Furness G, Cerone A M
J Infect Dis. 1979 Apr;139(4):444-51. doi: 10.1093/infdis/139.4.444.
DNA extracted from Mycomplasma hominis (Sprott strain), resistant to 100 micrograms of tetracycline/ml transformed M. hominis strain H29 and Mycoplasma salivarium strain S9, which are sensitive to 2.5 and 5.0 micrograms of tetracycline/ml, respectively, to resistance. The transformants were selected on agar medium containing 10 micrograms of tetracycline/ml. Some transformants were resistant also to 20 micrograms of tetracycline/ml, a finding confirming that transformation occurred between homologous and heterologous species and that resistance is stepwise and controlled by several genetic loci. Medium containing 10 micrograms of tetracycline/ml was bacteriostatic. Prototype experiments employing mixtures of strains that were tetr and tets (tetracycline-resistant and tetracycline-sensitive, respectively) demonstrated that tetr mutants and transformants formed typical fried-egg colonies when mixtures containing not more than 10(9) mycoplasmas were spread on tetracycline agar plates. No mutants to tetracycline resistance were detected. Both M. hominis and M. salivarium were competent after treatment with MgCl2 and CaCl2, while Mycoplasma orale type 2 was inactivated. During DNA extraction different quantities of DNA formed insoluble precipitates with protein, thus preventing quantitative experiments.
从对每毫升100微克四环素具有抗性的人型支原体（斯普罗特菌株）中提取的DNA，将对每毫升2.5微克和5.0微克四环素敏感的人型支原体H29菌株和唾液支原体S9菌株转化为具有抗性。在含有每毫升10微克四环素的琼脂培养基上选择转化体。一些转化体对每毫升20微克四环素也具有抗性，这一发现证实了同源和异源物种之间发生了转化，并且抗性是逐步的且由多个基因位点控制。含有每毫升10微克四环素的培养基具有抑菌作用。使用四环素抗性和四环素敏感（分别为tetr和tets）菌株混合物的原型实验表明，当含有不超过10⁹支支原体的混合物铺在四环素琼脂平板上时，tetr突变体和转化体形成典型的煎蛋菌落。未检测到对四环素产生抗性的突变体。用人型支原体和唾液支原体经氯化镁和氯化钙处理后具有感受态，而2型口腔支原体则被灭活。在DNA提取过程中，不同量的DNA与蛋白质形成不溶性沉淀，从而妨碍了定量实验。
