Rosalind Franklin: Beyond the Double Helix
(Inside Science) -- If you’ve heard the name Rosalind Franklin, you’ve probably also heard the names James Watson and Francis Crick. Watson and Crick form the famous duo most widely credited with figuring out the spiral staircase shape of DNA, and Franklin’s public image has become inextricably linked to the story of how it all happened.
In Watson’s rendition of the tale, which he published in the 1968 book “The Double Helix,” Franklin was belligerent, reluctant to collaborate, and struggled to interpret her own data. Watson commented on her looks and dress and gave her a nickname -- Rosy -- that she never used herself. The account inspired a backlash, and in many subsequent tellings, Franklin became the wronged heroine whose data was stolen and whose intellect was suppressed by the patriarchal male establishment. (Watson’s epilogue to “The Double Helix” admits his early impressions of Franklin, which he recounted in his book, were often wrong, and notes her many achievements.)
Franklin’s second biographer, Brenda Maddox, considered both stories a disservice to her subject. In a 2003 article in the scientific journal Nature, Maddox wrote that the story of Franklin as a feminist icon was a powerful myth that grew until it “overshadowed [Franklin’s] intellectual strength and independence both as a scientist and as an individual.” The 100th anniversary of Franklin’s birth, on July 25 this year, provides an opportunity to recall the full breadth of her scientific contributions.
It’s true Franklin played a pivotal role in the discovery of the structure of DNA in the early 1950s. Watson and Crick’s thinking was guided by photographs and calculations that Franklin and her graduate student Raymond Gosling painstakingly made, and which were shown to Watson and Crick, likely without Franklin’s knowledge. Plays, rap battles, commemorative coins, and many written accounts have focused on a particular piece of this data: the famous “photograph 51.” In his book, Watson wrote that “The instant I saw the picture my mouth fell open and my pulse began to race... the black cross of reflections which dominated the picture could arise only from a helical structure... mere inspection of the X-ray picture gave several of the vital helical parameters.”
In reality, Watson was probably playing up his own “Eureka!” moment for the sake of a good story, said Matthew Cobb, a geneticist at the University of Manchester in the U.K. who has written extensively about the race to discover the structure of DNA.
Photo 51 was taken by directing a beam of X-rays at a thin fiber of DNA. When the X-rays encountered the electrons in the DNA’s atoms, they were redirected at specific angles, forming a pattern of light and dark patches on the X-ray film. To make sense of X-ray images like Photo 51, scientists must perform numerous mathematical calculations to reconstruct the paths that the X-rays take, and the way they interfere with each other.
Researchers had done enough analysis by the time Watson laid eyes on Photo 51 to know that corkscrew-like structures called helixes should produce cross shapes in such X-ray images. The spacing between the spots on the cross could be used to calculate how tightly the helix was wound. But prior experiments had already led many scientists to believe that DNA was helical, Cobb said. Key mysteries, like the number of strands and how the whole thing fit together, remained unsolved.
It was some of Franklin’s numerical data that likely played a bigger role than just one picture, Cobb said. She had written it up in a report that was shown to Watson and Crick as Franklin was preparing to leave King’s College in London and pursue other research at Birkbeck College. Franklin had calculated key details that could be interpreted in terms of the spacing and the symmetry of the groups of atoms in her DNA samples.
When Crick saw Franklin’s numbers, he recognized that the symmetry they described could be achieved by two helical strands running in opposite directions. Crick’s mind was primed for this insight because he had worked on a mathematical framework for interpreting data generated by taking X-ray images of helical molecules as part of his Ph.D. thesis, Cobb said. Franklin continued to analyze her data until she left King’s, and the work in her notebooks showed she was close to getting the right structure, according to Aaron Klug, later her colleague at Birkbeck, who published two papers in Nature in 1968 examining her work on DNA. Franklin had a philosophical difference with Watson and Crick, Cobb noted. She preferred to gather the data, and then analyze it. Watson and Crick charged ahead in their modeling even as early experimental data was still coming in. They were not afraid to propose models that failed under scrutiny before they ultimately got it right. In addition, at the beginning Franklin was simply not as obsessed with DNA as Watson was, Cobb said. The fact that we still focus so much on this aspect of her life is evidence that in some ways Watson is still shaping how we think about Franklin, Cobb said.
The whole DNA saga was a brief 2-year interlude in Franklin’s prolific scientific career, which was cut short when she died of ovarian cancer at the young age of 37 in 1958. Franklin began her career studying coal, and she ended it studying viruses. Her measurements of the size and shape of tiny holes in various types of coal and the way it burned had implications for a wide range of technology, from gas masks to smelting plants. After pivoting away from DNA, Franklin and her colleagues figured out the structure of the tobacco mosaic virus, which infects tobacco plants. She studied other plant viruses, and at the time of her death had turned her attention to polio.
The inscription on her tombstone in London reads, in part, “Her research and discoveries on viruses remain of lasting benefit to mankind.”
“She died proud of her world reputation in the research of coals, carbons and viruses,” Maddox wrote in her Nature essay. “Given her determination to avoid fanciful speculation, she would never have imagined that she would be remembered as the unsung heroine of DNA.”
Science, the endeavor to which Franklin devoted herself from a young age, is not a straight line to the truth, but its zigs and zags typically add up to take it in the overall right direction. Perhaps the story of Rosalind Franklin will take a similar path, eventually settling into a narrative that captures her scientific life in more of its beautiful richness.