Fig. 4

Overexpression of Brg1 mRNA leads to reduced forebrain size and rescues the Brg1-MO knockdown phenotype. A-D: Embryos were injected with 500 pg of full-length Brg1 mRNA at the one- to two-cell stage. Embryos were allowed to recover and, at indicated times, were fixed and used for in situ hybridization using six3- or pax6-specific probes. Arrowheads indicate the areas of affected gene expression. E,F: Control-injected or 500 pg Brg1 mRNA-injected embryos at 48 hpf. Note unequal eye/lens and fused eye/lens in Brg1 mRNA-injected zebrafish embryos (F). The phenotypes of the Brg1 mRNA-injected embryos were approximately 30% each in the two panels in F (n = 200). G-I: Five hundred embryos at the one- to two-cell stage were control-MO-injected (10 ng/embryo) or injected with Brg1-MO (10 ng/embryo), or embryos were injected with Brg1-MO (10 ng/embryo) plus 500 pg of full-length Brg1 mRNA. At 24 hpf, embryos were analyzed, quantitated, and photographed. Arrowheads indicate the head of the embryos. Note small head and body size with signs of apoptosis in H (Brg1-MO treated). With the concentration of the Brg1 mRNA that was used, more than 90% of the embryos could be rescued. Original magnification 30×.