Tuesday, January 22, 2008

Confocal microscopy

Confocal microscopy

Confocal microscopy is an optical imaging technique used to increase micrograph contrast and/or to reconstruct three-dimensional images by using a spatial pinhole to eliminate out-of-focus light or flare in specimens that are thicker than the focal plane. This technique has been gaining popularity in the scientific and industrial communities. Typical applications include life sciences and semiconductor inspection.


Basic concept

The principle of confocal imaging was patented by Marvin Minsky in 1957. In a conventional (i.e., wide-field) fluorescence microscope, the entire specimen is flooded in light from a light source. Due to the conservation of light intensity transportation, all parts of the specimen throughout the optical path will be excited and the fluorescence detected by a photodetector or a camera. In contrast, a confocal microscope uses point illumination and a pinhole in an optically conjugate plane in front of the detector to eliminate out-of-focus information. Only the light within the focal plane can be detected, so the image quality is much better than that of wide-field images. As only one point is illuminated at a time in confocal microscopy, 2D or 3D imaging requires scanning over a regular raster (i.e. a rectangular pattern of parallel scanning lines) in the specimen. The thickness of the focal plane is defined mostly by the square of the numerical aperture of the objective lens, and also by the optical properties of the specimen and the ambient index of refraction.

Types

Three types of confocal microscopes are commercially available: Confocal laser scanning microscopes, spinning-disk (Nipkow disk) confocal microscopes and Programmable Array Microscopes (PAM). Yields better image quality but the imaging frame rate is very slow (less than 3 frames/second); spinning-disk confocal microscopes can achieve video rate imaging—a desirable feature for dynamic observations such as live cell imaging.

Southern, Northern, and Western Blots

Southern blotting

The Southern blot (named for its inventor) uses gel electrophoresis together with hybridization probes to characterize DNA restriction fragments. Genomic DNA or DNA from a specific source, such as a lambda phage or cosmid clone, is digested, usually to completion, with a restriction endonuclease (or sometimes with two or more restriction endonucleases). Electrophoresis is then used to separate the fragments by size. The fragments are then blotted from the electrophoretic gel onto a sheet of nitrocellulose or similar support material, and fixed onto it by heating or other treatments. The attached DNA fragments are denatured to separate the strands and annealed with a radioactive probe that is single stranded or also denatured. The nitrocellulose sheet is then washed, removing all unbound probe, and leaving radioactivity only where the probe has hybridized to the original DNA bound to the membrane. A sheet of X-ray film is then laid over the nitrocellulose for a time period long enough for the radioactivity to "expose" the film. When the film is developed, dark bands appear wherever there were DNA fragments capable of hybridizing with the radioactive probe. Size standards run on the same electrophoretic gel allow the sizes of the fragments identified by the probe to be determined.

Interpreting Southern blots

Matching the positions of the radioactive spots with those of the size standards identifies the sizes of the digestion fragments that hybridize with the probe. For example, a cDNA probe for a gene that contains two internal cut sites for the restriction enzyme will generate three fragments (which will usually have enough size difference so that all three can be detected). More complex patterns generated by repetitive sequences form the basis for DNA fingerprinting, which will be discussed in a future lecture. Note that it is not necessary for the entire length of the probe to hybridize with the entire length of the DNA fragment. A relatively short complementary sequence (less than 100 bp) is usually enough to obtain a strong hybridization signal. In addition, modification of the annealing conditions can alter the stringency of hybridization (the precision of base-pair matching needed for hybridization). By using reduced stringency, it is often possible to obtain hybridization between slightly mismatched sequences, such as the coding sequences for the same protein from different species.

