Scientific Discovery of CRISPR-Cas9 in Gene Editing
Limited scientific explorations can revolutionize a field within a short time, but experts are currently able to manipulate cells unimaginably, all due to a CRISPR (clustered regularly interspaced short palindromic repeats) technology. As biologists continually sharpen instruments for deleting, replacing, and modifying DNA, CRISPR strategy has evolved into a popular genome engineering method. It provides total domination over genes in countless species through the utilization of modified bacterial protein and RNA guiding into particular sequence of DNA. Through related studies stating CRISPRs functionality in bacteria a recent discovery by co-inventors Jennifer Doudna, Emanuelle Charpentier and Feng Zhang discovered the botanical capability of Cas9, the RNA-managed DNA bisected enzyme that edits genes (Hsu, Lander & Zang, 2014). Currently, scientists are harnessing the basic potential for various implementations, such as in agricultural advancements, eradicating contagious ailments, and anthropoid therapeutics.
The Link Between CRISPR-CAS9 and Genome Editing Technology
Gene editing is the procedure whereby DNA sequences are modified inside s living cell’s genome. Valuable devices of bacteria gene rewriting have been in existence. Still, the capacity to edit DNA in eukaryotic cells, housing the genome in a different edifice known as the nucleus, hanged back. During the 1990s, a new strategy for greatly productive gene editing had emerged; if one could induce a specific DNA break at a particular gene, then one could significantly enhance ability to edit the gene (Sternberg, 2017). Paradoxically, localized DNA damage is the one that would be the stimuli for DNA repair. The perfect tool would be a programmable nuclease, an enzyme that slits nucleic acids just like in DNA, and scientists can easily program to introduce breaks in some DNA sequences in the cell (Chandrasegaran & Carroll, 2016). Some tools came into existence in the 1990s and 2000s, but considering the unreliability and high costs, they did not yield. As a result, though gene editing was a validated technology, it did not realize its potential because programmable nucleases were challenging to engineer.
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The scientific finding of CRISPR-Cas9 provided an ideal remedy. Rather than attempting to re-invent the wheel, it tried harnessing computable nucleases initially naturally modelled over the evolution period. While bacteria employed CRISPR-Cas9 to induce DNA intervals into viral genomics for prevention of infections, an alternative idea was using CRISPR-Cas9 to launch a DNA break in eukaryotic genomes, thus modifying the gene. The attribute enabling CRISPR-Cas9 effectiveness in adjustable immunity, including the aptitude to guide DNA targets making use of RNA lead, had the potential to change a scientist’s capacity to apply nucleases to alter DNA targets and spot them for repairs. CRISPR-Cas9 was in 2012 found to contain crucial constituents of gene editing and especially being discovered to be successful in mouse and human cells (Cong et al., 2013). In a short time, scientists developed genetically-edited mice with CRISPR, and later was rapid succession in rats, wheat and primates, and an increasing lineup of other species.
Alongside the efflux in organisms with genomes homogeneously modifiable with CRISPR, 2013 recorded an influx in different DNA modifications accomplishable through CRISPR automation (Gupta & Musunuru, 2014). In addition to fastening minor errors in the genome, like types of mutations causing hereditary defects, CRISPR can be leveraged to either inactivate or delete genes, invert or insert genes, and introduce changes to many genes concurrently. A notable distinct area of application during this period included the adoption of non-cutting CRISPR-Cas9 version, whereby the aim was to ferry more payloads to specific genes to turn genes either on or off, up or down. Through altering gene expression without altering the DNA sequence, a scientist can start controlling the same molecular cues which instruct cells to turn into body tissues, all utilizing one underlying genetic code.
Current Applications and Future Developments
Plant breeders are impressed by the possibility of engineering new characteristics into main cash crops with a safer and more effective method compared to the random mutagenesis method used in the 20th century. The technology is also less invasive in comparison to the techniques used to develop genetically modified organisms (GMOs). While there are many protests against biotechnology products that people eat, some efforts can address global hunger, nutritional deficiency, as well as farming challenges facilitated by future impacts of the changing climate thus permissible. Among food producers, customized DNA mutations can multiply muscle content, lessen diseases while offering solutions to issues previously handled through ruthless methods. For instance, the Recombinetics company introduced a remarkable achievement of genetically dehorning cattle (Sternberg, 2017), which is a more humane method compared to the cruel practice of dehorning by cauterization.
There are applications of CRISPR that seem to cling on science fiction. Instead of harnessing gene-editing technology to come up with new organisms, some researchers aim at doing the opposite and leveraging gene editing to bring back an animal that once existed, for instance, the wooly mammoth. Through the use of well-preserved frozen tissue samples, geneticists have successfully deciphered the linear sequence of the wooly mammoth genome, allowing a straight comparison to the genome of elephant, a close relative (Relagado, 2016). Currently, some scientists are using CRISPR to change specific genes in elephant cells into the wooly mammoth counterparts, while giving priority to genes implicated in functions like fat tissue production and skin development. More genetic engineering efforts have been put in place to yield more de-extinction efforts in species like great auks and passenger pigeons.
