Genetic engineering is the technique that gives the power to desirably manipulate the genome of an organism. This ability has been explored and experimented in several organisms, some of which have been commercialized whereas the practical applications of some are being tested.
The first genetically modified organism was created by Herbert Boyer and Stanley Cohen in 1973. It was a bacterium Escherichia coli that contained genes for antibiotic resistance.
Genetic engineering refers to a fast-growing technology that enables modifications in the genetic make up of an organism. This includes addition of new gene(s), deletion of gene(s) or even manipulation of the existing genes to introduce or get rid of specific traits and characteristics.
The resultant organisms, containing a genome altered in such a way, are collectively termed as genetically modified organisms (GMOs). In case of manipulation by addition of genes, the organisms which contain genes added from a different variety of the same species are called cisgenic organisms; whereas those containing genes from a foreign species are called transgenic organisms.
Since the first successful attempt in 1973, several organisms were experimented with, giving rise to several interesting genetic engineering examples. Some of the significant ones have been described below.
Insulin injection is a routine part of diabetes treatment today. But this insulin actually comes from a genetically engineered strain of E. coli. Prior to this, insulin was sourced from pancreas of pigs and other animals.
At the well-known biotech company Genentech Inc. (short for Genetic Engineering Technology), scientists were exploring genetic engineering to develop human hormones in bacteria. One of the examples include the development of E.coli that produced human insulin. For this, they isolated the human gene for insulin, and accordingly designed a gene that would specifically produce human insulin protein, when inserted in the bacterial genome. These man-made genes were introduced in the bacterial genome to get the production of insulin on a large scale.
In 1982, this synthetic insulin was approved by U.S. Food and Drug Administration (FDA). Sold under the brand name Humulin, it is the first-ever therapeutic product that was generated through genetic engineering. This genetic engineering attempt not only changed the scenario for treatment of diabetes, but for several other conditions as well. Now owned by F. Hoffmann-La Roche Ltd., Genentech continues to be known as the founder of the biotechnology industry.
The ability to modify plant genomes and introduce genes for a specific desired trait into a desired plant, gave rise to an array of experiments on several commercially important crops. Several biotech companies developed seeds for plants that are disease-resistant, pest-resistant, herbicide-resistant, or that give high yields. But, in order to protect their intellectual property rights, a new technology known as the Genetic Use Restriction Technology (GURT) or Terminator Technology, was born. The seeds generated through this technology are called terminator seeds or suicide seeds.
The characteristic feature of terminator seeds is their ability to generate plants that give rise to sterile seeds. In simple terms, a farmer buys the seeds, sows them to reap a good harvest of a crop that is genetically modified to possess a desirable trait. But, the new seeds that are formed in these genetically modified (GM) crops are sterile and cannot be used for the next season. He has to buy the seeds again.
An advancement over this technology is the development of a genetically engineered crop that yields sterile seeds, but the desired trait that has been engineered will be functional only when an inducer chemical is administered. This inducer chemical needs to be purchased from the respective company. Thus, the farmer may save the seeds from his harvest but needs to purchase the inducer every year.
A huge controversy surrounds this technology since its proposition by Monsanto in the 1990s, with claims that it is a new way to rob farmers and make profits. But the proponents argue that they need to make up for the costs incurred in developing the technology. Apart from protection of intellectual property, the biggest advantage conferred by such a technology is that it prevents the genetically altered trait from spreading to wild plants, which is one of the risks involved in use of GM crops. Nevertheless, the agribusiness giant agreed not to commercialize terminator seeds.
Certain organisms possess a natural ability to produce light through a chemical reaction, a property known as bio luminescence. It is more commonly seen in marine animals, and the most famous example is a type of jellyfish called Aequorea victoria. It produces a protein called green fluorescence protein (GFP) that confers the ability to glow.
This protein was discovered and engineered by a trio of scientists, who won the Nobel Prize in Chemistry (2008) for their work. Later, the gene for GFP was introduced in an array of organisms leading to the development of genetically engineered glow-in-the-dark bacteria, fungi, plants, fish, mice, cats, dogs, marmosets, rabbits, pigs, etc.
GloFish is a genetically modified, fluorescent variety of zebrafish that has been trademarked by Yorktown Technologies. Varieties of this GloFish are available in different colors, including red, green, purple, etc., in several pet stores in USA. It is the only genetically modified pet that is commercially available.
This gene revolutionized genetic engineering techniques by providing a way to see the expression of genes. When combined with the gene of interest and introduced into an organism, it serves as a visible tag to know if the particular gene of interest has been expressed or not.
Imagine a drug factory containing an array of chickens that lay eggs loaded with medicinal proteins. Some scientists are trying hard to ensure that such a day arrives soon.
A group of scientists at the Roslin Institute in Scotland, have developed a GM chicken that lays eggs containing medicinal proteins. Egg-whites are naturally loaded with a protein called ovalbumin. What the group of scientists did was introduced the gene for a foreign protein, instead of the ovalbumin gene, in a set of chickens. Consequently, the eggs of these GM chickens were loaded with the foreign protein.
Although a bit bizarre, this attempt if successful, will provide an easy way to generate large amounts of medicinal proteins useful for treatment of anemia, certain cancers, hematological disorders, etc. The ultimate result one may expect is availability of these drugs at comparatively lower prices.
Cows that Make Human-like Milk
How cool would it be if you could drink a bottle of milk, and get nutrition as well as antimicrobial agents!
