What was Wells' idea? Well, he thinks that centrioles look like turbines. So he thinks maybe they are turbines. And so maybe they rotate around each other, just at the right moment during cell division, and create an oscillation in all those microtubules, thereby generating a vortex that drives the polar ejection force. And maybe that rotation is regulated by calcium. That's the Rivista paper in a nutshell.
The ideas are testable, and plausible to the extent that they don't invoke functions or phenomena from way far out. But they aren't based on any data. There are no observations that even suggest that centrioles rotate (and Wells postulates rotation rates of up to 10,000/second), nor have microtubules been seen to exhibit the vortex-like oscillations that Wells' hypothesis predicts. And most importantly, the polar ejection force is not known to affect anything other than chromosomes. But Wells' hypothesis predicts a "wind" blowing into the center of the cell, a wind that would exert force on every particle between the two poles. In other words, even when the paper was published, its ideas came out of left field.
I doubt that the paper has ever been cited by another cell biologist. No one has published any observations to suggest that centrioles rotate or that a vortex is induced in a dividing animal cell. A proof-of-principle experiment would have been technically challenging but perfectly feasible, if a little expensive. (Here's one idea: use video microscopy to look for movement of inert particles, perhaps fluorescent beads, inside the postulated vortex of the mitotic spindle.) Whether Wells ever tested his hypothesis (or whether he meant to), I don't know.
But now, in 2007, there's no need. Two different lines of evidence make Wells' hypothesis unworthy of further consideration.
Either one of those results would have killed the idea.
- Largely normal chromosome behavior, and the polar ejection force, can occur in animals that completely lack centrioles.
- The properties of a particular chromokinesin appear to completely account for the polar ejection force.
Monday, December 03, 2007
Steve Matheson has a nice post showing just how seriously biologists take one of the extremely rare examples of peer-reviewed papers published by 'senior' fellows at the Discovery Institute: