Differential synthesis of histone H1 during early spherulation in Physarum polycephalum.
H1 and P2 (an H1 degree/HMG-like protein) accumulate during exponential growth of Physarum microplasmodia (unpublished results), indicating that these proteins may play a role in differentiation (spherulation). To test this hypothesis, pulse labelling using [14C]lysine was used to determine whether any differential histone synthesis occurs during salts-induced spherulation. A peak in the uptake of [14C]lysine into microplasmodia was detected between 12 and 24 h following salts-induction. During the same interval, incorporation of label into the CaCl2-extracted histones occurred, with H1 being synthesised at approx. 3 times the level of the core histones and P2. Densitometry of SDS-PAGE gels showed that high levels of H1 were maintained up to 40 h in salts medium, beyond the observed peak in synthesis. The synthesis and accumulation of high levels of H1 during early spherulation indicates a role for this histone in the initiation and maintenance of a transcriptionally inactive differentiated state.
Heads
R J
RJ
Biophysics Section, School of Biological Sciences, Portsmouth Polytechnic, U.K.
Carpenter
B G
BG
D000596:Amino Acids / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D015180:Electrophoresis, Gel, Two-Dimensional; D006657:Histones / Q000096:biosynthesis*; D007700:Kinetics; D008239:Lysine / Q000378:metabolism; D010804:Physarum / Q000254:growth & development* / Q000378:metabolism; D014176:Protein Biosynthesis; D012492:Salts / Q000494:pharmacology
D000596:Amino Acids; D006657:Histones; D012492:Salts; D004247:DNA; D003513:Cycloheximide; D008239:Lysine