What are ‘Obelisks’, the New Virus-like Life-forms?

A new genetic entity dubbed ‘obelisks’ has recently been discovered in abundant numbers inside bacteria inhabiting the human gut and mouth. This never-before-seen biological construct displays unique characteristics unlike other known viruses or cell types, prompting researchers to classify obelisks as a third fundamental domain that could help better understand microbial ecology in the human body.

Groundbreaking Finding

In a first-of-its-kind study published in the journal Cell, researchers from San Diego-based biotech company Locanabio analysed RNA sequence datasets from thousands of bacterial samples which are part of the human microbiome – the collection of microbes residing in our gut, skin, organs etc. that regulate various bodily functions.

Out of 5.4 million bacterial RNA sequences screened by the team, they discovered strange tower-shaped genetic elements present in over 220,000 sequences sourced from gut bacteria. Further investigation uncovered a staggering 29,959 distinct varieties of these ‘obelisks’ inside human oral microbes as well.

Defining Traits of Obelisks

Obelisks comprise of RNA and proteins that allow them to self-replicate inside bacterial cells. Though they share similarities with known viral entities, obelisks possess certain core traits that make them utterly unique.

Firstly, unlike viral sequences which exhibit diversity, obelisk genes perform same functions across different bacterial strains. Secondly, obelisks can propagate vertically from parent to offspring cells along with the bacteria they inhabit.

They also integrate loosely into the bacterial genome rather than disrupting normal cell mechanisms. Their stationary vertical transfer and genomic integration without causing cell damage together set obelisks apart from parasitic viruses.

A New Addition to the Biology Textbooks

The researchers make a strong case for classifying these distinctive genetic passengers as a third fundamental branching in the tree of life – alongside the established two domains of viruses and viroids.

As per the Scientists, they have their own machinery to replicate themselves, so they’re not like viruses or viroids which need the machinery of their hosts in order to reproduce.

Ubiquity Across Geographies

An astounding revelation by the scientists is the ubiquity of obelisks in human microbiomes across diverse ethnicities and continents. Samples studied included gut bacteria from not just U.S. subjects but also diverse countries across Asia, Africa, South America and Europe. Oral microbiome datasets spanned people from seven continents.

But despite geographical differences, obelisks demonstrated their widespread presence in both gut and mouth bacteria within human hosts globally. This underscores how they have become an integral component of microbiomes universally.

Implications for Human Health

Uncovering this previously invisible genetic entity opens up new avenues to advance our understanding of host-microbiome symbiosis and how it shapes human health.

While the obelisks function remains unclear, researchers hypothesize they may interact with host immunity to potentially protect bacteria against antibiotics and viruses. Further studies in this area can reveal exciting insights into manipulating microbe-host dynamics.

Additionally, cataloguing obelisk diversity within healthy and diseased microbiome types could inform about their disease relevance. Edwards’ team has already found reduced obelisk populations in bacteria extracted from IBD patients compared to healthy gut flora.

The discovery establishes obelisks as a microbe’s microbe that form a third leg propping up the epitome of complex living systems i.e. the human microbiome. Unpeeling their mysteries promises to open new frontiers in biology.


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