"The Discovery of Genome Editing Tool: CRISPR-Cas9"

Would you edit your traits and change your appearance, personality and even prevent diseases if you could? Genes consist of DNA carry the information that determines your traits, such as how an organism survives, its appearance, and how it behaves. They influence each individual's behavioral and psychological characteristics, including intellectual ability, personality, and even risk for mental and physical illness. For decades, humans have thought that it was inevitable to prevent genetically caused diseases as well as change the traits of human after their genes have been formed. This was, until a new genome editing tool, CRISPR-Cas9 got discovered. 

The first clue of this existence came in 1987 when team of Japanese scientists in Osaka Unveristy, noticed a strange pattern of DNA sequences in a gene from Escherichia coli bacteria.  It appeared that the gene had five short repeating segments of DNA separated by short non-repeating 'spacer' DNA sequences. It was a new patter microbiologists had never seen before. By the end of 1990s, with the help of new improvements to DNA sequencing, they had discovered that this pattern was prevalent in many different microbe species. This pattern was so common that eventually it was given with its own name, ‘clustered regularly inter-spaced short palindromic repeats’ which stands for CRISPR for short. In 2002 this second set of sequence was called ‘Cas genes’, an abbreviation for CRISPR-associated genes which appeared to code for enzymes that cut DNA. By 2005 with further research, the scientific teams had worked out that the ‘spacer’ sequences between CRISP sequences shared similarities with the DNA of viruses and they hypothesised that it could be a tool for natural defense against bacteria. Accompanied by the knowledge of how the CRISPR-Cas 9 system worked, in 2012 Emmanuelle Charpentier and Jennifer Doudna were the first to publish a paper showing how to harness CRISPR-Cas9 system as a tool to cut DNA strand in a test tube, demonstrating precision and simplicity of the system in editing DNA, marking a significant eureka moment in history.

CRISPR-Cas9 functions as a pair of molecular scissors which precisely cut and modify DNA sequences. CRISPR is a part of the bacterial immune system that acts as a molecular memory which stores information about viruses that have attacked the bacteria before. There are two major classes of CRISPR-Cas9 system with six types and a number of subtypes. The two major classes are: the guide RNA, which matches the DNA sequence they want to edit, directing the Cas 9 protein to a specific area on the DNA sequence targeted for modification, and the Cas9 protein itself, which is an enzyme that acts as the molecular scissors cleaving the DNA. Once the DNA has been cut, the cell’s repair machinery tries to fix this, allowing scientists to introduce changes during this repair process which can include: adding, removing, or altering specific DNA sequences. CRISPR-Cas9 allows scientists to target a specific part of the DNA and either turn off certain genes, repair mutations, or introduce new genetic information. 

CRISPR technology has different potential applications across various fields such as medicine, agriculture and biotechnology. In medicine, scientists have said that this technology could treat certain types of cancer as well as genetic disease such as sickle cell anemia and cystic fibrosis. However, the impact of CRISPR-Cas9 isn’t only limited in the field of medicine. In agriculture, the ability to precisely modify crop DNA can bring a significant change in the industry. This tool will offer the opportunity to develop crops that are more resilient to pests, diseases and environmental stress which would therefore improve agricultural productivity and sustainability. Additionally, it has been applied in biotechnology for creating disease -resistant livestock and enhancing certain food traits.

In conclusion, eventhough CRISPR-Cas9 redefine boundaries of possibility, ethical considerations and regulatory frameworks are crucial as the power to edit the human genome brings about profound ethical dilemmas and potential misuse of this technology as many scientists have suggested. Discussions around the ethical implications and responsible use of CRISPR technology are essential for its responsible and beneficial applications.

Work Cited:

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Fischman, J. (2020). Nobel Prize in Chemistry Goes to Discovery of ‘Genetic Scissors’ Called CRISPR/Cas9. [online] Scientific American. Available at: https://www.scientificamerican.com/article/nobel-prize-in-chemistry-goes-to-discovery-of-genetic-scissors-called-crispr-cas911/.

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Ng, D. (2020). A Brief History of CRISPR-Cas9 Genome-Editing Tools. [online] Bitesize Bio. Available at: https://bitesizebio.com/47927/history-crispr/.

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Suresh, S. (2021). Beginner’s guide to CRISPR-Cas9-based gene editing. The Biochemist. doi:https://doi.org/10.1042/bio_2021_131.