Plasmodium falciparum: analysis of karyotype polymorphism using chromosome-specific probes.

Chromosome size variation in Plasmodium falciparum has been examined using a double heterogenous pulse field gradient electrophoresis apparatus and a series of chromosome-specific probes. In the 11 different isolates analyzed the chromosomal markers always hybridized to the corresponding chromosome, indicating that translocations do not significantly contribute to chromosome size variations. Furthermore, despite probes specific for chromosomes 5 and 6 no evidence was obtained to support the hypothesis of a chromosome duplication involving these chromosomes. The double heterogenous electric field combined with longer pulse times allowed the genome to be resolved into a larger number of chromosomal bands and as a result permitted the more precise mapping of cloned genes.