Ban Mirror Cells

Imagine a mirror reversed cell, made of mirror-reversed molecules. If it gained energy via photosynthesis, or via special adaptations that enable it to eat ordinary life, the fact that it was immune to ordinary predators and disease would give it a huge advantage; it could take over much of the biosphere. Sounds like a good reason not to make mirror cells right? Unfortunately, there are now big efforts to develop mirror cells, because they’d be a handy biotech tool for pumping out lucrative mirror proteins. Yes this is a real gain, and yes there are ways to try to stop mirror cells from getting loose and destroying the biosphere. But really, the gains here seem easily outweighed by the risks. This is a pretty clear case justifying strong global regulation or bans. Alas, I can find no movement in this direction. Details:

A life-form … based on mirror-image versions of earthly proteins and DNA. … If it worked, those new cells … might also open up new avenues of discovery in materials science, fuel synthesis, and pharmaceutical research. On the down side, though, mirror life wouldn’t have any predators or diseases to limit its reproduction. …

A catastrophe was under way across the Charles River at Genzyme, one of the largest biotech companies in the world. … A virus that disrupts cell reproduction infected one of the bioreactors. The entire plant had to be shut down. … When Church talks about mirror life’s quirky advantages, invulnerability to this kind of mishap is high on his list. “Viruses can’t touch a mirror cell,” … This makes mirror life a potential workhorse for biotech. … Church has been hacking the ribosome. … His plan is to make one that reads regular RNA transcripts of genes but can string together wrong-handed amino acids to form mirror proteins. … Church and his team have cracked the first step. … Last year his team got a synthetic ribosome to self-assemble and produce luciferase, the protein that makes fireflies glow. And he has a library of mutant ribosomes that have the right kind of sockets—they’ll accept mirror amino acids. This is where the money comes in. Some of the most valuable drugs are actually tiny proteins that include wrong-handed amino acids—like the immunosuppressant cyclosporine. To manufacture it, pharmaceutical companies have to rely on an inefficient and expensive fungus. A hacked ribosome modified to handle both normal and mirror amino acids could crank out the stuff on an industrial scale. …

Church thinks even bigger. A manufacturing ribosome would be great, but a fully domesticated mirror cell—able to synthesize more-complicated stuff—would change everything. … vats of virus-proof mirror cells could pump out biofuel, lay down nano-size organic circuitry, and even extrude organic cement foundations for skyscrapers. …

Of course, mirror life could also kill us all. … Just as viruses from our side of the mirror can’t infect it, mirror pathogens can’t infect us. … They might be poisonous, though. … To a mirror cell, … there’s just not enough nutrition for them in the wild. … On the other hand, if mirror cells somehow evolved—or were engineered—to consume normal fats, sugars, and proteins, we might have a problem. … Mirror cells would slowly convert edible matter into more of themselves. … If mirror cells acquired the ability to photosynthesize, we’d be screwed. … All it would take would be a droplet of mirror cyanobacteria squirted into the ocean. Cyanobacteria are at the base of the ocean’s food pyramid, converting sunlight and carbon dioxide into more of themselves … That would wipe out the global ocean ecology. …

“I would be the first to say that we shouldn’t make a photosynthetic mirror cell,” Church says. “But I’m reluctant to have a moratorium on something that doesn’t exist yet.” He says he’d build safeguards into his mirror cells so they’d perish without constant care. And the advances in synthetic biology required to transform those first delicate mirror cells into anything that could survive in the wild are even more remote.

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  • Zach

    If mirror cells can have special adaptations to eat ordinary life, how long before ordinary life has special adaptations to eat mirror life?

    • DK

      Almost instantaneously. It’s not like D-amino acid cata- and metabolism are something unknown and not present in practically every cell (e.g., our brains contain significant concentrations of D-serine and N-methyl-D-aspartate). Lots of bacteria and fungi will happily metabolize D-amino acids. Give them D-aa as the limiting carbon source and selection will take care of the rest in no time.

    • Dan Weber

      Even if higher organisms couldn’t get nutrition from them, wouldn’t those higher organisms still eat them, “thinking” that they could?

