Trypanosoma cruzi exhibits inter- and intra-strain heterogeneity in molecular karyotype and chromosomal gene location.

Molecular karyotypes of 6 strains and 6 clones of Trypanosoma cruzi were determined using orthogonal-field-alternation gel electrophoresis. At least 15 different chromosome-sized DNA molecules, ranging in size from less than 200 kilobase pairs to greater than 2000 kilobase pairs, were resolved for each of the isolates examined. Many of the bands were present in different relative intensities suggesting that the number of individual chromosomes per organism may be considerably higher. Significant inter- and intra-strain differences in molecular karyotype and in the chromosomal locations of the genes for the spliced leader, tubulins, 5S ribosomal RNA and a heat shock protein were found. These marked chromosomal differences among T. cruzi strains and clones may be related to the high degree of phenotypic heterogeneity previously found in this parasite.