https://www.wikidoc.org/index.php?title=African_clawed_frog&feed=atom&action=historyAfrican clawed frog - Revision history2024-03-28T22:38:37ZRevision history for this page on the wikiMediaWiki 1.40.0https://www.wikidoc.org/index.php?title=African_clawed_frog&diff=709878&oldid=prevWikiBot: Robot: Automated text replacement (-{{WikiDoc Cardiology Network Infobox}} +, -<references /> +{{reflist|2}}, -{{reflist}} +{{reflist|2}})2012-09-04T14:12:18Z<p>Robot: Automated text replacement (-{{WikiDoc Cardiology Network Infobox}} +, -<references /> +{{reflist|2}}, -{{reflist}} +{{reflist|2}})</p>
<p><b>New page</b></p><div>{{Taxobox<br />
| name = African clawed frog<br />
| status = LC<br />
| trend = up<br />
| image = Xenopus_laevis.jpg<br />
| image_width = 240px<br />
| regnum = [[Animal]]ia<br />
| phylum = [[Chordate|Chordata]]<br />
| classis = [[Amphibia]]<br />
| ordo = [[Anura]]<br />
| familia = [[Pipidae]]<br />
| genus = ''[[Xenopus]]''<br />
| species = '''''X. laevis'''''<br />
| binomial = ''Xenopus laevis''<br />
| binomial_authority = [[François Marie Daudin|Daudin]], 1802<br />
}}<br />
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The '''African clawed frog''' (''Xenopus laevis'', also known as '''platanna''') is a species of [[South Africa]]n aquatic [[frog]] of the genus ''[[Xenopus]]''. It is up to 12 cm long with a flattened head and body, but no external ear or tongue. Its name derives from the three short claws on each of its hind feet, which it probably uses to stir up mud to hide it from predators. <br />
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The genus is found throughout much of Europe, North America, South America and Africa.<ref>{{IUCN2006|assessors=Tinsley ''et al''|year=2004|id=58174|title=Xenopus laevis|downloaded=12 May 2006}} Database entry includes a range map and justification for why this species is of least concern</ref><br />
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== Description ==<br />
These frogs are plentiful in ponds and rivers within the southeastern portion of Sub-Saharan Africa. They are aquatic and often a yellowish, grey color. Albino varieties are sold as pets. They reproduce by eggs (see [[Frog#Reproduction of frogs|frog reproduction]]).<br />
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These frogs tend to live 5 to 15 years but some have been recorded to live to be nearly 30 years. They shed every season, and eat their own shed skin.<br />
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Although lacking a vocal sac, the males make a mating call of alternating long and short trills, by contracting the intrinsic laryngeal muscles. Most unusually, females also answer vocally, signaling either acceptance (a rapping sound) or rejection (slow ticking) of the male.<ref>[http://animaldiversity.ummz.umich.edu/site/accounts/information/Xenopus_laevis.html ADW: Xenopus Laevis: Information]</ref><br />
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They also swim very fast, and can eat smaller fish, such as minnows and guppies. When they eat, the food is not actually held down very well, and occasionally, the fish, or bug, can actually escape before being forced back into the mouth by the frog's front hands.<br />
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== Use in genetic research ==<br />
Although ''X. laevis'' does not have the short generation time and genetic simplicity generally desired in genetic [[model organism]]s, it is an important model organism in [[developmental biology]]. ''X. laevis'' takes 1 to 2 years to reach [[sexual maturity]] and, like most of its genus, it is [[tetraploid]]. However, it does have a large and easily manipulable [[embryo]]. The ease of manipulation in [[amphibia]]n embryos has given them an important place in historical and modern developmental biology. A related species, ''[[Xenopus tropicalis]]'', is now being promoted as a more viable model for genetics. [[Roger Wolcott Sperry]] used ''X. laevis'' for his famous experiments describing the development of the visual system. These experiments led to the formulation of the [[Chemoaffinity hypothesis]]. <br />
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[[Image:African Clawed Frog bw.jpg|thumb|left|250px]]<br />
