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Examples of structural inheritance include the propagation of [[prion]]s, the infectious proteins of diseases such as [[scrapie]] (in sheep and goats), [[bovine spongiform encephalopathy]] ('mad cow disease') and [[Creutzfeld-Jakob disease]] (although the protein-only hypothesis of prion transmission has been considered contentious until recently.)<ref name="pmid15272271">{{cite journal | author = Soto C, Castilla J | title = The controversial protein-only hypothesis of prion propagation | journal = Nat. Med. | volume = 10 Suppl | issue = 7| pages = S63–7 | year = 2004 | month = July | pmid = 15272271 | doi = 10.1038/nm1069 }}</ref> Prions based on heritable protein structure also exist in [[yeast]].<ref name="pmid7569955">{{cite journal | author = Masison DC, Wickner RB | title = Prion-inducing ___domain of yeast Ure2p and protease resistance of Ure2p in prion-containing cells | journal = Science | volume = 270 | issue = 5233 | pages = 93–5 | year = 1995 | month = October | pmid = 7569955 | doi = 10.1016/0168-9525(96)10045-7 }}</ref><ref name="pmid8973157">{{cite journal | author = Tuite MF, Lindquist SL | title = Maintenance and inheritance of yeast prions | journal = Trends Genet. | volume = 12 | issue = 11 | pages = 467–71 | year = 1996 | month = November | pmid = 8973157 | doi = 10.1016/0168-9525(96)10045-7 }}</ref><ref name="pmid11573346">{{cite journal | author = Serio TR, Cashikar AG, Kowal AS, Sawicki GJ, Lindquist SL | title = Self-perpetuating changes in Sup35 protein conformation as a mechanism of heredity in yeast | journal = Biochem. Soc. Symp. | volume = | issue = 68 | pages = 35–43 | year = 2001 | pmid = 11573346 | doi = }}</ref> Structural inheritance has also been seen in the orientation of [[cilium|cilia]] in protozoans such as ''[[Paramecium]]''<ref name="pmid14294056">{{cite journal | author = Beisson J, Sonneborn TM | title = Cytoplasmic inheritance of the organization of the cell cortex in paramecium aurelia | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 53 | issue = 2| pages = 275–82 | year = 1965 | month = February | pmid = 14294056 | pmc = 219507 | doi = 10.1073/pnas.53.2.275 }}</ref> and ''[[Tetrahymena]]'',<ref name="Nelsen89">{{cite journal | author = Nelsen EM, Frankel J, Jenkins LM | title = Non-genic inheritance of cellular handedness | journal = Development | volume = 105 | issue = 3 | pages = 447–56 | year = 1989 | month = March | pmid = 2612360 | doi = | url = http://dev.biologists.org/content/105/3/447.full.pdf }}</ref> and 'handedness' of the spiral of the cell in ''Tetrahymena'',<ref name=Nelsen89/> and shells of snails. Some [[organelle]]s also have structural inheritance, such as the [[centriole]], and the [[cell (biology)|cell]] itself (defined by the [[plasma membrane]]) may also be an example of structural inheritance. To emphasize the difference of the molecular mechanism of structural inheritance from the canonical Watson-Crick base-pairing mechanism of transmission of genetic information, the term 'Epigenetic templating' was introduced.<ref name="pmid16809769">{{cite journal | author = Viens A, Mechold U, Brouillard F, Gilbert C, Leclerc P, Ogryzko V | title = Analysis of human histone H2AZ deposition in vivo argues against its direct role in epigenetic templating mechanisms | journal = Mol. Cell. Biol. | volume = 26 | issue = 14 | pages = 5325–35 | year = 2006 | month = July | pmid = 16809769 | pmc = 1592707 | doi = 10.1128/MCB.00584-06 }}</ref><ref name="pmid18419815">{{cite journal | author = Ogryzko VV | title = Erwin Schroedinger, Francis Crick and epigenetic stability | journal = Biol. Direct | volume = 3 | issue = | pages = 15 | year = 2008 | pmid = 18419815 | pmc = 2413215 | doi = 10.1186/1745-6150-3-15 }}</ref>
==History==
'''Cortical Inheritance''' or [[structural inheritance]] was discovered by [[Tracy Sonneborn]], and other researchers, during his study on [[protozoa]] in the late 1930s. Sonneborn demonstrated during his research on [[Paramecium]] that the structure of the cortex was not dependent on genes, or the liquid cytoplasm, but in the cortical structure of the surface of the ciliates. Preexisting cell surface structures provided a template that was passed on for many generations.<ref name="pmid16554410">{{cite journal | author = Preer JR | title = Sonneborn and the cytoplasm | journal = Genetics | volume = 172 | issue = 3 | pages = 1373–7 | year = 2006 | month = March | pmid = 16554410 | pmc = 1456306 | doi = | url = | issn = }}</ref>
John R. Preer, Jr., following up on Sonneborn's work, says, "The arrangement of surface structures is inherited, but how is not known, Macronuclei pass on many of their characteristics to new macronuclei, by an unknown and mysterious mechanism."<ref name="pmid9071578">{{cite journal | author = Preer JR | title = Whatever happened to paramecium genetics? | journal = Genetics | volume = 145 | issue = 2 | pages = 217–25 | year = 1997 | month = February | pmid = 9071578 | pmc = 1207789 | doi = | url = | issn = }}</ref>
Other researchers have come to the conclusion that "the phenomena of cortical inheritance (and related nongenic, epigenetic processes) remind us that the fundamental reproductive unit of life is not a nucleic acid molecule, but the remarkably versatile, intact, living cell."<ref>{{cite web|url=http://science.jrank.org/pages/48371/Cortical-Inheritance.html |title=Cortical Inheritance – Paramecium, Tetrahymena:, Teutophrys, Dileptus, Paramecium:, Pattern Formation: Ciliate Studies and Models – Cell, Cells, Structures, Prion, Genetic, and Information |publisher=Science.jrank.org |date= |accessdate=2011-06-30}}</ref>
==In Popular Culture==
An article in Newsweek mentions research that shows that "Some water fleas sport a spiny helmet that deters predators; others, with identical DNA sequences, have bare heads. What differs between the two is not their genes but their mothers' experiences. If mom had a run-in with predators, her offspring have helmets, an effect one wag called "bite the mother, fight the daughter." If mom lived her life unthreatened, her offspring have no helmets. Same DNA, different traits. Somehow, the experience of the mother, not only her DNA sequences, has been transmitted to her offspring."<ref>{{cite web|author=by Sharon BegleyJanuary 17, 2009 |url=http://www.newsweek.com/2009/01/16/the-sins-of-the-fathers-take-2.html |title=Begley: Was Darwin Wrong About Evolution? |publisher=Newsweek |date=2009-01-17 |accessdate=2011-06-30}}</ref>
Various additional examples of structural inheritance are presented in the recent book ''[[Origination of Organismal Form]]''.
== References ==
{{reflist|
== Further reading ==
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