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Interclonal variations in the molecular karyotype of Trypanosoma cruzi: chromosome rearrangements in a single cell-derived clone of the G strain.

Lima FM, Souza RT, Santori FR, Santos MF, Cortez DR, Barros RM, Cano MI, Valadares HM, Macedo AM, Mortara RA, da Silveira JF - PLoS ONE (2013)

Bottom Line: Our results also suggest that telomeric regions are involved in this process.The variant represented by clone D11 could have been induced by the stress of the cloning procedure or could, as has been suggested for Leishmania infantum, have emerged from a multiclonal, mosaic parasite population submitted to frequent DNA amplification/deletion events, leading to a 'mosaic' structure with different individuals having differently sized versions of the same chromosomes.If this is the case, the variant represented by clone D11 would be better adapted to survive the stress induced by cloning, which includes intracellular development in the mammalian cell.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.

ABSTRACT
Trypanosoma cruzi comprises a pool of populations which are genetically diverse in terms of DNA content, growth and infectivity. Inter- and intra-strain karyotype heterogeneities have been reported, suggesting that chromosomal rearrangements occurred during the evolution of this parasite. Clone D11 is a single-cell-derived clone of the T. cruzi G strain selected by the minimal dilution method and by infecting Vero cells with metacyclic trypomastigotes. Here we report that the karyotype of clone D11 differs from that of the G strain in both number and size of chromosomal bands. Large chromosomal rearrangement was observed in the chromosomes carrying the tubulin loci. However, most of the chromosome length polymorphisms were of small amplitude, and the absence of one band in clone D11 in relation to its reference position in the G strain could be correlated to the presence of a novel band migrating above or below this position. Despite the presence of chromosomal polymorphism, large syntenic groups were conserved between the isolates. The appearance of new chromosomal bands in clone D11 could be explained by chromosome fusion followed by a chromosome break or interchromosomal exchange of large DNA segments. Our results also suggest that telomeric regions are involved in this process. The variant represented by clone D11 could have been induced by the stress of the cloning procedure or could, as has been suggested for Leishmania infantum, have emerged from a multiclonal, mosaic parasite population submitted to frequent DNA amplification/deletion events, leading to a 'mosaic' structure with different individuals having differently sized versions of the same chromosomes. If this is the case, the variant represented by clone D11 would be better adapted to survive the stress induced by cloning, which includes intracellular development in the mammalian cell. Karyotype polymorphism could be part of the T. cruzi arsenal for responding to environmental pressure.

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Possible mechanisms of genetic recombination that could give rise to chromosomal polymorphism in T.cruzi.Panel A) Translocation mechanism: a DNA fragment (210 kb) from a heterologous chromosome (red) is translocated to another chromosome (blue) by homologous recombination, generating “homologous” chromosomes of different sizes. Panel B) Fusion and breakage mechanism: two homologous chromosomes of different sizes are fused, forming a dicentric chromosome which is then broken, generating two chromosomes of similar sizes but with different gene content.
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pone-0063738-g007: Possible mechanisms of genetic recombination that could give rise to chromosomal polymorphism in T.cruzi.Panel A) Translocation mechanism: a DNA fragment (210 kb) from a heterologous chromosome (red) is translocated to another chromosome (blue) by homologous recombination, generating “homologous” chromosomes of different sizes. Panel B) Fusion and breakage mechanism: two homologous chromosomes of different sizes are fused, forming a dicentric chromosome which is then broken, generating two chromosomes of similar sizes but with different gene content.

Mentions: The other syntenic group (TcChr7) was assigned to one single chromosomal band in the G strain and two similar-sized bands in clone D11 that may correspond to size-polymorphic homologous chromosomes. A number of different mechanisms may be responsible for the chromosome size polymorphism. The hybridization of the same markers in two distinct bands in clone D11 leads us to speculate that repetitive sequences may have been amplified or that a chromosomal fragment of approximately 210 kb may have been translocated in one of the homologues, possibly by a similar mechanism to that suggested in Figure 7.


