Method shows how precisely gene expression signals are copied in DNA replication

“A group of University of Washington researchers has devised a method that combines DNA sampling and mathematical modeling to find out how accurately methylation patterns are copied during DNA replication. That could pave the way for understanding the role methylation plays in normal gene expression and how it factors in the development of human disease.”

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“Methylation typically passes from genes in a DNA strand to the same genes in a daughter strand created during DNA replication. The new technique allows researchers to examine how faithfully this "maintenance" methylation is carried out across generations and how consistently it occurs on the same gene sequence, said Brooks Miner, a UW research scientist in biology and a co-author of the paper.

But DNA molecules also can undergo what is called "de novo," or new, methylation in which a methyl group shows up on a DNA strand at a place where it did not appear before. That could change how that particular gene sequence is expressed.”
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“In the past, researchers could look at only one strand of DNA at a time and so could not conduct a side-by-side comparison of where methylation was occurring. An earlier paper from the same research group, led by Charles Laird, a UW biology professor, introduced a molecular method to look at both DNA strands together and observe methylation differences between them.”