Tolker-Nielsen T, Holmstrøm K, Boe L, Molin S
Department of Microbiology, Technical University of Denmark, Lyngby.
Mol Microbiol. 1998 Mar;27(6):1099-105. doi: 10.1046/j.1365-2958.1998.00760.x.
Expression of a lac operon in Salmonella typhimurium single cells was monitored using lac mRNA targeting in situ reverse transcription-polymerase chain reaction (RT-PCR). It is demonstrated that suboptimal induction of the lac operon in a culture of S. typhimuriuml/F'lac+ cells generates a subpopulation in which transcription of the lac operon occurs and another subpopulation in which transcription of the lac operon is repressed, whereas suboptimal induction of the lac operon in a culture of S. typhimuriuml/F'lacY cells generates a population with uniform levels of lac mRNA. The outcome of the single-cell lac mRNA detection assay was compared with the outcome of a single-cell beta-galactosidase assay. In cultures grown under different suboptimal lac induction conditions, the fraction of cells in which transcription of the lac operon occurred was concurrent with the fraction of cells showing beta-galactosidase activity. Besides supporting the hypothesis that the lactose permease has a role in generating non-genetic heterogeneity in suboptimally induced cultures of Lac+ cells, these results demonstrate the usefulness of in situ RT-PCR for the study of non-genetic population heterogeneities.
利用针对lac mRNA的原位逆转录-聚合酶链反应（RT-PCR）监测了鼠伤寒沙门氏菌单细胞中lac操纵子的表达。结果表明，在鼠伤寒沙门氏菌l/F'lac+细胞培养物中对lac操纵子进行次优诱导会产生一个亚群，其中lac操纵子发生转录，另一个亚群中lac操纵子的转录受到抑制，而在鼠伤寒沙门氏菌l/F'lacY细胞培养物中对lac操纵子进行次优诱导会产生一个lac mRNA水平均匀的群体。将单细胞lac mRNA检测试验的结果与单细胞β-半乳糖苷酶试验的结果进行了比较。在不同次优lac诱导条件下生长的培养物中，lac操纵子发生转录的细胞比例与显示β-半乳糖苷酶活性的细胞比例一致。这些结果除了支持乳糖通透酶在次优诱导的Lac+细胞培养物中产生非遗传异质性中起作用的假设外，还证明了原位RT-PCR在研究非遗传群体异质性方面的有用性。
