The sequences of 10 conservative regions (CR) of minicircles of 6 selected isolates of freshwater fish try-panosomes have typical organization of this region with high degree of sequence conservation. The comparison with CRs of other trypanosomatids showed that freshwater fish trypanosomes represent a compact separate group within the genus Trypanosoma. The alignment of all sequences obtained revealed, however, the existence of 2 types of CRs in sequenced minicirclcs, with the differences concentrated in a short region. Taxonomic consequences of these results arc discussed.
Phylogenetic relationships within the suborder Trypanosomatina were inferred from the kinetoplast DNA minicircle conserved region sequences. Trees built using distancc-matrix (Neighbor-Joining) and maximum parsimony methods showed that the minicircle conserved regions (CRs) provide a sensitive and specific molecular marker suitable for phylogenetic analyses of subspecies and strains of trypanosomalid flagellates, as testified by the subdivision of the genus Leishmania into the subgenera Leishmania, Viannia and Sauroleishmania. However, since Phytomonas and monogenetic parasites of insects represent the earliest diverging groups, the CRs do not seem to be useful for inference of relationships among major lineages of the order Kinetoplastida.