Worldbuilding: Buddy, Want to Buy a Polymerase?

There’s no fight like a family fight. Or as homicide detectives have been known to say, “Nearest and dearest has the motive with the mostest.” Oddly, this often holds in biology and ecology as well. The more closely related something is to you, the more likely it is to be competing for the resources you need to survive. Walnuts and other trees produce chemicals to prevent seedlings from growing near their roots. Birds sing and physically attack other birds of the same species to protect enough territory to survive in. Mockingbirds are opportunistically omnivorous, so they imitate every other bird they hear to chase them out. And so on.

Competition between individuals of the same species, even close relatives, starts very early; in placental mammals, pretty much from the moment of implantation. It’s hard to wax poetic about the miracle of motherhood when you know there’s actually an intense biological struggle going on between the baby and the mother for who gets what resources, how, when, and how fast. I’ll spare you the grisly details. Suffice it to say prenatal vitamins are an extremely good idea. Especially enough calcium. Eep.

Which makes you wonder how much calcium investment is saved by not having hard shells, and how the whole messy business of placental reproduction got started in the first place. The short answer to that appears to be viruses, as I’ve mentioned in other posts. But that leads to a deeper question: how did our genome integrate viruses that form masses of mostly-undifferentiated tissue without blowing up? Viruses come in DNA or RNA, and transcribe their code into RNA which then gets translated into the proteins that cause cellular havoc, but these seem to be RNA-based viruses and that doesn’t get turned back into DNA….

Or so we thought, until HIV gave us one of the first stunning counterexamples with reverse transcriptase. Ouch.

Since then we’ve discovered a host of other nasty viral tricks, but now it looks like the cellular cloak and dagger doesn’t all go one way. Mammal cells have 14 DNA polymerases, usually meant to repair DNA, copy it, or transcribe it into RNA. Researchers from Thomas Jefferson University have found that polymerase theta is absolutely lousy at normal DNA repair, but awesome at turning an RNA template into shiny new DNA, even able to change its own protein shape to fit the bulk of an RNA molecule; something the other polymerases just can’t do.

The stumper, of course, is why do we have a polymerase that will do that in the first place? It seems like a wide-open door in the middle of our high-security immune system, viruses walk right in. Worse, polymerase theta tends to be produced in large quantities in cancers, leading to their growth and drug resistance. So it’s not just a potential viral back door, it opens the gates to your own cells killing you horribly.

So. Why?

At this point in time nobody’s sure. Maybe it’s meant as a last-ditch repair mechanism for shattered DNA from remaining whole RNA in the cell. Nobody knows, they’re working on how to find out.

So here’s the seed for an SF plot: what might this really be good for? And what goes wrong – or right – when it clashes with genetic engineering?

Me, I’m wondering if it’s an elaborate species-wide genetic counterespionage, high-risk but potentially high-reward. If a virus comes up with something useful, maybe we steal it….


21 thoughts on “Worldbuilding: Buddy, Want to Buy a Polymerase?

  1. I want to disagree about the characterization of the natural world as being dominated by competition (shades of exploding lobster brains, there), but I’m too distracted by the sci-fi. Somebody who is (accidentally or deliberately) genetically engineered to acquire traits of viruses or of other organisms, that reminds me of the c’naatat from Karen Traviss’s Wess’har series. It’s an alien parasite with one goal: to keep its host alive. Throw a c’naatat infectee under the sea, and they’ll quickly develop gills and, if needed, echolocation, electroperception, and/or night vision. They might also randomly turn blue or grow a tail or something. Over time, their bodies inevitably change as they live their lives; c’naatat always tries to optimize. It comes with a bonus of immortality, bringing in all that sweet, juicy Who Wants to Live Forever angst, along with the profound alienation from the infectee’s society and their own body as this alien entity keeps changing them without their will or their control. I think there are a lot of directions you could go with the premise that are completely different from Traviss’s.

