“Ancient Marine Sediment DNA Reveals Diatom Transition in Antarctica”, Linda Armbrecht, Michael E. Weber, Maureen E. Raymo, Victoria L. Peck, Trevor Williams, Jonathan Warnock, Yuji Kato, Iván Hernández-Almeida, Frida Hoem, Brendan Reilly, Sidney Hemming, Ian Bailey, Yasmina M. Martos, Marcus Gutjahr, Vincent Percuoco, Claire Allen, Stefanie Brachfeld, Fabricio G. Cardillo, Zhiheng Du, Gerson Fauth, Chris Fogwill, Marga Garcia, Anna Glüder, Michelle Guitard, Ji-Hwan Hwang, Mutsumi Iizuka, Bridget Kenlee, Suzanne O’Connell, Lara F. Pérez, Thomas A. Ronge, Osamu Seki, Lisa Tauxe, Shubham Tripathi, Xufeng Zheng2022-10-02 (genome sequencing)⁠:

Antarctica is one of the most vulnerable regions to climate change on Earth and studying the past and present responses of this polar marine ecosystem to environmental change is a matter of urgency. Sedimentary ancient DNA (sedaDNA) analysis can provide such insights into past ecosystem-wide changes.

Here we present authenticated (through extensive contamination control and sedaDNA damage analysis) metagenomic marine eukaryote sedaDNA from the Scotia Sea region acquired during IODP Expedition 382. We also provide a marine eukaryote sedaDNA record of ~1 Mio. years and diatom and chlorophyte sedaDNA dating back to ~540 ka (using taxonomic marker genes SSU, LSU, psbO).

We find evidence of warm phases being associated with high relative diatom abundance, and a marked transition from diatoms comprising <10% of all eukaryotes prior to ~14.5 ka, to ~50% after this time, ie. following Meltwater Pulse 1A, alongside a composition change from sea-ice to open-ocean species.

Our study demonstrates that sedaDNA tools can be expanded to hundreds of thousands of years, opening the pathway to the study of ecosystem-wide marine shifts and paleo-productivity phases throughout multiple glacial-interglacial cycles.

…Sedimentary ancient DNA (sedaDNA) analysis studies ancient genetic signals preserved in sediments. Because genetic traces of all organisms, fossilizing and soft-bodied, can potentially be preserved in sediment records, the analysis of sedaDNA holds enormous potential to go beyond standard environmental proxies and allow reconstruction of entire ecosystems^5,6. Yet, the recovery of sedaDNA is complicated, as only trace-amounts of DNA are preserved and they are fragmented and degraded, which makes sedaDNA prone to contamination from modern environmental DNA^5,7. Recent improvements in sedaDNA techniques, including in anti-contamination measures during field work, laboratory work, and the use of bioinformatic DNA damage analysis, now permit authentication of sedaDNA detected in sediment samples^6,8,9,10,11. It is yet to be determined, however, how far back in time marine organisms can be detected using sedaDNA tools. So far, the oldest authenticated sedaDNA is from ~400,000-year-old terrestrial (cave) sediments¹², and ~650,000-year-old subarctic permafrost deposits¹³. In polar marine ecosystems, eukaryote sedaDNA has been recovered from up to ~140,000-year-old sediments in the Arctic^14,15,16 and <25,000-year-old sediments in the Antarctic⁷. Deep polar marine environments are ideal locations for sedaDNA research because of favourable DNA preservation^14,15. They feature constantly low temperatures (~0℃) and low oxygen (~5 mL L−1), and UV radiation is absent^17,18,19.

See Also:

• Genome-scale sequencing and analysis of human, wolf and bison DNA from 25,000 year-old sediment

• Million-year-old DNA sheds light on the genomic history of mammoths

• Measuring biodiversity from DNA in the air

• Atribacteria reproducing over millions of years in the Atlantic abyssal subseafloor

• Unearthing Neanderthal population history using nuclear and mitochondrial DNA from cave sediments

• Revival and Identification of Bacterial Spores in 25 to 40-Million-Year-Old Dominican Amber

• Ancient Human Genomics: The First Decade