Figure 2

Embryonic polarity defects after weak RNAi of B0511.9. (A) wild-type 2 cell embryo after asymmetric first division; anterior AB cell is larger than the posterior P1 cell. (B) B0511.9(RNAi) embryo showing a symmetric first division. (C) PAR-3 at the anterior cortex of a wild-type one-celled embryo at anaphase. (D) PAR-3 on the entire cortex of a B0511.9(RNAi) embryo at anaphase. (E) PAR-2 at the posterior cortex of the wild-type one-celled embryo in (C). (F) PAR-2 in cytoplasmic structures in the B0511.9(RNAi) embryo shown in (D). The PAR-2 antibody shows weak cross-reaction with microtubules. PAR-2 and PAR-3 distributions were scored in wild-type and B0511.9(RNAi) embryos from prophase to the two cell stage. We distinguished weak versus strong classes of PAR staining defects in B0511.9(RNAi) embryos: (1) weak: an enlarged domain of cortical PAR-3 with a reduced domain of cortical PAR-2. (2) strong: complete cortical PAR-3 with PAR-2 in cytoplasmic puncta. In embryos where both meiotic divisions occurred, scored by the presence of two polar bodies, 50% were in the weak class and 17% in the strong class (n = 18). In embryos with a meiotic division defect, scored by the presence of only one polar body, 23% were in the weak class and 63% were in the strong class (n = 49). The PAR distribution defects in B0511.9(RNAi) embryos having two polar bodies suggests that its polarity function is separable from its meiotic function.