Fig. 5. PAR-1 and MEX-5/6 function in a feedback loop to regulate expansion of the posterior domain. (A-F) par-1(RNAi) zygote expressing GFP:PAR-2 (Movie 22). (A) Pronuclear formation. (B) Pronuclear migration. (C) Pronuclear meeting. (D-E) Mitosis. (F) Two-cell stage. The GFP:PAR-2 domain is expanded at pseudocleavage compared to wild type (see Fig. 1). (G-L) mex-5(RNAi)mex-6(RNAi) zygote expressing GFP:PAR-2 (Movie 28). Stages same as in A-F. GFP:PAR-2 domain expansion is slowed down compared to wild type (see Fig. 1). (M) GFP:PAR-2 in par-1(RNAi) pie-1(RNAi) (Movie 27). Expansion of the PAR-2 domain is not suppressed (compare with B). (N) GFP:PAR-2 in par-1(RNAi) mex-5(RNAi)mex-6(RNAi) (Movie 26). Expansion of the PAR-2 domain is suppressed. Identical results were obtained in par-1(it51) mex-5(RNAi)mex-6(RNAi) embryos stained for PAR-2 (not shown). (O,P) Wild-type (O) and mex-5(zu199)mex-6(pk440) (P) zygotes stained with PAR-1 antibody. Arrows point to the ends of the PAR-1 domain in the wild-type embryo. PAR-1 is not visible on the cortex of this mex-5(zu199)mex-6(pk440) zygote. (Q,R) Wild-type (Q) and mex-5(zu199)mex-6(pk440) (R) zygotes stained with PAR-3 antibody. PAR-3 extends further posterior.