Chapter 10. Genetically Modified Organism: Benefits and Concerns

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1 Chapter 10 Genetically Modified Organism: Benefits and Concerns Introduction Genetically Modified Organism (GMO) is an organism that possesses genetic material altered using genetic engineering techniques. The first GMO was produced a few decades ago and many GMOs are widely used at present, especially in medicals, industry and agriculture. However, many concerns of using GMOs as food and impacts on environment are raised. This chapter provides information about basic principle of GMOs, benefits, concerns, validity and global situation of GMOs and their situation in Thailand in order to create right attitude towards GMOs. DNA and Gene DNA (Deoxyribonucleic acid) is genetic material in cells of any organisms. It encodes genetic instructions for life. Most organisms have DNA as genetic materials. DNA consists of four types of nucleotides, A, C, T and G. Each species differs in numbers and orders of nucleotides. Gene is a region of DNA that encodes for RNA or protein and determines traits of an organism. Gene is inherited from parents to progeny. Each gene encodes for a specific functional protein. In all organisms, gene works in the same manner. Genetic code in DNA is transcribed into RNA and genetic code in RNA is translated to protein. Each protein plays a specific role such as enzyme in metabolic process, protein in cell structure, etc. Therefore, genes determine characters. As all genes work in the same way, we can cut the gene from any species and insert it into another species. For example, insulin gene from human was cut and ligated into bacteria and, therefore, bacteria produce insulin hormone. Insulin for diabetes treatment is mainly produced by this method. Genetic Engineering Knowledge about chemical property of DNA, DNA structure, function of genes including finding of enzymes that can cut and ligate DNA leads to technique called genetic engineering. In short, genetic engineering is a technique to cut and ligate DNA. Cutting a gene from one species and transferring the gene into another species generate new organism with desired trait.

2 Restriction enzyme is an enzyme that can cut DNA or gene at specific site. It is compared as scissors. There are many types of restriction enzyme, for example, EcoRI, HindIII, BamHI and AluI. DNA ligase is an enzyme that can ligate DNA or gene. It is compared as glue to connect DNA or gene together. New organism with desired trait generated by genetic engineering is called genetically modified organism (GMO), which can be bacteria, microorganisms, plants or animals. Other words of genetically modified plant are transgenic plant and biotech crop. Genetically modified animal is also called as transgenic animal. There are five steps of genetic engineering technique. 1. Preparation of gene of interest that encodes for novel trait. 2. Preparation of DNA vector such as plasmid, which is circular DNA that acts as vehicle to carry gene of interest into another host genome. 3. Cutting of a gene of interest and DNA vector using restriction enzyme and ligating the gene of interest into DNA vector to become recombinant DNA. 4. Transformation of recombinant DNA into genome of another organism s cells (host cells). 5. Selection of host cell containing gene of interest. Selected host cell is then cultured to become genetically modified organism (GMO). In the beginning, GMOs were bacteria and microorganisms to produce desired proteins such as medicines or enzymes, for example, insulin hormone for diabetes treatment and hepatitis B vaccine, enzyme in cheeses-making process and enzyme in washing powder. Furthermore, living genetically modified bacteria are used in eliminating of metals in soil, waste from industrial factory and oil slick in the sea. Genetically modified plants (Transgenic plants) Conventional plant breeding uses two plants as male and female which has to be the same or very closely related species. It can also take a long time to achieve desired traits. Some characteristics of interest may not exist in any same or related species. This cross breeding makes several genes exchange between two plants to produce offspring.

