Figure 6.

Inhibition of Ca²⁺infux and of PKC activity delayed gastrulation, but not PMC ingression. (A) P. lividus embryos were treated with 25 μM GdCl₃ for 50 min starting from 15 min before the 2nd, 4th, 5th and 7th cleavages at room temperature. Cell cycles went on every 30–35 min. Control and GdCl₃-treated embryos were both fixed at the same time, and the percentage of PMC-ingressed embryos or gastrulation-initiated embryos were calculated from circa 100 embryos from two or three independent experiments, respectively. (B, C) H. pulcherrimus embryos were treated with HpPKC-I at 6 μM (B) or 5 μM (C) during the period indicated by the horizontal bars. Gastrulation levels were estimated only from the side-viewed embryos. Embryos were cultured at 15°C (B), at 18°C (C). The cell cycles of these experiments were 45–48 min (B) and 39 min (C).