Field of Science

Sunday Protist - Streblomastix: intestinal torpedo-bearing sub

ResearchBlogging.orgTaking a bit of a break from Rhizaria... haven't done Excavates in a while. From one obscure 'kingdom' to another... (although now I have this nagging feeling that I'm really neglecting unikonts - I haven't done amoebozoa or opisthokonts in ages...)

And the creature behind (or rather, containing) Mystery Micrograph #01 is...

(Leander & Keeling 2004 J Euk Microbiol; scalebar=5μm)
Streblomastix strix, an oxymonad. 2 - cross-section

Rosie more or less got this one ^.^ (I guess one can't really expect a sane person non-protistophile to randomly pass by and yell out OMG STREBLOMASTIX!!1!) It's a thing with several extremely long episymbiotic bacteria riding along it, kinda like torpedoes, so the 'eukaryote with bacterial symbionts' was right!

I won't go into detail about oxymonads, since Opisthokont knows a few orders of magnitude more about them than I can pretend to. Perhaps he'd like to contribute some. [/hint] Essentially they are an anaerobic, amitochondriate lineage of mostly termite/cockroach gut endosymbionts. For some reason, most of those gut endosymbiont protists tend to gather entire bacterial worlds around (and inside!) them. Perhaps due to the closed, small nature of the ecosystem, where there is time for various prokaryotes to coevolve with the protists and become closely associated without too much outside disturbance. These protists have been living with termites and cockroaches at least since the early Cretaceous (Poinar 2009 Parasit Vectors), so there's been plenty of time for entire phyla to be borne of this relationship.

Oh, apparently there's such thing as hunting around for termite endosymbionts in amber! Couldn't find any of Streblomastix, but here's a ~100 x 106 year old relative, Dinenymphites:

(Poinar 2009 Parasites & Vectors; open access)

That paper is rather fascinating! And this is from someone who's not much of a paleontology nut. Anyway, back to Streblomastix.

An interesting question is, what are those bacteria doing? The cell structure seems adapted for episymbiosis, complete with specialised attachment sites. Sure enough, killing off the bacteria with antibiotics results in the eukaryote's imminent death (Leander & Keeling 2004 JEM). The specifics of the relationship still remain poorly understood, it seems. There's also even more elusive intracellular bacteria. Basically if you look at an animal or plant carefully enough, you'll find entire ecosystems of protists and prokaryotes. If you look at a protist carefully enough, chances are there'll be an entire bacterial ecosystem in its own right...but I digress.

Leander & Keeling 2004 J Euk Microbiol; m1-3 - three distinct morphotypes of bacteria, scalebar=0.5um; 16 - TEM cross section of a 'vane' tip with arrows showing the glycocalyx-like connections between bacteria and the host. 17 - posterior tip of Streblomastix showing the 'cupping' of the final bacterium.

Actually, a winged termite (Zootermopsis!) had the great misfortune of appearing before my face yesterday. This is a sample of the result:

Yes, the shittiest picture of Streblomastix in the history of termite gut microscopy. I tried to get the flagella in focus, but the whole cell is pretty mangled. The Trichonymphas turned out better, but barely... Sigh, I really need Trager medium... and access to a camera that is not too slow even for plants. I guess that means no colour CCD, since those tend to need a lot of light, and therefore a much longer exposure. Although there must be fast colour cameras too...

(still must redeem self:

Trichonympha. Happy? More termite gut imagery to follow later...)

Ok, it's getting late, I think I'm getting a cold of sorts (I wish it'd make up its mind already, whether it feels like showing up or not. And please, let it be finished before I visit the parents. Mothers + cold = overreaction x 1000!!!) and I'm just gonna have to leave this post in a half-sucky state. Did any of it make sense?

As for the next major topic, it'll be the origins of Eukarya and the Neomuran Hypothesis, with plenty of famously clear and comprehensible diagrams by the God of Protistology. Also, there's a recent Science article by Carl Zimmer that awaits a bit of gentle shredding. Actually, I'll wait until Rosie's reply to his sex article is published next week =D But prior to Neomura, there is a massive rant in store. Evolutionary directionality is GOING DOWN! Mwahaha...

And as for ye who foolishly voted 'cheese!' in the poll - watch out! It's coming...
LEANDER, B., & KEELING, P. (2004). Symbiotic Innovation in the Oxymonad Streblomastix strix The Journal of Eukaryotic Microbiology, 51 (3), 291-300 DOI: 10.1111/j.1550-7408.2004.tb00569.x

Poinar GO (2009). Description of an early Cretaceous termite (Isoptera: Kalotermitidae) and its associated intestinal protozoa, with comments on their co-evolution Parasites and Vectors, 2 : 10.1186/1756-3305-2-12


  1. Fossil protists! Fantastic. And the author is at Oregon State, too! Not my alma mater, but since I no longer live in Portland I will happily get behind anything good from that fine state....

    A couple of quick comments on your own microscopy. First, your Trichonympha is pretty good, actually. In my experience, they swell up and explode less than an hour after exposure to oxygen, and getting a recognisable image of one that healthy is an achievement. They really are amazing to watch, too, sort of like slow-motion ciliates.

    Second, you can get by just fine without Trager's solution. Cleveland used a 0.4% solution of sodium chloride, and that produces comparable results: at least, things from Cryptocercus do not last significantly longer in Trager's than in the NaCl solution. Trager's is not a very complicated solution anyway.

    It is great to see oxymonads get some attention! I see that I have been prodded to provide more, but I will have to get to that another time... and having my blog linked means that I really should get more posts up... soon, I promise!

  2. Are those . . . bacterial docking sites in the Leander and Keeling photo? Incredible! Is this protistology or Deep Space 9?

  3. Opisthokont - thanks for the advice! I was mounting the suckers in 5% glycerol because that's what I saw lying around on the microscopy bench. Glycerol seems to have some trippy side effects under polarised light though, do you happen to know what that's all about? Like, twirling the Wallerston/Nomarki prism and the analyser has never been so much fun as with glycerol in the slide! (I'll show off more optical experimentation later...)

    Needless to say, they died pretty much instantly. =( I had clumps and clumps of dead Trichonymphas. It was very sad. They do get to go to Trichonympha heaven after, don't they? The magical eternally-woodful infinite termite gut in the sky? Cornucopia of gut endosymbionts, sounds like my kind of heaven...

    And yeah, update your damn blog. Srsly. I'm almost all alone in writing about protists here, and I'm not even a 'licensed' protistologist!

    Jen - How about bacteria used for motility? That propel the host? Mixotricha paradoxa. I REALLY REALLY need to know how the hell that mechanism works on a cellular level...


Markup Key:
- <b>bold</b> = bold
- <i>italic</i> = italic
- <a href="">FoS</a> = FoS