Birth Date: June 16th, 1902
Date of Death: September 2nd, 1992
Place of Birth: Hartford, Connecticut, US
Place of Death: Huntington, New York, US
Nationality: United States of America
Occupation/Field of Study NOBEL PRIZE IN PHYSIOLOGY AND MEDICINE IN 1983

 

SHE THOUGH IT:

When Barbara McClintock made the most important discovery of her career, scientists failed to understand its meaning immediately, which tells a lot about how brilliant McClintock was for her time.

In her early researches Barbara McClintock developed a technique made for visualizing and identifying chromosomes in maize. This was her first big contribution to maize cytogenetics and it set the stage for all of her later discoveries. In the late 1940s, by examining corn hereditary characteristics, McClintock challenged all existing knowledge and beliefs about genes and their capabilities. Before her discovery, it was thought that genes were stable units linearly arranged in fixed positions on chromosomes; however, she found that some genes can be mobile and change their positions in the genome[1]. Additionally, she discovered that these mobile elements known as transposons, or transposable genetic elements, can control and alter the function of neighboring genes by making them active or inactive[2].

Although not widely accepted from the very beginning, her work did revolutionize maize genetics by completely changing the way scientists understand genetic patterns of inheritance. Today the importance of her work is better understood, mobile genetic structures are being extensively used, lately also in cancer research[3]. Moreover, some of her “early experiments still rank among the twentieth century’s most important biological experiments”[1].

[1] Bertsch McGrayne, Sharon. 2002. Nobel Prize Women in Science: Their Lives, Struggles and Momentous Discoveries. Washington DC: Joseph Henry Press, p.144.

[2] Ravindran, Sandeep. 2012. Barbara McClintock and the discovery of jumping genes. PNAS 109 (50): p.20198.

[3] “Barbara McClintock – Facts”. Nobelprize.org. Nobel Media AB 2014. Web. 18 Jun 2016.

URL: http://www.nobelprize.org/nobel_prizes/medicine/laureates/1983/mcclintock-facts.html

[4] Ravindran, Sandeep. 2012. Barbara McClintock and the discovery of jumping genes. PNAS 109 (50): p.20199.

 

SHORT BIOGRAPHY:

Born as Eleanor in Hartford, Connecticut, the 16 June 1902, her parents renamed her Barbara not long after, so it would better fit her harsh personality. Barbara McClintock had a happy childhood enjoying different types of activities and developing a great willingness to learn. She was much more connected to her father than she was to her mother, who was strongly opposed to the idea of McClintock or any of her sisters attending a university. In fear that an education would make her “unmarriageable”, Barbara McClintock’s mother prohibited her from going to college after she graduated from high school. She applied for admission to Cornell’s college of agriculture only in 1919, with her father’s permission[1].

Very soon she discovered a specific passion toward cytology (the study of cells) so she begun to study chromosomes and their changes. It was thus during her studies that she started building her career as a pioneer of cytogenetic, and her fascination eventually brought her to form some of the most fundamental ideas in genetics.

The leading tools in genetics back then were fruit flies and corn or maize. As Barbara McClintock started her career with maize, she soon found a system to identify its chromosomes by staining techniques, observing differing coloration patterns in kernels of corn, something no one had ever done in maize study. People were confused by her project at first, as Swaby (2015) explains, her experimental methods “were so dense and complicated that they were difficult for her peers to understand”, but very soon there was a group of professors working under the intellectual leading of Barbara McClintock, who didn’t even have her Ph.D. yet[2]. She earned it in 1927 at age of 25, and stayed on Cornell a few more years doing researches, publishing papers and teaching botany. In 1930 with Harriet Creighton, McClintock found a link between chromosomal crossing over during meiosis and the recombination of genetic traits. By 1932, she had already nine articles on maize chromosomes published and made the first genetic map for maize[3]. She was forbidden to become a professor at Cornell’s so she spent the next few years changing job positions and institutions, until 1941, when she accepted a position as a full time researcher at Cold Spring Harbor Laboratory at the Carnegie Institution of Washington. It was there that she discovered transposition, by identifying the Dissociator (Ds) and Activator (Ac) in 1944 – elements that could change position on the chromosome, and could control the genes, by regulating their actions[4]. When she finally showed her outcomes to her colleague researchers, no one was ready to accept the concepts she was explaining. As Swaby (2015) suggests in her book, “McClintock had just laid out a meticulously researched case that genetics was much, much more fluid than what scientists had previously realized, with genes able to switch on and off and change locations”[5]. Nevertheless, there were some scientists who understood the significance and consequences of her breakthroughs right away and McClintock firmly continued to develop her researches and worked on various races of maize.

