A crash course on GMOs

Picture this: you take a bite of boiled corn on the cob, then find out that it has been genetically modified with Bt, a toxin that kills corn borers. Will you die just like these insects? Should you write your last will and testament?

This Bt corn is an example of a GMO – a genetically modified organism – so-called because a gene from an outside source, the soil microorganism Bacillus thuringiensis, has been deliberately added to the plant. This added gene makes a substance that is poisonous to a particular type of insects that includes corn borers. Man does this because he is sick and tired of these corn borers that extensively destroy his crops.

For thousands of years, man has been randomly mixing genes by crossbreeding two plants or two animals, hoping to get desirable traits in the offspring. This method is nonspecific and unpredictable; the offspring in fact may carry both desirable and undesirable traits of the parents.

Thanks to the discovery in the 1970s of tools needed for genetic engineering, we can now choose and transfer the gene we want into the genetic material of the recipient organism, which then becomes a GMO or a transgenic organism. The transfer is specific, and the desired trait is predicted.

In medicine, drugs may be produced in bulk by microorganisms. Take for example, insulin, a protein needed by diabetics to lower their blood sugar. Before the advent of GMOs, insulin was extracted from thousands of pancreata (plural of pancreas) of pigs and cows. Human insulin was isolated from the pancreata of cadavers. Now, we don’t have to rely on these pancreata that are better put to use for organ transplants because the gene for human insulin has been introduced into bacteria.

And since these microbes multiply very fast, these millions of bacteria produce lots of human insulin. Whereas one pancreas would yield only a few milligrams of insulin, a few liters of the bacterial culture would produce much more. Vaccines, hormones and other therapeutics are now produced by microbes and other organisms. We have ongoing researches at the National Institute of Molecular Biology and Biotechnology (NIMBB) at the University of the Philippines in Diliman where we produce vaccines and therapeutic antibodies from GMOs.

In "gene pharming," pharmaceuticals are produced from transgenic farm animals. ("Transgenic" means that the organism possesses genes from different species.) Therapeutic proteins like human blood clotting factors may now be found in transgenic milk. Hemophiliacs eventually will no longer have to rely on blood transfusions where diseases like AIDS may be contracted.

The benefits to food and agriculture are vast. Given the rates of Vitamin A deficiency and rice consumption of Filipinos, it is practical that Vitamin A rice, which is developed by IRRI, be made available. In UP Los Baños, papayas with a delayed ripening trait are grown for better storage and transport. This institute is also researching on transgenic coconut with improved components.

The environment likewise benefits from GMOs. Pest-resistant crops mean reduced use of chemical insecticides that damage the biodiversity within the locality. It also means reduced accumulation of cancer-causing chemicals in the ecosystem. Herbicide-tolerant plants mean environment-friendly herbicides may be used to destroy weeds so that farmers do not have to till the soil, thus preventing soil erosion. There are also genetically modified bacteria that can clean up pollutants like oil spills.

So far, the only approved GM crop for commercial propagation is Bt corn, after six years of research and field trial testing in the country. However, there continues to be a raging controversy about the planting of Bt corn. The latest involves villagers residing near the Bt corn fields who were stricken ill. Bt corn pollen was allegedly the cause. However, there is no scientific evidence to substantiate this claim to date.

We are assured of the safety of GM foods by our government agencies. The Bureau of Plant Industry of the Department of Agriculture has stringent requirements for the importation of GM plant and plant products.

But in dealing with the GMO debate, it is human logic that will resolve issues on human technology. This Bt substance, a protein, exists in an inactivated form; it is activated only in the alkaline medium of the insect’s gut. Once activated, the toxin binds to specific receptors in the insect’s gut and bores holes through the membrane. The toxin is thus known as gut poison. But our stomachs are acidic; thus, the toxin cannot be activated. Furthermore, we do not have receptors to bind to the toxin. So what happens to the Bt substance in the corn that we eat? This will be treated by our digestive systems just like any protein, and will be broken down into tiny pieces. Eating Bt corn is no different from non-Bt corn.

Is there any perceived risk for GMOs? Like anything novel, of course, there is. There are concerns especially regarding the long-term effects such as "superbugs," or insects that have evolved to be resistant to insecticides. Constant vigilance and proper awareness of this issue are the best weapons against these. The bottom line is, do the benefits from GMOs outweigh the risks? Unless we want to continue living with the problems of food shortage, crop destruction, medical deficit and environmental decay, the answer is yes.

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Ameurfina Dumlao-Santos, Ph.D. in Molecular Biology and Biotechnology, is a professor at the National Institute of Molecular Biology and Biotechnology, College of Science, UP Diliman. Her research projects include the generation and characterization of recombinant antitumor antibodies and antibody fragments, and the molecular biology of the venomous mollusks Conus and Turrid. Send queries or comments on this article to [email protected].