Interview The Eureka Moment: An Interview with Sir Alec Jeffreys Jane Gitschier* Department of Medicine and Pediatrics, University of California San Francisco, San Francisco, California, United States of America In 1984, while tracking the veins of globin gene evolution and panning the human genome for hypervariable linkage markers, Sir Alec Jeffreys accidentally struck gold—he discovered a way to identify any human being by a DNA ‘‘fingerprint’’. To use Jeffreys’ words, he has been ‘‘branded’’ by DNA fingerprint- ing, but he delights in its application and the hook it provides for public curiosity about science. Like Jeffreys himself, I wanted to dig below the surface of this discovery as well as that of another genetic nugget—the intervening sequence—found as a post-doctoral fellow seven years earlier. On the heels of my interview with Adrian Bird (published in the October issue of PLoS Genetics), I made my way to Jeffreys through another branch of the British Rail system. When I arrived at his building on the leafy Leicester campus about 45 minutes early for our appoint- ment, his assistant suggested I get a cup of coffee while Jeffreys finished his experi- ment. I certainly wouldn’t have needed one. Jeffreys (Image 1) is an animated speaker, with a resonant voice and a rapid delivery of succinct clauses strung together in run-on sentences. His story could have cut through anyone’s jet lag. Gitschier: I didn’t realize that you still work in the laboratory. Jeffreys: I certainly do! Gitschier: Tell me about the experi- ment you were just doing. Jeffreys: Right, well, we won’t go into the gory details. Copy number variation [CNV] in the human genome is a real hot topic at the moment. Gitschier: The kind of variations people are looking for in association with autism and psychiatric diseases. Image 1. Sir Alec Jeffreys. Jeffreys: That’s exactly right. It’s a doi:10.1371/journal.pgen.1000765.g001 common phenomenon, and we’ve actu- ally known that for decades. What we’re around the place in forensics, and return- novo copy number variation in the fetal c- doing is going back to some of the ing back to my first love. The experiment globin genes at the single molecule level in absolutely classic examples of CNV. I’m doing at the moment is looking at de both somatic and germline DNA. These are in my favorite gene family— the globin genes—and that’s where I cut Citation: Gitschier J (2009) The Eureka Moment: An Interview with Sir Alec Jeffreys. PLoS Genet 5(12): my scientific teeth. e1000765. doi:10.1371/journal.pgen.1000765 Gitschier: We’re going to be coming Published December 11, 2009 back to that! Copyright: ß 2009 Jane Gitschier. This is an open-access article distributed under the terms of the Creative Jeffreys: Right. So, what I’ve done in Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, my scientific career is this gigantic circle, provided the original author and source are credited. starting off in globin genes, going all * E-mail: [email protected] PLoS Genetics | www.plosgenetics.org 1 December 2009 | Volume 5 | Issue 12 | e1000765 All of this comes out of my work on Jeffreys: Right. And the penny During that experiment, we had to recombination hotspots. And the general dropped then, that this was going to be develop methods for monitoring purifica- feeling was that recombination hotspots the way forward. tion, and the only way we could see to do function at meiosis—they drive allelic I get to Amsterdam, and Piet said, you that was to use Ed Southern’s blotting recombination, and they may well drive canworkonthisifyoulike,butyoumight technique, which at that point was only a ectopic recombination. also like to have a chat with this guy Dick year or two old. Gitschier: Define ‘‘ectopic.’’ Flavell, he’s got a collaboration with So, as we purified the DNA we could Jeffreys: The term ectopic originally Charlie Weissman in Zurich, on trying monitor the fractions just by running them came from yeast and it applied there to a to isolate a mammalian gene. And I out on an agarose gel, doing the Southern situation in which you have a sequence thought—whoa! That’s sounds really blot and then hybridizing with an appro- repeated, say here and there, so that they exciting. The idea of the project was to priate complementary probe. And that not can undergo unequal crossover and cause get to a single-copy gene. No one had ever only worked, but we could actually see the duplication and deletion. ‘‘Ectopic’’ re- done that in a mammalian system. The fragment of DNA we were trying to purify combination means it’s ‘‘out of place.’’ only one we could possibly do, we felt, in the starting EcoRI digest of genomic As of yesterday, I found there is copy was either rabbit a-orrabbitb-globin, DNA. number instability not just in the germline, because the mRNA had been purified. Gitschier: Hadn’t he shown that but in somatic DNA. That largely rules Thegeneisolationwouldbebyphysical before? out meiosis and meiotic recombination purification. Jeffreys: No, Ed was desperately hotspots. Even in the germline it is quite Gitschier: No cloning? trying to get this going. I know Ed clear that the substantial proportion, Jeffreys: Well, cloning came in right at extremely well, and there was a bit of possibly the great majority of rearrange- the end. It simply wasn’t around at the discomfort on my part thinking that we ments, are again pre-meiotic, arising time. It was by hybridization enrichment had trampled on his patch. On the other during germ cell development. We’re with prodigious quantities of DNA [from hand, that is what we needed to do. trying to drill down below the applied rabbit liver]. The experiment was to cut it Having got the ability to detect down to genetics [looking for variation associated up with EcoRI restriction enzyme. Re- the single gene level, we thought we should with disease], to some of the fundamental member, this is back in the days when you see if we could make a restriction map mechanisms, to understand the dynamics couldn’t just buy enzymes off the shelf, you around the gene, which is what we did. of rearrangements in the human genome. had to make them. Gitschier: Were there EcoRI sites in So, if you want to put a simple summary Then denature the DNA and hybridize it the cDNA? on what this lab is about, it’s about human to globin mRNA. This was a two-pronged Jeffreys: No. The cDNA had been DNA diversity and the processes that attack. In Amsterdam we were going to use cloned by Tom Maniatis, and we pretty generate it. the mRNA to pull out the complementary quickly moved over to using his rabbit b- Gitschier: OK! Now let’s get to the strand, heavily enriched, and in Zurich, globin cDNA that he very generously first question on my list, which indeed is Charlie Weissman had managed to make a provided to act as a probe for monitoring. about globin. It’s about the period of your cDNA so he could pull out the other strand, We just wanted to check that everything post-doc in Amsterdam. Why did you go and the idea was to purify our complemen- was OK. And we built up a restriction there and why work with Flavell? tary strands and then meet somewhere in the map around it [on genomic DNA via Jeffreys: OK. I did my D. Phil. at middle to hybridize the two stands back Southern blotting]. Oxford University on human somatic cell together. Then, because this was an EcoRI We then discovered that there was an genetics. Then went to a Biochemical fragment, we could then pop it into a vector EcoRI site right smack bang in the middle Society meeting and chatted with a chap that we hoped someone was about to of the gene! [That meant] our enrichment named Piet Borst, a very senior scientist, develop. experiment was a total disaster, because who at the end said, if you are interested in Gitschier: How were you selecting the we would have purified one end of the doing a post-doc with me, just let me mRNA? gene in Amsterdam, and in Zurich, they know. Jeffreys: We were selecting by attach- would have purified the other end of the And I thought, that’s great, 9cause I ing mercury to the RNA and then gene, and to put them together, there wanted to get out of Oxford, and Holland I capturing it on a thiol column. would be nothing. The flop of the really fancied because the language wasn’t Gitschier: That’s a dangerous millennium that was! going to be a problem; everyone speaks experiment. But, the question then was, what the English. So, I got myself an EMBO fellow- Jeffreys: Oh, the whole thing was hell is the EcoRI site doing in the middle ship to work with Piet on yeast tRNA genes. horrendous. We were using radioactive of the gene? And then we started to do In 1975, the door was clearly opening mercury. more and more fine-mapping and it was on molecular genetics, before that, it Gitschier: But hold on. Since there clear there was a huge gap in the gene. wasn’t worth talking about. was no reason to suspect that there were I remember sitting down with my Dutch Gitschier: Expand on that statement. intervening sequences, what is the point of technician, saying we’ve got the restriction Jeffreys: I remember very clearly.