HR: 16:45h
AN: PP14B-04 INVITED     [Abstracts]
TI: Fossil DNA as a Recorder of Ancient Microbial Communities and Palaeoenvironments
AU: * Coolen, M J
EM: mcoolen@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, MA 02543 United States
AU: * Coolen, M J
EM: mcoolen@whoi.edu
AF: Royal Netherlands Institute for Sea Research, Department of Marine Biogeochemistry and Toxicology, P.O. Box 59, Den Burg, 1790 AB Netherlands
AU: Boere, A
EM: aboere@nioz.nl
AF: Royal Netherlands Institute for Sea Research, Department of Marine Biogeochemistry and Toxicology, P.O. Box 59, Den Burg, 1790 AB Netherlands
AU: Abbas, B
EM: abbas@nioz.nl
AF: Royal Netherlands Institute for Sea Research, Department of Marine Biogeochemistry and Toxicology, P.O. Box 59, Den Burg, 1790 AB Netherlands
AU: Muyzer, G
EM: g.muyzer@tnw.tudelft.nl
AF: Delft University of Technology, Department of Biotechnology, Julianalaan 67, Delft, 2628 BC Netherlands
AU: Overmann, J
EM: J.Overmann@lrz.uni-muenchen.de
AF: Skidaway Institute of Oceanography, 10 Ocean Science Circle, Savannah, GA 31411 United States
AU: Wakeham, S G
EM: stuart@skio.peachnet.edu
AF: Ludwig-Maxilians-University, Maria-Ward Strasse 1a, Munich, D-80638 Germany
AU: Volkman, J K
EM: John.Volkman@csiro.au
AF: Antarctic CRC and CSIRO Marine Research, GPO Box 1538, Hobart, Tasmania, 7001 Australia
AU: Sinninghe Damste, J S
EM: damste@nioz.nl
AF: Royal Netherlands Institute for Sea Research, Department of Marine Biogeochemistry and Toxicology, P.O. Box 59, Den Burg, 1790 AB Netherlands
AB: Fossilized organic components provide an archive of ancient aquatic microbial communities and, hence, can be used to reconstruct climate-induced environmental changes and their impacts on biodiversity. However, the interpretation of these data is complicated by the limited source specificity of some traditional biomarkers, such as lipids and pigments. The ultimate biomarkers are genes encoding for ribosomal RNA (rDNA), which sequences provide information at the species level by phylogenetic comparison but until recently was only applied to identify extant species within environmental samples. With the exception of excellent preservation conditions prevailing in permafrost sediments (3), it was generally believed that DNA becomes rapidly degraded within fossil records. However, we have recently shown that especially in the presence of hydrogen sulfide, DNA can survive in the Holocene fossil record (1, 2). In this presentation we will show how, and to what extent, fossil DNA extracted from Holocene sediments of stratified lakes (the Canadian Mahoney Lake and the Antarctic Ace Lake) and the deep-sea (Black Sea) can be used as a novel proxy to reconstruct the ancient palaeodepositional environments and evolution of past microbial communities. In addition, we will discuss the fate of fossil DNA; quantitative stratigraphic analysis of lipid biomarkers and rDNA from the same biological precursors revealed information on the survival of fossil DNA in comparison to lipid biomarkers. It was shown that most of the DNA was degraded before dead cells reach the bottom but the remaining part was found to be well protected and even less prone to diagenetic alteration compared to certain lipid biomarkers. Base-pair compositions did not change during the Holocene, however, the fossil DNA became fragmented after several thousands of years of deposition but without significantly biasing the qualitative and quantitative molecular biological analysis of at least 10-ka-old fossil DNA. Furthermore, we will discuss examples which show the relevance of the identification of the ancient aquatic microbial community members at the unprecedented species-level using fossil rDNA as a novel palaeoproxy.
(1) Coolen, MJL., et al., Combined DNA and lipid analyses of sediments reveal changes in Holocene haptophyte and diatom populations in an Antarctic lake , Earth. Planet. Sc. Lett., 223, 225-239, 2004.
(2) Coolen, MJL and J. Overmann, Analysis of subfossil molecular remains of purple sulfur bacteria in a lake sediment, Appl. Environ. Microbiol., 64(11), 4513-4521, 1998.
(3) Willerslev, E., et al. Diverse plant and animal genetic records from Holocene and Pleistocene sediments, Science, 300(5620), 791-795, 2003.
DE: 0404 Anoxic and hypoxic environments (4802, 4834)
DE: 0424 Biosignatures and proxies
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 1051 Sedimentary geochemistry
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005