Fig. 8. Establishment of AP polarity occurs independently of astral microtubules. zyg-11(mn40) (A) or zyg-11(mn40) tba-2(RNAi) (B) meiosis II embryos, wild-type (E,G,I,K) or tba-2(RNAi) embryos (F,H,J,L) during the first mitotic cell cycle, and tba-2(RNAi) embryos during the second mitotic cell cycle (D) are shown. All embryos are stained with antibodies against -tubulin (green in merged image) and a centriolar or polarity marker as indicated (SAS-4, PAR-1, GFP-PAR-2, GFP-PAR-6, PGL-1; red in merged image); DNA is shown in blue in the merged image. A dozen 1 µm confocal optical sections were imaged. The top panels show a projection of all slices for the -tubulin channel. Insets show magnified views of centrosomes; width of inset represents 5 µm. The merged images show a single section for -tubulin and the centriolar or polarity marker, along with a projection of all slices for the DNA signal. Scale bar: 10 µm. (C) Plots of position along the circumference in zyg-11(mn40) tba-2(RNAi) embryos (x-axis, degrees, with 0 degrees being posterior-most) as a function of the distance separating oocyte chromosomes from the cortex (y-axis, µm). Red dots indicate cortical locations where GFP-PAR-2 levels are at least five times higher than in the cytoplasm (determined with Metamorph software). Top plot, ten embryos; bottom plot, embryo shown in B. Note that GFP-PAR-2 is present in the cortical region closest to oocyte chromosomes. (E-L) Pairs of wild-type and tba-2(RNAi) embryos, from approximately the same stage, during prophase of the first cell cycle. In all tba-2(RNAi) embryos lacking detectable astral microtubules, including those with only two tiny dots of -tubulin presumably corresponding to paternally contributed centrioles (F,L, see also D), polarity markers were distributed as in wild type [number of embryos examined for each polarity marker (the number of embryos that only have two tiny dots is given in parentheses): PAR-1, 10 (5); GFP-PAR-2, 6 (1); GFP-PAR-6, 6 (0); PGL-1, 10 (5)].