In vivo conformation and replication intermediates of circular mitochondrial plasmids in Neurospora and Cryphonectria parasitica

► Mitochondrial plasmids have been examined by 2D agarose gel electrophoresis. ► DNA polymerase encoding circular plasmids replicate via rolling circles. ► Circular retroplasmids appear to have an RNA/DNA hybrid replication intermediate. ► Retroplasmids also appear to replicate via rolling circle intermediates. ► Plasmid-like elements have topologies suggestive of rolling circles.