Remove the Identical Stretches of DNA Found in Mice, Rats, and Humans and What Happens?

Posted on November 13, 2007  Comments (0)

A Real Genetic Headscratcher by Derek Lowe:

As you root through genomic sequences – and there are more and more of them to root through these days – you come across some stretches of DNA that hardly seem to vary at all. The hard-core “ultraconserved” parts, first identified in 2004, are absolutely identical between mice, rats, and humans.

Even important enzyme sequences vary a bit among the three species, so what could these pristine stretches (some of which are hundreds of base pairs long) be used for? The assumption, naturally, has been that whatever it is, it must be mighty important, but if we’re going to be scientists, we can’t just go around assuming that what we think must be right. A team at Lawrence Berkeley and the DOE put things to the test recently by identifying four of the ultraconserved elements that all seem to be located next to critical genes – and deleting them.

The knockout mice turned out to do something very surprising indeed. They were born normally, but then they grew up normally. When they reached adulthood, though, they were completely normal. Exhaustive biochemical and behavioral tests finally uncovered the truth: they’re basically indistinguishable from the wild type. Hey, I told you it was surprising. This must have been the last thing that the researchers expected.

What a great example of scientists at work. It will be interesting to see where this goes.

Related: Deletion of Ultraconserved Elements Yields Viable Mice (PLoS Biology) – Ultraconserved Elements in the Genome: Are They Indispensable?One Species’ Genome Discovered Inside Another’sOpossum Genome Shows Junk DNA is Not JunkNew Understanding of Human DNA

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