Beyond DNA changes in primate evolution
The EU-funded PRIMATE_REG_EVOL (A comparative genomic study of the contribution of epigenetic mechanisms to regulatory evolution in primates) project focused on the role of epigenetics in primate evolution. Involving chemical reactions that are not the result of changes in the DNA, the researchers studied epigenetic changes in five tissues from humans, chimpanzees and rhesus macaque monkeys. Regulatory mechanisms as a result of DNA methylation bring about differential regulatory systems. At the end of the project, the researchers expect to have a full set of gene expression data from the five tissues in the three primates. The result will be an opportunity to explore the conserved differences as well as the genes and pathways that have changed as a result of natural selection. To monitor methylation status of four tissues (heart, kidney, liver and lung) in the three primates, the scientists used whole-genome bisulphite conversion. The process converts the base cytosine into uracil but leaves the methylated cytosine untouched. High-throughput sequencing in the three primates was then analysed to reveal species differences. Using RNA sequencing, the project has also collected gene expression profiles to scan for genes and biochemical cascades that have changed through evolution. Integration and analysis of the data sets revealed genome features where methylation changes are associated with expression changes. A statistical model researchers developed can calculate the proportion of variation in gene expression levels across tissues and species that can be explained by changes in methylation. Data amassed and analysed during the PRIMATE_REG_EVOL project has determined the molecular mechanisms that explain in part the regulatory differences between species. This has enhanced our understanding of evolution on the basis of gene regulation changes. Overall, this research could serve as a platform to study evolution at the molecular level in general.
