Scientists have discovered a ‘crazy’ new life form lurking in our bodies.
They found entirely new virus-like entities called ‘obelisks’, which are circular pieces of genetic material that contain one or two genes and organize themselves into a rod-like shape.
Obelisks are found in half the world’s population, but were only discovered when researchers looked for patterns that did not match known organisms in genetic libraries.
They colonize the bacteria in people’s mouths and intestines and live in their host for about a year, but scientists don’t know how they spread.
Obelisks have genomes of RNA loops that resemble viroids, which are viruses that infect plants, leaving experts wondering why they were found in human-associated bacteria.
“It’s crazy,” says Mark Peifer, a cell and developmental biologist who was not involved in the study. Science. “The more we look, the more crazy things we see.”
It’s unclear whether obelisks are harmful or helpful, but the team suggested they “could exist as stealthy evolutionary passengers.”
Scientists also said that these small, primitive entities may have played a crucial role in shaping the biodiversity that exists on Earth today, because they could infect organisms of many different species throughout their evolution.
Scientists have discovered a new life form called ‘obelisks’ lurking in the bacteria that live in our intestines and mouths (STOCK)
Scientists aren’t yet sure whether these newly discovered life forms can make people sick, but there is one type of viroid that can: Hepatitis D.
Obelisks, viroids, and viruses are all technically non-living organisms that depend on a host for survival. They do not eat, regenerate or copulate.
Yet some researchers believe that viroids and their relatives – perhaps also obelisks – represent the oldest ‘life forms’ on Earth.
The research team, led by Stanford biochemist Ivan Zheludev, discovered the obelisks by sifting through data from an RNA database containing thousands of sequences collected from human mouths, intestines and other sources.
They analyzed this data to look for single-stranded circular RNA molecules that did not match any known viroid sequences and did not code for proteins.
Their analysis revealed 30,000 different types of obelisk. Their genomes were previously overlooked because they are so different from any life forms previously found and documented.
But the findings have been published in the journal Cellindicate that obelisks are anything but rare.
Researchers discovered that half of the world’s population carries obelisks in their mouths, while just under seven percent carry them in their bellies.
Further research will be needed to fully understand how common they are.
The research team discovered the obelisks by sifting through data from an RNA database that contains thousands of sequences collected from human mouths, intestines and other sources.
The researchers believe that these creatures colonize bacterial cells in order to multiply, similar to the way a virus infects a host and then replicates within it.
The type of obelisk varied depending on what part of the body they were found in and what human sample they came from.
Long-term analysis suggested that a single obelisk type can live in a human host for about a year.
The researchers believe that these creatures colonize bacterial cells in order to multiply, similar to the way a virus infects a host and then replicates within it.
They found evidence for this host-pathogen relationship in Streptococcus sanguinis, a common bacterial component of dental plaque. This microbe harbors a specific type of obelisk.
This is important because this bacterial species can be easily grown in the laboratory, allowing future studies to understand how obelisks survive and multiply in microbial cells.
All obelisks discovered so far encode a key protein known as obulin, and many obelisks also encode a second, smaller form of this protein.
Obulins are completely different from any other known proteins, and scientists are still unsure what purpose they serve or how they function.
At this point, scientists can only speculate about the evolutionary and ecological role obelisks play.
It is possible that they are parasitic and harmful to their host cells, but they can also be beneficial or completely benign.
If future studies show that obelisks have a significant impact on the health or functionality of the human microbiome, it would be an important discovery for human health, experts say.