While looking into the forest of microbes that live inside us, researchers have stumbled upon what appears to be an entirely new class of virus-like organisms.
“It's crazy,” says Mark Pifer, a cell biologist at the University of North Carolina who was not involved in the study. Tell Elizabeth Pennisi in Science Magazine. “The more we look, the crazier things we see.”
These mysterious bits of genetic material have no detectable sequences or even known structural similarities to any other biological agents.
So Stanford University biologist Ivan Zhilodev and his colleagues say their strange discovery may not be viruses at all, but rather an entirely new set of entities that may help bridge the ancient gap between the simplest genetic molecules and more complex viruses.
“Opelaxes include a class of diverse RNAs that have colonized human and global microbes and have not been observed.” Writing on preprint paper.
Named after the highly symmetrical, rod-like structures made up of twisted lengths of ribonucleic acid (RNA), the genetic sequence of stelae is only about 1,000 letters (nucleotides) in size. In fact, this brevity is likely one of the reasons we failed to notice them earlier.
In a study that has not yet been peer-reviewed, Zhilodev and his team combed through 5.4 million datasets of published genetic sequences and identified nearly 30,000 different sequences. It appeared in about 10% of the human microbes the team examined.
In one data set, obelisks appeared in 50% of patients' oral samples. Furthermore, different types of obelisks seem to be located in different areas of our bodies.
“[This] “Supports the idea that the obelisks may include colonizers of the aforementioned human microbes.” He explains.
They were able to isolate one type of host cell from our microbiome, namely bacteria Streptococcus sanguiniss – Common human mouth microbe. The obelisk in these microbes contains a loop that is 1,137 nucleotides long.
“Although we don't know the 'hosts' of the other obelisks,” He writes Zhilodev and colleagues. “It is reasonable to assume that at least some part is in bacteria.”
Regardless of the source of the obelisks, they all appear to include symbols for a new class of protein that researchers have dubbed oblins.
The instructions for building these proteins appear to take up at least half of the Obelisks' genetic material. Since these proteins are very similar in all obelisks, researchers suspect that they may be involved in the entity's replication process.
This ability to encode proteins makes them different from other known RNA loops called viroids, but they also do not appear to have the genes needed to make the protein envelopes that RNA viruses (including COVID-19) live in when they are… outside the cells. .
They are also much larger than other genetic molecules that coexist inside cells, from plants to bacteria, which are called… Plasmidswhich is commonly composed of DNA.
However, Zhilodev and his team were unable to identify any effect of the obelisks on their bacterial hosts, or a means by which they could spread between cells.
“These elements may not be viral in nature and may more closely resemble RNA plasmids.” We conclude.
This research has been submitted to pre-print service. com.bioRxiv.
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