title: Recircularization and autonomous replication of a sheared R-factor DNA segment in Escherichia coli transformants.
abstract: Controlled shearing of R-factor DNA leads to formation of fragments carrying an antibiotic resistance gene present on, but not expressed by, the intact R-factor. Transformation of CaCl(2)-treated E. coli by such fragments yields an autonomously replicating tetracycline-resistance plasmid (Tc6-5) that contains only a small fraction of the genome of the parent R-factor, and lacks both its fertility functions and its other drug-resistance determinants. Although the Tc6-5 plasmid is not self-transmissible, it can interact and/or recombine with conjugally-proficient plasmids that promote its transfer to other bacteria.
mesh_terms: D001965:Bromides; D002122:Calcium Chloride / Q000494:pharmacology; D002499:Centrifugation, Density Gradient; D002586:Cesium; D002712:Chlorides; D003227:Conjugation, Genetic; D004261:DNA Replication; D004269:DNA, Bacterial; D004270:DNA, Circular / Q000302:isolation & purification; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects; D004996:Ethidium; D005111:Extrachromosomal Inheritance; D005796:Genes; D008854:Microscopy, Electron; D009154:Mutation; D009268:Nalidixic Acid / Q000494:pharmacology; D012475:Salmonella / Q000187:drug effects; D013752:Tetracycline / Q000494:pharmacology; D014170:Transformation, Genetic; D014461:Ultracentrifugation
chemical_list: D001965:Bromides; D002712:Chlorides; D004269:DNA, Bacterial; D004270:DNA, Circular; D002586:Cesium; D009268:Nalidixic Acid; D004996:Ethidium; D013752:Tetracycline; D002122:Calcium Chloride