Chromosomal polymorphism, gene synteny and genome size in T. cruzi I and T. cruzi II groups

Vargas, Nancy; Pedroso, Aurélio; Zingales, Bianca

doi:10.1016/j.molbiopara.2004.08.005

Cited by 67 publications

(71 citation statements)

References 36 publications

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“…cruzi is considered to be minimally diploid (Gibson and Miles 1986), but aneuploid in hybrid strains (Vargas et al 2004). In the following sections, we examine the allelic structure of nine loci in the six DTUs of T. cruzi.…”

Section: Resultsmentioning

confidence: 99%

Two Hybridization Events Define the Population Structure of Trypanosoma cruzi

et al. 2005

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Genetic variation in Trypanosoma cruzi is likely a key determinant in transmission and pathogenesis of Chagas disease. We have examined nine loci as markers for the extant T. cruzi strains. Four distinct alleles were found for each locus, corresponding to the sequence classes present in the homozygous discrete typing units (DTUs) I, IIa, IIb, and IIc. The alleles in DTUs IIa and IIc showed a spectrum of polymorphism ranging from DTU I-like to DTU IIb-like, in addition to DTU-specific sequence variation. DTUs IId and IIe were indistinguishable, showing DTU homozygosity at one locus and heterozygosity with DTU IIb and IIc allelic sequences at eight loci. Recombination between the DTU IIb and IIc alleles is evidenced from mosaic polymorphisms. These data imply that two discrete hybridization events resulted in the formation of the current DTUs. We propose a model in which a fusion between ancestral DTU I and IIb strains gave rise to a heterozygous hybrid that homogenized its genome to become the homozygous progenitor of DTUs IIa and IIc. The second hybridization between DTU IIb and IIc strains that generated DTUs IId and IIe resulted in extensive heterozygosity with subsequent recombination of parental genotypes.

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Section: Resultsmentioning

confidence: 99%

Two Hybridization Events Define the Population Structure of Trypanosoma cruzi

et al. 2005

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“…The five gene classes were identified in CL Brener chromosomal bands from 685 to 2996 kb (SSU rDNA -1350 kb; EF-1α -1180 and 1770 kb; actin -685 and 2350 kb; DHFR-TS -1110 and 1030 kb, and TR -2996 kb) Vargas et al, 2004). The alignments generated here include sequences determined in this work and downloaded from GenBank (upon request marcelo.briones@unifesp.br).…”

Section: Genetic Diversity Of Trypanosoma Cruzimentioning

confidence: 99%

“…We determined the sequences of SSU rDNA, elongation factor-1 alpha (EF-1α) and actin of 26 strains, and DHFR-TS and TR genes of 11 strains, including the hybrids of rDNA 1/2 and Z3 subgroups and CL Brener strain. Because SSU rDNA, EF-1α, actin, DHFR-TS and TR genes are localized in different and distant regions of the T. cruzi genome Vargas et al, 2004), it was expected that under a strict clonal dynamics these genes would show consistent evolutionary patterns, whereas hybrids would be observed by inconsistent patterns depending on the marker. Also, the analysis of polymorphism between the T. cruzi groups could support the hybrid pattern and Trypanosoma cruzi hybrids are polyphyletic provide hints on the general mechanism of hybridization.…”

Section: Introductionmentioning

confidence: 99%

“…The phylogenetic patterns inferred here support the existence of hybrid groups that do not form a natural clade, in other words, are not monophyletic. We propose that T. cruzi is in fact synonymous with two different species, T. cruzi I and T. cruzi II, which occasionally form stable hybrids, sometimes polyploids Vargas et al, 2004) with sufficient fitness in the hybrid zone niches (Barton, 2001) to be represented in regular epidemiological sampling.…”

Section: Introductionmentioning

confidence: 99%

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Haplotype distribution of five nuclear genes based on network genealogies and Bayesian inference indicates that Trypanosoma cruzi hybrid strains are polyphyletic

Tomazi¹,

Kawashita²,

Pereira³

et al. 2009

Genet. Mol. Res.

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ABStRAct. Chagas disease is still a major public health problem in Latin America. Its causative agent, Trypanosoma cruzi, can be typed into three major groups, T. cruzi I, T. cruzi II and hybrids. These groups each have specific genetic characteristics and epidemiological distributions. Several highly virulent strains are found in the hybrid group; their origin is still a matter of debate. The null hypothesis is that the hybrids are of polyphyletic origin, evolving independently from various hybridization events. The alternative hypothesis is that all extant hybrid strains originated from a single hybridization event. We sequenced both alleles of genes encoding EF-1α, actin and SSU rDNA of 26 T. cruzi strains and DHFR-TS and TR of 12 strains. This information was used for network genealogy analysis and Bayesian phylogenies. We found T. cruzi I and T. cruzi II to be monophyletic and that all hybrids had different combinations of T. cruzi I and T. cruzi II haplotypes plus hybrid-specif- Trypanosoma cruzi hybrids are polyphyletic ic haplotypes. Bootstrap values (networks) and posterior probabilities (Bayesian phylogenies) of clades supporting the monophyly of hybrids were far below the 95% confidence interval, indicating that the hybrid group is polyphyletic. We hypothesize that T. cruzi I and T. cruzi II are two different species and that the hybrids are extant representatives of independent events of genome hybridization, which sporadically have sufficient fitness to impact on the epidemiology of Chagas disease.

