroxidase-destroying activity was studied in homogenized organs of guinea pigs, immunized with thermoextracts from S and L forms Brucella abortus I-206. The L form brucella thermoextract exhibited a lower reactogenicity and adequately activated the antioxidant system, due to which the destructive effects of ROS could be partially neutralized during the vaccinal process.
Assuntos
Estruturas Animais/efeitos dos fármacos , Antioxidantes/metabolismo , Vacina contra Brucelose/farmacologia , Brucella abortus/química , Peroxidação de Lipídeos/efeitos dos fármacos , Vacinas Atenuadas/farmacologia , Estruturas Animais/metabolismo , Animais , Animais de Laboratório , Vacina contra Brucelose/química , Brucella abortus/imunologia , Brucella abortus/patogenicidade , Feminino , Cobaias , Formas L/fisiologia , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Masculino , Estresse Oxidativo/efeitos dos fármacos , Esferoplastos/fisiologia , Temperatura , Vacinas Atenuadas/químicaRESUMO
This paper reports the discovery and characterization of Tn5041, a novel-type transposon vehicle for dissemination of mercury resistance in natural bacterial populations. Tn5041 (14876 bp), identified in a Pseudomonas strain from a mercury mine, is a Tn3 family mercury resistance transposon far outside the Tn21 subgroup. As in other Tn3 family transposons, Tn5041 duplicates 5 bp of the target sequence following insertion. Tn5041 apparently acquired its mer operon as a single-ended relic of a transposon belonging to the classical mercury resistance transposons of the Tn21 subgroup. The putative transposase and the 47 bp terminal inverted repeats of Tn5041 are closely related to those of the toluene degradative transposon Tn4651 and fall into a distinct subgroup on the fringe of the Tn3 family. The amino acid sequence of the putative resolvase of Tn5041 resembles site-specific recombinases of the integrase family. Besides the mer operon and putative transposition genes, Tn5041 contains a 4 kb region that accommodates a number of apparently defective genes and mobile elements.
Assuntos
Elementos de DNA Transponíveis/genética , Integrases , Mercúrio/farmacologia , Pseudomonas/genética , Transposon Resolvases , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Sequência de Bases , Biodegradação Ambiental , Quimera , Clonagem Molecular , DNA Nucleotidiltransferases/genética , Resistência Microbiana a Medicamentos/genética , Escherichia coli/genética , Evolução Molecular , Genes Bacterianos , Dados de Sequência Molecular , Óperon , Pseudomonas/efeitos dos fármacos , Recombinases , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Tolueno/metabolismoRESUMO
The complete nucleotide sequence of an 8447 bp-long mercury-resistance transposon (Tn5053) has been determined. Tn5053 is composed of two modules: (i) the mercury-resistance module and (ii) the transposition module. The mercury-resistance module carries a mer operon, merRTPFAD, and appears to be a single-ended relic of a transposon closely related to the classical mercury-resistance transposons Tn21 and Tn501. The transposition module of Tn5053 is bounded by 25 bp terminal inverted repeats and contains four genes involved in transposition, i.e. tniA, tniB, tniQ, and tniR. Transposition of Tn5053 occurs via cointegrate formation mediated by the products of the tniABQ genes, followed by site-specific cointegrate resolution. This is catalysed by the product of the tniR gene at the res region, which is located upstream of tniR. The same pathway of transposition is used by Tn402 (Tn5090) which carries the integron of R751. Transposition genes of Tn5053 and Tn402 are interchangeable. Sequence analysis suggests that Tn5053 and Tn402 are representatives of a new family of transposable elements, which fall into a recently recognized super-family of transposons including retroviruses, insertion sequences of the IS3 family, and transposons Tn552 and Tn7. We suggest that the tni genes were involved in the dissemination of integrons.
