Recorded: 20 Feb 2001
Experiments rarely actually have that A-ha! moment and generally speaking when you do have that moment, it's something that most people would find quite mundane. You know, you already know something is probably the case and then you do a series of experiments to show that it is or isn't. And it usually takes several experiments before you convince yourself that it's true and so it's rare that the very last one really does it for you. I think if I had to remember anything strongly, it would be when I was at Berkeley. I found this pattern of variegation in plants, which was similar to what McClintock used to study. I knew that this was a mutation in a gene that I was trying, actually, to isolate molecularly and I knew that the variegation would have something to do with epigenetics. Because we had molecularly isolated the transposable element that we thought was responsible for this mutation, it was possible to simply isolate DNA literally from the two halves of the variegated plants (if you imagine a plant that's half white and half green), make DNA, and do a very simple experiment to show that in fact the DNA was different in the two halves. One was methylated. DNA methylation was a fashionable thing at the time and it turned out that methylation was really responsible for the variegated pattern... Then looking at the way that pattern changed during development was a key thing. And I still look back on that time as being very important time. I couldn't say that it was one moment when I developed a film in the dark room or something. For me, things rarely work the first time anyway; I usually have to do them a few times.
Rob Martienssen is a plant molecular geneticist and professor at Cold Spring Harbor Laboratory. He received his Ph.D. from Cambridge University in 1986 and did postdoctoral research at the University of California, Berkeley.
As a young scientist, he worked closely with Barbara McClintock. He currently studies plant epigenetics and development using functional genomics. He was awarded the Kumho International Science Award in Plant Biology and Biotechnology (2001).