Classify, you Yellow-y Slimy Mouldy maze solver!

Physarum_maze
Pysarum solving a maze[5]
Physarum polycephalum, I know you’re not one of those anti-membrane-bound-organelle things, in fact you eat bacteria. So heartfelt props on being a contributing member of the anti-prokaryotic league.

But lets not get too friendly. I have my issues with you. Lets start with yellow… it’s not your colour. Actually there is no colour that will match your unparalleled protist madness. (What is a protist anyway? We can’t figure out what a protist is other than eukaryotic.) Why are you galvanotactic[1]? How do you anticipate periodic events[8]? What does acceleration-stimulus even mean to you[2]? Do you really have to do some weirdly efficient shuttle-streaming motion shit[3]? Last I checked, your “many-headed slime” pseudonym didn’t make you suddenly grow even a single brain.

Though you look like a gross yellow pulsating blob, somehow move in the superbly mesmerizing ways of shuttle streaming. We have real limbs and nervous systems and muscles that work by the usual sliding filament method that aid in our motility while you go around doing some strange endoplasmic streaming that reverses direction periodically on the time scale of minutes by contractions of the actinomyosin system in a Ca++ dependent fashion[4] to generate contractile forces of up to 180g/cm2[3]. That’s like more than normal human blood pressure, which if you didn’t know, takes a lot to regulate. (Still only half giraffe blood pressure but they have already been dealt with in FU, Penguin). We tried to model your streaming with 12 parameters representing Ca++ and cAMP levels (and whatever else we could think of). We have some ideas about how you oscillate ATP and tension in phase and Ca+ and cAMP out of phase[9]. But in my opinion, you should stop working on your moves and start working on classing up you looks instead by being less yellow-y and less slimy and less mouldy, but I’m sure you think you’re beautiful on the inside or something. Well, we thought so too, till we started looking inside you and what we found was frankly disturbing. Apparently, this shuttle streaming lets you optimize networks of tubes to locations of food sources?

When we challenged you with different configurations of food sources, we found that you can come up with very efficient networks of tubes to connect them. We understand you want to keep your average degree of separation (AS) between two food sources to a minimum which can be achieved with some not-so-complicated logic that even we can wrap our brains around. But then you go and maximize your Fault tolerance (FT) to total tubular length (TL) ratio as well so that you can have the robust to injury while minimizing your tube length[6]. How can you solve the travelling salesman problem that something many PhD years have been spent on in a matter of hours? (OK fine. They are PhD years but the question is still valid.)

Anyway, I’m not buying it. If you are so great at coming up with efficient networks, why don’t you plan our cities for us? Oh, what is that? You tried it[7] and it’s too basic a problem for the great shuttle-streaming, efficient-network-solving, many-headed slime? Fuck you. (Because, like the rest of us, you have membrane bound organelles and all that jazz which makes conjugation hard and you have to exchange genetic material the normal eukaryotic way.) Doubt all the sequencing in the world is going to tell us how you do what you do but thought we’d try anyway.

All of this we might have been able to live with. But then you go all topology on our ass and solve mazes[5]. WHY? Do you think you’re Euler or something? You change your shape to cover the shortest distance between food sources no matter the obstacles we place in your path[5]. Seriously, is there no end to how you can belittle our intelligence?

So, in conclusion, please stop blowing our highly evolved thinking minds… Perhaps keep yourself busy trying to figure out how many possible mazes exist and then solving them all or some other such obscure classification theory problem. Also, while you are at it, we are very confused by what a protist is, so please let us know if you have any thoughts on that classification front as well.

References

  1. Anderson JD. Galvanotaxis of slime mold. J Gen Physiol. 1951 Sep;35(1):1-16.
  2. Block I, Rabien H, Ivanova K. Involvement of the second messenger cAMP in gravity-signal transduction in Physarum. Adv Space Res. 1998;21(8-9):1311-4.
  3. Kamiya N. Physical and Chemical basis for Cytoplasmic Streaming. Ann. Re.. Plant PhysioL 1981. 32:205-36.
  4. Kuroda R, Kuroda H. Relation of cytoplasmic calcium to contractility in Physarum polycephalum. J Cell Sci. 1982 Feb;53:37-48.
  5. Nakagaki T, Yamada H, Toth A. Maze-solving by an amoeboid organism. Nature. 2000 Sep 28;407(6803):470.
  6. Nakagaki T, Yamada H, Hara M. Smart network solutions in an amoeboid organism. Biophys Chem. 2004 Jan 1;107(1):1-5.
  7. Tero A, Takagi S, Saigusa T, Ito K, Bebber DP, Fricker MD, Yumiki K, Kobayashi R, Nakagaki T. Rules for biologically inspired adaptive network design. Science. 2010 Jan 22;327(5964):439-42. doi: 10.1126/science.1177894.
  8. Saigusa T1, Tero A, Nakagaki T, Kuramoto Y. Epub 2008 Jan 3. Amoebae anticipate periodic events. Phys Rev Lett. 2008 Jan 11;100(1):018101.
  9. Smith DA, Saldana R. Model of the Ca2+ oscillator for shuttle streaming in Physarum polycephalum. Biophys J. 1992 Feb;61(2):368-80.
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