Magazine article Science & Spirit

Debunking Genetic Junk

Magazine article Science & Spirit

Debunking Genetic Junk

Article excerpt

"junk DNA." For years, it's been scientists' favored label for the seemingly functionless genes that do not contain protein-coding instructions. But recently, there's been a growing movement to debunk the junk.

In a recent issue of the journal Nature, University of California, San Diego biology professor Peter Andolfatto reported that noncoding DNA regions play an important role in maintaining an organism's genetic integrity.

In his study of genes from the fruit fly Drosophila melanogaster, Andolfatto discovered that one scientist's trash is another scientist's treasure. It turns out that natural selection, the evolutionary process that preferentially leads to organism survival, strongly affects regions of "junk" DNA.

In Drosophila melanogaster, noncoding DNA accounts for about eighty percent of the fly's total genome. Using an advanced population genetics approach, Andolfatto found these regions evolve more slowly than natural selection pressures would suggest.

"This pattern most likely reflects resistance to the incorporation of new mutations," he explained. "In fact, forty to seventy percent of new mutations that arise in noncoding DNA fail to be incorporated by this species, which suggests that these non-protein-coding regions are not 'junk,' but are somehow functionally important to the organism."

Noncoding DNA isn't the only thing genetics researchers once wrote off. While DNA contains the instructions for growth and development, RNA translates these instructions into proteins--cellular building blocks. …

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