title: Hybrid T4 r II B cistrons created by genetic duplications.
mesh_terms: D003090:Coliphages; D004926:Escherichia coli; D005796:Genes; D005827:Genetics, Microbial; D006579:Heterozygote; D006824:Hybridization, Genetic; D008967:Molecular Biology; D009154:Mutation; D011995:Recombination, Genetic