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takyon [soylentnews.org] writes:

'Junk DNA' may help yeast survive stress [sciencemag.org]

Like deleted scenes snipped out of a movie, some sequences in our genes end up on the cutting-room floor, and cells don't use them to make proteins. Now, two studies find that these segments, known as introns, help yeast survive during hard times. The research uncovers another possible function for a type of DNA that scientists once thought was useless.

"They are very strong, very convincing, and very exciting results," says evolutionary molecular biologist Scott Roy of San Francisco State University in California, who wasn't connected to the studies. The research "opens a whole new paradigm of what introns could be doing." It also answers the long-standing question of why yeast has kept what was formerly considered "junk DNA," says yeast microbiologist Guillaume Chanfreau of the University of California, Los Angeles.

[...] [Researchers] typically haven't looked at yeast under conditions it would face in the wild, where it could endure periods of food scarcity that don't occur in the lab. To determine what happens during deprivation, RNA biologist Sherif Abou Elela of the University of Sherbrooke in Canada and colleagues systematically deleted introns from yeast, producing hundreds of strains, each of which was missing all of the introns from one gene. The researchers then grew combinations of these modified strains alongside normal fungi.

When food was scarce, most of the intron-lacking strains rapidly died out [doi.org] [DOI: 10.1038/s41586-018-0859-7], the team reports today in Nature. They couldn't compete with normal yeast. However, in cultures with more nutrients, the altered yeast had the advantage. "If you are in good times, it's a burden" to have introns, Abou Elela says. "In bad times, it's beneficial."

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