Biology:Obelisk (life form)
An obelisk is a "viroid-like element" of a type first described in a January 2024 preprint, whose authors say that "Obelisks form their own distinct phylogenetic group",[1][2][3][4] as their RNA sequences, discovered by computer-aided metatranscriptomics, are not homologous with the genetic code of any other life form.[1]
With their relationship to other organisms being unknown, they are an example of the incertae sedis.
Distribution and pathology
Obelisks have been found in human stool samples, and inside specimens of Streptococcus sanguinis, a species of bacteria, taken from human mouths. Some human subjects harboured obelisks for more than 300 days. The initial study showed the presence of obelisks in about 7 percent of the stool samples, and about 50 percent of saliva samples, from individuals living on all continents.[1]
The effect of obelisks on human health, if any, is yet to be determined,[2] as are issues such as their life cycles, and what factors their replication depend on.[1]
Genetics and biochemistry
Other features of obelisks include circular RNA genome assemblies with around 1000 base pairs, rod-like secondary structures which encompass the entire genome. In contrast to viroids, their RNA is translated into proteins, tentatively called "oblins". The two proteins listed the preprint have been named Oblin-1 and Oblin-2.[1]
First structural predictions say that Oblin-1 can bind metal ions and thus could be involved in cellular signalling. Oblin-2 features a binding site which is typical for protein complexes; Oblin-2 could therefore bind to enzymes of its host cells.[2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 , Wikidata Q124389714
- ↑ 2.0 2.1 2.2 Sidik, Saima (29 January 2024). "'Wildly weird' RNA bits discovered infesting the microbes in our guts". Nature. doi:10.1038/d41586-024-00266-7. PMID 38291328. https://www.nature.com/articles/d41586-024-00266-7. Retrieved 31 January 2024.
- ↑ Pennisi, Elizabeth (26 January 2024). 'It's insane': New viruslike entities found in human gut microbes. doi:10.1126/science.znxt3dk. https://www.science.org/content/article/it-s-insane-new-viruslike-entities-found-human-gut-microbes. Retrieved 31 January 2024.
- ↑ Koumoundouros, Tessa (29 January 2024). "'Obelisks': Entirely New Class of Life Has Been Found in The Human Digestive System". ScienceAlert. Archived from the original on 29 January 2024. https://archive.ph/wip/WuR9D. Retrieved 29 January 2024.
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