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primary cilia of mouse IMCD (Inner Medullary Collecting Duct) cells
How small primary cilia are?
How small primary cilia are?
How small do you think a primary cilium is?
It’s a micro-sized orgenlle, but how tiny?
A primary cilium occupies only a nanoscopic fraction of the cell, creating a remarkably small compartment compared with the surrounding cytosol.
But here’s the surprising part:
A tiny volume means that you don’t need many ions to change the electrical environment.
In the cytosol, moving a few ions barely changes the overall concentration. In a cilium, the same number of ions can have a much larger effect because they are confined to such a small volume.
That means a handful of ions can matter. A cilium may be tiny in size, but its small volume gives ion movements the potential to create surprisingly large local changes.
Small compartment. Small number of ions. Big consequences.
Explore the difference in volume between a primary cilium and the cytosol and see just how little space a cilium has to work with. Play the simulation below!
▶ Play the simulation at https://dajiha.github.io/cilium-nanodomain-simulation-/cilium-nanodomain.html
Why do you think primary cilia house Ion channel?
Why do you think primary cilia house Ion channel?
Ciliary patch clamp image
Primary cilia are tiny, highly specialized compartments that extend from the cell surface.
And yet, they are packed with ion channels. Why?
What could a cell possibly gain by putting ion channels in a compartment this small?
Because size changes everything.
When ions enter a tiny compartment, they are not diluted into the enormous volume of the cytosol. Even a small movement of ions can rapidly change the local chemical and electrical environment.
Could this be the point?
Perhaps the small volume of the cilium allows cells to turn the movement of just a few ions into a powerful local signal.
A tiny compartment. A few ions. A surprisingly big signal.
So the question becomes:
Can a handful of ions become a signal? Also, Is a primary cilium electrically connected to the cell or electrically distinct?
To tackle these fundamental questions, we perform ciliary electrophysiology and imaging experiment. Also, we are developing optogenetic tools to visualize ciliary ion channel activity.
▶ Play the simulation to calculate the ciliary resting membrane potential
https://dajiha.github.io/cilia-resting-potential.1/cilium-resting-potential.html
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