Genetic engineering. You might have heard of it from a friend, or maybe it was brought up on the news. But what is it and how does it affect bananas?
What is genetic engineering?
Genetic engineering is a branch of synthetic biology that uses technology to modify genes in living organisms. This is opposed to methods such as selective breeding where the genes are not directly modified but individuals with randomly occurring genes beneficial to the breeder are selected. Genetic engineering involves a variety of different technologies used to read, create, cut and paste genes among other functions. Many new technologies are currently being developed to make executing these functions easier and more efficient. As a result, this field of science is rapidly growing and is becoming much more important in the modern world.
When was genetic engineering invented?
While humans have been selectively breeding animals and plants to have favourable traits for millennia, the modern form of this science has only been around for 50 years. Although the term was coined in the 1951 book “Dragon’s island,” the first successful fusion of 2 pieces of DNA was achieved a whole 2 decades later in 1972. This was done by Nobel Prize recipient Paul Berg, with this variety of strands being known as recombinant DNA (rDNA) and the techniques developed from this experiment and the ones leading up to it were used as the base for many discoveries later on. The year 1973 brought the world's first transgenic organisms and a transgenic mouse was created a year later. Transgenic organisms are organisms with foreign genes transferred into their genome through natural means or otherwise. Still, these significant advancements led to ethical concerns from the general scientific community. These concerns culminated in the Asilomar Conference of 1975 where it was recommended that the newly discovered DNA recombination technology should be kept under government oversight. This was to continue until the technology was deemed safe to prevent hazards as it was still unbroken ground and its risks were unknown. Throughout the next decade, many significant advancements were made in the use of GMO organisms in medicine starting from when the company Genentech was able to produce insulin via GMO bacteria in 1978. This insulin would eventually become FDA-approved.
How do you even genetically engineer something?
Changing an organism's genome is a complex multi-step process that involves building on past research. These processes can be divided into 2 general categories. Constructing the correct gene and adding this gene to the genome of the organism.
To create a GMO bacterium, the first thing scientists have to do is to either find a gene in a different organism or in a mutated version of the same one that does what they want the final organism to do. They start by looking for individuals with the desired traits and map their genes* to find the exact strands of DNA that cause this trait to happen. They then extract a cell containing this gene and open it up by gently breaking down the cell walls with enzymes -this is done not to damage the DNA inside. Although sometimes more force is needed when the cell membrane is tough (in the case of certain plants), forceful methods generally are avoided as it damages the DNA. The specific gene is then separated from the cell by being cut out in lumps using special enzymes called restriction enzymes. This is where polymerase chain reaction (PCR) is used to clone the fragments into a large enough sample to be reliably extracted from the cell. After the gene has been extracted from the cell, it is then inserted into a part of a bacterium called the plasmid; a small DNA molecule that lies outside the main DNA clump of the bacteria which serves the function of providing it with auxiliary functions such as antibiotic resistance. Due to its isolated nature, it’s much easier to insert the foreign DNA into the plasmid as it doesn't disturb the basic functions of the bacteria. This is so that the gene can be easily cloned when this bacteria duplicates allowing for an unlimited copy of this specific gene. Additionally, this also allows the gene to be stored for an indefinite amount of time when the bacteria is frozen. Depending on the final goal of the project, this GMO bacteria could be the finished product, as is the case with the earlier mentioned insulin bacteria developed by Genentech. In other more complex projects, where the final goal is the modification of a plant, this bacteria could be used to insert foreign DNA into the cells of a plant.
In the case of other organisms such as animals or plants, after foreign DNA has been taken from its original host, there are a variety of different methods used to insert it into the cells of the recipient. For example, a common method of inserting DNA into animal cells is through microinjection. This method generally uses a glass needle less than 0.2 µm* in diameter to directly send DNA into the target cell. Microinjection has many unique advantages which warrant its wide usage. Such as being able to control how many cells are injected, allowing the injection of precise amounts of DNA, and having a much higher success rate than other methods. For plants, genetic modification can be done with the previously mentioned GMO Agrobacterium, which has the ability to insert its DNA into other cells. Also, modification through physical methods known as biolistics is commonly used. Biolistics involves the use of a small calibre firearm or airgun to shoot heavy metal particles (gold or tungsten) coated in genetic material directly into a clump of cells. Because all of these methods only affect a single cell or a small group of them, it is necessary to facilitate the transfer of genetic material early into the life of a multi-celled organism. For animals, this means that the DNA has to be inserted into an early stem cell so that it can be replicated when the animal grows. For plants, however, the entire organism must be regenerated from this single modified cell (or clump). To finish this entire process, the organism is then checked for the presence of the modified gene by finding special genetic markers left by the scientists at an earlier stage.
