For a non-technical introduction to the topic of genetics, see Introduction to genetics. For the song by Orchestral Manoeuvres in the Dark, see Genetic Engineering (song).
Genetic engineering, also called genetic modification or genetic manipulation, is the direct manipulation of an organism's genes using biotechnology. It is a set of technologies used to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms. New DNA is obtained by either isolating and copying the genetic material of interest using recombinant DNA methods or by artificially synthesising the DNA. A construct is usually created and used to insert this DNA into the host organism. The first recombinant DNA molecule was made by Paul Berg in 1972 by combining DNA from the monkey virus SV40 with the lambda virus. As well as inserting genes, the process can be used to remove, or "knock out", genes. The new DNA can be inserted randomly, or targeted to a specific part of the genome.
An organism that is generated through genetic engineering is considered to be genetically modified (GM) and the resulting entity is a genetically modified organism (GMO). The first GMO was a bacterium generated by Herbert Boyer and Stanley Cohen in 1973. Rudolf Jaenisch created the first GM animal when he inserted foreign DNA into a mouse in 1974. The first company to focus on genetic engineering, Genentech, was founded in 1976 and started the production of human proteins. Genetically engineered human insulin was produced in 1978 and insulin-producing bacteria were commercialised in 1982. Genetically modified food has been sold since 1994, with the release of the Flavr Savr tomato. The Flavr Savr was engineered to have a longer shelf life, but most current GM crops are modified to increase resistance to insects and herbicides. GloFish, the first GMO designed as a pet, was sold in the United States in December 2003. In 2016 salmon modified with a growth hormone were sold.
Genetic engineering has been applied in numerous fields including research, medicine, industrial biotechnology and agriculture. In research GMOs are used to study gene function and expression through loss of function, gain of function, tracking and expression experiments. By knocking out genes responsible for certain conditions it is possible to create animal model organisms of human diseases. As well as producing hormones, vaccines and other drugs genetic engineering has the potential to cure genetic diseases through gene therapy. The same techniques that are used to produce drugs can also have industrial applications such as producing enzymes for laundry detergent, cheeses and other products.
The rise of commercialised genetically modified crops has provided economic benefit to farmers in many different countries, but has also been the source of most of the controversy surrounding the technology. This has been present since its early use, the first field trials were destroyed by anti-GM activists. Although there is a scientific consensus that currently available food derived from GM crops poses no greater risk to human health than conventional food, GM food safety is a leading concern with critics. Gene flow, impact on non-target organisms, control of the food supply and intellectual property rights have also been raised as potential issues. These concerns have led to the development of a regulatory framework, which started in 1975. It has led to an international treaty, the Cartagena Protocol on Biosafety, that was adopted in 2000. Individual countries have developed their own regulatory systems regarding GMOs, with the most marked differences occurring between the USA and Europe.
Genetic engineering is a process that alters the genetic make-up of an organism by either removing or introducing DNA. Unlike traditionally animal and plant breeding, which involves doing multiple crosses and then selecting for the organism with the desired phenotype, genetic engineering takes the gene directly from one organism and inserts it in the other. This is much faster, can be used to insert any genes from any organism (even ones from different domains) and prevents other undesirable genes from also being added.
Genetic engineering could potentially fix severe genetic disorders in humans by replacing the defective gene with a functioning one. It is an important tool in research that allows the function of specific genes to be studied. Drugs, vaccines and other products have been harvested from organisms engineered to produce them.Crops have been developed that aid food security by increasing yield, nutritional value and tolerance to environmental stresses.
The DNA can be introduced directly into the host organism or into a cell that is then fused or hybridised with the host. This relies on recombinant nucleic acid techniques to form new combinations of heritable genetic material followed by the incorporation of that material either indirectly through a vector system or directly through micro-injection, macro-injection or micro-encapsulation.
Genetic engineering does not normally include traditional breeding, in vitro fertilisation, induction of polyploidy, mutagenesis and cell fusion techniques that do not use recombinant nucleic acids or a genetically modified organism in the process. However, some broad definitions of genetic engineering include selective breeding.Cloning and stem cell research, although not considered genetic engineering, are closely related and genetic engineering can be used within them.Synthetic biology is an emerging discipline that takes genetic engineering a step further by introducing artificially synthesised material into an organism.
Plants, animals or micro organisms that have been changed through genetic engineering are termed genetically modified organisms or GMOs. If genetic material from another species is added to the host, the resulting organism is called transgenic. If genetic material from the same species or a species that can naturally breed with the host is used the resulting organism is called cisgenic. If genetic engineering is used to remove genetic material from the target organism the resulting organism is termed a knockout organism. In Europe genetic modification is synonymous with genetic engineering while within the United States of America and Canada genetic modification can also be used to refer to more conventional breeding methods.
Main article: History of genetic engineering
Humans have altered the genomes of species for thousands of years through selective breeding, or artificial selection:1:1 as contrasted with natural selection, and more recently through mutagenesis. Genetic engineering as the direct manipulation of DNA by humans outside breeding and mutations has only existed since the 1970s. The term "genetic engineering" was first coined by Jack Williamson in his science fiction novel Dragon's Island, published in 1951 – one year before DNA's role in heredity was confirmed by Alfred Hershey and Martha Chase, and two years before James Watson and Francis Crick showed that the DNA molecule has a double-helix structure – though the general concept of direct genetic manipulation was explored in rudimentary form in Stanley G. Weinbaum's 1936 science fiction story Proteus Island.
In 1972, Paul Berg created the first recombinant DNA molecules by combining DNA from the monkey virus SV40 with that of the lambda virus. In 1973 Herbert Boyer and Stanley Cohen created the first transgenic organism by inserting antibiotic resistance genes into the plasmid of an Escherichia coli bacterium. A year later Rudolf Jaenisch created a transgenic mouse by introducing foreign DNA into its embryo, making it the world’s first transgenic animal. These achievements led to concerns in the scientific community about potential risks from genetic engineering, which were first discussed in depth at the Asilomar Conference in 1975. One of the main recommendations from this meeting was that government oversight of recombinant DNA research should be established until the technology was deemed safe.
In 1976 Genentech, the first genetic engineering company, was founded by Herbert Boyer and Robert Swanson and a year later the company produced a human protein (somatostatin) in E.coli. Genentech announced the production of genetically engineered human insulin in 1978. In 1980, the U.S. Supreme Court in the Diamond v. Chakrabarty case ruled that genetically altered life could be patented. The insulin produced by bacteria was approved for release by the Food and Drug Administration (FDA) in 1982.
In 1983, a biotech company, Advanced Genetic Sciences (AGS) applied for U.S. government authorisation to perform field tests with the ice-minus strain of Pseudomonas syringae to protect crops from frost, but environmental groups and protestors delayed the field tests for four years with legal challenges. In 1987, the ice-minus strain of P. syringae became the first genetically modified organism (GMO) to be released into the environment when a strawberry field and a potato field in California were sprayed with it. Both test fields were attacked by activist groups the night before the tests occurred: "The world's first trial site attracted the world's first field trasher".
