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The bending rigidity of mitotic chromosomes
Michael G Poirier1, Sertac Eroglu, John F Marko
1Department of Physics, The University of Illinois at Chicago, Chicago, Illinois 60607, USA. mpoirier@safarsquid.phy.uic.edu
Molecular Biology of the Cell
|June 12, 2002
Summary
Researchers measured the bending rigidity and stretching elasticity of newt and Xenopus chromosomes. Results suggest chromosomes have a homogeneous internal structure, not a stiff central core, impacting models of mitotic chromosome organization.
Area of Science:
- Cell Biology
- Biophysics
- Molecular Biology
Background:
- Mitotic chromosomes possess complex higher-order structures essential for accurate cell division.
- Understanding chromosome mechanics provides insights into genome stability and organization.
Purpose of the Study:
- To measure the bending rigidity and stretching elasticity of isolated and in vivo mitotic chromosomes.
- To use mechanical properties to infer the internal structural organization of chromosomes.
Main Methods:
- Measurement of spontaneous thermal bending fluctuations to determine bending rigidity (B).
- Simultaneous measurement of stretching (Young's) modulus (Y).
- Analysis of mechanical data in the context of elastic rod models.
Main Results:
- Bending rigidity values were approximately 10(-22) N. m(2) for newt and 10(-23) N. m(2) for Xenopus chromosomes.
- Stretching modulus ranged from 10(2) to 10(3) Pa for both species.
- Measured properties align with a homogeneous elastic rod model (B ≈ YR(4)).
Conclusions:
- Chromosome mechanical properties are inconsistent with a stiff central core model.
- Results support a model of internal chromosome structure that is homogeneous across the cross-section.
- These findings refine models of higher-order mitotic chromosome structure and mechanics.