Investigating the Preservation Process of DNA in the Cold and Arid Paleoshores of the Antarctic Untersee Oasis

The perennially frozen Lake Untersee and its paleoshores make up the Untersee Oasis, located in Eastern Antarctica, where the mean annual temperature is -10C [1]. The lake itself contains actively growing, modern microbial mats, and the cold, arid paleoshores of Lake Untersee are home to dry paleomats, which are remnants of microbial mats that lived within the lake hundreds to thousands of years ago. The combination of the modern and desiccated paleomats provide a unique sample set for the study of biosignature preservation in cold, dry conditions. Recent studies of biomarker preservation have been focused on lipids and other fatty acids which are well preserved in these cold and dry conditions [2]. However, in this study, we focus on the preservation of DNA, a much more information rich molecule. I have analyzed and sequenced DNA extracted from both paleomats found in the shores and modern mats within the lake. Using metagenomics, I study the changes in community structure and composition through time. I study the chemical changes that DNA undergoes through the early stages of diagenesis during which most degradation occurs. Previous studies found the chemical changes to include strand break and deamination damage to bases such as cytosine, adenine and guanine [3]. Here, I assess the DNA quality in the mats by studying the changes in strand length through time. I use Uracil N-Glycosylase treatments to study deamination in the samples. [1] Andersen, T., Journal of Applied Meteorology and Climatology, 2015; [2] Wilhelm, M. B., Organic geochemistry, 2017; [3] Shapiro, B., Science, 2014