DNA Model and Vegetables in Refrigerator © Günay Mutlu via iStockphoto.com
Back in the days when I had grand plans for this blog, before a slew of family issues, health problems (and all the attendant depression that goes with all your grand plans getting totally messed up and not wanting to get bogged down with any negativity in my writing), I promised my readers a series on GMOs. After my poor friend Thelma Lee spent many hours working on an article that would give readers a scientific understanding of GMOs, I just tanked with the blogging for a time. Sourcing photos and deciding what I might be able to say or not say (legally) in any follow-up posts (after receiving some cautionary advice from a reader and a friend) made it all seem daunting. But, given the ever evolving world around us, the topic seems more relevant than ever. In the wake of violent storms, floods, droughts, earthquakes, volcanic ash thick enough to scramble international flight patterns and therefore affect sunlight in some agricultural areas, the issue of genetically modified agricultural products is timely.
Actually, though you might think most about GMO foods, GMOs impact three areas of our world currently- agricultural (yes, food products, but what about textiles fibers, and other applications?), medicinal (think vaccines or drug delivery or vitamin augmentation) and industrial (think waste remediation, for example). But what do you think when you hear about GMOs? Many people think:
But what is it that you're actually saying no to? And... should you be?
Most people have no idea what the deal is with GMOs. I feel strongly about such subjects because as a PhD chemist, I'm weary of hearing that 'chemicals are bad'. Your body is made up of a delicate balance of chemicals. 'Chemicals' are not bad. And let me tell you, not all organic stuff is good, either. Wanna talk about some natural or organic stuff that's bad? I could go on for days, listing things like arsenic (naturally occurring), radon (naturally occurring), ricin (naturally occurring), saxitoxin (naturally occurring) or how about a humble little protein called avidin, found in egg white and which binds the vitamin biotin with one of the highest affinities known, to name but a few. Avidin is actually one of the reasons that you shouldn't eat raw egg whites. (Biotin is kind of useful in the human body, ya know?) But avidin, which on the face of it might seem bad, has actually been an incredibly useful tool in biological and medical research science.
The goal of Thelma Lee's article (split into two parts, so you can better absorb the information) is to explain the current science behind GMOs and some of the lofty goals that GMO producers have explored, many of which have been, or are on the verge of being, achieved. And you should ask yourself, as you read, if GMOs really sound all that bad, once you understand them better? And if you're still unconvinced, ask yourself: Is every GMO bad? Is the science bad? Is the business angle or potential for monopolies of a GMO product bad? Does the potential for good far outweigh the potential bad? The facts may challenge your thinking and, at a minimum, will have you considering:
Genetically Modified Organisms: Is it Nice to Fool Mother Nature?
by Thelma Lee Gross, DVM
Introduction and Background
Since the 1953 discovery of the chemical structure of DNA by Watson and Crick, humans have wanted to manipulate it. A unique double helix of chains of sugars and phosphates attached to nitrogen bases (adenine: A; cytosine: C; guanine: G; and thymine: T), DNA both codes for the production of proteins and controls which ones are turned on or off; i.e., made or suppressed. In this way, the characteristics of an organism are genetically determined for traits such as disease resistance or products such as hormones. Modifying DNA meant that humans might change the outcome of a cellular characteristic or product in a more specific and controlled fashion than by the conventional routes of selective breeding and, later, mutagenesis, which is the relatively nonspecific alteration of genetic material using chemicals or radiation.
Using enzymatic scissors (endonucleases, exonucleases) and glue (ligases), scientists soon learned how to manipulate DNA and its subcomponents, genes. In 1973, Stanley Cohen and Herbert Boyer invented the technique of DNA cloning, which created copies of the segment of DNA under study. By increasing the amount of DNA available for manipulation, this technique allowed genes to be transplanted between different biological species and signaled the birth of genetic engineering.
In order to produce a genetically modified organism, or GMO, the gene or genes must be chosen, replicated and isolated, and then transferred to the host genome. Plasmids, circular pieces of DNA usually found in viruses or bacteria, are common vectors or vessels of transfer, particularly for plants. Simply put, the spliced gene is incorporated into the plasmid by cutting its circular structure, inserting the new genetic material, and closing the circle. The plasmid is then inserted into the host via plasmid-infected bacteria. Genes can also be “shot” via microinjection into host cells in cases where plasmids cannot function well in this capacity, particularly in the case of animal cells. The organism is then regenerated from the transformed cells. Antibiotic exposure to eliminate non-transformed organisms that do not co-express an antibiotic resistance gene, polymerase chain reaction (PCR), or bioassay testing is required to insure that the chosen gene is expressed in the regenerated organism and will function as expected.
Next I will outline the current use of genetically modified plants and their benefits to agriculture, medicine, and industry.
