Résumé
Benznidazole (BZ) is one of the two drugs used for Chagas disease treatment. Nevertheless therapeutic failures of BZ have been reported, which were mostly attributed to variable drug susceptibility among Trypanosoma cruzi strains. ATP-binding cassette (ABC) transporters are involved in a variety of translocation processes and some members have been implicated in drug resistance. Here we report the characterisation of the first T. cruzi ABCG transporter gene, named TcABCG1, which is over-expressed in parasite strains naturally resistant to BZ. Comparison of TcABCG1 gene sequence of two TcI BZ-resistant strains with CL Brener BZ-susceptible strain showed several single nucleotide polymorphisms, which determined 11 amino acid changes. CL Brener transfected with TcI transporter genes showed 40-47% increased resistance to BZ, whereas no statistical significant increment in drug resistance was observed when CL Brener was transfected with the homologous gene. Only in the parasites transfected with TcI genes there was 2-2.6-fold increased abundance of TcABCG1 transporter protein. The analysis in wild type strains also suggests that the level of TcABCG1 transporter is related to BZ natural resistance. The characteristics of untranslated regions of TcABCG1 genes of BZ-susceptible and resistant strains were investigated by computational tools.
Sujets)
Animaux , Humains , Transporteurs ABC/génétique , Résistance aux substances/génétique , Nitroimidazoles/pharmacologie , Trypanocides/pharmacologie , Trypanosoma cruzi/effets des médicaments et des substances chimiques , Trypanosoma cruzi/génétique , ADN des protozoaires/génétique , Génotype , Protéines de transport membranaire/génétique , Tests de sensibilité parasitaire , PhylogenèseRésumé
The sequencing of Trypanosoma cruzi genome has been completed and a great deal of information is now available. However, the organization of protozoa genomes is somewhat elusive and much effort must be applied to reveal all the information coded in the nucleotide sequences. Among the DNA segments that needs further investigation are the untranslated regions of genes. Many of the T. cruzi genes that were revealed by the genome sequencing lack information about the untranslated regions. In this paper, some features of these untranslated segments as well as their applications in T. cruzi populations are discussed.
Sujets)
Animaux , Calmoduline/génétique , Gènes de protozoaire/génétique , Mutation , Trypanosoma cruzi/génétique , Régions non traduites/génétique , Calmoduline/composition chimique , Régions non traduites/composition chimiqueRésumé
Data analysis, presentation and distribution is of utmost importance to a genome project. A public domain software, AdDB, has been chosen as the common basis for parasite genome databases, and a first release of TcruziDB, the Trypanosoma cruzi genome database, is available by ftp from ftp://irisdbbm.fiocruz.br/pub/genomedb/TcruziDB as well as versions of the software for different operating systems (ftp://iris.dbbm.fiocruz.br/pub/unixsoft/). Morever, data originated from the project are available from the WWW server at http://www.dbbm.fiocruz.br. It contains biological and parasitological data on CL Brener, its karytype, all available T. cruzi sequences from Genbank, data on th EST-sequencing project and on available libraries, a T. cruzi codon table and a listing of activities and participating groups in the genome project, as well as meeting reports. T. cruzi discussion lists (tcruzi-l@iris.dbbm.fiocruz.br and tcgenics@iris.dbbm.fiocruz.br) being maintained for communication and to promote collaboration in the genome project.
Sujets)
Animaux , Génome de protozoaire , Systèmes d'information , Trypanosoma cruzi/génétique , Réseaux de communication entre ordinateurs , Services d'information , Mémorisation et recherche des informationsRésumé
By using improved pulsed field gel electrophoresis conditions, the molecular karyotype of the reference chromosomal bands ranging in size from 0.45 to 3.5 Magabase pairs (Mbp) were resolved in a single run. The weighted sum of the chromosomal bands was approximately 87 Mbp. Chromoblots were hybridized with 39 different homologous probes, 13 of which identified single chromosomes. Several markers linkage and four different linkage groups were identified, each comprising two markers. Densitometric analysis suggests that most of the chromosomal bands contain two or more chromosomes representing either homologous chromosomes and/or heterologous chromosomes with similar sizes.
Sujets)
Animaux , Cartographie chromosomique , Clones cellulaires , Caryotypage , Trypanosoma cruzi/génétique , Électrophorèse en champ pulsé , Génome de protozoaireRésumé
Random single pass sequencing of cDNA fragments, also known as generation of Expressed Sequence Taggs (ESTs), has been highly successful in the study of the gene content of higher organisms, and forms an integral part of most genome projects, with the objective to identify new genes and targets for disease control and prevention and to generate mapping probes. In the Trypanosoma cruzi genome project, EST sequencing has also been a starting point, and here we report data on the first 797 sequences obtained, partly from a CL Brener epimastigote non-normalized library, partly on a normalized library. Only around 30 per cent of the sequences obtained showed similarity with Genbank and dbEST databases, half of which with sequences already reported for T. cruzi.