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I’m in Boston this weekend for the annual Biophysical Society Meeting and I just got out of the session on motility. There were two great talks on the microtubule associated proteins dyneine and kinesin, something I’m interested in from my work with Igor [pdf].
The first was a very thorough talk from Arne Gennerich, who is currently setting up his lab at the Albert Einstein College of Medicine (as he pointed out at the end of his talk, postdoc positions are available!). He used optical trapping to probe the force-dependent stepping behaviour of single dyneines. At zero force, dyneine can take many steps in a row in one direction along a microtubule usually advancing about 8 nm per step. One of their interesting results was that the number of large (~24 nm) steps actually increases when a rearward force is applied to the motor. This may be due to a force-induced unstacking of the two legs that frees them to take longer steps. For details you can check out their paper in Cell from 2007 [pdf].
Another nice talk was from Stefan Diez at the Max Planck Institute for Molecular Cell Biology and Genetics in Dresden. 
They used some modern microfabrication and microscopy techniques to squeeze out more interesting results from a microtubule gliding assay. I love these gliding movies anyway, but they really look cool with some of the Diez group’s embellishments:
I’ll be at the meeting until Wednesday, so stay tuned for more. If you’re in the Boston area and want to meet just drop me an e-mail.
Biocurious is written by Andre Brown and Philip Johnson, since 2005. Content of the weblog is licensed under a Creative Commons Attribution-Share Alike 3.0 License.
Interesting! I just finished speaking on the phone to my husband who is there, and he was telling me about the great dynein work that is being reported.
Which, exactly, are the embellishments?
The dynein result may help explain something that happens in mitosis and meiosis. The spindle fibers (tubulin based) pull on the chromosome pairs only when there is an opposing force (another fiber pulling in the opposite direction). Otherwise they let go.
This is a clever solution to the problem of making sure each pair has one fiber pulling in each direction, rather than two pulling in the same direction.
Phil, they do several kinds of embellishments. I linked to that movie just because it was a nice looking example from their group site, I don’t think he spoke about that work specifically. One example he spoke about was attaching quantum dots to the microtubules and using FLIC microscopy to measure the quantum dots’ height above the surface. They used it to visualize the rotation of the filaments and how that was different for different motors. They also did some single motor and double motor stuff that’s hard to explain in words, but involves the microtubules sweeping out arcs in the image plane that become lines when a second motor binds. That way they can study the cooperative effects of exactly two motors on one microtubule. That’s interesting because of the cooperativity that may be involved in cargo transport.