Fig. 1. (A) Alignment of Wnt8/WntD protein sequences. Sequences of Wnt proteins from Drosophila melanogaster (WntD), Branchiostoma floridae (cephalochordate, BfWnt8), Gallus gallus (chicken, CWnt8), and Danio rerio (zebrafish, ZWnt8) are shown. The lightly shaded boxes highlight the conserved amino acid residues. WntD has fewer conserved residues when compared with other members of this subfamily. However, 20/22 of the characteristic cysteine residues are conserved (asterisks). (B) Degree of conservation among WntD and Wnt8 family members. The percent identity/percent similarity is shown in the table. WntD is more distally related to other members in the Wnt8 subfamily. (C-J) Expression pattern of Drosophila wntD in wild-type embryos. In situ hybridization was performed using an antisense probe generated from a wntD cDNA clone. The embryos are oriented with the anterior to the left. For sagittal views, the dorsal side is up (C,D); for other embryos, the ventral views are shown (E-J). The embryo in C is a pre-cellular blastoderm (stage 4), D is a cellular blastoderm (stage 5), E is an early gastrula-stage embryo (stage 6), and F is a gastrula-stage embryo with a ventral furrow, indicated by the arrow (stage 6). The embryos in G-J are at various stages of germ-band extension (stages 7, 8, 9 and 10). During gastrulation, the cephalic furrow (arrowhead in panels E,F) is formed at approximately the same time as the ventral furrow. The expression of wntD appears first in the anterior and posterior regions of the pre-cellular blastoderm (C), and then in the ventral cells and mesectoderm (D-F). Expression continues in the ventral mesectoderm (G), and de novo expression appears in the ventral neuroectoderm (G-J).