{"id":5745,"date":"2022-01-19T17:39:45","date_gmt":"2022-01-19T21:39:45","guid":{"rendered":"https:\/\/www.jcvignoli.com\/blog\/?p=5745"},"modified":"2022-01-19T17:39:45","modified_gmt":"2022-01-19T21:39:45","slug":"antarctique-la-vie-existe-la-ou-lon-ne-devrait-pas-la-trouver","status":"publish","type":"post","link":"https:\/\/www.jcvignoli.com\/blog\/2022\/antarctique-la-vie-existe-la-ou-lon-ne-devrait-pas-la-trouver","title":{"rendered":"Antarctique: la vie existe l\u00e0 o\u00f9 l’on ne devrait pas la trouver"},"content":{"rendered":"

En Antarctique, dans l\u2019un des lieux les plus sombres et les plus froids de la plan\u00e8te, viennent d\u2019\u00eatre d\u00e9couvert des dizaines d\u2019organismes se reproduisant en toute qui\u00e9tude depuis des milliers d\u2019ann\u00e9es. \u00ab\u00a0L\u2019approche scientifique de la vie est peut-\u00eatre \u00e0 revoir\u00a0; notre d\u00e9couverte d\u2019une faune abondante dans l\u2019un des milieux les plus inhospitalier de la Terre, bouleverse notre compr\u00e9hension de la vie. Et si, apr\u00e8s tout, ce que nous croyons \u00eatre un environnement hostile, ne l\u2019\u00e9tait pas\u00a0? \u00a0\u00bb, commence le Dr David Barnes, co-auteur principal de l\u2019\u00e9tude parue dans Current Biology<\/i>[1]<\/a><\/sup>.<\/p>\n

C\u2019est en 2018 qu\u2019une \u00e9quipe de biologistes allemands s\u2019aventure loin, tr\u00e8s loin sur les plate-formes glaciaires antarctiques. La terre ferme n\u2019est qu\u2019un lointain souvenir, et l\u2019oc\u00e9an \u00e0 plusieurs kilom\u00e8tres. L\u2019objectif de l\u2019exp\u00e9dition est d\u2019extraire un \u00e9chantillon d\u2019eau liquide, apr\u00e8s avoir creus\u00e9 \u00e0 travers plusieurs centaines de m\u00e8tre de la surface gel\u00e9e. Il s\u2019agit de l\u2019un des lieux les plus froids, sombre, et isol\u00e9 de la plan\u00e8te\u00a0: 1,6 millions de kilom\u00e8tres carr\u00e9s compl\u00e8tement blancs. \u00ab\u00a0A vrai dire, l\u2019\u00e9quipe ne pensait pas trouver grand chose. Elle \u00e9tait consciente que rien ne devrait se trouver l\u00e0-dessous. C\u2019est pourquoi lors de l\u2019analyse de l\u2019\u00e9chantillon, trois ans plus tard, la surprise fut totale\u00a0: 77 organismes vivent et ont v\u00e9cu durant des milliers d\u2019ann\u00e9es. Les tests au carbone 14 font remonter certains des cadavres \u00e0 5300 ans\u00a0!\u00a0\u00bb, fait avec excitation le scientifique, qui a d\u00e9couvert des escargots, des mousses, des verts marins, des bivalves et des coraux.<\/p>\n

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credit: AWI<\/figcaption><\/figure>\n

Les biologistes allemands, lors de leur retour, recherchent un laboratoire capable d\u2019analyser leurs \u00e9chantillons. C\u2019est ainsi qu\u2019ils tombent sur Barnes et son \u00e9quipe, et que leur collaboration va battre en br\u00e8che ce qu\u2019on croit conna\u00eetre de la vie en Antarctique\u00a0: que le d\u00e9veloppement cellulaire serait n\u00e9cessairement lent, ou que la survie d\u00e9pendant immanquablement d\u2019une source r\u00e9guli\u00e8re de nourriture. \u00ab\u00a0Or, commence le biologiste anglais, aucun plancton ne se d\u00e9veloppe \u00e0 cet endroit, les donn\u00e9es sont claires. Et le d\u00e9veloppement organique est tout \u00e0 fait r\u00e9gulier.\u00a0\u00bb Si le myst\u00e8re de l\u2019approvisionnement de nourriture se r\u00e9sout relativement vite – les courants sous-marins apportent du plancton aux animaux relativement immobiles aux m\u00eames endroits -, la question de savoir pourquoi le froid intense ne ralentit pas le m\u00e9tabolisme reste elle enti\u00e8re.<\/p>\n