There is a significant difference in the composition of cow milk and human breast milk. Apart from nutrients, human breast milk contains a variety of antimicrobial agents as well as antibodies and other proteins required for immunity. These proteins are vital for proper development of the immune system in infants, as well as to maintain a healthy gut microflora.
At the State Key Laboratory for Agrobiotechnology in China, a group of scientists developed transgenic cows that were engineered to produce an antimicrobial enzyme that is present in large amounts in human milk. In another set of experiments, they genetically engineered cows to produce milk containing certain immunity-providing proteins of human milk.
As a step ahead, they have managed to develop cattle that produce milk with a fat content similar to that of human milk. They claim that in cases where lactation is not feasible, such humanized milk can prove to be a better substitute rather than the infant formulas.
Ever wondered why fish do not freeze even at extremely low temperatures? What if this property could be transferred to fruits and vegetables, and be able to preserve them for a long time. In an attempt to explore this idea, scientists isolated a gene that makes an antifreeze protein in a fish called winter flounder, which is known to survive in extremely cold conditions.
This gene was integrated into the DNA of tomato plant cells, which were used to develop a new variant of tomato plants. Whether these tomatoes were frost-resistant is still unclear, and were never commercialized. However, they became the center-point of the huge debate over the development and commercialization of GM crops, and are infamously known as fish tomatoes.
Cress that Detects Land Mines
The safe removal of land mines is a major challenge; and progressing at the current rate, removal of all the mines that have been laid till now would take more than a thousand years. Therefore, the need to develop a method to tag land mines, and avoid the innumerable accidents that occur during de-mining, is immense.
With this intention in mind, a company called Aresa Biodetection (Copenhagen, Denmark), has developed a GM thale cress (Arabidopsis thaliana), the favorite model of botanists and geneticists. This genetically engineered plant changes its color from green to reddish brown in the presence of land mines. Such a change occurs when the roots of the plant detect nitric oxide that evaporates from the explosives present in land mines. This detection system is active once the plant is 3-5 weeks old, and hence offers not just safe but faster way to spot land mines as compared to the current methods.
However, the practical applicability of this method is still not clearly evaluated. The company stopped its research on thale cress in 2008, and closed down in the following year.
Although the arena of biofuels is being explored since the time of Henry Ford, only 10-20% of the fuel demand can be met through the currently available biofuels. In addition, the biofuel must be compatible with the current vehicle technology or should not demand significant technical modifications.
As a step towards this goal, a group of scientists at the University of Exeter (UK), genetically modified the pet experimental bacteria E. coli. This bacteria is known to produce certain long chain alkanes in order to build its cell membranes. Through genetic modification, the metabolic pathways of this organism were altered such that it produces and secretes hydrocarbons similar to those present in diesel. These hydrocarbons can be easily purified and used as a replacement for diesel.
Although at a preliminary stage as yet, this genetic engineering example has contributed significantly to the progress in biofuel techniques.
Singing in mice has been reported by several scientists from all over the world, however, the frequencies at which they sing is not audible to humans. Especially famous is the Alston’s brown mouse or Alston’s singing mouse. It would be surely interesting if we could hear these songs too.
At the University of Osaka in Japan, geneticists were trying to study the effects of mutations in a strain of genetically engineered mice that are prone to mutations. One of the effects of a mutation may have altered vocalization in the mice, and a mouse that could sing at frequencies audible to humans was born.
This accidental genetic modification may provide an easy way to study communication patterns in mice as well as its similarities and differences with respect to other mammals.
Scared of an injection but need to get vaccinated? Simple. Eat a banana and get vaccinated for diseases like cholera and hepatitis. Known for their high potassium content but infamous as high-fat fruits, bananas are one of the contenders in the development of edible vaccines.
A gene for the antigen required for immunity against a specific pathogen is introduced into the banana genome such that the antigen is present in the bananas. When an individual eats the banana, the antigen is picked up by certain specialized gut cells which initiate a cascade of immune processes. An immune memory for the antigen is generated, and the person is vaccinated for the respective disease.
Other plants being developed to produce edible vaccines include tomatoes, potatoes, corn, rice, wheat, soy, etc., with target diseases including malaria, cancers, hepatitis B, gastroenteritis, etc. But, an even more amazing advancement would be if the immunity could be passed to developing fetus. A pregnant woman eats a fruit or vegetable, gets vaccinated, and passes the chemical information required for immunity to the fetus.
Mosquito is considered to be the most dangerous animal, since it has killed more humans than any other animals, as well as killed more humans than even wars and plague. What if this same mosquito is used to prevent the spread of diseases?
Aedes aegypti is the mosquito species responsible for the spread of dengue, yellow fever, and chikungunya. An interesting fact about them is that only females can bite and thus transfer the pathogenic virus. A single female lays about 500 eggs in her lifetime.
On the other hand, the male mosquito cannot bite since it does not have the mouth parts for biting. The more important fact about this male is that it is exceptionally adept at finding the female mosquitoes. Taking advantage of these two properties, scientists at the Oxford University developed the male mosquito that carries a gene which results in the death of the offspring. In a field experiment in Cayman islands, this technique yielded about 85% reduction in the mosquito population in four months.
A production unit at Oxford is being developed to produce such mosquitoes on a larger scale with plans of producing about 20 million mosquitoes in a single week.
Genetic engineering has opened up an array of approaches to tackle several challenges, that are not just limited to the medical community. However, this technology has to cross several hurdles including safety concerns, stability of the resultant GMOs, transfer of genes into the wild, as well as ethical and social issues.