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Wednesday, August 3, 2016
DNA. The results of a consumer preference survey conducted in January of 2015 by Oklahoma State University's Department of Agricultural Economics indicate that there is sometimes a disconnect between reality and public perception. When surveyed regarding support or opposition to potential government policies, 80.44% of respondents said that they support "Mandatory labels on foods containing DNA". That would be a lot of labeling!
DNA, which is an acronym for deoxyribonucleic acid, is the hereditary material found in all living cells, from the smallest bacterial cell to all of the cells in a fungus, worm, insect, plant, animal or human – from fruits and vegetables, to grains and meats. The information contained in DNA is in a code made up of four different chemical bases. It is the sequence or order of millions these four bases in the larger DNA molecules that makes up an organism's genome. When cells divide to make new cells, the original DNA serves as a template that is used to make new copies of DNA. It is in this way that all new cells will end up with an exact copy of the original cell's DNA, it's genome.
What does DNA do? Genes are sequences of DNA that provide instructions for a cell's machinery to make proteins. The cell's machinery reads the order of the bases in a gene to eventually string together a chain of amino acids. We can think of a cell as a 'a build-a-bike-kit' – the cellular machinery reads the instruction booklet (the DNA) to add parts in a specific order to build a bike (to add amino acids in a specific order to build a protein). The sequence of different amino acids linked together in a string results in certain amino acids being attracted to or repelled by others in the string. The string of amino acids can fold onto itself or bind to other strings of amino acids to form proteins. Proteins perform a lot of different, specific and essential functions in living cells.
Sometimes mistakes are made…… During cell replication, even though there is a proofreading process in place to ensure that an exact copy of DNA from the original cell is made to be placed into the new cell, sometimes mistakes occur. Sometimes the wrong base pair is inserted into the DNA sequence. These naturally occurring mistakes, or mutations, can cause changes in a gene, which can eventually lead to protein changes. Sometimes these changes can be really important. Some mutations are fatal, meaning that an organism is unable to complete its life cycle. In the case of animals (and humans), some mutations can cause birth defects or cancers.
In addition to random mutations, changes to the DNA sequence can occur during a process called genetic recombination. Recombination occurs during sexual reproduction when the DNA in male sperm cells and female egg cells merge into a single cell during sexual reproduction.
We can sometimes see the results of random mutations or genetic recombination in our farm fields. One instance that may be all too familiar - sometimes these genetic changes result in an organism, like a weed or an insect, being better able to survive a pesticide application. Those individuals that have a mutation that makes them better able to survive a pesticide application will reproduce and pass on this genetic resistance to their offspring. This is how pesticide-resistant weed or insect populations develop.
Haven't humans been genetically modifying crops and livestock for ages, and what do these mutations have to do with GMOs? Many thousands of years ago, some of our more observant ancestors domesticated crops and livestock from wild populations. Out of a field filled with many plants of corn's ancient ancestor (called teosinte), humans selected those plants that had some mutation that resulted in a desirable trait, like larger seeds. They saved seed from these individual plants and then the next year likely allowed them to breed with other plants with similar positive characteristics. Over many thousands of years human action has significantly changed many plant and animal species. Our modern-day corn and soybeans look much different from their ancient ancestors, as do our modern-day cattle from their wild oxen ancestors. One could argue that for thousands of years humans have been using naturally occurring mutations and selective breeding to genetically modify crops.
But is this really what people are talking about when they talk about GMOs? GMOs, or genetically modified organisms, are plants or other organisms whose genome has been modified through genetic engineering. Rather than relying on random mutations or traditional breeding, GMOs are made by a complex process that essentially transfers one or more desired genes from one organism into another. Many times genes are transferred to unrelated species: genes from bacteria and viruses have been transferred into plants, genes from one plant species have been transferred into another, genes from humans have been transferred into bacteria. This is how we get the human insulin that is used by diabetics: human genes that code for insulin production were placed into the machinery of bacterial cells. Human insulin can now be made on an industrial scale in large vats of bacteria.
The first genetically engineered row crop approved for sale in the U.S. was soybeans developed by the Monsanto Corporation with the trade name "RoundUp Ready". RoundUp is a herbicide, that was very good at killing plants, including soybeans. RoundUp kills plants by inhibiting an enzyme responsible for the production of three amino acids essential to plant life. In a bacterium called Agrobacterium tumefaciens scientists discovered a modified version of the enzyme that was still able to work in the presence of the herbicide. They inserted this bacterial gene into soybean, which allowed plants to survive a RoundUp application. So RoundUp Ready soybean fields could be sprayed with RoundUp and survive, while other plants did not. This technology was released into the market in 1996.
What GMO crops are out there and what are they? There is a whole list of different crop species that are genetically engineered to perform multiple functions. Here are some examples:
- There are many GMO row crops: cotton, rice, sugarbeet, tobacco, flax, canola, rapeseed, alfalfa, corn and soybeans
- By far the most common type of GMO traits are those that confer herbicide resistance. Herbicide resistant alfalfa, corn, soybean, cotton, canola, sugarbeets and flax are available.
