DOI: 10.1126/science.1086560. The Distribution of Active Force Generators Controls Mitotic Spindle Position

The Distribution of Active Force Generators Controls Mitotic Spindle Position

10.1126/science.1086560

Crossref journal-article

American Association for the Advancement of Science (AAAS)

Science (221)

Abstract

During unequal cell divisions a mitotic spindle is eccentrically positioned before cell cleavage. To determine the basis of the net force imbalance that causes spindle displacement in one-cell Caenorhabditis elegans embryos, we fragmented centrosomes with an ultraviolet laser. Analysis of the mean and variance of fragment speeds suggests that the force imbalance is due to a larger number of force generators pulling on astral microtubules of the posterior aster relative to the anterior aster. Moreover, activation of heterotrimeric guanine nucleotide– binding protein (Gprotein) α subunits is required to generate these astral forces.

Bibliography

Grill, S. W., Howard, J., SchaÌffer, E., Stelzer, E. H. K., & Hyman, A. A. (2003). The Distribution of Active Force Generators Controls Mitotic Spindle Position. Science, 301(5632), 518â521.

Authors 5

Stephan W. Grill (first)
Jonathon Howard (additional)
Erik Schäffer (additional)
Ernst H. K. Stelzer (additional)
Anthony A. Hyman (additional)

References 32 Referenced 335

10.1016/0092-8674(92)90468-R
10.1016/S0074-7696(08)60059-5
K. J. Kemphues, S. Strome, in C. elegans II, D. L. Riddle, T. Blumenthal, B. J. Meyer, J. R. Priess, Eds. (Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, 1997), pp. 335–359. / C. elegans II, (1997)
10.1016/S1534-5807(02)00226-5
10.1126/science.1072162
10.1016/S0960-9822(02)01355-6
10.1016/0012-1606(84)90117-9
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10.1038/35024000
10.1016/S0962-8924(02)02306-1
10.1038/35050656
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10.1038/nature01600
See supporting data on Science Online.
10.1083/jcb.200209079
10.1038/270265a0
10.1113/jphysiol.1980.sp013426
D. Schmidt S. Strome unpublished data.
10.1016/S0955-0674(01)00292-7
In the velocity-limited regime a fragment moves at the maximum velocity whenever there are one or more force generators active. The more force generators per fragment the higher the mean speed because the probability of having at least one active force generator is increased. However this model results in a mean-variance relationship identical to the force-limited case presented with N = 1. This is not consistent with our results.
With fewer than 12 aster fragments generated per spindle pole and one or two active force generators per fragment we expect fewer than 50 active force generators throughout the embryo at any time during anaphase.
10.1038/35060092
10.1016/S0092-8674(02)01170-4
10.1038/35042526
10.1126/science.1084146
10.1016/S0960-9822(03)00371-3
10.1101/gad.1081203
10.1083/jcb.200202047
Because the laser was focused at regions where the pericentriolar material and γ-tubulin are localized we expect a fraction of the centrosomal γ-tubulin to be destroyed. Consequently not all aster fragments contained detectable levels of γ-tubulin.
L. Sachs Applied Statistics: A Handbook of Techniques (Springer New York 1984). (10.1007/978-1-4612-5246-7)
Stray light from the pulsed ultraviolet (UV) laser used for OICD bleached the surrounding GFP–α-tubulin. Therefore UV laser power was reduced by about 70% to visualize fragment movement by GFP. With less laser power we probably produced larger fragments with an increased drag coefficient. Thus elementary speeds were smaller in the GFP assay than in the DIC assay. On the other hand larger fragments have more force generators associated consistent with the general increase in N for the GFP assay.
We thank C. Cowan A. Desai M. Diehl P. Gönczy M. Glotzer E. Hannak F. Jülicher K. Oegema L. Pelletier A. Riedinger G. Ritter E. Sackmann N. Salmon M. Srayko and E. Tanaka for useful discussions experimental assistance and helpful comments. Supported by Deutsche Forschungsgemeinschaft grant SPP 1111 (HY3/2-1).

Dates

Type	When
Created	22 years, 1 month ago (July 24, 2003, 3:56 p.m.)
Deposited	1 year, 7 months ago (Jan. 9, 2024, 9:40 p.m.)
Indexed	1 week, 6 days ago (Aug. 21, 2025, 1:59 p.m.)
Issued	22 years, 1 month ago (July 25, 2003)
Published	22 years, 1 month ago (July 25, 2003)
Published Print	22 years, 1 month ago (July 25, 2003)

Funders 0

None

BibTeX

@article{Grill_2003, title={The Distribution of Active Force Generators Controls Mitotic Spindle Position}, volume={301}, ISSN={1095-9203}, url={http://dx.doi.org/10.1126/science.1086560}, DOI={10.1126/science.1086560}, number={5632}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Grill, Stephan W. and Howard, Jonathon and Schäffer, Erik and Stelzer, Ernst H. K. and Hyman, Anthony A.}, year={2003}, month=jul, pages={518–521} }

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