CRISPR – Sophisticated Gene Editing Tool

The Finding Stories Of CRISPR

A group of researchers from Japan, Ishino et al., reported in  1987 the finding of the unknown arrangement (sequences) which infiltrated among the DNA of Escherichia coli, which genetic material is not property of E. coli. However, Ishino et. al does not do the characterization of the nature of the genetic found. E. coli is normally found in the large intestine of human or animals that also play a role in maintaining digestive health.  In other part of the world,  in Costa Blanca, Spain, the arrangement of a DNA sequence that is not recognized in Haloferax mediterranei  in 1989 – a bacteria lives in the environment of high levels of salt, was observed by Francisco Mojica which led him to research deeper with the thought that the presence of genetic material that is not recognized is surely indicated an important function on the prokaryotic organisms (organisms without cell membranes[8]).

Similar replication structure was later found also on other types of bacteria, but with different arrangements, such as in Mycobacterium tuberculosis, Clostridium difficile and a host of bacteria Yersinia pestis plag, which these bacteria are caused disease in human. The phenomenon of foreign genetic material replication on the order of RNA, which is only found in Archaea and bacteria is then called a Clustered Regularly Interspaced Palindromic Repeats (CRISPR). The term appears in the research conducted by Jansen et al., 2002; Mojica & Garrett, 2012. Advanced research conducted in 2005 by Mojica suggested that CRISPR certainly contains a number of biological code which serves as a form of adaptation of the immune system that protects the Archaea (prokaryotic organisms that live in extreme habitats) and bacteria from virus attacks. In 2007, the functions of CRISPR as the immune system to fight off the virus infection is evidenced by Barrangou et al. In the years of published writings about this CRISPR function, another researches in similar areas also complete findings of CRISPR, as research conducted by Gilles Vergnaud in France in the field of forensic microbiology for developing a method for retreating sources of genetic causes of diseases on the basis of the difference between a number of strains of pathogens, and also a research in Russia by Bolotin Alexander which raised the issue of speculation that CRISPR  is a form of immunity [8].

Brief history, studies by a number of researchers in different parts of the Earth in a variety of molecular biology have developed adaptive immune system of these bacteria as a DNA tool editor. In fact, what does CRISPR do?. CRISPR itself is the term given to a piece of RNA molecules containing the bearer of information. The information stored in this CRISPR are copies of the genetic material of the virus infected a bacteria. RNA that contains CRISPR can then direct the enzyme CaS9, which also found inside the bacteria, to cut a piece of RNA that wanted to be changed (mutations) with the goal of keeping one’s DNA can be studied or be used for certain purpose by scientists[12], as the CRISPR is inseparable from the role of enzyme CaS9, then this system often referred with the term of CRISPR-CaS9. Today, the CRISPR is claimed by many  researchers in the world as an easy, fast, and cheap DNA editing tool [9]. Is it true ?.

Using CRISPR/CaS9 [11]

CRISPR Development

DNA editing tool called CRISPR is growing rapidly along with the ability of CRISPR to edit, re-order or even replace DNA for a specific purpose which claimed by many researchers as a tool which easier, faster and cheaper than other methods which researches ever used. The claims arose due to a few things. First, compared with the method of Zinc finger nucleases as gene editor costs around USD 5000, while the CRISPR costs only around USD 30 and relatively easy to use by the researchers. Secondly, previous technologies are only able to model or manipulate genes in mice and fruit flies, while the CRISPR allows to do editing/manipulation of genes to different kinds of other organisms [9].

