molecules per expression event 1.5±0.1 expression events per cell cycle 1.7±0.1
||Bacteria Escherichia coli
||Ullman G, Wallden M, Marklund EG, Mahmutovic A, Razinkov I, Elf J. High-throughput gene expression analysis at the level of single proteins using a microfluidic turbidostat and automated cell tracking. Philos Trans R Soc Lond B Biol Sci. 2012 Dec 24 368(1611):20120025. doi: 10.1098/rstb.2012.0025. p.5 right column bottom paragraphPubMed ID23267179
||P.2 left column top paragraph:"In this study, [investigators] report on a method combining microfluidics, single-molecule fluorescence microscopy and automated image analysis, enabling the study of the expression and super-resolution localization of low copy number transcription factors throughout thousands of bacterial lifespans per experiment. To illustrate the performance of the method, [they] quantify the dynamics of synthesis and intracellular localization of the lactose repressor by monitoring LacI–Venus expressed from its native promoter in live E. coli cells. [They] compare these observations with those obtained under identical conditions for cells expressing the reporter construct Tsr–Venus from the lactose permease gene, lacY, of the lactose operon."
||p.5 right column bottom paragraph:"Figure 5 shows lineage trees of cell histories stemming from a single ancestral root of strain SX701 (figure 5a) and JE116 (figure 5b) with bars corresponding to the number of Tsr–Venus and LacI–Venus molecules at the times they were synthesized. The trees are pruned as cells are lost from the segmentation and/or from the trap. For Tsr–Venus expressed from the lacY gene, [investigators] observe 1.5 ± 0.1 molecules per expression event and 1.7 ± 0.1 events per cell cycle. For LacI–Venus, 2.2 ± 0.05 molecules per expression event and 2.5 ± 0.04 events per cell cycle are observed. The average expression rates of Tsr–Venus and of LacI–Venus molecules over the cell cycle are shown in Figure 5c,d. Both show relatively large statistical errors, especially Tsr–Venus."