The first field trials of genetically engineered plants occurred in France and the USA in 1986, tobacco plants were engineered to be resistant to herbicides. The People’s Republic of China was the first country to commercialise transgenic plants, introducing a virus-resistant tobacco in 1992. In 1994 Calgene attained approval to commercially release the first genetically modified food, the Flavr Savr, a tomato engineered to have a longer shelf life. In 1994, the European Union approved tobacco engineered to be resistant to the herbicide bromoxynil, making it the first genetically engineered crop commercialised in Europe. In 1995, Bt Potato was approved safe by the Environmental Protection Agency, after having been approved by the FDA, making it the first pesticide producing crop to be approved in the USA. In 2009 11 transgenic crops were grown commercially in 25 countries, the largest of which by area grown were the USA, Brazil, Argentina, India, Canada, China, Paraguay and South Africa.
In 2010, scientists at the J. Craig Venter Institute created the first synthetic genome and inserted it into an empty bacterial cell. The resulting bacterium, named Mycoplasma laboratorium, could replicate and produce proteins. Four years later this was taken a step further when bacterium was developed that replicated a plasmid containing a unique base pair, creating the first organism engineered to use an expanded genetic alphabet. In 2012, Jennifer Doudna and Emmanuelle Charpentier collaborated to develop the CRISPR/Cas9 system, a technique which can be used to easily and specifically alter the genome of almost any organism.
Main article: Genetic engineering techniques
Creating a GMO is a multi-step process. Genetic engineers must first choose what gene they wish to insert into the organism. This is driven by what the aim is for the resultant organism and is built on earlier research. Genetic screens can be carried out to determine potential genes and further tests then used to identify the best candidates. The development of microarrays, transcriptomes and genome sequencing has made it much easier to find suitable genes. Luck also plays its part; the round-up ready gene was discovered after scientists noticed a bacterium thriving in the presence of the herbicide.
Gene isolation and cloning
Main article: Molecular cloning
The next step is to isolate the candidate gene. The cell containing the gene is opened and the DNA is purified. The gene is separated by using restriction enzymes to cut the DNA into fragments or polymerase chain reaction (PCR) to amplify up the gene segment. These segments can then be extracted through gel electrophoresis. If the chosen gene or the donor organism's genome has been well studied it may already be accessible from a genetic library. If the DNA sequence is known, but no copies of the gene are available, it can also be artificially synthesised. Once isolated the gene is ligated into a plasmid that is then inserted into a bacterium. The plasmid is replicated when the bacteria divide, ensuring unlimited copies of the gene are available.
Before the gene is inserted into the target organism it must be combined with other genetic elements. These include a promoter and terminator region, which initiate and end transcription. A selectable marker gene is added, which in most cases confers antibiotic resistance, so researchers can easily determine which cells have been successfully transformed. The gene can also be modified at this stage for better expression or effectiveness. These manipulations are carried out using recombinant DNA techniques, such as restriction digests, ligations and molecular cloning.
Inserting DNA into the host genome
See also: Transformation (genetics), Transfection, and Transduction (genetics)
There are a number of techniques available for inserting the gene into the host genome. Some bacteria can naturally take up foreign DNA. This ability can be induced in other bacteria via stress (e.g. thermal or electric shock), which increases the cell membrane's permeability to DNA; up-taken DNA can either integrate with the genome or exist as extrachromosomal DNA. DNA is generally inserted into animal cells using microinjection, where it can be injected through the cell's nuclear envelope directly into the nucleus, or through the use of viral vectors.
In plants the DNA is often inserted using Agrobacterium-mediated recombination, taking advantage of the Agrobacteriums T-DNA sequence that allows natural insertion of genetic material into plant cells. Other methods include biolistics, where particles of gold or tungsten are coated with DNA and then shot into young plant cells, and electroporation, which involves using an electric shock to make the cell membrane permeable to plasmid DNA. Due to the damage caused to the cells and DNA the transformation efficiency of biolistics and electroporation is lower than agrobacterial transformation and microinjection.
As only a single cell is transformed with genetic material, the organism must be regenerated from that single cell. In plants this is accomplished through the use of tissue culture. In animals it is necessary to ensure that the inserted DNA is present in the embryonic stem cells. Bacteria consist of a single cell and reproduce clonally so regeneration is not necessary. Selectable markers are used to easily differentiate transformed from untransformed cells. These markers are usually present in the transgenic organism, although a number of strategies have been developed that can remove the selectable marker from the mature transgenic plant.
Further testing using PCR, Southern hybridization, and DNA sequencing is conducted to confirm that an organism contains the new gene. These tests can also confirm the chromosomal location and copy number of the inserted gene. The presence of the gene does not guarantee it will be expressed at appropriate levels in the target tissue so methods that look for and measure the gene products (RNA and protein) are also used. These include northern hybridisation, quantitative RT-PCR, Western blot, immunofluorescence, ELISA and phenotypic analysis.
The new genetic material can be inserted randomly within the host genome or targeted to a specific location. The technique of gene targeting uses homologous recombination to make desired changes to a specific endogenous gene. This tends to occur at a relatively low frequency in plants and animals and generally requires the use of selectable markers. The frequency of gene targeting can be greatly enhanced through genome editing. Genome editing uses artificially engineered nucleases that create specific double-stranded breaks at desired locations in the genome, and use the cell’s endogenous mechanisms to repair the induced break by the natural processes of homologous recombination and nonhomologous end-joining. There are four families of engineered nucleases: meganucleases,zinc finger nucleases,transcription activator-like effector nucleases (TALENs), and the Cas9-guideRNA system (adapted from CRISPR). TALEN and CRISPR are the two most commonly used and each has its own advantages. TALENs have greater target specificity, while CRISPR is easier to design and more efficient. In addition to enhancing gene targeting, engineered nucleases can be used to introduce mutations at endogenous genes that generate a gene knockout.
Genetic engineering has applications in medicine, research, industry and agriculture and can be used on a wide range of plants, animals and micro organisms. Bacteria, the first organisms to be genetically modified, can have plasmid DNA inserted containing new genes that code for medicines or enzymes that process food and other substrates. Plants have been modified for insect protection, herbicide resistance, virus resistance, enhanced nutrition, tolerance to environmental pressures and the production of edible vaccines. Most commercialised GMOs are insect resistant or herbicide tolerant crop plants. Genetically modified animals have been used for research, model animals and the production of agricultural or pharmaceutical products. The genetically modified animals include animals with genes knocked out, increased susceptibility to disease, hormones for extra growth and the ability to express proteins in their milk.
Genetic engineering has many applications to medicine that include the manufacturing of drugs, creation of model animals that mimic human conditions and gene therapy. One of the earliest uses of genetic engineering was to mass-produce human insulin in bacteria. This application has now been applied to, human growth hormones, follicle stimulating hormones (for treating infertility), human albumin, monoclonal antibodies, antihemophilic factors, vaccines and many other drugs. Mouse hybridomas, cells fused together to create monoclonal antibodies, have been adapted through genetic engineering to create human monoclonal antibodies. In 2017, genetic engineering of chimeric antigen receptors on a patient's own T-cells was approved by the U.S. FDA as a treatment for the cancer acute lymphoblastic leukemia. Genetically engineered viruses are being developed that can still confer immunity, but lack the infectioussequences.
