Tamm, S.L., and Terasaki, M.
Visualization of calcium transients controlling orientation of ciliary beat.
J. Cell Biology 125: 1127-1135 (1994)

We injected the fluorescent Ca indicator Ca Green dextran into 1 or 2 cell stage ctenophore embryos, then let the embryos grow into cydippid larvae (about 2 days). At this point, the cells still had a significant amount of Ca Green dextran in them, so that we had effectively loaded these cells with Ca indicator by this developmental strategy.

The "comb rows" of the larvae consist of many fused cilia. We imaged the fluorescence of the comb rows with a SIT camera and were able to see that the Ca inside the cilia increases at the time of ciliary reversal (i.e., when the cilia changed direction of beating in response to electric stimulation). There had been indirect evidence for a Ca increase in several different organisms but this was the first time that it had been detected directly.

This work is unusual in that the moment of discovery was very well documented. M. Terasaki did the injection, and late the next night, S. Tamm did the experiment with his grad student looking on. We did not really expect this approach to work. In this sound-only movie (225K), you can experience the thrill of a wild shot experiment that actually worked! You can download the complete movie (2200K), but the image quality of the movie is not very good.

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