*µm = 1 millionth of a metre or micrometre
What are the usages of genetic engineering? (banana time)
As time passes, more and more aspects of human life are affected by developments in genetic engineering; it is rather difficult to cover everything in a single article but we will go through 2 different major usages of this technology.
One of the most important yet controversial uses for GMOs in the agricultural industry. Firstly, this technology is used to create plants with many beneficial traits such as increased nutritional value, resistance to pesticides, and even resistance to the pests themselves. They can also be used to make the crops more resistant to abiotic stresses such as drought, cold or even increased salt in the soil. An interesting case of GMOs being useful in making a plant hardier is the transgenic cavendish banana. Although the banana industry is truly massive, in the 1990s, a fungus known as TR4 was discovered to be killing cavendish bananas in Southeast Asia. Normally this would be solved with some fungicides and the burning of infected trees, but this fungus couldn't be controlled by such means. In 2012 TR4 was discovered in the Middle East. Only a year later this fungus was discovered In Mozambique too! Since then, TR4 has invaded almost every banana-growing region in the world (except the Americas) and has caused the loss of an innumerable amount of plantains (tragic). This is where GMO technology comes in, biotechnologists James Dale and his colleagues at the University of Technology in Brisbane were able to clone and insert genes from a species of banana that is naturally resistant to TR4 into the much sweeter and more nutritious cavendish variety. In tests, this transgenic plantain was able to survive in fields containing TR4 while up to 100% of their unmodified variants were showing signs of infection such as rotting trunks and wilted yellow leaves. This banana also didn't show any significant decrease in crop yield or even a change in taste. GMO technology can also be used in animals to make them produce foreign substances in their milk or even grow faster.
Since the beginning of GMOs’ existence, their usage in the medical field has been extremely prevalent and widely useful. This is because they can be used in the creation of drugs like insulin, vaccines, growth hormones, and many others. Additionally, scientists have even developed novel technologies such as viruses that cause immunity but aren't actually harmful to the recipient; as shown in the vaccine for Foot and Mouth Disease. This is a devastating disease that kills massive amounts of livestock and is hard to cure. One other important use of GMO technology is to create lab animals that have similar genetics to humans, this is a massive breakthrough because it makes finding cures to rare and deadly diseases vastly easier and can also allow scientists to test novel cures to more common diseases such as Parkinson's and heart disease. GMO mice have even been used to find ways to delay ageing.
Are GMOs dangerous and how ethical are they?
GMOs have always been an extremely controversial subject: These controversies can be separated into 3 main categories, ethical, health-related, and environmental. One of the main ethical concerns raised by critics is that by modifying living organisms, scientists are playing God. Although this issue is mainly limited to certain religious circles, it is one nonetheless. Other ethical concerns such as potential problems with modifying humans (nonconsensually) and the idea of patenting life are also commonly raised. As for the question of whether GMO foods are harmful for your health? The general consensus within the scientific community is that GMO foods generally should pose no additional threat to your health other than the threats posed by the original organism. But due to the variety of GMOs and the constant modification of new organisms, this statement should be tested on a case-by-case basis. The final controversial category is environmental problems posed by GMO developments, the most pressing of which is the increased risk of ‘superweeds’ and other pests developing via transfers of transgenes. Superweeds are created when transgenes planted in a herbicide-resistant crop are unintentionally transferred into a weed. This leads to the weed becoming resistant to the herbicide and becoming a massive problem for farmers. With the recent introduction of modified commercial fish, concerns have also been raised warning about the environmental effects that may occur should these fish escape. The environmental consequences of these ultra-fast-growing fish are unable to be tested (obviously). However, the chance of these fish actually causing a problem appears to be minuscule at worst and may even benefit the ecosystem in some ways (more food for predators). It should also be noted that these fish have very little chance of actually being able to successfully reproduce and so their genes won't be passed on to their offspring. Probably…
By Anik Ratta
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