Methylation of DNA, in which a methyl group is covalently bonded to a cytosine base, is an epigenetic mark that is widespread throughout the tree of life, from bacteria to humans. However, there are some branches of the tree in which DNA methylation is mysteriously absent. Until the publication of two studies in Genome Biology’s epigenomics issue, nematodes and ciliates were thought to be among these DNA methylation-free phyla. But multiple independent assay methods in the Genome Biology articles confirmed its presence in the nematode Trichinella spiralis and in the ciliate Oxytricha trifallax.
How surprising are these findings? Are more surprises yet to come? How will the two studies shape future directions for DNA methylation research? To answer these questions, Genome Biology Senior Editor Naomi Attar (@naomiattar) spoke to Soojin Yi, from the Georgia Institute of Technology, who is one of the world’s foremost experts on the evolutionary biology of DNA methylation.
Yi obtained her PhD in ecology and evolution at the University of Chicago, USA, under the supervision of evolutionary biologist Brian Charlesworth. She stayed on at the University of Chicago to undergo her postdoctoral training before being appointed associate professor at the Georgia Institute of Technology, USA, where she currently investigates the genetic basis of naturally occurring variation within and between species. In response to the novel findings of DNA methylation in nematodes and ciliates, Yi wrote a Research Highlight for Genome Biology as a commentary providing more background information on these discoveries.
Studies reporting such unexpected biological findings warrant critical scrutiny of the data upon which their conclusions are based. To find out more about how the scientists behind the T. spiralis and O. trifallax articles set out to make all their raw data fully open, see Genome Biology’s blog post on ‘Rebel worms and mixed-up ciliates’. In recognition of these efforts, Fei Gao, first author of the T. spiralis article, recently accepted BioMed Central’s Open Data award.