A Genetically Modified Organism (GMO) is an organism(plant, animal, microbe) whose DNA has been altered using Bioengineering Techniques. It includes Recombinant DNA Technology and Reproductive Cloning. The first animal cloned using this technique was a sheep named Dolly, in 1996. Crops like corn, cotton, potatoes were also engineered using this technique which led to an increase in per area crop yield and reduction in the use of a chemical insecticide. For Ex: Bt-cotton when compared with non-Bt-cotton gave a 30-80% increase in crop yield. Herbicide Resistant Crops(HRCs) have been available since the mid-1980s, which are resistant to weeds. GMOs have ameliorated Biomedical assays by enabling the generation of cheaper and safer vaccines and therapeutics. For Ex: Hepatitis-B produced by GM Baker’s Yeast. Another application of GMOs is in the management of Environmental issues (plastic pollution), which can be prevented by using Biodegradable Plastics. Though there are many advantages of using Bioengineering techniques, it has some disadvantages too like to cure human diseases. Many animals(monkeys, rats, etc…) are being harmed, which may affect their species extinction. So, alternative techniques must be considered, as these techniques can resolve medical and environmental issues if used wisely.
In genetic modification, GMO is a technique, using recombinant DNA technologies, to produce organisms whose genomes have been precisely altered at a molecular level, usually by the inclusion of genes from unrelated species of organisms, that code for traits that would not be easily obtained through conventional selective breeding. These organisms can be produced using scientific methods that include reproductive cloning and recombinant DNA technology. In reproductive cloning, the nucleus is extracted from a cell that has to be cloned and is introduced into an en-nucleated(without nucleus) cytoplasm of the host cell. This process concludes with the generation of an offspring that is genetically similar to the parent individual. Using these techniques “Dolly the Sheep” was produced in 1996 and since then, many different animals like pigs, horses, and dogs have been produced. And on the other hand, recombinant DNA technology involves the insertion of one or more individual genes from an organism of one species to the DNA of another. GMOs have been introduced in fields like agriculture, medicine, and research. And how are they being used, are as follows:
Figure 1: "Dolly" the sheep
1. GMOs in agriculture:
In the United States, in the 1990s Genetically modified (GM) foods were first permitted, and by the end of 2014, almost 1.8 million square kilometers of land were blanketed by (GM) crops. For example, in America crop yields were deteriorating, so they endowed a gene from Bacillus Thuringiensis into crops like potatoes, corn, and cotton which produced a natural insecticide called Bt toxin. Field studies in India demonstrated a 30-80% increase in crop yields. In America and China, crop yield increased up to 5%, owing to a 50-80% reduction of pesticide applications. Bt resistance has also evolved in the field population of major cotton pests including cotton bollworm(Helicoverpa armigera) and pink bollworm(Pectinophora gossypiella). Other GM plants are engineered to resist the chemical herbicide, so the name Herbicide-Resistant Crops (HRC). These are extremely effective against weeds, which prevents soil erosion.
Figure 2: Genetically Engineered Corn Figure 3: Bt Cotton
“Golden rice” planned in Asia, was the other example of a Genetically Modified crop that genetically produced nearly 20 times the beta carotene of existing varieties. It was created by including a gene from daffodil Narcissus pseudonarcissus and bacterium Erwinia uredovora which produces an enzyme called phyotene synthase and phyotene desaturase respectively. The introduction of these genes enabled beta carotene to be converted to vitamin A in the human liver, thereby increasing the amount of beta carotene available for vitamin A synthesis in the body. Another type of rice was produced to fight iron deficiency. This GM crop was generated by introducing a ferritin rich genome from a common bean, Phaseolus vulgaris which produces a protein that can bind to iron and as well as a gene from the fungus Aspergillus fumigatus which produce an enzyme that is capable of digesting enzymes, thereby resulting in an increase of iron availability via digestion of phytate.
2. GMOs in plants:
GM animals and plants are being transformed to generate safer and cheaper vaccines and therapeutics. For example, hepatitis B vaccines have been generated by isolating GM Escherichia coli and GM Baker’s yeast to injectable insulin, Factor VII for Hemophiliacs, and Tissue Plasminogen Activator(tPA) for heart attack and stroke patients. Moreover, GM plants also produce “edible vaccines”. An edible vaccine is an antigenic protein introduced in the edible parts of the fruit, that is absorbed into the bloodstream when consumed. Once absorbed these proteins stimulate the immune system to produce antibodies against the pathogen from which the antigen was derived. Such vaccines are safe, cheap, and painless. These have to be introduced in developing countries where there is no facility for refrigeration and availability of sterile needles.
3. Genetic Modifications in humans:
Genetic Modifications in humans are done by gene therapy. It is a great treatment option, ranging from uncommon metabolic disorders to cancers. Another example is the coupling of stem cell therapy with recombinant DNA methods that allows stem cells derived from a patient to the desired gene. For example, a normal beta-globin gene may be introduced into the DNA of the bone marrow of a sickle cell anemia patient, introducing these cells into the patient could cure the disease without even the need of a matched donor.
4. GMOs in environmental management:
Another use of GMOs is in environmental management. For example, some bacteria can degrade plastics, if these bacteria are cultured in-vitro and are implemented on a large scale, they can be used as a substitute for plastics. In the 1990s, a British company, Zeneca generated microbially produced biodegradable plastic, Biopol (polyhydroxyalkanoate, PHA). A Genetically Modified bacterium, Ralstonia eutropha, which converts glucose and a variety of organic acids into a polymer, generates biodegradable plastic. GM bacteria have also shown the ability to metabolize oil and heavy metals that may provide a very efficient strategy for bioremediation.
Genetic researchers believe it can cure diseases and ameliorate suffering, but some people think that using gene therapy may generate “designer children” and increase human lifespan, which may affect sustainable development. Though GMOs have benefited human society in many ways, some disadvantages exist, therefore, the production of GMOs is believed to be a highly controversial topic in many parts of the world. But it can resolve scientific, medical, and environmental issues if used justifiably.
Dept. of Biochemistry and Biotechnology
St. Xavier's College, Ahmedabad
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Fridovich-Keil, J. L. and Diaz, . Julia M. (2021, May 1). Genetically modified organism. Encyclopedia Britannica. https://www.britannica.com/science/genetically-modified-organism