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Updated: Aug 11, 2026

A Filtration-based Method of Preparing High-quality Nuclei from Cross-linked Skeletal Muscle for Chromatin Immunoprecipitation
Published on: July 6, 2017
Ultrastructural study of chromatin fibrils in thin sections of isolated nuclei
Abstract:
In ultrathin sections of isolated rat liver nuclei and chromatin fibril represents a chain of 250-A globules. Electron microscopic examination of the physiologically loose globules of diffuse chromatin or globules of compact chromatin loosened by heparin treatment has revealed that each 250-A globule contains a nucleosome covered with 60--85-A thick layer -- "a capsule of a nucleosome". Some filaments, approximately 20 A in diameter, can be distinguished within the capsule each being attached to the nucleosome by a dark granule. Chromatin fibril has an axis representing "beads-on-a-string" -- a chain of nucleosomes interconnected with 25-A thick filaments. Some implications of the capsule molecular composition and of its role in transcription are suggested. A model of 250 A chromatin globule as well as of chromatin fibril, different from either the solenoid model or the superbead one is put forward.
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