Fig. 6. Ci-Delta2 encodes a Delta-like molecule. (A) Alignment of the putative DSL domain of Ci-Delta2 with DSLs from other Delta proteins. Ci, Ciona intestinalis; lv, Lytechinus variegatus (green sea urchin); Z, zebrafish (Danio rerio); C, chick; Dm, Drosophila melanogaster; spider, Cupiennius salei. The DSL domain of Ci-Delta2 was identified using the SMART programme, but gave a score less significant than the required threshold to be confidently predicted as a DSL domain using this programme (Letunic et al., 2004; Schultz et al., 1998). (B) Ci-Hes-b expression at the early gastrula stage is a target of Ci-Delta2. Expression of Ci-Hes-b is shown following the treatment indicated above the panels. Ectopic expression was sometimes observed in the mesenchyme lineages following injection of dnDel2 (far right). The graph shows the percentage of embryos (y-axis) showing expression in at least one cell of the A-line (A8.16, A8.8, in grey) and B-line (B8.6, in blue) following the treatments indicated on the x-axis. n=total number of embryos examined. The schematic drawing shows the positions of these blastomeres. Dots indicate the blastomere derivatives that were expressing Ci-Delta2 at the 64-cell stage. At the early gastrula stage, Ci-Delta expression is downregulated in A7.6, while that in A8.15/A8.16 (daughters of A7.8) becomes stronger (Hudson and Yasuo, 2005).