1

Discussion about GMOs (genetically modified organisms) in our food supply is everywhere in the news. Some people support the idea that GMOs can provide better quality food to more people worldwide. Other people fear that GMOs will seriously damage human health and the environment.

So what are GMOs? GMOs are plants, animals, and microbes whose DNA has been changed through genetic engineering techniques. Scientists insert genes from one organism into another or turn off existing genes. Mice are genetically engineered to be models for biomedical studies. Bacteria are engineered to produce medications such as insulin or enzymes used in cheese production.

Some genetically modified plants are used as crops to feed humans and animals. GMO crops, especially corn and soybeans, are widely grown in the United States. GMOs for food use in other countries varies. So far, one genetically altered animal, the AquAdvantage salmon, has been approved by the US Food and Drug Administration as human food.

Should we go with GMOs?

GloFish® are genetically modified fish. The original idea was to create

fish that could detect pollution by fluorescing (glowing) in the

presence of certain toxicants. The fish sold as pets don’t do this. They

simply glow using the same gene as found in jellyfish.

I am the only genetically modified animal

currently sold as a pet.

What are GMO foods good for?Scientists develop genetically engineered crops to improve the organisms we depend on for food by making them grow faster, thrive under different climate conditions, resist herbicides and insect pests, have better flavor, or be more nutritious. Here are some examples of foods currently sold in the United States. Other products are in development in the US and wordwide.

Bt corn and soybeans are resistant to certain insects without the need for pesticides. Bt corn and soybeans were engineered by inserting genes from Bacillus thuringiensis (Bt), a bacterium that occurs naturally in soil and produces proteins that kill specific insects.

AquAdvantage salmon grow at about twice the normal rate. So, they can be sold for food more quickly. AquAdvantage salmon were engineered by changing a gene that controls a growth hormone.

Roundup Ready soybeans and corn allow farmers to apply the herbicide glyphosate (brand name Roundup) to kill weeds without harming the soybean or corn plants. Roundup Ready crops were engineered by inserting a gene that makes an enzyme that’s not affected by glyphosate. The gene for this enzyme was

found in a soil bacterium called Agrobacterium tumefaciens.

Ringspot virus resistant papyas grow even where the virus is present in soil. Hawaiian farmers started growing these papayas in 1998. Virus resistant papayas were engineered by inserting genes that make virus proteins. These genes trigger a plant response against the virus and stops its effects.

Arctic Apples do not get brown after they are cut open like other apples do. Arctic apples are engineered by inserting a DNA sequence to turn off the genes that produce an enzyme called polyphenol oxidase (PPO). PPO is required for browning.

Scientists have been creating GMOs since the 1980’s.

2Should we go with GMOs?

How are GMOs made?Whether genetic engineering is used for biomedical studies, producing medicines, or food, GMOs are created using the same basic steps: identify a trait of interest, isolate the genes for the trait, insert that trait into desired organism, and grow the engineered organism. The technology is always advancing, but the methods shown here are commonly used.

GMO graphic adapted from Science in the News, Harvard University.

Agrobacterium tumefaciens

bacteria naturally invade

plant cells and insert their

own DNA. This behavior is

exploited as a tool for genetic

engineering.

Yes, you are eating GMOsIf you live in the USA, and if

you do not exclusively eat organic foods (which don’t

contain GMOs), you are eating genetically modified foods

in some form.

As of 2014, the USDA reports the percent of

GMO crops grown in the USA as:

Soybeans – 94% GMOCorn – 93% GMO

Cotton – 96% GMOSugar Beets – 90% GMO

When genes inserted into a plant come from a different kind

of plant or another organism, the resulting GMO is called

“transgenic.” Sometimes, like in the Arctic Apple, the inserted gene comes from the same kind

of plant. This type of GMO is not transgenic.

3Should we go with GMOs?

We’ve seen that GMOs are defined as organisms whose DNA has been altered with genetic engineering techniques. This technology has only been around for a few decades.

But humans have been altering the DNA of organisms for many thousands of years. Let’s find out how that’s possible!

Do you have a dog as a pet? Even if your dog is a breed like a Husky that looks similar to a wolf, you can easily tell that dogs and wolves are quite different. Your dog loves to play and cuddle with you. Wolves are secretive animals who don’t like being close to humans. Genetic studies show that wolves are the ancestors of dogs. So how did wolves and dogs become so different?

The answer is something called selective breeding. As many as 30,000 years ago, wolves that were more tolerant of humans began hanging around, perhaps following human groups for food scraps. These friendlier wolves were selected by humans to breed together, producing even friendlier pups. Many, many generations later, humans had the animals we now know as dogs to be companions and do jobs such as protecting us and helping us hunt.

