{"id":2425,"date":"2011-06-13T18:04:18","date_gmt":"2011-06-13T16:04:18","guid":{"rendered":"http:\/\/codexvirtualis.fr\/codex\/?page_id=2425"},"modified":"2015-05-27T21:48:11","modified_gmt":"2015-05-27T19:48:11","slug":"la-moule-et-son-rocher","status":"publish","type":"page","link":"https:\/\/codexvirtualis.fr\/codex\/cabinet-de-curiosites-virtuel\/images-insolites-instructives\/la-moule-et-son-rocher","title":{"rendered":"La Moule et son rocher"},"content":{"rendered":"<p> &nbsp; <\/p>\n<figure style=\"width: 300px\" class=\"wp-caption alignnone\"><a rel=\"lightbox\" href=\"\/documents\/images\/Mytilus_edulis\/Mytilus_edulis07_11byssus-WEB.jpg\" target=\"_blank\"><img decoding=\"async\" alt=\"Byssus de Moule\" src=\"\/documents\/images\/Mytilus_edulis\/Mytilus_edulis07_11byssus-WEB.jpg\" title=\"Byssus de Moule\" width=\"300\" \/><\/a><figcaption class=\"wp-caption-text\">Byssus de la Moule (Mytilus edulis - Crozon, 2011)<\/figcaption><\/figure>\n<p> &nbsp; <\/p>\n<p>La Moule (<em>Mytilus edulis<\/em>) est un animal fr\u00e9quent sur les c\u00f4tes rocheuses. Elle vit fix\u00e9e sur les rochers gr\u00e2ce \u00e0 un ensemble de filaments d\u00e9sign\u00e9 par le terme byssus. Celui-ci prend naissance en-dessous du pied et forme un faisceau de fibres divergentes, qui adh\u00e8rent au support par l&rsquo;interm\u00e9diaire d&rsquo;une plaque arrondie.<\/p>\n<p>Les propri\u00e9t\u00e9s du byssus sont \u00e9tonnantes : il est cinq fois plus r\u00e9sistant et seize fois plus extensible qu&rsquo;un tendon humain !<\/p>\n<p>Quelle est leur origine ? Comment le byssus permet il la fixation sur le substrat ?<\/p>\n<p> &nbsp; <\/p>\n<p>Les filaments qui constituent le byssus sont form\u00e9s :<\/p>\n<p><span style=\"color: #999999;\">\u2022 <\/span>d&rsquo;une partie proximale, proche du corps et ancr\u00e9e dans la base du pied, \u00e9lastique ;<\/p>\n<p><span style=\"color: #999999;\">\u2022 <\/span>d&rsquo;une partie distale, proche de la plaque adh\u00e9sive, rigide et peu d\u00e9formable.<\/p>\n<p>En cons\u00e9quence, ils sont capables d&rsquo;une part d&rsquo;absorber la force des vagues, jouant le r\u00f4le d&rsquo;amortisseur, et d&rsquo;autre part assurent un ancrage tr\u00e8s solide au substrat.<\/p>\n<p> &nbsp; <\/p>\n<p>Les propri\u00e9t\u00e9s des deux parties des filaments sont li\u00e9es \u00e0 leur organisation et leur composition. Deux types de collag\u00e8ne sont pr\u00e9sents dans le byssus. Le collag\u00e8ne proximal a des qualit\u00e9s d&rsquo;\u00e9lasticit\u00e9 alors que le collag\u00e8ne distal a des qualit\u00e9s de r\u00e9sistance. Ces collag\u00e8nes co-existent sur la longueur des filaments du byssus, en gradients inverses.<\/p>\n<p>La portion proximale doit son \u00e9lasticit\u00e9 \u00e0 l&rsquo;existence de domaines semblables \u00e0 l&rsquo;\u00e9lastine, associ\u00e9s au collag\u00e8ne.<br \/>\nLa rigidit\u00e9 de la partie distale est quant \u00e0 elle li\u00e9e \u00e0 la pr\u00e9sence de ponts transversaux tr\u00e8s r\u00e9sistants, reliant entre elles les fibres de collag\u00e8ne et se reconstituant tr\u00e8s rapidement apr\u00e8s destruction.<\/p>\n<p> &nbsp; <\/p>\n<figure style=\"width: 300px\" class=\"wp-caption alignnone\"><a rel=\"lightbox\" href=\"\/documents\/images\/Mytilus_edulis\/Mytilus_edulis_2005byssus-WEB.jpg\" target=\"_blank\"><img decoding=\"async\" alt=\"Filaments du byssus\" src=\"\/documents\/images\/Mytilus_edulis\/Mytilus_edulis_2005byssus-WEB.jpg\" title=\"Filaments du byssus\" width=\"300\" \/><\/a><figcaption class=\"wp-caption-text\">Filaments du byssus de la Moule (Mytilus edulis - Crozon, 2005)<\/figcaption><\/figure>\n<p> &nbsp; <\/p>\n<p>L&rsquo;adh\u00e9rence au substrat implique des prot\u00e9ines, appel\u00e9es prot\u00e9ines du pied, organis\u00e9es en r\u00e9seau du fait de liaisons inter-mol\u00e9culaires. Ces derni\u00e8res favorisent non seulement la r\u00e9sistance m\u00e9canique, mais aussi l\u2019adh\u00e9rence au substrat.