Editing Tobacco mosaic virus (section)

== History ==
In 1886, [[Adolf Mayer]] first described the tobacco mosaic disease that could be transferred between plants, similar to [[bacteria]]l infections.<ref>{{cite journal | vauthors = Mayer A | name-list-style = vanc | title = Über die Mosaikkrankheit des Tabaks. | journal = Die Landwirtschaftliche Versuchs-stationen | volume = 32 | pages = 451–467 | year = 1886 | language = de}} Translated into English in {{cite journal | title = Concerning the mosaic disease of tobacco | veditors = Johnson J | date = 1942 | url = https://www.apsnet.org/edcenter/apsnetfeatures/Documents/2008/Mayer1886.pdf | journal = Phytopathological Classics | location = St. Paul, Minnesota | publisher = American Phytopathological Society | volume = 7 | pages = 11–24 }}</ref><ref name="zaitlin">{{cite book| vauthors = Zaitlin M |author-link=Milton Zaitlin |  veditors  = Kung SD, Yang SF | title = Discoveries in Plant Biology| year = 1998| publisher = World Publishing Co.| location  = Hong Kong| isbn = 978-981-02-1313-8| pages = 105–110| chapter = The Discovery of the Causal Agent of the Tobacco Mosaic Disease| chapter-url = https://www.apsnet.org/edcenter/apsnetfeatures/Documents/1998/ZaitlinDiscoveryCausalAgentTobaccoMosaicVirus.pdf }}</ref> In 1892, [[Dmitri Ivanovsky]] gave the first concrete evidence for the existence of a non-bacterial infectious agent, showing that infected sap remained infectious even after filtering through the finest [[Chamberland filter]]s.<ref name="zaitlin" /><ref>{{cite journal | vauthors = Iwanowski D | title = Über die Mosaikkrankheit der Tabakspflanze | journal = Bulletin Scientifique Publié Par l'Académie Impériale des Sciences de Saint-Pétersbourg / Nouvelle Serie III | volume = 35 | pages = 67–70 | year = 1892 | language = de, ru}} Translated into English in {{cite journal | title = Concerning the mosaic disease of the tobacco plant | veditors = Johnson J | date = 1942 | url = | journal = Phytopathological Classics | location = St. Paul, Minnesota | publisher = American Phytopathological Society | volume = 7 | pages = 27–30 }}</ref> Later, in 1903, Ivanovsky published a paper describing abnormal crystal intracellular inclusions in the host cells of the affected tobacco plants and argued the connection between these inclusions and the infectious agent.<ref>{{cite journal | vauthors = Iwanowski D | title = Über die Mosaikkrankheit der Tabakspflanze | journal = Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz |jstor=43221892| volume = 13 | issue = 1 | pages = 1–41 | year = 1903 | language = de}}</ref> However, Ivanovsky remained rather convinced, despite repeated failures to produce evidence, that the causal agent was an unculturable bacterium, too small to be retained on the employed Chamberland filters and to be detected in the light microscope. In 1898, [[Martinus Beijerinck]] independently replicated Ivanovsky's filtration experiments and then showed that the infectious agent was able to reproduce and multiply in the host cells of the tobacco plant.<ref name="zaitlin" /><ref>{{cite journal | vauthors = Beijerinck MW | title = Über ein Contagium vivum fluidum als Ursache der Fleckenkrankheit der Tabaksblätter|url=https://www.dwc.knaw.nl/DL/publications/PU00011860.pdf | journal = Verhandelingen der Koninklijke Akademie van Wetenschappen te Amsterdam | volume = 65 | pages = 1–22 | year = 1898 | language = de}} Translated into English in {{cite journal | title = Contagium vivum fluidum as the cause of spot disease in tobacco leaves | veditors = Johnson J | date = 1942 | url = | journal = Phytopathological Classics | location = St. Paul, Minnesota | publisher = American Phytopathological Society | volume = 7 | pages = 33–52 }}</ref> Beijerinck adopted the term of "[[wiktionary:virus#Etymology|virus]]" to indicate that the causal agent of tobacco mosaic disease was of non-bacterial nature. Tobacco mosaic virus was the first virus to be [[Protein crystallization|crystallized.]] It exhibits [[liquid crystal]] phases above a critical density.