Preserved fossil DNA in the ice – University of Copenhagen

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Centre for Ice and Climate > Research > Biology and ice > Reconstruction of past ecosystems and climate using fossil DNA > Preserved fossil DNA i...

Preserved fossil DNA in the ice

Before the drilling of deep ice cores took place, fossil finds from ice-free areas supplied material to describe past warm climatic periods. Ice cores drilled in Greenland and Antarctica now provide access to frozen molecular remnants – “fossil” DNA – from the basal ice, which can be dated hundreds of thousands of years back in time.

The DNA molecules are degraded and fragmented with time since the time of incorporation to the soil of the past ecosystems. The DNA comes from the organisms that once lived in the area that is today ice covered. By sensitive DNA techniques the preserved DNA molecules can be analyzed and provide new data informative about past climate periods just prior to ice coverage.

By applying genetic methods to the basal ice from the deep ice cores it is possible, through “fossil” DNA from prehistoric organisms, to gain insight into the ecosystems of previous warm periods. These warm period ecosystems are interesting as it gives researchers the opportunity to compare current climate change with changes that occurred more than 100,000 years ago. 

”Fossil” DNA should not be seen as a statically preserved molecule. From the moment an organism dies, its DNA decays and fragments. In frozen conditions the decomposition process goes slowly, while DNA-decomposing enzymes and chemical processes work much faster in warm conditions. If the DNA is bound to soil particles in dry or cold ice, or permafrost, the decomposing effect of enzymes will be lessened because the charges of the soil particles may have a stabilizing and protectingeffect on the DNA.

The ”fossil” preserved DNA consists of remains of the genomes of dead organisms, which can be propagated and studied for both prehistoric climatic conditions, biodiversity and the composition of ecosystems. 

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- Reconstruction of past ecosystems and climate using fossil DNA
- Fossil DNA's potential and limitations
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