DOI: 10.1126/science.1141758 , 111 (2007); 317Science et al.Eske Willerslev,Forested Southern GreenlandAncient Biomolecules from Deep Ice Cores Reveal a www.sciencemag.org (this information is current as of October 20, 2009 ):The following resources related to this article are available online at http://www.sciencemag.org/cgi/content/full/317/5834/111version of this article at: including high-resolution figures, can be found in the onlineUpdated information and services, http://www.sciencemag.org/cgi/content/full/317/5834/111/DC1 can be found at: Supporting Online Materialfound at: can berelated to this articleA list of selected additional articles on the Science Web sites http://www.sciencemag.org/cgi/content/full/317/5834/111#related-content http://www.sciencemag.org/cgi/content/full/317/5834/111#otherarticles, 7 of which can be accessed for free: cites 27 articlesThis article 21 article(s) on the ISI Web of Science. cited byThis article has been http://www.sciencemag.org/cgi/content/full/317/5834/111#otherarticles 6 articles hosted by HighWire Press; see: cited byThis article has been http://www.sciencemag.org/cgi/collection/paleoPaleontology : subject collectionsThis article appears in the following http://www.sciencemag.org/about/permissions.dtl in whole or in part can be found at: this articlepermission to reproduce of this article or about obtaining reprintsInformation about obtaining registered trademark of AAAS. is aScience2007 by the American Association for the Advancement of Science; all rights reserved. The title CopyrightAmerican Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005. (print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by theScience on October 20, 2009 www.sciencemag.orgDownloaded from23. L. Mehl, B. R. Hacker, G. Hirth, P. B. Kele men,J. Geophys. Res. 108, 10.1029/2002JB002233(2003).24. B. R. Jicha, D. W. Scholl, B. S. Singer, G. M. Yogodzinski,S. M. Kay, Geology 34, 661 (2006).25. C.-T. Lee, X. Cheng, U. Horodyskyj, Contrib. Min. Petrol.151, 222 (2006).26. P. B. Kelemen, K. Hanghøj, A. R. Greene, in The Crust,R. L. Rudnick, Ed. (Elsevier-Pergamon, Oxford, 2003),vol. 3, pp. 593–659.27. T. V. Gerya, D. A. Yuen, Earth Planet. Sci. Lett. 212, 47(2003).28. We thank M. Long, E. Kneller, and C. Conrad forconversations that motivated this work. Funding wasprovided by NSF grants EAR-9910899, EAR-0125919, andEAR-0509882.Supporting Online Materialwww.sciencemag.org/cgi/content/full/317/5834/108/DC1SOM TextFigs. S1 and S2References13 February 2007; accepted 9 May 200710.1126/science.1141269Ancient Biomolecules fromDeep Ice Cores Reveal a ForestedSouthern GreenlandEske Willerslev,1* Enrico Cappellini,2Wouter Boomsma,3Rasmus Nielsen,4Martin B. Hebsgaard,1Tina B. Brand,1Michael Hofreiter,5Michael Bunce,6,7Hendrik N. Poinar,7Dorthe Dahl-Jensen,8Sigfus Johnsen,8Jørgen Peder Steffensen,8Ole Bennike,9Jean-Luc Schwenninger,10Roger Nathan,10Simon Armitage,11Cees-Jan de Hoog,12Vasily Alfimov,13Marcus Christl,13Juerg Beer,14Raimund Muscheler,15Joel Barker,16Martin Sharp,16Kirsty E. H. Penkman,2James Haile,17Pierre Taberlet,18M. Thomas P. Gilbert,1Antonella Casoli,19Elisa Campani,19Matthew J. Collins2It is difficult to obtain fossil data from the 10% of Earth’s terrestrial surface that is covered by thickglaciers and ice sheets, and hence, knowledge of the paleoenvironments of these regions hasremained limited. We show that DNA and amino acids from buried organisms can be recoveredfrom the basal sections of deep ice cores, enabling reconstructions of past flora and fauna. Weshow that high-altitude southern Greenland, currently lying below more than 2 kilometers of ice,was inhabited by a diverse array of conifer trees and insects within the past million years. Theresults provide direct evidence in support of a forested southern Greenland and suggest that manydeep ice cores may contain genetic records of paleoenvironments in their basal sections.The environmental histories of high-latituderegions such as Greenland and Antarcticaare poorly understood because much ofthe fossil evidence is hidden below kilometer-thick ice sheets (1–3). We test the idea that thebasal sections of deep ice cores can act asarchives for ancient biomolecules.The samples studied come from the basalimpurity-rich (silty) ice sections of the 2-km-long Dye 3 core from south-central Greenland(4), the 3-km-long Greenland Ice Core Project(GRIP) core from the summit of the Greenlandice sheet (5), and the Late Holocene John EvansGlacier on Ellesmere Island, Nunavut, northernCanada (Fig. 1). The last-mentioned sample wasincluded as a control to test for potential exoticDNA because the glacier has recently overriddena land surface with a known vegetation cover(6). As an additional test for long-distanceatmospheric dispersal of DNA, we includedfive control samples of debris-free Holoceneand Pleistocene ice taken just above the basalsilty samples from the Dye 3 and GRIP icecores (Fig. 1B). Finally, our analyses includedsediment samples from the Kap KøbenhavnFormation from the northernmost part ofGreenland, dated to 2.4 million years beforethe present (Ma yr B.P.) (1, 2).The silty ice yielded only a few pollen grainsand no macrofossils (7). However, the Dye 3and John Evans Glacier silty ice samples showedlow levels of amino acid racemization (Fig. 1A,inset), indicating good organic matter preserva-tion (8). Therefore, after previous success withpermafrost and cave sediments (9–11), we at-tempted to amplify ancient DNA from the ice.This was done following strict criteria to secureauthenticity (12 –14), including covering the sur-face of the frozen cores with plasmid DNA tocontrol for potential contamination that mayhave entered the interior of the samples throughcracks or during the sampling procedure (7).Polymerase chain reaction (PCR) products ofthe plasmid DNA were obtained only from ex-tracts of the outer ice scrapings but not from theinterior, confirming that sample contaminationhad not penetrated the cores.Using PCR, we could reproducibly amplifyshort amplicons [59 to 120 base pairs (bp)] ofthe chloroplast DNA (cpDNA) rbcL gene andtrnL intron from ~50 g of the interior ice meltsfrom the Dye 3 and the John Evans Glacier siltysamples. From Dye 3, we also obtained 97-bpamplicons of invertebrate cytochrome oxidasesubunit I (COI) mitochondrial DNA (mtDNA).Attempts to reproducibly amplify DNA fromthe GRIP
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