Why in news?
- A team from National Centre for Biological Sciences, Bengaluru, has developed a diagnostic system to detect the presence of Merkel cell polyomavirus in Merkel cell carcinoma tumours.
- The researchers have developed a test using the CRISPR-CAS12 technology.
- This is an important development, both, from the point of view of diagnostics and giving a prognosis for the condition.
What is Merkel Cell Carcinoma?
- Merkel cell carcinoma is a rare and aggressive type of skin cancer.
- Merkel cell carcinoma is associated with old age, excessive exposure to ultraviolet light and a weak immune system.
What is CRISPR-CAS12?
- CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea.
- These sequences are derived from DNA fragments of bacteriophages that had previously infected the prokaryote.
- They are used to detect and destroy DNA from similar bacteriophages during subsequent infections.
- Hence these sequences play a key role in the antiviral (i.e. anti-phage) defense system of prokaryotes.
Cas12 and Cas9
- The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas (CRISPR-associated proteins) is a prokaryotic adaptive immune system that is represented in most archaea and many bacteria.
- In 2015, the nuclease Cas12a was characterized in the CRISPR/Cpf1 system of the bacterium Francisella novicida.
- Cas12a showed several key differences from Cas9 including: causing a ‘staggered’ cut in double stranded DNA as opposed to the ‘blunt’ cut produced by Cas9 Cas12a. This and other differences provide Cas12 some advantages over Cas9.