title: Covalently closed circular DNA molecules of low superhelix density as intermediate forms in plasmid replication.
mesh_terms: D002500:Centrifugation, Isopycnic; D004261:DNA Replication; D004269:DNA, Bacterial / Q000378:metabolism; D004270:DNA, Circular / Q000378:metabolism; D004926:Escherichia coli; D005111:Extrachromosomal Inheritance; D007700:Kinetics; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D010957:Plasmids
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular