Diving Deep into Global 5-methylcytosine DNA Methylation Across the Subclass Octocorallia (Cnidaria, Anthozoa)

DNA methylation is an epigenetic property in which a methyl group is attached to a DNA base. This addition can change the gene expression of an organism without changing its underlying genetic sequence. A change in DNA methylation can help an organism adapt to novel environments rapidly. This is especially important in a variable environment such as the shallow ocean. DNA methylation has not yet been studied in Octocorallia (Cnidaria, Anthozoa), colonial animals that create structural habitat for other organisms and which live from littoral to hadal depths and from tropical to polar waters. To determine if octocoral DNA is methylated, we conducted an ELISA-like method to measure the percentage of global 5-methylcytosine (5mC) methylation. Species from 13 families representing two of the three taxonomic orders were analyzed to establish the range of variation in the global 5mC methylation across the subclass. We evaluated species from both shallow and deep-sea depths to determine if there is a difference in global 5mC methylation between the two environments. We demonstrated that octocorals possess DNA methylation and there is variation both within and among species. The average percent of global 5mC DNA methylation in the octocorals we analyzed was 1.44%, with a wide range from non-detectable to approximately 5%.