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Women's History Month: Barbara McClintock

In 1987, Congress declared March as National Women’s History Month in order to call attention to the many contributions of women in society. Each week this March, we’re highlighting the lives of some of these great women in blog posts by some of our notable employees who talk about women who inspired them. This week, Jessie Sexton, Ph.D., our Senior Microbiologist, spotlights Barbara McClintock for her inspiring work in mobile DNA and genetic regulation.

The famous geneticist, Barbara McClintock, never stopped doing what she loved in spite of the many challenges she faced as a female scientist in the early 20th century. And not only did she thrive – she went on to win the Nobel Prize.

Growing up in Connecticut, McClintock knew early on that she wanted to pursue higher education. In spite of discouragement from her mother, McClintock attended Cornell University, where she earned a B.S. in Agriculture, followed by an M.S. and Ph.D. in botany. In 1936, Dr. McClintock found an Assistant Professorship position at the University of Missouri, which was very rare for women at that time. As an academic, she maintained her love of research, observing and describing phenomena that are now biology and genetics textbook fundamentals, including an important process of chromosomal rearrangement known as “crossing over”.

Using maize (corn) as a model system, McClintock studied genetics (how observable traits are controlled by genes) and the structure of DNA itself. By employing a microscope and special staining techniques that she had developed, she was able to visualize maize chromosomes and thus examine genetic events at a cellular level.

In 1943, McClintock settled into a position at the Cold Spring Harbor Laboratory on Long Island. It was here that she made her Nobel Prize-winning discovery of transposons (mobile pieces of DNA that hop around the genome), and the way their movement affects gene expression.

Unfortunately, McClintock’s work on mobile DNA and genetic regulation was so far ahead of its time that she had to wait decades for recognition of its significance. Although she authored numerous papers in the 1930s, she stopped publishing her research findings almost entirely in the early 1950s due to skepticism from her peers. McClintock’s 1951 presentation of her work on transposons and gene regulation was met only with confusion. Other researchers could not understand or follow her conclusions, and so proceeded to ignore them.

To put things in context, at this period in time, Watson and Crick had yet to publish the structure of DNA (done in 1953), and Jacob and Monod’s description of genetic regulation in the bacterial lac operon was a decade away (published in 1961). DNA transposition was not described in other systems until the 1970s when scientists observed its occurrence in bacteria and yeast.

In 1983, McClintock’s work was finally recognized for the genius it was and she was awarded the Nobel Prize in Physiology or Medicine for the discovery of mobile genetic elements. She was the third woman to win an unshared Nobel science prize in the 80 years since the inception of the award.

She lived to 90 years of age, continuing to conduct research at Cold Spring Harbor Laboratories until the time of her death. McClintock was among the most impactful scientists of the 20th century and her dedication and perseverance are still a huge inspiration to many scientists all over the world.