Obelisks: An Unusual Life Form

Context: 

Recently, Scientists at Stanford University identified a new form of life ‘obelisks’ lying between viruses and viroids from bacteria present in the human gut.

• The discovery is based on the data obtained from Next-generation sequencing (NGS) (which allows researchers to determine genome sequences parallelly, in bits and pieces from different organisms.)

About Obelisks

• These are Viruses like  biological entities hiding inside the human mouth and gut.
• They represent their class of distinct organisms between Viruses & Viroids.
• Structure: 
  • These entities organise themselves into Rod-like structures by their twisted length of RNA
• Genetic  Makeup: 
  • They have only around 1,000 characters (nucleotides) in size.
  • Like viroids, obelisks have a circular single-stranded RNA genome and no protein coat.
  • But, like viruses, their genomes contain genes predicted to code for proteins. 
  • They encode a single major protein known as ‘obulin’.

Obelisks vs Viruses vs Viroids

• Viruses: 

  • Viruses cannot replicate without a host, they infect a host cell, use the cell’s machinery to make more copies of themselves, and then infect a new cell to repeat the cycle.

• Viroids: 

• • These are tiny scraps of genetic material of RNA that serve no function apart from propagating themselves.
  • RNA of viroids does not code for any protein. 
  • They don’t have a protective shell to encase their genome. 
• Obelisks fall somewhere between viruses and viroids.
  • Obelisk RNA is much longer than viroids and appears to code for two proteins, neither of which bear any similarity to any known protein from any other life form.

Uncertainty About Obelisks

• The evolutionary and ecological roles of parasites or beneficial organisms are yet to be confirmed. 
• Hosts might have developed defence mechanisms against obelisks or could actively engage them for advantages. 
• Any alterations caused by obelisks to the human microbiome could impact human health possibly it can offer therapeutic prospects.

News Source: The Hindu

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