Late last year, it was reported that scientists had discovered new forms of life inside human bodies. They don’t match anything biology has classified.
A new class of RNA molecules
was discovered inside bacteria that lives in the human body. They are circular
genetic structures called obelisks. They differ from known viruses and
bacteria. They appear to represent an unclassified category of RNA.
The discovery came from
an analysis of genetic material obtained from microbial communities inside
humans. Obelisks may be present across global populations. But their
exact function is unclear.
These RNA entities are
simple. They don’t encode proteins. They don’t form protective protein shells.
They consist of short loops of RNA that replicate, although how remains a
mystery.
More than 3,000 types
of obelisks have been identified using computational tools designed to detect
circular RNA structures in large genomic libraries. Researchers detected
closed-loop RNA structures that lack protein-coding regions. As such, the
molecules resemble viroids, which are also non-coding, circular RNAs.
However, viroids infect plants, but obelisks are only found in human-associated
bacteria.
Many of the obelisks
are embedded in bacterial genomes, which suggests they may have adapted to
specific bacterial hosts. No immediate health effects have been linked to
obelisks, but their residence in bacteria that support digestion, immunity, and
other function point to future research on the matter.
Obelisks don’t conform
to definitions of viruses, plasmids, or other mobile genetic elements. They
fall outside microbial categories.
The implications extend
into evolutionary biology, particularly in the origins of RNA-based life. Some
theories suggest early life may have relied solely on self-replicating RNA.
Obelisks could offer insight into these early evolutionary stages.
Obelisks do exhibit
genetic diversity. Different variants appear in specific regions of the body.
This may reflect host-specific adaptations. It is unknown if they have any
regulatory or ecological function in the microbiome.
There is scientific
interest in non-coding and circular RNAs, which play roles in gene regulation
and cellular function in plants and animals. Obelisks are different in that
they seem to operate independently, with no participation in protein synthesis
or cellular regulation.
The discovery shows
that modern metagenomic-sequencing can detect molecular entities that don’t fit
into established classifications.
Scientists expect
further discoveries of novel RNA forms with unknown roles. It is not known if
obelisks are ancient relics or modern molecular parasites. Research continues.
https://www.msn.com/en-us/health/medical/scientists-discover-new-forms-of-life-inside-human-bodies-that-don-t-match-anything-biology-has-classified/ar-AA1T7ARd?ocid=hpmsn&cvid=695189ccf8ea491b9920af677646366e&ei=56
