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.

Dr. Robert Martiennsen is a plant biologist, Howard Hughes Medical Institute-Gordon and Betty Moore Foundation investigator, and professor at Cold Spring Harbor Laboratory. Martiennsen attended Emmanuel College, Cambridge, completing his BA in 1982 and continuing on to his PhD in 1986 on the molecular genetics of alpha-amylase gene families in common wheat. He received an EMBO postdoctoral fellowship with University of California, Berkeley. In 1989, he was hired as a principal investigator at Cold Spring Harbor Laboratory. As a young scientist, he worked closely with Barbara McClintock. His awards and honors include the Newcomb Cleveland Prize, McClintock Prize, and Science’s Breakthrough of the Year in 2002 and the Kumho International Science Award in Plant Biology and Biotechnology (2001).