The Case for CRISPR

When some people hear the term “selective breeding,” they assume it’s a fairly recent technology. Well, they would be off just a little bit — by about 12,000 years, to be precise. Practices such as breeding crops for desirable traits are almost as old as agriculture itself. Fast-forward to barely 150 years ago when we first began to understand genetics. Our working knowledge of DNA dates back only to the mid-20th century, and only then did genetic engineering get more sophisticated.

Just a few decades removed, the intersection between science and food is at perhaps the most exciting place yet. With the rise of “big data,” we are beginning to see the connection between genetics and the food we eat, also called nutrigenomics. And now we stand on the cusp of a potentially revolutionary technology called “CRISPR.” It might sound like a drawer in your refrigerator, but it’s actually a tool that could bring enormous benefits to the food system. 

What is CRISPR? 

Before we dive into CRISPR, trust us, you may want to be sure to brush up on some basic genetics and biology so that the terms we use aren’t too foreign. CRISPR is one of many methods to alter the genetic information in the cells of living things — plants, fruits, vegetables, etc. That genetic information is called DNA, which are chains of molecular building blocks called nucleotides. DNA can produce proteins that define what an organism’s cells do or don’t do — kind of like how software controls the operation of a computer.

Snippets or “sequences” of DNA called genes, pass down inherited traits over generations, tend to be stable, changing only slightly over time as organisms evolve and adapt to new conditions. Sometimes these changes are visible, such as the color of a flower, and other times they are less apparent.

So how does DNA actually cause these changes? You can think of the nucleotides — those molecular building blocks we mentioned — being like letters, while DNA is like a word made from those letters, with proteins being similar to a grouping of words into sentences.  To alter the sentence (which is your ultimate goal), you need to alter the words. And to change the words, you need to modify the letters.

That’s where CRISPR comes in. CRISPR, an acronym for the much more cumbersome “Clustered Regularly Interspaced Short Palindromic Repeats,” involves a process that directly targets and alters specific regions of DNA. For all of those genetic letters and words and sentences, part of the CRISPR system includes a helper called CRISPR-associated protein 9 (Cas9). With the help of the Cas protein, you can think of the CRISPR system like a pair of molecular scissors that snip and rearrange the pieces of DNA at a specific location that will yield a change the DNA nucleotide sequences.

We also like this other analogy from Alison Van Eenennaam, PhD, a professor at University of California, Davis, describing CRISPR: “It's editing. It's like going into a Word document and basically replacing one letter, maybe that instead of 'wind,' you want it to say 'wine,'" she says.

As we discussed in our Genetics 101 article, once the DNA sequence is changed, the protein production of the cell is also changed. (If we’re throwing too many “food nerd” terms at you all at once, don’t worry! You can check our genetics glossary below.)

How does CRISPR work?

Scientists in 1987 noticed repeating bits of a short nucleotide sequence in E. coli DNA, which they named CRISPR, but they didn’t know what function it served.

Later, in another strain of bacteria, CRISPR was found to act like a GPS to guide those Cas9 scissors, to mix a metaphor. They were able to identify a harmful virus, cut up the viral DNA and store pieces within its own DNA that could then be matched up against future threats. But this GPS didn’t just work against viruses; it could identify and alter any DNA (with a target sequence).

This “destination-fixed” cutting of DNA is an extremely accurate and efficient way to obtain specific traits or characteristics, much more so than other methods of genetic engineering. It’s such an ingeniously basic process that it’s a wonder we’re only now beginning to understand it. Just how basic? There are even home-brew CRISPR kits springing up that allow anyone to “hack DNA.”

What does CRISPR mean for our food system?

It’s hard to overstate just how excited researchers and other experts are about the possible applications of CRISPR. From this one seemingly simple pair of scissors, they envision not just the prevention and treatment of serious and even deadly diseases but also a bonanza for our food system.

CRISPR technology could one day improve food safety, increasing the shelf life of perishable foods and developing foods with enhanced nutrition. It shows enormous promise for agricultural and crop trait enhancement, livestock breeding and the elimination of antibiotic resistance. It has already been used to create a better-tasting tomato, mildew-resistant wheat and drought-resistant corn.

Some of the potential uses of CRISPR can even address the scourge of food waste. Take mushrooms, for instance. A natural enzyme can cause mushrooms to turn brown, which many people mistake for spoilage. A non-browning mushroom, on the other hand, would help prevent us from needlessly throwing out perfectly good food.

Is it regulated?

Given that CRISPR tools are used to make changes in the genome of an organism, it is natural to wonder if these products will be regulated and how? The short answer is, “It depends.”  

Not all foods improved by the application of CRISPR tools will require regulation. The USDA’s Animal and Plant Health Inspection Service (APHIS) currently regulates certain genetically engineered (GE) organisms or genetically modified foods that may present a plant health risk.  So in cases where the DNA has been changed, but the change does not harm the plant or make it more susceptible to pests, USDA does not require additional regulation of that plant or food.

In the case of that non-browning mushroom, the USDA has determined that it does not require additional regulations to be grown. However, it may still undergo review by the U.S. Food and Drug Administration, and some regulators outside the United States are still trying to decide how to regulate foods developed using these tools.

By the way, we should note that CRISPR is not transgenic — i.e. a method that transfers genes from one species into another — which has long been the subject of a heated but often misinformed debate, as well as regulatory delays.

Final thoughts

While publicists and headline-writers might be known for their hyperbole, scientists are typically thought of as a much more sober crew. So it’s their enthusiasm for CRISPR and belief in its potential that set it apart from other technologies that started out rich in promise but ended up flashes in the pan. No technology is a panacea. But few of them are looked upon with the kind of awe at the elegant and transformational power of CRISPR.

Way back in 10,000 BCE, humans first began to farm and employ primitive techniques of genetic modification to feed and nourish themselves. It would take many millennia for us to begin understanding the science behind those natural processes but only a matter of years to harness and unleash them at the molecular level.

We wonder what those ancient ancestors toiling in the fields would think if they had known about these mind-boggling advances.

This blog post includes contributions by Tamika Sims, Megan Meyer and Matt Raymond.

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