Genetically Modified Organisms
Genetic modification of plants and animals continue to steer serious public debate regarding the safety of use and a multitude of ethical and moral dilemmas. However, despite ongoing discussion general public remains mostly unaware of the nature and particular aspects of the genetic engineering of organisms and its implications. Genetically engineered plants and animals can provide significant benefits regarding boost in food production and development of new drugs. Needless to say, there are also concerns regarding the environmental safety of using genetically modified organisms and risks to human health. While public campaigns tend to overemphasize health risks of genetically modified organisms, it is necessary the arguments they provide are rarely supported by firm scientific evidence. This paper will provide an explanation of the mechanism behind genetic engineering as well as provide information on controversial aspects of it.
First of all, it is necessary to understand why genetically modified organisms (GMOs) have been created and what purposes they serve. GMOs can be characterized as any organism in which the genome or DNA has been intentionally modified in a way that would have been impossible under natural conditions such as recombination or mating (Key, Ma, & Drake, 2008). GM crops and animals are developed mostly because of perceived advantages and benefits of such organisms over their non-genetically modified counterparts. Application of genetic engineering is argued to result in a product with a lower price for consumers and greater benefits overall. When it comes to plants, the objective of genetic modification was to enhance crop protection from natural pests and pathogens while also increasing the yield.
Currently, low crop yields considered to be a global challenge as pathogens, herbivorous insects and parasites undermine productivity of crops. Plants can be modified to resist insects by incorporating a gene responsible for producing a toxin that acts as an insecticide. Additionally, genetic modification of plants can help to combat abiotic stress, more specifically drought, rising temperatures and ground salinity. Genetic modification of animals perceives similar goals aiming at enhancing qualities of the livestock. Moreover, microorganisms can also be modified to suffice human needs, more specifically, some strains of bacteria have been genetically engineered to produce human insulin.
There are several techniques available for genetic modification of crops and other domestic animals. Microbial vector is one of the well-established methods genetic engineering that is using naturally occurring Agrobacterium tumefaciens bacteria to introduce genetic alterations to target organisms. Agrobacterium is a pathogen causing gall diseases in several species of plants. Unlike most of other pathogens, it transfers a portion of its genome into the host cells (Safety of genetically engineered foods, 2004). The transferred fragment of DNA are integrated into the genome of the host and can be expressed as if they were of an original host’s genome. It is possible to substitute the DNA from A. tumefaciens responsible for the gall diseases with the DNA of interest in laboratory conditions (Dekkers & Hospital, 2002). Thus, new strains of Agrobacterium are created in order to deliver, and stably integrate new genetic materials to a range of crops the there originally susceptible to Agrobacterium.
Microprojectile bombardment is a method that utilizes microscopic pellets with adhered DNA that is propelled at plant cells. While the method is rather crude and inefficient, it proved to be effective at modifying such crops as corn, rice, and other cereal grains that may not be augmented using Agrobacterium mentioned above (Dekkers & Hospital, 2002). Plant cells can be stripped off of their protective membrane using electroporation method (Safety of genetically engineered foods, 2004). Plant cells could be turned into protoplasts that can then accept new DNA from a culture medium when an electrical impulse destabilizes their membranes facilitating the entrance of macromolecules into the cell. Once transformed the cells can be regretted resulting in new transgenic plant culture. Additionally, microinjection of the DNA of interest into anchored cells is also performed.
When it comes to genetic modification of animals scientists, employ such methods as retroviral vectors, transfection, and knock-in and knock-out technology. Some of the methods of gene engineering of animals closely resemble those used to augment plant cells (Dekkers & Hospital, 2002). Electroporation and microinjections of DNA are commonly used for means of genetic manipulations involving animals cells. Retroviral vectors as techniques involve the use of virus strains that carry genetic material for introduction into the host cell’s genome (Dekkers & Hospital, 2002). Knock-in and knock-out method characterized by replacement of existing genes by those that have been specially engineered.
