{"id":1967,"date":"2024-04-15T07:14:28","date_gmt":"2024-04-15T07:14:28","guid":{"rendered":"https:\/\/deliry.net\/?p=514"},"modified":"2026-04-13T15:13:27","modified_gmt":"2026-04-13T15:13:27","slug":"cyanobacteries-et-la-grande-oxygenation-de-lenvironnement","status":"publish","type":"post","link":"https:\/\/deliry.com\/?p=1967","title":{"rendered":"Cyanobact\u00e9ries et la Grande Oxyg\u00e9nation de l&rsquo;Environnement"},"content":{"rendered":"\n<p>Il est convenu que les Cyanobact\u00e9ries ont jou\u00e9 un r\u00f4le important dans la Grande Oxyg\u00e9nation de l\u2019Environnement. La pr\u00e9sence d\u2019oxyg\u00e8ne si elle est attest\u00e9e plus anciennement, l\u2019\u00e9tude phylog\u00e9n\u00e9tique des lign\u00e9es enzymatiques indiquent que de l\u2019oxyg\u00e8ne est bien disponible d\u00e8s 3,1 Ga et que la photosynth\u00e8se oxyg\u00e9nique existe d\u00e8s 3,0 Ga. Les plus anciennes Cyanobact\u00e9ries ne devaient pas poss\u00e9der de thylako\u00efdes. Lorsque ces esp\u00e8ces en ont, ils pr\u00e9sentent une grande diversit\u00e9 de position dans les cellules. La divergence de Cyanobact\u00e9ries est estim\u00e9e par la m\u00e9thode phylog\u00e9n\u00e9tique vers 1,4 Ga, ce qui date l\u2019apparition des thylako\u00efdes. Si on avait fait des observations pal\u00e9ontologiques directes de Cyanobact\u00e9ries d\u00e8s 2,0 Ga, les observations de thylako\u00efdes dataient tout au plus de l\u2019\u00c9diacarien sup\u00e9rieur (550 Ma) (algues). Demoulin &amp; al. (2023) rendent compte de la pr\u00e9sence de thylako\u00efdes chez une probable Cyanobact\u00e9rie dont la lign\u00e9e reste difficile \u00e0 pr\u00e9ciser,&nbsp;<em>Navifusa majensis&nbsp;<\/em>\u0166 dat\u00e9e de plus de 1,7 Ga (Australie). Ceci repousse par l\u2019observation pal\u00e9ontologique directe de fossiles la date de divergence des lign\u00e9es \u00e0 thylako\u00efde \u00e0 nettement plus de 1,4 Ga comme l\u2019avait calcul\u00e9e la m\u00e9thode phylog\u00e9n\u00e9tique.<\/p>\n\n\n\n<p><strong>Demoulin C.F. &amp; al. 2023<\/strong>&nbsp;\u2013 Oldest thylakoids in fossil cells directly evidence oxygenic photosynthesis. \u2013&nbsp;<em>Nature,&nbsp;<\/em>3 janvier 2024. \u2013&nbsp;<a href=\"https:\/\/www.nature.com\/articles\/s41586-023-06896-7.epdf?sharing_token=otYCgcfosF2eifKERHa0h9RgN0jAjWel9jnR3ZoTv0OlAxnviW_NU_UK25d87SUcPDgDdGLHdXN8IBlwcyXzE5pX77wQauWuACqoB5bk8l9QliO2pUStrdw4OMB8ABEA-WvtQRDBORD_4yeWRGxSCez64xqG87NZp56g3NTLKS64sDFWkqRNP2uooZ01mB9AgXmspw3XMaRGtvxZuFAucontk87DwWR9uHLCQQyA5I8=&amp;tracking_referrer=www.lemonde.fr\" target=\"_blank\" rel=\"noreferrer noopener\">ONLINE<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Il est convenu que les Cyanobact\u00e9ries ont jou\u00e9 un r\u00f4le important dans la Grande Oxyg\u00e9nation de l\u2019Environnement. La pr\u00e9sence d\u2019oxyg\u00e8ne si elle est attest\u00e9e plus &hellip; <\/p>\n","protected":false},"author":1,"featured_media":2561,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[414,413,411,1,311],"tags":[],"class_list":["post-1967","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-atmosphere","category-bacteries","category-changements-climatiques","category-maintenance","category-zz-synchroniser"],"_links":{"self":[{"href":"https:\/\/deliry.com\/index.php?rest_route=\/wp\/v2\/posts\/1967","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/deliry.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/deliry.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/deliry.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/deliry.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1967"}],"version-history":[{"count":4,"href":"https:\/\/deliry.com\/index.php?rest_route=\/wp\/v2\/posts\/1967\/revisions"}],"predecessor-version":[{"id":7615,"href":"https:\/\/deliry.com\/index.php?rest_route=\/wp\/v2\/posts\/1967\/revisions\/7615"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/deliry.com\/index.php?rest_route=\/wp\/v2\/media\/2561"}],"wp:attachment":[{"href":"https:\/\/deliry.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1967"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/deliry.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1967"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/deliry.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1967"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}