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Image reconstruction in electron microscopy


Using 3D electron microscopy to understand viruses
Aaron Klug Scientist
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So you see, so before I actually developed the theory of three dimensional imagery construction we already had understood that what you saw on the electron microscope was a projection of the structure by making models of the kind that I've just illustrated on the... on the board.

[Q] This also has been seen with TMV with the optical diffraction.

Oh, yes, yes, I've forgotten about that. I also introduced optical diffraction where you took an electron micrograph of a periodic object and you sent a parallel beam of light onto it. And it gave you basically a diffraction pattern, which you could deduce the repeating features. That was done optically and it was the first time and sort of rather obvious. I think I actually arose, got to that because I was, this time I was a teaching fellow of Peterhouse, my college in Cambridge and I was teaching optics among other things as well. And so I must have... must have had a... jump from the optical diffraction... By this time, this was now by the 19... middle '60s, '65, '68, and so looking back on it, it's hard to disentangle the different strands which fed this. It was interplay of the project to understand virus structure... and the... trying to learn how to use the electron microscope to understand what the pictures were. And the real point was that the electron microscope had a large depth of field, people say depth of focus, but the correct word is depth of field; so everything in the line of view is projected like an X-ray image. And that was the first-time people mentioned that and the way to do that was take a series of pictures until we had been taking... what had been done was, when we were building models we interpreted the different views as particles lying in different rotations, different orientations. And so, why rely upon them, why not take a specimen and tilt them in different orientations. And we put this to great effect, and I think we were the only lab in the world that was... well, we were the only lab in the world that was doing all this. And we were able to interpret not only virus pictures but others as well and other things as well. And there we met with a lot of opposition from the electron microscopists certain professional electron microscopists. There was a meeting in 1960... '50, I think it was Turkey in 1969, and we published a paper, DeRosier and myself, who came to work with me on this image reconstruction as we called it. In 1969 there was a meeting of the electron Microscopy Society of America where a man called [Lorenzo] Sturkey called the whole thing a load of crap, that's what he said publicly, I wasn't there. But David DeRosier, who was my visiting post-doc was there, and because at that time they thought that you couldn't solve the structure by electron microscopy because of multiple scattering. Because these are fairly strongly scattering objects, but we showed very clearly that it was single scattering that was basically dominating all this. This took many years to establish, so in the end, we did establish three-dimensional electron microscopy which I would like to have called it. But that could be misinterpreted because the people called three-dimensional electron microscopy the way that you could build up a structure in a series of sections. People cut sections of tissues or particles and built them up place by place, and that was called three-dimensional electron microscopy.

Born in Lithuania, Aaron Klug (1926-2018) was a British chemist and biophysicist. He was awarded the Nobel Prize in Chemistry in 1982 for developments in electron microscopy and his work on complexes of nucleic acids and proteins. He studied crystallography at the University of Cape Town before moving to England, completing his doctorate in 1953 at Trinity College, Cambridge. In 1981, he was awarded the Louisa Gross Horwitz Prize from Columbia University. His long and influential career led to a knighthood in 1988. He was also elected President of the Royal Society, and served there from 1995-2000.

Listeners: Ken Holmes John Finch

Kenneth Holmes was born in London in 1934 and attended schools in Chiswick. He obtained his BA at St Johns College, Cambridge. He obtained his PhD at Birkbeck College, London working on the structure of tobacco mosaic virus with Rosalind Franklin and Aaron Klug. After a post-doc at Childrens' Hospital, Boston, where he started to work on muscle structure, he joined to the newly opened Laboratory of Molecular Biology in Cambridge where he stayed for six years. He worked with Aaron Klug on virus structure and with Hugh Huxley on muscle. He then moved to Heidelberg to open the Department of Biophysics at the Max Planck Institute for Medical Research where he remained as director until his retirement. During this time he completed the structure of tobacco mosaic virus and solved the structures of a number of protein molecules including the structure of the muscle protein actin and the actin filament. Recently he has worked on the molecular mechanism of muscle contraction. He also initiated the use of synchrotron radiation as a source for X-ray diffraction and founded the EMBL outstation at DESY Hamburg. He was elected to the Royal Society in 1981 and is a member of a number of scientific academies.

John Finch is a retired member of staff of the Medical Research Council Laboratory of Molecular Biology in Cambridge, UK. He began research as a PhD student of Rosalind Franklin's at Birkbeck College, London in 1955 studying the structure of small viruses by x-ray diffraction. He came to Cambridge as part of Aaron Klug's team in 1962 and has continued with the structural study of viruses and other nucleoproteins such as chromatin, using both x-rays and electron microscopy.

Tags: Microscopy Society of America, David DeRosier, Lorenzo Sturkey

Duration: 3 minutes, 59 seconds

Date story recorded: July 2005

Date story went live: 24 January 2008