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The higher order structure of the centromere.
1Department of Medical Biochemistry, Faculty of Medicine, University of Calgary, Alta., Canada.
Genome
|August 1, 1987
Summary
5-azacytidine treatment reveals reversible centromere condensation in mouse chromosomes. This process shows the native centromere forms via helical folding of a 100 nm subfiber, revealing new chromatin organization levels.
Area of Science:
- Cell Biology
- Genetics
- Chromatin Structure
Background:
- Centromere structure is crucial for chromosome segregation.
- Understanding centromere organization provides insights into genome stability.
Purpose of the Study:
- To investigate the higher-order chromatin organization of mouse centromeres.
- To elucidate the structural basis of centromere condensation.
Main Methods:
- Culturing mouse cells with 5-azacytidine to induce centromere elongation.
- Observing reversible condensation using light and electron microscopy (transmission and scanning).
Main Results:
- 5-azacytidine treatment reversibly elongated centromeres.
- Recondensation revealed a helical folding of a ~100 nm subfiber.
- This subfiber is composed of 30 nm fiber loops.
- Final native centromere structure is a homogenous 250-300 nm fiber.
Conclusions:
- Centromere condensation involves hierarchical folding of chromatin fibers.
- A novel level of chromatin organization within metaphase chromosomes is proposed.
- The helical subfiber model explains native centromere morphology.