Calling dogs a sort of “GMO” (genetically modified organism) wouldn’t really be wrong. People didn’t modify wolves’ genes in a laboratory, but their genes were changed by our actions. Dog genes and wolf genes are no longer the same.

• People picked animals with desireable traits and bred them together. Desireable genes that started out being rare in the wolf population became more and more common in dogs.

• Through mutations, dogs gained new genes that never appeared in wolves. If a mutation produced a desirable trait, people bred dogs with that trait to each other, and the new gene became established in dogs.

• Fast forward to today, and we have everything from 5-pound Chihuahuas to 150-pound Mastifs.

Selective breeding has produced a rainbow of carrots.

The ancestor of modern corn, teosinte, is on the left. Selective breeding has resulted in modern corn. (Photo courtesy of John Doebley.)

And on to corn… In the same way, people have changed the genes of plants for their benefit. For example, we enjoy biting into a plump, juicy ear of corn. But the ancestor of corn, teosinte, has a tiny stalk of kernels, each sealed inside a hard shell. About 10,000 years ago, ancient farmers (in what is now Mexico) noticed that some plants had bigger cobs and softer kernels. By breeding those desireable plants together, more of the resulting crop would have those traits, and maybe even better ones. Many, many generations of breeding have resulted in the corn we know today.

grey wolf

Good nutrition to battleenvironmental toxicants.

Developed by

through funding from

Grant number R25 OD011090

Selective breeding is a low-tech way to modify genes

“GMOs” before Genetic Engineering

4Should we go with GMOs?

What worries people about GMOs?Untangling the web of news stories about GMOs is not easy! Google “GMO” you will see everthing from “10 Reasons to Avoid GMOs” to “GMOs May Feed the World Using Fewer Pesticides.” Before going “pro” or “con,” consider the source of the article and the background of the author. Also, dig deeper! In science, a single research study is rarely a complete answer. Based on hundreds of scientific studies, the American Medical Association (AMA), takes the position that bioengineered (GMO) crops and foods offer many potential benefits and encourages ongoing research developments in food biotechnology. However, the AMA also supports mandatory safety assessments of bioengineered foods and development of more ways to detect unintended harmful effects. A National Academy of Sciences report on GMO safety points out that traditional breeding methods can also have unintended effects, such as a case where scientists bred the cultivated potato with a wild potato. The hybrid (a product of two kinds of parents) produced a toxic chemical called demissidine, even though neither parent had contained it.

March Against Monsanto is a social

movement to protest Monsanto Corporation’s

production of GMO crops. Group members want

labeling to be required for food containing GMOs.

Will antibiotic-resistant genes in GMOs create antibiotic-resistant bacteria in our bodies?

Antibiotic-resistant genes are used to make some GMOs. These genes are already common in bacteria naturally

found in soil and in human bodies, and they don’t seem to cause a problem. However, antibiotic resistance overall is

a health concern, and some GMO producers are replacing antibiotic-resistant genes with other types of genes.

As we’ve seen, each GMO is engineered to do a specific job. So, people’s questions and concerns vary depending on the GMO. Some examples follow.

Do herbicide-resistant GMOs

promote development of herbicide-resistant weeds? Herbicides can be used on

herbicide-resistant GMOs to kill surrounding weeds without harming

the crops. Weeds rapidly evolve to resist the herbicide and can invade farmlands.

Also, in very limited cases, herbicide-resistant GMOs can crossbreed with close relatives and pass on

the resistance gene. If these crossbred plants become

invasive, it could be a problem.

According to the Pew Research Center, 57% of Americans think GMOs are unsafe to eat. 88% of scientists say GMOs are safe.

Don’t Forget Diversity!Whether food is developed by selective breeding or genetic engineering, genetic diversity is the “library” of source material we have to work with!

If everyone plants the same kinds of crops, genetic traits in less popular varieties can be lost forever. The thousands of undiscovered genes in less popular varieties may have the potential to help produce better growing, better tasting, and more nutritious food.

Aside from producing tasty food, growers of heirloom fruits and vegetables (varieties introduced 50+ years ago) are helping to preserve genetic diversity that would otherwise be lost.

HEIRLOOM TOMATOES COME IN MANY SHAPES AND COLORS!

Will RNA used to turn off genes in GMOs like arctic apples turn off

our genes? Small RNA molecules (called miRNA) exist in all plants and animals and can turn genes on or off. New miRNA

is inserted in some GMO crops to change how genes are expressed. Some people worry that we will absorb this inserted miRNA when we eat the food, and the miRNA will turn off some of our genes. However, the action of miRNA

is very specific, so miRNA that targets genes in plants is not likely to affect humans. Also, many studies show that DNA and RNA from

foods are broken up in digestion and don’t get absorbed in a working form.