HER FINALIST PROJECT: Building a long telescope in a short tube

WHAT LED TO THE PROJECT: Like many precocious kids, Mary-Dell Chilton felt drawn to astronomy; in the mid-1950's she joined a rakish amateur telescope-making group at the Adler Planetarium in Chicago. "It was the first place I was really with a bunch of scientists who spoke my language," she says.

In 1955, as a high school junior, she decided to raise her ambitions. Rather than settle for a telescope with a short tube, which allowed for lots of light collection, but not much amplification, or a long tube, which allowed for much amplification but not as much light, she constructed two mirrors that could focus light rays and, in effect, "have a long telescope in a compact tube."

Or at least she tried to construct two mirrors. Shaping the hyperbolic, convex curve of the secondary mirror proved troublesome. Even without achieving a perfect finished form for the instrument, though, she decided to write up her project for the 1956 Westinghouse Science Talent Search. Her report revealed she understood the physics, and she was selected as a finalist.

Chilton promptly set up her telescope in one corner of a hotel ballroom in Washington and focused in on a postage stamp she'd placed on a lightbulb on the far other end of the space. The experience "raised my aspirations—it gave me the idea that maybe I had some uncommon talent," she says.

THE EFFECT ON HER CAREER: Chilton's telescope-making career was short-lived. As a freshman at the University of Illinois at Urbana-Champaign, she tried to enroll in an astronomy course but was told to wait for her sophomore year. "As a young female student, I had a hard time being taken seriously in those days," she says. Rebuffed by astronomy, she said, "The hell with that," and "never went back." She majored in physics but fell asleep in lectures and so switched to chemistry to finish her undergraduate degree.

It wasn't until graduate school that she discovered her life's work—the new (and hence less rule-bound) field, emerging in the wake of James Watson and Francis Crick's discovery of DNA, called molecular biology. The double helix fascinated Chilton, though the practical applications weren't immediately clear. After doing her doctoral thesis on bacterial transformation and accepting a postdoctoral position at the University of Washington (U.W.) in Seattle, Chilton remembers wondering "Will I ever get a job? This is a pretty arcane skill."

Indeed, after her postdoc, because she was married to a professor in the chemistry department, she took a temporary job in U.W.'s microbiology department rather than trying to rise through the ranks somewhere else. "I thought to myself, at least I have the advantage of being a woman," she says. "My husband is the breadwinner, so I can just do what is interesting. I don't have to have a high-paying job."

Focusing on what interested her, though, turned out to be a brilliant move. In the 1970's, as Chilton and her husband Scott were raising two boys, a student in her microbiology class presented a paper on Agrobacterium and DNA hybridization—basically, the idea that this strain of bacterium's DNA might be combining with the DNA of the plants it attacked. The paper struck Chilton as wrong. But she started investigating the topic in earnest with several others at the U.W., and together, they eventually showed that Agrobacterium could plug its DNA into its host plant.

At this point, in 1979 Chilton accepted a "real" faculty position at Washington University in St. Louis. There, she and her postdocs (some funded by the Monsanto Corporation) showed that the disease-causing genes in Agrobacterium tumifaciens could be removed without affecting the microorganism's ability to insert DNA into plant cells. This paved the way for using Agrobacterium as a means of DNA transfer, and for genetic modification of plants in general. "We learned a lot from this little bacterium," she says. "It still has more to teach us."

WHAT SHE'S DOING NOW: In 1983 Chilton decided to leave academia and moved to the Research Triangle Park in North Carolina to work for what later became the Syngenta Corporation. Today, as Monsanto sells Roundup Ready soybeans and scientists look at genetic modifications that might make poplars and other sources of biomass into better ethanol stock, it's clear that Chilton's work revolutionized plant science. Although genetic modification is sometimes controversial, "the fact that it's possible scientifically and technically is amazing," says Philip Hammer, vice president of Philadelphia's Franklin Institute, which awarded Chilton the Franklin Institute Award in Life Science in 2002. "What she did is incredibly important in our understanding of genetics and relationships between bacteria and plants and bacteria and other organisms."

After managing teams for many years, she now has been "put out to pasture," she says. "I don't work on company projects." Instead, just as she did as a girl with her telescopes, and as a young mother in the lab, "I work on what amuses me." Currently, this is gene targeting—telling the DNA where to go in the plant genome. No one knows if any useful technology will be developed from this idea, but Chilton is still having such fun that she has no plans to retire. "Not as long as I can get up and go to the lab," she says.