The original version of this article was published in the Kelowna Daily Courier in November, 2013.
One of the first topics covered in first year biology is the mechanism by which cells decode DNA and make protein. It takes some effort for students to master these concepts and I don’t expect non-biologists to fully understand them, but I am still surprised by the level of misunderstanding evident in the debate over genetically modified organisms (GMOs). The anti-GMO activists interviewed at a recent rally in Kelowna had many of their facts quite jumbled. For example, one person seemed to think that “non-GMO” meant “organic”. So, while my students prepare for an exam I thought I would offer a primer on DNA and GMOs that might make the subject a little clearer. There won’t be a test.
The food safety debate surrounding GMOs mostly centers on the fear that food made from a modified plant or animal will contain something harmful as a direct result of the modification. This understandable concern was, of course, shared by scientists who have now accumulated a very large body of research on the effects of eating GMO food. In the end, after thousands and thousands of studies, no harm has been found. GMO critics, however, don’t trust the testing agencies and they worry that there may be long-term effects that we don’t yet know about.
Before we delve into all this we need to know what a GMO actually is. The term “modification”, in the most relevant usage, refers to the alteration of an organism’s DNA in some way by artificial means. Natural selection has been altering DNA for billions of years and breeders do it all the time, albeit slowly, but this debate is about manipulation using modern genetic methods in a lab. DNA is found in the nucleus of cells in the form of long strings of millions of subunits. There are four kinds of subunit and their sequential order is the genetic code that the cell’s machinery reads when it makes a protein. Different sections of the code provide instructions for making different proteins and the cell decides which ones to read at any given time. These sections of DNA are called genes. Humans have 23 different versions of these long strings, called chromosomes, each with different genes on them. In total our chromosomes carry about 20,000 different genes and, since we have two copies of each chromosome, we may have 2 versions of some genes. Together, all the genes on all the chromosomes of an organism are collectively called its genome. We modify genomes by moving or altering genes. When a GMO gets a gene from the genome of another species we call it a “transgenic” organism. The modified organism can now make the protein coded for by the new gene.
Although all of this sounds technically difficult, it is actually fairly trivial. Our molecular biology students have been inserting green fluorescent protein genes into bacteria for years, causing them to glow a lovely green under UV light. GM bacteria and yeasts are routinely used to produce a variety of products that are otherwise expensive to extract or synthesize. Most insulin used by type I diabetics and all hepatitis B vaccines today are produced in this manner.
When genes are inserted into food-producing plants some anti-GMO activists worry that the transgenic DNA may be harmful when ingested. I heard one critic say “I don’t want to eat food with DNA in it”. In fact every organism, from bacteria to elephants, contains DNA and you eat it all the time. Unmodified DNA and GMO DNA are both broken down exactly the same way in your gut. Chromosomes are genetically active only when they are inside your cells’ nuclei – DNA fragments in your gut are just food.
Other concerns are the “new” proteins GMOs can produce. For example, a peanut protein theoretically could be produced in fish and people with peanut allergies might be harmed if they ate the GM fish unknowingly. Perhaps some new, harmful protein combination might occur. For these reasons, scientists plan carefully which genes they move around and their products are tested much more rigorously than any other processed food on the market. We trust all the other food producers to refrain from adding toxins to food so why don’t we trust GMO farmers? We also encourage them to produce food that is cheaper and more nutritious but we hobble their ability to do so when we eschew GMOs.
Everybody loves to hate Monsanto but the Golden Rice they helped distribute was a wonderful gift to the world. Originally produced by a group of Swiss scientists as a humanitarian project, the modified rice was given a daffodil gene that produced vitamin A. The current version uses a maize gene. Vitamin A deficiency causes blindness and death in children all over the world making Golden Rice a triumph that subsistence farmers can grow it for free. The developers ensured that these Golden Rice licenses would be free in perpetuity and Monsanto was one of the first companies to distribute it. For free. However, that gesture didn’t prevent the subsequent vilification of Monsanto over Roundup Ready plants.
Roundup Ready crops are thought to encourage more use of Roundup but, in fact, less pesticide is normally used. There are certainly big problems with monoculture crops and our food supply is in trouble, but it’s not the fault of GM crops. We had monocultures and environmental degradation long before they came along. In fact GM crops have helped to stem the tide in many ways by providing more food and using less pesticide to do it. Early on there were some worries that GM crops were negatively affecting some insect populations but that turned out not to be the case.
Currently most processed foods in North America made from corn and soybeans use GM crops and we have all been eating them for a long time. If they are banned there will be a shortage of many products. Personally I am rooting for the return of the tasty tomato. Perhaps scientists can create a GM tomato that is commercially useful yet as tasty as a heritage variety. That’s something I would pay extra for.
Update for 2015: The Golden Rice Project won the 2015 Patents for Humanity Award.
Controversies about GMOs: http://en.wikipedia.org/wiki/Genetically_modified_food_controversies