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Core filaments of the nuclear matrix
D C He1, J A Nickerson, S Penman
1Department of Biology, Beijing Normal University, Peoples Republic of China.
The Journal of Cell Biology
|March 1, 1990
Summary
Researchers isolated nuclear matrix core filaments using DNase I and stepwise salt extraction. These filaments, crucial for nuclear structure, retain significant nuclear RNA, including precursors and hnRNA.
Area of Science:
- Molecular and Cell Biology
- Biochemistry
- Genetics
Background:
- The nuclear matrix, essential for nuclear organization, is obscured by abundant chromatin.
- Understanding the nuclear matrix structure requires effective methods to remove chromatin while preserving matrix integrity.
Purpose of the Study:
- To characterize the structural components of the nuclear matrix.
- To investigate the role of core filaments in nuclear structure and RNA retention.
Main Methods:
- Selective chromatin digestion using DNase I.
- Chromatin elution with 0.25 M ammonium sulfate.
- Further nuclear matrix extraction with 2 M sodium chloride to reveal core filaments.
Main Results:
- A mild procedure effectively removed chromatin, preserving nuclear matrix morphology.
- Extraction revealed a core filament network (9-13 nm diameter) within the nuclear matrix.
- Core filaments retained 70% of nuclear RNA, including rRNA precursors and high molecular weight hnRNA (modal size 20 kb).
Conclusions:
- The nuclear matrix contains a core filament network potentially serving as a structural scaffold.
- These core filaments play a significant role in retaining nuclear RNA.
- Stepwise ionic strength increase is critical for uncovering the nuclear matrix core filament structure.