Xiling Shen uses engineering principles to understand biological systems and create new ones.
"I'm not a typical double E," he says. "My research is using engineering concepts and tools to help solve biological problems, especially in what is called systems biology and synthetic biology."
Systems biology uses high-throughput methods to quickly collect information on every chemical signal involved in a biological process. "Then the question is, 'How do you make sense of all that data?'" Shen says. "In electrical engineering, we have developed all kinds of tools and concepts to help us design and analyze complex systems."
Biological mechanisms can be thought of as well designed machines, says Shen. "If a gene or a bacterium is to do its work, it has to follow certain principles in a certain way, just like a chip," he says. "So if you use tools developed from a design perspective, combined with all the data collected from systems biology, you can get a deeper understanding of the underlying principles behind a biological process."
Once Shen thinks he has discovered how a biological mechanism works, he verifies his hypothesis with experiments.
Shen is using these techniques to study a kind of bacteria that is abundant in nutrient-poor lakes. "We are using this approach to understand how these species are going to respond to the environmental changes caused by global warming and what the impact of their response will be," he says. "They are very important for the carbon cycle." He is also extending the techniques to analyze more complex systems such as stem cells.
With a complete understanding of a system, Shen can then change it to perform desired functions. "Traditionally, if people wanted to modify a biological system, all they could do is tweak one or two parts and hope to hit the jackpot because they really didn't have a full understanding of it," he says. "The rationale was that it's such a complex system, it's really hard to do any rational design."
Simple bacteria could be modified to help convert cellulose to ethanol, or a protein could be modified to deliver a cancer drug more effectively. "The concept is really borrowed from electrical engineering, which is: we need reliable and characterizable parts and devices that would allow us to build more complex behavior out of those simple parts," says Shen. "You want to characterize every single gene and really understand how they behave in different environments so once you start assembling systems from the parts they actually behave the way you expect."
Complete understanding of biological systems can also lead to better instrumentation, says Shen. "If you really look at the problem across the chasm, there's a lot of global optimization that you can do if you combine the biology and electrical engineering," he says. "You can come up with much simpler solutions if you really understand the tradeoffs in both fields."
One of the things that drew Shen to Cornell is its collaborative culture. He is a member of three fields besides electrical engineering –biomedical engineering, biological and environmental engineering, and computational biology. "It actually helps me tremendously," he says. "At other schools, you can be affiliated with another department, but it's definitely not as easy as how they make it here at Cornell."