First detected at centrosomes after pronuclear meeting in post-meiotic 1-cell embryos. PLK-1 remains associated with centrosomes as the embryo enters prophase of mitosis and this localization persists through late anaphase. PLK-1 also detected in chromosome-specific localization of PLK-1 diminishes during anaphase and is not observed during telophase. PLK-1 detected at the region of spindle overlap during telophase (coincident with alpha-tubulin staining). At the time this appears as two discrete points suggesting it was part of a ring-like structure. PLK-1 is detected in newly fertilized embryos. PLK-1 staining in mature, unfertilized oocytes is diffuse and cytoplasmic. In new fertilized embryos, PLK-1 staining is coincident with six maternal bivalent pre-metaphase chromosome before their segregation. As fertilized embryos progressed through anaphase of meiosis, PLK-1 was again coincident with the dividing chromatin but has also redistributed and was found in the areas between the dividing chromatin.
Asymmetric expression of imb-2 in AWCON was also observed in our initial assessment of the imb-2 expression pattern using imb-2 fosmid::GFP in which we fused GFP with the C terminus of IMB-2 by homologous recombination, that rescued imb-2(vy10) mutants.
NOS-2 protein is expressed sequentially during embryogenesis. First detected expression of NOS-2 in the 1-cell stage; at this stage, NOS-2 was present uniformly throughout the embryo. No NOS-2 expression was detected in 2- to 20-cell embryos. NOS-2 expression reappeared in the 28-cell stage in the cytoplasm of the germline blastomere P4. In some embryos, NOS-2 staining appeared to be concentrated in a few perinuclear foci. NOS-2 expression continued in P4 and its two daughters Z2 and Z3 until approximately the 200-cell stage. NOS-2 levels decreased sharply in later stages and were undetectable by the 550-cell stage.