Franklin T J, Rownd R
J Bacteriol. 1973 Jul;115(1):235-42. doi: 10.1128/jb.115.1.235-242.1973.
The expression of R-factor-mediated resistance to tetracycline has been compared in Proteus mirabilis and Escherichia coli. Resistance to a range of concentrations of tetracycline was significantly lower in P. mirabilis than in E. coli in both induced and repressed states. Indirect evidence showed that conditions which result in a marked increase in the level of resistance of P. mirabilis harboring the R factor NR1 to chloramphenicol, streptomycin, and spectinomycin due to an amplification in the number of copies of r-determinants per cell do not detectably increase the level of resistance to tetracycline. Tetracycline resistance was inducible in early stationary-phase P. mirabilis NR1 although not after 5 h in this state. Double isotope labeling of control and tetracycline-induced P. mirabilis NR1 in early stationary phase revealed isotopic enrichment of certain peaks in extracts from induced cells subjected to polyacrylamide gel electrophoresis.
已对奇异变形杆菌和大肠杆菌中R因子介导的四环素抗性表达进行了比较。在诱导和抑制状态下，奇异变形杆菌对一系列四环素浓度的抗性均显著低于大肠杆菌。间接证据表明，由于每个细胞中r决定簇拷贝数的增加，导致携带R因子NR1的奇异变形杆菌对氯霉素、链霉素和壮观霉素的抗性水平显著提高的条件，并未显著提高对四环素的抗性水平。四环素抗性在奇异变形杆菌NR1的早期稳定期是可诱导的，尽管在此状态5小时后不可诱导。对处于早期稳定期的对照和四环素诱导的奇异变形杆菌NR1进行双同位素标记，结果显示，在聚丙烯酰胺凝胶电泳后的诱导细胞提取物中，某些峰出现了同位素富集。
