Scissoring the DNA: On Chemistry Nobel
Mains: General Studies-III: Technology, Economic Development, Bio diversity, Environment, Security and Disaster Management
Emmanuelle Charpentier of France and Jennifer Doudna of the U.S. won the Nobel Chemistry Prize for the gene-editing technique known as the CRISPR-Cas9 DNA snipping scissors. But most importantly, this year’s Prize for chemistry has created history by honouring an all-woman team.
What is CRISPR and Genome Editing?
- Genome editing (also called gene editing) is a group of technologies that give scientists the ability to change an organism’s DNA.
- These technologies allow genetic material to be added, removed, or altered at particular locations in the genome.
- Genome editing is of great interest in the prevention and treatment of human diseases.
- CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats.
- Crispr is repeating sequences of genetic code and serve as part of the bacterial immune system, defending against invading viruses.
- CRISPR is a genome-editing technology to diagnose diseases.
- CRISPRs are specialized stretches of DNA.
- The protein Cas9 (or “CRISPR-associated”) is an enzyme that acts like a pair of molecular scissors, capable of cutting strands of DNA.
- CRISPR technology was adapted from the natural defence mechanisms of bacteria and archaea (the domain of single-celled microorganisms).
- These organisms use CRISPR-derived RNA and various Cas proteins, including Cas9, to foil attacks by viruses and other foreign bodies. They do so primarily by chopping up and destroying the DNA of a foreign invader.
To “rewrite the code of life”:
- It all started when Dr. Charpentier discovered an RNA molecule that is part of bacteria’s ancient immune system — CRISPR-Cas — wherein clustered repeated sequences produced by bacteria can remember and destroy viruses by cleaving their DNA.
- Teaming with Dr. Doudna, she recreated the bacteria’s genetic scissors in a test tube and simplified the tool to make it easier to programme the system to precisely cut specific sites of interest in any DNA, including humans.
- While the tool is most often used to make a cut in the DNA, newer approaches are being attempted to add or make minor changes to the DNA.
Vast window of Oppurtunity:
- The path from discovery to prize has taken less than a decade — a relatively short period by Nobel standards.
- Most research on genome editing is done to understand diseases using cells and animal models.
- Gene editing is being explored in research on a wide variety of diseases, including single-gene disorders such as cystic fibrosis, haemophilia, and sickle cell disease.
- It has also given hope for the treatment and prevention of more complex diseases, such as cancer, heart disease, mental illness, and human immunodeficiency virus (HIV) infection.
- In the last six years, the tool has enabled scientists to edit human DNA in a dish
- Early-stage clinical trials are being attempted to use the tool to treat a few diseases, including inherited disorders/diseases and some types of cancer.
CRISPR: What are the ethical concerns?
- Although Crispr had widely been tipped to win the Chemistry Nobel prize, there has also been concern about possible misuse of the technology, for example, to create made-to-order ‘designer babies’.
- in 2016 China began the first human clinical trial to treat an aggressive form of lung cancer by introducing cells that contain genes edited using CRISPR-Cas9, the use of the tool has so far been limited to curing genetic diseases in animal models.
- Last year, a Chinese researcher used the tool to modify a particular gene in the embryo to make babies immune to HIV infection, which led to international furore.
- Though no guidelines have been drawn up so far, there is a general consensus in the scientific and ethics communities that the gene-editing technique should not be used clinically on embryos.
- The gene-editing tool has taken “life sciences into a new epoch”
- Unlike in the case of humans, the tool is being extensively used in agriculture.
- It is being tried out in agriculture primarily to increase plant yield, quality, disease resistance, herbicide resistance and domestication of wild species.
- The huge potential to edit genes using this tool has been used to create a large number of crop varieties with improved agronomic performance;
- It has also brought in sweeping changes to breeding technologies.