Figure 5.
The intra-S phase checkpoint reduces Cdc45 and PCNA on chromatin.
(A) Sperm nuclei were incubated at 10 ng DNA/μl in interphase extract supplemented with various concentrations of aphidicolin minus (left panel) or plus 5 mM caffeine (right panel). Chromatin was isolated and immunoblotted for XCdc45 and Rad17. (B) Sperm nuclei were incubated at 10 ng DNA/μl in interphase extract supplemented with different combinations of 15 μM aphidicolin and/or 5 mM caffeine. At the indicated times, chromatin was isolated and immunoblotted for XCdc45 and PCNA.