Depolymerizing microtubules in melanophores

[Brian T. Greuel]

I'm developing a new lab exercise for a cell biology course that illustrates 
microtubule-dependent intracellular motility.  The system I am using is 
pigment granule migration in the melanophores of the marine killifish, 
Fundulus.  I have been trying to get the microtubules to depolymerize by cold 
treatment so that the pigment granules will be released into the cytoplasm, 
but thus far I have been unsuccessful.  Even treatment for several hours at 4 
degrees Celsius fails to induce depolymerization.  Once the microtubules are 
depolymerized, of course, I would monitor their reassembly in the presence or 
absence of various inhibitors, using association with the pigment granules as 
the indicator of reassembly.  My problem though is in disrupting these 
microtubules.

Colchicine treatment alone should not depolymerize the microtubules in these 
cells because they are supposed to be in a "fixed array."  I may just go ahead 
and try it anyway just to confirm this.  Any other ideas about how I can 
depolymerize the microtubules in the melanophores of Fundulus?

Thanks in advance for any help you can provide.  If you could email me 
directly I would be grateful since I do not often monitor this news group.

Brian T. Greuel
Dept. of Biology
University of Scranton
Scranton, PA   18510
email:  greuelb1 at uofs.edu
TEL:  (717) 941-4324