[conqueso]

Searching HN for "mirror cells", I see at least 1 article warning of the dangers from more than 10 years ago. So, this has been a thing for a while. Any biologists here that can chime in on just how big of a risk they do pose? Is there a general consensus throughout the community that this research should end? Is this something that could be developed for bio-terrorism? Should work be started on developing mirror immune system cells, just in case?

[throwawaymaths]

no. antibodies will work just fine on a d-protein and one of their mechanisms of killing is to generate ozone, which is an achiral molecule.

there is currently ~no risk because generating mirror life is such a monumental task. we dont have a full biological bootstrap sequence currently. even syn1.0 which was a synthetic genome transplant and rebooting operation, required a living host cell to transplant the DNA into, and the genomic dna does go from a computer file, but only the smallest ~100 bp fragments are made by robots and chemistry; intermediate fragments are assembled and amplified in enzyme reactions, bacteria, and yeast.

in principle you could get these to be entirely in vitro, but the yields would be nearly nil. and the expense of mirror dna monomers is... i can't even imagine. you'd probably bankrupt a midsize nation on that. and theres no motivation to decrease the cost because there's not really any other practical use for mirror dna outside of fucking around scientifically. and thats just the DNA. our ability to synthetically make proteins taps out at around 150-200 residues (maybe 2-4x that if you can get clever with native chemical ligation) and the purification and isolation at that length is truly a nightmare, not to mention refolding longer sequences is also hard.

[ninininino]

I don't think anyone is worried about mirror proteins by themselves, they are worried about someone assembling a self-replicating/self-propagating mirror life, no? In which case, the fear is that you can't just run around ozone-ing every little colony of chiral-mirror version of cyanobacteria under every rock in remote Siberia or wherever.

[throwawaymaths]

1. > Should work be started on developing mirror immune system cells, just in case?

2. by way of direct response to your question. mirror nutrients (like scavenged AAs, even for autotrophs) are liable to be very scarce so they'll have one hell of a disadvantage makimg it on this world.

[roywiggins]

Not if you engineer your mirror bacterium to eat normal nutrients to get them started. Or they scavenge enough non-chiral molecules to eat that they get the opportunity to evolve the capability on their own.

[throwawaymaths]

building from non chiral molecules is prototrophy, not scavenging. anyways, existing lifeform already scavenge mirror molecules (especially d-ala since thats used in cell walls) so they are already competing in a quite saturated environment with highly adapted organisms.

[notfed]

I'm really curious to know the details here. What is the minimal set of dependencies for the simplest autotroph?

Clearly there was an original self-replicating cell and it was successful, so assuming we constructed the necessary proteins, why do you think it would be difficult the second time?

[jtwaleson]

This is the big question about abiogenesis. If it was easy then life in the universe could be very common. If it is exceedingly difficult, we might be alone.

What is the smallest set of molecules needed to self-replicate, and how common are the ingredients (& nutrients)? I believe all of this is completely unknown, but I havent looked into the research for years now.

[notfed]

I think for the purpose of this topic, we only care about the nutrition (to use your word) question. We can assume humans can intelligently bootstrap past the other abiogenesis problems.

And surely this shouldn't be a difficult question to answer, right? Put an autotroph (the simplest that we know of) in a test tube and give it a ever-stricter diet and observe how far you can go without it dying off.

[throwawaymaths]

syn 2.0? 3.0? is poking at the minimum set of genes for life, but that organism needs a lot of things to survive. i think it grows on horse serum

[M95D]

A completely "mirrored" organism is not that dangerous.

- It would still have antigenic properties, just not the ones we are familiar with, because antigens are proteins or proteins bound to sugars. Both have "left" vs "right" variants.

- It can't eat any ordinary food, except simple fats. Common proteins and sugars won't fit it's enzymes. That means it can't digest sugars, proteins or any combination that contains them. It also means it can't attack and decompose our tissues, so it would have no way to enter our bodies.

- With only simple lipids as food, it would need to take all Nitrogen from the atmosphere or inorganic compounds, which means it can't really be a pathogen for humans (or any animals) even if it could somehow enter our organisms. However, it could live on the soil and possibly be a plant pathogen.

- It's "mirrored" toxins won't have any effect on us. (But compounds that are normally benign possibly could be toxic if "mirrored" - I can't say for sure if it's possible.)

[foobiekr]

So much confidence about how this thing we’ve never encountered will not be a problem.

[slumpt_]

that’s fairly on brand for hackernews

doubly so if it’s from a person with no expertise in the relevant field

[M95D]

I studied microbiology and biochemistry and I work in a medical lab.

Let's agree that news and articles that are shocking, scary, but not likely to happen, aka. clickbait, are even more common than comments like mine.

[notfed]

Mirror organisms or not...we're doomed.

[Qem]

Mirror life would have no interoperability with normal life, in biochemical terms. Say, if a predator attacked a mirror bacteria, and ate it, it would be just like eating an inedible microplastic particle. A technological analogue would be to change tensions in electric outlets at random, between 115V and 230V standards, with no indication of which outlet has which tension. People would start blowing equipment left and right.

[ethbr1]

More specifically, it would have no interoperability with the portions of life that target chiral molecules.

Most critically, metabolic pathways.

But that isn't to say there isn't already varied chirality in nature [0]. The primary reason life is generally aligned to one chirality is because its very purpose is to interoperate with the living environment around it.

[0] https://en.m.wikipedia.org/wiki/Chirality#Biology

[phkahler]

>> Mirror life would have no interoperability with normal life, in biochemical terms.

That sounds like a good thing but... Our food chain starts at the bottom with bacteria turning nutrients into bio-molecules right? These bacteria are eaten by other things going up the food chain ultimately to us. What if some bacteria got loose at that bottom level and started eating all the nutrients with no natural predators? What if it out-competed those with predators? That might be game over for life as we know it.

I'm NOT saying this would happen, just that it one of thousands of possible scenarios one can come up with that go very badly. No one can say with certainty which things would or would not happen.

[roywiggins]

The report's scenario is a photosynthetic mirror bacterium eating the bottom out from under the oceanic food web. The existing predators would not be able to eat them, and so they would grow fast, and their predators would then shrink in population and that interaction would ripple upwards sending marine animals extinct.

[GenerocUsername]

It would be way worse than micro plastic and closer to your 115v example.

The parts would be similar enough to form bonds and trigger receptors, but different enough to become permanently stuck, unable to be processed.