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The Amber mutants


How amber mutants were so-called
Sydney Brenner Scientist
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There was one experiment which really was the kind of last dying whimper of the… well, it was a little bang I would say, of the original program. The original program was to look at the protein and then by doing genetics on the DNA and chemical mutagenesis is to work out the sequence of the DNA. That was the answer, i.e. the sequence of the coding. And the only place where that succeeded was with the nonsense codons. And that, that went roughly as follows. It had been known that some codons the… some mutations gave you nonsense. That had been discovered in the R2; because Seymour Benzer invented a little trick where he had a gene fusion and he could show he could turn off, in this gene fusion, the function of gene B, by some mutants in gene A, showing that these were important drastic mutants. I mean, we later used that to show that proflavine made very severe effects; that they could turn this off. So then we had this idea that they were nonsense, but we didn't know what was nonsense. Now, our work on the acridine mutants had shown us that a lot of the mutations, a lot of the codons had to be sense. That's because we could get frame-shifts over longer… over long regions. But we also knew that there was some nonsense. And so we started to work on these mutants; they were suppressible mutants, and I… and their history is quite interesting, because there were two strains of E. coli, and there were certain mutants that grew on one and didn't grow on the other, and in fact Seymour Benzer used that with the R2s, and so they then asked in Pasadena, 'Can we get this for other genes?' And so they called all the students together and said, 'We want you to do pick and stab, because you have to test each plaque individually, and the first one who finds the mutant we will call this after his mother'. Okay. So the first student to find the mutant was a man called Hilliard Bernstein. All right, now you couldn't call them Bernstein mutants, but amber – Bernstein is the German for amber. So these mutants were called amber mutants. And that's how they remain, because they were called after Hilliard's mother who was also a Bernstein of course.

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.

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.



Listen to Lewis Wolpert at Web of Stories



Tags: Pasadena, Seymour Benzer

Duration: 3 minutes, 3 seconds

Date story recorded: April-May 1994

Date story went live: 24 January 2008