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. 1975 Jul;72(7):2691–2695. doi: 10.1073/pnas.72.7.2691

Chromatin architecture: investigation of a subunit of chromatin by dark field electron microscopy.

J P Langmore, J C Wooley
PMCID: PMC432836  PMID: 1058483

Abstract

Dark field scanning electron microscopy of unstained, unfixed samples of chromatin, histone-1-depleted chromatin, and nucleohistone has been used to identify an apparent subunit of chromatin, namely a disk-shaped structure we term the unit particle, which is probably about 135 A wide and 50 A thick in the hydrated state. The unit particles are found at rather uniform intervals along thin DNA-like fibers. Histone 1 depletion leads to a bimodal distribution of these spacings. Our observations suggest that the unit particle consists of a loop of nucleoprotein, perhaps around a histone core.

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