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Largely we don't know. That's what makes them cool. This opens up a fairly large debate about where you draw the boundary of "life", "organisms", and "entities
by ababaian 2y ago
Largely we don't know. That's what makes them cool. This opens up a fairly large debate about where you draw the boundary of "life", "organisms", and "entities". It's a fun debate to have over a few beers since there is no objective correct answer.
My view is that Obelisks are more like Viruses or Viroids, or some kind of mobile genetic element. The key detail is that they appear to be strictly RNA elements (they don't have a DNA counterpart). So they're most likely using host RNA transcription machinery to make more copies of themselves, this is what viroids and satellite viruses like "Hepatitis Delta Virus" do.
What do they do? Well that's the right question. My guess is the kinds of things that bacteriophages do, Obelisks do too. Exploit cells to make more copies of themselves as selfish replicators.
- bicx 2y agoIs it possible that these may cause diseases that previously went unexplained?
- ababaian 2y agoIt's possible, yes. But right now there is no evidence for Obelisks being linked to any disease, not even a phenotype in the cells carrying them. Keep in mind also that these elements likely interact with bacterial cells, so effects on human disease would most likely be indirect.
- lukeschlather 2y agoIs there really any evidence that they are parasites and not part of the host's machinery?
- ababaian 2y agoThese are two distinct questions. Are Obelisks part of the self? If you think of the "host" as being made up by it's DNA, then these are not part of that set, since they are not found in DNA copies. Or is an organism it's RNA? If it's the RNA that's the organism, then sure you could say this is part of that organism in that it exist as organelles of sorts, like mitochondria or chloroplasts (but in RNA form). The second question is if it's parasitic, mutualistic, or neutral. If it's a parasite it should cause a fitness defect to the DNA organism's replication. As of yet I haven't seen evidence of this at the cellular level. But there is a strong argument that by depleting cells of nucleic acids (RNA) would have to be at least minimally parasitic. That is of course unless they confer some advantage to the cells with Obelisks. In which case, why don't all microbial cells have Obelisks. Importantly, the relationships between all the various Obelisks at least for now, is not lining up with microbial genome evolution. This would mean they are jumping from genome to genome. Now you're in a late night pub discussion about where we should be drawing the boundaries of life.
- brokensegue 2y agoI'm unclear why we are calling these a new class of life rather than just a new kind of virus. Their shape?
- ababaian 2y agoI think this is the journalist playing at the idea that we don't have a universally accepted definitions of "life", "virus", "viroids", "mobile genetic elements", "plasmids", or the other words that describe what I view as the agents of evolutionary games. It is kind of catchy way to raise that conversation though eh!
- throwup238 2y agoViruses have capsids which are protein shells that envelop them. These are just bare RNA strands, which are considered viroids.