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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
149
102-POS
Board 51
Microtubules Push Chromosomes Apart in Anaphase
Che-Hang Yu
1
, Stefanie Redemann
2
, Hai-Yin Wu
1
, Tae Yeon Yoo
1
, Thomas Mueller-Reichert
2
,
Daniel Needleman
1
.
1
Harvard University, Cambridge, MA, USA,
2
Technische Universität, Dresden, Germany.
The processes which drive chromosome motion in anaphase are poorly understood and different
mechanisms have been proposed to operate in meiosis and mitosis and in different organisms,
including depolymerization of kinetochore microtubules, pulling apart spindle poles by cortical
pulling forces, and pushing apart spindle poles by the elongation of microtubules which extend
from the pole to the center of the spindle.
We have investigated anaphase in the first mitotic division of C. elegans and found that, contrary
to previous speculations, spindle pole separation and chromosome separation are two
mechanistically distinct processes. We argue that while spindle pole separation is driven by
cortical pulling forces, chromosome separation results from a new population of microtubules
which appear between chromosomes at the onset of anaphase and push chromosomes apart. We
characterized the behaviors of this newly discovered population of microtubules using a
combination of laser ablation, nonlinear microscopy, fluorescence recovery after bleaching,
larger scale electron tomography reconstructions, and mathematical modeling. Our results
suggest that these microtubules continually nucleate in a small region between chromosomes
throughout anaphase, and push chromosomes apart by a combination of polymerization and
sliding. Additional preliminary results indicate that the same processes could be the primary
driver of chromosome motion in anaphase in C. elegans meiosis and in mitotic human tissue
culture cells. Thus, a common underling mechanism may drive chromosome segregation in
anaphase in diverse systems: newly generated microtubules between chromosomes push them
apart.