Characterisation of a simple, highly repetitive DNA sequence from the parasite Leishmania donovani

Repetitive DNA sequences of the Leishmania donovani genome have been identified by screening a recombinant DNA library made by cloning sheared genomic DNA into the vector pAT153. Bacterial clones containing a highly repetitive DNA sequence have been isolated. DNA sequencing has shown that this sequence is composed of tandem repeats of the sequence 5'-CCCTAA-3'. This sequence is identical to the telomeric repeats found in Trypanosoma brucei and hybridizes to all Leishmania chromosomes. In this study we show that there is considerable heterogeneity in the distribution and copy number of this repeat and associated hybridising sequences throughout the genomes of different Leishmania species.