March 7, 2022

Yasu Xu is a doctoral candidate in biophysics from Wuhan, China. Xu studied material physics at the School of Physics and Technology, Wuhan, as an undergraduate and now studies synthetic biology. 

What is your area of research and why is it important?

Synthetic biology. We are trying to use existing biological components to create a genetic circuit that mimics the function like our daily use toggle switch which has two distinct states. Moreover, we can control the states and use it to turn on/off certain genes upon receiving a signal or as a sensor for other small molecules in the environment.

What are the larger implications of this research?

It would be the first CRISPRi/dCas12a base genetic toggle switch, which is programmable and compact comparing to the very first biological toggle switch.

You will be presenting your research, “Factors That Affect the Bistability of Programmable CRISPR-based Toggle Switches in Escherichia Coli,” at the American Physical Society’s March Meeting 2022. Can you tell us about this research?

Genetic toggle switches (TSs), as one of most basic genetic circuits, is the building block for complex circuits. However, the classic version is lack of orthogonality and programmability. This work aims to provide a systematical workflow that simulates, assembles, and characterizes TSs from thousands of potential constructs. We first developed a thermodynamic model to investigate different parameters that affect the bistability of any TS. Next, a versatile X-Seq assay is used to investigate each of these parameters by analyzing many potential constructs in parallel. We found that by carefully matching promoter strength and the copy number of toggle switch constructs, we can achieve bistability.

What are the broader implications of this research?

On the one hand, this research provides an efficient workflow to generate orthogonal TSs that can function in parallel to create more advanced genetic circuits that increase the layer of complexity of a genetic network. On the other hand, it enables researchers to program TS for different purposes, which has many practical applications in various fields. For example, it can be used to report the existence or concentration of some harmful molecules/content from environment.

What are your hobbies or interests outside of your research or scholarship?

I like experimenting different ways of brewing my own coffee or making espresso, and with music on.

Why did you choose Cornell to pursue your degree?

I was interested in the rotation system in the biophysics program. It allowed me to try three research projects in different labs in my first academic year, which let me find my perfect fit in Prof. Lambert’s lab and prepared me better for the transition from material physics to synthetic biology. Moreover, the view of Ithaca campus is really impressive, both architecturally and naturally.