iGEM is a stage for synthetic biology researchers to build a different world. Our team was inspired by previous iGEM teams and their projects. This year, we are eager to participate and contribute more.

At the beginning, we learned about previous projects from the websites, and we realized that, when dealing with real-world problems, issues like gene regulation, expression efficiency and system robustness are all important. When creating a great functional prototype, one should pay attention to all the details. And some of the new comers to synthetic biology may find it difficult to deal with. So we put it in our way: why not provide some validated gene expression regulation kits to iGEMers so that they no longer need to worry about building circuit, but focus on the key problem.

We came up with different versions of gene expression circuits: lambda bacteriophage, kinases reaction pathway, ribo-switch, RNAi and so on. We made efforts on the circuit construction and valid characterization data while users mainly focus on the input and output which are highly concerned with real-world problems. In this manner, our kit can serve as a useful tool to save their time and energy. On the whole, our theme is to offer bricks to help others build their own project.

And this summer we stepped a little forward to our goals. We worked out two versions of gene expression switch: a prokaryote tri-stable version derived from bacteriophage lambda and eukaryote bi-stable version based on ABA-response pathway.

In the tri-stable gene expression switch, users should define two input and related output gene signals. The logic gate below can illustrate the circuit better:

The circuit can rapidly reach its stable state because of positive feedback. And users can adjust its threshold too.

For more application examples:

We provided a solution to lactose intolerance based on this toolkit.

The input of signals are achieved by two promoters: plac (lactose inducible) and patp2 (base inducible). As for the output, we set the gene 1 as iLDH and gene 2 as beta-galactosidase. iLDH can transform lactic acid into pyruvate whileβ-galactosidase can degrade lactose. In this way, the system can provide a promising way for the treatment of lactose intolerance.

In our bi-stable switch, users can define an open signal and off signal to control the expression of target gene. The most attractive feature of the circuit is its switch efficiency, the mechanism of which is cascade reaction.