The use of spermidine for the isolation of nuclei from mouse liver. Studies of purity and yield during different physiological conditions.

A 15 min method for the isolation of clean liver cell nuclei from normal, starved, hepatectomized and sham operated mice in mediums not containing bivalent cations is described. The iso­ lation medium contained 0.5 m M spermidine for stabilization of the nuclear membrane, and macaloid and EDTA for inhibition of RNase activity. The RNA/DNA ratio in normal liver cell nuclei was 0.25 — 0.29 and the protein/DNA ratio 5.2. The RNA/DNA ratio was 0.23—0.25 after starva­ tion for 24 hours and increased to 0.5 at 72 and