“In five to six years, synthetic biology will be as big as electronics was in 1953,” predicted Dr. Stephen Davies, referring to the year modern electronics took a decided leap forwards.
Davies, a researcher in the institute of biomaterials and biomedical engineering (IBBME) researches genetic circuits. “Genetic circuits are analogous to electronic circuits,” said Davies. In electronic circuits, transistors control the flow of electronic current, like a tap controls the flow of water.
“Genetic circuits are composed of genes and the control regions of gene, the promoters. Promoters turn genes on and off. Proteins control the expression of promoters and thus control the genes that are expressed,” he explained.
Genetic circuits control the level of protein the cell produces. “Transistors turn current on and off in electronic circuits. They’re controlled by signals coming in to their input just like promoters are controlled by the signals proteins send them,” said Davies.
Davies’ work is one of many applications in the burgeoning branch of synthetic biology, a relatively new field of research, it combines biology and engineering to build new biological functions or modify existing ones.
For example, the idea behind “cellular doctors” relies on researchers loading a set of instructions onto a virus, the virus entering a cell, performing a series of measurements, making a decision based on the measurements, and fixing the problem. According to Davies, “cellular doctors” may become a reality in fifteen to twenty years.
Part of that is because our grasp of biology remains rather tenuous. “The individual components of a cell are well studied but as engineering devices, they are not understood well. The reaction parameter values are unknown. In chemistry, if you do X, you get Y and you know exactly how much Y you’re going to get. We want to do the same with synthetic biology. We want to make it predictable,” Davies said.
“By developing an understanding of a simple organism, we can move onto studying more complex organisms,” he said. Understanding the simple allows a model to be built and comparisons to be made between the model and the actual in a complex system. “By looking at what we do know, we can deduce what we don’t know.”
And scientists are still struggling to build the nuts and bolts of genetic circuits. A Nature paper in 2000 detailed the construction of a genetic toggle switch. Davies explained that “the genetic toggle switch works based on a simple analog function. Send an external signal, the input to the cell. This gives it a little burst and the cell may go into state ‘one.’ Give it another little burst and it goes into state ‘0.’” The external signal could also be the level of sugars in the environment or temperature, since biological systems usually have more than two states.
Six years on, researchers are starting to build simple contraptions. In early November, Davies traveled to the Intercollegiate Genetically Engineered Machine (iGEM) competition taking place at the Massachusetts Institute of Technology (MIT) with two undergraduate students, Hannah Fung and Emanuel Nazareth.
The group’s project involved constructing a “Cell-see-us” thermometer and a bacterial “etch-a-sketch.” Despite a team of undergraduate and graduate students working through the summer right until it was time to present, the projects didn’t quite work as expected. In fact, none of the projects the 13 teams presented worked as expected. U of T came away with the “Nothing Will Stop Us” award, and is preparing for next summer’s iGEM.
“I think synthetic biology is an interesting field because it’s interdisciplinary. It’s neat to combine molecular biology and electronics,” Nazareth commented.
