AGRICULTURE BIOTECHNOLOGY
Agricultural biotechnology is a set of tools and disciplines meant to modify organisms for a particular purpose. That purpose can include anything from coaxing greater yields from food crops to building in a natural resistance to certain diseases. Though there are multiple ways to accomplish this goal, the method that tends to get the most attention from the public is genetic modification.
Genes are the basic units of hereditary information. A gene is a segment of deoxyribonucleic acid (DNA) that expresses a particular trait or contributes to a specific function. Genes determine everything from the color of your eyes to whether or not you are allergic to certain substances.
As we learn more about which genes affect different aspects of an organism, we can take steps to manipulate that feature or function. One way to do this is to take genetic information from one organism and introduce it into another -- even if that organism belongs to a completely different species. For example, if you found out that a particular bacterium had a resistance to a certain herbicide, you might want to lift those genes so that you could introduce them into crops. Then you could use herbicides to wipe out pest plants such as weeds while the crops remain safe.
While some people might think that changing organisms at such a fundamental level is unnatural, the truth is that we've been using a much cruder method of shaping organisms for centuries. When farmers crossbreed plants, they are engaging in a primitive form of this methodology. But with crossbreeding, all the genes of one type of organism are introduced to all the genes of the second organism. It's not precise, and it can take generations of plants before farmers arrive at the desired result.
Agricultural biotechnology lets scientists pick and choose which genes are introduced to an organism. Let's take a look at some of the benefits of this technology.
For thousands of years, humankind has used biotechnology in agriculture, food production and medicine.The term itself is largely believed to have been coined in 1919 by Hungarian engineer Károly Ereky. In the late 20th and early 21st century, biotechnology has expanded to include new and diverse sciences such as genomics, recombinant gene technologies, applied immunology, and development of pharmaceutical therapies and diagnostic tests.
The Benefits and Risks of Producing Pharmaceutical Proteins in Plants:-
Protein-based pharmaceuticals traditionally used for the treatment of disease have been made through the expression of protein in bacterial, fungal, and mammalian cell cultures. Recently, the possibility to produce more diverse and complex pharmaceutical proteins in plants has reached the laboratory benches of scientists and companies worldwide. These pharmaceuticals are known as plant-made or plant-based pharmaceuticals. In this article, we will discuss pharmaceutical proteins, how genetic engineering makes it possible to produce proteins in plants, why plants are desirable for the production of pharmaceutical proteins, and which plant systems are being considered for their production. Additionally, we will discuss risk and regulatory issues associated with this new technology.
Proteins as Pharmaceuticals
Proteins are essential to all living organisms for function, structure, and regulation of the body. Protein development in a cell begins with DNA transcribing into RNA, and RNA translating into proteins. Proteins are made up of amino acids that are arranged in different combinations and lengths. The differences in arrangements and lengths of amino acids determine the function of the protein. Some examples of proteins include hormones, enzymes, and antibodies.
Many people suffer from infectious, inflammatory, and cardiovascular diseases — and these numbers are growing. Protein-based drugs are the fastest growing class of drugs for the treatment of these diseases in humans and other diseases in animals. The reasons for this are because the numbers of people with diseases such as diabetes are growing and new technologies are making proteins easier to produce. The current methods of production of proteins for pharmaceutical application (mammalian, bacterial, and fungal cell cultures) are predicted to fall short of demand in the near future (Rogers 2003).
Insulin was the first pharmaceutical protein produced using genetically engineered bacteria (Thomas et al. 2002). Insulin originally was isolated from cows and pigs that were slaughtered for food. This method was inefficient and caused some patients to develop allergies from the animal-derived insulin. Today it is made from the human gene that codes for the insulin protein and is expressed and cloned in the bacterium, Escherichia coli. Large quantities of E. coli are now grown in fermentation vats to make tons of human insulin available to the growing number of diabetic patients.
Plant Transformation
Genetic engineering also has made it possible to use plants as factories for pharmaceutical protein production. Plant-made pharmaceuticals are made by inserting a segment of DNA that encodes the protein of choice into plant cells. The plants or plant cells are essentially factories used to produce the desired proteins and are only grown for the purpose of pharmaceutical applications.
There are two common methods of transformation (the process by which DNA from one organism is incorporated into the DNA of another organism) that have been established through biotechnology to produce transgenic plants, which, in turn, could be used to create the plants used to make pharmaceutical proteins. The transformation techniques include theAgrobacterium tumefaciens-mediated transformation system and biolistics, also called particle bombardment.
Agrobacterium tumefaciens is a bacterium that naturally infects plants and causes crown gall disease. It is very useful for the production of transgenic plants because it has the amazing ability to transfer a segment of its DNA, called T-DNA, into the nucleus of the plant cells. The T-DNA from A. tumefaciens is then integrated into the plant and transcribed, causing crown gall disease. Scientists have used A. tumefaciens to their advantage by inserting their DNA of interest between the T-DNA to create a plant with qualities such as herbicide resistance, or pesticide resistance, as well as many others (Nester et al. 1984, Binns and Thomashow 1988). Crown gall disease does not occur in the plant after being transformed by A. tumefaciens because the plasmid has been constructed to disarm the tumor-inducing properties that cause the disease, and instead it expresses the DNA of interest.
Biolistics, or the Particle Bombardment Transformation System, employs the use of metal particles either of gold or tungsten. The metal particles are coated with the DNA that is to be transferred into the plant cells. Using a pressurized system, a plastic bullet coated with metal and DNA particles is released from the biolistics machine when the pressure is released. The bullet is shot, and within seconds, stopped by a shield causing the metal coated DNA particles to be knocked off the bullet. The particles are then ultimately forced to be inserted into the plant cells below.
Once the genes have been transferred into the cells, the cells expressing the gene of interest must be selected. In most cases, a selectable marker is included with the DNA construct, which will confer resistance to an antibiotic or herbicide. The plant cells that survive the antibiotic or herbicide application are the ones that have successfully received the gene of interest (Purdue Agricultural Biotechnology 2004).
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