Cathleen Small - Barbara McClintock: Cytogeneticist and Discoverer of Mobile Genetic Elements

Barbara McClintock, famous for discoveries she made while studying maize genetics

INTRODUCTION

A BRIEF HISTORY OF BARBARA MCCLINTOCK

B arbara McClintock, one of the most important figures in the history of cytogenetics, actually lived in relative anonymity until 1983, when she was awarded a Nobel Prize in Physiology or Medicine. At that time, she was only the third woman to win an unshared Nobel Prize in science, and she was the first woman to do so in that particular category. The sciences wereand to a large extent still area primarily male-dominated field, so having a female scientist who spent her career quietly studying maize plants take the premier prize in the sciences was quite amazing.

But it really shouldnt be. Barbara McClintocks contributions to her field were nothing short of extraordinary. She was born when the field of genetics was just emerging, and she was responsible for some of the most important advances in cytogenetics in the twentieth century, including the identification of ring chromosomes and the breakagefusion-bridge cycle, as well as the discovery of mobile genetic elements, or jumping genes, as they were called.

McClintocks work with mobile genetic elements is what ultimately won her the Nobel Prize, but the accolade came nearly forty years after her initial discovery. For decades, fellow scientists had discarded her theories of transposition, and some even thought she was crazy. But McClintock quietly and without fanfare continued her research, and in the late 1970s, the veracity and value of her discovery became apparent when molecular geneticists recognized the same process that McClintock had tried to describe nearly four decades before. Using electron microscopes and examining cells at the molecular level, molecular geneticists were able to clearly see the very results that McClintock had found decades earlier, using much more primitive technology.

McClintock was interested in plant cytogenetics rather than molecular biology, but her discoveries about the nature and behavior of chromosomes and genes were invaluable to the research later molecular biologists have done with regard to chromosomal conditions, disease, and bacteria.

The reasons why McClintocks early discoveries of mobile genetic elements were cast aside cant be pinpointed with absolute accuracy. Some may have doubted the ability of a woman in that era to produce such an extraordinary finding, but more likely is the fact that McClintocks work was so incredibly complex that even trained scientists couldnt fully understand it. McClintock knew that and tried to simplify her findings, but they were still highly theoretical and incredibly complicated, so many in the field chose to ignore the results she kept trying to present. Eventually, McClintock simply gave up trying to present her findings and went about her work quietly, secure in the knowledge that she was correct in her hypotheses. The results her maize plants showed her were enough to convince her that even if the majority of the scientific community didnt believe her, she had made a very important discovery. A lack of belief from her community wasnt about to cause her to lose faith in her work, and she had a few supporters who never doubted her even when the rest of the community did.

Barbara McClintock never wanted to be considered a feminist iconshe felt she was too outside the box to ever be any sort of role model for women. Yet despite her personal feelings about being a feminist, she was just that: she refused to accept that a woman could not be successful in a male-dominated field, and she refused to accept less than what her male colleagues hadnot in terms of pay, but in terms of respect for her work. Her gender was relatively a nonissue in McClintocks eyes; she was first and foremost a scientistand a brilliant one.