The protozoon Trypanosoma cruzi has a complex multiclonal
structure [1]. An outstanding feature of this parasite is that
its chromatin does not condense into mitotic chromosomes
during cell division [2]. Thus, the T. cruzi karyotype can be
analyzed by pulsed field gel electrophoresis (PFGE) but not
by classical cytogenetic techniques. Analysis of the molecular
karyotype in different strains and clones of T. cruzi using that
technique shows differences of up to 50% in the size of genetically
equivalent chromosomes [3], a fact suggesting the occurrence
of major chromosomal rearrangements during the
evolution of this parasite. It has also been proposed that T.
cruzi undergoes clonal-type propagation by cell proliferation
with rare events of genetic recombination [4].