Fig. 3

 (a) zebrafish slit2 in situ hybridization. slit2 is expressed in the telencephalon, in the dorsal hindbrain, the midbrain basal plate and floorplate and the ganglion cell layer in the eye. Two sections, on the level of the hindbrain and of the spinal cord, show that cranial nerve nuclei and motor neurons are negative for slit2 transcripts. (b) Human SLIT2 gene with miRNA218-1 located in intron 14. The HS1 element (1165 bp) is 52 kb upstream including intron 5 and exon 6 sequences. UCSC genome browser indicates sequence conservation in all vertebrate genomes, including the basal vertebrate lamprey. (c) Transgenic larvae with hs1-driven GFP. The expression pattern is that of miR218, but when compared to the enhancers identified within SLIT3 (Fig. 2), the expression in the vagal nerve nucleus is much weaker and expression in anterior cranial nerve nuclei is missing.