Reconstruction of genome-wide methylation maps – University of Copenhagen

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06 July 2015

Reconstruction of genome-wide methylation maps

Last year, a group of researchers at the Centre for GeoGenetics discovered that ancient epigenetic information could be extracted from next-generation sequencing data (Pedersen et al. Genome Research 2014). This information is essential given its prominent role in the regulation of gene expression and its increasingly recognized importance in the development of human diseases and cancer.

The methods developed in 2014 leveraged on the many chemical reactions that take place post-mortem, degrading DNA and even changing the composition of nucleotidic bases, to reconstruct genome-wide nucleosome and methylation maps. The 2014 study was led by Ludovic Orlando.

Great performance on permafrost samples

A group of researchers at CGG have now investigated the potential of more direct methods to reconstruct genome-wide methylation maps. The new method exploits the molecular affinity between Methyl-Binding Domains and methylated CpGs, which represents 70-80% of the total number of methylated epialleles in our genome. Rather than sequencing all the DNA extracted at random, the method preferentially selects methylated fragments, revealing whole methylation maps post-sequencing.

The authors show great performance for the method on DNA extracts showing minimal DNA degradation, such as those preserved in permafrost regions. However, they report limited success for the most ancient and damaged specimens investigated. The method, thus, seems appropriate to only reconstruct the most recent changes in our epigenome that have probably accompanied the industrial revolution and historical changes in lifestyle. The new study was led by Andaine Seguin-Orlando and Cristina Gamba.

The article was published in Scientific Reports on July 2nd 2015.