At the late neurula stage, Twist and Snail2 demarcate the mandibular, hyoid and branchial segments at the onset of CNC migration (Fig. 5A,D). DS-epi1 knockdown disturbed the segregation of CNC segments and shortened the early cell migration streams (Fig. 5B,C,E,G). In tailbud embryos, Twist and Sox9 label migrated CNC cells around the eye vesicle (mandibular stream), and in the hyoid and branchial arches (Fig. 5H; Fig. S5D). Dse-MO restricted the ventral migration of the CNC cells (Fig. 5I,M; Fig. S5E,I) and decreased the Rax and Sox9 expression in the eye and lens placode, respectively (Fig. S5C,E). The Dse-morphant migration defects were rescued by the co-injection of Dse* mRNA (Fig. 5F,G,J,M; Fig. S5F,I). Moreover, the injection of the human pcDNA3/CTAP-DSE expression plasmid restored normal CNC cell migration in the Dse-morphant embryos (Fig. 5K; Fig. S5G), whereas the catalytically inactive pcDNA3/CTAP-DSE (H205A) construct had no effect (Fig. 5L,M; Fig. S5H,I). Western blot analysis confirmed that pcDNA3/CTAP-DSE and pcDNA3/CTAP-DSE (H205A) (Pacheco et al., 2009a) in injected Xenopus embryos produced equal amounts of protein (Fig. 5N).