Alternative sources of multiple bands

If a probe hybridizes with only a single band, one can conclude that only one size class of fragments contains the probe sequence. However, if two or more bands hybridize, two very different interpretations are possible: 1) that there is a restriction endonuclease cut site within the sequence that hybridizes to the probe, causing the hybridizing sequence to be cleaved into two different restriction fragments that can both hybridize with parts of the probe; or 2) that more than one copy of the target sequence was present in the original DNA sample, with each copy emerging in a different sized restriction fragment. It is often desirable to use a relatively small probe to minimize the chance of a single target sequence being cleaved into two halves during digestion of the original sample. On the other hand, there are times when a much larger probe is more effective, for example to be certain that all of the genomic restriction fragments that contain any part of a protein coding sequence have been identified.

Dot blotting

In cases where the goal is simply to test for the presence of a specific sequence, such as whether or not an attempt to clone a particular gene has been successful, size separation can be bypassed altogether and a bit of DNA from each putative clone can be transferred to a nitrocellulose membrane as a "dot", followed by hybridization to a probe and autoradiography. Only those dots that contain the desired sequence will hybridize and become labeled. This procedure is similar to the colony and plaque hybridization techniques discussed in previous lectures on gene cloning.

Northern blotting

In a Northern blot (named because it is the opposite of a Southern blot), RNA molecules of varying lengths (often naturally occurring mRNAs) are separated by size and blotted onto nitrocellulose. A DNA probe (often a cDNA) is then used to identify bands that contain particular sequences. Northern blots are particularly useful for determining the conditions under which specific genes are being expressed, including which tissues in a complex organism express which of its genes at the mRNA level.

Western blotting

In a Western blot, proteins are separated by electrophoresis and blotted onto an appropriate support matrix. The matrix is then exposed to an antibody to the desired protein and all unbound antibody is washed off. The bands (or spots in a dot blot) where the antibody has bound are then detected by various means, such as binding of a second antibody that is radioactively labeled and specific for the first antibody

Thursday, January 17, 2008

Genetically modified food

Genetically modified food

Kenyans examining insect-resistant transgenic BT corn.

Genetically modified (GM) foods are foodstuffs produced from genetically modified organisms (GMO) that have had their genome altered through genetic engineering. GM Foods have been available since the 1990s. The most common modified foods are derived from plants: soybean, corn, canola and cotton seed oil and wheat.

The process of producing a GMO used for GM Foods may involve taking DNA from one organism, modifying it in a laboratory, and then inserting it into the target organism's genome to produce new and useful traits or phenotypes. Such GMOs are generally referred to as transgenics. Other methods of producing a GMO include increasing or decreasing the number of copies of a gene already present in the target organism, silencing or removing a particular gene or modifying the position of a gene within the genome.Controversies surrounding GM foods and crops commonly focus on human and environmental safety, labeling and consumer choice, intellectual property rights, ethics, food security, poverty reduction, and environmental conservation. See also: GM food controversy

The first commercially grown genetically modified whole food crop was the Flavr Savr tomato, which was made more resistant to rotting by Californian Company Calgene. Calgene was allowed to release the tomatoes into the market in 1994 without any special labeling. It was welcomed by consumers that purchased the fruit at two to five times the price of regular tomatoes. However, production problems and competition from a conventionally bred, longer shelf-life variety prevented the product from becoming profitable. A variant of the Flavr Savr was used by Zeneca to produce tomato paste which was sold in Europe during the summer of 1996. The labeling and pricing were designed as a marketing experiment, which proved, at the time, that European consumers would accept genetically engineered foods.

The attitude toward GM foods would be drastically changed after outbreaks of Mad Cow Disease weakened consumer trust in government regulators, and protesters rallied against the introduction of Monsanto's "Roundup-Ready" soybeans. The next GM crops included insect-protected cotton and herbicide-tolerant soybeans both of which were commercially released in 1996. GM crops have been widely adopted in the United States. They have also been extensively planted in several other countries (Argentina, Brazil, South Africa, India, and China) where agriculture is a major part of the total economy. Other GM crops include insect-protected maize and herbicide-tolerant maize, cotton, and rapeseed varieties.

Abundance of GM crops

Between 1995 and 2005, the total surface area of land cultivated with GMOs had increased by a factor of 50, from 17,000 km² (4.2 million acres) to 900,000 km² (222 million acres), of which 55 percent were in the United States.