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credit: AWI<\/figcaption><\/figure>\n

\u00ab\u00a0La croissance de ces animaux est normale, bien qu\u2019ils aient une \u00e9volution g\u00e9n\u00e9tique tr\u00e8s lente. Ils peuvent vivre plusieurs dizaines d\u2019ann\u00e9es, mais ce n\u2019est en moyenne qu\u2019\u00e0 partir de la moiti\u00e9 de leur existence qu\u2019ils peuvent procr\u00e9er. Cette reproduction, si lente, explique pourquoi ces animaux ont si peu \u00e9volu\u00e9 au fil du temps\u00a0\u00bb, indique le chercheur.<\/p>\n

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credit BAS<\/figcaption><\/figure>\n

Malgr\u00e9 l\u2019incroyable adaptation de ces \u00e9cosyst\u00e8mes extr\u00e9mophiles, le Dr Barnes juge leur survie pr\u00e9caire\u00a0: \u00ab\u00a0Ils doivent leur existence au fait qu\u2019ils sont \u00e9loign\u00e9s de tout. Des temp\u00eates, des bouleversements de notre plan\u00e8te, et surtout des activit\u00e9s humaines. Avec le r\u00e9chauffement climatique, ils risquent d\u2019\u00eatre condamn\u00e9s \u00e0 dispara\u00eetre rapidement. \u00bb<\/p>\n

Les p\u00f4les, au m\u00eame titre que les grande for\u00eats, retiennent une importante quantit\u00e9 de carbone. Bien que leur efficience de stockage soit moindre, leur superficie qui s’\u00e9tend sur des millions de kilom\u00e8tres carr\u00e9s, rel\u00e2chant ou capturant sur des longues p\u00e9riodes le carbone, les rends vitaux pour la survie de la plan\u00e8te. L’extinction prochaine de ces animaux antarctiques pourrait n’\u00eatre qu’un pr\u00e9lude \u00e0 une catastrophe \u00e0 plus grande \u00e9chelle.<\/p>\n

\n

R\u00e9f\u00e9rences<\/p>\n<\/div>\n<\/div>

  1. Current Biology<\/i><\/a>[<\/span>\u21a9<\/a>]<\/span><\/span><\/li><\/ol>
    \r\n
    \r\n \r\n <\/i>\r\n <\/a>\r\n 0 <\/span>\r\n<\/div>
    \r\n \r\n <\/i>\r\n <\/a>\r\n 0<\/span>\r\n<\/div><\/div>","protected":false},"excerpt":{"rendered":"

