Lederberg on his discovery of conjugation

Well, I was working in Francis' lab since 1942. In early '44, Avery, McCloud and McCarty published their paper on the transformation of pneumococcus with DNA, and it just became obvious to me, and it was to a few people -- it was resisted by some others -- to put it in contemporary terms, that molecular genetics was about to begin, and that this was the medium for it, and that bacteria would be the object of that kind of investigation. Actually, my first experiments after that paper came out were to see if you could transform Neurospora with DNA (I was already skilled at working with Neurospora). They didn't work. Instead we found that some of the mutants of Neurospora that had been thought to be stable could actually rarely but spontaneously undergo reverse mutation. So, that was my first experiment with Francis. We published a paper about that. Then, realizing that Neurospora wasn't working, we decided to turn around and say why to we want to do that, that was so that we could provide a convergence between the chemical approach of extracting DNA and putting it into cells with genetic analysis of being able to cross-hybridize whatever products you had of those transformations, show that there really were genic changes, that you could map them and so forth. So it occurred to me, well, maybe we could turn the reasoning around, and instead of trying to import DNA into Neurospora, maybe we could turn a bacteria into the equivalent of Neurospora by crossing it, and I asked about what the existing status of knowledge was and I found -- read the literature quite deeply on that point -- but it was very confusing, I found nobody had done a genetic study of the matter. And so I decided that it was possible to use the technology that I had learned from Neurospora, and apply it to the question of genetic recombination in bacteria. So, I started those experiments, while I was at Columbia. By this time, I had completely my undergraduate studies, and I was starting medical school. I was staying with Ryan all the way through. I was still working in the lab when I was in medical school, and began doing these experiments in July 1945, and went very slowly. I didn't have a lot to begin with; I didn't have any mutant strains of bacteria, I had to figure out how to make them, I only had a few. And then Francis at one point suggested that maybe I should try to work with [Edward Lawrie] Tatum: he was just coming to Yale, and I think I told that story in the article that I sent you. This was all compounded with history, which was also moving on. I had been in uniform since July 1943. I was enrolled in the V12 training program in the Navy. I was designated to be a future medical officer, and if the war had gone on I would have been redirected in my career. As you know, happily the war ended, as you know, in August 1945, and...we were relieved from service. That also caused some consternation, because the Navy was paying for my education during that time, and I had to figure out some way that I could manage on my own. It was not an easy task, but I did get a job working for Francis. There wasn't much money involved earlier, but he was able to give me an assistantship to enable me to almost make my living while going to medical school. Again, with his help, I was able to get a fellowship, so I was able to go to Yale for a while, so I ended up there almost exactly 50 years ago, in March 1946, arrived in New Haven, continued the experiments that I started, and they proved to be successful very very quickly: within a few weeks.