Microtubules and Ca2+-sequestering membranes in the mitotic apparatus, isolated by a new method.
The mitotic apparatus of sea urchin embryos was isolated using a polyethylene glycol (PEG)/EGTA-medium. Such a procedure preserves the birefringence and the Ca2+ lability of the isolated mitotic apparatus. The method of isolation gives good preservation of the microtubules and of the intracellular Ca2+-transport system as visualized by a monoclonal antibody to a 46-kDa protein. Triple fluorescence studies allow a comparison of the relative locations of microtubules, Ca2+-sequestering membranes and chromatin (by Hoechst 33342) in the mitotic apparatus. We find that the Ca2+-sequestering membranes are concentrated mainly in the centers of the asters and do not follow the distribution of microtubules in the mitotic apparatus. Regulation of microtubules by Ca2+ may not depend on immediate contiguity of microtubules and the Ca2+-regulating sites.
Petzelt
C
C
Institute of Cell and Tumor Biology, German Cancer Research Center, Heidelberg, Federal Republic of Germany.
Hafner
M
M
Mazia
D
D
Sawin
K W
KW
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002458:Cell Fractionation; D008297:Male; D008870:Microtubules / Q000378:metabolism / Q000648:ultrastructure*; D008938:Mitosis; D010063:Ovum / Q000378:metabolism / Q000648:ultrastructure*; D012617:Sea Urchins; D013094:Spermatozoa; D008941:Spindle Apparatus / Q000378:metabolism / Q000648:ultrastructure*
D002118:Calcium