Genetic engineering is also used to create animal models of human diseases. Genetically modified mice are the most common genetically engineered animal model. They have been used to study and model cancer (the oncomouse), obesity, heart disease, diabetes, arthritis, substance abuse, anxiety, aging and Parkinson disease. Potential cures can be tested against these mouse models. Also genetically modified pigs have been bred with the aim of increasing the success of pig to human organ transplantation.
Gene therapy is the genetic engineering of humans, generally by replacing defective genes with effective ones. Clinical research using somatic gene therapy has been conducted with several diseases, including X-linked SCID,chronic lymphocytic leukemia (CLL), and Parkinson's disease. In 2012, Alipogene tiparvovec became the first gene therapy treatment to be approved for clinical use. In 2015 a virus was used to insert a healthy gene into the skin cells of a boy suffering from a rare skin disease, epidermolysis bullosa, in order to grow, and then graft healthy skin onto 80 percent of the boy's body which was affected by the illness.Germline gene therapy would result in any change being inheritable, which has raised concerns within the scientific community. In 2015, CRISPR was used to edit the DNA of non-viable human embryos, leading scientists of major world academies to called for a moratorium on inheritable human genome edits. There are also concerns that the technology could be used not just for treatment, but for enhancement, modification or alteration of a human beings' appearance, adaptability, intelligence, character or behavior. The distinction between cure and enhancement can also be difficult to establish.
Researchers are altering the genome of pigs to induce the growth of human organs to be used in transplants. Scientists are creating "gene drives", changing the genomes of mosquitoes to make them immune to malaria, and then spreading the genetically altered mosquitoes throughout the mosquito population in the hopes of eliminating the disease.
Genetic engineering is an important tool for natural scientists. Genes and other genetic information from a wide range of organisms can be inserted into bacteria for storage and modification, creating genetically modified bacteria in the process. Bacteria are cheap, easy to grow, clonal, multiply quickly, relatively easy to transform and can be stored at -80 °C almost indefinitely. Once a gene is isolated it can be stored inside the bacteria providing an unlimited supply for research.
Organisms are genetically engineered to discover the functions of certain genes. This could be the effect on the phenotype of the organism, where the gene is expressed or what other genes it interacts with. These experiments generally involve loss of function, gain of function, tracking and expression.
- Loss of function experiments, such as in a gene knockout experiment, in which an organism is engineered to lack the activity of one or more genes. In a simple knockout a copy of the desired gene has been altered to make it non-functional. Embryonic stem cells incorporate the altered gene, which replaces the already present functional copy. These stem cells are injected into blastocysts, which are implanted into surrogate mothers. This allows the experimenter to analyse the defects caused by this mutation and thereby determine the role of particular genes. It is used especially frequently in developmental biology. When this is done by creating a library of genes with point mutations at every position in the area of interest, or even every position in the whole gene, this is called "scanning mutagenesis". The simplest method, and the first to be used, is "alanine scanning", where every position in turn is mutated to the unreactive amino acid alanine.
- Gain of function experiments, the logical counterpart of knockouts. These are sometimes performed in conjunction with knockout experiments to more finely establish the function of the desired gene. The process is much the same as that in knockout engineering, except that the construct is designed to increase the function of the gene, usually by providing extra copies of the gene or inducing synthesis of the protein more frequently. Gain of function is used to tell whether or not a protein is sufficient for a function, but does not always mean it's required, especially when dealing with genetic or functional redundancy.
- Tracking experiments, which seek to gain information about the localisation and interaction of the desired protein. One way to do this is to replace the wild-type gene with a 'fusion' gene, which is a juxtaposition of the wild-type gene with a reporting element such as green fluorescent protein (GFP) that will allow easy visualisation of the products of the genetic modification. While this is a useful technique, the manipulation can destroy the function of the gene, creating secondary effects and possibly calling into question the results of the experiment. More sophisticated techniques are now in development that can track protein products without mitigating their function, such as the addition of small sequences that will serve as binding motifs to monoclonal antibodies.
- Expression studies aim to discover where and when specific proteins are produced. In these experiments, the DNA sequence before the DNA that codes for a protein, known as a gene's promoter, is reintroduced into an organism with the protein coding region replaced by a reporter gene such as GFP or an enzyme that catalyses the production of a dye. Thus the time and place where a particular protein is produced can be observed. Expression studies can be taken a step further by altering the promoter to find which pieces are crucial for the proper expression of the gene and are actually bound by transcription factor proteins; this process is known as promoter bashing.
Organisms can have their cells transformed with a gene coding for a useful protein, such as an enzyme, so that they will overexpress the desired protein. Mass quantities of the protein can then be manufactured by growing the transformed organism in bioreactor equipment using industrial fermentation, and then purifying the protein. Some genes do not work well in bacteria, so yeast, insect cells or mammalians cells can also be used. These techniques are used to produce medicines such as insulin, human growth hormone, and vaccines, supplements such as tryptophan, aid in the production of food (chymosin in cheese making) and fuels. Other applications with genetically engineered bacteria could involve making them perform tasks outside their natural cycle, such as making biofuels, cleaning up oil spills, carbon and other toxic waste and detecting arsenic in drinking water. Certain genetically modified microbes can also be used in biomining and bioremediation, due to their ability to extract heavy metals from their environment and incorporate them into compounds that are more easily recoverable.
In materials science, a genetically modified virus has been used in a research laboratory as a scaffold for assembling a more environmentally friendly lithium-ion battery. Bacteria have also been engineered to function as sensors by expressing a fluorescent protein under certain environmental conditions.
Main articles: Genetically modified crops and Genetically modified food
One of the best-known and controversial applications of genetic engineering is the creation and use of genetically modified crops or genetically modified livestock to produce genetically modified food. Crops have been developed to increase production, increase tolerance to abiotic stresses, alter the composition of the food, or to produce novel products.
The first crops to be realised commercially on a large scale provided protection from insect pests or tolerance to herbicides. Fungal and virus resistant crops have also being developed or are in development. This make the insect and weed management of crops easier and can indirectly increase crop yield. GM crops that directly improve yield by accelerating growth or making the plant more hardy (by improving salt, cold or drought tolerance) are also under development. In 2016 Salmon have been genetically modified with growth hormones to reach normal adult size much faster.
GMOs have been developed that modify the quality of produce by increasing the nutritional value or providing more industrially useful qualities or quantities. The Amflora potato produces a more industrially useful blend of starches. Soybeans and canola have been genetically modified to produce more healthy oils. The first commercialised GM food was a tomato that had delayed ripening, increasing its shelf life.
Plants and animals have been engineered to produce materials they do not normally make. Pharming uses crops and animals as bioreactors to produce vaccines, drug intermediates, or the drugs themselves; the useful product is purified from the harvest and then used in the standard pharmaceutical production process. Cows and goats have been engineered to express drugs and other proteins in their milk, and in 2009 the FDA approved a drug produced in goat milk.
Genetic engineering has potential applications in conservation and natural area management. Gene transfer through viral vectors has been proposed as a means of controlling invasive species as well as vaccinating threatened fauna from disease. Transgenic trees have been suggested as a way to confer resistance to pathogens in wild populations. With the increasing risks of maladaptation in organisms as a result of climate change and other perturbations, facilitated adaptation through gene tweaking could be one solution to reducing extinction risks. Applications of genetic engineering in conservation are thus far mostly theoretical and have yet to be put into practice.