3 Then, the desired results may not be achieved and sometimes may lose some good original characteristics. On the other hand, genetic engineering technique enables to bring useful genes from a wide range of organisms, not only from same or closely related species. This powerful tool allows the modification of desired genes specifically to generate superior plant varieties quickly and effectively. The two major methods to produce genetically modified plants have been developed. First, the method is based on utilizing bacteria named Agrobacterium tumefaciens. The other method is called particle bombardment (biolistics) or gene gun which is effective direct gene-transfer method. Agrobacterium tumefaciens has the ability to transfer the gene into the plant genome. The gene of interest has to be genetic engineered by cutting and joining into the plasmid vector, and then transferring the recombinant vector into Agrobacterium tumefaciens. Subsequently, the gene of interest has been transferred into plant genome by Agrobacterium. The transformed plant cells were subjected to tissue culture techniques until regenerated to transgenic plants which have desirable characteristics. For particle bombardment method, small gold particles about 1-2 micrometers are coated with the DNA that is to be transferred into plant cells or tissues. The DNA-coated particles are inserted into the particle bombardment apparatus and are propelled at high speed into target plant tissues. After that, the plant tissues are cultured, selected, and regenerated to transgenic plants. Examples of genetically modified plants are Roundup ready soybeans which are tolerant to glyphosate (herbicide), Bt corn which is resistant to insects (Figure 1), Bt cotton (insect-resistant cotton), golden rice which produces vitamin A, Flav Savr TM tomatoes which delay ripening, PRSV resistant papaya which is resistant to papaya ringspot virus (PRSV), blue roses which exhibit blue flower, and transgenic corns producing pharmaceuticals.

4 Bacillus thuringiensis Figure 1 Production of Bt corn which is genetically engineered for insect-resistance. A gene from the bacteria, Bacillus thuringiensis (Bt), encoding proteins toxic to European corn borer. The Bt corns are resistant to larvae and insects, resulting in the reduction of insecticide use. Hall, 2013 [Online]. Global status of genetically modified crops Industrial and developing countries have grown genetically modified crops or transgenic crops or now more often called biotech crops increasingly every year. The rapid adoption of biotech crops since the first year of commercialization in 1996 to 2015 reflects the benefits realized by farmers. The International Service for the Acquisition of Agri-biotech Applications (ISAAA) reported in 2015 that 28 countries have planted biotech crops. The US has continued to be the lead country for planting biotech crops. The second largest grower globally is Brazil, followed by Argentina, India, and Canada, respectively. The principal biotech crops grown globally are soybeans, maize, cottons, and canola. In addition, 40 countries allow the import of biotech crops for food and feed. Biotech crops were approved in 2015 and planned for commercialization in 2016 and beyond in several countries. In Argentina, a drought tolerant soybean and a virus-resistant potatoes were approved. In Brazil, approval was gained for cultivation of a high yield eucalyptus, a virus-resistant bean, and a new herbicide tolerant soybean. In Myanmar, a new Bt cotton variety was commercialized in In Canada, a high quality non-browning apple was approved. The approval has been shifted towards more food crops, including

5 white maize in South Africa; sugar beet and sweet corn in US and Canada; papaya, squash, potato, and apple in US; papaya in China; and Bt eggplant in Bangldesh. In addition, Vietnam planted a stacked Bt and herbicide-tolerant maize for the first time in 2015 (James, 2015). Brookes and Barfort (2012) in Global impact of biotech crop indicated that biotech crops have contributed to a significant reduction in the use of insecticides and herbicides since In the present circumstances, the arable lands have been limited and the world s population has been increasing rapidly, so it is important to increase the productivity. Biotech crops are already contributing to help by increasing productivity and coincidentally decreasing cost of production as a result of reduced need for inputs (such as decreasing use of chemicals) (James, 2015). In the future, it tends to be integrated agriculture i.e. organic agriculture and biotech crops based on the scientific knowledge. Transgenic animals The production of transgenic animals is a slow, tedious, and expensive process. After genetically engineering the gene of interest into the vector, the recombinant DNA is injected into nucleus of a fertilized oocyte, this technique called microinjection or pronuclear microinjection. The oocyte is then implanted in oviduct of a surrogate mother (Figure 2). There are several purpose of genetic modification of animals. Transgenic animals are used as experimental models to research human diseases. Many transgenic animals have been developed to produce human therapeutics or tissue for implantation, to enhance production or food quality characteristics such as faster growing fish, pigs that digest food more efficiently, and to improve animal health (e.g. disease resistance). Transgenic animals have been developed to produce human proteins used in medical treatments, such as transgenic goat, sheep, pigs, and rats. Genetically modified fish have been developed with an over-production of growth hormone. This has enhanced dramatic growth in several species, including salmon, trout, and tilapia. Enviropig was genetically engineered to have capability of digesting plant phosphorus more efficiently than conventional pigs. These pigs excrete less phosphorous and would reduce water pollution. The scientists generated genetically modified cows with human

