When Florence Bell first came to Leeds in 1937 to undertake a PhD, she could have had little idea that she was destined to become a media sensation. She would probably have been disappointed, however, to discover that it wasn’t her scientific research that had caught the attention of the press.
On seeing the headline “Woman Scientist Explains” in the Yorkshire Evening News on 23 March 1939, a reader might easily be forgiven for thinking that some fundamental law of physics had been shattered – or a new zoological specimen, previously unknown to science, discovered.
Yet whilst the newspaper was preoccupied with telling readers that Florence was a “slim 25-year old Cambridge University graduate” what they had overlooked was that she was also one of the pioneers of a bold new science that would transform our understanding of biology.
At first sight, the subject of Florence’s research might not send scientific pulses racing. Her PhD thesis described the study of proteins found in jellyfish, sharks’ fins and certain rare diseases of hair. While this might seem like an eclectic range of subjects, they all had one thing in common. Each was a fibrous protein or what her supervisor, the scientist William Astbury, described more poetically as “the chosen instrument in the symphony of creation.” Thanks to his early studies of wool, Astbury had established himself as an international authority in the study of these fibrous proteins.
But the impact of Florence’s work would go way beyond the textile mills of West Yorkshire because she was studying a very different kind of biological fibre. Like wool, it was white and stringy but it wasn’t made of protein. This fibre was made of DNA – the material that we now know to be the carrier of genetic information.
Florence makes the news for being a female scientist
"Miss Florence Bell, a 25-year-old graduate of Cambridge University, explaining the fibre test for wool at an exhibition held in conjunction with a conference on industrial physics, which opened to-day at Leeds University."
This image showed for the first time that the methods of x-ray crystallography could reveal the structure of DNA
Photo: Special Collections, University of Leeds
In 1938, Florence took x-ray pictures of DNA, which William Astbury described as “the chosen instrument in the symphony of creation.” Photo courtesy of her son, Chris Sawyer
Florence used x-ray crystallography, which Leeds-based physicist Sir William Bragg and his son Lawrence had developed in 1913, and for which they were awarded the Nobel Prize in Physics two years later. The method scattered x-rays to work out the exact arrangement of atoms and molecules in a crystal. It required a high degree of practical skill and mathematical understanding – both of which Florence Bell had in abundance.
She had learned to use x-ray crystallography whilst reading Natural Sciences at Girton College Cambridge, before moving to Manchester to continue work with Lawrence Bragg himself. When Astbury wrote to Bragg, asking whether he could recommend a skilled x-ray crystallographer, Bragg had replied to say that he had no hesitation in recommending Florence, describing her as an “excellent candidate” who is “capable and experienced and really gets on with the job.”
Once at Leeds, Florence sometimes challenged Astbury when his own excitement ran ahead of his results and she quickly earned the title of his “vox diabolica”, or devil’s advocate. Astbury entrusted Florence with the task of taking x-ray pictures of DNA. But taking an x-ray image was both tedious and dangerous. The exposure times could be in excess of ten hours and setting up the camera to take a picture required a lot of stumbling around in a darkened room in close proximity to high electrical voltages, and red hot x-ray tubes that were emitting high energy radiation.
Her hard work was to be an important milestone. At a time when their function was unclear, Florence recognised that nucleic acids such as DNA might have some key function in biology. In her PhD thesis she envisioned that “possibly the most pregnant recent development in molecular biology is the realisation that the beginnings of life are closely associated with the interactions of proteins and nucleic acids.”
Although the particular model she proposed for how DNA might function is today known to be wrong, this doesn’t mean that her work was without value. Far from it in fact, for the publication of her x-ray images of DNA in 1938 showed for the first time that the methods of x-ray crystallography could successfully be used to reveal its structure.
Her photograph laid the foundations for later x-ray studies of DNA made by the scientists Rosalind Franklin and Raymond Gosling which then helped James Watson and Francis Crick to eventually solve its structure. Florence meanwhile had already anticipated profound implications for research in this area, saying “the limits of our horizon widen beyond imagination. We shall have glimpsed at last what we are.”
Just as Florence’s work on DNA seemed to be gathering momentum, it was brought to an abrupt end. In 1941 she was summoned for war service and joined the Women’s Auxiliary Air Force (WAAF) where she worked on the development of airborne radar systems.
