Fig. 4

Fig. 4

Effects of transient gbx2 induction on brain formation during development. (A) Schematic structure of heat-inducible gbx2 (hsp70l:gbx2). FT, FLAG tag; pA, polyadenylation signal. (B) Embryos treated with heat shock (HS) were observed at 24 hpf. Half were normal (a, a2), and the remaining embryos showed defects in the isthmus. (b, b2) Embryos showing incomplete isthmic constriction (mild isthmus defect). (c, c′) Embryos completely lacking isthmic constriction (severe isthmus defect). Scale bar, 200 µm. (C) Offspring embryos from a cross between wild-type and hsp70l:gbx2^+/– Tg fish were exposed to HS at the stages specified at the bottom of the graph and scored for the isthmus defects at 24 hpf. (D) Genotyping of embryos exposed to HS at the specified stages. G, genomic sequences amplified for positive control; H, hsp70l:gbx2-derived sequences showing that the embryos harbored the transgene (arrowheads); (M) size marker (500 bp). All normal embryos were negative, and all affected embryos harbored the transgene.