Assuntos
Proteínas de Bactérias/genética , Proteínas de Transporte/genética , DNA Nucleotidiltransferases/genética , Elementos de DNA Transponíveis/genética , Genes Bacterianos , Óperon/genética , Sequência de Aminoácidos , Proteínas de Bactérias/fisiologia , Sequência de Bases , Proteínas de Transporte/fisiologia , Clonagem Molecular , Sequência Consenso , DNA Nucleotidiltransferases/fisiologia , Elementos de DNA Transponíveis/fisiologia , Resistência Microbiana a Medicamentos/genética , Escherichia coli/genética , Peptídeos e Proteínas de Sinalização Intracelular , Mercúrio/farmacologia , Dados de Sequência Molecular , TransposasesRESUMO
We present the complete nucleotide sequence of a mer operon located on a 60-kb conjugative plasmid pKLH2 from an environmental bacterium, Acinetobacter calcoaceticus, isolated from a mercury mine. The pKLH2 mer operon has essentially the same gene organization as that of Tn21 and Tn501 from clinical bacteria. The pKLH2 mer operon nucleotide sequence shows 85.5% identity with the Tn501 and 80.9% identity with the Tn21 sequences. Vestigial sequences have been found at the ends of the pKLH2 mer operon, indicating that the pKLH2 mer operon was once a part of a Tn21-like transposon, which had committed suicide by an aberrant resolution event.
Assuntos
Acinetobacter/genética , Elementos de DNA Transponíveis , Resistência Microbiana a Medicamentos/genética , Fator F/genética , Genes Bacterianos , Mercúrio/toxicidade , Óperon , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/genética , Sequência de Bases , Conjugação Genética , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Dados de Sequência Molecular , Nucleotidiltransferases/metabolismo , Mapeamento por Restrição , Homologia de Sequência do Ácido Nucleico , TransposasesRESUMO
We describe a novel type of mercury resistance transposon, Tn5053, which was found in the chromosome of a mercury-resistant Xanthomonas strain isolated from a mercury mine. An 8400 base-pair Tn5053 is bracketed by 25 base-pair inverted repeats that have no sequence homology with inverted repeats of classical mercury resistance transposons Tn501 and Tn21. Instead they show high homology with inverted repeats bracketing the antibiotic resistance segment of Tn21 (integron In2). A 38 base-pair element, which is highly homologous to the inverted repeats of classical mercury resistance transposons has been found within Tn5053 near one of its ends. This internal inverted repeat is fused to the mer operon of Tn5053 in exactly the same way as in the Tn501 mercury resistance transposon. This finding suggests that the mer operon was integrated into the Tn5053 transposition module not through integron-specific pathway but rather via insertion of a classical mercury resistance transposon.
Assuntos
Elementos de DNA Transponíveis/genética , Mercúrio/farmacologia , Xanthomonas/genética , Sequência de Bases , Resistência Microbiana a Medicamentos/genética , Dados de Sequência Molecular , Óperon/genética , Recombinação Genética , Sequências Repetitivas de Ácido Nucleico/genética , Mapeamento por Restrição , Homologia de Sequência do Ácido Nucleico , Xanthomonas/efeitos dos fármacosRESUMO
We present data on the frequencies of nucleotides and nucleotide substitutions in conservative DNA regions involved in the regulation of gene expression. Data on prokaryotes and eukaryotes are considered separately. In both cases DNA strands complementary to those which serve as templates for RNA-polymerase have low frequencies of cytosine. The most conservative positions also have an increased frequency of adenine. Various substitutions in the series of homologous regulatory DNA sequences, as compared to their consensuses, have different frequencies. In prokaryotes guanine in a consensus sequence is substituted for at the lowest and adenine at the highest frequency, whereas in eukaryotes cytosine is substituted for at the lowest and guanine at the highest frequency. In both cases the nucleotides substituted for are most frequently replaced with cytosine. Deviations from consensus sequences tend to cluster in adjacent positions. The more pronounced the consequences of a nucleotide substitution are the higher is the frequency of substitutions in adjacent positions. Possible explanations for these phenomena are discussed.