Although most GM crops are grown in North America, in recent years there has been rapid growth in the area sown in developing countries. For instance in 2005 the largest increase in crop area planted to GM crops (soybeans) were in Brazil (94,000 km² in 2005 versus 50,000 km² in 2004.) There has also been rapid and continuing expansion of GM cotton varieties in India since 2002. (Cotton is a major source of vegetable cooking oil and animal feed.) It is predicted that in 2006/7 32,000 km² of GM cotton will be harvested in India (up more than 100 percent from the previous season). Indian national average cotton yields of GM cotton were seven times lower in 2002, because the parental cotton plant used in the genetic engineered was not well suited to the climate of India and failed. The publicity given to transgenic trait Bt insect resistance has encouraged the adoption of better performing hybrid cotton varieties, and the Bt trait has substantially reduced losses to insect predation. Economic and environmental benefits of GM cotton in India to the individual farmer have been documented.

In 2003, countries that grew 99 percent of the global transgenic crops were the United States (63 percent), Argentina (21 percent), Canada (6 percent), Brazil (4 percent), China (4 percent), and South Africa (1 percent) The Grocery Manufacturers of America estimate that 75 percent of all processed foods in the U.S. contain a GM ingredient[. In particular, BT corn, which produces the pesticide within the plant itself is widely grown, as are soybeans genetically designed to tolerate glyphosate herbicides. These constitute "input-traits" are aimed to financially benefit the producers, have indirect environmental benefits and marginal cost benefits to consumers.
In the US, by 2006 89% of the planted area of soybeans, 83 percent of cotton, and 61 percent maize was genetically modified varieties. Genetically modified soybeans carried herbicide tolerant traits only, but maize and cotton carried both herbicide tolerance and insect protection traits (the latter largely the Bacillus thuringiensus BT insecticidal protein). In the period 2002 to 2006, there were significant increases in the area planted to BT protected cotton and maize, and herbicide tolerant maize also increased in sown area.

Future developments

Future envisaged applications of GMOs are diverse and include drugs in food, bananas that produce human vaccines against infectious diseases such as Hepatitis B, metabolically engineered fish that mature more quickly, fruit and nut trees that yield years earlier, and plants that produce new plastics with unique properties. While their practicality or efficacy in commercial production has yet to be fully tested, the next decade may see exponential increases in GM product development as researchers gain increasing access to genomic resources that are applicable to organisms beyond the scope of individual projects. Safety testing of these products will also at the same time be necessary to ensure that the perceived benefits will indeed outweigh the perceived and hidden costs of development. Plant scientists, backed by results of modern comprehensive profiling of crop composition, point out that crops modified using GM techniques are less likely to have unintended changes than are conventionally bred crops.

Monsanto Canada Inc. v. Schmeiser

Enforcement of patents on genetically modified plants is often contentious, especially because of the occurrence of Gene flow. In 1998, 95-98 percent of about 10 km² planted with canola by Canadian farmer Percy Schmeiser were found to contain Monsanto's patented Roundup Ready gene although Schmeiser had never purchased seed from Monsanto.]The initial source of the plants was undetermined, and could have been through either gene flow or intentional theft. However, the overwhelming predominance of the trait implied that Schmeiser must have intentionally selected for it. The court determined that Schmeiser had saved seed from areas on and adjacent to his property where Roundup had been sprayed, such as ditches and near power poles.

Although unable to prove direct theft, Monsanto sued Schmeiser for piracy since he knowingly grew Roundup Ready plants without paying royalties (Ibid). The case made it to the Canadian Supreme Court, which in 2004 ruled 5 to 4 in Monsanto’s favor. The dissenting judges focused primarily on the fact that Monsanto's patents covered only the gene itself and glyphosate resistant cells, and failed to cover transgenic plants in their entirety.

