Plasticity of the histone H2A genes in a Brazilian and six Colombian strains of Trypanosoma cruzi

The analysis of three recombinant clones containing the histone H2A locus isolated from a genomic library of Trypanosoma cruzi DNA shows that the H2A gene loci are formed by 1.2 and 0.76 kb long intercalated units organized in a head-to-tail tandem array. The difference in length between the two gene units is due to the presence of a short interspersed nucleotide element (SINE)-like DNA sequence inserted at the 3′ end of some of these units. Southern, northern and chromosomal blot analysis of a Brazilian Y strain and six Colombian strains demonstrated the existence of polymorphisms regarding the relative copy number of the H2A gene units, the relative abundance of the H2A transcripts and their chromosomal location. These results show the existence of a dynamic organization in the H2A loci among T. cruzi strains in which a SINE-like sequence may be involved and support the fact that T. cruzi has a high degree of plasticity in its genome.