The Use of Genetically Modified Organisms in Agriculture
Genetic modification of food crops has been directed to several key goals. Crops have been altered to resist pests and herbicides; to improve nutrition; to survive in climactically or soil-challenged locations; and to provide increased yield, improved taste, and longer shelf survival.
Pesticide Resistance The principal types of genetically modified crops that resist pests are those containing the Bt (Bacillus thuringiensis) gene, which produces a bacterial-derived larvicidal toxin. Bacillus thuringiensis toxin displays no significant effects on the environment, or mammals and birds, but is toxic for certain species of caterpillar larvae. Crops that are modified to be pest-resistant can be beneficial in several ways. The use of Bt crops reduces the use and therefore the cost of chemical pesticides. Bt cotton has been highly effective in reducing the need for Bt pesticide in commercial production.
Secondly, GMOs containing pesticide have been found to protect conventional crops in the vicinity, as in recent studies of Bt corn planted alongside conventional corn. Conventional corn was protected from borers simply by co-planting with Bt corn. This increased yield and reduced overall cost since conventional corn is less expensive to grow.
Lastly, naturally occurring, pest-protective genes from one crop plant can be inserted into another, thus “sharing the wealth,” as in the recent studies of natural proteinase inhibitors of potatoes and tobacco that were transferred to cotton. Transferring inhibitors from more than one source increased the resistance of cotton to caterpillar pests because caterpillars quickly develop new proteinases when exposed to one type of inhibitor only. This stacking technique improved the performance of these GMOs.
By all available evidence, Bt crops are beneficial to farmers. The supposed failure of Bt cotton in India may be linked to the use of spurious seeds and the planting of cotton in inadequate and under-irrigated soils, which produces failure of all varieties, Bt cotton included. Farmers who can show crop failure may be able to obtain cash settlements, thus increasing the incidence of claims.
Herbicide-resistance This group of GMOs is best known by the “Roundup (glyphosate) Ready” group that include soybeans, corn, canola, cotton, and, more recently, sugarbeets and wheat. These crops are modified to resist the use of the herbicide. The planting of these modified crops allows farmers to use less tillage (another method of weed control that physically removes the weeds), thus reducing soil erosion and assisting in soil conservation. Studies have also found water contamination of more harmful pre-emergent herbicides is reduced in areas of Roundup Ready crop plantings. Farmers’ production costs are lowered; thus, there has been rapid and widespread adoption of this type of GMO.
Disease-resistance This area of research in genetic modification is more problematic, and results have been slow. There has been limited success in genetically modifying organisms that resist bacterial diseases, for example. Efforts to fight “greening” of Florida oranges, a disease caused by a bacterium that is spread by a tiny insect (psyllid), have been heretofore of limited success. As the January 10, 2011 article in the New Yorker explains (“We have no bananas”), the drive to save the commercial banana, the Cavendish, from the fungal disease Tropical Race Four is being aided by one group of researchers which successfully inserted a gene from thale cress that resists a related disease, Race One, into another strain of banana. Early results are promising, but large scale production of resistant strains is still likely years away and it may not outpace the ultimate destruction of the crop worldwide.
Nutritional Augmentation Genetically modified microorganisms are already increasingly used to manufacture vitamins, enzymes, flavors, and other food additives. Improving the nutritional content of food crops, or biofortification, also may be accomplished by genetic modification. Most of these food crops are not yet available for use. An important recent example is “Golden Rice,” which should be ready for release within the year. Syngenta donated several of its patented technologies to the Golden Rice project for humanitarian purposes, with other biotech companies also making contributions. Golden Rice is the product of modification of two genes, which enables production of up to 35 micrograms of beta carotene (a precursor of vitamin A) per gram of edible rice. Rice can make beta-carotene in its leaves, but the modification gives the same ability to the rice grain. This food is expected to avert blindness and death throughout areas of the third world where rice is the staple.
via Wikipedia, under Fair Use
The legal hurdles are phenomenal, however. Golden Rice was ready in 1999 and was featured on the cover of Time Magazine (shown above) in 2000 with its co-inventor, Ingo Potrykus. It is still going through the regulatory process. As stated by the Golden Rice Humanitarian Board: “It will take at least until 2011 before the first Golden Rice obtains final regulatory approval and can reach the first group of small holders in a target country. Considering the enormous humanitarian potential of Golden Rice in reducing blindness (500,000 children per year) and children's deaths (2-3 million per year), it is hardly understandable that lobby groups and the authorities are not learning from the accumulated experience and making the regulatory process more science and experience based.” Professor Potrykus, a member of that board, addressed the humanitarian issues of such a delay in his opinion piece in the July 2010 issue of Nature.
