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Unicellular "Enigma" Changes From Predator To Plant and Back

Posted by Soulskill on from the i-don't-eat-greens,-food-eats-greens dept.

SilverEar writes "Imagine a creature that swims and preys on others, but once it eats a certain kind of plant, that plant grows inside it, causing the predator to lose its ability to prey and start using sunlight to make its food. Its preying mouth is replaced by an eye that is needed to find sunlight. This is the Hatena ('enigma' in Japanese). The kicker: when Hatena reproduces, one offspring is a peaceful photosynthesizer with the sun-seeking eye, while the other is yet again a predator with a voracious mouth."

7 of 168 comments (clear)

  1. What happens when chloroplasts are removed? by az-saguaro · · Score: 5, Interesting

    Biology is full of promoter-inhibitor relationships, and this seems like an interesting one. When the algae is inside the protist, the host's "animal" behaviors and anatomy are suppressed, but they clearly remain in a latent state, ready to reactivate after fission. It makes one wonder to what extent chloroplasts remain as endosymbionts versus organelles in genuine plant species. So . . .
    . . .
    Does anyone know of any research where chloroplasts were removed from plant cells in culture, to see if the remaining cells revert to some atavistic animal-like exogenous-food-seeking state?

    1. Re:What happens when chloroplasts are removed? by Anonymous Coward · · Score: 1, Interesting

      Does anyone know of any research where chloroplasts were removed from plant cells in culture, to see if the remaining cells revert to some atavistic animal-like exogenous-food-seeking state?

      There's always the venus fly trap. But, I'm pretty sure if chloroplasts were removed, even in culture, the cells would die. Multicellular plants can't roam around to find food, why would they still have that trait? (the supply of birds would quickly be exhausted)

      It'd be more interesting to insert chloroplasts into animal cells, to see if they turn into plants. (plants are more likely the ancestor of predators)

    2. Re:What happens when chloroplasts are removed? by az-saguaro · · Score: 4, Interesting

      Yes, you are exactly correct, that sticking chloroplasts into animal cells would be the necessary flip side of that experiment.
      -
      I was not referring to turning pine trees into Night of the Living Dead. What would be interesting is to see what would happen to algae under these circumstances, or to cultures of moss cells or flowering plant cells. Pick a popular research plant - tobacco for instance - and then pull the chloroplasts out of a few cells, then stick them into a cell culture medium - e.g. agar petri dishes or mammalian cell culture flasks - and see if they become planktonic, aggressive, nutrient-tropic, or if they start to express cell surface structures or other organelles related to sensing and locomotion. Since the algae are phylogenetically much closer to all of this, it seems plausible that they might revert to animal-like forms and function.
      -
      If nobody has ever done these experiments, now would be a good time.

  2. Re:PETA will be confused by OeLeWaPpErKe · · Score: 3, Interesting

    Actually once this cell totally integrates this endosymbiotic lifeform (the next step) it might very well become eukaryotic. Ironically that would make it an eukaryotic plant, which would presumably very easily evolve back into a predator.

    when Hatena reproduces, one offspring is a peaceful photosynthesizer with the sun-seeking eye, while the other is yet again a predator with a voracious mouth."

    The explanation is simple : cell division in the parent organism does not trigger cell division in the endosymbiotic lifeform. That endosymbiotic lifeform might very well be thought of as an infection.

  3. Advantageous Evolutionary trait by DadLeopard · · Score: 2, Interesting

    This gives the organism the ability to take advantage of any advances in Photosynthesis that the prey has made! Thereby incorporating them in future generations! Like some people I know! Always upgrading to the latest and greatest!

  4. Re:PETA will be confused by rpillala · · Score: 5, Interesting

    No, not the same rights as humans, just the same rights as pets. Even this is an oversimplification but I think it gets the point across.

    The point being that it is not appropriate to speak of animals having all the same rights as humans. I think this is well understood. The right to vote, for example, does not make sense since it presupposes knowledge of language, politics, issues etc. The rights that PETA members ascribe to animals, most basically, are the rights not to suffer and die at the hands of humans. These aren't that far out, when you consider the "arguments" in favor of the suffering and dying.

    --
    When the axe came to the forest, the trees said, "Look out - the handle was once one of us."
  5. Re:PETA will be confused by OeLeWaPpErKe · · Score: 2, Interesting

    You're obviously right, plants are eukaryotic. Sorry.

    Why would it have genes for producing an eye if it was regarded as an infection?

    How exactly would you call a lifeform that changes the operation of a target cell for it's own benefit ?

    Evolution theory is more and more saying that genes spread by viruses, and we have little trouble calling those infections, no matter how useful they are in any particular case. So why feel inhibited calling this an infection ?

    Here's what happens. You have a virus ... any virus. It contains a series of advanced genes. Probably copied from it's previous victims, or whatever. This virus becomes successfull. So successfull in fact, that there isn't a single human that isn't infected after a while.

    So what happens next ? The evolution of the virus and the evolution of the human species are now locked together. The only way the virus can improve it's fate is by making humans more successfull, and the only way humans can become more successfull is by making the virus more successfull. So the disease generating genes are deactivated one by one, for they stand in the way of the success of the "new" human lifeform, and the interesting genes are used more and more.

    AIDS could become an example of this, if we're not careful. It contains several very advanced genes. I haven't the faintest clue what this might be useful for, but AIDS contains code "runnable" by human cells to convert RNA into DNA, something our cells can't do, and it contains code that allows for the creation of a special kind of membranes. One thing AIDS is doing is making this code available to a large part of human evolution.

    There are lots of historical occurances of this. Some virus infects the entire human population, and it's DNA code is reproduced verbatim in each of us, despite the virus itself no longer appearing in nature. At least 50% of our DNA code is the result of our ancestors getting sick with virii. 3 "full" such viruses have been found in the human genome. One can only imagine how many partial viruses are in there, whose code is slowly evolving out of the human genome.

    The difference between prokaryotic and eukaryotic cells comes down to 2 internal membranes. It may look very different under a microscope, it isn't all that different. One way to make this happen through evolution is by having an endosymbiotic relationship with another bacterium, which has a membrane. Then, gradually, since the 2 species evolution is locked together, the endosymbiotic lifeform degenerates into a single function device. This has been the accepted explanation for a few years now, ever since eukaryotic cells have been found with dual-membrane mitochondria, within that first membrane a kind of polar body was found, indicating that the mitochondria was once part of a proper cell that lived separately from it's host. Since then bacteria that look a lot like mitochondria have been found, further confirming the hypothesis. We have exactly the same mitochondria, but with only a single membrane.

    So it seems that cells "evolve" from prokaryots to eukaryots by "eating" the difference. The only step to prove this that's really left to do is demonstrate this specific evolution in a lab.