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Potential risks that you do not know about the new transgenic techniques

Potential risks that you do not know about the new transgenic techniques

These are personal choices, but there are some risk assessments that we have to do as a class. The changes we make to the DNA of plants, animals and humans can be transmitted ad infinitum, fundamentally altering the flora and fauna of the Earth. The use of genetic modification in food crops and in medicine also raises debates about health risks.

Just as much-used genetic modification technology evolves rapidly, so does the conversation about acceptable risk. The new techniques, widely known as "gene editing," are poised to take over the US food and agriculture industry. About 5% of the US canola on the market is already manufactured using these techniques. And scientists in China, the UK and Sweden are testing them on human embryos, something never done with older techniques.

They consider it the lowest risk way to manipulate DNA and reap all the benefits, such as creating mushrooms that do not turn brown or soybean oil that is lower in trans fat, or in the case of humans repairing genes that cause diseases.

But some scientists and consumer advocates who have long been concerned about genetically modified organisms (GMOs) are equally concerned about these new types of altered organisms.

Older technologies involve inserting genes from foreign organisms into a plant's DNA to give it a desired trait. For example, a gene from a bacterium was inserted into a soybean plant to make it resistant to herbicides.

The process of "inserting" genes is imprecise; One method involves attaching the desired genes to tiny metal balls and firing them into plant cells.

New technologies, on the other hand, use molecular tools that are designed to specifically target the desired part of DNA. The use of genes from other species is not required but they can simply cut an unwanted gene or make other rearrangements to the genome.

On the other hand, new technologies use molecular tools that are designed to specifically target the desired part of DNA.

Biotech companies use these technologies in the hope that it will make all the difference for consumers who are suspicious of so-called "frankenfoods." GMOs made from a DNA compound from multiple species are unlikely to occur in nature.

Advanced precision is one of the greatest assets of the new techniques, as they reduce the risk of making additional unintended changes to the genome. But studies by researchers in Germany, Switzerland, and China, among others, have shown that new techniques can still have off-target effects.

According to Guillermo Montoya, a biologist at the University of Copenhagen, it is difficult to detect these unwanted effects. Sequencing the entire genome to look for problems is expensive and technically difficult, he explained by email, and it is especially difficult to find off-target effects that occur less frequently.

Current detection methods rely on probability, not 100% certainty. For example, a method may have a high chance of detecting an off-target effect that happens about 40% of the time, but has a small chance of finding one that only happens 10% of the time.

In a 2016 study published in the journal Bioessays, Montoya wrote: "Talen and Crispr-Cas9" [two of the new techniques] are widely used in genome editing. However, none of them have a perfect DNA recognition specialty, so breaks can occur at other DNA sites in the genome.

"This off-target effect can introduce unwanted changes in genome sequences with unpredictable consequences for cells, organs, organisms and even environments," he explained.

Shengdar Q. Tsai, a genetic engineer at St. Jude’s Children's Research Hospital in Memphis, Tennessee, has also looked at the problem of off-target low-frequency effects.

In 2014, in an article for the peer-reviewed journal Cell Stem Cell, he wrote: “Clearly, a balanced across the genome method is also sensitive enough to identify even the lowest frequency required outside of target effects. … This is critically important because unwanted modifications in cell populations can lead to unexpected functional consequences in both research and therapeutic contexts, where functional consequences even in low-frequency mutations can be of great concern ” .

Dan Voytas, one of the creators of Talen, said that he has not found any unwanted changes in food crops he has worked on as chief scientist at the Calyxt biotech company. The company has developed several food crops that it hopes to start selling to farmers in the coming years, including wheat with reduced gluten and a canola low in saturated fat.

After designing molecular tools to target and extract particular genes, Voytas' team examined selected parts of the genome for off-target effects, in places where molecular tools could easily get confused in target areas.

His team hasn't found any off-target effects at these locations, but they haven't tested the entire DNA either.

Researchers at the University of Osnabrück in Germany also reported that off-target effects are rare with Talen, and much less prone to off-target effects than Crispr-Cas9. But they did note in their March article in the journal Plant Methods that using Talen to create an eggplant (Arabidopsis) plant resulted in the omission of three different genes than intended. This "seemed to have happened spontaneously," they wrote.

