Editing Sea urchin (section)

=== Science ===
Sea urchins are traditional [[model organisms]] in [[developmental biology]]. This use originated in the 1800s, when their embryonic development became easily viewed by microscopy. The transparency of the urchin's eggs enabled them to be used to observe that [[sperm]] cells actually fertilize [[ova]].<ref>{{cite web |url=http://www.exploratorium.edu/imaging-station/research/urchin/story_urchin1.php |title=Insight from the Sea Urchin |work=Microscope Imaging Station |publisher=Exploratorium |access-date=2018-03-07 |archive-url=https://web.archive.org/web/20170312223637/https://www.exploratorium.edu/imaging-station/research/urchin/story_urchin1.php |archive-date=2017-03-12}}</ref> They continue to be used for embryonic studies, as [[prenatal development]] continues to seek testing for fatal diseases. Sea urchins are being used in longevity studies for comparison between the young and old of the species, particularly for their ability to regenerate tissue as needed.<ref>{{Cite journal |last1=Bodnar |first1=Andrea G. |last2=Coffman |first2=James A. |date=2016-08-01 |title=Maintenance of somatic tissue regeneration with age in short- and long-lived species of sea urchins |journal=Aging Cell |volume=15 |issue=4 |pages=778–787 |doi=10.1111/acel.12487 |issn=1474-9726 |pmc=4933669 |pmid=27095483}}</ref> Scientists at the [[University of St Andrews]] have discovered a genetic sequence, the '2A' region, in sea urchins previously thought to have belonged only to viruses like [[foot-and-mouth disease virus]].<ref>{{Cite journal | title='2A-Like' Signal Sequences Mediating Translational Recoding: A Novel Form of Dual Protein Targeting | pmc=4981915 | pmid=27161495 | doi=10.1111/tra.12411 | volume=17 | issue=8 | year=2016 | pages=923–39 | last1=Roulston | first1=C. | last2=Luke | first2=G.A. | last3=de Felipe | first3=P. | last4=Ruan | first4=L. | last5=Cope | first5=J. | last6=Nicholson | first6=J. | last7=Sukhodub | first7=A. | last8=Tilsner | first8=J. | last9=Ryan | first9=M.D. | journal=Traffic | url=https://research-repository.st-andrews.ac.uk/bitstream/10023/8924/1/Roulston_2016_Traffic_2A_Like_CCBY_FinalPublishedVersion.pdf | access-date=2018-10-24 | archive-date=2024-08-25 | archive-url=https://web.archive.org/web/20240825043716/https://research-repository.st-andrews.ac.uk/bitstream/10023/8924/1/Roulston_2016_Traffic_2A_Like_CCBY_FinalPublishedVersion.pdf | url-status=live }}</ref> More recently, [[Eric H. Davidson]] and [[Roy John Britten]] argued for the use of urchins as a model organism due to their easy availability, high fecundity, and long lifespan. Beyond [[embryology]], urchins provide an opportunity to research [[cis-regulatory element]]s.<ref>{{Cite web |url=http://sugp.caltech.edu/SUGP/intro/index.php |title=Sea Urchin Genome Project |website=sugp.caltech.edu |access-date=2016-12-05 |archive-url=https://web.archive.org/web/20161220061841/http://sugp.caltech.edu/SUGP/intro/index.php |archive-date=2016-12-20 |url-status=dead }}</ref> Oceanography has taken an interest in monitoring the health of urchins and their populations as a way to assess overall [[ocean acidification]],<ref>{{Cite web |url=http://news.stanford.edu/pr/2013/pr-urchins-ocean-acidity-040813.html |title=Stanford seeks sea urchin's secret to surviving ocean acidification {{!}} Stanford News Release |website=news.stanford.edu |access-date=2016-12-05 |date=2013-04-08 |archive-date=2016-12-20 |archive-url=https://web.archive.org/web/20161220065330/http://news.stanford.edu/pr/2013/pr-urchins-ocean-acidity-040813.html |url-status=dead }}</ref> temperatures, and ecological impacts.

The organism's evolutionary placement and unique embryology with five-fold symmetry were the major arguments in the proposal to seek the sequencing of its [[genome]]. Importantly, urchins act as the closest living relative to chordates and thus are of interest for the light they can shed on the evolution of [[vertebrate]]s.<ref name="ncbi.nlm.nih.gov">{{Cite journal |date=2006-11-10 |title=The Genome of the Sea Urchin Strongylocentrotus purpuratus |journal=Science |volume=314 |issue=5801 |pages=941–952 |doi=10.1126/science.1133609 |pmc=3159423 |pmid=17095691 | last1 = Sodergren | first1 = E | last2 = Weinstock | first2 = GM | last3 = Davidson | first3 = EH |display-authors=etal |bibcode=2006Sci...314..941S }}</ref> The genome of ''[[Strongylocentrotus purpuratus]]'' was completed in 2006 and established homology between sea urchin and vertebrate [[immune system]]-related genes. Sea urchins code for at least 222 [[Toll-like receptor]] genes and over 200 genes related to the [[Nod-like-receptor]] family found in vertebrates.<ref>{{cite journal |last1=Rast |first1=JP |last2=Smith |first2=LC |last3=Loza-Coll |first3=M |last4=Hibino |first4=T |last5=Litman |first5=GW |title=Genomic Insights into the Immune System of the Sea Urchin |journal=Science |volume=314 |issue=5801 |pages=952–6 |year=2006 |pmid=17095692 |doi=10.1126/science.1134301|bibcode = 2006Sci...314..952R |pmc=3707132 }}</ref> This increases its usefulness as a valuable model organism for studying the [[evolution]] of [[innate immunity]]. The sequencing also revealed that while some genes were thought to be limited to vertebrates, there were also innovations that have previously never been seen outside the chordate classification, such as immune transcription factors [[PU.1]] and [[SPIB]].<ref name="ncbi.nlm.nih.gov" />