Modern Biotechnology: A Brief Overview
There are numerous terms and acronyms used in the area of biotechnology that can be confusing. Also, many countries use the same term to mean different things. For example, the European Union's definition of GM is the same as Canada's interpretation of GE. The following is the Canadian Food Inspection Agency's (CFIA) attempt at addressing some commonly used terms, of which only "biotechnology" and "novel trait" are used in CFIA legislation.
"Biotechnology" means the application of science and engineering in the direct or indirect use of living organisms, or parts or products of living organisms, in their natural or modified forms. This term is very broad and includes the use of traditional or conventional breeding, as well as more modern techniques such as genetic engineering.
"Modern biotechnology" is used to distinguish newer applications of biotechnology, such as genetic engineering and cell fusion from more conventional methods such as breeding, or fermentation.
Most often the term "biotechnology" is used interchangeably with "modern biotechnology".
"Conventional breeding" or "selective breeding" means propagating plants or animals sexually, selecting for certain traits. Using selective cross-breeding, people can produce different varieties of plants and breeds of animals.
GM stands for "genetically modified". An organism, such as a plant, animal or bacterium, is considered genetically modified if its genetic material has been altered through any method, including conventional breeding. A "GMO" is a genetically modified organism.
GE stands for "genetically engineered". An organism is considered genetically engineered if it was modified using techniques that permit the direct transfer or removal of genes in that organism. Such techniques are also called recombinant DNA or rDNA techniques.
Some international agreements like the Cartagena Protocol on Biosafety use terms like "living modified organism" (LMO). The Protocol defines a LMO as a microorganism, plant, or animal that has been derived through modern biotechnology-using techniques such as recombinant DNA-that is capable of transferring or replicating its genetic material (DNA, or "deoxyribonucleic acid", is the genetic material found in all living organisms).
"Transgenic" organisms have a gene from another organism moved into them. For example, the plant product known as "Bt. corn" is a transgenic plant because it has a gene from the bacterium Bacillus thuringiensis, or Bt. That gene produces a protein with pesticidal properties that, when incorporated into a plant, allows the plant to produce this protein, thus transferring the bacteria's natural defence to the plant.
"Mutagenesis" is the use of methods to physically change or "mutate" the genetic sequence, without adding DNA from another organism. Various chemicals and ionizing radiation can be used to invoke these changes. "Site-directed mutagenesis" can also be used to invoke changes in specific genes. In plants, such agents are used to change a plant's genetic sequence, and the plant can pass on these new characteristics to its offspring.
A new product may be considered "novel" if it has:
- a new trait(s) or characteristic(s), or
- a changed trait(s) or characteristic(s), or
- a new use as a food or livestock feed
PNT stands for a "Plant with a Novel Trait". The word "novel" may remind you of a work of fiction, but it also means "new"-a PNT is a plant that has a new trait or characteristic. A plant is considered to be a PNT if has trait(s) that are novel to that species in Canada. That is:
- the new trait is not present in stable, cultivated populations of the plant species in Canada, or
- the trait in the plant species is present at a level significantly outside the range of that trait in stable, cultivated populations of that plant species in Canada.
Traditionally, plants have been given new traits through selective breeding. Modern science gives plant breeders newer methods of introducing novel traits into plants, including mutagenesis and genetic engineering/rDNA. Canada is the only country that assesses plants and novel livestock feeds that have new traits introduced by any technique, including traditional breeding techniques and mutagenesis because the new traits may have an impact on the environment.
A "novel feed" is livestock feed comprising an organism or organisms, or parts or products thereof, that:
- is not set out in Schedule IV or V of the Feeds Regulations, or
- has a novel trait (as defined in the Feeds Regulations).
Novel livestock feeds are composed of or derived from one of these sources: microbial, plants, or animal.
How does Biotechnology Work?
Biotechnology, through genetic engineering, works directly with the genetic material of a cell. If we examined a cell under a high-powered microscope, we would see long, thread-like structures called chromosomes. These chromosomes, composed of DNA (deoxyribonucleic acid), are organized into sections called genes. Genes control the production of particular proteins, and proteins, in turn, determine the characteristics of an organism. In some cases, a gene may govern one particular trait, such as an organism's resistance to disease, while in other cases, characteristics may be determined by many genes. It was the understanding of DNA that paved the way for genetic engineering. The knowledge gained has allowed researchers to transfer genes between the cells of different organisms.
Cut and Paste Method
The actual transfer of a gene is carried out in a complex "cut and paste" procedure. Specialized enzymes are used to "cut" or remove a specific gene from one organism's DNA, and then to "paste" or slice that gene back into the DNA of another organism. The gene can be inserted into another organism through a variety of techniques, depending upon the characteristics and properties of the recipient organism, and whether the organism is an animal, bacterium or a plant.
Some of the genetic engineering techniques used to modify organisms are:
A technique called micro-injection is the method often used to produce genetically engineered or transgenic animals. Through this technique, a very fine needle is used to inject a solution of DNA molecules containing genes that carry desired characteristics (such as disease resistance) into animal cells, usually at the embryo stage. The genes are incorporated into the animal cells genetic material, and the cells begin to express the characteristic determined by the new gene. Applying this micro-injection technique could have potential benefits for agriculture as well.
In certain bacteria, small naturally occurring circular segments of DNA called plasmids are found, which can be used for genetic engineering. Plasmid DNA can be taken outside of the bacterial cell, modified with the addition of a new gene, and placed back into the cell. With the new gene, the bacterial cell can now manufacture the product of this gene as its own. Because bacteria reproduce very rapidly, large volumes of bacteria containing the modified plasmid can be used to produce commercially significant quantities of a gene product, such as a food additive or an animal vaccine, in short periods of time.
Plant cells have tough outer walls, making the delivery of genes into the plant cells a little more challenging than is the case for bacteria. There are two main techniques by which this process is carried out.
The first of these involves the use of a modified species of bacterium called Agrobacterium. In nature, the Agrobacterium invades a plant, then infects it with a segment of its own DNA that "codes" for the development of crown gall disease. This DNA is incorporated into the plant's DNA and the plant becomes diseased with crown gall.
When using Agrobacterium to genetically modify plants, these disease-causing parts of the Agrobacterium's DNA are removed. They are replaced with genes that carry desired characteristics (such as improved nutritional value) by the "cut and paste" procedure.
The Agrobacterium can then be introduced to plant cell material, where it is allowed to invade plant cells, and introduce the new gene with the desired characteristics. The full plants grown from these plant cells express the characteristic determined by the new gene. Agrobacterium, therefore, is a convenient delivery system by which new characteristics can be passed on to plants.
Particle Gun Method
The second technique used to deliver genetically engineered DNA into plants is the DNA "particle gun" method. Tiny metal particles coated with genes with desired characteristics, such as improved nutritional value, are put into a particle gun and fired directly into plant cells. These genes are incorporated into the plant cell's DNA, and the cells are then grown into full plants. The new characteristic is thereafter present in the whole plant.
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