Figure 8. Src^SRC-1 mediated signaling from P2 provides the cell-extrinsic regulation of cytokinesis in EMS.

(A) Schematic showing EMS and P2 cell-cell signaling during EMS cell fate specification. (B) Schematic showing how the EMS spindle angle was calculated. (C) Graph showing the EMS spindle angle (as a read-out for proper EMS cell fate specification) for different EMS (left) and P2 (right) cells within paired-blastomere doublets from control or formin^cyk-1(ts) embryos that successfully complete or fail in cytokinesis. Note: the doublets analyzed here are the same as those used in Figure 7. (D) Graph showing the frequency of successful cytokinesis for each cell type in intact formin^cyk-1(ts); control(RNAi) and formin^cyk-1(ts); Src^src-1(RNAi) embryos. Error bars, mean ± SD. Two tailed Mann-Whitney test (Supplementary file 1); n.s., no significance, p>0.05; *p≤0.05; **p≤0.01; ****p≤0.0001. (F) Model showing the role extrinsic and intrinsic factors in EMS and P2 cytokinesis. Temperature, 26°C; scale bar = 10 µm.

Figure 8—figure supplement 1. Disrupting Src^SRC-1 does not cause cytokinesis failure in control embryos.

(A) Graph showing the frequency of successful cytokinesis for each cell type in intact control embryos after control(RNAi) or Src^src-1(RNAi). Temperature, 26°C. See also Supplementary file 1.

Figure 8—figure supplement 2. Disrupting cellular polarity causes division failure in all cell types.

(A) Graph showing the frequency of successful cytokinesis for each cell type in intact formin^cyk-1(ts), control(RNAi) and formin^cyk-1(ts), par-6(RNAi) embryos. PAR-6 is a protein essential for anterior posterior cell polarity in the one-cell C. elegans embryo (Watts et al., 1996). Temperature, 26°C. See also Supplementary file 1.