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CIL:48255*  Cite 

How the cell cytoplasm is spatially organized is of fundamental interest. In ordinary animal cells the cytoplasm is organized by a radial array of microtubules, called an aster. Aster microtubules are nucleated by the centrosome and elongate to the periphery. We investigated how asters grow in an extremely large cell, the frog egg, using microscopy of an extract system. Asters were initially nucleated at centrosomes, but then additional microtubules nucleated far from the centrosome, apparently stimulated by preexisting microtubules. The resulting growth process allows asters to scale to the size of huge egg cells while maintaining a high density of microtubules at the periphery. Microtubule-stimulated microtubule nucleation might be a general principle for organizing large cells.

Technical Details

Fluorescent speckle microscopy shows the outward sliding of microtubules during aster growth. In this condition, dynein motor activity was inhibited by the addition of p150-CC1 protein fragment, resulting in minimal outward microtubule sliding.

Biological Sources
NCBI Organism Classification
Xenopus laevis
Cell Type
Cellular Component
microtubule aster
Biological Context
Biological Process
cell division
Keisuke Ishihara
Phuong A. Nguyen
Aaron C. Groen
Christine M. Field
Timothy J. Mitchison
Digital Object Identifier (DOI)
Archival Resource Key (ARK)
Grouping This image is part of a group.
Image Type
spinning disk confocal microscopy
fluorescent speckle microscopy
Image Mode
Laser excitation of fluorophore
Detection of fluorescence emission
Sample Preparation
live reaction of interphase Xenopus egg extract under a cover slip artificial microtubule organizing center
Low-speed lysate
cytoplasmic fraction