Figure 6.

H1 nuclei replicate when diluted with fresh extract if fresh extract lacks H1 and dilution occurs before nuclear envelope assembly. Sperm chromatin was incubated in extract supplemented with [α-³²P]dATP and Ara-CTP either without H1 (lane a) or with H1 (lanes b, c, and d) for 20 (lane c) or 60 min (lanes a, b, and d). Four volumes of fresh extract supplemented with [α-³²P]dATP and Ara-CTP either without H1 (lanes a, c, and d) or with H1 (lane b) were then added. By 90 min, all samples were released from Ara-CTP arrest with dCTP and incubated for an additional 50 min. DNA replication is expressed as a percentage of the control sample (lane a).