Astbury wrote to the War Office pleading that she be allowed to remain in his laboratory as he “could hardly carry on without her help.” But even had the War Office been willing to release Florence from her war duties, Astbury’s efforts would have been in vain.
In January 1943, Florence wrote to the registrar of the University of Leeds to thank him for keeping her post open, but explained that, as she was now married to an American serviceman called Captain James Sawyer, she would soon be leaving Britain to start a new life in the United States.
Having settled in the USA, Florence worked as a research chemist for a petroleum company before giving up her career to look after her family. When Florence died in 2000 whilst visiting her sister in the UK, her official occupation was recorded as having been a housewife. Yet “Bell should be recognised as another “great” in x-ray crystallography, alongside Marie Curie and Rosalind Franklin,” says Erin McNeill, Physics Outreach Officer in the School of Physics and Astronomy at Leeds. Florence’s contribution may have been overlooked, but the University can be proud of her legacy.
Swiss scientist Friedrich Miescher isolates a grey mildly acidic substance from the nuclei of white blood cells that he obtained by scraping pus from discarded surgical bandages. This substance, which he calls “nuclein”, is later shown to be DNA.
On the basis of estimates made of its chemical composition, the chemist Phoebus Aaron Levene proposes that DNA is made up of simple repeating units of the same four chemicals. Known as the tetranucleotide hypothesis, this leads most scientists to conclude that DNA is a very dull, repetitive molecule, and therefore a very unlikely candidate to be the carrier of genetic information.
Florence Bell at the University of Leeds makes the first successful x-ray study of DNA fibres proving that x-ray crystallography can be used to reveal its molecular structure.
The US microbiologist Oswald Avery and his colleagues Maclyn McCarty and Colin MacLeod at the Rockefeller Institute show that DNA is able to confer on non-virulent pneumococcus bacteria the ability to cause disease. This is the first strong evidence that DNA might be able to carry biological information. Bell’s supervisor at Leeds, William Astbury hails this as “one of the most remarkable discoveries of our time.”
Using a method of chemical analysis called partition chromatography that was developed by Archer Martin and Richard Synge whilst working at the laboratories of the Wool Industries Research Association (WIRA) in Leeds, the US biochemist Erwin Chargaff demolishes the idea that DNA is just a dull repetitive molecule and opens up the possibility that it may carry biological information through its chemical make-up.
A year before the now famous ‘Photo 51’ was taken by Rosalind Franklin and Raymond Gosling at King’s College London, Elwyn Beighton takes identical x-ray images of DNA whilst working in the new Department of Biomolecular Structure at Leeds.
Using x-ray crystallography, Rosalind Franklin and Raymond Gosling at King’s College London obtain a photographic image of DNA that shows a pattern of black spots arranged in the striking shape of a black cross. Known as ‘Photo 51’ this image suggests the molecule is coiled up into a helical shape and is one of several important clues to identify the structure of DNA.
James Watson and Francis Crick announce in the journal Nature their model of the double-helical structure of DNA. This structure explains how the molecule can copy biological information from one generation to the next.
Watson, Crick and Maurice Wilkins are awarded the Nobel Prize in Physiology or Medicine for their discovery.
The Astbury Centre for Structural Molecular Biology at the University of Leeds is a buoyant research centre involving approximately 500 research scientists spanning physics, chemistry, medicine and biology. “We are proud of the pioneering work of Bill Astbury and his student Florence Bell,” says Professor Sheena Radford, FRS, Astbury Professor of Biophysics, Director of the Centre.
“These early pioneers of molecular biology were ahead of their time for two major reasons. First, they were fascinated by the structure of biological fibres, such as found in our DNA as well as in hair and skin, and were amongst the first to try to understand how these structures work by taking pictures of them using the powerful tool of x-ray diffraction. Today this technique is still used to understand the structures of biological polymers including those that have function, as well as give rise to disease: a major research topic in the Astbury Centre today.
“Secondly, we are proud that even in these long-ago days, Astbury was highly supportive of Florence Bell and recognised her talents, when women in science, especially in the physical sciences, were rare indeed. Some of the very best discoveries in science have been made by women, with other examples including Marie Curie, Dorothy Hodgkin and Ada Yonath to name but a few. These women are an inspiration today, just as much as they were in the days of Astbury and Bell.”
Left: Dr Rebecca Thompson uses the University’s new electron microscopes at the Astbury Biostructure Lab
Photo: Simon and Simon