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“…More recently, Weatherly et al (2009) generated consensus versions of each homologous chromosome pair using synteny maps for the T. brucei chromosomes. Ultimately, 41 chromosomes were assembled, which is well above the predicted number of T. cruzi chromosomes based on the early studies of pulsed-field gel electrophoresis analyses (Cano et al 1995, Vargas et al 2004. Although separated by hundreds of millions of years of evolution, genome organisation in T. cruzi is largely syntenic with the other two trypanosomatid genomes, collectively known as the Tri-Tryp genomes (T. brucei and L. major), and most of the species-specific genes, such as large surface protein gene families, occur at non-syntenic chromosome-internal and subtelomeric regions (El-Sayed et al 2005b).…”

mentioning

confidence: 92%

Regulatory elements involved in the post-transcriptional control of stage-specific gene expression in Trypanosoma cruzi: a review

Araújo

Teixeira

2011

Mem. Inst. Oswaldo Cruz

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Trypanosoma cruzi is an intracellular parasite that is transmitted by at least 40 different blood-sucking triatomine species to over 1,000 mammalian species (Brener et al. 2000). This parasite must adapt to enormous changes in its extracellular milieu, such as changes in environmental temperature as well as in the available nutrients inside each host. The parasite has a complex life cycle that is characterised by four stages; epimastigotes and metacyclic trypomastigotes are present in the insect vector, whereas intracellular amastigotes and bloodstream trypomastigotes are present in the mammalian host. Thus, this species must develop a broad set of molecular tools that allow it to multiply in the insect gut, to invade and multiply inside a large number of distinct mammalian cell types and to circumvent host immune defence systems. To meet such phenotypic plasticity, T. cruzi relies on unique mechanisms that can control the expression of its repertoire of about 12,000 genes. Because its genome is constitutively transcribed into long polycistronic primary transcripts, mRNAs for proteincoding genes must be processed through trans-splicing and polyadenylation reactions. The mRNAs must also interact with different protein factors in a complex posttranscriptional regulatory machinery that determines the levels of their protein product according to the cellular demands of the parasite in each stage of its life cycle.In the same issue that the T. cruzi genome was published (El-Sayed et al. 2005a), a study describing its proteome was also reported (Atwood et al. 2005). Proteins extracted from whole-cell and subcellular lysates of the four stages of T. cruzi were analysed by mass spectrometry (epimastigotes, metacyclic trypomastigotes, amastigotes and trypomastigotes), which identified 2,784 proteins belonging to the 1,168 protein groups in the annotated T. cruzi genome. Although about 30% of the identified proteins were found at all life-cycle stages, at least 248 proteins were only expressed at one stage, thereby demonstrating significant changes in the relative abundance of T. cruzi proteins throughout its life cycle. One of the main findings in these proteomic analyses was that the four parasite stages use distinct energy sources (Atwood et al. 2005); intracellular amastigotes upregulated proteins involved in lipid-dependent energy metabolism, such as enzymes of the citric acid cycle, whereas enzymes capable of catalysing the conversion of histidine to glutamate were more abundant in the insect epimastigote stage. Heat-shock proteins (HSP) and proteins involved in vesicular trafficking were also preferentially detected in amastigotes. Furthermore, enzymes involved in antioxidant defence were upregulated during the transformation of epimastigotes into invasive metacyclic trypomastigotes, whereas bloodstream trypomastigotes upregulated the surface expression of several large gene families that are known to be involved in interacting with the mammalian host (Atwood et al. 2005).In agreement with this proteomics data, glo...

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Chromosomal polymorphism, gene synteny and genome size in T. cruzi I and T. cruzi II groups

Cited by 67 publications

References 36 publications

Two Hybridization Events Define the Population Structure of Trypanosoma cruzi

Two Hybridization Events Define the Population Structure of Trypanosoma cruzi

Haplotype distribution of five nuclear genes based on network genealogies and Bayesian inference indicates that Trypanosoma cruzi hybrid strains are polyphyletic

Regulatory elements involved in the post-transcriptional control of stage-specific gene expression in Trypanosoma cruzi: a review

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