Figure 10. SB431542 treatment during Mnemiopsis development.

Effects of TGF-β inhibitor, SB431542, at 12 hours post fertilization. (A,B, D–F) are treated embryos, while (C, G–I) are controls. (A–C) Confocal projections of embryos stained with anti-tyrosinated tubulin (red) showing the cilia, Alexa-488 phalloidin (green) showing cell borders, and Hoechst 33342 (blue) showing the nuclei. All are aboral views, with the apical organ (ao) in the center. The white arrowheads point to individual comb plates, while the arrows in (C) show the eight comb rowsC. (D–I) are live embryos imaged under DIC. (D) Lateral view of SB431542-treated embryo, showing that pharynx has not invaginated (compare to (G)), and the tentacle bulbs (tb) have formed but are smaller in size. The apical organ appears normal. (E) Aboral view of the same embryo, mid-focal plane, again showing the smaller tentacle bulbs. The ectoderm (ecto) and endoderm (endo) both appear normal. (F) Aboral and surface view, showing the disorganized comb plates (arrowhead), compared to the eight comb rows (arrows) in the control (I).