Another application of CRISPR in animals includes the potentially revolutionary technology referred to as the gene drive (Regalado, 2016). It has intricate scientific details dealing with a knowledgeable workaround of fundamental laws of inheritance initially discovered by Gregor Mendel on his pea plants experiment. CRISPR-based gene drives permit bioengineers to break these laws and successfully drive new genes into wild animal populace at high speed with their associated characteristics. An even more convincing real example is the mosquito. With CRISPR, it is possible to produce genetically modified mosquitoes, engineered in a way that they cannot transmit malaria anymore. This feat has been performed in a contained lab environment, and there are undergoing discussions concerning whether the technology is safe for field trials. If it were possible to eradicate mosquito-borne illnesses and save many lies annually, then it is justifiable taking the risk.
In humans, there are new tools developed to control genetic diseases. Scientists are using CRISPR-Cas9 to edit the human genome and knock out genetic diseases, including hypertrophic cardiomyopathy. They also emphasize on utilizing it on mutations causing Huntington’s disease and cystic fibrosis, while thinking of trying it on BRCA-1 and two mutations related to breast and ovarian cancers (Gupta & Musunuru, 2014). Besides, research shows that CRISPR has the potential to knock out HIV infections from T cells. Unfortunately, this has not yet been tried but only tested on cells in the laboratory. There is the risk of enzymes misfiring and editing DNA in unexpected areas leading human cells to cause cancer or create new illnesses. While this offers a beautiful stance for future development, more work is to be done on delivering the editing molecules to particular cells for precise gene editing.
Ethical Controversy
In 2015, a Chinese group reported the initial application of CRISPRCas9 to human embryos. However, this development, and the decreasing technology costs, trigger the debate on whether the technology should be in use. One critical issue is the philosophical dilemma of embryo editing, centering on how far CRISPR-Cas9 must be adopted to change germ-line cells (egg and sperm), responsible for handing over genes to the next generation (Sternberg, 2017). It may take many more years before the technology is successfully used in the creation of designer babies, but already public debates have started concerning this issue. Some scientists, including few who pioneered the invention of CRISPR-Cas9, call for the prohibition in its utilization in germ-line cells.
Another critical issue is concerning safety. The technology is still in the infancy stages, and there is limited knowledge concerning the genome. Some scientists are wary that this technology needs more work to enhance accuracy and ensure changes introduced in a particular part of the genome do not bring more changes elsewhere, which may cause unforeseen repercussions (Hsu, Lander & Zhang, 2014). This is primarily an essential issue in the use of a technological application aimed towards human health. Besides, once an organism, like a plant or insect, undergoes modification, they are indistinguishable from the wild type, hence could endanger biodiversity when released to the environment.
In conclusion, considering the popularity and availability of CRISPR, it domineers projections involving genome editing. One can expect CRISPR-based systems to improve continually, thus introducing upgraded gRNAs with better specificity. In years to come, CRISPR will affect the food that people consume, medicines they take, and undoubtedly even the understanding of the CRISPR technology will itself evolve. As seen, CRISPR-Cas9 is one of the remarkable molecular machines developed by microbes to counteract interminable strikes from alien pathogens, and researchers continually invent innovative applications of this biological value accretion. Never would anyone have thought that scientific curiosity and scholarly investigation would unveil such an optimistic scope of biotechnological exploration.
References
- Chandrasegaran, S., & Carroll, D. (2016). Origins of programmable nucleases for genome engineering. Journal of molecular biology, 428(5), 963-989.
- Cong, L., Ran, F. A., Cox, D., Lin, S., Barretto, R., Habib, N., ... & Zhang, F. (2013). Multiplex genome engineering using CRISPR/Cas systems. Science, 339(6121), 819-823.
- Gupta, R. M., & Musunuru, K. (2014). Expanding the genetic editing tool kit: ZFNs, TALENs, and CRISPR-Cas9. The Journal of clinical investigation, 124(10), 4154-4161.
- Hsu, P. D., Lander, E. S., & Zhang, F. (2014). Development and applications of CRISPR-Cas9 for genome engineering. Cell, 157(6), 1262-1278.
- Regalado, A. (2016). The extinction invention. MIT Technology Review, 13, 2016.
- Sternberg, S. (2017). The Biological Breakthrough of CRISPR-Based Gene Editing. Retrieved from https://www.bbvaopenmind.com/en/articles/the-biological-breakthrough-of-crispr-based-gene-editing/
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