Thomas Hunt Morgan: Difference between revisions
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==Columbia University== |
==Columbia University== |
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In 1903 Morgan was offered the United States first professorship in experimental zoology at [[Columbia University]] by Edmund Beecher Wilson, in the same year he became engaged and married former student Lilian Vaughan Sampson. The couple moved to [[New York City|New York]] |
In 1903 Morgan was offered the United States first professorship in experimental zoology at [[Columbia University]] by Edmund Beecher Wilson, in the same year he became engaged and married former student Lilian Vaughan Sampson. The couple moved to [[New York City|New York]] and had four children. Morgan was soon engaged in research in the newly rediscovered field of genetics. In 1900 three scientists, [[Carl Correns]], [[Erich von Tschermak]] and [[Hugo De Vries]] had rediscovered the work of [[Gregor Mendel]] and DeVries had proposed that new species are created by mutation. He was quite skeptical of [[Gregor Mendel]]'s laws of heredity, which had been recently stirred up with the emerging [[Darwinian]] and [[Lamarckian]] theories of evolution. Morgan dismissed both of these evolutionary theories, and was actually seeking to prove [[Hugo De Vries]]' [[mutation theory]] with his ''Dropophila'' experiments. |
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Following [[William E. Castle]], he started working on the [[Drosophila embryogenesis|embryonic development]] of common fruit fly ''[[Drosophila melanogaster]]''. Working with [[Fernandus Payne]] he mutated ''Drosophila'' with [[X-rays]] and began cross-breeding experiments, but had no success for two years. Finally in 1910, |
Following [[William E. Castle]], he started working on the [[Drosophila embryogenesis|embryonic development]] of common fruit fly ''[[Drosophila melanogaster]]''. Working with [[Fernandus Payne]] he mutated ''Drosophila'' with [[X-rays]] and began cross-breeding experiments, but had no visible success for two years. Castle had also had difficulty identifying mutations in ''Drosophila'', hardly unusual given the flies tiny size. Finally in 1910, Morgan noticed a white-eyed [[mutant]] male among the red-eyed [[wild type]]s. He bred this white-eyed fly with a red-eyed female. Their progeny were all red-eyed, suggesting that the white eye trait was recessive. Morgan thus named the gene ''white'', starting the tradition of naming genes after their mutant [[allele]]. As Morgan continued to cross-breed the mutants back to one another, he noticed that only males displayed the white-eyed trait. Morgan also discovered a pink eyed mutant that showed a different pattern of inheritence. He wrote a paper which was published in ''[[Science (journal)|Science]]'' in 1911, he concluded that (1) some traits were [[sex-linked]], (2) the trait was probably carried on one of the [[sex chromosome]]s, and (3) other genes were probably carried on specific chromosomes as well. |
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Morgan and his students became more successful at finding mutant flies and counted the mutant characteristics of thousands of fruit flies and studied their inheritance. The observation of a miniture wing mutant which was also on the sex chromosome but sometimes sorted independently to the white eye mutation, led Morgan to the idea of [[genetic linkage]]. Morgan proposed that the amount of crossing over between linked genes differs and that crossover frequency might indicate the distance separating genes on the chromosome, later English geneticist [[J. B. S. Haldane]] suggested that the unit of measurement be called the morgan. Morgan's student [[Alfred Sturtevant]] developed the first [[genetic map]] in 1913. In 1915 Morgan, Sturtevant, [[Calvin Bridges]] and [[H. J. Muller]] wrote the seminal book ''[[The Mechanism of Mendelian Inheritance]]''. Geneticist [[Curt Stern]] called the book "the fundamental textbook of the new genetics" and [[C. H. Waddington]] noted that "Morgan's theory of the chnomosome represents a great leap of imagination comparable with Galileo or Newton". |
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Following the books publication Morgan was established as the twentieth centuries Mendel. John Hopkins awarded Morgan an honarary LL.D. and the University of Kentucky awarded him an honary Ph.D. He was elected a member of the [[National Academy of Sciences]] and made a foreign member of the Royal Society. His Fly Room at Coloumbia became world famous and he found it easy to attract funding and visiting academics. In 1927 after 25 years at Columbia, and nearing the age of retirement he recieved an offer to establish a school of biology in California. |
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==California Institute of Technology== |
==California Institute of Technology== |
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Revision as of 08:08, 8 January 2006
Thomas Hunt Morgan (September 25, 1866 – December 4, 1945) was an American geneticist. His research focussed on the natural history, zoology, and macromutation in the fruit fly Drosophila. His most important contributions to science were in the development of the modern science of genetics, as he was the first person to demonstrate the genes are carried on chromosomes and are the mechanical basis of heredity. When he was awarded the Nobel Prize in Physiology or Medicine in 1933 he was the first person awarded the Prize for genetics, specifically for demonstrating hereditary transmission mechanisms in Drosophilia.
