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Fig. 3. Myosin IIB MO-mediated failure of gastrulation is dose dependent. (A-D) Still images from simultaneous time-lapse videorecordings showing vegetal views of control (A) and morphant Xenopus embryos injected with 2.5 μM (B), 5 μM (C) and 10 μM (D) MHC-B MO. Embryos are oriented with their dorsal side up. At stage 10 (t=0), bottle cells form in the dorsal lip of the blastopore of all control and morphant embryos. By control stage 12 (t=2.5), ventral bottle cells have formed in all control and morphant embryos, but blastopore closure is delayed in a MHC-B MO dose-dependent manner. The site of blastopore closure in 2.5 μM (B, t=7.5) morphant embryos is not located as ventrally as in control embryos (A, t=7.5). Asterisks indicate the center of the yolk plug at t=0 and the point of blastopore closure at t=7.5. (E-H) RNA in situ hybridizations of stage-13 embryos for brachyury expression reveals the extent of notochordal morphogenesis in a control embryo (E), and reduced notochordal morphogenesis in a 5 μM morphant (F). The 5μ M morphant embryos exhibit some variability in notochordal extension (G), but 10 μM morphant embryos essentially lack notochord extension (H). |
