Animal IQ

Scientists Trimmed the Fat by Genetically Engineering Leaner Pigs

Hold the turkey bacon: researchers just used a gene editing tool to produce a new kind of pig with 24 percent less body fat than what you'd find in a normal pig. Utilizing CRISPR gene editing technology, scientists inserted a gene that helps pigs burn fat to stay warm. Mammals like mice and rats already regulate their body temperatures using this gene, but this little piggy missed out on that gene – until now. And the implications go a lot farther than the calorie count in your favorite pork plate.

Bacon-Wrapped Traits

So how did they do it? Researchers added the protein using CRISPR-Cas9, a gene-editing technology that allows scientists to make precision edits to any DNA, whether bacterial or human. Using CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats), scientists can cut, copy, and replace pieces of DNA and use it to their own ends, applying it to virtually any DNA they want – including the DNA in pigs.

In this particular case, the UCP1 mice protein was added to 2,553 pig embryos, and 12 low-fat male piglets were successfully birthed. Those piglets with a lower fat-to-weight ratio had a better ability to generate heat in cold temperatures, giving them a better shot at life thanks to their enhanced ability to protect themselves from dying of cold shock.

In the study published in Proceedings of the National Academy of Sciences (PNAS), researchers say the gene editing technique could lead to more efficient pork production, reduced costs for farmers, and healthier pigs. R. Michael Roberts, a professor in the department of animal sciences at the University of Missouri, told NPR that he doubts the Food and Drug Administration would approve a genetically modified pig for sale in the United States. But the FDA has approved genetically modified salmon, and more modifications could be in the making.

On the Curiosity Podcast, we talked to Dr. Sam Sternberg, a biochemist and expert in CRISPR gene editing technology, about CRISPR's current and future applications. "I think a lot of agricultural companies are going to very aggressively be using CRISPR for editing crops or editing livestock, either to provide benefits for farmers in terms of how they grow or being less reliant on certain pesticides, or also developing crops that might have traits that consumers will desire," he told us.

"There's a case of a mushroom that was edited with CRISPR so that it doesn't brown. So you can imagine mushrooms that can sit in your pantry for weeks and they're never going to go brown. There's a soybean oil that has a more favorable fat content, a potato that has lower levels of a neurotoxin when it gets fried... and these were edited not with CRISPR but with a different gene editing tool. But I think in the world of food production, there could be very major influences from CRISPR in gene editing."

When Pigs Fly

So what's next for CRISPR technology? "There are scientists that are using gene editing to make changes in Asian elephant DNA that make the Asian elephant genome look more like the wooly mammoth genome," Sternberg told us. "There's a legitimate hope by reputable scientists that we might one day be able to resurrect something akin to a wooly mammoth using a tool like gene editing. That's actually research being done." He went on to explain that China has been at the forefront of many early CRISPR experiments in embryos, but internationally, there are many challenges facing future applications of the technology.

"I think this research is happening in a lot of different places, and we'd like to have international consensus on how we'd like to proceed. But I think the reality is, different cultures, different value systems in other parts of the world, may be different than how it goes in the U.S.," he said.

The potential for CRISPR is huge: if scientists have the accuracy to replace just a few faulty genes, it might be possible to cure genetic disorders as serious as cystic fibrosis and Huntington's disease and as common as lactose intolerance and color-blindness. But first, political and regulatory hurdles need to be cleared.

"Part of the challenge is coming to some kind of agreement and preventing what one could imagine happening, which is 'something's not allowed here but it's allowed somewhere else,' and so consumers or parents and physicians go to other jurisdictions to access those treatments," Sternberg explained. "Stem cell tourism is definitely a problem. I think the concern about having overly restrictive regulations in the U.S. is that, are people just going to go elsewhere? Of course, that's not an argument to say let's do everything here."

To hear our full conversation with Dr. Sam Sternberg, an assistant professor in the Department of Biochemistry and Molecular Biophysics at Columbia University, listen to our full conversation on the Curiosity Podcast using the player below (or click here for the show notes).

Mice with green feet demonstrate CRISPR gene editing technology

How does CRISPR gene editing work?

Written by Cody Gough October 31, 2017

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