RESUMO
The transcription start point (tsp) of the ribosomal RNA(rRNA)-encoding gene of Trypanosoma cruzi was mapped at 1550 bp upstream from the 18S rRNA coding sequence. The + 1 nucleotide (tsp) was determined to be a guanosine. As described for other eukaryotes, no consensus sequence was found when the putative promoter sequence (-200 to + 50) was compared with that described for Trypanosoma brucei and Crithidia fasciculata. However, a repeated element was found in the upstream intergenic spacer sequence (IGS) of T. cruzi. Motifs, present in this element, exhibit significant homology to the T. cruzi promoter sequence. Furthermore, the same motifs could be found, in a similar sequence organization, within the T. brucei promoter region. Therefore, the data described in this paper strongly indicate that the IGS rDNA (DNA coding for rRNA) organization in trypanosomatids appears similar to that found in higher eukaryotes.
Assuntos
RNA de Protozoário/genética , RNA Ribossômico 18S/genética , Trypanosoma cruzi/genética , Animais , Sequência de Bases , Dados de Sequência Molecular , Regiões Promotoras Genéticas/genética , Sequências Repetitivas de Ácido Nucleico , Homologia de Sequência do Ácido Nucleico , Transcrição Gênica/genéticaRESUMO
The ribosomal RNA genes of two species of Trypanosoma, Trypanosoma cruzi, the etiological agent of Chagas' disease, and Trypanosoma conorhini, a non-pathogenic rodent trypanosome, were cloned and partially characterized. The physical maps derived for their rRNA genes were similar throughout the region that encompasses the SSU-and LSU-rRNA coding sequences. However, the non-transcribed spacer DNA of both T. cruzi and T. conorhini was found to be polymorphic for several restriction enzyme sites. We show that strains of T. cruzi can be typed according to the characteristic restriction fragment length polymorphism of their NTS DNAs.
Assuntos
Polimorfismo de Fragmento de Restrição , RNA Ribossômico/química , Trypanosoma cruzi/genética , Trypanosoma/genética , Animais , Clonagem Molecular , DNA de Protozoário/química , DNA Ribossômico/química , Mapeamento por RestriçãoRESUMO
1. In the tetraploid amphibian Odontophrynus americanus the selective precipitation of vitellogenin by Mg2+ from plasma treated with ethylene diaminetetraacetic acid (EDTA) or ethylene bis (oxyethylenenitrilo)-tetraacetic acid (EGTA) is a pH-dependent phenomenon. 2. Utilizing sucrose gradient centrifugation of whole plasma we have shown that under standard conditions (pH 7.0) the estimated apparent sedimentation coefficient of vitellogenin is 17S. At pH 8.0 and in the presence of EDTA or EGTA there is a decrease of the vitellogenin sedimentation coefficient. This behavior is restricted to vitellogenin as other plasma proteins show no alteration in their sedimentation coefficient after similar treatment. 3. The treatment with EDTA at pH 8.0 also induces changes in the vitellogenin molecule which can be detected by partial proteolysis with chymotrypsin A.
Assuntos
Ácido Edético/farmacologia , Concentração de Íons de Hidrogênio , Magnésio/farmacologia , Vitelogeninas/isolamento & purificação , Anfíbios , Animais , Centrifugação com Gradiente de Concentração , Cromatografia por Troca Iônica , Eletroforese em Gel de Poliacrilamida , Masculino , Conformação Molecular , Vitelogeninas/sangue , Vitelogeninas/químicaRESUMO
The analysis of PvuII restriction patterns of Leishmania spp. and Trypanosoma spp. genomic DNA showed genus distinctive profiles. A specific PvuII site was detected in the 5' domain of 18S ribosomal DNA of Leishmania. A 20-mer oligonucleotide encompassing this PvuII region was synthesized. This sequence, when utilized as probe, on short exposures of dot tests, detected 10(3) whole promastigotes of all Leishmania species analyzed but did not hybridize with T. cruzi or human nucleic acids. Two other oligonucleotides were synthesized to be used as primers for amplification through polymerase chain reaction of the 18S ribosomal DNA region containing the PvuII site. The probes described may be useful for the detection of Leishmania spp. under clinical and epidemiological trials.
