Electrophoretic profiles of mitochondrial plasmids in Neurospora suggest they replicate by a rolling circle mechanism.

Migratory behaviour of mitochondrial plasmids from Neurospora crassa Mauriceville-1c and N. intermediate LaBelle has been studied by pulsed field gel electrophoresis (PFGE). Electrophoretic profiles demonstrate that long, linear molecules of a heterogeneous size are the prevailing form of plasmid DNA in vivo. Circular forms represent less than 8-9% of plasmid DNA. Single stranded DNA regions are abundant and lead to electrophoretic inertia of a significant amount of plasmid DNA. These profiles indicate that both plasmids replicate by the recombination dependent rolling circle mechanism.