Fig. 1. Expression of GLP-1 in pos-1 and spn-4 mutants. Embryos were stained with an anti-GLP-1 antibody. (A-F) Four-cell stage embryos. (G) One-cell stage embryo. Anterior is towards the upper left, posterior is toward the lower right, dorsal is towards the upper right and ventral is towards the lower left. Scale bar: 10 µm. (A) Wild type. GLP-1 was detected only in the ABa and ABp blastomeres, mainly at the membrane. (B) glp-1(RNAi) embryo. In this embryo, there was no expression of GLP-1. Thus, the staining shown here gives the level of the background signals. (C) pos-1(zu148) and (D) pos-1(ne51) embryos. GLP-1 was detected at the membrane in all four blastomeres. (E) spn-4(tm291). GLP-1 was not detectable. (F) pos-1(zu148); spn-4(tm291) double mutant embryo. GLP-1 was detected in all four blastomeres. (G) One-cell stage pos-1(zu148) embryo. GLP-1 is not detectable.