Analysis of Plasmodium falciparum mitochondrial six-kilobase DNA by pulse-field electrophoresis

The 6-kb mtDNA of Plasmodium falciparum is thought to replicate by a recomb ination-dependent mechanism generating large complex branched structures. F or technical reasons, including shearing caused by DNA extraction methods, a meaningful quantitative comparison of large complex mtDNA forms has not b een feasible. With the use of pulse-held gel electrophoresis, which minimiz es any loss or shearing of DNA, we were able to identify an unusually slow migrating population of mtDNA that was resolved from the 6-23-kb population of linear concatemers. Levels of this slow-migrating population of mtDNA w ere highest during early schizont stage, suggesting that these forms repres ent replication intermediates. This approach provides a convenient means to monitor the presence of large mtDNA structures in P. falciparum.