Cover Story

Debunking junk

"Debunking junk" Continued...

Issue: "Reassessing the genome," Oct. 6, 2012

As you might expect, the regulatory switches are often found right next to the genes they control. But sometimes they’re found hundreds of thousands of base pairs away. Which brings us to yet another layer of complexity—the three-dimensional shape of DNA.

Like a chain coiled in a bucket, DNA is tightly folded against itself, so segments (or links) that would otherwise be far apart lie close together. The precise folding of DNA means that ENCODE researchers often found regulatory switches actually touching the genes they control, even though they’re linearly distant. It’s a surprising new way to think about the importance of DNA’s shape.

moran.jpg“The creationists are going to love this,” complained LARRY MORAN. “This is going to make my life very complicated.” (Zuma Press/Newscom)

Together, these interdependent mechanisms make a case against Darwinian evolution, said Georgia Purdom, a genetics researcher at the creationist organization Answers in Genesis. Evolving an existing organ into something different would require a genetic choreography of mutations: “It’s not just changing one gene. You have to change not only that gene, but the regulation of that gene, and other genes that are involved ... in that particular biological pathway.”

Some DNA stretches may still appear inactive, but Purdom thinks they could contain segments that have lost function since creation—or that are only active at certain times, like during an embryo’s development.

Meyer of the Discovery Institute said the hierarchical layers of information controlling the genome have a particular benefit: They allow for the efficient storage of vast amounts of genetic information. “The functions they perform are so strikingly similar to functions that we’ve designed to solve similar information and storage problems in high tech digital computers.”

Meyer noted we still don’t understand all of the ways cells communicate, such as during the development of an animal embryo in utero. Some information needed for the animal’s growth is apparently conveyed through the three-dimensional structure of the embryo itself.

“It’s layers within layers of complexity. That’s what’s being revealed in biology. It’s mind-boggling.”

ENCODE has given us a glimpse of the complexity. It has hacked a path into the genetic jungle, and planted a few guideposts that will accelerate future discoveries.

The United States may spend $123 million supporting the next phase of the ENCODE project, in which researchers will continue charting out DNA functions within various cell types. They’ll try to understand how gene regulation occurs over time, gaining a movie-like perspective. They’ll try to figure out how gene switches combine, telling cells what type of tissue to become, or influencing visible human traits like height and weight, aging, or diseases like Crohn’s.

“For centuries to come, biologists will be making fundamentally new discoveries about the features of living things,” predicted Wells. “But probably not if they begin by assuming that those features are junk.

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National Human Genome Research Institute/AP

Daniel James Devine
Daniel James Devine

Daniel is a reporter for WORLD who covers science, technology, and other topics in the Midwest from his home base in Indiana. Follow Daniel on Twitter @DanJamDevine.

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