Genetic engineering is also being used to create microbial art. Some bacteria have been genetically engineered to create black and white photographs. Novelty items such as lavender-colored carnations,blue roses, and glowing fish have also been produced through genetic engineering.
Main article: Regulation of genetic engineering
The regulation of genetic engineering concerns the approaches taken by governments to assess and manage the risks associated with the development and release of GMOs. The development of a regulatory framework began in 1975, at Asilomar, California. The Asilomar meeting recommended a set of voluntary guidelines regarding the use of recombinant technology. As the technology improved USA established a committee at the Office of Science and Technology, which assigned regulatory approval of GM plants to the USDA, FDA and EPA. The Cartagena Protocol on Biosafety, an international treaty that governs the transfer, handling, and use of GMOs, was adopted on 29 January 2000. One hundred and fifty-seven countries are members of the Protocol and many use it as a reference point for their own regulations.
The legal and regulatory status of GM foods varies by country, with some nations banning or restricting them, and others permitting them with widely differing degrees of regulation. Some countries allow the import of GM food with authorisation, but either do not allow its cultivation (Russia, Norway, Israel) or have provisions for cultivation, but no GM products are yet produced (Japan, South Korea). Most countries that do not allow for GMO cultivation do permit research. Some of the most marked differences occurring between the USA and Europe. The US policy focuses on the product (not the process), only looks at verifiable scientific risks and uses the concept of substantial equivalence. The European Union by contrast has possibly the most stringent GMO regulations in the world. All GMOs, along with irradiated food, are considered "new food" and subject to extensive, case-by-case, science-based food evaluation by the European Food Safety Authority. The criteria for authorisation fall in four broad categories: "safety," "freedom of choice," "labelling," and "traceability." The level of regulation in other countries that cultivate GMOs lie in between Europe and the United States.
One of the key issues concerning regulators is whether GM products should be labeled. The European Commission says that mandatory labeling and traceability are needed to allow for informed choice, avoid potential false advertising and facilitate the withdrawal of products if adverse effects on health or the environment are discovered. The American Medical Association and the American Association for the Advancement of Science say that absent scientific evidence of harm even voluntary labeling is misleading and will falsely alarm consumers". Labeling of GMO products in the marketplace is required in 64 countries. Labeling can be mandatory up to a threshold GM content level (which varies between countries) or voluntary. In Canada and the USA labeling of GM food is voluntary, while in Europe all food (including processed food) or feed which contains greater than 0.9% of approved GMOs must be labelled.
Main article: Genetically modified food controversies
Critics have objected to the use of genetic engineering on several grounds, that include ethical, ecological and economic concerns. Many of these concerns involve GM crops and whether food produced from them is safe, whether it should be labeled and what impact growing them will have on the environment. These controversies have led to litigation, international trade disputes, and protests, and to restrictive regulation of commercial products in some countries.
Accusations that scientists are "playing God" and other religious issues have been ascribed to the technology from the beginning. Other ethical issues raised include the patenting of life, the use of intellectual property rights, the level of labeling on products, control of the food supply and the objectivity of the regulatory process. Although doubts have been raised, economically most studies have found growing GM crops to be beneficial to farmers.
Gene flow between GM crops and compatible plants, along with increased use of selective herbicides, can increase the risk of "superweeds" developing. Other environmental concerns involve potential impacts on non-target organisms, including soil microbes, and an increase in secondary and resistant insect pests. Many of the environmental impacts regarding GM crops may take many years to be understood are also evident in conventional agriculture practices. With the commercialisation of genetically modified fish there are concerns over what the environmental consequences will be if they escape.
There are three main concerns over the safety of genetically modified food: whether they may provoke an allergic reaction; whether the genes could transfer from the food into human cells; and whether the genes not approved for human consumption could outcross to other crops. There is a scientific consensus that currently available food derived from GM crops poses no greater risk to human health than conventional food, but that each GM food needs to be tested on a case-by-case basis before introduction. Nonetheless, members of the public are much less likely than scientists to perceive GM foods as safe.
The ProcessGenetic engineering is the insertion of a segment of DNA containing one or more genes from one organism into a chromosome of another organism. This process, when successful, allows the expression of the added gene in the host organism. The process involves using either a virus or bacterium nucleic acid as a vector of insertion, or else doing the job with a micropipette or by bio-ballistic DNA delivery with a �gene gun� (Nicholl, 1994; Ho, 1996). To be sure that the gene you are trying to insert is actually present, the added segment of DNA usually includes a �marker gene� which is most often a gene for antibiotic resistance. The organism is then grown in a culture containing the antibiotic. Only those individuals with the added segment of DNA will survive, since they are the only organisms that are resistant to the antibiotic. At least this is how desired genes are usually identified, with a marker for antibiotic resistance. So far, there have been about 50 different food crop approvals for genetically engineered varieties (U.S.FDA, 2000).
Once the desired genes are inserted into the selected organism, the new genetically engineered organism is reproduced to obtain a generation of individuals that possess the desired trait. These individuals in turn are raised and utilized with the desired gene actively functioning. Some examples are the S-adenosylmethionine hydrolase gene from a bacterium which was added to cantaloupe to control ripening, the Phosphinothricin acetyltransferase gene from another bacterium which confers Glufosinate (Roundup�- an herbicide) tolerance, and the potato that is insect resistant with the cryIIIA gene from Bacillus thuringiensis (Bt) sp. tenebrionis (another bacterium) (U.S.FDA, 2000).
There are many other GMOs that have been produced and are being used for crop production at this time. There are 50 examples of genetic engineering reported by the U.S.FDA (2000). These GMOs confer resistance to pesticides, more uniform ripening, resistance to insects and viruses and improved protein content of several food crops. So why are there so many protests to genetic engineering?
Any time the position of a gene is changed, there may be a change in the production of proteins. This may lead to unexpected results. The new protein produced may be intentional, as in the case of the production of protein by the Bt gene described below, or unintentional, as in the attempt to increase methionine levels in soybeans, the second case described below.
The Bt gene is a gene found in a bacterium and codes for the production of a protein (Bt) that is a natural insecticide. This gene has recently been engineered into corn, tomatoes, cotton and potatoes (U.S.FDA, 2000). This would mean that we could have plants with a built-in insecticide, and this insecticide would greatly reduce the use of harmful chemical insecticides in the environment. But very quickly three very disturbing problems seem to be arising. One, will insects develop a tolerance for this protein? This seems to have occurred in some trials of engineered cotton in Texas. Two, will the Bt gene �escape� into the wild, weedy relatives living in the area? If this happens, will they have an advantage over native plants in that the weeds will be more resistant to insects? (Feder, 1996; Beardsley, 1996a). And three, will the Bt toxin affect humans? It seems as if we are not entirely sure of what we are attempting.
In an experimental attempt to boost the methionine level in soybeans, a gene from Brazil nuts was introduced into a soybean variety intended for use as animal feed. But the introduction of a new gene may lead to the production of a new protein (Fig.1). In this case the new protein caused a �life-threatening allergic reaction in people�(Beardsley, 1996). The company quickly stopped the project (Beardsley, 1996; Feder, 1996; Leary, 1996). Here again we see an unexpected result from an attempt at genetic engineering.
