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Celebrating 60 Years of the DNA Double Helix

By Lauren Ober


In nearly every class that Nate Harshman, chair of the Department of Physics, teaches he demonstrates the idea of X-ray diffraction by shooting a green laser at a series of plastic high-precision lithographic discs.

The laser bounces off the discs in a series of patterns meant to mimic the patterns DNA strands make when beamed with X-rays.  

The demonstration is a simple one, but speaks to a critical development in the study of DNA. Was it not for the British researcher Rosalind Franklin pioneering X-ray diffraction on DNA, the discovery of the DNA double helix by the famed duo James Watson and Francis Crick might not have happened when it did.

Franklin’s work, Harshman said, was as essential to the study of DNA as anything Watson and Crick did.

On April 25 — known as DNA Day, the date in 1953 when the famous DNA papers were first published — the American University community celebrates the work of Watson, Crick, and Franklin.

Through a series of events held on DNA Day, AU commemorates the trailblazing work of the DNA pioneers and looks to the future of genetic study both here on campus and out in the world.

One of the events scheduled is Harshman’s demonstration, "X-Ray the DNA! A Diffraction Distraction." His reasons for presenting this demo are two-fold — to explain a major development in the study of DNA and to give Franklin credit for her achievement.

"X-ray diffraction of DNA is a scientific success story," he said. "But when we celebrate Watson and Crick and don’t celebrate Rosalind Franklin, we’re really missing the story. This is a part of the story that’s not recognized."

Harshman isn’t the only professor presenting on DNA Day. Professor John Nolan from the Department of Mathematics and Statistics will give a brief talk about research he conducted at the National Institutes of Health while on sabbatical a few years ago.

While working with NIH researchers, Nolan developed mathematical models to assist with genetic recombination — the process where genetic material from parents and grandparents get mixed up and passed to offspring — in locating disease chains. Simply, he was using math to help determine how genetic traits recombine to form disease.

Nolan’s work is an example of just one of the many areas that math can have an impact in the sciences.

"For some people, it’s surprising to think that you can do useful things with math," he said. "I’m afraid people have a horrid experience with math in school. But math is very useful for solving all types of technological and scientific problems."

Math is just one of many disciplines that can dovetail with the study of genetics. Kim Leighton’s work on genetics and morality brings together philosophy and hard science. Leighton will be presenting her talk, "The Double Bind of the Genetic Tie," at DNA Day.

Leighton, an assistant professor in the Department of Philosophy and Religion, is at work on a book about a person’s moral right to know his or her genetic origins. Her research questions the claim underlying the "right to know" view that to whom we are "tied" genetically is necessarily morally valuable information.  

"I argue that a side-effect of 'right to know' arguments against anonymous gamete donation is a reduction of the value of family to genetic relatedness. It’s a move I see as having morally harmful consequences," Leighton said.

Other presenters participating in DNA Day at AU include Director of Undergraduate Laboratories Maria Gomez-Serrano, Chair of the Department of Chemistry Jim Girard, and Albert Cheh, chair of the Department of Environmental Science.