- There are proteins that are produced in a bacterium called Bacillus thuringiensis (Bt). Upon insect ingestion, these Bt proteins cause fatal holes in insect guts. The genes for these Bt traits have been inserted into both corn and cotton so that the plant itself is able to produce the insecticidal protein.
- Some crops like papaya, plum and squash have genetically engineered resistance to specific viral plant pathogens.
- Some crops, including corn, have genes that cause male sterility – so that the corn plant produces ovaries (the female flower parts) but doesn't produce pollen (the male flower parts). In this case the male sterility gene ensures that no self-pollination occurs and the two distinct inbred lines cross to produce hybrid seed.
Are GMOs regulated? Although the regulatory regime is in the process of being updated, beginning in 1986 three federal agencies have been charged with regulating GMOs:
- The Food and Drug Administration (FDA) ensures that food or feed derived from genetically engineered-crops meets the same safety requirements as food derived from conventionally-bred crops.
- The USDA's Animal and Plant Health Inspection Service (APHIS) regulates genetically engineered organisms that may pose a risk to plant or animal health.
- The Environmental Protection Agency regulates pesticides, including plant incorporated pesticides, or those pesticides that are intended to be produced and used in a living plant – Bt for example.
When a company wants to market a crop for sale to the general public, they submit a permit application, which is reviewed and eventually has one of three fates:
- The permit application is never completed or is under review
- The permit application is withdrawn
- The permit application is approved. After approval of the application for a permit, the GMO is considered de-regulated and can be made available for sale.
Most of the time though, there are additional international regulatory hurdles that the GMO must jump in order to be sold overseas. There is often a large lag-time between the time that the new gene is inserted into plant cells and genetically-modified seed is available for purchase.
How many acres in Illinois were planted to GMO corn and soybean? Each year the USDA's Economic Research Service conducts a survey. In 2015 approximately 93% of corn and soybean acres in Illinois were planted to GMO seed - approximately 31,000 square miles or 10.9 million corn and 9.1 million soybean acres.
Each year corn and soybean farmers must decide whether they are going to plant genetically-engineered or conventionally-bred crop seed. These decisions are based on many factors that the farmer needs to weigh:
- Very often there are more GMO than conventionally-bred corn hybrids and soybean varieties for producers to choose among
- Costs for genetically engineered seed tend to be significantly higher than for conventionally-bred seed
- There may be additional management considerations when planting a GMO crop
- In the case of some of the Bt crops there might be a legal requirement to plant a portion of the crop to non-Bt seed
- In the case of non-GMO soybean, there might be fewer in-season herbicide options
- In some regions, depending upon the markets for individual grain elevators, there may be a premium for producing non-GMO grain.
Are GMOs safe? A comprehensive study of this topic was recently completed. Within the last couple of months, the National Academies of Sciences released a 420 page report titled: Genetically Engineered Crops: Experiences and Prospects.
Reports by the National Academies carry a lot of weight because the academy members are some of the world's most distinguished scientists, engineers, physicians, and researchers; more than300 academy members are Nobel prize-winners. The academies were founded by congressional charter in 1863. At that time President Lincoln had the foresight to understand that the federal government had an urgent need for independent advice on scientific matters, and urged that the academies be founded to serve this purpose.
The report had several conclusions:
- All available evidence indicates that genetically engineered corn, soybean and cotton have generally had favorable economic outcomes for those that produce them. However, the outcomes for individual farmers have varied depending on factors like how many insect pests there are in the field and other farming practices.
- The academy found that crops with the Bt insect-resistant traits generally decreased both yield losses and the use of insecticides when compared to conventional crops. In some cases, the widespread adoption of Bt crops decreased the abundance of insect pests even in crops that didn't carry the Bt trait. Widespread use of Bt crops also resulted in higher insect biodiversity in farm fields than in conventional crops that are sprayed with insecticides.
- The academy's report also talked about the effect of poor trait stewardship and the relatively fast evolution of herbicide-resistant weeds and insecticidal-trait-resistant insects.
Perhaps most important to the non-farming public, the claims that genetically engineered crops have had adverse effects on animal and human health were investigated. The academy found no evidence that foods from genetically engineered crops were less safe than foods from conventionally-bred crops. Regardless, President Obama recently signed legislation that will create a nation-wide labeling system that prevents a patch-work of state-by-state labeling laws while allowing consumers to more easily understand whether the food that they are purchasing contains genetically modified ingredients.
The academy report did conclude however that the value of genetically engineered crops depended upon three things: the fit of the trait and plant variety on a farm, the quality of the seeds and their cost. The academy also acknowledged that the problems associated with crop production and feeding the world are complex and can't rely on GMOs alone.
More recently, there has been the discovery and development of gene editing technology. The potential possibilities and pitfalls of this newer CRISPR/Cas 9 technology is just being explored. This is likely one reason why the regulatory process is being updated – to ensure both human and animal safety and the safety of all of the living organisms in nature.