This �life-threatening allergic reaction� was a determination made in the laboratory using blood serum from nine patients who were allergic to Brazil nuts (Leahy, 1996). All nine reacted to extracts of the Brazil nut. Eight of nine reacted to the genetically engineered soybean extract, but none reacted to the extract from regular, plain soybeans. Skin prick tests on three volunteers showed the same results. This was part of the normal pre-release process that genetic engineering companies are required to perform on their own by the FDA (Sudduth, 2000). This example of a potentially serious result is often quoted by opponents to genetic engineering, even now, five years after the fact. And it is frequently implied that people were put at serious risk, even though all of the allergic reaction procedures were done in the laboratory on blood serum and no one became ill.
Insertion of a desired gene requires not only a vector for insertion, usually a viral gene, but also a marker gene for antibiotic resistance. One other problem is that each gene inserted into another organism needs an activator gene. The host organism is very unlikely to furnish this activator, so one is usually provided with the inserted gene. Virus activator genes have evolved to overcome host cell indifference to an added gene. These virus genes are very powerful activators, and are normally what is used to activate an inserted gene (Steinbrecher, 1999). There are also some bacterial activators used. We do not know the long-term effects of using these microbial genes in genetic engineering. If they are passed to other organisms there may be problems that we cannot imagine at the present time.
- A. Normal Gene Position
Repressor Gene Activator Gene Structural Gene
- B. With Inserted Gene from Transgenic organism
Repressor Gene Activator Gene Inserted Genes Structural Gene
The position of the inserted genes may have an effect on the organism. If the insertion is in the middle of another gene, it will effectively block the expression of that gene. Using a gene gun or microbial transfer, we have no knowledge of exactly where genes may be inserted. We are basically �shooting in the dark� and hoping that we place a gene into the genetic makeup of a host cell in a location where it can be effectively expressed. This insertion may make a host structural gene inoperative or it may destroy an activator gene (Figure 1). Either way, it may change the genetic expression of the host in an unexpected fashion.
Blockage No expression or changed protein expressed
Finally, we can see that the insertion of one transgenic gene actually involves the insertion of at least four separate genes, i.e:
- 1. The insertion vector gene (usually a virus)
- 2. The marker gene (usually for antibiotic resistance)
- 3. The activator gene (usually a virus)
- 4. The transgenic structural gene
|In addition the position of the inserted set of genes has a great effect on gene expression and protein production. It becomes apparent that this process is far more complicated and imprecise than has been stated by proponents (Maryanski, 1995).|
The JustificationThe use of genetic engineering as a tool to improve crop plants for human use is an idea that should be irreproachable (Farnham et al, 1999; DellaPenna, 1999, Mazur, et al, 1999). The four major areas of research indicated above are certainly all worthy areas of endeavor. But perhaps the ultimate justification for genetic engineering is the specter of an entire world in famine. There are now six billion humans on this planet. Within the next fifty years we will be very close to nine billion people. If we do not discover and quickly use some effective form of population control, we will have to produce much more food than we are producing at the present time (Prakash, 1999). By the year 2025, we will need to raise cereal grain production eighty-five percent over the 1990 level if we are to keep pace with population growth (Serageldin, 1999).
Genetic engineering is one way by which we may be able to boost the production of food to needed levels. Food crops with built-in insecticides, such as the Bt toxin, should be easier, safer and cheaper to grow, and produce higher yields. Those crops that are tailored nutritionally should be able to eliminate some serious chronic deficiencies in diets in some parts of the world. Fruits and vegetables that ripen when needed should make it possible to get more produce to market at the optimum time, minimizing waste. Plants that are genetically engineered to produce some specific product may entirely change the economics of medicines and make some drugs much more available than at the present. GMOs may also be able to provide some effective method of birth control (Pollack, 2000; Farnham et al, 1999).
Political AspectsDespite all of the promise shown above, we are not making as much progress as we might be. Why? Because there has developed an enormous protest to the entire idea of genetic engineering. This protest does not seem to be abating, and has spread to many countries around the world. Those people protesting GMOs are very vocal and very well organized (see AmeriScan, 2000; Anon., 2000, Arnett, 2000; Genetic ID, 1999; Mothers for Natural Law, 1999, 1999a, 1999b, 2000; Natural Law, 2000; and others). Some of the protests seem frivolous, some seem legitimate and all of the protesters seem to show genuine concern. What are these people saying?
Nature of the ProtestOf all the protest materials which I have read, there seem to be several specific categories into which most of the protests to genetic engineering fall:
4. That GMOs will have an adverse effect on wild plants and animals.
- 1. That genetic engineering will produce a protein that will subtly cause allergic reactions in people.
- 2. That the Bt insecticide produced in plant tissue will poison people eating the plant.
- 3. That crops, especially fruits, produced using genetic engineering will be tasteless or will taste bad.
Some of these objections are valid, others seem not to be. Before we examine these objections in more detail, we should say something about how these protests are being carried out.
- 5. That genetically engineered crops will have an adverse effect on natural ecosystems.
- 6. That genetic engineering is unnatural and will produce GMOs that could never come from nature.
- 7. That the viral and bacterial vector and activator genes used may be recombined in the wild and form some deadly new pathogens.
- 8. That GMOs are an attempt by large corporations to obtain a monopoly on seed production and thus dominate the world.
- 9. That we don�t need genetic engineering and more food anyway, we simply need to develop more efficient means of food distribution.
- 10. That genetic engineering is evil.
Methods of ProtestThis protest seems to be the first that has utilized mankind�s new-found attachment - the internet. There are a large number of web sites devoted to the protest of genetic engineering (see AmeriScan, 2000; Anon., 2000, Arnett, 2000; Genetic ID, 1999; Mothers for Natural Law, 1999, 1999a, 1999b, 2000; Natural Law, 2000; and others). The use of the internet has made it possible for people to bombard their congressman/woman with complaints, and to do so repeatedly since it is easy to use a new name each time, and hard to trace communications using many e-mail addresses.
There are a large number of articles on genetic engineering found on the internet, many sound in their science and point of view. But there are also many articles that show little understanding of the biology involved in genetic engineering. See for example the two letters to the editor of the Washington Post (Dushay, 2000; Young, 2000). These letters are a reply to an article discussing genetic engineering of characteristics such as �hard work, courage, and creative imagination� . The author of the article (Michael Kinsley) seemingly did not understand the complex interrelationship between heredity and the environment.
Another tactic used by opponents of genetic engineering is that of overstating the evidence. For example, researchers in a laboratory at Cornell University fed Monarch butterfly caterpillars Bt toxin by dusting pollen from Bt corn on the leaves of milkweed, the sole food of Monarch caterpillars. Approximately 50% of the caterpillars died within four days and those left living did not appear to be healthy. These results were published in many articles (Center for Science and Media, 1999; Leahy, 2000; LeTourneau, 2000) and most of these articles seemed to imply that the natural populations of monarchs were in danger. In only one article (Center for Science and Media, 1999) was it made clear that this study was done in the laboratory and that the situation has not yet been examined in the wild. The results of this experiment were definitely overstated and generalized. We must now explore the question of the validity of protests against genetic engineering.
