SPECIFIC A-RICH REPETITIVE DNA-SEQUENCES IN MAXICIRCLES FROM WILDTYPELEISHMANIA-MEXICANA AMAZONENSIS AND VARIANTS WITH DNA AMPLIFICATION(T)

To explain the low cross-hybridization between kinetoplast DNA maxicir cles of Leishmania parasites that show DNA amplification and those of parasites without DNA amplification, we isolated and cloned two maxici rcle fragments, one specific to each group of parasites. The cloned fr agment from wildtype L. m. amazonensis (MbpW94) and that from an arsen ite-resistant variant with DNA amplification (MpbA29) hybridized only to maxicircles from parasites of the group from which the fragment was originally derived. Both fragments were A+T-rich, tandemly repeated, and lacked long conserved open reading frames and transcriptional prod ucts. MpbW94 (685 bp) was harbored in a segment of roughly 12 kb in ma xicircles of wildtype parasites and of an arsenite-resistant variant w ithout DNA amplification, while MbpA29 (1121 bp) occupied a 6- to 7-kb segment of maxicircle DNA in arsenite- and tunicamycin-resistant vari ants with DNA amplification. These maxicircle DNA segments appear to r esemble previously described maxicircle divergent regions of other kin etoplastids. The presence of these specific sequences allows different iation between maxicircles of drug-resistant L. m. amazonensis with DN A amplification and those of parasites without DNA amplification and h elps explain the low cross-hybridization between maxicircles of the tw o parasite groups. Furthermore, these sequences allow the study of the kinetics of the changeover of A+T-rich regions of maxicircles during the transition period from one maxicircle type to the other. (C) 1994 Academic Press, Inc.