How do Zebrafish get their stripes? Why do we have only 5 digits on each hand?

Here's one possible answer: Turing Pattern.

Turing Pattern is a type of spatial pattern suggested by the British mathematician Alan Turing . He proposed that these patterns could be created by the network of two chemicals which have different diffusion rate. These two molecules are called the activator and inhibitor.

Because of its simplicity, the theory has attracted scientists in many fields, and thus various research has been carried out in the last 60 years. However, it was not easy to prove directly if those patterns are produced by the reaction-diffusion systems or another mechanism because living systems are so complex.

We therefore reconstructed a Turing system using two advantages of synthetic biology; simplicity and controllability. We designed a controllable system for pattern formation by creating spacial differences of E. coli concentrations by controlling their growth rate. This project leads to further understanding of Turing Pattern, especially characteristics of Turing Pattern generate by genetic circuits. It points the way to understanding of development of living things, and can be applied to tissue regeneration.

Now, the new door of synthetic biology has opened and awaits you to come in!