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Views | Duration | ||
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101. Using magnesium to compete with caesium: the experiment | 1 | 326 | 06:28 |
102. Still working on mutagenesis | 243 | 01:01 | |
103. Acceptance of the paper | 305 | 04:34 | |
104. François Jacob and genetics | 349 | 05:06 | |
105. The curtain opens: the importance of conversation | 327 | 03:54 | |
106. Internal suppressors: the Theory of Mutagenesis | 264 | 04:07 | |
107. Another hypothesis: base additions and deletions | 215 | 01:40 | |
108. Sense and nonsense: the Commaless Code | 255 | 03:36 | |
109. Using frame-shift to determine the size of the genetic code | 272 | 04:40 | |
110. Exceptions to the frame-shift rules | 189 | 02:35 |
I have to tell you that there were many exceptions. There were some things that didn't obey these rules. And the question is: you can ask whether in science you should at least tell people about this. So you… what we had was a huge body of information which was entirely self-consistent and of course with a concept of the barriers, that as certain frame-shifts generated mutants themselves and therefore were not compatible. We had that all worked out at the time, fortunately, otherwise it wouldn't have made sense. And the question is: what happens to all these exceptions? So you have the Don't Worry hypothesis: there… there'll be an explanation for them. As it turned out it took about five more years to work through all the exceptions, and the remarkable thing is that each one of them had a different and special explanation. Some of them were very remarkable. For example, there was one mutant which appeared to suppress itself. We could never isolate a suppresser. And it turned out that what that mutant did was duplicate itself, and in the duplication – that is, the junction of the duplication – introduced the third phase shift. So you had plus, you had a junction point which was plus, and then you had the mutant again which was plus. And of course... so we proved this by showing that the mutant mapped on both sides of itself. That was what… as a completely different explanation. Another set of mutants, we made a strong prediction that no base analogue mutants should be revertible by acriflavine. We found some. And vice versa. It turned out that those were due to new start signals being produced. And so when you get something like this, it tells you that all the exceptions, each of which cannot be explained by the coherent theory… that the coherent theory remains, then. And it is… was wise to take all of these exceptions which showed no relationship amongst each other and put them on one… we didn't conceal them; we put them in an appendix.
South African Sydney Brenner (1927-2019) was awarded the Nobel Prize in Physiology or Medicine in 2002. His joint discovery of messenger RNA, and, in more recent years, his development of gene cloning, sequencing and manipulation techniques along with his work for the Human Genome Project have led to his standing as a pioneer in the field of genetics and molecular biology.
Title: Exceptions to the frame-shift rules
Listeners: Lewis Wolpert
Lewis Wolpert is Professor of Biology as Applied to Medicine in the Department of Anatomy and Developmental Biology of University College, London. His research interests are in the mechanisms involved in the development of the embryo. He was originally trained as a civil engineer in South Africa but changed to research in cell biology at King's College, London in 1955. He was made a Fellow of the Royal Society in 1980 and awarded the CBE in 1990. He was made a Fellow of the Royal Society of Literature in 1999. He has presented science on both radio and TV and for five years was Chairman of the Committee for the Public Understanding of Science.
Tags: mutation, mutants, duplication, phase shift, acriflavine
Duration: 2 minutes, 36 seconds
Date story recorded: April-May 1994
Date story went live: 24 January 2008