relationship between mRNA and protein levels -- a lot of noise

Ugh, something to keep in mind for our small sample qRT-PCR projects:

For this week in Science:

Genetically identical cells in the same environment can show variation in gene expression that may cause phenotypic variation at the single-cell level. But how noisy are most genes?Taniguchi et al. (p. 533; see the Perspective by Tyagi) now report single-cell global profiling of both messenger RNA (mRNA) and proteins in Escherichia coli using a yellow fluorescent protein fusion library. As well as a common extrinsic noise in high-abundance proteins, large fluctuations were observed in low-abundance proteins. Remarkably, in single-cell experiments, mRNA and protein levels for the same gene were uncorrelated.

Title links to Tyagi perspective