The volumes and transcript counts of single cells reveal concentration homeostasis and capture biological noise.
Bottom Line: Cell-to-cell variability is best captured in terms of concentration rather than molecule counts, because reaction rates depend on concentrations.We compared three cell clones that differ only in the genomic integration site of an identical constitutively expressed reporter gene.This study highlights the importance of the quantitative measurement of transcript concentrations in studies of cell-to-cell variability in biology.
Affiliation: Synthetic Systems Biology and Nuclear Organization Group, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands.Show MeSH
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Mentions: Early studies on stochastic gene expression relied on fluorescent proteins to assess protein noise by either taking snapshots (Elowitz et al., 2002; Ozbudak et al., 2002) or by using real-time fluorescence imaging (Rosenfeld et al., 2005; Sigal et al., 2006). More recently, single-molecule mRNA counting has been introduced as a method for absolute quantification of mRNA number (Golding et al., 2005; Raj et al., 2006, 2008). The advantage of single-transcript counting with single-molecule RNA fluorescence in situ hybridization (smFISH) is that it does not require genetic engineering (Raj et al., 2006, 2008; Zenklusen et al., 2008; Youk et al., 2010). Specific DNA probes tagged with fluorescent dyes are used to visualize individual mRNA molecules within fixed cells (Figure 1A).
Affiliation: Synthetic Systems Biology and Nuclear Organization Group, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH Amsterdam, The Netherlands.