Some food products are being made with Crispr-Cas9, such as a DuPont sweet corn that is expected to be available to US growers within the next five years.

Agrochemical giant Monsanto announced in January that it will use Crispr-Cas9 and its sister technology, Crispr-Cpf1, to create new crops.

Cibus, a California-based biotech company, uses another new technique called the Rapid Trait Development System. Cibus was the first company to launch a product using one of these new techniques commercially; in 2014 they started selling their SU canola seeds to farmers.

"It is difficult to say that there is zero risk"

While there are risks to these new technologies, there are also risks to technologies that have long been used in agriculture, said Richard Amasino, a professor of biochemistry and genetics at the University of Wisconsin-Madison who attended a committee assembled by the Academy. National Science (NAS) to assess the future of genetically modified crops.

“If you ask, 'Could something harmful be created?', Well, yes, any process that results in DNA change including conventional phyto-breeding could in principle create something harmful,” he said.

He explained that even conventional enhancement of desired traits can create unwanted effects, such as increased allergenicity or toxicity. "It's hard to say there is no risk at all," he said.

But Amasino thinks that the degree of precision makes these new techniques safe in a broad sense and preferable to previous methods. He thinks the risk is low and the potential benefits are high.

Voytas also commented on the benefits: “Almost all the products we are making have a direct benefit to the consumer: a healthier soybean oil…, a lower gluten and higher fiber wheat product. We hope that the consumer will see that biotechnology can be used to satisfy consumer needs and perhaps influence their acceptance. Whereas in the past, agricultural biotechnology has greatly benefited the farmer and the production system - [creating traits like] tolerance to herbicides and resistance to pathogens.

Megan Hochstrasser earned her Ph.D. in Research from Crispr in the lab of its creator, Jennifer Doudna. Hochstrasser explained the difference between muta genesis, an older and more commonly used GM technique, and Crispr-Cas9. She said it is comparable to the difference between Boggle and Scrabble.

“Muta genesis means taking existing DNA and shaking it up almost like a Boggle game, where you end up getting letters and maybe making a good word, maybe not. Maybe you have changes somewhere else that you don't know about.

She continued: “Crispr, I'd say it's closer to Scrabble… where you can choose the exact sequence of letters you want. So even if there are occasional off-target effects, it's still monumentally different from previous approaches. "

Since all previous breeding methods from selective breeding to genetic engineering have been about DNA change and have had unwanted effects, Hochstrasser feels that Crispr is preferable for use in agriculture because it is more accurate.

Its use in humans worries him more. He worries that people will even use it to enhance or create aesthetically pleasing features instead of preventing disease.

Another concern raised by many is the increased risk of off-target effect if these techniques are combined, if scientists try to create more than one change in the genome. For example, the 2017 NAS report Preparedness for Future Biotech Products states: “The magnitude of the risk could change, as the synergistic effects of multiple genetic changes could lead to unwanted effects on the biochemistry of crops (which affects nutrients, immunological, phytohormonal, or toxic) ”.

This report also said that given the risk assessments of biotech products using qualitative language without probabilities of risk, NAS was unable to quantify the risks. He suggests that evaluations should start to expose these probabilities, for example how much more likely these random effects are to occur with Talen and similar technologies with random mutations in nature.

The novelty of these techniques has also raised concerns. A joint statement by Greenpeace and other advocacy groups issued in February said: "Since many of the techniques are new, it has not yet been possible to fully assess the potential for adverse effects."

Megan Westgate, executive director of the Non-GMO Project, provides verification and labeling for non-GMO products, said by email: “GMOs, including products from these new technologies, have not been adequately tested, there are no long feeding studies. term that have been conducted ”.

Aside from the risks directly related to off-target and human health effects, the USDA organic council has discussed side effects of concern.

In a recommendation published in November last year, he listed some problems with GMOs in general, noting that these concerns also apply to the new breed of GM crops: the altered nutritional profiles of GM crops, the displacement of small farmers, and the decrease in soil diversity and fertility due to the use of herbicides.

The Epoch Times


Video: What Is a Genetically Modified Food? - Instant Egghead #45 (July 2021).