Figure 7.
H1 nuclei do not replicate in H1-free extract that lacks licensing activity. Sperm chromatin was incubated in extract in the presence of [α-32P]dATP and Ara-CTP either without H1 (lanes a and b) or with H1 (lanes c, d, and e) for 20 (lane d) or 60 min (lanes a, b, c, and e). Sperm chromatin (lane d) or nuclei (lanes a, b, c, and e) were then transferred to untreated extract without H1 (lane a), to 6-DMAP extract without H1 (lanes b, d, and e) or to 6-DMAP extract with H1 (lane c), all containing Ara-CTP. After 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).