title: Superhelix density of replicating simian virus 40 DNA molecules.
mesh_terms: D001665:Binding Sites; D002499:Centrifugation, Density Gradient; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis / Q000302:isolation & purification; D004996:Ethidium; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D013539:Simian virus 40 / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D004279:DNA, Viral; D004996:Ethidium