      A gazelle made of mirror cells wouldn’t be immune to a lion.

    • wladimir

      Would it be possible in the first place for an organism to be able to absorb both ‘ordinary life’ and ‘mirror life’? Sounds unlikely to me, the molecules are ‘tuned’ either way. We’d be as poisonous to them as they are to them.

      And as ordinary life is so much more common than mirror-life, there is no chance it would survive in the wild with all that poison. This is probably the reason why there is only one chirality of life on earth, left-handed won the ‘coin toss’ and broke symmetry.

  • The scary thing is that it’ll probably be possible for a DIY biohacker to make a photosynthetic mirror cell in his garage someday, ban or no ban.

    • Buck Farmer

      This article persuades me a ban is precisely what we don’t need.

      Assuming a ban wouldn’t be perfectly enforceable – and the risk of a crack in the ban is catastrophic – we need to operate assuming that eventually they will be produced and will break out – i.e. we need mirror-phages and other weapons.

  • Unknown

    As Zach implies, the idea of mirror life consuming the biosphere is extremely improbable. Long before that happened the biosphere would evolve its own defenses, if not the ability to eat the mirror cells, then at least the ability to defend itself from being eaten, or just to kill the mirror life.

  • Robert Koslover

    And… maybe that’s the great filter you’ve been looking for. 🙂

    • Oscar Cunningham

      Is there evidence that life will always evolve in a chiral manner?

      • Tim Tyler

        Complex machinery tends to be chiral. That’s because there are so many more ways to be chiral than symmetrical.

    • Dan Weber

      If a L-lifeform would be at such an incredible advantage in a R-dominated world, and vice versa, then either

      1. the development of new lifeforms is extremely rare; rare enough to be the great filter. Or

      2. the ecosystem would contain a significant amount of both L- and R-type lifeforms.

      #2 is not true by observation.

      I’m not a microbiologist, though.

      • You would have to develop more than a new mirror lifeform – it would have to have working photosynthesis from the start, which is very unlikely. There is no primordial soup of nutrients waiting to be picked up now, not like there was when life first started on earth.

  • Nayan

    Exactly. If it is possible to engineer mirror cells to consume normal fats, then it should also be possible to engineer normal cells to consume mirror fats.

  • We’re far better than you think at making life that cannot live outside laboratory. This is a long solved problem. All you need is a single nutrient they cannot synthesize themselves – and we don’t even need to worry about acquiring it via gene swap (such cells randomly creating necessary enzymes de novo is a pure fantasy).

  • Non-mirror bacteria are almost equipped destroy mirror counterparts already. Natural amino acids and sugars are reversed in relation to each other, in fact our cells use that as a marker to sort which machinery to send them when digested; it’s cheaper than checking the active parts. At least it was in the ancestral environment. You pointed out that it could change. On the bright side choking up amino acid machinery with mirror sugars (and sugar machinery with mirror amino acids) may simply kill both organisms.

    Which is not much of a bright side, given that we can’t yet fix either digestion problem in humans.

  • Predators would often consume the new microbes before noticing that they weren’t nutritious. Some parasites would have effective attacks, and at some level, there is valuable energy to be freed, even if it’s wrong-handed. I don’t think these new strains will be invulnerable.

  • If I’m assuming correctly, mirror cells would consist of molecules of the opposite chirality to those that tend to be used in terrestrial life: L-ribose and L-deoxyribose in its nucleic acids in place of D-ribose and D-deoxyribose, D-amino acids in place of L-amino acids, et cetera.

    It would first seem to me to be a ridiculous feat to make such a cell. We have not been able to make non-mirror cells from scratch and it just so happens that one of the best ways to make pure chiral compounds is to use biological mechanisms. This would be difficult as most biological synthesis pathways are geared toward making molecules of opposite chirality to those needed for a mirror cell.

    I’d think that you’d want an autotrophic mirror cell, because then you don’t have to go through the pain of trying to make it process material of the opposite chirality to its own (or at least not as much), so I’d go for a cyanobacterium template, but I’m thinking that this is decades into the future.

  • It seems that in order for a mirror cell to be able to eat and derive energy from normal cells they would need to be able to make non-mirrored molecules, requiring ribosomes that can make non-mirrored molecules. It seems very likely that such ribosomes would be just as susceptible to regular non-mirror viruses as any other ribosome.

  • vaniver

    Uh… what?

    Reversing the chirality of molecules does not turn them into a terrifying monstrosity. The fundamental chemistry is still the same- it will still have to eat (limiting growth), it will still be weak to the same chemical attacks, it will still be destroyed by extreme temperatures, and so on. Indeed, the fact that they say mirror *viruses* cannot infect us seems telling to me (and I suspect it was the journalist who generalized that to ‘pathogen’).

    I mean, this post seems written in total ignorance of the gray goo threat that’s already all over you! I mean, are we supposed to be scared when they say “this living thing might make more of itself out of food!”?

    • Reversing the chirality of molecules does not turn them into a terrifying monstrosity. The fundamental chemistry is still the same- it will still have to eat (limiting growth), it will still be weak to the same chemical attacks, it will still be destroyed by extreme temperatures, and so on. Indeed, the fact that they say mirror *viruses* cannot infect us seems telling to me (and I suspect it was the journalist who generalized that to ‘pathogen’).

      Indeed, this was my thought. If one of the branches of a molecule is flipped, how does that stop me from metabolizing it? Are my enzymes (or whatever) *that* specialized that they just can’t handle it, and would have to regurgitate it to its environment intact? Would such mirror organisms give off scents that regular olfactory systems don’t recognize?

      But I’m no biologist, so I don’t know the answer.

      • ad

        Are my enzymes (or whatever) *that* specialized that they just can’t handle it

        I would not be surprised if they were: my left shoe is so specialised that it just can’t handle my right foot.

      • Allan Crossman

        “Are my enzymes (or whatever) *that* specialized that they just can’t handle it”

        As a biology student let me tell you: almost certainly yes. The substrates (L-sugars, D-amino acids, etc) just won’t fit right.

      • JasonSL

        Humans cannot digest L-glucose, but it tastes just as sweet to us as D-glucose (the normal kind).

        Yeast can survive with D-alanine as their sole nitrogen source. Non-mirror amino acids are L.

        As a previous commenter noted, however, what matters is not whether non-mirror predators can digest mirror cells, but rather whether they will (try to) eat them. Human phagocytes will eat almost anything not marked as “self”, including iron filings, and kill what they eat by non-chiral chemical means (reactive oxygen species) which would be equally effective against mirror bacteria as they are against normal bacteria.

        If we desired, we could design and evolve mirror phages to infect mirror bacteria. These phages would be harmless to non-mirror life since their genetic material would be unreadable by host ribosomes.

    • What are you going to do, heat up the whole ocean to kill off mirror phytoplankton? Gray goo is more dangerous when you haven’t coevolved with it for 4 billion years.

  • Scientists should first work on something that can kill mirror-cells, so we are robust against the DIY biohacker hypothetical. But don’t let anyone else know about it, so people don’t try to come up with defenses against it.

  • Abelard Lindsey

    I don’t think mirrored cells could be designed that consume existing “normal” fats and proteins. If mirrored cells could consume existing fats and proteins, they would also be susceptible to the same viri as well. Mirrored life would not have any competitive advantage over conventional life. I think the fears surrounding mirrored life are groundless.

    • Buck Farmer

      First, at least some fats don’t have chirality (i.e. mirror and normal fats are identical). The article linked alludes to this.

      Second, mirror cells don’t need to eat regular cells to kill them. They could physically crowd them out, cut off access to sunlight, compete to consume non-chiral resources like water.

      On the plus side, they can probably be killed by radiation, dessication, and many other non-biological weapons.

  • I think a ban would be bad, due to hampering useful research. The hypothetical mirror-cell apocalypse seems like bad science fiction to me.

    Most mirror life will find relatively little to eat – and so it is unlikely to be a source of concern.

    • They wouldn’t need to eat to be dangerous. If mirror autotrophs crowded out regular autotrophs, we would be screwed.

