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Confocal microscope – a great step forward


Creation of the first confocal microscope
Aaron Klug Scientist
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I was involved in the creation of the first practical confocal microscope... not involved, I actually started it. Now the confocal microscope was the first of its kind, brought in a great deal of money in the early years. It was made commercial by a company called Bio-Rad which I'll tell you about in a moment, and brought in a good deal of money when they sold, but because of very bad management, absolutely terrible management, they lost out to the companies like Zeiss and Leica, who followed later and actually didn't break the patents, but they simply outsold them by introducing new versions which had more facilities and so on. But the confocal microscope was the first microscope where you could see the tissues of a cell in a detail which nobody had ever seen before. And the way it came about was that I had read a paper... the confocal microscope was invented more than 30 years ago, but never made practical, the idea being that you scanned the picture and put it together on a computer. It was done by this Marvin Minsky, a very brilliant... he's sort of a near genius, invented all sorts of things in psychology, artificial intelligence, and so on. He proposed it in the 1950s, it must have been, but nobody built it. But there were people who were building confocal microscopes in Oxford, where they had moving stages rather than a scanning head, which is what the modern ones use, and I knew something about confocal microscopy because at one time we were going to do confocal electron microscopy. This is because the man at the Argonne Lab, what's his name, was building one, and at one time I commissioned AEI to building a confocal electron... what's his name?

[Q] Crewe.

Crewe! Albert Crewe, Albert V Crewe, yes, Albert Crewe. He also introduced the filaments, these gave you high intensity. I can't remember what material it is from which you extract the electrons. But he was a very good inventor. So I knew about the confocal principle, but I read a paper which was sent to me for refereeing by a man in Holland called [Fred] Brakenhoff, and Brakenhoff was building one of these stages... confocal microscopes, and what he had done was to introduce an aperture in such a way that it cut out extraneous noise. He was getting remarkable detail. The paper's purely on chromatin. This was what he regarded as a standard application of confocal microscopy. There are others who have built... the people in Oxford were trying to build one as well, which also had moving stages. And then I realised... so I wrote a report on this, and I realised you can probably get much better or precise illumination if you introduce a system of stops. I mean, I didn't invent it, but I saw... that what Brakenhoff had done, without emphasising it, because I couldn't understand why he got such detail. So I went to John White... John White is a man who was working on the nematode project, the worm that Sydney [Brenner] had set up, and he was doing the anatomy, but he was trying to use optics, by using laser optics to kill cells and developing worm, working together in fact with John Sulston. So he knew something about optics, had been trained as an engineer, he knew something about optics and he knew something about biology. So I went to him and said, 'Look, why don't you go to Oxford and see what they're doing in Oxford, in the engineering department, with this confocal microscope and see if you can adapt it with systems of stops to give you a much better images', and so it turned out he never went to Oxford, but in the Lab we had Brad Amos, who was a... had been a zoologist but interested in microscopes and optics, and he built a new kind of scanning instrument based upon the carbonometer principle which scanned the instrument, and we also got... now the thing about the confocal microscope is that you can get... you can get very high resolution, but you can also get high resolution in the line of view, in the longitudinal direction, and it goes roughly as the square of the abbé which is in the lateral resolution, so in other words you can... with a confocal microscope you also get an optical section, a section optically, so they improved the illumination. They were really very good. It was all done in-house and I got the... I got the Lab to start a project on building their own confocal microscope.

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: Bio-Rad, Zeiss and Leica, Marvin Minsky, Albert Crewe, Fred Brakenhoff, John White, John Sulston, Brad Amos

Duration: 5 minutes, 19 seconds

Date story recorded: July 2005

Date story went live: 24 January 2008