During his distinguished career Morgan wrote 22 book and 370 scientific papers, and as a result of his work Drosophila became one of the major model organisms in contemporary genetics.
Early life
Morgan was born in Lexington, Kentucky to Charlton Hunt Morgan and Ellen Key Howard. His family was part of a long line of Southern aristocracy, his father was a nephew of Confederate General John Hunt Morgan and his great-grandfather John Wesley Hunt had been the first millionaire west of the Allegheny Mountains. He was also a great-grandson of Francis Scott Key author of the "Star Spangled Banner". However following the civil war the family had fallen on harder times with the loss of civil and property rights for those who aided the Confederacy, his father also had difficulty finding work in politics and spent much of his time coordinating veterans reunions.
When Morgan turned 14 he enrolled at the State College of Kentucky (now the University of Kentucky), he choose to study science and particularly enjoyed natural history, and worked with the federal geological survey in his summers. He graduated in in 1886 and was the only student to graduate with a bachelor of science, he was also valedictorian. He choose to undertake graduate studies at Johns Hopkins University, Hopkins was one of the few universities in the United States at that time which taught biology extensively. After two years of experimental work and several publications Morgan was eligible to receive a master of science from the State College of Kentucky in 1888, the College required two years study at another institution and an examination by the College Faculty. The College offered Morgan a full professorship, however he choose to stay at Johns Hopkins and was awarded a relatively large fellowship to do so.
Morgan completed his experimental work at Woods Hole, Massachusetts at the Marine Biology Laboratory. He studied the embryology of sea spiders to determine their phylogenic relationship with spiders and crustaceans. He concluded that with respect to embryology they were more closely related to spiders than crustaceans. Based on the publication of this work Morgan was awarded his Ph.D. from Johns Hopkins in 1890, he was also awarded the Bruce Fellowship in Research. With the Fellowship he was able to travel to Jamaica, the Bahamas and to Europe to conduct further research.
Bryn Mawr
Morgan was appointed the associate professor at Johns Hopkins sister school Bryn Mawr replacing his colleague Edmund Wilson in 1891. He lectured in biology 5 days a week, giving two lectures a day. He frequently included his own recent research in his lectures, and although he was an enthusiastic teacher his true interests were in the laboratory. During the first few years at Bryn Mawr he produced descriptive studies of sea acorns, ascadian worms and frogs.
In 1894 he was granted a years absence to conduct research in the laboratories of Stazione Zoologica in Naples. At the laboratory in Naples he worked with German biologist Hans Driesch whos research in the experimental study of development piqued Morgans interest. At the time there was considerable scientific debate over the question of how an embryo formed, one group of scientists believed that the cells were predestined (preformed) to become frogs, the other group thought that development was due to epigenetic factors where interactions between the protoplasam and the nucleus of the egg and the environment could affect development. Morgan was in the later camp, and successfully demonstrated that a daughter cell from a white fish embryo could develop normally into a complete fish confirming Drieschs earlier experiments. He also showed that sea urchin eggs could be induced to divide without fertilization by adding magnesium chloride, work which was continued by Jacques Loeb who became well known for creating fatherless frogs using the method.
Morgan returned to Bryn Mawr in 1895 and was promoted to full professor. He wrote his first book The Development of the Frog's Egg and it was published in 1897. He began a series of studies on different organisms ability to regenerate. He looked at grafting and regeneration in tadpoles, fish and earthworms and in 1901 this work was published as Regeneration.