In response to criticism, Monsanto Canada's director of public affairs stated that "It is not, nor has it ever been Monsanto Canada's policy to enforce its patent on Roundup Ready crops when they are present on a farmer's field by accident...Only when there has been a knowing and deliberate violation of its patent rights will Monsanto act."] Currently Percy Schmeiser spends a large amount of his time traveling and speaking about how Monsanto ruined his career as a farmer. He also talks about the possible harms of genetically modification and why others in addition to him should be protesting it.

Coexistence and traceability

In many countries, and especially in the European Union, consumers demand the choice between foods that have been genetically modified, conventional or organic origins. This requires a labelling system as well as the reliable separation of GM and non-GM organisms at production level and throughout the whole processing chain.

Research has demonstrated, that coexistence of GM crops can be realized by several agricultural measures, such as isolation distances or biological containment strategies.

For traceability, the OECD has introduced a "unique identifier" which is given to any GMO when it is approved. This unique identifier must be forwarded at every stage of processing.

Many countries have established labelling regulations and guidelines on coexistence and traceability. Research projects such as Co-Extra, SIGMEA and Tran container are aimed at investigating improved methods for ensuring coexistence and providing stakeholders the tools required for the implementation of coexistence and traceability.

Policy around the world

Some argue that there is more than enough food in the world and that the hunger crisis is caused by problems in food distribution and politics, not production, so people should not be offered food that may carry some degree of risk.

Others oppose genetic engineering on the grounds that genetic modifications might have unforeseen consequences, both in the initially modified organisms and their environments. For example, certain strains of maize have been developed that are toxic to plant eating insects (see BT corn). It has been alleged those strains cross-pollinated with other varieties of wild and domestic maize and passed on these genes with a putative impact on Maize biodiversity.[18] Subsequent to the publication of these results, several scientists pointed out that the conclusions were based on experiments with design flaws. It is well known that the results from the Polymerase Chain Reaction method of analyzing DNA can often be confounded by sample contamination and experimental artifacts. Appropriate controls can be included in experiments to eliminate these as a possible explanation of the results - however these controls were not included in the methods used by Quist and Chapela. After this criticism Nature, the scientific journal where this data was originally published concluded that "the evidence available is not sufficient to justify the publication of the original paper".] More recent attempts to replicate the original studies have concluded that genetically modified corn is absent from southern Mexico in 2003 and 2004. Also in dispute is the impact on biodiversity of the introgression of transgenes into wild populations .Unless a transgenic offers a massive selective advantage in a wild population, a transgene that enters such a population will be maintained at a low gene frequency. In such situations it can be argued that such an introgression actually increases biodiversity rather than lowers it.

Activists opposed to genetic engineering say that with current recombinant technology there is no way to ensure that genetically modified organisms will remain under control, and the use of this technology outside secure laboratory environments carries potentially unacceptable risks to both farmed and wild ecosystems.

Potential impact on biodiversity may occur if herbicide-tolerant crops are sprayed with herbicide to the extent that no wild plants ('weeds') are able to survive. Plants toxic to insects may mean insect-free crops. This could result in declines in other wildlife (e.g. birds) which feed on weed seeds and/or insects for food resources. The recent (2003) farm scale studies in the UK found this to be the case with GM sugar beet and GM rapeseed, but not with GM maize (though in the last instance, the non-GM comparison maize crop had also been treated with environmentally-damaging pesticides subsequently (2004) withdrawn from use in the EU).
Although some scientists have claimed that selective breeding is a form of genetic engineering, (e.g., maize was modified from teosinte, dogs have evolved with human intervention over the course of tens of thousands of years from wolves), others assert that modern transgenesis-based genetic engineering is capable of delivering changes faster than, and sometimes of different types from, traditional breeding methods.

Proponents of current genetic techniques as applied to food plants cite the benefits that the technology can have, for example, in the harsh agricultural conditions of Africa. They say that with modifications, existing crops would be able to thrive under the relatively hostile conditions providing much needed food to their people. Proponents also cite golden rice and golden rice 2, genetically engineered rice varieties (still under development) that contain elevated vitamin A levels. There is hope that this rice may alleviate vitamin A deficiency that contributes to the death of millions and permanent blindness of 500,000 annually.

