Fig. 6.

The onset of unc-120 expression is not timed by the 4MS, 4C, 1D→8MS, 8C, 2D divisions. (A) Gene expression trajectory of unc-120 in N2 animals at 20°C, noting the round of divisions that leads from 4MS,4C,1D to 8MS,8C,2D with the same symbols used as in Fig. 4A. Lineage data are the same as in Fig. 1. (B) Positions of unc-120 transcripts overlaid on a DAPI nuclear stain maximum projection in embryos with the same number of cells from wild-type and a div-1(g19) strain with slowed divisions. unc-120 expression onset occurs at a much earlier cell stage in the mutant. The mutant expression pattern is approximately correctly localized (see supplementary material Fig. S15). (C) Lineage of a wild-type embryo at 25°C. (D) (Left) Lineage of a representative div-1(or148) embryo. (Right) Gene expression trajectories for unc-120 in a div-1(or148) strain plotted against the assigned embryo age based on the representative lineage on the left. The marked divisions correspond to the same set of divisions as in A. (E) Same as C for the div-1(g19) strain. In both div-1 mutants, unc-120 rises well over 200 transcripts per embryo before the noted divisions, whereas in wild type the unc-120 expression onset occurs during this block of divisions. This suggests that unc-120 expression onset does not require the cell divisions that normally occur concurrently.