6 genes which produce milk that would be the same as human breast milk. In addition, genetically engineered goat can produce strong spiderweb-like silk proteins in their milk which are strong and elastic. In the future, the spider milk would be used for military and medical applications. Figure 2 Creating a transgenic animal using microinjection technique. The gene of interest is injected into the nucleus of a fertilized egg. The egg is then implanted in the oviduct of a surrogate. Genetic Engineering, 2013 [Online]. GMOs and public concerns Several GM products e.g., insulin, hepatitis B vaccine and etc., have been widely and commercially utilized in food industry, pharmaceutical industry and etc. However, the use of GM products like GM plants or GM crops for food arises certain public concerns in health, environment and economy. Health concerns Concern in antibiotic resistance According to the method for creating GM crops, antibiotic-resistance genes have been used as the selectable marker. Therefore, there is concern that the antibioticresistance genes from GM crops might be transmitted to bacteria in human gut, causing

7 antibiotic-resistant microbes and consequently it is unable to cure those who consume GM foods using antibiotics. However, scientific data indicated that the possibility of introgression of antibiotic-resistance gene to bacteria in human tract is very low, and currently there is no experimental and reliable evidence of introgression of antibiotic-resistance genes from GM crops to bacteria in human gut yet. Moreover, regarding to this concern, other kinds of selectable genes, like GFP (green fluorescence protein) gene, have been used instead of antibiotic-resistance genes in the process of creating GM crops. Concern in allergenicity and toxicity Since GM crops obtaining the desired gene from other organisms, the allergens and toxins might be generated from transgenic plants or crops. Hence, GM crops need to be analyzed and meet the food safety requirement of U.S. Food and Drug Administration (USFDA). The analysis includes study in possibility of new components/proteins from GM crops to be allergens in human, examination of stability of the new protein in various conditions e.g., ph, temperature and imitated digestive system of human or mammals, and study on toxicity of the new protein in mouse. So far, there is no evidence that the new protein produced from any GM crops have caused allergy or diseases in GM crop consumers. Environmental concerns Concern of Bt crops to non-target insects There is concern that Bt toxin from Bt crops could be harmful to non-target, useful insects, mammals, human, and any animals in ecosystem. However, negative impact of Bt crops on biodiversity has not been found yet. Concern about resistance to Bt toxin and herbicide resistance Insects could naturally adapt and be resistant to Bt toxin. Hence, cultivation of Bt crops together with original crops might be slow down the resistance rate of target insects to Bt toxin. Moreover, weeds could also naturally adapt and be resistant to herbicide. Therefore, this could raise another concern of GM crops to environmental impact. Concern in gene transmission