Proponents say that genetically-engineered crops are not significantly different from those modified by nature or humans in the past, and are as safe as or even safer than such methods. There is gene transfer between unicellular eukaryotes and prokaryotes. There have been no known genetic catastrophes as a result of this. They argue that animal husbandry and crop breeding are also forms of genetic engineering that use artificial selection instead of modern genetic modification techniques. It is politics, they argue, not economics or science, that causes their work to be closely investigated, and for different standards to apply to it than those applied to other forms of agricultural technology.

Proponents also note that species or general barriers have been crossed in nature in the past. An oft-cited example is today's modern red wheat variety, which is the result of two natural crossings made long ago. It is made up of three groups of seven chromosomes. Each of those three groups came from a different wild wheat grass. First, a cross between two of the grasses occurred, creating the durum wheat’s, which were the commercial grains of the first civilizations up through the Roman Republic. Then a cross occurred between that 14-chromosome durum wheat and another wild grass to create what became modern red wheat at the time of the Roman Empire.

Economic and political effects

· Many opponents of current genetic engineering believe the increasing use of GM in major crops has caused a power shift in agriculture towards Biotechnology companies, which are gaining more control over the production chain of crops and food, and over the farmers that use their products, as well.
· Many proponents of some current genetic engineering techniques believe it will lower pesticide usage and has brought higher yields and profitability to many farmers, including those in developing nations. A few genetic engineering licenses allow farmers in less economically developed countries to save seeds for next year's planting.
· In August 2002, Zambia cut off the flow of Genetically Modified Food (mostly maize) from UN's World Food Programme. This left a famine-stricken population without food aid.
· In December 2005 the Zambian government changed its mind in the face of further famine and allowed the importation of GM maize. [9]. However, the Zambian Minister for Agriculture Mundia Sikatana has insisted that the ban on genetically modified maize remains, saying "We do not want GM (genetically modified) foods and our hope is that all of us can continue to produce non-GM foods
· In April 2004 Hugo Chavez announced a total ban on genetically modified seeds in Venezuela.
· In January 2005, the Hungarian government announced a ban on importing and planting of genetic modified maize seeds, although these were agreed authorized by the EU.
· On August 18, 2006, American exports of rice to Europe were interrupted when much of the U.S. crop was confirmed to be contaminated with unapproved engineered genes, possibly due to accidental cross-pollination with conventional crops. The U.S. government has since declared the rice safe for human consumption, and exports to some countries have since resumed.

Introduction to Biotechnology

Introduction to Biotechnology

The term "biotechnology" refers to the use of living organisms or their products to modify human health and the human environment.

Biotechnology combines disciplines like genetics, molecular biology, biochemistry, embryology and cell biology, which are in turn linked to practical disciplines like chemical engineering, information technology, and robotics.

History of Biotechnology

The most practical use of biotechnology, which is still present today, is the cultivation of plants to produce food suitable to humans. Agriculture has been theorized to have become the dominant way of producing food since the Neolithic Revolution. Through early biotechnology farmers were able to select the best suited and highest-yield crops to produce enough food to support a growing population. Other uses of biotechnology were required as crops and fields became increasingly large and difficult to maintain. Specific organisms and organism byproducts were used to fertilize, restore nitrogen, and control pests.

Cultures such as those in Mesopotamia, Egypt, and Iran developed the process of brewing beer. It is still done by the same basic method.

Later other cultures produced the process of Lactic acid fermentation which allowed the fermentation and preservation of other forms of food.

Combinations of plants and other organisms were used as medications in many early civilizations.

