Minisatellite-like repeat sequences in the genome of rodent malaria parasites.

Abstract

Using minisatellite DNA probes and various Southern blots containing DNA samples from rodent malaria parasites it was shown that minisatellite-like sequences occur in the genome of these Plasmodium species. In contrast to the high copy number as observed in higher eukaryotes, the use of fingerprinting techniques on DNA from these parasites reveals that minisatellite sequences are only present at a small number of loci. When parasite lines which differ in biological parameters are compared, no frequent restriction fragment length polymorphism (RFLP) is observed. Screening data banks revealed the presence of repeated copies of one of the probes, which has the monomer sequence CAGGTGG, in the DNA encoding the immunodominant peptide repeat region of the circumsporozoite (CS) protein from a Plasmodium cynomolgi strain. Comparing the sequences for the CS protein from a number of strains of P. cynomolgi revealed that the core region of the repeats, though subject to limited variation, shares homology to the bacterial recombination signal sequence Chi (GCTGGTGG). The implications of the above findings for genetic variation in malaria parasites and evolution of minisatellite sequences will be discussed.