What Are GMOs?: GMOs Part I

Genetically Engineered Barley (USDA)

What Are GMOs?:  GMOs Part I

The following excerpt is from the Penn State Ag Science Magazine Spring/Summer 2015 Edition.

Indeed, there is a vast rift between scientific evidence for the benefits and risks of GMOs and the public’s perception of the benefits and risks of GMOs. Yet science is the only systematic and replicable tool that humankind has for understanding the world around us. Whether GMOs fit within an individual’s value system or not, they are part of our world, and their impacts on human health and the environment—at least those impacts we choose to investigate—can be understood through rigorous science.

So what exactly does science reveal about GMOs? Well, first let’s talk about what GMOs are.

All organisms change over time—that’s evolution. But some 10,000 years ago, humans figured out they could speed up and direct the process of evolution by selecting individual organisms that exhibited preferable traits and crossing, or selectively breeding, them with each other. Prehistoric humans did this with maize, over time turning the grassy weed, teosinte, which had scrawny clusters of seeds, into a crop that produced plump, nutritious kernels. They also did this with our first pets, dogs, transforming them from their wild wolf ancestors into the incredibly diverse assortment of domesticated canines we know and love today.

To achieve outcomes that once took thousands of years and countless failures, scientists now are turning to genetic engineering techniques, which enable them to speed up the process of evolution and fine-tune it to create precise changes in the physical attributes of organisms to achieve certain benefits.

This type of rapid genetic manipulation began a few decades in the past:

1982, Humulin—a form of human insulin produced by genetically modified bacteria—was approved by the U.S. Food and Drug Administration.

1992, the first GM plant—the Flavr Savr tomato, engineered to remain firm longer to allow for vine ripening—was approved for commercial production in the United States.

1994, Monsanto’s Roundup Ready soybean was given the go-ahead by the U.S. Department of Agriculture.

1997, approval of insect-resistant Bt cotton.

2009, the FDA approved the first GM animal, a goat that produces an anticlotting agent in its milk that can treat people with clotting diseases.

2015, the Arctic Apple, which is genetically engineered to resist browning, was approved by the USDA in February 2015 and by the FDA in March 2015.

Other GM crops approved for sale in the United States today include

  • Potatoes
  • sugar beets
  • rapeseed/canola
  • corn
  • soy
  • cotton

In addition, several varieties of genetically modified crops in the late stage of testing include crops that are salt tolerant, crops that produce omega-3 fatty acids, canola that requires half the amount of nitrogen fertilizer, pink pineapples that contain cancer-fighting lycopene, and wheat with reduced potential to cause allergies. GM animals that are being investigated include salmon growth, chickens resistant to avian influenza, and pigs that utilize phosphorus more efficiently and pollute less.

How are all these organisms created? The simplest method includes using natural enzymes to cut a gene—or fragment of DNA—from one organism and insert it into another organism either indirectly via some kind of vector, such as a virus, or directly via a gene gun or microinjection technique, for example. Generally, the introduced gene confers a new trait to the organism.

Newer techniques for creating GMOs allow scientists to more precisely change the sequence of genes to introduce the desired trait. Known as “genome editing,” the tech- niques involve removing, inserting, or editing a fragment of DNA using bacterial enzymes that are like “molecular scissors.” These enzymes are part of the immune systems of microbes, which use them to edit their own genomes and protect themselves from attack by pathogens.

As it turns out, bacteria and viruses have been doing this “gene swapping” for millennia. Once scientists saw how the microbes did it, it was not long before they developed tools to move genes around in plants and animals themselves. “We now have the ability to edit genes like you would edit a document in your word processor,” said Troy Ott, professor of animal science. “It’s like taking the book War and Peace, turning to page 743, and changing the word ‘man’ to the word ‘woman.’”

To create the most widely used GMOs—Roundup Ready crops, which are engineered to be resistant to glyphosate (the active ingredient in Roundup)—scientists at Monsanto investigated an enzyme in plants called EPSPS. The enzyme is part of a pathway that manufactures three of the 21 amino acids—the building blocks of proteins—that all living things have. Glyphosate binds EPSPS, preventing it from producing these three amino acids.

“The plant gradually starves to death,” said Richard Roush, dean of the College of Agricultural Sciences.

To avoid this outcome for crop plants, the Monsanto scientists found a form of EPSPS in bacteria that is naturally resistant to glyphosate and used it to engineer crop plants that also were resistant. Now, when glyphosate is applied to the crops only the susceptible weeds die.

How GMOs are made—simplified.

In this first-generation example, genes are cut from plants or animals that have a desired trait, and then pasted into plants or animals at precise locations to create a desired beneficial effect.

How GMOs are made—simplified

View complete article here: http://agsci.psu.edu/magazine/articles/2015/spring-summer


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