Fig. 2. Myosin IIB is required for morphogenesis at grastrulation. (A) Percentage of Xenopus embryos failing to close the blastopore plotted for 10 µM MHC-B (IIB) MO (n=74), 10 µM control (n=72) and uninjected (n=84) embryos, with s.e.m. (B) Western blots showing MHC-B (IIB), MHC-A (IIA) and actin (Act) levels in uninjected, 5 µM and 10 µM MO, and 10 µM control MO embryos. The normalized ratio of MHC-B or MHC-A to actin (R) is also shown. (C-E) A representative morphant embryo (C), a unilaterally (right-side) morphant embryo (D), and a control embryo (E) at stage 19. (F,G) Time-lapse movie frames showing vegetal (blastopore) view of development of a 10 µM MHC-B MO morphant (F) and a 10 µM control MO embryo (G) with time in minutes shown. Insets in C and G show bottle cells (brackets indicate regions magnified in insets). Scale bars: 500 µm, except 1 mm in D.