RESUMEN
We have determined the nucleotide sequences of the minicircles representing a major (pLURkE3) and a minor (pLURkH13) class populations from the kinetoplast DNA of Leishmania strain UR6. These minicircles have sequence organization similar to other kinetoplastid parasites, however, they have some unique structural features. These features include the following: (i) imperfect inverted repeat in the variable regions, similar to the conserved sequence elements of guide RNA genes in African trypanosomes, (ii) tandem and non-tandem direct repeats of 8 bp or longer scattered throughout the minicircles, (iii) non uniform strand distribution of bases throughout the minicircles and (iv) high TG content, more than half of the molecules being extremely (T + G) versus (A + C) strand biased. The heterogeneity of minicircle sequences in the variable regions may be exploited in developing recombinant DNA based diagnostic probes for detection and classification of Leishmania species.