The primary cilium is an important sensory signaling hub, roughly comparable to a single bacterium, found in many cells in our bodies. Classic textbooks portray this structure in the shape of an antenna, sticking out like a sore thumb and surrounded by the cell landscape. However, if you look at it a bit more closely, it turns out that it is not just a simple cylindrical lozenge. Some cilium are curved. Others are kinked. And oddly, a few are bulging near the tip! Recent studies have shown that perturbed expression of certain proteins can cause defects in both the function and overall shape of the primary cilium, which can lead to a myriad of human diseases termed “ciliopathies.” However, it is still a challenging problem to obtain a clear picture of this small, crowded organelle in its natural habitat and in a non-invasive, precise manner.

The cover image for the January 22 issue of the Biophysical Journal shows the surface mesh of a primary cilium. The color of the mesh represents how far away the surface is relative to the reader. Using a combination of superresolution fluorescence microscopy and quantitative methods, we now have a framework for answering questions related to the shape of the primary cilium surface. Parameters such as diameter, surface area, and curvature are now measurable quantities which can inform us about overall changes at the nanoscale level. One could imagine applying this method to other tiny biological systems of interest, such as organelles, membrane tubules, or bacteria.

Our hope is that our study and cover image inspire others to take the step of adding new tools such as 3D superresolution microscopy and image analysis to gain a better understanding of what they’re observing. Sometimes the solution to a problem can come from the place we’d least expect.

If you’re still curious about the other work we do, check out the Moerner lab research page!

- Joshua Yoon, Colin J. Comerci, Lucien E. Weiss, Ljiljana Milenkovic, Tim Stearns, W. E. Moerner