    En Antarctique, dans l\u2019un des lieux les plus sombres et les plus froids de la plan\u00e8te, viennent d\u2019\u00eatre d\u00e9couvert des dizaines d\u2019organismes se reproduisant en toute qui\u00e9tude depuis des milliers d\u2019ann\u00e9es. \u00ab\u00a0L\u2019approche scientifique de la vie est peut-\u00eatre \u00e0 revoir\u00a0; notre d\u00e9couverte d\u2019une faune abondante dans l\u2019un des milieux les plus inhospitalier de la Terre, […]<\/p>\n","protected":false},"author":1,"featured_media":5746,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ocean_post_layout":"","ocean_both_sidebars_style":"","ocean_both_sidebars_content_width":0,"ocean_both_sidebars_sidebars_width":0,"ocean_sidebar":"0","ocean_second_sidebar":"0","ocean_disable_margins":"enable","ocean_add_body_class":"","ocean_shortcode_before_top_bar":"","ocean_shortcode_after_top_bar":"","ocean_shortcode_before_header":"","ocean_shortcode_after_header":"","ocean_has_shortcode":"","ocean_shortcode_after_title":"","ocean_shortcode_before_footer_widgets":"","ocean_shortcode_after_footer_widgets":"","ocean_shortcode_before_footer_bottom":"","ocean_shortcode_after_footer_bottom":"","ocean_display_top_bar":"default","ocean_display_header":"default","ocean_header_style":"","ocean_center_header_left_menu":"0","ocean_custom_header_template":"0","ocean_custom_logo":0,"ocean_custom_retina_logo":0,"ocean_custom_logo_max_width":0,"ocean_custom_logo_tablet_max_width":0,"ocean_custom_logo_mobile_max_width":0,"ocean_custom_logo_max_height":0,"ocean_custom_logo_tablet_max_height":0,"ocean_custom_logo_mobile_max_height":0,"ocean_header_custom_menu":"0","ocean_menu_typo_font_family":"0","ocean_menu_typo_font_subset":"","ocean_menu_typo_font_size":0,"ocean_menu_typo_font_size_tablet":0,"ocean_menu_typo_font_size_mobile":0,"ocean_menu_typo_font_size_unit":"px","ocean_menu_typo_font_weight":"","ocean_menu_typo_font_weight_tablet":"","ocean_menu_typo_font_weight_mobile":"","ocean_menu_typo_transform":"","ocean_menu_typo_transform_tablet":"","ocean_menu_typo_transform_mobile":"","ocean_menu_typo_line_height":0,"ocean_menu_typo_line_height_tablet":0,"ocean_menu_typo_line_height_mobile":0,"ocean_menu_typo_line_height_unit":"","ocean_menu_typo_spacing":0,"ocean_menu_typo_spacing_tablet":0,"ocean_menu_typo_spacing_mobile":0,"ocean_menu_typo_spacing_unit":"","ocean_menu_link_color":"","ocean_menu_link_color_hover":"","ocean_menu_link_color_active":"","ocean_menu_link_background":"","ocean_menu_link_hover_background":"","ocean_menu_link_active_background":"","ocean_menu_social_links_bg":"","ocean_menu_social_hover_links_bg":"","ocean_menu_social_links_color":"","ocean_menu_social_hover_links_color":"","ocean_disable_title":"default","ocean_disable_heading":"default","ocean_post_title":"","ocean_post_subheading":"","ocean_post_title_style":"","ocean_post_title_background_color":"","ocean_post_title_background":0,"ocean_post_title_bg_image_position":"","ocean_post_title_bg_image_attachment":"","ocean_post_title_bg_image_repeat":"","ocean_post_title_bg_image_size":"","ocean_post_title_height":0,"ocean_post_title_bg_overlay":0.5,"ocean_post_title_bg_overlay_color":"","ocean_disable_breadcrumbs":"default","ocean_breadcrumbs_color":"","ocean_breadcrumbs_separator_color":"","ocean_breadcrumbs_links_color":"","ocean_breadcrumbs_links_hover_color":"","ocean_display_footer_widgets":"default","ocean_display_footer_bottom":"default","ocean_custom_footer_template":"0","ocean_post_oembed":"","ocean_post_self_hosted_media":"","ocean_post_video_embed":"","ocean_link_format":"","ocean_link_format_target":"self","ocean_quote_format":"","ocean_quote_format_link":"post","ocean_gallery_link_images":"off","ocean_gallery_id":[],"footnotes":""},"categories":[15,3,1860],"tags":[14928,184,1379],"class_list":["post-5745","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-articles","category-ecologie","category-interview","tag-antarctique","tag-science","tag-vie","entry","has-media"],"aioseo_notices":[],"language":"fr","_links":{"self":[{"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/posts\/5745","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/comments?post=5745"}],"version-history":[{"count":3,"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/posts\/5745\/revisions"}],"predecessor-version":[{"id":5755,"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/posts\/5745\/revisions\/5755"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/media\/5746"}],"wp:attachment":[{"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/media?parent=5745"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/categories?post=5745"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jcvignoli.com\/blog\/wp-json\/wp\/v2\/tags?post=5745"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}