Fig. 6

Over-expression of sema3Gb in wild-type embryos results in aberrant cranial NCC migration. Manipulation in each panel is under the wild-type genetic background. krox20 and dlx2 are in blue in all panels. Arrows indicate the second cranial NC stream, while arrowheads indicate cranial NCCs in normally cranial NC-free zones. (A) An uninjection control of a wild-type embryo. (B) A mild cranial NCC migration defect (arrowhead), in which a few cranial NCCs were detected in the normally cranial NC-free zone, was occasionally observed in sema3Gb over-expressing embryos. (C) Over-expression of sema3Gb combined with knockdown of endogenous Sema3Fa, Sema3Ga, and Sema3Gb causes a similar mild defect. (D) Knockdown of Sema3D in the presence of over-expression of sema3Gb had a mild defect. (E-F) Over-expression of sema3Gb in wild-type embryos injected with Sema3D, Sema3Fa, Sema3Ga, and Sema3Gb MOs caused a cranial NCC migration phenotype resembling that of lzr/pbx4 mutants. One (arrowhead in F) or both (arrowheads in E) sides of the manipulated embryos showed the cranial NC fusion phenotype. (G) Knockdown of endogenous Sema3D, Sema3Fa, Sema3Ga, and Sema3Gb also had a similar mild defect. (H) Knockdown of Nrp2b suppresses the cranial NC fusion phenotype observed in the manipulated embryos of E and F. An aberrantly migratory cranial NCC is indicated by arrowhead. Scale bar: 40 μm in A–H.