<ref>{{Cite journal |last=Bawden |first=F. C. |last2=Pirie |first2=N. W. |last3=Bernal |first3=J. D. |last4=Fankuchen |first4=I. |date=1936-12-01 |title=Liquid Crystalline Substances from Virus-infected Plants |url=https://ui.adsabs.harvard.edu/abs/1936Natur.138.1051B/abstract |journal=Nature |volume=138 |pages=1051–1052 |doi=10.1038/1381051a0 |issn=0028-0836}}</ref> It was achieved by [[Wendell Meredith Stanley]] in 1935 who also showed that TMV remains active even after crystallization.<ref name="zaitlin" /> For his work, he was awarded 1/4 of the [[Nobel Prize in Chemistry]] in 1946,<ref>{{cite web|url=http://nobelprize.org/nobel_prizes/chemistry/laureates/1946/stanley-bio.html|title=Wendell M. Stanley – Biographical|website=nobelprize.org}}</ref><ref>{{Cite web|url=https://www.nobelprize.org/prizes/chemistry/1946/summary/|title=The Nobel Prize in Chemistry 1946|website=NobelPrize.org|access-date=2019-12-03}}</ref> even though it was later shown some of his conclusions (in particular, that the crystals were pure protein, and assembled by [[autocatalysis]]) were incorrect.<ref>{{cite journal | vauthors = Kay LE | title = W. M. Stanley's crystallization of the tobacco mosaic virus, 1930–1940 | journal = Isis; an International Review Devoted to the History of Science and Its Cultural Influences | volume = 77 | issue = 288 | pages = 450–72 | date = September 1986 | pmid = 3533840 | doi = 10.1086/354205 | jstor = 231608 | s2cid = 37003363 }}</ref> The first electron microscopical images of TMV were made in 1939 by [[Gustav Kausche]], [[Edgar Pfankuch]] and [[Helmut Ruska]] – the brother of Nobel Prize winner [[Ernst Ruska]].<ref>{{cite journal |vauthors=Kausche GA, Pfankuch E, Ruska H |s2cid=206795712 |title=Die Sichtbarmachung von pflanzlichem Virus im Übermikroskop  |journal=Naturwissenschaften |volume=27 |issue=18 |pages=292–9 |date=May 1939 |doi=10.1007/BF01493353 |bibcode=1939NW.....27..292K  }}</ref> In 1955, [[Heinz Fraenkel-Conrat]] and [[Robley Williams]] showed that purified TMV RNA and its [[capsid]] (coat) protein assemble by themselves to functional viruses, indicating that this is the most stable structure (the one with the lowest free energy).
The [[X-ray crystallography|crystallographer]] [[Rosalind Franklin]] worked for Stanley for about a month at [[University of California, Berkeley|Berkeley]], and later designed and built a model of TMV for the [[1958 World's Fair]] at [[Brussels]]. In 1958, she speculated that the virus was hollow, not solid, and hypothesized that the [[RNA]] of TMV is single-stranded.<ref>{{cite book| vauthors = Maddox B |title=Rosalind Franklin, the Dark Lady of DNA|url=https://archive.org/details/rosalindfranklin00madd|url-access=registration|year=2002|publisher=Harper Collins|isbn=978-0-06-018407-0}}</ref>  This conjecture was proven to be correct after her death and is now known to be the + strand.<ref>{{cite web | vauthors = Zaitlin M | date = 1984 | veditors = Brunt AA, Crabtree K, Dallwitz MJ, Gibbs AJ, Watson L, Zurcher EJ | url = http://www.agls.uidaho.edu/ebi/vdie/descr803.htm | title =Tobacco mosaic ''tobamovirus'' | work = Plant Viruses Online: Descriptions and Lists from the VIDE Database | archive-url = https://web.archive.org/web/20091001005452/http://www.agls.uidaho.edu/ebi/vdie/descr803.htm | archive-date = 2009-10-01 }}</ref> The investigations of tobacco mosaic disease and subsequent discovery of its viral nature were instrumental in the establishment of the general concepts of [[virology]].<ref name="zaitlin" />