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 sequence of #Trypanosoma cruzi$ was analyzed among 23 #T. cruzi$ stocks giving a reliable picture of the whole phylogenetic variability of the species. The profiles observed with the enzymes Hinf1 and Hae3 were linked together and supported the existence of two groups. Group 1 shows a 195 bp repeated unit (Hinf 1) and high molecular weight DNA (Hae 3), while group 2 presents a ladder profile for each enzyme, which is a characteristic of tandemly repeated DNA. The two groups, respectively, clustered stocks pertaining to the two principal lineages evidenced by izoenzyme and RAPD markers. The congruence among these three independent genomic markers corroborates the existence of two real phylogenetic lineages in #T. cruzi$. The specific monomorphic profiles for each major phylogenetic lineage suggest the existence of ancient sexuality and cryptic biological speciation. (Résumé d'auteur)