title: Formation of covalent circles of lambda DNA by E. coli extracts.
mesh_terms: D002499:Centrifugation, Density Gradient; D003090:Coliphages; D004279:DNA, Viral / Q000096:biosynthesis*; D004926:Escherichia coli / Q000378:metabolism*; D008854:Microscopy, Electron; D008967:Molecular Biology; D009154:Mutation
chemical_list: D004279:DNA, Viral