J. A. D'Anna, L. Gurley, R. Tobey
Aug 17, 1982
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Influential Citations
38
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Journal
Biochemistry
Abstract
Flow cytometry, conventional autoradiography, and autoradiography employing high concentrations of high specific activity (/sup 3/H)thymidine indicate that (1) treatment of Chinese hamster ovary (line CHO) cells with butyrate truly blocks cells in G/sub 1/ and (2) cells blocked in G/sub 1/ by isoleucine deprivation remain blocked in G/sub 1/ when they are released into complete medium containing butyrate. Measurements of H1/sup o/ content relative to core histones and H1/sup o/:H1 ratios indicate that H1/sup o/ is enhanced somewhat in G/sub 1/ cells arrested by isoleucine deprivation; however, (1) treatment with butyrate greatly increases the H1/sup o/ content in G/sub 1/-blocked cells, and (2) the enhancement is very sensitive to butyrate concentration. Measurements of relative histone contents in the isolated chromatin of synchronized cultures also suggest that the acid-soluble content of histone H1 (relative to core histones) becomes greatly depleted in the isolated chromatin when synchronized cells are blocked in early S phase by sequential use of isoleucine deprivation and hydroxyurea blockade. We also have measured (/sup 3/H)lysine incorporation, various protein ratios, and relative rates of deposition of newly synthesized H1/sup o/, H1, and H4 onto chromatin during G/sub 1/ and S in the absence of butyrate. The results suggest amore » dynamic picture of chromatin organization in which (1) newly synthesized histone H1/sup o/ binds to chromatin during traverse of G/sub 1/ and S phases and (2) histone H1 dissociates from (or becomes loosely bound to) chromatin during prolonged early S-phase block with hydroxyurea.« less