| |
Fig. 6. The Xvent2 and XId3 BREs direct expression of a GFP reporter gene to regions of BMP activity in transgenic frogs. Expression of XBMP4 compared to XId3 expression in gastrula, neurula, and tailbud stage embryos is shown in panels (A) and (DF), respectively. Unless otherwise indicated, for gastrula stages, dorsal is to the left and the animal pole up. For neurula stages, anterior is to the left and dorsal is up. For tailbud stages, lateral views are shown. (A, D) At the gastrula stage (10.5), both genes are expressed in the animal cap and excluded from part of the area above the dorsal blastopore lip (arrowheads). (B, E) At the neurula stage (14 5), both XId3 and XBMP4 are expressed in the future cement gland (arrowhead) and the ventral region. (C, F) At tailbud stages (2728), both genes are expressed in the proctodeum (p), the ventral branchial arch/heart region (vbr), the eyes (e), and the otic vesicle (ov). (G) Expression of the 8xXvent2-BRE/GFP-reporter gene analyzed in transgenic embryos. (G) Gastrula stage embryo (stage 10.511); arrowhead, dorsal blastopore lip. GFP mRNA is expressed on the ventral side only, including the ventral marginal zone and the ventral ectoderm. (H) Stage 32 embryo; stained with antisense GFP mRNA. (I) Stage 32 embryo, showing GFP protein fluorescence of the eye (e), ventral branchial arch/heart region (vbr), otic vesicle (ov), somites (s) and proctodeum (p). (J ) Expression of the 7xId3 BRE/GFP reporter gene in transgenic embryos; (J, M, Q) fluorescence of GFP protein; (K, L, N, O, P) expression of GFP mRNA. (J) Stage 11 embryo, vegetal view, dorsal is up. GFP protein is expressed ventrally and laterally but not dorsally. Note that there is also fluorescence in the yolk plug. (K) Stage 10.5 embryo; arrowhead, dorsal blastopore lip. GFP mRNA expression is excluded from the dorsal side. (L) Stage 10.5 embryo, uncleared, vegetal view, dorsal is up; white arrowheads show the limits of the ventral expression; red line, dorsal blastopore lip. Expression is observed only on the ventral side and in the yolk plug. (M) Neurula stage embryo (stage 14), dorsal view, anterior is to the left. GFP protein fluorescence is excluded from the neural plate. (N) Same embryo as in panel (M), dorsal view, anterior is to the left. GFP mRNA expression is excluded from the neural plate. GFP mRNA appears to be expressed in a slightly smaller domain than that of the GFP protein shown in panel (M) likely to due the fact that some of the mRNA disappears by this stage. (O) Same embryo as in panels (M, N), lateral view. GFP mRNA expression is observed only ventrally and is excluded from the neural plate. (P) Stage 32 embryo, stained with antisense GFP mRNA. (Q) Same embryo as in panel (P), but showing GFP protein expression. |
