Applications

The idea of a counting device became quite popular since the beginning of synthetic biology.
In 2007, Drew Endy already mentioned in his speech of "The Implications of Synthetic Biology" http://mitworld.mit.edu/video/363
the great impact such a counting device would have for several fields (Min 24-26)

Not last this is due to the enormous possible applications.
Hereafter only a few of the major potential uses are listed:

Age determination in cell culture

The first application that came up to our minds was the one of the determination of the maturation state of cells. Currently the method of choice to indicate the aging of -for example- yeast cells is to count the number of scars that occur after cell division. Those can be labeled by Calcufluor and then be counted under the microscope. As this application can not be easily automated it is long lasting and expensive.

To determine the exact age of particular cells in a culture and the potential to sort cell populations of specific age immediately reveal applications. It would also be possible to observe transfection stability, gene expression or RNAi efficacy over several generations

Detection of abnormal growth

This application is closely related to the "age determination" above. If one would introduce such a system into -for example -cancer cell lines it would easily be possible to visualize different proliferation states during its development. Thus one would get deeper insights into cancer evolution and in understanding its mechanisms.

Basic property in electrical engineering

A more synthetic biological approach would be to use the system as base for programmes that require consecutive altering gene expression over multiple cell generations. Such a counter would serve as a basic and useful BioBrick in Synthetic Biology

Coupling to cell specific expression patterns

One could also think -as another major application - of replacing the XFPs with specific gene products such as insulin. Though this would allow to introduce an inducible cell cycle dependend expression pattern which could be precisly be timed. Following the idea of adding further bits one could even go on and think of more complex expression systems with antagonists and agonists.