Overexpression of a membrane-targeted intracellular domain of Celsr (Lyn-Celsr) causes a convergence extension defect during zebrafish gastrulation. (A-H) Wild-type (WT) embryos (A-D) or wild-type embryos injected with 100 pg RNA encoding Lyn-Celsr (E-H). (A,E) Lateral views of pharyngula stage living WT (A) and Lyn-Fmi-expressing (E) embryos. The Lyn-Fmi-expressing embryo shows a shorter body axis in this case associated with cyclopia. Dorsal views (B,C,F,G) of tail-bud stage wild-type embryos (B,C) and Lyn-Celsr-expressing embryos (F,G). Lateral views of 80% epiboly WT (D) and Lyn-Celsr-expressing (H) embryos. Anterior is upwards and genes analysed are indicated in the bottom right-hand corner. (I-R) Analysis of axial and lateral mesendermal cells using a photo-conversion strategy. Labelled axial mesendermal cells at shield stage (6 hpf) in control (I) and Lyn-Celsr embryos (K) were analysed at tailbud stage (10 hpf) (J,L, respectively). Labelled lateral mesendermal cells at shield stage (6 hpf) in control (M) and Lyn-Celsr embryos (O) were analysed at tailbud stage (10 hpf) (N,P, respectively). Lateral views (I-P). Quantification of anterior migration of axial cells (Q) and dorsal migration of lateral cells (R). Blue, Lyn-Celsr-expressing embryos; red, WT embryos. Means and s.d. are shown. Asterisks indicate statistically significant differences (P<0.05; Student's t-test). Note that Lyn-Celsr-expressing embryos show both convergence and extension defects.
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