Barbara McClintock remained at Cold Spring Harbor until 1967, when she officially retired, however, she spent her later years there working with graduate students. She died of natural causes on September 2, 1992.

[1] Ibid., p.20199.

[2] Swaby, Rachel. 2015. Headstrong: 52 Women Who Changed Science—and the World. New York: Broadway Books, p.98.

[3] Ibid., p.149.

[4] Swaby, Rachel. 2015. Headstrong: 52 Women Who Changed Science—and the World. New York: Broadway Books, p.97.

[5] Ravindran, Sandeep. 2012. Barbara McClintock and the discovery of jumping genes. PNAS 109 (50): p.20198.

 

SCIENTIFIC COLLABORATION AND RECOGNITION:

 When Barbara McClintock started her work on maize, genetics was still an abstract and controversial field of study, with the gene being just a term with no professional definitions. Researchers were just beginning to rediscover the work previously done by Gregor Mandela on inheritance pea plants, using fruit flies and maize to study genetics. Because of the lack of understanding of the concepts she was researching by the other scientists at Cornell, but also because of her gender, McClintock conducted most of her scientific work alone. Although she had some followers, who immediately recognized the importance of her visions, a lot of colleagues thought of her research as completely useless.

Today McClintock is considered as one of the most important scientists in genetic research, but her ideas were not widely accepted until the late 1960s and early 1970s, two decades later, when molecular biology finally discovered mobile genetic elements in bacteriophages, and soon in bacteria itself. Lastly, it was in 1982, thirty-five years after her first published report on transpositions, that Barbara McClintock was awarded the Nobel Prize in Physiology or Medicine “for her discovery of mobile genetic elements”[1]. In the press release article following the awarding, the Nobel Assembly wrote: “The discovery of mobile genetic elements by McClintock is of profound importance for our understanding of the organization and function of genes. She carried out this research alone and at a time when her contemporaries were not yet able to realize the generality and significance of her findings”[2].

[1]  “Physiology or Medicine 1983 – Press Release”. Nobelprize.org. Nobel Media AB 2014. Web. 19 Jun 2016.

URL: http://www.nobelprize.org/nobel_prizes/medicine/laureates/1983/press.html

[2] “Barbara McClintock – Facts”. Nobelprize.org. Nobel Media AB 2014. Web. 18 Jun 2016.

URL: http://www.nobelprize.org/nobel_prizes/medicine/laureates/1983/mcclintock-facts.html

 

PRIZES, DISTINCTIONS, HONORS:

1947 – Achievement Award, American Association of University Women.

1957 – Merit Award, Botanical Society of America

1967 – Kimber Genetics Award, National Academy of Sciences

1970 – National Medal of Science, Given By Richard Nixon

1978 – The Louis and Bert Freedman Foundation Award, For Research in Biochemistry

1978 – Lewis S. Rosensteil Award for Distinguished Work in Basic Medical Research

1981 – Thomas Hunt Morgan Medal, Genetics Society of America

1981 – Wolf Prize in Medicine

1981 – Macarthur Foundation Grant

1981 – Albert Lasker Award, for Basic Medical Research

1982 – Louisa Gross Horwitz Prize, Columbia University, for her Research in the Evolution of Genetic Information and the Control of its Expression

1982 – Charles-Léopold Mayer Prize, French Academy of Sciences

1983 – Nobel Prize in Physiology and Medicine, for her Discovery of Mobile Genetic Elements

1993 – Benjamin Franklin Medal, for Distinguished Achievement in the Sciences of the American Philosophical Society

Barbara McClintock was also awarded fourteen Honorary Doctor of Science degrees and an Honorary Doctor of Humane Letters. In 1959 she was elected Fellow of the American Academy of Arts and Sciences, in 1986 she was inducted into the National Women’s Hall of Fame and three years later she was elected as Foreign Member of the Royal Society.

