(A) Clustal Omega alignment of the predicted amino acid sequences of LvAlx4 and LvAlx1. (C–I) Embryos fixed at the mid-late gastrula stage and labelled with 6a9 antibody. (C’–I’) DIC/fluorescence composite images of the same embryos. (C, C’) Uninjected control embryo. (D, D’) Positive control embryo co-injected with LvAlx1 MO and LvAlx1.WT.GFP. (E, E’) Embryo co-injected with LvAlx1 MO and LvAlx4 mRNA showing no 6a9-positive cells. (F, F’, G, G’ and H, H’) Chimeric forms of LvAlx4 containing the entire C-terminal region of LvAlx1, Domains 2 and 3, or Domain 2 alone, are able to rescue PMC specification and patterning. (I, I’) Embryo injected with LvAlx1 MO alone (negative control).