title: Physical studies of a plasmid mediating tetracycline resistance and hydrogen sulfide production in Escherichia coli.
abstract: Tetracycline resistance and hydrogen sulfide production have been previously found to be plasmid-mediated in a naturally-occurring strain of Escherichia coli; both functions are specified by a single conjugative plasmid called pIP231(Te-H2S); pIP231DNA was isolated as covalently closed molecules in dye-buoyant density gradients. The base ratio of the DNA was found to be 50% GC by density gradient analysis. Electron micrographs of plasmid molecules showed a contour length of 20 +/- 2 mum (40 +/- 4 X 10(6) daltons). Between one and two copies of pIP231 molecules per host chromosome were found in E. coli K12.
mesh_terms: D001483:Base Sequence; D002499:Centrifugation, Density Gradient; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000032:analysis*; D004352:Drug Resistance, Microbial; D004926:Escherichia coli; D005111:Extrachromosomal Inheritance; D006862:Hydrogen Sulfide / Q000378:metabolism*; D008970:Molecular Weight; D010957:Plasmids; D013752:Tetracycline / Q000494:pharmacology*
chemical_list: D004269:DNA, Bacterial; D013752:Tetracycline; D006862:Hydrogen Sulfide