In 2013, Professor Jeffrey Bennetzen founded the Mcclintock Prize for Plant Genetics and Genome Studies.

BIBLIOGRAPHY (BY THE AUTHOR):

McClintock, Barbara. 1929. A cytological and genetical study of triploid maize. Genetics 14 (2): 180—222.

McClintock, Barbara. 1931. The order of the genes C, Sh and Wx in zea mays with reference to a cytologically known point in the chromosome. Proceedings of the National Academy of Sciences of the United States of America 17 (8): 485—491.

URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1076097/pdf/pnas01724-0043.pdf

McClintock, Barbara and Harriet Creighton. 1931. A correlation of cytological and genetical crossing–over in zea mays. Proceedings of the National Academy of Sciences of the United Stated of America 17 (8): 492—497.

URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1076098/pdf/pnas01724-0050.pdf

McClintock, Barbara. 1941. The stability of broken ends of chromosomes in zea mays. Genetics 26 (2): 234—282.

URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1209127/pdf/234.pdf

McClintock, Barbara. 1945. Neurospora. I. Preliminary observations of the chromosomes of neurospora crassa. American Journal of Botany 32 (10): 671—678.

URL: https://profiles.nlm.nih.gov/ps/access/LLBBBC.pdf

McClintock, Barbara. 1961. Some parallels between gene control systems in maize and in bacteria. The American Naturalist 95 (884): 265—277.

McClintock, Barbara, Angel T. Kato Yamakake & Almiro Blumenschein. 1981. Chromosome constitution of races of maize. Its significance in the interpretation of relationships between races and varieties in the Americas. Chapingo, Mexico: Escuela de Nacional de Agricultura, Colegio de Postgraduados.

FURTHER READING:

Bertsch McGrayne, Sharon. 2002. Nobel Prize Women in Science: Their Lives, Struggles and Momentuous Discoveries. Washington DC: Joseph Henry Press.

Comfort, Nathaniel C. 2001. The Tangled Field: Barbara McClintock’s Search for the Patterns of Genetic Control. Harvard University Press.

Culler, J. Heather. 2003. Barbara McClintock. Chelsea House Publishers.

Ferodoff, Nina V. 1987. The Discovery and Characterization of Transposable Elements: The Collected Papers of Barbara McClintock. New York: Garland Publishing Inc.

Fedoroff, Nina V. and David Botstein. 1992. The Dynamic Genome: Barbara McClintock’s Ideas in the Century of Genetics. Cold Spring Harbor Laboratory Press

Fine, Edith Hope. 1998. Barbara McClintock: Nobel Prize Geneticist. Springfield, NJ: Enslow Publications, Inc.

Fox Keller, Evelyn. 1983. A feeling for the Organism: The life and work of Barbara McClintock. San Francisco: W.H. Freeman.

Kathleen, Tracy. 2002. Barbara McClintock: Pioneering Geneticist. Bear, DE: Mitchell Lane Publishers

Koningsburg, E.L. 1988. Barbara McClintock Retrospective. The Nobel Prize annual 1988: 15—27.

Pasachoff, Naomi E. 2006. Barbara McClintock: Genius of genetics. Berkeley Heights, NJ: Enslow Publishers.

Ravindran, Sandeep. 2012. Barbara McClintock and the discovery of jumping genes. PNAS 109 (50):  20198—20199.

Spangenburg, Ray and Diane Kit Moser. 2008.  Barbara McClintock: Pioneering Geneticist. New York: Infobase Publishing.

Swaby, Rachel. 2015. Headstrong: 52 Women Who Changed Science—and the World. New York: Broadway Books.

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