Animal injection of Dse-MO caused a decreased number of melanocytes, a reduction of head and eye structures, a lack of dorsal fin tissue and a kinked shortened tail in stage 40 embryos (Fig. 2E). Both the control-MO and Dse-5MM-MO, which contains five base mismatches with the Dse target mRNA, had no effect (Fig. 2D,F). Histological analysis at stage 38 indicated that Dse-morphant tadpoles had a hypoplastic notochord and somite structures that were dorsally abutting above the neural tube (Fig. 2G,H). Moreover, Dse knockdown led to a reduction in the mandibular, hyoid and branchial cartilage in the head at stage 45 (Fig. 2I-K). Interestingly, defects in melanocyte, craniofacial skeleton and dorsal fin formation are characteristic of deficient NC formation (Tucker, 1986; Sadaghiani and Thiébaud, 1987; Tucker and Slack, 2004), which suggests that DS-epi1 is required for NC development. Animal injection of Dse mRNA had no apparent effect on embryonic development at stage 40 and did not affect the formation or migration of Twist+ CNC cells at stages 16 and 26, respectively (Fig. S3).
