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DNase I-sensitive sites within the nuclear architecture visualized by immunoelectron microscopy
1Laboratoire de Biologie Cellulaire et Tissulaire, Université de Liège, Belgium.
DNA and Cell Biology
|April 1, 1991
Summary
This study visualizes active gene regions in cells using electron microscopy and DNase I nick-translation. It reveals the distribution of sensitive chromatin, offering new insights into cellular and nucleolar organization.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Nick-translation with DNase I preferentially labels active genes.
- Adapting this technique to electron microscopy allows in situ visualization of DNase I-sensitive chromatin regions.
Purpose of the Study:
- To visualize DNase I-sensitive chromatin regions in Ehrlich tumor cells using electron microscopy.
- To investigate the functional organization of chromatin and nucleoli within intact cells.
Main Methods:
- Electron microscopy combined with DNase I nick-translation.
- Treatment of cells with varying DNase I concentrations and actinomycin D.
Main Results:
- In interphase cells, labeled sequences appear near condensed chromatin blocks.
- Higher DNase I concentrations or longer incubation are needed to label condensed chromatin.
- In the nucleolus, fibrillar centers and surrounding interstices are labeled first, not the dense fibrillar component.
- Actinomycin D pretreatment reduces labeling of perinucleolar chromatin clumps.
Conclusions:
- This method provides a novel tool for studying chromatin functional organization in situ.
- The observed labeling patterns in nucleolar components may challenge existing models of nucleolar organization.