Validity of the ProtestOne of the most repeated criticisms of genetic engineering is that it is creating unnatural organisms that could not possibly occur in nature and that these organisms are only produced in the laboratory and could never be produced in nature (Genetic ID, 1999). However, there are GMOs produced naturally, as well as in the laboratory (Hilts, 1996).
There have been several incidents in the past several years of people becoming sick, and some actually dying, from hemorrhagic colitis. This disease is a severe form of diarrhea and is caused by the Escherichia coli bacterium, strain O 157: H7. But E. coli is common and normally present in large numbers in the intestinal tract of mammals. What caused this strain to become so virulent?
There is another bacterium named Shigella dysenteriae . This bacterium produces Shiga toxin which causes diarrhea. The gene for Shiga toxin has jumped from Shigella to E. coli. When present in the much more common E. coli the Shiga toxin gene causes the production of the Shiga toxin in large quantities. If undercooked meat, especially ground hamburg with its large internal surface area, is eaten the E.coli in the hamburg ends up in the intestine. If it is carrying the gene for Shiga toxin, hemorrhagic colitis will result (Hilts, 1996).
This seems to be a case of natural genetic engineering. But the consequences for man have been severe. Many people have been stricken with hemorrhagic colitis and a few have died. In the Jack-In-The-Box restaurant incident of 1993 four children died and many people were stricken. In July, 1996 the same strain of E. coli caused extensive food poisoning in Japan, with at least four deaths reported (Anon., 1996b). A later report sets the death toll at 100 and the number stricken at 8700. It was reported that there were 100 new cases per day (Anon, 1996c).
From the Shiga toxin results, we can see that the distinction between man-made GMOs and naturally occurring GMOs is rather meaningless. There is no support for the idea that man-made GMOs are inherently �bad� and natural GMOs are somehow �good� because they are natural.
At this point in time, we are facing a world population of six billion people. By 2050 estimates are that the population will be almost nine billion people (Prakash, 1999). GMO opponents say that increased and more efficient food transportation will solve the hunger problem. Most reputable scientists say that we must produce more food (Miller, 1990). To improve general levels of health, we must also increase plant phytonutrients, particularly micronutrients. These include organic phytonutrients such as vitamins and specific amino acids and inorganic phytonutrients such as calcium, iron and other minerals. These increases are possible through the manipulation of the secondary metabolisms of plants by the use of genetic engineering (Farnham et al, 1999; DellaPenna, 1999, Mazur, et al, 1999).
We must, by some method, raise food production soon if we are to feed everyone. Even today there are millions of people starving in our world. It is mainly but not entirely a question of distribution. At the present time, while our world population increases, our natural resources decline even further. We have less arable land to farm each year. Many acres per year are lost to erosion, urban and suburban sprawl, and shopping malls. And our soils become more polluted every year. By the year 2025, we will need to raise cereal grain production eighty-five percent over the 1990 level if we are to keep pace with population growth (Serageldin, 1999). The use of GMOs may be the solution to many of our food production problems (Prakash, 1999).
Today seventy four percent of the genetically engineered acreage is planted in the U.S. and ten percent in Canada. Argentina plants fifteen percent. The rest of the world plants only one percent. The five major GMO crops are soybean, maize (corn), cotton, rapeseed (canola oil) and potato (Serageldin, 1999). Both genetic engineering products and processes are patented. Many of the genes used in genetic engineering come from plants and animals found in third world countries. There is growing concern among these countries that they will have furnished much of the raw genetic materials, but will not be able to afford the products produced. (Moffat, 1999a; Overseas Devel. Inst., 1999).
Perhaps unfortunately, many large global conglomerates are rapidly buying up biotech and seed companies, as well as agribusinesses and agrochemical companies. The control of the agricultural seed and pesticide industry is rapidly falling into the hands of these large corporations. (Rifkin, 1998). This concentration of control is significant, with only ten companies controlling 37% of the global seed market, and only ten companies controlling 81% of the global agrochemical market. (Rifkin, 1998).
It is easier to genetically change plants and microbial organisms than it is to alter the genetic composition of mammals (Somerville and Somerville, 1999). Many genes for genetic engineering have come from contributors of blood samples and seeds from third world countries. These genes have then been patented and commercialized so that third world farmers cannot afford to use the genetic products produced. (Shiva, 1997). The discovery and use of these genomes is called �bioprospecting� (or �biopiracy� by its detractors) (Snell, 1995).
This control and patenting of genomes makes it almost impossible to make knowledge freely available to third world farmers and research institutions. But normally third world (Southern) countries are not competing in targeted Northern markets. This makes it possible for information to be shared without violating patents. Monsanto and other companies are currently sharing information with third world countries (Serageldin, 1999). Thus there may be some hope of increasing third world crop quantity and quality without depriving Monsanto, Dupont, Novartis, Upjohn, Eli Lilly, Rohm and Haas, Dow Chemical, Amgen, Organogenesis, Genzyme, Calgene, Mycogen, Myriad, Bayer, Rhone-Polenc and others of their share of the genetic engineering market (Rifkin, 2000, Pure Food Campaign, 1999).
But even with organisms engineered from local species in the U.S. there are ethical questions raised. A plant has recently been genetically engineered to take up mercury from the environment (anon., 1996a). The plant will absorb very large quantities of mercury from the soil as it grows. The plant may then be harvested and the mercury is removed from the environment along with the plant. Plants have also been engineered to pick up excess amounts of copper, cadmium and aluminum in the soil (Moffat, 1999). But this has only been accomplished in the laboratory and we do not know the effects of releasing these altered genomes into the environment. The effect might be one entirely unexpected. For example, what if the plant also takes up abnormally large quantities of an essential mineral? What would happen to the soil? Or what would happen if the gene for mercury accumulation �jumped� (horizontally moved) to an important crop plant? And how and where do you dispose of the plant material loaded with mercury? It is these kinds of uncertainty that seems to be driving the protest movement.
In another carefully controlled experiment, Rapeseed plants were genetically engineered with a gene for resistance to the herbicide Roundup�. These plants were then allowed to grow with a native related plant, a weed called Wild Mustard. The result was that the genetic package making Rapeseed plants tolerant to the herbicide Roundup� was horizontally moved to this related wild species, Wild Mustard, and the weed ended up with the genes for resistance to the herbicide. (Beardsley, 1996a). Horizontal movement is the term usually employed when talking about the transfer of genetic material from one species to another in the wild (the terms �escaped genes� and genes that �jumped� are also often used). In this case the experiment was closely controlled, all the plants were destroyed and there was no harm done (Beardsley, 1996a). However, this experiment does show how easily genes can escape from genetically engineered crops into the surrounding natural environment. Much more serious problems may develop if some of the viral and bacterial genes are horizontally moved in the soil to other microorganisms. There is the real potential for the development of some very pathogenic microorganisms. (Ho and Tappeser, 1997; Beardsley, 1996a). And this is another large concern of protesters.
The Bt gene is a gene naturally found in a bacterium and codes for the production of a protein that is a natural insecticide. This gene has recently been engineered into corn, cotton, tomatoes, rapeseed and potatoes (U.S.FDA, 2000). There are great fears that this natural insecticide will somehow poison humans, and that crop pests will become resistant to it. There is some indication that this developing resistance may already have started (Feder, 1996). But one aspect that few people seem to be taking into account is the action of this insecticide.