Interclonal variations in the molecular karyotype of Trypanosoma cruzi: chromosome rearrangements in a single cell-derived clone of the G strain.

Lima FM, Souza RT, Santori FR, Santos MF, Cortez DR, Barros RM, Cano MI, Valadares HM, Macedo AM, Mortara RA, da Silveira JF - PLoS ONE (2013)

Possible mechanisms of genetic recombination that could give rise to chromosomal polymorphism in T.cruzi.Panel A) Translocation mechanism: a DNA fragment (210 kb) from a heterologous chromosome (red) is translocated to another chromosome (blue) by homologous recombination, generating “homologous” chromosomes of different sizes. Panel B) Fusion and breakage mechanism: two homologous chromosomes of different sizes are fused, forming a dicentric chromosome which is then broken, generating two chromosomes of similar sizes but with different gene content.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646811&req=5

pone-0063738-g007: Possible mechanisms of genetic recombination that could give rise to chromosomal polymorphism in T.cruzi.Panel A) Translocation mechanism: a DNA fragment (210 kb) from a heterologous chromosome (red) is translocated to another chromosome (blue) by homologous recombination, generating “homologous” chromosomes of different sizes. Panel B) Fusion and breakage mechanism: two homologous chromosomes of different sizes are fused, forming a dicentric chromosome which is then broken, generating two chromosomes of similar sizes but with different gene content.
Mentions: The other syntenic group (TcChr7) was assigned to one single chromosomal band in the G strain and two similar-sized bands in clone D11 that may correspond to size-polymorphic homologous chromosomes. A number of different mechanisms may be responsible for the chromosome size polymorphism. The hybridization of the same markers in two distinct bands in clone D11 leads us to speculate that repetitive sequences may have been amplified or that a chromosomal fragment of approximately 210 kb may have been translocated in one of the homologues, possibly by a similar mechanism to that suggested in Figure 7.

Bottom Line: Our results also suggest that telomeric regions are involved in this process.The variant represented by clone D11 could have been induced by the stress of the cloning procedure or could, as has been suggested for Leishmania infantum, have emerged from a multiclonal, mosaic parasite population submitted to frequent DNA amplification/deletion events, leading to a 'mosaic' structure with different individuals having differently sized versions of the same chromosomes.If this is the case, the variant represented by clone D11 would be better adapted to survive the stress induced by cloning, which includes intracellular development in the mammalian cell.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.

ABSTRACT
Trypanosoma cruzi comprises a pool of populations which are genetically diverse in terms of DNA content, growth and infectivity. Inter- and intra-strain karyotype heterogeneities have been reported, suggesting that chromosomal rearrangements occurred during the evolution of this parasite. Clone D11 is a single-cell-derived clone of the T. cruzi G strain selected by the minimal dilution method and by infecting Vero cells with metacyclic trypomastigotes. Here we report that the karyotype of clone D11 differs from that of the G strain in both number and size of chromosomal bands. Large chromosomal rearrangement was observed in the chromosomes carrying the tubulin loci. However, most of the chromosome length polymorphisms were of small amplitude, and the absence of one band in clone D11 in relation to its reference position in the G strain could be correlated to the presence of a novel band migrating above or below this position. Despite the presence of chromosomal polymorphism, large syntenic groups were conserved between the isolates. The appearance of new chromosomal bands in clone D11 could be explained by chromosome fusion followed by a chromosome break or interchromosomal exchange of large DNA segments. Our results also suggest that telomeric regions are involved in this process. The variant represented by clone D11 could have been induced by the stress of the cloning procedure or could, as has been suggested for Leishmania infantum, have emerged from a multiclonal, mosaic parasite population submitted to frequent DNA amplification/deletion events, leading to a 'mosaic' structure with different individuals having differently sized versions of the same chromosomes. If this is the case, the variant represented by clone D11 would be better adapted to survive the stress induced by cloning, which includes intracellular development in the mammalian cell. Karyotype polymorphism could be part of the T. cruzi arsenal for responding to environmental pressure.

Show MeSH
Related in: MedlinePlus