In wild type, whereas
glp-1 mRNA is uniformly distributed in both oocytes and early embryos (1 to 4 cells), GLP-1 protein is first seen at the 2-cell stage, in the anterior AB but not the posterior P1 blastomere; GLP-1 continues to be expressed in AB descendants through the 28-cell stage. For
par-4, 90% (27/30) had similar levels of GLP-1 in all blastomeres, while three 4-cell embryos had noticeably lower levels of GLP-1 in two blastomeres. P granules stained weakly and were present in all blastomeres (n = 4). Adult germ lines (n = 20), oocytes (n = 12), and 1-cell embryos (n = 5) had a normal GLP-1 pattern. Thus,
par-4 is required for spatial but not temporal regulation of GLP-1 asymmetry. The time of onset of GLP-1 translation appears to be normal in mutant embryos, and the presence of GLP-1 in P1 descendants is likely to reflect ectopic translation there.