In 1917, Chaim Weizmann first used a pure microbiological culture in an industrial process, that of manufacturing corn starch using Clostridium acetobutylicum to produce acetone, which the United Kingdom desperately needed to manufacture explosives during World War I.
The field of modern biotechnology is thought to have largely begun on June 16, 1980, when the United States Supreme Court ruled that a genetically-modified microorganism could be patented in the case of Diamond v. Chakrabarty.

Applications of Biotechnology

Biotechnology has applications in four major industrial areas, including health care (medical), crop production and agriculture, non food (industrial) uses of crops and other products (e.g. biodegradable plastics, vegetable oil, biofuels), and environmental uses.

Red biotechnology is applied to medical processes.

The designing of organisms to produce antibiotics.

Safer vaccines can be designed and produced by organisms transformed by means of genetic engineering.

Development of tailor-made medicines: creation of drugs based on the proteins, enzymes and RNA molecules that are associated with specific genes and diseases. These tailor-made drugs promise not only to maximize therapeutic effects but also to decrease damage to nearby healthy cells.

Improvements in the drug discovery and approval process
Genetic testing is used for:

Determining sex
Carrier screening, or the identification of unaffected individuals who carry one copy of a gene for a disease that requires two copies for the disease to manifest
Prenatal diagnostic screening
Newborn screening
Presymptomatic testing for predicting adult-onset disorders
Presymptomatic testing for estimating the risk of developing adult-onset cancers
Confirmational diagnosis of symptomatic individuals
Forensic/identity testing
Gene therapy is used to treat genetic diseases.
Cloning.

Green biotechnology is biotechnology applied to agricultural processes.

The selection and domestication of plants via micro propagation.
The designing of transgenic plants to grow under specific environmental conditions or in the presence (or absence) of certain agricultural chemicals.
Improve yield from crops
Reduced vulnerability of crops to environmental stresses
Increased nutritional qualities of food crops
Improved taste, texture or appearance of food
Reduced dependence on fertilizers, pesticides and other agrochemicals
Production of novel substances in crop plants

White biotechnology is biotechnology applied to industrial processes

The using of enzymes as industrial catalysts to either produce valuable chemicals or destroy hazardous/polluting chemicals.
· White biotechnology, also known as industrial biotechnology, is biotechnology applied to industrial processes. An example is the designing of an organism to produce a useful chemical. Another example is the using of enzymes as industrial catalysts to either produce valuable chemicals or destroy hazardous/polluting chemicals (examples using oxidoreductases are given in Feng Xu (2005) “Applications of oxidoreductases: Recent progress” Ind. Biotechnol. 1, 38-50 [1]). White biotechnology tends to consume less in resources than traditional processes used to produce industrial goods.
· Blue biotechnology is a term that has been used to describe the marine and aquatic applications of biotechnology, but its use is relatively rare.
· The investments and economic output of all of these types of applied biotechnologies form what has been described as the bioeconomy.
· Bioinformatics is an interdisciplinary field which addresses biological problems using computational techniques, and makes the rapid organization and analysis of biological data possible. The field may also be referred to as computational biology, and can be defined as, "conceptualizing biology in terms of molecules and then applying informatics techniques to understand and organize the information associated with these molecules, on a large scale."[5] Bioinformatics plays a key role in various areas, such as functional genomics, structural genomics, and proteomics, and forms a key component in the biotechnology and pharmaceutical sector.

Genetically modified organism

Genetically modified organism

A genetically modified organism (GMO) or genetically engineered organism (GEO) is an organism whose genetic material has been altered using genetic engineering techniques. These techniques are generally known as recombinant DNA technology. With recombinant DNA technology, DNA molecules from different sources are combined in vitro into one molecule to create a new gene. This DNA is then transferred into an organism and causes the expression of modified or novel traits.