<\/p>\n<p><em>Les prot\u00e9ines du pied (Mefp-1 \u00e0 4, pour Mytilus edulis foot protein) subissent un tannage quinonique, c&rsquo;est \u00e0 dire une oxydation des cha\u00eenes lat\u00e9rales de certains acides amin\u00e9s comme la L-DOPA\u00a0(3,4-dihydroxyph\u00e9nyl-L-alanine) conduisant \u00e0 leur transformation en quinones, suivie d&rsquo;une polym\u00e9risation. L&rsquo;une des enzymes catalysant ces r\u00e9actions est une polyph\u00e9noloxydase, d\u00e9pendante du cuivre. Des ponts disulfure sont \u00e9galement pr\u00e9sents, entre les r\u00e9sidus cyst\u00e9ine de ces prot\u00e9ines.<\/em><\/p>\n<p> &nbsp; <\/p>\n<p>La r\u00e9sistance des filaments de byssus \u00e0 l&rsquo;abrasion due aux vagues est li\u00e9e \u00e0 la pr\u00e9sence d&rsquo;une cuticule externe de nature prot\u00e9ique. Elle est environ cinq fois plus dure que les fibres du c\u0153ur des filaments.<\/p>\n<p>La cuticule est form\u00e9e, chez certaines esp\u00e8ces, d&rsquo;une matrice prot\u00e9ique contenant des granules au sein desquels les prot\u00e9ines forment des assemblages complexes stabilis\u00e9s par l&rsquo;association avec des ions ferriques (Fe3+).<br \/>\nLa cuticule combine une grande rigidit\u00e9 et une importante extensibilit\u00e9. La premi\u00e8re serait li\u00e9e \u00e0 la densit\u00e9 des liaisons entre prot\u00e9ines au sein des granules alors que la seconde r\u00e9sulterait de la relative pauvret\u00e9 de la matrice en ce type de liaisons.<\/p>\n<p> &nbsp; <\/p>\n<p>R\u00e9f\u00e9rences :<\/p>\n<p><span style=\"color: #999999;\">\u2022 <\/span>Coyne K.J., Qin X.-X., Waite J.H., 1997 &#8211; Extensible collagen in mussel byssus : a natural block copolymer. Science, vol. 277 : 1830-1832.<br \/>\n<a href=\"http:\/\/dx.doi.org\/10.1126\/science.277.5333.1830 \" target=\"_blank\">DOI: 0.1126\/science.277.5333.1830<\/a><\/p>\n<p><span style=\"color: #999999;\">\u2022 <\/span>M.J. Harrington, A. Masic,N. Holten-Andersen, J.H. Waite, P. Fratzl, 2010 &#8211; Iron-clad fibers: a metal-based biological strategy for hard flexible coatings. Science, vol. 328 : 216-220.<br \/>\n<a href=\"http:\/\/dx.doi.org\/10.1126\/science.1181044 \" target=\"_blank\">DOI: 10.1126\/science.1181044<\/a><\/p>\n<p><span style=\"color: #999999;\">\u2022 <\/span>Messersmith P.B., 2010 &#8211; Holding on by a hard-shell thread. Science, vol. 328 : 180-181.<br \/>\n<a href=\"http:\/\/dx.doi.org\/10.1126\/science.1187598 \" target=\"_blank\">DOI: 10.1126\/science.1187598<\/a><\/p>\n<p> &nbsp; <\/p>\n<p>Pour acc\u00e9der au site internet de la revue <a href=\"http:\/\/www.sciencemag.org\/\" target=\"_blank\">Science<\/a> (adresse : http:\/\/www.sciencemag.org)<\/p>\n<p> &nbsp; <\/p>\n<p>Pour en savoir plus sur le byssus, consulter la page <a href=\"\/codex\/de-lorganisation-interne\/organe-byssogene-moule\">L&rsquo;organe byssog\u00e8ne et l&rsquo;\u00e9laboration du byssus<\/a> de la rubrique De l&rsquo;organisation interne<\/p>\n<p> &nbsp; <\/p>\n","protected":false},"excerpt":{"rendered":"<p>&nbsp; &nbsp; La Moule (Mytilus edulis) est un animal fr\u00e9quent sur les c\u00f4tes rocheuses. Elle vit fix\u00e9e sur les rochers gr\u00e2ce \u00e0 un ensemble de filaments d\u00e9sign\u00e9 par le terme byssus. Celui-ci prend naissance en-dessous du pied et forme un faisceau de fibres divergentes, qui adh\u00e8rent au support par l&rsquo;interm\u00e9diaire d&rsquo;une plaque arrondie. Les propri\u00e9t\u00e9s [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"parent":1788,"menu_order":3,"comment_status":"closed","ping_status":"closed","template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"class_list":["post-2425","page","type-page","status-publish","hentry"],"aioseo_notices":[],"jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/pages\/2425","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/comments?post=2425"}],"version-history":[{"count":31,"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/pages\/2425\/revisions"}],"predecessor-version":[{"id":7496,"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/pages\/2425\/revisions\/7496"}],"up":[{"embeddable":true,"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/pages\/1788"}],"wp:attachment":[{"href":"https:\/\/codexvirtualis.fr\/codex\/wp-json\/wp\/v2\/media?parent=2425"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}