Control of histone gene expression in Physarum polycephalum. I. Protein synthesis during the cell cycle.
Synchronous cultures of Physarum polycephalum were pulsed with [3H]lysine hydrochloride in S and G2 phases of the cell cycle. Plasmodial extracts were separated into nuclear, ribosomal and acid-soluble post-ribosomal cytoplasmic fractions. Core histones could be detected by staining in the nuclear fractions of both S and G2 phases, but were not detected by staining in the cytoplasmic fractions. Newly synthesized histone was present in S-phase nuclei but not in S-phase cytoplasm. The specific activity of newly synthesized histone in G2-phase nuclei decreased by at least 95% compared to S phase and no newly synthesized histone was observed in G2-phase cytoplasmic fractions. Thus histone synthesis is restricted to S phase. There are no free pools of histone in the cytoplasm of Physarum in either S or G2 phases of the cell cycle.
D002453:Cell Cycle; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D006657:Histones / Q000096:biosynthesis*; D007399:Interphase; D010804:Physarum / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
D006657:Histones