There are two excellent articles on the biology of the Bt toxin and the possible horizontal movement of the Bt gene in nature (Tappeser, 1997; Tappeser et al, 1998). The Bt gene is naturally present in the bacterium Bacillus thuringiensis and codes for the production of a protein. This protein is found as a crystal in the bacterial spores in parasporal inclusion bodies. Normally the larva of an insect will take in the bacterial spores when it is ingesting the leaf tissue of a host plant. When the spores reach the intestine of the insect larva, the parasporal inclusion bodies are released.
The alkaline pH of the insect intestine causes the released Bt crystalline protein to become soluble. This protoxin is split into two smaller toxin proteins by an insect protease enzyme present in the gut. These smaller proteins penetrate the peritrophic membrane of the intestine and reach specific receptors on the cells of the intestinal wall. This results in the destruction of ion gradients and in the formation of pores which allow the vegetative Bt cells which have germinated from the spores to pass into the haemolymph, causing an intoxication of the insect larva. The larva becomes anesthetized and dies from exposure, dehydration and starvation. (Tappeser, 1997).
With genetic engineering the Bt gene has been added into the cells of some crop plants. When an insect larva chews on a leaf of one of these crops, the gene has already produced the Bt protein in the smaller, cleaved toxin form, and this has the same toxic effects on the intestines of the larva. The larva is effectively killed. In this case, there seems to be no need to consider the protoxin. The toxins are present in the cells and act directly on the insect. (Tappeser, 1997).
It is hard to imagine these toxins having an effect on the human system. First, much of our food is cooked, which would denature these proteins. Second, the intensely acidic pH and protease enzymes of our stomachs would also denature and hydrolyze these proteins. It seems almost impossible that these toxic proteins would have any effect at all on humans. And to date there have been no reports of such effects.
As a result of genetic engineering there may be changes in the nature or amounts of the proteins produced in the transgenic plant or in the amounts or kinds of toxicants present. These changes are called pleiotropic effects. Many of the effects may be toxic or allergenic. The U.S FDA�s own internal memoranda show that within the FDA many scientists have had misgivings about allowing GMOs to be released for use without thorough testing for toxicity and allergenicity (Mothers for Natural Law, 1999a). These internal memoranda became public documents as the result of a lawsuit brought against the FDA to try to force the government to use some system of independent testing of GMOs before they are released (Coale, 2000).
Who is responsible for guaranteeing the safety of GMOs? The Bt gene and toxin seem to be guaranteed by no one. It is not a food additive so the FDA does not test it. It is an insecticide and therefore the FDA is prohibited from dealing with it. The Environmental Protection Agency (EPA) deals with pesticides. Except Bt is in a food, so the EPA tests only the isolated toxin in the laboratory, not as it is in the foods (Lovins, 1999). The United States Department of Agriculture (USDA) only concerns itself with additives to meat, fish and poultry. Bt toxin is there, an orphaned toxin without a regulating agency (Pollan, 1998). This situation is so frustrating to those concerned that there is a lawsuit against the FDA for failing to test GMOs (Coale, 2000).
One of the plant crops most used by the food industry in North America at the present time is the soybean. It is a source of proteins, oils and emulsifiers and is a basic ingredient in a very large number of processed foods. The soybean has been genetically engineered to change the composition of the oils produced, and to be tolerant of glyphosate (Roundup� herbicide) by increasing the concentration of the enzyme that controls aromatic amino acid biosynthesis. This biosynthetic change has greatly increased the isoflavonoids (phytoestrogens) present in soybean tissue. Using Roundup� on soybeans seems to further increase the levels of phytoestrogens. These act like regular mammalian estrogen hormones and effect sexual differentiation, blood clotting, calcium metabolism, cancerous tissue changes and immune functions. High doses of phytoestrogens, particularly in infants (from infant soy formulas), may cause serious health problems (Lappe and Bailey, 1997).
There are also a number of legal issues involved with genetic engineering. Who owns a gene? If you genetically engineer a gene into a host plant, you can patent the resulting transgenic plant. So genes are patentable and in a sense if you patent a gene it is yours. But if you sell your patented genes in plant seeds, what happens to them? A farmer will plant your seeds and raise your patented plants. Who owns the seeds from these plants? Many farmers, most in third world countries, save seeds from their crops each year to plant the next year. But these saved seeds are now patented! This forces the farmer to buy new seeds each year, and there is often an accompanying enforceable contract that says the farmer will buy pesticides only from the seed vendor! The legal issues over ownership of patented genes and seeds is still in flux. But it seems that the small farmer, who can least afford it, is stuck in a very expensive system (Bereano, 1995, 1995a).
Other legal issues concern the rights of third world countries to benefit from genetic engineering (Overseas Devel. Inst., 1999). If governments set too stringent standards for releasing GMOs into the market, the third world countries and the smaller producers will be economically shut out of this market (Huttner, 1999). And it is these smaller producers and countries who might benefit most from genetic engineering technology.
How is the rest of the world reacting to genetic engineering? For the most part genetic engineering of food crops is not being accepted. In Europe there is an active and vigorous opposition to GMOs (Gaskell et al, 1999; Daley, 2000). This opposition has spread to most of the food-importing countries of the world (Genetic ID, 1999, 1999a). The European Union has developed guidelines for GMOs (European Union, 1997) and the U.K. has revised and expanded guidelines for experimenting with GMOs (Health and Safety Exec. - U.K., 1998). There are serious environmental concerns in the U.K. which are now being addressed (NERC, 1998). The argument between the United States and the European Union over labeling of GMOs has not been resolved (Lyddon, 1999, 1999a). And yet, even with all of this global opposition to genetically engineered food crops, there has been hardly a decline in production of GMOs in the United States (Barboza, 2000).
There are a number of ethical issues involved in the genetic engineering controversy. Who has the right to the products of genetic engineering? Do large, transnational companies have the right to prohibit third world countries from using indigenous plants because their genes have been patented? (Ho, 1996). To what extent are we upsetting ecosystem balance using genes that may be moving horizontally though the ecosystem? (Fong, 2000; Rifkin, 1998). The danger of genetic engineering to the biosphere has been compared to the use of nuclear weapons and atomic energy. Horizontal movement may be the next Chernobyl! (Mann, 1999). We simply do not know the consequences of this large uncontrolled genetic experiment we have started. In the near future we may suffer massive genetic pollution and loss of genetic diversity, but we are presently taking no steps to prevent the disaster. (Rifkin, 1998).
We as a society have experienced events in our recent past that are at least perhaps partly comparable to genetic engineering - atomic energy and DDT. Each of these new technologies initially was promoted enthusiastically as a cure-all for mankind but was later found to be encumbered with hidden risks. Will genetic engineering have a similar history? (Epstein, 2000). We are proceeding rapidly with this new technology, but we are not being at all cautious about the possible long-term effects of genetic engineering. This may be in part because of the continued movement of high-level officials from government to industry to government (Epstein, 2000).
