RESUMO
As part of the Trypanosoma cruzi Genome Initiative, we have mapped a large portion of the chromosomal bands XVI (2.3 Mb) and XVII (2.6 Mb) containing the highly repetitive and immunodominant antigenic gene families h49 and jl8. Restriction mapping of the isolated chromosomal bands and hybridization with chromosome specific gene probes showed that genes h49 and jl8 are located in a pair of size-polymorphic homologous chromosomes. To construct the integrated map of the chromosomes harboring the h49 and jl8 loci, we used YAC, cosmid, and lambda phage overlapping clones, and long range restriction analysis using a variety of probes (i.e., known gene sequences, ESTs, polymorphic repetitive sequences, anonymous sequences, STSs generated from the YAC ends). The total length covered by the YAC contig was approximately 670 kb, and its map agreed and was complementary to the one obtained by long-range restriction fragment analysis. Average genetic marker spacing in a 105 kb region around h49 and jl8 genes was estimated to be 6.2 kb/marker. We have detected some polymorphism in the H49/JL8 antigens-encoding chromosomes, affecting also the coding regions. The physical map of this region, together with the isolation of specific chromosome markers, will contribute in the global effort to sequence the nuclear genome of this parasite.
Assuntos
Antígenos de Protozoários/genética , Mapeamento Físico do Cromossomo , Trypanosoma cruzi/genética , Animais , Bandeamento Cromossômico , Cromossomos Artificiais de Levedura/genética , Mapeamento de Sequências Contíguas , Sondas de DNA/genética , DNA de Protozoário/química , DNA de Protozoário/isolamento & purificação , Genes de Protozoários/genética , Humanos , Epitopos Imunodominantes/genética , Mapeamento por Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
We report the molecular characterization of a middle repetitive DNA sequence, named C6, isolated from the Trypanosoma cruzi genome. C6 appears to be a composite repeated element since 3 subregions may be defined within it on the basis of sequence similarities with other T. cruzi genomic sequences. Sequences homologous to C6 are interspersed in the genome and can be mapped out on most chromosomal bands of different T. cruzi. strains. The copy number of the C6 element is about 1000 per haploid genome. Given the species specificity and different genomic distribution of C6 homologous sequences among the T. cruzi strains the C6 element could be a useful probe for diagnosis and typing of parasites. C6 is a polymorphic marker with potential as a tool for physical mapping of the T. cruzi genome.
Assuntos
Genoma de Protozoário , Sequências Repetitivas de Ácido Nucleico , Trypanosoma cruzi/genética , Animais , Sequência de Bases , Southern Blotting , Doença de Chagas/diagnóstico , Doença de Chagas/parasitologia , DNA de Protozoário/genética , Eletroforese em Gel de Campo Pulsado , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Polimorfismo Genético/genética , Sequências Repetitivas de Ácido Nucleico/genética , Análise de Sequência de DNA , Especificidade da Espécie , Trypanosoma cruzi/isolamento & purificaçãoRESUMO
A case of decompensated chagasic cardiopathy in a nine-year-old boy from the south of the State of Goiás, is described. He developed congestive heart failure four months before death. The serological reaction for Chagas' disease and the xenodiagnosis were positive. Electrocardiograms showed sinusal tachycardia, ventricular and supraventricular extrasystoles, left anterior hemiblock, complete right bundle branch block and signs of chambers overload. The echocardiogram demonstrated chamber dilatation with diffuse hypocontractility. He presented a downhill course complicated with several pneumonic episodes, the last one just before death. At necropsy, the heart, exhibited a chronic pancarditis with fibrosing chronic myocarditis involving mainly the interventricular septum and left ventricle. The heart conduction system showed slight to moderate exudative, inflammatory changes. Scattered foci of slight chronic periganglionitis and rare degenerative phenomena of ganglionic cells were found in intracardiac autonomic nervous, without neuronal depopulation.
Assuntos
Sistema Nervoso Autônomo/patologia , Cardiomiopatia Chagásica/patologia , Sistema de Condução Cardíaco/patologia , Coração/inervação , Criança , Doença Crônica , Diagnóstico Diferencial , Insuficiência Cardíaca/patologia , Humanos , Masculino , Miocárdio/patologiaRESUMO
A fragment of Trypanosoma cruzi ribosomal intergenic spacer (IGS) located at 6.7 kb from the 3' end of the 24S rRNA gene was analyzed. This IGS fragment is characterized by the presence of three types of repetitive elements (designated Spacer Repetitive Elements, SRE), short direct repeats (5-6 bp) and chi-like recombinational sequences. SRE elements are composed of relatively short repeats (43-145 bp) which show variabilities consisting of nucleotide changes, insertions and deletions. SRE-1 element (145 bp) has a short oligo(dA) tail at the end of the repeat and can be found flanked by other SRE elements. SRE elements are species-specific, suggesting that probes based on them may be diagnostic for Trypanosoma cruzi.
