Fig. 3

ALK3 and ALK6 are required for dorso-ventral patterning. a 2-cell-stage embryos were injected with 1.6 pmol control MO, ALK3 MO or ALK6 MO in both blastomeres as indicated, cultured till stage 10.5 and bisected into dorsal (d) and ventral (v) halves. Expression of the organizer genes chordin (chd), admp and goosecoid (gsc) and the ventral genes bmp4, vent1 and sizzled was analyzed by RT-PCR. The images show one set out of three independent experiments. (b-g) Embryos were injected with Fluorescein-labeled dextran as lineage tracer and antisense Morpholino oligonucleotides as indicated into one blastomere at the 2-cell-stage. For rescue experiments, 50 pg of alk3 RNA or alk6 RNA were co-injected. The embryos were cultured till stage 10.5 and chordin expression was visualized by whole-mount in situ hybridization. b Representative examples of phenotypes injected as indicated are shown. Asterisks indicate the injected side, dashed lines mark the dorsal midline as determined by the lineage tracer. c The chordin-positive area and staining intensity have been measured on the injected and uninjected side of each embryo. The graph displays the average ratio of area size between injected and uninjected side (+SEM) as well as the mean intensity/area (+SEM) from three independent experiments. Differences of area ratios between injection groups have been analyzed using a separate variance t-test and statistically significant deviations are indicated by double asterisks (p-value < 0.01); n.s.: not significant. The average intensity/area did not change significantly. d For comparison, an embryo injected with 50 pg RNA encoding dnALK3 is shown. In 10 out of 38 embryos dnALK3 induced strongly expanded or ectopic chordin expression