Editing Transposable element (section)

== Discovery by Barbara McClintock ==

[[Barbara McClintock]] discovered the first TEs in [[maize]] (''Zea mays'') at the [[Cold Spring Harbor Laboratory]] in New York. McClintock was experimenting with maize plants that had broken chromosomes.<ref name="McGrayne165">{{cite book | vauthors = McGrayne SB |title=Nobel Prize Women in Science: Their Lives, Struggles, and Momentous Discoveries |url=https://books.google.com/books?id=e7NaAAAAYAAJ |year=1998 |publisher=Carol Publishing |isbn=978-0-9702256-0-3 |edition=2nd |page=165}}</ref>

In the winter of 1944–1945, McClintock planted corn kernels that were self-pollinated, meaning that the silk ([[Style (botany)|style]]) of the flower received pollen from its own [[anther]].<ref name="McGrayne165" /> These kernels came from a long line of plants that had been self-pollinated, causing broken arms on the end of their ninth chromosomes.<ref name="McGrayne165" /> As the maize plants began to grow, McClintock noted unusual color patterns on the leaves.<ref name="McGrayne165" /> For example, one leaf had two albino patches of almost identical size, located side by side on the leaf.<ref name="McGrayne165" /> McClintock hypothesized that during cell division certain cells lost genetic material, while others gained what they had lost.<ref name="McGrayne166">{{harnvb|McGrayne|1998|p=166}}</ref> However, when comparing the chromosomes of the current generation of plants with the parent generation, she found certain parts of the chromosome had switched position.<ref name="McGrayne166" /> This refuted the popular genetic theory of the time that genes were fixed in their position on a chromosome. McClintock found that genes could not only move but they could also be turned on or off due to certain environmental conditions or during different stages of cell development.<ref name="McGrayne166" />

McClintock also showed that gene mutations could be reversed.<ref name="McGrayne167">{{harnvb|McGrayne|1998|p=167}}</ref> She presented her report on her findings in 1951, and published an article on her discoveries in ''Genetics'' in November 1953 entitled "Induction of Instability at Selected Loci in Maize".<ref>{{cite journal | vauthors = McClintock B | title = Induction of Instability at Selected Loci in Maize | journal = Genetics | volume = 38 | issue = 6 | pages = 579–99 | date = November 1953 | doi = 10.1093/genetics/38.6.579 | pmid = 17247459 | pmc = 1209627 | url = http://www.genetics.org/cgi/pmidlookup?view=long&pmid=17247459 }}</ref>

At the 1951 Cold Spring Harbor Symposium where she first publicized her findings, her talk was met with silence.<ref>{{cite journal| title = Proceedings of the National Academy of Sciences Dec 2012, 109 (50) 20198-20199; DOI: 10.1073/pnas.1219372109| year = 2012| doi = 10.1073/pnas.1219372109| pmid = 23236127| last1 = Ravindran| first1 = S.| journal = Proceedings of the National Academy of Sciences of the United States of America| volume = 109| issue = 50| pages = 20198–20199| pmc = 3528533| doi-access = free}}</ref> Her work was largely dismissed and ignored until the late 1960s–1970s when, after TEs were found in bacteria, it was rediscovered.<ref>{{cite book | vauthors = Des Jardins J |title=The Madame Curie Complex: The Hidden History of Women in Science |url=https://books.google.com/books?id=HULGDNDSenYC&pg=PA246 |year=2010 |publisher=Feminist Press at CUNY |isbn=978-1-55861-655-4 |page=246}}</ref> She was awarded a [[List of Nobel laureates in Physiology or Medicine|Nobel Prize in Physiology or Medicine]] in 1983 for her discovery of TEs, more than thirty years after her initial research.<ref>{{cite book | veditors = Fedoroff N, Botstein D |title=The Dynamic Genome: Barbara McClintock's Ideas in the Century of Genetics |url=https://books.google.com/books?id=BF1xfIGd0b4C&pg=PA2 |date=1 January 1992 |publisher=Cold Spring Harbor Laboratory Press |isbn=978-0-87969-422-7 |page=2}}</ref>