      • As I understand it, “autotrophy” doesn’t mean “not dependent on chiral organic molecules”. It just means not dependent on organic compounds as an energy source or as a carbon source. There are still vitamins and the like. For instance vitamin C is chiral and is needed for plant growth. Once you account for that issue, the for remaining autotrophs are mostly bacteria – and do not seem very threatening.

      • Buck Farmer

        Tim, mirror-cyanobacteria are a threat if they can’t be consumed by phytoplankton and the like. The idea discussed in the article is that they crowd out normal-cyanobacteria and thus starve the rest of the food chain that depends on normal-cyanobacteria…

        …thus reseting us evolutionarily to the emergence of cyanobacteria with none of the machinery to support the complex edifice built on top of it.

        The author projects a 300-600 year timeline which would certainly be too fast for complex lugs like us to become chirality-agnostic, but seems like a reasonable time for the cyanobacteria-phages to develop a taste for mirror-blood (perhaps with a little human intervention).

      • Tim Tyler

        Cyanobacteria are a phylum – with thousands of species. I don’t know what their nutritional needs typically are – so the plan may be highly impractical – but if we pretend that cyanobacteria can make everythying they need from sunlight and raw materials, this turns into a classical “grey goo” scenario – where some microscopic indigestible entity munches through the biosphere. Most such scenarios are unrealistic. Trying to produce something which competes successfully with 4 billion years of microbial evolution is not that easy. Making microrganisms that are indigestible for very long is also tricky. If you can get a synthetic organism to survive in the wild at all, I figure the most likely result is a slight rearrangement of the ocean’s flora – not the wiping out of the global ocean ecology of the article.

      • Tim, nutrient requirements for autotrophic algae are pretty slim. This is apparently enough:

        No chiral organic molecules there.

      • Thanks. I don’t think any of those molecules is chiral – unless you count the “heptahydrate” business – and any asymmetries there are probably not biologically significant.

  • Russell Wallace

    As has been pointed out, not only is it trivial to make a cell such that it can’t survive in the wild, it would require extraordinary effort to make one that _can_. Complex capabilities do not arise in one shot by accident. Furthermore, the technology that could make a mirror cell, could easily make mirror viruses that would kill such cells while being harmless to regular life.

    More importantly, your assessment of risks is, to put it mildly, highly incomplete. You’re calling for a ban based on a hypothetical risk that won’t actually happen, for reasons that have been explained. You’re _assuming_ we don’t need mirror cells very badly, but you don’t actually have any basis for that assumption; you don’t know what key breakthroughs they might make economically feasible. Worse still, every precedent of enacting bans based on imaginary scare stories, increases the existential risk that bans so casually passed, will end up covering things we end up not being able to do without.

    If you want to be of service to humanity — or even to refrain from being actively harmful — try calling for the repeal of existing bans, not the passing of new ones.

  • IVV

    So… why hasn’t the other handedness evolved on Earth? Why aren’t we sharing space with mirror organisms now?

    • That’s not how evolution works. You would have to essentially replace the entire genome in one step with a different, mirror genome, which is astronomically unlikely. Evolution mostly optimizes what it already has to work with.

      • IVV

        But the step taking us from nothing to the building blocks of life would have to be taken for both chiralities, before DNA. This is the evolutionary step I’m referring to, pre-life. Nothing needs to change chiralities, it’s all in the “decide a chirality” step.

        The initial chirality can be found down to simpler molecules than DNA. Since both chiralities are present in a general chemical process, one would assume that the conditions that started life down the path for left-handed proteins also are conducive to creating right-handed proteins in a pre-genomic environment.

        So, it would appear that there is a filter here. I can think of a few possibilities:

        Perhaps left-handed molecules have some inherent advantage over right-handed ones. Given what comes out of the chemical processes in drug manufacture, I doubt this.

        Perhaps there’s a first-mover advantage, and the left-handed molecules were lucky enough to form RNA first. They then crowded out the right-handed molecules. This may suggest that reintroducing mirror cells could pose a risk, but then again, when it comes to crowding out, we have the advantage in numbers.

