Fig. 1. The –8.4ngn1:gfp zebrafish transgene recapitulates the pattern of endogenous ngn1 transcripts and drives telencephalic expression in the zebrafish embryo. (A) The 8.4 kb upstream zebrafish ngn1 regulatory sequence drives GFP expression in the telencephalon (arrow) and in the diencephalon. (B,C) Comparison of the endogenous ngn1 gene (B) and the gfp transgene (C) by in situ hybridisation indicates that the gfp transgene is capable of recapitulating the endogenous telencephalic (t, indicated by arrows) and diencephalic expression of ngn1. Expression is detected in at least six regions of the diencephalon, comprising the epiphysis (e), pretectum (pre), dorsal thalamus (dt), ventral thalamus (vt), preoptic area (po) and posterior tuberculum (pt). Transcripts are also localised in the midbrain tegmentum (tg). Zebrafish embryos are at stage 28 hpf. Panels show lateral views of whole-mounted embryos oriented anterior to the left and dorsal up.