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Sci. STKE, 19 December 2006
Vol. 2006, Issue 366, p. re17
[DOI: 10.1126/stke.3662006re17]


From Fluctuations to Phenotypes: The Physiology of Noise

Michael S. Samoilov1*, Gavin Price2*, and Adam P. Arkin1,2*

1Howard Hughes Medical Institute, Berkeley, CA 94720, USA.
2Howard Hughes Medical Institute, Department of Bioengineering, University of California at Berkeley, Center for Synthetic Biology, Virtual Institute of Microbial Stress and Survival, Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.

Gloss: Most biological organisms are continuously faced with high levels of complexity, noise, and unpredictability arising from the random movement of and interactions among individual molecules in a cell, the varied environmental conditions encountered by species populations in the wild, and other causes. Thus, they have adapted to survive and proliferate in highly variable, fluctuating, and probabilistically evolving ("stochastic") environments. Moreover, random molecular-scale mechanisms, such as those underlying genetic mutation, play key roles in population-scale processes, including evolution. The ubiquity of characteristically noisy dynamics at the scale of individual organisms, such as those observed during gene expression, has become more widely recognized in the past few years. What we now realize is that these stochastic fluctuations are not simply tolerated or counteracted, but actively contribute to cellular and organismal phenotypes. Indeed, noisy dynamics appear to be essential for many vital physiological processes in various organisms. In this STKE Review with two figures and 70 references, we discuss a multiscale framework for considering the role of stochastic and other molecular dynamics "deviant" from the classical continuous-deterministic model, including their contributions to the physiology of various biological processes (e.g., changes in gene expression) in the context of such diverse settings as fly eye development and bacterial competence response.

*Corresponding author. E-mail, mssamoilov{at}, gaprice{at}, aparkin{at}

Citation: M. S. Samoilov, G. Price, A. P. Arkin, From Fluctuations to Phenotypes: The Physiology of Noise. Sci. STKE 2006, re17 (2006).

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