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DNA methylation is one of the most studied epigenetic modifications, yet its ancestral function in animals and its capacity for transgenerational inheritance remain incompletely understood. While mammals undergo extensive epigenetic reprogramming after fertilization—largely preventing the transmission of acquired methylation states across generations—this resetting mechanism appears to be absent in invertebrates, raising questions about how methylation patterns are maintained and what consequences arise when they are disrupted.
To explore what happens when epigenetic patterns are disrupted, scientists from Queen Mary University experimentally removed DNA methylation in the sea anemone Nematostella vectensis. The results were unexpected: animals developed normally despite losing most of their DNA methylation. Rather than causing major defects in gene regulation, the loss of methylation mainly unleashed hidden "jumping genes"—also called "selfish genes"—embedded within active genes. Left unchecked, these genetic parasites can insert themselves into important genes and regulatory regions, potentially disrupting normal development and threatening genome stability.
The study also revealed that because sea anemones lack the extensive epigenetic resetting that occurs after fertilization in mammals, some abnormal methylation states persisted in offspring. "These inherited epigenetic changes altered how genes are switched on in the next generation, demonstrating that experimentally induced epigenetic variation can be transmitted across generations in an animal," said Alex de Mendoza, senior author of the study published in Nature Ecology & Evolution.
The findings suggest that the ancestral role of DNA methylation in animals was not primarily to regulate gene expression, but to protect active genes from disruptive jumping genes. In mammals, this same molecular system has since taken on a broader range of functions, including regulating development and silencing one of the two X chromosomes in females.
The work also shows how incomplete epigenetic resetting can allow heritable variation to persist across generations without requiring any changes to the genetic code itself—potentially providing raw material for evolutionary change. In doing so, the study offers a window into the evolutionary origins of important regulatory systems, and demonstrates how more ancient mechanisms of gene regulation can transmit information through generations.
To explore what happens when epigenetic patterns are disrupted, scientists from Queen Mary University experimentally removed DNA methylation in the sea anemone Nematostella vectensis. The results were unexpected: animals developed normally despite losing most of their DNA methylation. Rather than causing major defects in gene regulation, the loss of methylation mainly unleashed hidden "jumping genes"—also called "selfish genes"—embedded within active genes. Left unchecked, these genetic parasites can insert themselves into important genes and regulatory regions, potentially disrupting normal development and threatening genome stability.
The study also revealed that because sea anemones lack the extensive epigenetic resetting that occurs after fertilization in mammals, some abnormal methylation states persisted in offspring. "These inherited epigenetic changes altered how genes are switched on in the next generation, demonstrating that experimentally induced epigenetic variation can be transmitted across generations in an animal," said Alex de Mendoza, senior author of the study published in Nature Ecology & Evolution.
The findings suggest that the ancestral role of DNA methylation in animals was not primarily to regulate gene expression, but to protect active genes from disruptive jumping genes. In mammals, this same molecular system has since taken on a broader range of functions, including regulating development and silencing one of the two X chromosomes in females.
The work also shows how incomplete epigenetic resetting can allow heritable variation to persist across generations without requiring any changes to the genetic code itself—potentially providing raw material for evolutionary change. In doing so, the study offers a window into the evolutionary origins of important regulatory systems, and demonstrates how more ancient mechanisms of gene regulation can transmit information through generations.