RESUMEN
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.
Asunto(s)
ARN Protozoario/genética , ARN Ribosómico 18S/genética , Trypanosoma cruzi/genética , Animales , Secuencia de Bases , Datos de Secuencia Molecular , Regiones Promotoras Genéticas/genética , Secuencias Repetitivas de Ácidos Nucleicos , Homología de Secuencia de Ácido Nucleico , Transcripción Genética/genéticaRESUMEN
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.
Asunto(s)
ADN Ribosómico/análisis , Leishmania/clasificación , ARN Ribosómico 18S/análisis , Animales , Secuencia de Bases , Southern Blotting , ADN Protozoario/análisis , Desoxirribonucleasas de Localización Especificada Tipo II , Leishmania/genética , Leishmania/aislamiento & purificación , Datos de Secuencia Molecular , Hibridación de Ácido Nucleico , Sondas de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Valor Predictivo de las Pruebas , ARN Protozoario/análisis , Mapeo RestrictivoRESUMEN
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.
Asunto(s)
Ácido Edético/farmacología , Concentración de Iones de Hidrógeno , Magnesio/farmacología , Vitelogeninas/aislamiento & purificación , Anfibios , Animales , Centrifugación por Gradiente de Densidad , Cromatografía por Intercambio Iónico , Electroforesis en Gel de Poliacrilamida , Masculino , Conformación Molecular , Vitelogeninas/sangre , Vitelogeninas/químicaRESUMEN
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.
Asunto(s)
Polimorfismo de Longitud del Fragmento de Restricción , ARN Ribosómico/química , Trypanosoma cruzi/genética , Trypanosoma/genética , Animales , Clonación Molecular , ADN Protozoario/química , ADN Ribosómico/química , Mapeo RestrictivoRESUMEN
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).
Asunto(s)
Anuros , Proteínas Dietéticas del Huevo , Precursores de Proteínas/sangre , Vitelogeninas/biosíntesis , Animales , Proteínas del Huevo/aislamiento & purificación , Yema de Huevo , Electroforesis en Gel de Poliacrilamida , Estradiol/farmacología , Glicopéptidos/análisis , Fragmentos de Péptidos/análisis , Fosfopéptidos/análisis , Vitelogeninas/aislamiento & purificaciónRESUMEN
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.
Asunto(s)
Toxinas Bacterianas , Enterotoxinas/genética , Proteínas de Escherichia coli , Escherichia coli/genética , Plásmidos , Factores R , Antibacterianos/farmacología , Colicinas/genética , Conjugación Genética , Escherichia coli/efectos de los fármacos , Humanos , Peso MolecularRESUMEN
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