Fig. 2

Fig. 2 Spatio-temporal expression of sqtGFP transgenes reflects endogenous sqt expression. (A) Diagram of three constructs used to make stable transgenic lines with the Tol2 transposase. Each line consists of the GFP reporter gene and 1.4 kb of DNA from the sqt genomic region upstream of the transcription start site. Tg-SqtapGFPi contains 600 bp of the sqt first intron inserted downstream of the GFP poly-adenylation signal. Tg-SqtapGFP lacks the entire first intron. Tg-SqtapGFPiΔNRE is identical to Tg-SqtapGFPi, except that it lacks the 68 bp NRE sequence, shown below. The FoxH1 consensus sites are highlighted in red; Smad consensus binding sites are in black bold. Time-course of gfp expression in Tg-SqtapGFPi (B–E), Tg-SqtapGFP (F–I) and Tg-SqtapGFPiΔNRE (J–M). In all lines, gfp mRNA is induced in dorsal blastomeres soon after MBT (B, F, J). At 5 hpf, gfp is expressed in a ring around the entire margin in all lines (C, G, K). The ring of expression in Tg-SqtapGFP (G) and Tg-SqtapGFPiΔNRE (K) is thinner than the ring in Tg-SqtapGFPi. At 6 hpf, gfp expression in Tg-SqtapGFPi (D) and Tg-SqtapGFPiΔNRE (L) is absent from the margin, but expression persists in Tg-SqtapGFP (arrows) (H). At 8hpf, gfp is expressed in the dorsal forerunner cells in all three lines (red arrowheads) (E, I, M). In Tg-SqtapGFP, expression persists in marginal EVL cells throughout gastrulation (arrows) (I). In all three lines, ectopic gfp expression is detected at the midline (black arrowheads) (E, I, M). (N) The FoxH1 consensus binding sites in the sqt intron are conserved in Tetraodon nigroviridis (Tn), Takifugu rubripes (Tr), Xenopus laevis (Xl), and Mus musculus (Mm).