Fig. 1

Meis1b and meis2b are expressed in midbrain and hindbrain and do not influence NC migration. (A) Top: Scheme of deletions in DNA generated by CRISPR/Cas9 in zebrafish meis genes. Red lines mark targeted exons. Meis1a mutants had 37-bp long deletion in exon 8/intron8, meis1b 50-bp in exon 8, meis2a 50-bp in exon2, meis2b 49-bp in exon 8. Bottom: Sequencing of RNA of mutated genes and protein translation sequences in mutated regions. Red arrows point at sites of shifted reading frames. (B) qRT-PCR analysis showing relative expression of meis transcripts in respective mutant line embryos at 24 hpf. Ct values were normalized to gapdh reference housekeeping gene. Relative fold change to calibrator wild-type controls (set to 1, dashed line). (C) Expression of NC marker sox9 relative to meis1b and meis2b in wild type embryos at stage 12 hpf. Dorsal views (top) and lateral views (bottom). Anterior to the left. (D) Migratory streams of NC at 24 hpf labeled by Sox9 (red) antibody, the first stream (mandibular) at the left, the second (hyoid) and the third stream. Dorsal views (top) and lateral views (bottom) with anterior to left. ot, otic, wt, wild type. Scale bar = 100 μm.