View source for Mucron

{{short description|Attachment organelle of archigregarine cells}}
A '''mucron''' is an attachment [[organelle]] found in [[Archigregarinorida|archigregarine]]s—an order of epicellular parasitic [[Conoidasida]].<ref name=Perkins2000>{{cite book |vauthors=Perkins FO, Barta JR, Clopton RE, Peirce MA, Upton SJ |chapter=Phylum Apicomplexa |veditors=Lee JJ, Leedale GF, Bradbury P |title=An Illustrated guide to the Protozoa: organisms traditionally referred to as protozoa, or newly discovered groups |publisher=Society of Protozoologists |edition=2nd |year=2000 |oclc=704052757 |isbn=1891276220  |pages=190–369 |volume=1}}</ref><ref name=Simdyanov2017>Simdyanov TG, Guillou L, Diakin AY, Mikhailov KV, Schrével J, Aleoshin VV. (2017) A new view on the morphology and phylogeny of eugregarines suggested by the evidence from the gregarine ''Ancora sagittata'' (Leuckart, 1860) Labbé, 1899 (Apicomplexa: Eugregarinida) ''PeerJ'' 5:e3354 {{doi|10.7717/peerj.3354}}</ref>
The mucron is derived from the [[apical complex]], which is found in all members of the [[phylum]] [[Apicomplexa]].<ref name=Perkins2000/><ref name=Adl2012>Adl SM, Simpson AG, Lane CE, Lukeš J, Bass D, Bowser SS, Brown M, Burki F, Dunthorn M, Hampl V, Heiss A, Hoppenrath M, Lara E, leGall L, Lynn DH, McManus H, Mitchell EAD, Mozley-Stanridge SE, Parfrey LW, Pawlowski J, Rueckert S, Shadwick L, Schoch C, Smirnov A, Spiegel FW. (2012) The revised classification of eukaryotes. ''Journal of Eukaryotic Microbiology'' 59:429-514. {{doi|10.1111/j.1550-7408.2012.00644.x}}</ref>
The mucron is located at the anterior (apical) end of the cell and comprises the [[conoid (organelle)|conoid]], [[rhoptries]], apical [[polar ring]](s), and a large food [[vacuole]] (also called mucronal vacuole) having an outlet opening—a [[cytostome]]. It  is used to attach and feed from the host's cell.<ref name=Schrével1971>Schrével J. (1971) Observations biologiques et ultrastructurales sur les Selenidiidae et leurs conséquences sur la systématique des Grégarinomorphes. ''Journal of Protozoology'' 18:448–479. {{doi|10.1111/j.1550-7408.1971.tb03355.x}}</ref><ref name=Schrével2016>Schrével J, Valigurová A, Prensier G, Chambouvet A, Florent I, Guillou L. (2016) Ultrastructure of ''Selenidium pendula'', the type species of archigregarines, and phylogenetic relations to other marine Apicomplexa. ''Protist'' 167:339-368. {{doi|10.1016/j.protis.2016.06.001}}</ref><ref name=Simdyanov2007>Simdyanov TG, Kuvardina ON. (2007) Fine structure and putative feeding mechanism of the archigregarine ''Selenidium orientale'' (Apicomplexa: Gregarinomorpha). ''European Journal of Protistology'' 43:17-25. {{doi|10.1016/j.ejop.2006.09.003}}</ref>
The [[epimerite]]s of some aseptate [[Eugregarinorida|eugregarine]]s superficially (at the light microscopic level) resemble mucron and are usually called in the same way.<ref name=Perkins2000/><ref name=Adl2012/><ref name=Simdyanov2017/> This widespread misunderstanding originated from the conventional definition first proposed by Levine in 1971: "[the mucron is] an attachment organelle of aseptate gregarines. It is similar to an epimerite, but is not set off from the rest of the gregarine body by what appears under the light microscope to be a septum."<ref name=Levine1971>Levine ND. (1971) Uniform terminology for the protozoan subphylum Apicomplexa. ''Journal of Protozoology'' 18:352-355. {{doi|10.1111/j.1550-7408.1971.tb03330.x}}</ref>  Thus, it may be equally applied to archigregarines and aseptate eugregarines as both they are aseptate. Note that the genuine epimerites are usually not separated by septa from the rest of the cell,<ref name=Grasse1953>{{cite book |first=P.P. |last=Grassé |first2=M.C. |last2=Caullery |title=Traité de zoologie: anatomie, systématique, biologie. Tome I, Fasc. II, Protozaires, rhizopodes, Actinopodes, Sporozoaires, Cnidosporidies |publisher=Masson et Cie |location=Paris |year=1953 |oclc=642231286 }}</ref><ref name=Desportes2013>Desportes I, Schrével J. (2013) Treatise on Zoology - Anatomy, Taxonomy, Biology. ''The Gregarines''.  Leiden: Brill. {{doi|10.1163/9789004256057}} {{isbn|978-90-04-25605-7}}</ref> so this definition is misleading.<ref name=Simdyanov2017/>
==References==
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[[Category:Organelles]]
[[Category:Conoidasida]]