PT  - JOURNAL ARTICLE
AU  - Friedland, Ari E.
AU  - Lu, Timothy K.
AU  - Wang, Xiao
AU  - Shi, David
AU  - Church, George
AU  - Collins, James J.
TI  - Synthetic Gene Networks That Count
AID  - 10.1126/science.1172005
DP  - 2009 May 29
TA  - Science
PG  - 1199--1202
VI  - 324
IP  - 5931
4099  - http://science.sciencemag.org/content/324/5931/1199.short
4100  - http://science.sciencemag.org/content/324/5931/1199.full
SO  - Science2009 May 29; 324
AB  - Synthetic gene networks can be constructed to emulate digital circuits and devices, giving one the ability to program and design cells with some of the principles of modern computing, such as counting. A cellular counter would enable complex synthetic programming and a variety of biotechnology applications. Here, we report two complementary synthetic genetic counters in Escherichia coli that can count up to three induction events: the first, a riboregulated transcriptional cascade, and the second, a recombinase-based cascade of memory units. These modular devices permit counting of varied user-defined inputs over a range of frequencies and can be expanded to count higher numbers.