title: Ancestral genomes, sex, and the population structure of Trypanosoma cruzi.
abstract: Acquisition of detailed knowledge of the structure and evolution of Trypanosoma cruzi populations is essential for control of Chagas disease. We profiled 75 strains of the parasite with five nuclear microsatellite loci, 24Salpha RNA genes, and sequence polymorphisms in the mitochondrial cytochrome oxidase subunit II gene. We also used sequences available in GenBank for the mitochondrial genes cytochrome B and NADH dehydrogenase subunit 1. A multidimensional scaling plot (MDS) based in microsatellite data divided the parasites into four clusters corresponding to T. cruzi I (MDS-cluster A), T. cruzi II (MDS-cluster C), a third group of T. cruzi strains (MDS-cluster B), and hybrid strains (MDS-cluster BH). The first two clusters matched respectively mitochondrial clades A and C, while the other two belonged to mitochondrial clade B. The 24Salpha rDNA and microsatellite profiling data were combined into multilocus genotypes that were analyzed by the haplotype reconstruction program PHASE. We identified 141 haplotypes that were clearly distributed into three haplogroups (X, Y, and Z). All strains belonging to T. cruzi I (MDS-cluster A) were Z/Z, the T. cruzi II strains (MDS-cluster C) were Y/Y, and those belonging to MDS-cluster B (unclassified T. cruzi) had X/X haplogroup genotypes. The strains grouped in the MDS-cluster BH were X/Y, confirming their hybrid character. Based on these results we propose the following minimal scenario for T. cruzi evolution. In a distant past there were at a minimum three ancestral lineages that we may call, respectively, T. cruzi I, T. cruzi II, and T. cruzi III. At least two hybridization events involving T. cruzi II and T. cruzi III produced evolutionarily viable progeny. In both events, the mitochondrial recipient (as identified by the mitochondrial clade of the hybrid strains) was T. cruzi II and the mitochondrial donor was T. cruzi III.
authors.affiliation: Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
authors.forename: Jorge M
authors.initials: JM
authors.lastname: de Freitas
authors.forename: Luiz
authors.initials: L
authors.lastname: Augusto-Pinto
authors.forename: Juliana R
authors.initials: JR
authors.lastname: Pimenta
authors.forename: Luciana
authors.initials: L
authors.lastname: Bastos-Rodrigues
authors.forename: Vanessa F
authors.initials: VF
authors.lastname: Gonçalves
authors.forename: Santuza M R
authors.initials: SM
authors.lastname: Teixeira
authors.forename: Egler
authors.initials: E
authors.lastname: Chiari
authors.forename: Angela C V
authors.initials: AC
authors.lastname: Junqueira
authors.forename: Octavio
authors.initials: O
authors.lastname: Fernandes
authors.forename: Andréa M
authors.initials: AM
authors.lastname: Macedo
authors.forename: Carlos Renato
authors.initials: CR
authors.lastname: Machado
authors.forename: Sérgio D J
authors.initials: SD
authors.lastname: Pena
mesh_terms: D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D050259:Genes, Mitochondrial; D005819:Genetic Markers; D005828:Genetics, Population; D018503:Genome, Protozoan; D005838:Genotype; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D010802:Phylogeny; D012737:Sex Factors; D014349:Trypanosoma cruzi / Q000235:genetics*
chemical_list: D005819:Genetic Markers