Abstract

SUAREZ, Brian Alejandro; CUERVO, Claudia Liliana  and  PUERTA, Concepción Judith. The intergenic region of the histone h2a gene supports two major lineages of Trypanosoma rangeli. Biomédica [online]. 2007, vol.27, n.3, pp.410-418. ISSN 0120-4157.

Introduction. Trypanosoma rangeli has been classified in the KP1(+) and KP1(-) subpopulations, based on the mini-exon gene and kinetoplast DNA minicircle amplification profiles. Objective. The intergenic region of the histone h2a gene was compared between KP1(+) and KP1(-) strains of T. rangeli to substantiate this classification. Materials and methods. The amplification, cloning and sequencing of the h2a gene intergenic region was undertaken for the Tre and 5048 KP1(-) strains for comparison with the Choachí KP1(+) strain. These sequences, along with those previously reported for the KP1 (+) and KP1 (-) H14 and C23 strains, were used to reconstruct phylogenetic trees based on the "neighbor-joining", maximum parsimony and maximum likelihood methods. The Y strain of Trypanosoma cruzi was chosen as the outgroup. Results. Intra-specific heterogeneity was observed in the size of the gene region under study, supported by bootstarp values of 85% (neighbor-joining), 66% (maximum parsimony) and 57% (maximum likelihood). The KP1(-) strains were grouped apart, clearly differentiated from the KP1(+) strains. The latter demonstrated a higher intra-specific heterogeneity, both in sequence length and composition. In addition, a closer phylogenetic relationship between T. rangeli and T. cruzi was found to be more closely related to one another than to T. rangeli and Trypanosoma brucei. Conclusion. Phylogenetic analyses of analyzed strains based on the intergenic region of the h2a genes supported the T. rangeli grouping in two major subpopulations known as KP1(+) and KP1(-) strains. However, a higher number of strains are needed to confirm this finding.

Keywords : Trypanosoma [genetics]; DNA, intergenic; genes; histones [genetics]; conserved sequence; phylogeny.

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