Restriction fragment length polymorphism of 195 bp repeated satellite DNA of Trypanosoma cruzi supports the existence of two phylogenetic groups

The restriction fragment length polymorphism of the 195 bp repeated DNA seq uence of Trypanosoma cruzi was analyzed among 23 T. cruzi stocks giving a r eliable picture of the whole phylogenetic variability of the species. The p rofiles observed with the enzymes Hinf I and Hae III were linked together a nd supported the existence of two groups. Group 1 shows a 195 bp repeated u nit (Hinf I) and high molecular weight DNA (Hae III), while group 2 present s a ladder profile for each enzyme, which is a characteristic of tandemly r epeated DNA. The two groups, respectively, clustered stocks pertaining to t he two principal lineages evidenced by isoenzyme and RAPD markers. The cong ruence among these three independent genomic markers corroborates the exist ence of two real phylogenetic lineages in T. cruzi. The specific monomorphi c profiles for each major phylogenetic lineage suggest the existence of anc ient sexuality and cryptic biological speciation.