The APC/C and securin control SEP-1 localization in meiosis I. Prometaphase I embryos within the spermatheca expressing endogenously tagged SEP-1::GFP (green) with chromosome marker H2B::mCherry and cortical granule cargo protein mCherry::CPG-2 (magenta) in control (A–A″), ify-1(RNAi) (B–B″), or apc-2(RNAi) (C–C″). (A) In control embryos, SEP-1::GFP is localized to kinetochore cups and linear elements near the spindle (insets in A, B, and C show SEP-1::GFP on a bivalent in greyscale, white lines indicate the region used to generate a line scan in A′, B,″ and C″). (A′) Line scan showing the SEP-1::GFP and H2B::mCherry fluorescent profiles. (A″) In the cortex, SEP-1::GFP is localized to linear elements (arrow) but not vesicles (arrowhead). (B and B′) Prometaphase I ify-1(RNAi) embryos have reduced SEP-1::GFP signal mislocalized at chromosomes, with some signal at the midbivalent. (B″) SEP-1::GFP precociously localizes to cortical granules (arrowheads) in addition to linear elements (arrow) after securin depletion. (C–C″) In apc-2 (RNAi) prometaphase I embryos, SEP-1::GFP localization is normal on chromosomes and linear elements. Scale bars: 5 µm, except the 1 µm bars for insets found in A, B, and C.