Assuntos
DNA Ribossômico/análise , Leishmania/classificação , RNA Ribossômico 18S/análise , Animais , Sequência de Bases , Southern Blotting , DNA de Protozoário/análise , Desoxirribonucleases de Sítio Específico do Tipo II , Leishmania/genética , Leishmania/isolamento & purificação , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Sondas de Oligonucleotídeos , Reação em Cadeia da Polimerase , Valor Preditivo dos Testes , RNA de Protozoário/análise , Mapeamento por RestriçãoRESUMO
In a study of enterotoxigenic strains of Escherichia coli isolated from children with diarrhea in São Paulo, Brazil, a new enterotoxin and antibiotic resistance plasmid that carries heat-labile toxin, heat-stable toxin, and drug resistance genes was found. This is the first such plasmid to be found in a human strain of E. coli. The plasmid is nonconjugative, has a molecular weight of at least 54 x 10(6), and is mobilized by the R plasmid present in the host strain.
Assuntos
Toxinas Bacterianas , Enterotoxinas/genética , Proteínas de Escherichia coli , Escherichia coli/genética , Plasmídeos , Fatores R , Antibacterianos/farmacologia , Colicinas/genética , Conjugação Genética , Escherichia coli/efeitos dos fármacos , Humanos , Peso MolecularRESUMO
The vitellogenin of Odontophrynus americanus is a large (426.5 kDa) plasmatic protein. The vitellogenin is composed of two different phosphoglycopeptides: VTG1 = 207.5 kDa and VTG2 = 202.4 kDa. The vitellins originating from the partial proteolysis of the plasmatic vitellogenin on the ovary cells are composed of lipovitellins and phosphoproteins. Lipovitellin 1 has two glycopeptides with different amino acid sequences as determined by peptide mapping (LV1 alpha, 104.6 kDa; and LV1 beta, 92.6 kDa). Lipovitellin 2 is composed of three kinds of polypeptides (LV2 alpha, 31.7 kDa; LV2 beta, 29.7 kDa; LV2 gamma, 27.8 kDa). There are three phosphopeptides in the yolk: phosvitin (PV, 37.4 kDa) and phosvettes 1 (PVT1, 27.7 kDa) and 2 (PVT2, 26.1 kDa).
Assuntos
Anuros , Proteínas Dietéticas do Ovo , Precursores de Proteínas/sangue , Vitelogeninas/biossíntese , Animais , Proteínas do Ovo/isolamento & purificação , Gema de Ovo , Eletroforese em Gel de Poliacrilamida , Estradiol/farmacologia , Glicopeptídeos/análise , Fragmentos de Peptídeos/análise , Fosfopeptídeos/análise , Vitelogeninas/isolamento & purificaçãoRESUMO
Dezoito amostras de Escherichia coli produtoras de toxina LT, isoladas de criancas, foram estudadas em relacao a resistencia a drogas e producao de colicinas, hemolisinas e H2S. Oito amostras eram sensiveis as drogas utilizadas e negativas em relacao as demais caracteristicas. Uma amostra somente produziu colicina. As outras nove linhagens apresentaram diferentes padroes de resistencia (1 a 7 drogas) e uma delas tambem produziu colicina. Foi observado atraves de experimentos de conjugacao que em seis dessas amostras os plasmidios R eram transferidos e 4 delas tambem transferiam o plasmidio Ent. A producao de colicina pelos transconjugantes so foi observada atraves de estudos de cotransferencia. Esses estudos e eletroforese em gel de agarose mostraram que nas seis amostras os genes que cidificam para LT, colicinas e resistencia a drogas estao localizados em plasmidios independentes.Foi observado que a transferencia de plasmidios R ocorreu nas 4 amostras e do plasmidio Ent em 3 das amostras resistentes, isoladas de criancas com diarreia enquanto que a transferencia desses plasmidios e menor entre as amostras resistentes isoladas de criancas sadias