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Figure 2. FGF signaling effects on endoderm and mesoderm. These embryos have been processed by in situ hybridization for expression of the indicated transcript above each column. Embryos were treated with DMSO or SU5402 from the 8- to 16-cell stage as indicated on the side. A,B: Lateral views; embryos were collected at the blastula stage, 7.5 hr post-fertilization. C-S: Gastrula stage. C-N: Blastoporal views. O,P: Lateral views with vegetal to the bottom. Q-S: Embryos were injected into one cell at the two-cell stage with the dominant-negative FGFR1 construct XFD (500 pg); the red staining is the lineage tracer n beta gal. T: Whole embryos were treated with either DMSO or SU5402, collected at the time indicated above the lanes, and analyzed by RT-PCR for expression of the indicated markers along the side. ODC was used as a loading control. |
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Figure 5. VegT activity in the absence of FGF signaling. VegT has dose-specific effects in the whole embryo. A,B: Control uninjected embryos at the mid-gastrula stage and processed by in situ hybridization for expression of sox17 or xbra. C-L: Embryos were injected with different doses of VegT mRNA into one cell at the two-cell stage marked by the lineage tracer nuclear beta -gal in red and analyzed at the mid-gastrula stage. All embryos are displayed in lateral views with the blastopore toward the bottom. At a very low dose, VegT mRNA has no detectable effect (C,D). At the 10-pg dose, VegT induces ectopic xbra expression but not sox17 while higher doses induce ectopic sox17 at the focal point of injection and xbra at the periphery (E-L). M-X: FGF signaling is necessary for VegT-mediated expansion of xbra but not sox17. Embryos were either uninjected, or injected with VegT mRNA (250 pg) or FGF8b mRNA (10 pg) and treated with either DMSO or SU5402 as indicated. At the early gastrula stage, embryos were analyzed for xbra and sox17 expression. Y: An RTPCR experiment on whole embryos treated as indicated along the top and analyzed for a range of markers. EF1 alpha and ODC were used as loading controls. |
