title: DNA markers define two major phylogenetic lineages of Trypanosoma cruzi.
abstract: Parasitic protozoa within the taxon Trypanosoma cruzi are considered to be derived from multiple clonal lineages, and show broad genetic diversity as a result of propagation with little or no genetic exchange. We have analyzed a wide sample of T. cruzi isolates from vertebrate and invertebrate hosts by PCR amplification of a ribosomal RNA gene sequence, a mini-exon gene sequence and random amplified polymorphic DNA (RAPD). Amplification of the distinct rDNA and mini-exon gene sequences indicated a dimorphism within both of the tandemly-repeated genes: 125 or 110 bp products for rDNA and 300 or 350 bp products for the mini-exon. Within individual isolates, one of three associations was observed: the 125 bp rDNA product with the 300 bp mini-exon product (defined as group 1), the 110 bp rDNA product with the 350 bp mini-exon product (defined as group 2) and the presence of both rDNA amplification products with the mini-exon group 1 product (group 1/2). The RAPD analysis showed variability between individual isolates, however, tree analysis clearly indicated the presence of two major branches. Interestingly, the rDNA/mini-exon group 2 isolates correlated precisely with one branch of the RAPD-derived tree; group 1 and group 1/2 isolates correlated with the other branch. Our studies show a clear division of T. cruzi into two major lineages presenting a high phylogenetic divergence. Hypotheses are discussed to explain the origin of the two lineages as well as isolates that are hybrid for group 1 and 2 rDNA markers.
authors.affiliation: Departamento de Bioquímica, Universidade de São Paulo, Brazil.
authors.forename: R P
authors.initials: RP
authors.lastname: Souto
authors.forename: O
authors.initials: O
authors.lastname: Fernandes
authors.forename: A M
authors.initials: AM
authors.lastname: Macedo
authors.forename: D A
authors.initials: DA
authors.lastname: Campbell
authors.forename: B
authors.initials: B
authors.lastname: Zingales
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics*; D005091:Exons / Q000235:genetics; D005819:Genetic Markers; D008969:Molecular Sequence Data; D010802:Phylogeny; D016053:RNA, Protozoan / Q000235:genetics; D019105:Random Amplified Polymorphic DNA Technique; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014349:Trypanosoma cruzi / Q000235:genetics*
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D005819:Genetic Markers; D016053:RNA, Protozoan