Gα is required at the membrane to direct spindle positioning in C. elegans embryos. (A and B) Wild-type (A) or goa-1(n1134) (B) one-cell stage embryos stained with antibodies against GOA-1 and α-tubulin. Higher magnifications of cortical regions (red boxes) and accompanying line scans of representative embryos are given as in Fig. 3 and highlight the presence (A) or absence (B) of GOA-1. 10 cells were scored for each condition. (C and D) Wild-type (C) or goa-1(n1134) gpa-16(RNAi) (D) two-cell stage embryos stained with antibodies against DHC-1 and α-tubulin. Higher magnifications of cortical regions (red boxes) and accompanying line scans of representative embryos are given as in Fig. 3 and highlight the presence (C) or absence (D) of DHC-1. 10 cells were scored for each condition. (E–G) Images from time-lapse DIC microscopy of C. elegans embryos from metaphase in the one-cell stage (left) through anaphase in the one-cell stage (middle) and in the early two-cell stage (right) from the wild-type (E), goa-1(n1134) gpa-16(RNAi) (F), and goa-1(sa734) gpa-16(RNAi) (G; see also corresponding Video 6). Symbols and tracking as described in the legend of Fig. 3. Red discs and white triangles indicate the position of centrosomes during metaphase and the cleavage furrow, respectively. Note equal size of blastomeres in goa-1(n1134) gpa-16(RNAi) (F) and goa-1(sa734) gpa-16(RNAi) (G) embryos. Time is given in minutes and seconds. au, arbitrary unit; α-TUB, α-tubulin.