There is a rather large number of upper-level government officials who have taken executive positions with Monsanto, including an ex-cabinet secretary (Mickey Kantor, Secretary of Commerce) and an assistant to the President (Marcia Hale). And a number of Monsanto executives have taken upper-level management positions in the U.S. government. One Genentech executive (David Beier) has become an advisor to Vice-President Gore�s presidential campaign. The advantage seems to be entirely on the side of the large transnational companies. This revolving-door employment must have an effect on the policies of the federal government on genetic engineering (Epstein, 2000). Most opponents of genetic engineering say that the U.S. government is trying to force genetic engineering onto the rest of the world. (AmeriScan, 2000).
The three basic ethical issues involved in genetic engineering seem to be: 1) Does anyone have the right to patent genes? How can we assure everyone of equal access to genetic materials and the resulting products? Cost must be universally low and reasonable. Who will monitor this? 2) Genetic materials and experiments must be kept under tight controls and carefully tested . The U.S. government and agrochemical companies seem to be pursuing a policy that greatly benefits the genetic engineering industry and ignores legitimate concerns about safety. There seems to be no regulatory agency that is responsible for GMO safety. 3) No one seems to be addressing the issue of long-term environmental risk. What might happen to ecosystems if pathogenic genes undergo horizontal transfer? Might we be subjected to an eco-disaster? Why have we neglected testing for long-term effects?
ConclusionsSome of the opposition to GMOs seems almost irrational(Fong, 2000). Two Mothers for Natural Law web articles (1999 and 2000) assume that there is something to be avoided in genetically engineered foods. They furnish a list of food products to avoid, and a source for testing DNA of food products for genetic engineering. There is no discussion or justification for what they are saying. The assumption seems to be that if it is a GMO it is bad. There may well be some problems with GMOs, such as allergic reactions, changed flavors and horizontal movement of genes, but these need to be investigated in a rational manner, not with blanket condemnations and ignorance.
It is probably a positive thing that protesters have called attention to the phenomenon of genetic engineering and have insisted that the government be more active in the testing and licensing of these products. At the same time, there seems to be much misinformation and some hysteria about the subject of genetic engineering. There have been all kinds of dire predictions about GMOs. But genetic engineering has been singularly free of tragic consequences to date. The one exception seems to be the production of tryptophan by a Japanese company. Eleven people died from consuming tryptophan that was improperly genetically engineered and purified. However, we may conclude that the general short-term effects of genetic engineering on humanity is positive.
However, there seems to be no research being done on the long-term effects of genetic engineering. There are several basic questions unanswered:
Finally, from all I have read, I have concluded that genetic engineering can be of great benefit to humanity. But at the same time, I deplore the haste with which the biotechnology industry has pursued the production of GMOs and profit. The lack of research on possible long-term effects of genetic engineering is appalling.
- 1. Will people over time develop allergic reactions to the transgenic proteins produced from genetic engineering?
- 2. Will the horizontal movement of genetic materials have a negative impact on ecosystems?
- 3. Will some virulent new pathogen develop from the transfer and transformation of microbial DNA made available by genetic engineering?
- 4. Will humans be able to make the correct ethical choices so that all of humanity may share in the potential benefits of genetic engineering?
Notes to Teachers on the Laboratory Exercises:There are a number of points that need to be made to the teacher:
1. Roundup� is an herbicide and a poison. It has been implicated in non-Hodgkins lymphoma. It is easy and safe to apply, but you may want to do it yourself. A light spray on the leaves is all that is needed. Do it when there is no breeze!
2. Organic foods, obtainable in a health food store, are not genetically engineered. This is your source of soybean seeds, corn meal and tomatoes. The genetically engineered seeds may be purchased at an agricultural seed company, such as Hartz or Asgrow or Agway. Genetically engineered corn meal and tomatoes come from
the supermarket. 3. I do not know if you will have a suitable oven available. I have one I can use in the teacher�s room. Maybe you can use one in the cafeteria kitchen?
4. If you simply give the students two samples, and do not tell them which is which, you may obtain more unbiased results.
Roundup� Ready Soybeans
There is a very effective herbicide on the market called Roundup�. This poison is manufactured by Monsanto, who also sells a genetically engineered soybean called Roundup� Ready. This soybean has been engineered with a gene from the bacterium Agrobacterium that makes the soybean plant tolerant to the herbicide Roundup�. Thus one can plant these soybeans, wait until they are growing and six inches tall, and then spray the entire field with Roundup�. All of the weeds will die, leaving only the Roundup� Ready soybeans. We can demonstrate this rather simple example of genetic engineering in the laboratory.
The procedure is as follows:
1. Work as teams of two. Each team needs to obtain from the teacher the following supplies and equipment.
2. Label the cups on the side - use RR and PL. Include your initials. Punch a hole in the bottom of each cup with a pencil (allows excess water to drain out).
- a. Two styrofoam or paper cups filled with soil.
- b. Six soybean seed, three of each type - Roundup� Ready and plain.
- c. Two popsicle sticks to use as markers and probes.
3. Plant the soybean seeds about one inch deep in the soil. Place the three seeds of one type in one cup and the three seeds of the other type in the other cup.
4. Water the soil in both cups.
5. Place the cups in a window with plenty of sunlight. Water the cups every two or three days.
6. Keep a record of plant growth for each of the six plants.
7. When the plants are about 6 inches tall, spray each set of plants with Roundup�. Remember - THIS IS A POISON - it kills plants and has been found to cause cancer in laboratory mice. USE WITH EXTREME CAUTION (Your teacher may wish to do the spraying of the Roundup� herbicide!).
8. Continue to water the plants and observe what happens over the next two weeks. What was the effect of Roundup� on each type of soybean?
9. Write a laboratory report on your observations, explaining what happened and why.
Normal and Genetically Engineered Corn
There may be a noticeable difference between genetically engineered corn and plain corn. There might be a difference in taste. How could we discover if this is true? By making some simple corn dish such as corn bread. Most of the cornmeal available in supermarkets contains at least 50% genetically engineered corn. Corn meal purchased as �organically grown� and certified, contains no genetically engineered corn. The difference is quite easily shown in the laboratory. The procedure is as follows:
1. Work as teams of three. Each team needs to obtain from the teacher the following supplies and equipment.
2. Make up two batches of corn bread mix, using the following proportions:
- a. 1 Cup of regular corn meal
- b. 1 Cup of organic corn meal
- c. 1 Cup of sugar
- d. 11/2 Cups of biscuit mix.
- e. 2 aluminum cake tins
3. Place the two tins in an oven and bake at 350�F for about twenty minutes, until a knife blade inserted in the mix comes out clean.
- a. 1 Cup corn meal - (regular for one, organic for the other)
- b. 1/2 Cup sugar
- c. 3/4 Cup biscuit mix
- d. 1 Cup water.
- Mix all of the ingredients together in two cake tins and mark the tins by bending the rims.
4. Taste each corn bread. Can you detect any difference in taste? Is there any way to determine if any taste difference can be attributed to genetic engineering?
5. Write a report on this laboratory. Include your impressions and the vote of the entire class. Why do you think you obtained the results that you did?
Storage Life of Normal and Genetically Engineered Tomatoes
One of the recently introduced genetically engineered products is tomatoes that have a longer shelf life. Students can compare very easily the shelf life of genetically engineered tomatoes and organic tomatoes. Simply buy some of each and see how long they last in the classroom on the window sill. The students might also wish to periodically taste them, to see if there is any difference in taste.