In DepthGenetics

Mysterious unchanging DNA finds a purpose in life

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Science  02 Jun 2017:
Vol. 356, Issue 6341, pp. 892
DOI: 10.1126/science.356.6341.892

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Genome scientists have solved a long-standing mystery about ultraconserved regions of our genome. Computational scientists first identified these anomalous stretches of DNA in 2004, by comparing the genomes of diverse mammals, finding 481 genome segments, 200 to more than 700 bases long, that were 100% identical in humans, rats, and mice. The conservation suggested these segments were essential to life, but 3 years later, another team knocked out these regions and found no effect on the mice they created. Now, researchers have tried again, sometimes knocking out two such regions at once near a key gene in the developing brain. The mice developed as in the earlier experiment, but did have fewer nerve cells or a smaller hippocampus, changes that in the wild may have doomed the rodents. Other researchers are quite pleased to learn that these regions really do have a function.