Genetically modified foods are rather common these days considering that most of the common crops have been modified to make them less prone to pests (Bawa & Anilakumar, 2012). The range of foods and products containing GMOs that are available to condiments in local supermarkets contain some of the basic foods and ingredients. In the United States almost 85 percent of domestically grown corn is genetically modified. Producers prefer to modify corn to make resistant to herbicides used to kill weeds. Soy is also among the most genetically modified crops; it was modified to have higher levels of oleic acids naturally found in olive trees. Sugar may also come from genetically modified plants that were enhanced to better resist glyphosate. Milk may also come from cows with inserted recombined bovine growth hormone that leads to increasing in milk production. Various other foods such as canola, papaya, potato, and maize commonly found in stores may have been genetically modified. The increasing number of foods that contain genetic augmentation raises concerns among consumers regarding their safety for human health.
GM crops and domestic animals should not pose any immediate intrinsic risks to human health just because there are the foreign fragment of DNA present within them (Safety of genetically engineered foods, 2004). However, there is still little comprehensive data regarding long-term effects of consuming GMOs leading to serious speculations about GM foods. GM foods have been consumed in large quantities by millions of people around the world for almost two decades with no evidence of ill effects (Key, Ma, & Drake, 2008). Some of the studies have claimed to show an association between GM food consumption and detrimental effects to health. For example, in 1999 a study claimed that rat fed with a genetically modified potato that contained genes for specific lectin showed signs of damage to their gut mucosa. However, the study proved to be ill-designed and as such that contained numerous flaws in its design.
The main concern of GMOs consumption rises from a possibility of intoxication by proteins produced as a result of foreign gene expression. Such intoxication can take place if a toxin coded by the transgenes would have been systematically absorbed by the host. That is why potential toxicity of proteins is thoroughly screened and assessed (Safety of genetically engineered foods, 2004). For example, GM tomatoes that contained foreign genes of B. thuringiensis resulting in expression of toxins were assessed and compared to parent tomatoes. GM tomatoes showed no serious alterations in contents of vitamins, minerals, proteins and levels of toxic glycoalkaloids (Key, Ma, & Drake, 2008). In toxicity studies on rats that were tube-fed with this GM tomatoes, toxic effects were also not observed. Thus, considering such results of tests GM and parent tomato can be characterized as equivalent.
Another commonly expressed concern regards GMOs is the allergenicity of modified organisms. Considering that allergies to fruits and vegetables are widespread it is reasonable to pressmen that GM varieties can be potentially allergenic (Bawa & Anilakumar, 2012). There two primary factors pertaining to the fear of allergenic properties of GMOs: a chance that genes from known allergens will be introduced to crops that have not been typically considered as widely allergenic or that new allergens may be created as a result of changed expression of endogenous proteins (Key, Ma, & Drake, 2008). The allergenic potential was found in some GM crops during tests signifying the efficacy of assessment procedure that prevents potentially harmful products from being commercially realized. Thus, it is possible to say that GM can be regarded as generally safe though more studies are required considering the relative novelty of GMOs.
The development and marketing of GMOs are thoroughly regulated in the United States. The United States Food and Drug Administration (FDA) is the primary governmental body responsible for regulation and approval of GM crops and domestic animals (“Food from Genetically Engineered Plants”, 2016). The Environmental Protection Agency (EPA) and the United States Department of Agriculture also partakes in an establishment of regulations regarding GMOs. Currently, there are no federal laws in the United States that specifically regulate GMOs (“Food from Genetically Engineered Plants”, 2016). Instead, these foods are regulated by norms established for conventional products. In the policy published in 1992, the FDA had established principles that regulation should emphasise the nature of the product rather than the particular aspects of its production. The safe use of pesticides including transgenic modifications is regulated by the EPA. The prevalent majority of bioengineered plants are also subject to regulation by the Animal and Plant Health Inspection Service (APHIS).
To conclude everything mentioned above, GMOs represent the remarkable scientific achievement with the potential to greatly enhance food and drug production. Genetic modification of plants and animals can be performed through a variety of techniques. The resulting GM plants and animals have enhanced characteristics that could not occur naturally. While considered safe for human health GMOs still raise public debates. Further comprehensive studies are required to better understand the long-term effects of GMOs consumption.