Cas9 cut the DNA [2]

Baca juga:

In 2013, Cong et. al., utilizing CRISPR/Cas type II for studying endogenous cell division process (in human cells or animal)[3,9]. In the same year, 2013, CRISPR are used to help researchers in the study of the efficiency of the process of changing the genetic material/gene mutation (insertional) on protoplast in Arabidopsis (a plant model used to study genetics in dicotyledon plants), and a tobacco[5,9]. Besides its wide application in plants, animals, even human cells, the utilization of CRISPR is also used by a researcher to study a type of fungal pathogens that cause deadly infections in mucous membranes or internal organs in human, i.e., Candida albicans, which its DNA was observed, manipulated and studied its pathogenesis (how a disease attack and grow in the body of the organism)[13]. CRISPR ability to edit and manipulate genetic material on the various types and levels of organisms made CRISPR is beyond editing tool and distinguished than the Zinc Finger Nuclease (ZFN) or TALENs. The following graph shows the interest of researchers towards CRISPR technology shown in the rise of publications using  CRISPR technology beats the number of publications of zinc fingers or TALENs.

Figure 1. Comparison of research publications on a variety of DNA editing tools [9]
 

CRISPR and the ethics ?

The ability to edit the CRISPR technology (changing) the DNA, then raises the ethical debate among academics and scientists. Fears of a potential outbreak of the imbalance of the ecosystem, for example if the technology is used to manipulate mosquitoes cause malaria in human, Anopheles, or even create these extinct, leading a concern as killing or to eliminate a certain biological capabilities on a single species, then it can also potentially eliminates the control of predators or may interfere with the process of pollination of certain plants that utilize the help of this mosquito [10]. Other concerns emerged in 2015, where a group of researchers from China do gene modification on β-Thalassemia in human embryo cells cause abnormalities in the blood, the modifications then causing a number of embryos to see death, so the research was stopped at an early stage [4]. Discussion and debate related ethical limits in CRISPR is more crowded. It is interesting to watch Ellen Jorgensen in TEDTalk, she says that the use of CRISPR technology, which allows the scientists to make changes on genes in almost all species must bring good to mankind and all living beings on Earth. For Jorgensen, this technology can be used to study on how a DNA works or learn on how an organism can infect human, so prevention and handling on a disease can be overcome by means of precise and correct way [6].

Guest lectures Ellen Jorgensen on TEDTalks CRISPR about technology [6]

Sources:

[1] As-Shiddiq, Billy. Mycobacterium Tuberculosis Disease. http://tuberkulosis.autoimuncare.com/penyakit-mycobacterium-tuberculosis/

[2] Biohack Info. CRISPR DNA Editing in Real Time. https://www.youtube.com/watch?v=gvTbIdKFJMM

[3] Cong, et al. Multiplex Genome Engineering Using CRISPR/Cas Systems. 10.1126/1231143 science.

[4] David Cyranoski & Reardon, Sara.  Chinese scientist genetically modify human embryos. Nature doi: 10.1038/2015.17378 nature.

[5] Jian-Feng, et al. Multiplex and homologous recombination-mediated plant genome editing via guide RNA/Cas 9. DOI: 10.1038/nbt. 2654

[6] Jorgensen, Ellen. What You Need to Know About CRISPR. TED. https://www.youtube.com/watch?v=1BXYSGepx7Q

[7] Kumala, Widyasari. Clostridium difficile: causes diarrhea and colitis pseudomembranosa, due to the irrational consumption of antibiotics. J Kedokter Of Trisakti. http://libprint.trisakti.ac.id/163/1/2004-Kumala.pdf

[8] Lander, Eric S. The Heroes of CRISPR. http://dx.doi.org/10.1016/j.cell.2015.12.041

[9] Ledford, Heidi. CRISPR, the disruptor. Nature 522, 20 – 24 (04 June 2015) doi: 10.1038/522020a

[10] Ledfor, Heidi & Callaway, Ewen. ‘ Drive ‘ Gene engineered mosquitoes to fight malaria. Nature doi: 10.1038/2015.18858 nature.

[11] McGovern Institute for Brain Research at MIT. Genome Editing with CRISPR-Cas. https://www.youtube.com/watch?v=2pp17E4E-O8

[12] Hesman Saey, Tina. Explainer How CRISPR Works. https://www.sciencenewsforstudents.org/article/explainer-how-crispr-works

[13] Valmik k. Vyas, et al. A Candida albicans CRISPR system permits genetic engineering of essential genes and gene families. DOI: 10.1126/sciadv. 1500248  

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