Fig. 3. Recapitulating the Ngn1 expression pattern in the mouse requires two zebrafish ngn1 gene regulatory regions. (A) The 8.4 kb sequence upstream of zebrafish ngn1 drives reporter expression in the mouse telencephalon (arrow). (B,C) Comparison of the expression of the transgene with the expression of the endogenous Ngn1 gene in coronal sections (dorsal up) shows that this fragment recapitulates fully the endogenous telencephalic expression of Ngn1. The sharp ventral boundary of Ngn1 and transgene expression is indicated by a line. (D) Whereas the complete –8.4ngn1:gfp transgene recapitulates the endogenous pattern of Ngn1 (C), reporter activity is lost dorsally (arrow), but remains laterally (arrowhead), in transgenic lines with the LSE deleted [–8.4(del3)ngn1:gfp]. (E) Expression in the lateral telencephalon (arrowhead) is driven by an element within 3.1 kb of the ngn1 regulatory region (–3.1ngn1:nlacZ). (F) Deletion of LATE [–3.1(del LATE)ngn1:nlacZ] abolishes the lateral activity of the –3.1ngn1:nlacZ transgene. Thus, two regulatory regions of the zebrafish transgene control the spatial expression of ngn1 in the mouse pallium. (G) Summary of the activities of LATE and LSE in the dorsal telencephalon of mouse. m, mantle zone; v, ventricular zone. Mouse embryos are at 12.5 dpc. Two transgenic lines were analysed per construct. With the expception of A, which is a lateral view of a whole-mounted mouse embryo, panels show coronal sections through the telencephalon, with dorsal up.