I swear I didn’t put J up to this. But y’all. What if I’m raising a chemist?! 🙈
#physicistMom

Overall, we hypothesize a multi-scale model that can explain Spirostomum contraction from the molecular (nanometer) to the organismal (millimeter) scale.

Not only is this mechanism unusual (and plain cool!), it gives us a new blueprint to control or even synthetically actuate contractility. 12/13

Then we zoomed in some more by electron microscopy. We found that myonemes in elongated cells have clearly detectable sub-structure, which looks like a nanoscale mesh of filaments. In contracted cells, the myoneme is denser and the organized structure has disappeared. 9/13

We found from modeling that the fishnet mesh shape is likely very important for Spiro to contract while maintaining its overall shape. With the fishnet mesh, we can robustly recapitulate the shape changes we observe experimentally. Without the fishnet, in silico cells make super weird shapes. 8/13

Previously identified structures called 'myonemes' cover the cortex of Spiro and contain (at least) two proteins, centrin and Sfi1. We noticed that these myonemes tile the surface of the organism with a fishnet-mesh of parallelograms that change aspect ratio when the organism contracts. 7/13

So first, meet Spirostomum (aka 'Spiro'). This little critter is ONE CELL but nearly a millimeter long (you can see it by eye!). It's easy to find in a pond near you.

Why do we care about it?

It can contract it's body by around three-fold in <5 ms - 10x faster than actomyosin contraction! 3/13