Gliding Diatoms

Mar 28, 2015 • 10:55 AM UTC

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140x Magnification

Microorganisms

Manu Prakash

I am a faculty at Stanford and run the Prakash Lab at Department of Bioengineering at Stanford University. Foldscope community is at the heart of our Frugal Science movement - and I can not tell you how proud I am of this community and grassroots movement. Find our work here: http://prakashlab.stanford.edu

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They twist, they turn… they glide!!
But you ask, what am I talking about here? It’s not Michael Jackson on his moon walk, but it’s no less impressive. I am talking about our dear friends – diatoms – unicellular algae that prefer to live in a glass house. It’s no originate glass house; it’s a spectacular glass house that we don’t really know how they know how to make.. You get the point.
You might imagine if you were trapped inside a tiny little glass house (which is stiff and rigid); you could not move with that entire glass house. But that is what diatoms do – they glide and adhere to surfaces. And the best part, it’s still a mystery how this actually glide on any surface, pretty much like a moon walk.
Here are the videos of diatoms performing a moon walk:

Methods:
1. Go to a pond and pick some pond scum. Anywhere you see a little greenish growth is good enough.
2. Put this “not so pretty” looking stuff on a glass slide and mount a cover slip on top. Since you want to keep some water in the slide, you can seal the slide with nail polish or just some tape.
3. Mount this inside your Foldscope (140X; low mag) and get ready for some fascinating glass structures that still move.
4. I recorded these videos with my iPhone 5 with my magnetic couplers.
You will see multiple diatoms gliding in the videos above. They mostly move in straight lines but suddenly change directions. That’s puzzling; what drives the directionality to begin with and how can they change. They don’t have a head or a tail; so spontaneous symmetry breaking and reversal is fascinating to watch. Are they detecting anything in the environment?
What we know is that the motility is caused by actin-myosin complex. It’s been demonstrated that drugs that inhibit both actin filaments or myosin motors will inhibit mobility; and the mobility can be restored back in 5 seconds by removing the drugs.
For more info on drug pertibations http://www.ncbi.nlm.nih.gov/m/pubmed/10470016/
But that’s not enough to explain how on earth is something that lives inside a glass she’ll capable of gliding along.
Cheers
Manu
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