With a new age of technology, many controversies surround the issues of high-tech science that have a direct impact on our lives. An example of this includes GMOs, or Genetically Modified Organisms. As every science article or video says, humans have been genetically modifying organisms for thousands of years. In fact, genetic modification is way more common than you might think. From agriculture to animals, we've been changing our world since the beginning of civilization.
To illustrate, humans began changing crops through a process called "selective breeding". This is a method that involves selecting organisms with the most desired traits, and breeding it to pass on these traits to the offspring. Throughout many generations of selective breeding, organisms may begin to show different traits. For example, the size of corn plants has grew by more than 10 times, mostly because of selective breeding. However, selective breeding isn't completely safe even though there aren't any super high-tech equipment involved. Pets are also commonly bred for desired traits, as humans have bred dogs and other pets to fit our needs through inbreeding and selective breeding, ultimately leading to unhealthy animals. One notable example of this is the French Bulldog, which has been selectively bred and manipulated to the point of extreme medical issues, such as heart, hips, eyes, skin, and severe breathing problems. They are also unable to reproduce naturally, which means that bulldogs as we know it can't exist without human help. A veterinary professor at Leipzig University, Dr Gerhard Oechtering stated, "It is unbelievable that we need invasive surgery just to repair the basic needs of the dog. Breathing is the most basic need and this is no way acceptable from any ethical point we have today." Even without modern technology, our reckless selective breeding have led to catastrophic issues.
While selective breeding isn't what we mean when we say genetic modification, it shows that humans have changed the DNA of many things around us.
This infographic summarizes how the CRISPR/Cas9 system works! Image Source
However, genetic engineering in GMOs is done through a process that removes the genes of one organism to insert into another. One of the most common and efficient systems for genetic engineering is the CRISPR-Cas9 system, which stands for Clustered Regularly Interspaced Short Palindromic Repeats and CRISPR-associated protein 9. This process uses a naturally-occuring gene editing system in bacteria that is normally used as an immune system to protect the bacteria from bacteriophages. In the CRISPR DNA sequence, there are short palindromic repeat segments of DNA that are all identical. However, between these DNA repeats, there are segments of DNA called spacer DNA that are all different, unlike the DNA repeats. Other CRISPR associated genes included the Cas genes, which makes Cas proteins that are helicases (which unwind DNA) or nucleases (which cut DNA). When a bacteria is infected by a bacteriophage, the Cas genes make a Cas protein complex armed with crRNA (CRISPR RNA), which are transcribed from the spacer DNA that contain the DNA of bacteriophages from previous infections, then cuts apart and destroys the DNA from the current bacteriophage infection. For a bacteria, this is generally how their immune system works. However, in gene editing, scientists use a specific bacteria called the Streptococcus pyogene. This bacteria has a Cas9 protein, and scientists insert a piece of gRNA (guide RNA) into the Cas9 protein. The gRNA will bind to a specific sequence of DNA in the cell, and Cas9 will cut the DNA. To summarize, gRNA allows scientists to cut a section of DNA in specific targeted places. When the DNA is cut, the cell will attempt to repair it, and sometimes the DNA will become deactivated. This could be useful for disease treatment since scientists can figure out a way to deactivate genes that cause genetic illnesses. To add new DNA into the sequence, we can cut the DNA with Cas9 and insert a piece of RNA, which the cell will repair the DNA with the new piece of RNA.
Multiple studies around the world have found that GMOs are safe! Image Source
However, common uses for genetic engineering includes in food and medicine, but there are many ethical and safety concerns that surround this. In particular, GMOs are extremely common in the agriculture industry. Currently, more than 90% of corn, soybean, cotton crops grown in the US are from GMO seeds. Crops are typically modified for traits like herbicide tolerance, which allows farmers to use weed killers such as glyphosate without harming the crops, insect resistant, which allow the crops to be naturally insect repellent without the use of pesticide, disease resistance, which allow crops to fight off specific diseases, and crop enhancement, which are grown to meet consumer satisfaction, such as a non-bruising potato. One of the main concerns about GMOs in food involves the increased use of herbicide due to herbicide tolerance in crops. Farmers can now use herbicide everywhere, damaging the ecosystem as it is known that herbicides can cause severe harm to wildlife. Additionally, while some may worry over the pest resistant GMO crops because of their ability to kill pests, these GMOs actually only target insect anatomy. Some things are toxic to animals, but not to humans, such as chocolate and coffee. Insect resistant crops can in fact be beneficial to the environment. To illustrate, in Bangladesh, eggplants are an important crop. However, local farmers were often plagued with insects killing their crops, so they needed to use large amounts of pesticide. When GMO eggplants were introduced, this reduced the need for pesticide and subsequently improved the health of farmers and wildlife. Even though GMOs could pollute and damage our ecosystem, they also have the ability to reduce our usage of pesticide and improve sustainibility. So are GMO crops safe for consumption? According to Megan L. Norris, "To this end, many different types of modifications in various crops have been tested, and the studies have found no evidence that GMOs cause organ toxicity or other adverse health effects". In addition, in experiments carried out by South Dakota State University found that there was no difference in reproductive or developmental health between multiple generations of rats that ate GMO vs. non-GMO corn.
Victoria Gray was the first patient with a genetic disease to be treated using CRISPR! Image Source
Another common usage of genetic engineering is in healthcare. While there are many stories of the possibility of genetically engineering embryos to have the perfect traits, gene editing to cure diseases is more oftenly explored by scientists. The possibility of curing both infectious and genetic diseases is promising, as CRISPR/Cas9 can delete or add genes. In single-celled organisms, editing an organisms genome is simple. Yet, in multi-celled organisms like humans, distributing CRISPR/Cas9 to the entire human body is much more complicated, even though CRISPR/Cas9 has the ability to cut the DNA at multiple places. When editing somatic cells, these changes aren't inheritable and will die with the organism. However, if we edit germline cells (egg and sperm cells), this could change the course of human genetics and evolution forever. Germline cells are inheritable, so what would happen to humans evolution if we artifically changed the human genome? CRISPR/Cas9 can also treat other diseases, such as HIV or cancer. Scientists have researched the possibility of curing cancer by genetically editing immune system cells to recognize and attack cancer cells. With new technological advances, we may be able to eradicate cancer with genome editing techniques one day. The field of genetic engineering is incredibly promising in treating life threatening illnesses, but holds an uncertain future for the future of genetics and evolution.
Technology has changed immensely within the past century, and the field of genetics and biotechnology is sure to change too. Even without genetic engineering, the course of evolution has been changed by selective breeding and genetic counseling. While GMOs in food has been proven to be generally safe for human consumption, the problem of corporations controlling our food supply through herbicide production reveals the dark side of using GMOs. However, developments in genetic engineering provides an optimistic opportunity for a disease-free and sustainable world.
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