Genome complexity: epigenetic mutation rate (Introduction)

by David Turell , Tuesday, May 12, 2015, 14:27 (3265 days ago) @ David Turell

In thale cress, slow enough over generations for natural selection to act, but much faster than sequence mutation. Epigenetics is methylation, not base change, with additions and subtractions over time.-http://www.the-scientist.com//?articles.view/articleNo/42948/title/Estimating-Epigenetic-Mutation-Rates/-"Methylation on the DNA base cytosine can regulate the expression of genes and transposable elements in organisms including the model plant A. thaliana, in which 14 percent of the cytosines are methylated. While some methylation marks are maintained from generation to generation in A. thaliana, others are rapidly acquired or lost over time.-"To understand if these methylation changes can be subject to natural selection, researchers from the University of Groningen in the Netherlands, the University of Georgia, and the University of Minnesota mapped cytosine methylation at single-base resolution over as many as 32 generations of three different lines of the plant. The scientists then designed a model to estimate how quickly methylation at a particular location was gained or lost between generations and fit the model to their experimental data on the known locations of the methylated cytosines. They found that methylation changes are common throughout the genome. Some regions were more likely to lose methylation than to gain it, while others, such as transposable elements, were as much as 30 times more likely to gain methylation than lose it.-“'Epigenetic mutations are about 100,000 times more likely than DNA sequence mutations,” study coauthor Frank Johannes of Groningen said in a statement. Importantly, however, the epigenetic mutation rate is still low enough to be subject to natural selection, the authors wrote in their paper."