Characterization of soluble nucleohistone and histone from cotyledons of germinating seeds of Pinus pinea

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Abstract
Soluble nucleohistone and histones have been isolated from cotyledons of P. pinea; this is the first such isolation from any gymnosperm tissue. The nucleohistone isolated was similar in composition and physical characteristics to that of chromatin reported for comparable angiosperm tissues at similar stages of growth. Histones, purified by gel electrophoresis, possessed 8 subfractions which are tentatively identified as follows in order of increasing electrophoretic mobility: very lysine-rich F1 (fractions 1-4), arginine-rich F3 (fraction 5), arginine-rich F2a2 (fraction 6) and F2b (fraction 7), as well as moderately arginine-rich F2a1 (fraction 8). Nucleohistone from days 15-22 of germination, a period of cell elongation in cotyledons, possessed greater amounts of histone, acidic protein, and RNA relative to DNA than day-14 "mitotically active" nucleohistone. Histone acetylation from sodium acetate, methylation from s-adenosyl-L-methionine, and phosphorylation from inorganic phosphate proceeded at low rates in isolated nuclei. Phosphorylation from [32P]ATP occurred to a greater extent; very lysine-rich F1 and arginine-rich F3 histones were phosphorylated to the greatest degree while F2a1 was phosphorylated least.