Faces of the Foundation: Sarah McFann

In the first four hours of a fruit fly’s life, a single fertilized cell goes through about 13 rounds of division, until the fly has grown to a football-shaped glob containing about 6000 different nuclei. Then, the dance begins.;

A genetic switch turns on here and there, another turns off here, and an ensemble of chemical signals come marching out from various points on the fly. They spread through the embryo in movements choreographed by physics, awaking and suppressing genes and proteins along their path, and interacting with other signals to form distinct segments of the fly. When the process is done, the fly’s shape is set — this end will be the head, that side the belly, and these patterned stripes will form the body segments.

The dance that sets the flies fate is so complicated that it’s only really been studied piece by piece, motion by motion — but Hertz Fellow Sarah McFann wants to study the complete score.

“I’m an engineer at heart,” says Sarah, but “working with life every day, seeing things grow and move around and live and die, makes me excited to come into work every morning.” She first combined these two passions during a summer research experience at UC Berkeley, building a microscope that worked with an iPad to watch cancer cells start acting normally again in the right conditions.

Now, McFann is in the second year of her PhD in Chemical and Biological Engineering at Princeton University – and says it’s the right time and place to be at the intersection of chemical and biological engineering. A growing base of knowledge about the genes and signaling pathways involved gives her the pieces of the puzzle. New lab tools like advanced microscopes and optogenetics (which allows scientists to flip on chemical signals in a cell with just a bit of laser light) let her let her precisely tweak the timing and pattern of signals within the embryo to see how different signaling events act together. And she credits her Hertz Fellowship for giving her the support she needed to take on as ambitious a project as building an accurate model of the entire system.

“We’re finally at the point where we can work through every piece of the puzzle,” she says.

Sarah is well-prepared to take on the challenge of combining experiments and computer modelling into a complete understanding, says Stanisalv Schvartsman, one of Sarah’s advisors. “She thinks very clearly and she’s fearless when it comes to trying and learning many different ideas and techniques,” he says.

Sarah splits her time between computer modelling, theoretical coursework, and messy lab experiments. She credits lunch breaks spent dancing ballet for keeping her focused on the dance of chemical signals. “Thinking about movement in those two different ways, there’s a really clear connection to me,” she says. “Dance can be used to explore those concepts in a really profound way that adds a deeper level of insight.” In fact, she hopes one day soon to choreograph a human dance that shows the connection, bringing the microscopic world of reaction, diffusion, and genetics to life in a way we all can feel and understand.