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Figure S3.
Maternal xNorrin is required for anterior neural formation. (A) The genomic sequence of the first exon and the first intron boundary of xNorrin. The first two presumptive nucleotides "gt" of the intron are labeled in red. The splicing site sequence targeted by xNor-spMO is indicated by a green line. See Materials and Methods for sequence information for all MOs. (B) RT-PCR to detect xNorrin mRNA expression in stage 15 embryos. xNor-spMO (20 ng) inhibited zygotic xNorrin transcription, while xNor-MO (20 ng) or xNor-misMO (20 ng) (a four-nucleotide mismatched MO compared to xNor-MO) did not. (C-F) Representative MO-injected tadpole at stage 34. xNo-spMO (20 ng) did not cause severe anterior defects, unlike xNor-MO. (G) Summary of (C-F). Uninjected: n = 30; MO: n = 24; misMO: n = 30; spMO: n = 40. (H) xNor-MO injection inhibited anterior neural formation. Whole-mount in situ hybridization was performed for XBF-1 mRNA (anterior neural marker) and HoxB9 mRNA (posterior neural marker) in stage 15 embryos. Dorsal animal cell injection of xNor-MO (10 ng) at the four- to eight-cell stage greatly reduced the expression of the anterior neural marker XBF-1 (63%, n = 32), while injection of xNor-misMO (10 ng) or xNor-spMO (10 ng) (27%, n = 29) was far less effective to reduce the expression. Neither xNor-MO (n = 25) nor xNor-spMO (n = 25) injection affected HoxB9 expression. MOs were co-injected with β-gal mRNA (100 pg). β-gal staining is shown in red. XBF-1 staining embryos are shown in anterior view, and HoxB9 staining embryos are shown in dorsal view, with the anterior pole at the top. misMO, xNor-misMO; MO, xNor-MO; spMO, xNor-spMO. |