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Science 324 (5931): 1156-1157

Copyright © 2009 by the American Association for the Advancement of Science

Cell Biology

It's the DNA That Counts

Christina D. Smolke

Natural biological systems have evolved genetic programs that control complex activities through the coordinated processing of signals received from their environments. The engineering of synthetic biological systems to perform programmed information processing and computational functions has remained a challenge. Counters represent one class of information-processing systems and can be used to trigger events in response to a series of detected signals that are integrated and processed over time. Engineered biological counters would enable many applications, such as regulating cell death after a specified number of cell division cycles, controlling cell differentiation in response to temporal cues, noninvasive monitoring of aging, and recording the frequency of environmental events. On page 1199 in this issue, Friedland et al. (1) report an important step toward the construction of genetically encoded counters.

Department of Bioengineering, Stanford University, Stanford, CA 94305, USA.

E-mail: csmolke{at}

Tuning and controlling gene expression noise in synthetic gene networks.
K. F. Murphy, R. M. Adams, X. Wang, G. Balazsi, and J. J. Collins (2010)
Nucleic Acids Res. 38, 2712-2726
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