Adrianna Tan

Wake up babe, new form of life just dropped

https://www.biorxiv.org/content/10.1101/2024.01.20.576352v1

#Science #Obelisks

Viroid-like colonists of human microbiomes

Here, we describe the “Obelisks,” a previously unrecognised class of viroid-like elements that we first identified in human gut metatranscriptomic data. “Obelisks” share several properties: (i) apparently circular RNA ∼1kb genome assemblies, (ii) predicted rod-like secondary structures encompassing the entire genome, and (iii) open reading frames coding for a novel protein superfamily, which we call the “Oblins”. We find that Obelisks form their own distinct phylogenetic group with no detectable sequence or structural similarity to known biological agents. Further, Obelisks are prevalent in tested human microbiome metatranscriptomes with representatives detected in ∼7% of analysed stool metatranscriptomes (29/440) and in ∼50% of analysed oral metatranscriptomes (17/32). Obelisk compositions appear to differ between the anatomic sites and are capable of persisting in individuals, with continued presence over >300 days observed in one case. Large scale searches identified 29,959 Obelisks (clustered at 90% nucleotide identity), with examples from all seven continents and in diverse ecological niches. From this search, a subset of Obelisks are identified to code for Obelisk-specific variants of the hammerhead type-III self-cleaving ribozyme. Lastly, we identified one case of a bacterial species ( Streptococcus sanguinis ) in which a subset of defined laboratory strains harboured a specific Obelisk RNA population. As such, Obelisks comprise a class of diverse RNAs that have colonised, and gone unnoticed in, human, and global microbiomes. ### Competing Interest Statement The authors have declared no competing interest.

bioRxiv
Jan 18 at 6:50amWeb
Show threadAdrianna TanJan 18
https://en.wikipedia.org/wiki/Obelisk_(biology)
Obelisk (biology) - Wikipedia

Show threadAdrianna TanJan 18

More info

https://mathstodon.xyz/@johncarlosbaez/113833717125234048

John Carlos Baez (@johncarlosbaez@mathstodon.xyz)

Attached: 1 image Wow! Biologists seem to have discovered an entirely new kind of life form. They're called 'obelisks', and you probably have some in you. They were discovered in 2024 - not by somebody actually seeing one, but by analyzing huge amounts of genetic data from the human gut. This search found 29,959 new RNA sequences, completely different from any known. Thus, we don't know where these things fit into the tree of life! Biologists found them when they were trying to solve a puzzle. Even smaller than viruses, there exist 'viroids' that are just loops of RNA that cleverly manage to reproduce using the machinery of the cell they infect. Viruses have a protein coat. Viroids are just bare RNA - it doesn't even code for any proteins! But all known viroids only infect plants. The first one found causes a disease in potatoes; another causes a disease in avocados, and so on. This raised the puzzle: why aren't there viroids that infect bacteria, or animals? Now perhaps we've found them! But not quite: while obelisks may work in a similar way, they seem genetically unrelated. Also, their RNA seems to code for two proteins. Given how little we know about this stuff, I think some caution is in order. Still, this is really cool. Do any of you biologists out there know any research going on now to learn more? The original paper is free to read on the bioRxiv: • Viroid-like colonists of human microbiomes, https://www.biorxiv.org/content/10.1101/2024.01.20.576352v1.full I see just one other paper, about an automated system for detecting obelisks: • Tormentor: An obelisk prediction and annotation pipeline, https://www.biorxiv.org/content/10.1101/2024.05.30.596730v1.full There's also a budding Wikipedia article on obelisks: https://en.wikipedia.org/wiki/Obelisk_(biology) Hat-tip to @metaweta.

Mathstodon
Show threadDaniel DurransJan 18
@skinnylatte When I heard about these on a podcast recently (Infinite Monkey Cage podcast I think it was) the name evokes a very specific mental image for me. It's the primates gathered around a black rectangle from 2001 A Space Odyssey.
Show threadJeremy KahnJan 18

@dan @skinnylatte

I thought of @2001 too

Show threadBoogle™Jan 18

@trochee @dan @skinnylatte @2001

I like to imagine a tiny tiny Cenobites Leviathan from Hellraiser

Show threadDaniel DurransJan 18
@TheBreadmonkey @trochee @skinnylatte @2001 that would explain a lot.
Show threadgreemJan 18
@dan @skinnylatte someone needs to find out if they have a specific resonant frequency. If they do, and it matches, then we're in deeper doodoo than it appears!
Show threadGreg HaasJan 18
@dan @skinnylatte That’s interesting. My first mental image was of the cartoon character, Obelix.
Show threadJeremy KahnJan 18
@skinnylatte wild!
Show threadJoan't Stop Me Now 🏳️‍🌈🏳️‍⚧️😷Jan 18
@skinnylatte "Trust your gut," they said. Well. Never again!
Show threadSean BalaJan 18
@skinnylatte O_O
Show threadBoogle™Jan 18

@skinnylatte

I am loving 'Oblins'

Show threadADHDeanJan 18
@TheBreadmonkey Turns out we’re all going Oblin Mode @skinnylatte
Show threadinternetsdairyJan 18
@TheBreadmonkey @skinnylatte 'a novel protein superfamily, which we call the “Oblins”' next on CBeebies