    Liked by 1 person

      1. Ah, balancing conflicting demands!

        That works much better– I, too, was trying to put a finger on what exactly didn’t sound right in the description, especially since (of course) if the mother dies, so does the offspring, unless they can cut it VERY close. (And without help, that happens more than I like to think about. 😀 )

        Liked by 1 person

      2. *laughs* Sounds like any born baby– if there was a regulation of demand beyond “what I can process,” that would be just another thing to go wrong. Even with it only being limited by “what I can process,” you’ll still get malfunctions– in normal speak, a baby that will stop eating before he’s full. (there are tricks to deal with this, but there’s a lot of variations)

        So it only makes sense for the regulation to be on the supply side.

        Liked by 1 person

      3. Mine were a HOOT. A few outliers.

        First baby: hot tamale candy. Not cinnamon. Just hot tamale candy.

        Third baby: Mochas from the little shop in front of our grocery store.
        Not milk (whole), chocolate, or coffee– possibly they were using full creamer or something, but wow.

        Polish sausage.
        Not beef, or meat, or sausage, but specifically polish sausage…..

        Liked by 1 person

      4. Replying to the wrong comment because it won’t let me farther down (sorry):

        Crab. I didn’t have a whole lot in the way of pregnancy cravings, but there was this one time I’d been feeling “bleh” for a few days and apparently what fixed it was a pile of crab legs.


  2. When the aliens were inventing the human race, they programmed a back door into the genetic code in case they ever need to exterminate us.

    Humanity enters the galactic community and discovers that we have weaker immune systems and nobody else gets cancer.


      1. We’re designed to “adapt and overcome” no matter the odds. Yet another reason why we are so darn hard for aliens, gods, and demons to kill off. They think we’re like them when we’re not. We’re tougher. 🙃

        Liked by 3 people

      2. As somebody put it, humans are capable of doing surgery on themselves in extremis, and surviving; we heal from wounds that would kill a lot of other species.

        Heck, I read an account of a woman who successfully did her own C-section. Mother and child both lived. Whooooof.

        Liked by 2 people

      3. And, I don’t buy it as a conspiracy.

        ‘elaborate’ and ‘extraordinarily long term’ are not necessarily deal breakers for a conspiracy.

        But, being able to pull it off seems to require abilities that would make it unnecessary.

        Thing about engineered sabotage, implementing it costs energy, and doesn’t provide competitive advantage. So, if you have all extant humanoids in custody, you can be sure that all cohorts at the time have the mod, but you could just kill them all instead. If you don’t have them all in custody, you can not be sure that your modified subset will be successful at ensuring the trait passes to subsequent generations.

        If a mod is not functional in some way, there is a chance that random mutation might tend to disable it over time.

        Basically, it is the sort of conspiracy theory where you would really need to establish that it is in the character of the saboteurs to operate so irrationally.

        Deep pre-history conspiracy theory has born some very interesting fruits over the years, but the blinder the handwaving adn more present oriented the paranoia, the less it holds up over the course of the story.

        Liked by 3 people

      4. The assumption for it as a conspiracy is that the aliens are responsible for humanity in the first place, which is an assumption made in some Scifi.
        Often to explain why all the alien chicks are “compatible.”

        It’s not a matter of grabbing all the humans and putting in a backdoor, it’s a matter of grabbing some primates, creating humans, dropping them down to take over, and including a kill-switch.


      5. Also, If you put enough ‘good stuff’ into the humans for them to displace the primates, what is the pay off for you with the kill switch millions of years later? Why not just directly kill the primates?

        This maybe isn’t as extremely bad as an assassination plan that involves waiting for macroscopic quantum tunneling to kill someone by pure random chance.

        Liked by 2 people

  3. Maybe it’s some sort of mimic defence mechanism? Copy the virus, and the virus becomes less effective against us?

    Would be interesting if humanity adapts to local area/planet through adopting dna from local viruses. I mean I always imagined that humanity would wander in different directions in closed systems like space stations, moon colonies, settled planets.

    Liked by 2 people

  4. Well, that gives me a route for the Deliberately Mutated Humans to do stuff….


    Well, since the usually function for polymerase is to make RNA, and this one turns it back into DNA, maybe that’s its purpose?

    Liked by 1 person

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