8 There is concern that an insecticide- or herbicide-resistance gene from GM crops probably transmits from GM crops to wild species or related species. To prevent this phenomena, many strategies are applied, for example, the generation of a GM crop with the transgene that could not be transmitted through plant pollens, manipulation of GM flowers to have flowering time slower than that of original crops or cultivation of GM crops in the restricted area and away from the original crops. Economic concerns Most patents about agricultural technologies including GM patents belong to big companies. Farmer, therefore, would be forced to buy seeds in every season from the seed company. The cooperation between a private company and a developing country to generate GM crops might solve the above problem. Moreover, developing countries should develop their own technologies or GM crops for their own sake and for their sustainable agriculture. As the consumers have the right to choose their own foods, so, many countries including Thailand and EU countries, require labeling of GM foods with a labeling threshold of 1% or 5% GM content by weight. Food safety assessment of GMOs As many controversy about GMOs, the strict system on food safety assessment of GMOs is necessary. The food safety assessment of GMOs is evaluated based on substantial equivalence principle. The GM crops/foods will be compared with traditional crops/foods in the following criteria; 1) general information of GM crops considering about transgenes, new proteins and new metabolites, 2) nutrition - nutrition of GM crops must be equal or comparable to that of traditional crops 3) toxicity and 4) allergenicity. The new protein from GM crops must not be toxic to mouse and be allergen to human. Once the food safety assessment of the GM crops is approved, the crops will be able to distribute to farmers or markets. Detection of GMOs or products containing GM ingredient (s) Many GM crops/products such as Roundup ready soybean, Bt corn, Flav Savr TM, tomato and PRSV resistant papaya, which are approved on the food safety assessment, have

9 been commercially sold in many countries e.g., U.S.A., European countries, Japan, and Canada. However, detection of GMOs is still needed to clarify between GMOs and non- GMOs. The method for GMOs detection is based on DNA and protein assay. Protein-based method uses enzyme-linked immunosorbant assay (ELISA) technique or western blotting technique to detect the additional protein that encoded from the transgene in GMOs. However, in case of processed GM products whose protein are denature or not in the functional form, the detection of GM products is not possible using this method. DNA-based method examines the marker gene or transgene that is transferred to host plants. This method employs polymerase chain reaction (PCR) technique which is the method to amplify the target gene in vitro. Moreover, real time PCR can be performed to quantify the amount of GMOs in the product as well. In labeling of GMOs, the product containing GMOs more than 1 percent or 5 percents, depending on countries, are required to notify to customer. National Center for Genetic Engineering and Biotechnology (BIOTEC), Department of Agriculture, Department of Medical Science are the institutes that provide services for GMOs detection in Thailand. Status of genetically modified organisms in Thailand In Thailand, genetically modified organisms, especially plants, are prohibited for business but they are allowed for research. Importing genetically modified plant needs approval from Department of Agriculture. GMO food safety is assessed by Food and Drug Administration (FDA), Ministry of public health, before on sale. References ไคล ฟ เจมส สถานภาพการผล ตพ ชเทคโนโลย ช วภาพ / พ ชจ เอ มในเช งการค าท วโลก [ระบบออนไลน ]. แหล งท มา (8 ส งหาคม 2554). ปร นทร ช ยว ส ทธางก ล จ เอ มโอ. กร งเทพฯ: สาน กพ มพ ค ร สภาลาดพร าว. 265 น. เร องน าร เก ยวก บการด ดแปลงพ นธ กรรมของส งม ช ว ต [ระบบออนไลน ]. แหล งท มา (22 ต ลาคม 2556).

10 ส ร นทร ป ยะโชคณาก ล พ นธ ว ศวกรรมเบ องต น. กร งเทพฯ: ส าน กพ มพ มหาว ทยาล ยเกษตรศาสตร. 282 น. Brookes and Barfort Global impact of biotech crops. GM crops and Food: Biotechnology in Agriculture and the Food Chain. 3: Genetic Engineering: Application-Animal Biotechnology: Transgenic animals: [Online]. Available Application-Animal_Biotechnology.htm (22 October 2013). Genetically modified organism [Online]. Available. (22 May 2016). Hall H BT corn: Is it worth the risk?. [Online]. Available (21 May 2016). Nicolia A., Manzo A., Veronesi F. and Roselline D An overview of the last 10 years of genetically engineered crop safety research. [Online]. Available pdf (7 July 2014).