Comparative Restriction Enzyme Cleavage Analysis of Kinetoplast DNA from the Lower Trypanosomatids Isolated in the North-West Region of the USSR

Abstract

Summary The usefulness of molecular parameters of kinetoplast DNA (kDNA) as taxonomic criteria in the systematics of lower trypanosomatids was studied. 18 previously isolated lower trypanosomatid strains were classified on the basis of their minicircle DNA size and the maxicircle and minicircle cleavage profiles generated with restriction endonucleases. The results of such a classification were compared with the taxonomic status of isolates previously determined with the aid of the traditional systematics criteria. On the basis of cleavage data the isolates were grouped into four distinctly different schizodemes. The first one (A) comprised two Blastocrithidia species, whereas in the second schizodeme (B) three Leptomonas species were contained, thus revealing a good correspondence at the generic level between the 2 types of criteria. The schizodeme D was composed of a single Leptomonas species, which previously was found to differ significantly from the above mentioned three Leptomonas species by the traditional criteria. The most extensive schizodeme C included 12 isolates with a similar though not identical kDNA structure. Previously these isolates were referred to three different genera — Leptomonas, Crithidia and Blastocrithidia . The taxonomic status of several isolates has been determined presumptively. The extent of variability in kDNA structure within this schizodeme was not profound, being scarcely consistent with the different generic status of the isolates. To explain this discrepancy, the different possibilities including unspecific invasions were suggested. The results presented in this study clearly show that the restriction endonuclease analysis of kDNA may be employed as a useful and sensitive tool in developing the lower trypanosomatid taxonomy.