History

The general principle of producing a GMO is to add genetic material into an organism's genome to generate new traits - Genetic engineering - was made possible through a series of scientific advances including the discovery of DNA and the creation of the first recombinant bacteria in 1973, i.e., E .coli expressing a salmonella gene. This led to concerns in the scientific community about potential risks from genetic engineering which has been thoroughly discussed at the Asilomar Conference in Pacific Grove, California. The recommendations laid out from this meeting were that government oversight of recombinant DNA research should be established until the technology was deemed safe. Herbert then founded the first company to use recombinant DNA technology, Genentech, and in 1978 the company announced the creation of an E. coli strain producing the human protein insulin.

In 1986, field tests of bacteria genetically engineered to protect plants from frost damage (ice-minus bacteria) at a small biotechnology company called Advanced Genetic Sciences of Oakland, California, were repeatedly delayed by opponents of biotechnology. In the same year, a proposed field test of a microbe genetically engineered for a pest resistance protein by Monsanto was dropped

Uses of GMOs

Examples of GMOs are highly diverse, and include transgenic (genetically modified by recombinant DNA methods) animals such as mice, fish, transgenic plants, or various microbes, such as fungi and bacteria. The generation and use of GMOs has many reasons, chief among them are their use in research that addresses fundamental or applied questions in biology or medicine, for the production of pharmaceuticals and industrial enzymes, and for direct, and often controversial, applications aimed at improving human health (e.g., gene therapy) or agriculture (e.g., golden rice). The term "genetically modified organism" does not always imply, but can include, targeted insertions of genes from one into another species. For example, a gene from a jellyfish, encoding a fluorescent protein called GFP, can be physically linked and thus co-expressed with mammalian genes to identify the location of the protein encoded by the GFP-tagged gene in the mammalian cell. These and other methods are useful and indispensable tools for biologists in many areas of research, including those that study the mechanisms of human and other diseases or fundamental biological processes in eukaryotic or prokaryotic cells.

Transgenic animals

Transgenic animals are used as experimental models to perform phenotypic tests with genes whose function is unknown or to generate animals that are susceptible to certain compounds or stresses for testing in biomedical research. Other applications include the production of human hormones, such as insulin.

Frequently used in genetic research are transgenic fruit flies (Drosophila melanogaster) as genetic models to study the effects of genetic changes on development. Flies are often preferred over other animals for ethical reasons and ease of culture, and also because the fly genome is somewhat simpler than that of vertebrates.

· Enviropig
Transgenic plants

Kenyans examining insect-resistant transgenic BT corn.
Transgenic plants have been developed for various purposes: resistance to pests, herbicides or harsh environmental conditions; improved shelf life; increased nutritional value - and many more. Since the first commercial cultivation of GM plants in 1996, GM plant events tolerant to the herbicides glufosinate or glyphosate and events producing the BT toxin, an insecticide, have dominated the market. Recently, a new generation of GM plants promising benefits for consumers and industry purposes is becoming ready to enter the markets.

Since GM plants are grown on open fields, there is often a perception that there could be associated environmental risks. Therefore, most countries require biosafety studies prior to the approval of a new GM plant event, usually followed by a monitoring programme to detect environmental impacts.

Especially in Europe, the coexistence of GM plants with conventional and organic crops has raised many concerns. Since there is separate legislation for GM crops and a high demand from consumers for the freedom of choice between GM and non-GM foods, measures are required to separate GM, conventional and organic plants and derived food and feed. European research programmes such as Co-Extra, Tran container and SIGMEA are investigating appropriate tools and rules. On the field level, these are biological containment methods, isolation distances and pollen barriers.

Government support for and ban of GMOs

The use of GMOs has sparked significant controversy in many areas. Some groups or individuals see the generation and use of GMO as intolerable meddling with biological states or processes that have naturally evolved over long periods of time, while others are concerned about the limitations of modern science to fully comprehend all of the potential negative ramifications of genetic manipulation.

While some groups advocate the complete prohibition of GMOs, others call for mandatory labeling of genetically modified food or other products. Other controversies include the definition of patent and property pertaining to products of genetic engineering and the possibility of unforeseen local and global effects as a result of transgenic organisms proliferating. The basic ethical issues involved in genetic research are discussed in the article on genetic engineering.

