title: The presence of repeated DNA sequences and a partial restriction map of the pSym of Rhizobium fredii USDA193.
abstract: The large, 350-kb Sym (symbiotic) plasmid pRjaUSDA193 of Rhizobium fredii was examined to determine the frequency of repeated sequences present and to produce a physical and genetic map of a large region of the plasmid. A novel hybridization method, the Southern Cross, revealed that the plasmid pRjaUSDA193 contained many repeated sequences and assisted in restriction enzyme mapping of a 100-kb region containing nod genes. A cosmid clone bank was prepared with the broad-host-range cosmid pVK102. The restriction enzymes HindIII, HpaI, and KpnI were used to construct a physical map of overlapping clones. Labeled nod gene sequences were used to determine their location in the mapped region.
mesh_terms: D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004262:DNA Restriction Enzymes; D005798:Genes, Bacterial; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012091:Repetitive Sequences, Nucleic Acid; D012231:Rhizobium / Q000235:genetics*
chemical_list: D004262:DNA Restriction Enzymes