Florence Bell, the “new dark lady of DNA” who helped us understand what we are made of

when the diary Yorkshire Evening News reported on a speech given by 25-year-old physicist Florence Bell at a conference in Leeds, England, in 1939, it was not her science that made the headlines, but simply the fact that she was a woman doing science .

What neither the writers who came up with the headline “Woman Scientist Explains” nor her readers could have known is that, in the course of her doctoral research, this particular scientist had quietly laid the groundwork for one of the milestones most important science of the 20th century: the discovery of the structure of DNA.

With chapters describing the structure of protein fibers in jellyfish, shark fins, and hair, Bell’s doctoral thesis might seem like an unlikely milestone in biology.

But among these, one chapter stands out.

One part of Bell’s work describes how X-rays could be used to reveal the regular, ordered structure of a biological fiber that was called “timonucleic acid” at the time.

Today, thymonucleic acid is known by the more familiar name of deoxyribonucleic acid, or DNA.

Bell’s X-ray method would become a vital tool in finally revealing the now well-known double helix shape of DNA that allows you to copy genetic information.

Devil’s lawyer

Bell, who was born in 1913 in London, was one of a growing number of female students studying natural sciences at the Girton College of the University of Cambridge.

After leaving Cambridge in 1936, Bell first spent a short period in Manchester with Lawrence Bragg, who, along with his father William, had received the Nobel Prize for Physics in 1915.

The pair had shown how X-rays could be used to reveal the arrangement of atoms and molecules in simple crystals like salt.

In 1937, Bell moved to the University of Leeds to take up a position as a research assistant to physicist William Astbury, who was applying Bragg’s methods to the study of wool and other biological fibers.

Astbury X-ray studies of proteins in wool fibers revealed that its structure was like a molecular chainor necklace, formed by joining smaller chemicals called amino acids.

That molecular necklace could be stretched or compacted.

Although this may not seem significant, the fact that these proteins could change shape turned out to be crucial to understand how they worked.

Astbury’s studies of wool would transform our understanding of biology at the molecular level.

Emboldened by his success with wool, Astbury began to expand his network to study other biological fibers.

To do this, he needed another pair of expert hands in this new method of X-ray analysis.

It was then that Florence Bell arrived.

Because of his keen intellect and willingness to challenge his ideas, Astbury called Bell his “devil’s advocate.” And he assigned him the task of using X-rays to study DNA.

clipped wings

Taking an X-ray image was not easy.

It required exposure times of 10 hours, working in a dark room in close proximity to high electrical voltages and very hot X-ray tubes.

But Bell’s skill and tenacity paid off, and in 1938, based on X-ray images she had taken, she and Astbury proposed an early model of the structure of DNA.

That model would later give James Watson and Francis Crick a vital foothold when they began their own work on DNA.

Unfortunately, just as it was taking flight, Bell’s work on DNA came to an abrupt halt.

In 1941 she was called up for military service in the Women’s Auxiliary Air Force. According to one of her sons, Chris Sawyer, during her service she took the first steps in the development of radar (detection and radio range).

Meanwhile, Astbury begged the War Office to allow Bell to remain in his lab, but his pleas were to no avail.

The University of Leeds even kept his position vacant, but Bell never returned.

the new dark lady

After marrying a US military officer, Bell immigrated to the United States, where she worked as an industrial chemist before giving up her career to care for her four children.

Presumably reflecting this change in circumstances, when she died in 2000, her occupation on her death certificate was recorded as “housewife”.

Sawyer recalled that later in her life, her mother liked to claim that one of her greatest achievements was being the first woman in the Royal Air Force to wear trousers. But Bell was being modest.

With his X-ray studies of DNA, Bell not only gave Watson and Crick a vital foothold, but also paved the way for Rosalind Franklin, whose own work in that field was a key contribution to resolving the structure of the material. genetic.

Franklin has been played by Nicole Kidman in the stage play “Photo 51″, has a Mars Rover named in her honor and a new novel about her: thankfully she is no longer “the dark lady of DNA” that she once was.

Perhaps it is now Florence Bell who truly deserves that title.

* Kersten Hall is an author and Honorary Fellow of the Faculty of Philosophy, Religion and History of Science at the University of Leeds. Florence Bell’s story is told in the revised edition of Kersten’s book, The Man in the Monkeynut Coat: William Astbury and How Wool Wove a Forgotten Road to the Double Helix, to be published in paperback by Oxford University Press. in March 2022.