Summary

Counting is the action of finding the number of elements in a set. Past attempts at developing counters in cells have mostly attempted to mimic the binary methods that computers use to count.
Our first counter takes a new approach to counting in cells, essentially a mechanical rotary counter implemented on a micro scale. Each time the counter detects an input, it performs an excision and integration directly down-stream of the active site, turning on a reporter and rotating over one "notch" on the counter.
Our second counter operates on the wholly different principle that the statistical occurrence of a rare event in a large population can be modeled. Each cell in our population harbors a construct that when stimulated has a small chance of excising a terminator and expressing a reporter gene which creates cells with a distinctive phenotype. The number of these cells is thus an accurate count of the number of input stimuli.