DEV02603 Supplementary Material

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• Supplemental Figure 1 (Adobe PDF) -

  Fig. S1. (A) Sequence of the Paracentrotus lividus cDNA open reading frame. The kinase domain is boxed. The conserved lysine of the active site and the threonine which is part of the TQE motif in the so called autophosphorylation lip of kinase domain VIII are circled. (B) Alignment of the NLK amino acid sequence with the Drosophila, Fugu, human and Xenopus NLK proteins.

• Supplemental Figure 2 -

  Fig. S2. (A) A C-terminally truncated form of the sea urchin Delta possesses a dominant-negative activity. In the case of the Drosophila Notch ligands, it has been shown that removing the intracellular domain of Delta or Serrate causes these ligands to behave as dominant-negative versions that are potent antagonists of Notch signalling (Sun and Artavanis-Tsakonas, 1996). We constructed a similar truncated version of sea urchin Delta ligand by inserting a stop codon immediately after the transmembrane domain. Overexpression of this truncated version of Delta severely delayed the onset of gastrulation but an archenteron eventually formed and the embryos gastrulated (parts a,d). However, although in control embryos numerous mesenchymal cells could be seen budding of the tip of the archenteron during gastrulation, the archenteron of the injected embryos remained smooth and secondary mesenchyme cells did not form (parts b,e). Indeed, these larvae developed into typical pluteus larvae but were completely albino (parts c,f). This result shows that truncated forms of Delta also function as antagonists of Notch signaling in the sea urchin embryo. (B) (a,b) NLK localizes mainly to the nucleus. mRNA encoding a fusion protein between GFP and NLK was injected into the egg and the subcellular localization of NLK was examined at the blastula stage. (g) Fluorescence image of a blastula stage embryo flattened to show all the cells into a single focal plane. (h) High magnification view.