Differential gene expression along the animal-vegetal axis in the ascidian embryo is maintained by a dual functional protein Foxd
(A) Analysis of the upstream regulatory region of Dmrt1. Illustrations on the left depict the constructs. Blue boxes indicate the LacZ gene and SV40 polyadenylation signal. The numbers indicate the relative nucleotide positions from the transcription start site. Mutated Foxd-binding sites are indicated by the letter X. Graphs show the percentage of embryos expressing the reporter in vegetal cells and a6.5 blastomeres. Note that not all cells or embryos could express the reporter because of mosaic incorporation of the electroporated plasmid. (B, C) LacZ mRNA expression in embryos electroporated with the constructs containing the 486-bp long upstream region of Dmrt1 with an intact (B) or mutant (C) Fox binding site. Black arrows indicate normal expression in a6.5, while magenta arrows indicate ectopic expression in Foxd morphant embryos. Scale bar, 100 μm.