In 2004, Mendocino County, California became the first county in the United States to ban the production of GMOs. The measure passed with a 57% majority. In 2005, a standing committee of the government of Prince Edward Island in Canada began work to assess a proposal to ban the production of GMOs in the province. PEI has already banned GM potatoes, which account for most of its crop. In California, Trinity and Marin counties have also imposed bans on GM crops, while ordinances to do so were unsuccessful in Butte, San Luis Obispo, Humboldt, and Sonoma counties. Supervisors in the agriculturally-rich counties of Fresno, Kern, Kings, Solano, Sutter, and Tulare have passed resolutions supporting the practice
Currently, there is little international consensus regarding the acceptability and effective role of modified "complete" organisms such as plants or animals. A great deal of the modern research that is illuminating complex biochemical processes and disease mechanisms makes vast use of genetic engineering.

Crosspollination concerns

Some critics have raised the concern that conventionally bred crop plants can be cross-pollinated (bred) from the pollen of modified plants. Pollen can be dispersed over large areas by wind, animals, and insects. Recent research with creeping bent grass has lent support to the concern when modified genes were found in normal grass up to 21 km (13 miles) away from the source, and also within close relatives of the same genus (Agrostis) .GM proponents point out that out crossing, as this process is known, is not new. The same thing happens with any new open-pollinated crop variety—newly introduced traits can potentially cross out into neighboring crop plants of the same species and, in some cases, to closely related wild relatives. Defenders of GM technology point out that each GM crop is assessed on a case by case basis to determine if there is any risk associated with the out crossing of the GM trait into wild plant populations. The fact that a GM plant may outcross with a related wild relative is not, in itself, a risk unless such an occurrence has consequences. If, for example, a herbicide resistance trait was to cross into a wild relative of a crop plant it can be predicted that this would not have any consequences except in areas where herbicides are sprayed, such as a farm. In such a setting the farmer can manage this risk by rotating herbicides.

The European Union funds research programmes such as Co-Extra that investigate options and technologies on the coexistence of GM and conventional farming. This also includes research on biological containment strategies and other measures that prevent out crossing and enable the implementation of coexistence.

If patented genes are out crossed, even accidentally, to other commercial fields and a person deliberately selects the out crossed plants for subsequent planting then the patent holder has the right to control the use of those crops. This was supported in Canadian law in the case of Monsanto Canada Inc. v. Schmeiser.

'Terminator' and 'traitor'

An often cited controversy is a hypothetical "Technology Protection" technology dubbed 'Terminator. This yet-to-be-commercialized technology would allow the production of first generation crops that would not generate seeds in the second generation because the plants yield sterile seeds. The patent for this so-called "terminator" gene technology is owned by Delta and Pine Land and the United States Department of Agriculture. Delta and Pine Land was bought by Monsanto in August 2006. Similarly, the hypothetical Trait-specific Genetic Use Restriction Technology, also known as 'Traitor' or 'T-gut', requires yearly application of a chemical to genetically-modified crops to reactivate engineered traits. This technology is intended both to limit the spread of genetically engineered plants, and to require farmers to pay yearly to reactivate the genetically engineered traits of their crops. Traitor is under development by companies including Monsanto and AstraZeneca.

In addition to the commercial protection of proprietary technology in self pollinating crops such as soybean (a generally contentious issue) another purpose of the terminator gene is to prevent the escape of genetically modified traits from cross-pollinating crops into wild-type species by sterilizing any resultant hybrids. The terminator gene technology created a backlash amongst those who felt the technology would prevent re-use of seed by farmers growing such terminator varieties in the developing world and was ostensibly a means to exercise patent claims. Use of the terminator technology would also prevent "volunteers", or crops that grow from uncarpeted seed, a major concern that arose during the Starlink debacle. There are technologies evolving which contain the transgene by biological means and still can provide fertile seeds using fertility restorer functions. Such methods are being developed by several EU research programmes, among them Tran container and Co-Extra.