''Xenopus'' [[oocyte]]s provide an important expression system for [[molecular biology]]. By injecting [[DNA]] or [[mRNA]] into the oocyte or developing embryo, scientists can study the protein products in a controlled system. This allows rapid functional expression of manipulated [[DNA]]s (or [[mRNA]]). This is particularly useful in [[electrophysiology]], where the ease of recording from the oocyte makes expression of membrane channels attractive. One challenge of oocyte work is eliminating native proteins that might confound results, such as membrane channels native to the [[oocyte]]. Translation of proteins can be blocked or splicing of pre-mRNA can be modified by injection of [[Morpholino]] antisense oligos into the oocyte (for distribution throughout the embryo) or early embryo (for distribution only into daughter cells of the injected cell).<ref>[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11477685 Comparison of morpholino based translational inhib...[Genesis. 2001&#93; - PubMed Result<!-- Bot generated title -->]</ref><br />
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''X. laevis'' is also notable for its use as the first well-documented method of [[pregnancy]] testing when it was discovered that the [[urine]] from pregnant women induced ''X. laevis'' oocyte production. [[Human chorionic gonadotropin]] (HCG) is a [[hormone]] found in substantial quantities in the urine of pregnant women. Today, commercially available HCG is injected into ''Xenopus'' males and females to induce mating behavior and breed these frogs in captivity at any time of the year.<br />
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== As a pest ==<br />
When African clawed frogs are imported into non-native countries, they have the capacity to wreck entire ecosystems by eating native wildlife such as fish and turtles that have no natural defense against these creatures.{{Fact|date=March 2007}}<br />
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In 2007, these frogs invaded a pond in San Francisco, where much debate exists on how to terminate these creatures and keep them from spreading.<ref>{{cite web | url = http://www.foxnews.com/story/0,2933,258519,00.html | publisher = FoxNews | title = Killer Meat-Eating Frogs Terrorize San Francisco}}</ref><ref>{{cite web | url = http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2007/03/12/BAGLUOJLDE1.DTL | publisher = San Francisco Chronicle | title = The Killer Frogs of Lily Pond:San Francisco poised to checkmate amphibious African predators of Golden Gate Park }}</ref> It is unknown if these frogs entered the San Francisco ecosystem through intentional release or escape into the wild.<br />
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Because these frogs are immune to the fungi ''Batrachochytrium dendrobatidis'' (a chytridomycota) and ''B. dendrobatidis'' has been traced back to the habitat of Xenopus laevis in Africa, many scholars believe it is the source of the worldwide frog population crash. Due to its extensive use in obstetrics and research, it appears Xenopus laevis has carried ''B. dendrobatidis'' with it out of Africa to all over the world, causing chytridomycosis and eventually death in native frogs naïve to the fungi.<br />
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==References==<br />
{{reflist|2}}<br />
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== External links == <br />
* [http://www.xenbase.org/ Xenbase] A ''Xenopus laevis'' and ''X. tropicalis'' web resource.<br />
* [http://www-cbd.ups-tlse.fr/organismes/nieuwkoop/nieuwkoop.html The stages of ''Xenopus'' embryonic development] Adapted from P.D. Nieuwkoop and J. Faber's Normal Table of ''Xenopus laevis'' (Daudin).<br />
* [http://reptilopolis.kanak.fr/autres-Anoures-f14/Xenopus-laevisDaudin1802-t186.htm Xenopus laevis] Une fiche d'élevage sur les Xénopes en français.<br />
*[http://www.cshprotocols.org/cgi/content/full/2007/12/pdb.prot4749 Xenopus laevis Keller Explants]<br />
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[[Category:Pipidae]]<br />
[[Category:Model organisms]]<br />
[[Category:Amphibians of Africa]]<br />
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