Who Discovered Jumping Genes that are not permanently fixed on chromosomes and When?

Every researcher in the world accepted that genes were strung along chromosomes in fixed positions like pearls on a necklace. Working alone in a small, windswept cornfield at Cold Springs Harbor, Long Island, Barbara McClintock proved every other genetic scientist in the world wrong.

Carefully studying wild corn, Barbara McClintock found that genes not only can jump, but regularly do jump from one position to another on a chromosome. She found that a few controlling genes direct these jumping messenger genes to shift position and turn on, or turn off, the genes next to them in their new location.

Barbara McClintock’s work became the building block for a dozen major medical and disease-fighting breakthroughs. The 1983 Nobel Prize Committee called Barbara McClintock’s pioneering work “one of the two great discoveries of our time in genetics.”

With a Ph.D. in genetics, Barbara McClintock lived in a trim two-room apartment over the bright-green-painted garage of the Carnegie Institute’s Cold Spring Harbor Research Facility.

A small, slight woman, Barbara stood barely five feet tall and weighed less than 90 pounds. Her face and hands were worn and wrinkled from long exposure to wind and sun.

Cold Spring Harbor is an isolated spot on northeastern Long Island characterized by wind, rolling sand dunes, and waving shore grass. Stooping in a small half-acre cornfield tucked between the facility’s cluster of buildings and the choppy waters of the Long Island Sound, Barbara planted corn seeds by hand one-by-one in carefully laid out rows.

The year 1950 was Barbara’s sixth year of planting, growing, and studying the genes of these corn plants as they passed from generation to generation. She often felt more like a farmer than a genetics researcher.

How Barbara spent her days depended on the season. In summer, most of her time was spent in the cornfield, nurturing the plants that would produce her data for the year, weeding, checking for pests and disease that could ruin her experiments. In the fall she harvested each ear by hand, carefully labeled it, and began her lab analysis of each gene’s location and structure on the chromosomes of each ear. Her lab consisted of one powerful microscope, chemical lab trays, and stacks of journals to record her findings. This work consumed the long hours of winter.

In the spring she split her time between numerical analysis of the previous year’s data and field planning and preparation for the next generation of corn plants.

She carefully tracked color mutations, patterns, and changes year after year and discovered that genes are not fixed along chromosomes as everyone thought. Genes could move. They did move. Some genes seemed able to direct other genes, telling them where to go and when to act. These genetic directors controlled the movement and action of other genes that jumped positions on command and then turned on, or turned off, the genes next to them in their new location.

It sounded like scientific heresy. It contradicted every genetics textbook, every genetics research paper, and the best minds and most advanced research equipment on Earth. At the end of the 1950 harvest season Barbara debated about releasing her results and finally decided to wait for one more year’s data.

McClintock presented her research at the 1951 national symposium on genetic research. Her room had seats for 200. Thirty attended. A few more straggled in during her talk.

She was not asked a single question. Those few left in the room when she finished simply stood up and left.

As so often happens with radically new ideas, Barbara McClintock was simply dismissed by the audience with a bored and indifferent shrug. She was ignored. They couldn’t understand the implications of what she said.

Feeling both helpless and frustrated, Barbara returned to harvest her cornfield and start her analysis of the seventh year’s crop.

It took another 25 years for the scientific community to understand the importance of her discovery.

Barbara McClintock became the first woman to receive an unshared Nobel Prize in Physiology or Medicine. When she died in 1992, one of her obituaries suggested that she might well be ranked as the greatest figure in biology in the twentieth century.

About Karen Hill

Karen Hill is a freelance writer, editor, and columnist. Born in New York, her work has appeared in the Examiner, Yahoo News, Buzzfeed, among others.

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