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Revealing nucleolar architecture by low ionic strength treatment
P Hozák1, G Géraud, D Hernandez-Verdun
1Institut Jacques Monod, Paris, France.
Experimental Cell Research
|November 1, 1992
Summary
This study reveals the internal nucleolar architecture of HeLa cells using hypotonic treatment. Fibrillar centers form the core of nucleoli, supporting RNA-polymerase I complexes.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The nucleolus is a dynamic nuclear subcompartment involved in ribosome biogenesis.
- Understanding the internal organization of the nucleolus is crucial for deciphering its functions.
Purpose of the Study:
- To investigate the internal nucleolar architecture and the response of nucleoli to changes in ionic strength.
- To identify the core structural elements of the nucleolus.
Main Methods:
- Hypotonic treatment of HeLa cells.
- Immunofluorescence and confocal microscopy using monospecific human autoimmune sera.
- Electron microscopy.
Main Results:
- Nucleoli showed differential sensitivity to reduced ionic strength.
- The granular component dispersed first, followed by the dense fibrillar component.
- Distinct fibrillar centers remained, suggesting they are core nucleolar structures.
Conclusions:
- Fibrillar centers provide structural support for RNA-polymerase I complexes.
- Fibrillar centers are likely attached to the nuclear skeleton.
- Functional nucleoli appear to organize around fibrillar centers.