In 2009, researchers in Spain, writing in Proceedings of the National Academy of Sciences (PNAS), reported they had genetically altered corn to contain 169 times the beta carotene of normal corn, 6-fold the normal amount of vitamin C, and twice the normal amount of folate. The beta carotene concentration is reportedly five times higher than in Golden Rice.
In 2009, researchers in Spain, writing in Proceedings of the National Academy of Sciences (PNAS), reported they had genetically altered corn to contain 169 times the beta carotene of normal corn, 6-fold the normal amount of vitamin C, and twice the normal amount of folate. The beta carotene concentration is reportedly five times higher than in Golden Rice.
Transgenic potatoes in India have 60 per cent more protein per gram than conventional potatoes; a medium potato can provide 10% of the daily protein requirement of an adult. As a surprise bonus, the GM crop also yielded more potatoes per unit area planted. Flavonoid-enhanced tomatoes, increased carotenoids in potato tubers, and increased essential fatty acids in soybeans and canola have also been developed. This area of GM research is developing exponentially so more products should emerge rapidly in the next few years.
Survival in Challenging Soils and Climate The International Rice Research Institute runs its own GM programs. Traits like efficient water and nitrogen use and tolerance to salinity and flooding are early targets. In September of 2010 an Australian group produced a salt-tolerant form of rice, which traps salt in the root of the plant, preventing its transfer and damage to the more susceptible shoots.
Water Efficient Maize for Africa (WEMA) varieties are being tested and should result in increased yields by up to one third. This allows farmers to grow maize successfully in dry areas that may have been below subsistence levels. This area of GMO development will continue to provide crops that can be grown in areas of greatest need where soils and climate are perennial challenges.
Improvement of Quality and Yield A laudable goal for genetic modification is the improvement of yield as well as quality of the food product. Yield and flavor-enhanced varieties of GMOs provide a one-two punch and appeal to growers and consumers alike. Dr. Zachary Lippman of Cold Spring Harbor Laboratory has modified a single copy of a mutant gene in tomatoes, which has resulted in increased production per plant and simultaneous sweetening of the fruit. These potent producers are the result of manipulation of the “flower power gene,” known as SFT, which tells the plants how many flowers to make. This scientific manipulation may lend itself to all kinds of crops, including melons and soybeans.
The Use of Genetically Modified Organisms in Medicine
In human medicine genetic modification of organisms first allowed the manufacture of products which until then could be obtained only in small quantities from a natural source. In 1982 insulin produced by a genetically altered bacterium was approved for use in humans. Human growth hormone, factor VIII (for clotting disorders), and interleukin-2 (to fight cancer) are other important examples. Artemisinin, the world’s most important anti-malarial medicine, which previously could only be naturally sourced from sweet wormwood (Artemesia annua), now can be efficiently synthesized in bacteria, reducing its cost by 90%. It will be commercially available to victims of malaria by 2012, as reported in the September 28, 2009 issue of The New Yorker in an article about synthetic biology (“A Life of its Own”).
GM plants also have increasing importance in modern medical application. Tobacco is being used to produce flu vaccine. Indeed, according to the January 31, 2011 issue of the New Yorker Magazine (“Going Viral”), during the recent fear over a swine flu pandemic, scientists affiliated with the U.S. government adapted the tobacco technique to swine flu vaccine, rapidly accelerating production to about a month from the approximately six months required by the traditional technique using hen’s eggs. Rice is being modified to provide oral cholera vaccine, to orally treat cedar allergy, and to contain reduced protein levels so that it may serve as a nutritional source for renal failure patients who cannot tolerate much protein in their diets. Several varieties of rice have also been modified to fight iron deficiency anemia by expressing lactoferrin; this rice is also superior nutritionally, having higher available protein for absorption.
The Use of Genetically Modified Organisms in Industry
Plants, including those that are traditionally used for food, are being genetically modified for industrial application. Potatoes are being engineered to make only one of its usual component starches, amylopectin, which can be utilized in the production of paper and concrete. Called the Amflora potato, its use was approved for the European Union market in March 2010 by the European Commission. Maize plants are being engineered to produce enzymes such as Trypzean, a transgenic trypsin that is used in industry.
Tobacco may be used in future to remove organic pollutants from the soil in a process called “phytoremediation”.
Next I will deal with various problems that have arisen through the use genetically modified plants.
Part 2 of Thelma Lee's article will be posted tomorrow.
In the meantime, your homework? Here is some rice. Imagine it has been genetically engineered to have a cholera vaccine in it. Good thing? It sure sounds like it whether you live in India or Burma or Haiti. Who owns it? Who paid for the research studies of it? Will they give it away in regions prone to cholera outbreaks? Can the genes be transferred to rice plants that weren't genetically engineered? Should we even worry if they could? These are some of the many and varied issues surrounding GMOs.
To see a cure in a grain of rice...
Rice © Srdjan Stefanovic via iStockPhoto.com
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