Effects of U0126 or ML-7 treatment in metaphase II eggs. Metaphase II eggs were
treated with 0.5% DMSO (A), 15 μM ML-7 (B), or 50 μM U0126
(C) for 3 h, then fixed and stained with DAPI to label DNA,
anti-β-tubulin to label the meiotic spindle, and the monoclonal antibody MPM-2 to
label mitotic phosphoproteins (analysis shown in Fig.
5). Eggs were classified as metaphase II (Met II; normal metaphase II spindle
morphology and cortical localization), Met II drifted spindle (i.e., the DNA was
aligned along the metaphase II plate and the spindle was greater than 12 μm from the
cortex; shown in Fig. 2), anaphase II, or
telophase II (Ana II and Telo II, respectively, i.e., progressing out of metaphase II
arrest). Numbers in or above bars indicates numbers of eggs analyzed. The extent of
progression out of metaphase II arrest (combined numbers of eggs in anaphase II and
telophase II states) in U0126- and ML-7-treated eggs is statistically significant as
compared to DMSO-treated eggs (chi-square analysis, *P < 0.0001).
The extent of drifted spindle incidences in U0126- and ML-7-treated eggs is
statistically significant as compared to DMSO-treated eggs (chi-square analysis,
**P < 0.0001).