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Genomic Clues to DNA Treasure Sometimes Lead Nowhere

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Science  10 Jul 2009:
Vol. 325, Issue 5937, pp. 142-143
DOI: 10.1126/science.325_142

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Summary

When a gene works, evolution holds on to it, keeping its sequence intact even as bases around it change over time. Genome researchers had come to depend on this conservation to steer them to critical regions in the genome: If a stretch of DNA remains unchanged across different species, that DNA is probably performing a vital function. But a growing number of examples show that not all conserved sequences are important and, worse, that not all important sequences are conserved. That second observation—which would have been considered heresy until about a decade ago—means that researchers who had typically relied on conservation to guide them could have missed critical genes or unknown regulatory regions. But even as they scramble to understand how the "conservation equals function" rule has failed them, they are uncovering profound new subtleties in how genes are controlled and how they adapt during evolution.