Chk1 depletion increases DNA synthesis in the presence of aphidicolin.

<p>(a) Egg extracts were mock- or Chk1-depleted and aliquots analyzed by western blotting using an anti-XChk1 antibody, (b) Sperm nuclei were incubated for 150 min in mock-depleted, Chk1-depleted egg extracts, Chk1-depleted egg extracts supplemented with recombinant 40 nM XChk1 in the presence of [α-³²P]-dATP with or without aphidicolin (5 μg/ml). Nascent DNA strands synthesized after 150 min were analyzed by alkaline gel electrophoresis, (c) Mean replication in mock depleted, Chk1 depleted, Chk1 depleted + Chk1 add back extracts of two independent experiments with SEM (t-tests: mock versus Chk1 depletion: P = 0.026, Chk1 depletion versus add back: P = 0.037), * significantly different (P < 0.05).