        Perhaps we just simply have absolutely no idea how life first formed, and it requires some extra cosmic catalyst that came (comes?) with a chirality.

        However, mirror life never developed with our life, and there must be a reason.

      • Chirality is down to chance or the weak force – but probably chance.

      • IVV

        If it’s chance and chance alone, then that would mean that there must be a first mover advantage–perhaps creation of the chiral catalyst.

      • Jess Riedel

        If abiogenesis is extremely unlikely (i.e. it’s where most of the great filter lies) then it’s not first-mover advantage or a fitness advantage (through a CP-violating weak-force effect). It’s just that life is very unlikely to develop at all, so when it does develop on a planet it does so just once, and the chirality is random.

  • Dan Weber

    This is like what I was getting at above. Whatever made the primordial soup develop the first chiral lifeform, it seems to have been really rare. (How long would it have taken the first chiral molecule to “colonize” the entire soup and crowd out newcomers? Billions of years? Millions? Thousands?)

    Is the chilarity the same for isolated lifeforms, like those bacteria living in superheated pools of water?

    As a thought experiment, I think it’s really cool to imagine that, if mirror cells had evolved, what life on earth would be like now. We would essentially have two separate lines of evolution. They would have similar environmental pressures, including each other.

    Science fiction novel idea: a MacGuffin changes the chirality of half the life forms on earth. Half the human population becomes alien to the other half, not able to interbreed or even eat the same food.

    • IVV

      That soup must have not only been rare, but small. Small enough that one chirality could dominate in short enough a time that the other chirality wouldn’t exist as well. I’m guessing it would require either extreme luck in a tiny tiny pool (large enough for only one archaea to form and leave) or a chiral catalyst.

      But then how is the catalyst made?

    • JasonSL

      We could eat some of the same food. Fatty acids are achiral, as is glycerol. We could get energy out of the same wine or liquor, as ethanol is achiral. Sugars and proteins, of course, are a different story, as are vitamins.

  • Which Dokta

    Mirror viruses evolve to infect mirror cells.

  • LJR

    Ummm. Guys.

    You are smoking hashish and loving the sights.

    Read some Franklin Harold – that will splash a little cold water on your overheated fantasies. In short, “it takes a cell to make a cell.” The ONLY way we can even approach our childish fantasy of “creating life” is by hacking together some monstrous DNA and sticking it in a living cell. Obviously this will not work with reversed DNA. We are no further along in “creating life” as an autopoeitic entity from scratch than we were fifty years ago.

  • jb

    It occurred to me last night that this may already have happened (dumping photosynthetic mirror-bacteria in the ocean). Maybe that’s the great filter!

  • Pingback: Mirror Cells: Something New to Be Afraid Of | John Goodman's Health Policy Blog |

  • This is just silly. If there is one thing we’ve learned in recent years it’s that everywhere there is energy and water on earth there is life feeding on that energy. Utilizing the energy stored in a mirror photosynthetic life form would be far less difficult than harassing the energy from deep sea ocean vents.

    I mean fuck worst comes to worst you can harness energy super inefficently by gather the microbes up and burning them. Indeed, I suspect there are already bacteria that can metabolize these mirror cells (perhaps inefficently) and would quickly enter into symbiotic relationships with many ocean lifeforms.

    It might be a catastrophe for whales and other large ocean going vegetarians but hardly the end of the world. Hell, as some scientists keep pointing out WE DON’T KNOW THEY DON’T ALREADY EXIST!! Our current detection mechanisms aren’t really set up to look for mirror organisms.

    Moreover, the idea that they would even manage to hold their own against non-mirror organisms is sketchy. Through mechanisms like bacterial gene swapping and incorporation of genes from viruses the non-mirror organisms benefit from a vast evolutionary economy of scale. Indeed, it might well be a simple economy of scale issue rather than any rarity in the production of new life that explains the dominance of the current chirality. Immunity to a few viruses isn’t that big a deal compared with the jump start you can get sharing beneficial mutations (even extremely indirectly and rarely).

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