Fig. 8. aPKC accumulation at the CAB is dependent on actin microfilaments and independent of microtubules. Embryos were incubated with the indicated inhibitor then fixed, immunolabelled and examined by confocal microscopy. (A-D) Treatment at 2-cell stage for 90 minutes, the time equivalent to three cell cycles. Images on the right show aPKC label (surface views); images on the left show Hoechst label in the same embryos (central planes containing chromatin). In embryos treated with cytochalasin or latrunculin, nuclear cycles continue and each blastomere accumulates 8-16 patches of DNA, which are symmetrically arranged and either decondensed as interphase nuclei (A) or condensed in mitotic configurations (B). In embryos treated with nocodazole (C,D) nuclear cycles arrest; DNA is condensed and dispersed randomly along the cleavage furrow. In C (lateral view of one embryo) and D (posterior view of another embryo), arrowheads indicate CAB-like accumulations of aPKC protein. (E-G) Treatment at 16-cell stage for 30 minutes, the time equivalent to one cell cycle. Images show aPKC labelling in posterior blastomeres (B5.2 cells, surface views) from a typical treated embryo. Arrowhead in G indicates a pair of CABs. Graphs show the percentage of embryos in which a concentrated cortical patch of aPKC protein was either present, absent, or weakly apparent in B5.2 cells; at least 20 embryos were scored for each treatment.