Columbia University
In 1903 Morgan was offered the United States first professorship in experimental zoology at Columbia University by Edmund Beecher Wilson, in the same year he became engaged and married former student Lilian Vaughan Sampson. The couple moved to New York and had four children. Morgan was soon engaged in research in the newly rediscovered field of genetics. In 1900 three scientists, Carl Correns, Erich von Tschermak and Hugo De Vries had rediscovered the work of Gregor Mendel and DeVries had proposed that new species are created by mutation. He was quite skeptical of Gregor Mendel's laws of heredity, which had been recently stirred up with the emerging Darwinian and Lamarckian theories of evolution. Morgan dismissed both of these evolutionary theories, and was actually seeking to prove Hugo De Vries' mutation theory with his Dropophila experiments.
Following William E. Castle, he started working on the embryonic development of common fruit fly Drosophila melanogaster. Working with Fernandus Payne he mutated Drosophila with X-rays and began cross-breeding experiments, but had no visible success for two years. Castle had also had difficulty identifying mutations in Drosophila, hardly unusual given the flies tiny size. Finally in 1910, Morgan noticed a white-eyed mutant male among the red-eyed wild types. He bred this white-eyed fly with a red-eyed female. Their progeny were all red-eyed, suggesting that the white eye trait was recessive. Morgan thus named the gene white, starting the tradition of naming genes after their mutant allele. As Morgan continued to cross-breed the mutants back to one another, he noticed that only males displayed the white-eyed trait. Morgan also discovered a pink eyed mutant that showed a different pattern of inheritence. He wrote a paper which was published in Science in 1911, he concluded that (1) some traits were sex-linked, (2) the trait was probably carried on one of the sex chromosomes, and (3) other genes were probably carried on specific chromosomes as well.
Morgan and his students became more successful at finding mutant flies and counted the mutant characteristics of thousands of fruit flies and studied their inheritance. The observation of a miniture wing mutant which was also on the sex chromosome but sometimes sorted independently to the white eye mutation, led Morgan to the idea of genetic linkage. Morgan proposed that the amount of crossing over between linked genes differs and that crossover frequency might indicate the distance separating genes on the chromosome, later English geneticist J. B. S. Haldane suggested that the unit of measurement be called the morgan. Morgan's student Alfred Sturtevant developed the first genetic map in 1913. In 1915 Morgan, Sturtevant, Calvin Bridges and H. J. Muller wrote the seminal book The Mechanism of Mendelian Inheritance. Geneticist Curt Stern called the book "the fundamental textbook of the new genetics" and C. H. Waddington noted that "Morgan's theory of the chnomosome represents a great leap of imagination comparable with Galileo or Newton".
Following the books publication Morgan was established as the twentieth centuries Mendel. John Hopkins awarded Morgan an honarary LL.D. and the University of Kentucky awarded him an honary Ph.D. He was elected a member of the National Academy of Sciences and made a foreign member of the Royal Society. His Fly Room at Coloumbia became world famous and he found it easy to attract funding and visiting academics. In 1927 after 25 years at Columbia, and nearing the age of retirement he recieved an offer to establish a school of biology in California.
California Institute of Technology
Morgan moved to the California Institute of Technology in 1928. Morgan died in Pasadena, California.
Legacy
Morgan left an important legacy in genetics. Some of Morgan's students from Columbia and Caltech went on to win their own Nobel Prizes, including George Wells Beadle, Edward B. Lewis and Hermann Joseph Muller. In Morgan's honor, the Genetics Society of America annually awards the Thomas Hunt Morgan Medal to one of its members who has made a significant contribution to the science of genetics. Nobel prize winner Eric Kandel has written of Morgan, "Much as Darwin's insights into the evolution of animal species first gave coherence to nineteenth-century biology as a descriptive science, Morgan's findings about genes and their location on chromosomes helped transform biology into an experimental science." The centimorgan, a unit of recombinant frequency used in gene mapping, was named in his honor.
The Thomas Hunt Morgan School of Biological Sciences at the University of Kentucky is named for Morgan.
References
- Shine, I. and Wrobel, S. 1976. Thomas Hunt Morgan: Pioneer of Genetics. The University Press of Kentucky ISBN 081310095X