Attempts to detect by physicochemical methods plasmid DNA in mycoplasmas of human origin before and after transformation to tetracycline resistance.
Physicochemical methods have been used to compare mycoplasma DNA capable of the genetic transformation of tetracycline resistance with DNA from tetracycline-sensitive mycoplasmas and their transformants. These mycoplasmas were isolated from human patients. The DNA extracted from Mycoplasma hominis tetr resistant to 100 microgram/mL tetracycline transforms tetracycline resistance to sensitive strains of Mycoplasma salivarium tets and Mycoplasma hominis tets but not Mycoplasma fermentans tets. Bulk DNA and DNA extracted by methods which increase the yield of circular DNA moieties were analyzed by cesium chloride and cesium chloride--ethidium bromide buoyant density ultracentrifugation and by horizontal and vertical agarose gel electrophoresis. Extrachromosomal DNA was not detected, which suggests that transformation was mediated by the recombination of chromosomal genes for tetracycline resistance and not by R factors. Moreover, no significant differences were detected in the DNA from the resistant and sensitive species or from their transformants and Mycoplasma fermentans tets which could not be transformed to resistance to 10 micrograms tetracycline/mL medium.
D002499:Centrifugation, Density Gradient; D004269:DNA, Bacterial / Q000032:analysis*; D004352:Drug Resistance, Microbial; D004587:Electrophoresis, Agar Gel; D006801:Humans; D009174:Mycoplasma / Q000187:drug effects / Q000235:genetics*; D011815:R Factors; D013752:Tetracycline / Q000494:pharmacology*
D004269:DNA, Bacterial; D013752:Tetracycline