title: Bacteriophage lambda derivatives carrying two copies of the cohesive end site.
mesh_terms: D002499:Centrifugation, Density Gradient; D002874:Chromosome Mapping; D002875:Chromosomes; D003090:Coliphages; D004261:DNA Replication; D004277:DNA, Single-Stranded; D004279:DNA, Viral / Q000032:analysis; D004926:Escherichia coli; D008854:Microscopy, Electron; D011995:Recombination, Genetic
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral