GFP::IFY-1 ^DM inhibits chromosome segregation and exocytosis. (A) GFP::IFY-1^WT or (B) GFP::IFY-1^DM (green) with H2B::mCherry (magenta) during meiosis I. Chromosomes move apart quickly in GFP::IFY-1^WT but are severely delayed in GFP::IFY-1^DM embryos. Time (s) is relative to anaphase onset. (C) Average distance between chromosomes during anaphase I is significantly reduced in IFY-1^DM::GFP embryos relative to control (N = 9 for GFP::IFY-1^WT, N > 18 for GFP::IFY-1^DM, asterisks denote a statistically significant difference. P value = <0.05). (D) Frequency and images of chromosome segregation defects (yellow caret) observed in embryos expressing GFP::IFY-1^DM (green, H2B::mCherry in magenta). N = number of embryos scored. (E–K) GFP::IFY-1^DM blocks cortical granule exocytosis. (E) Quantification of cortical granules in a single spindle plane over time after anaphase I onset (N = 6 for GFP::IFY-1^WT, N = 7 for GFP::IFY-1^DM). Asterisks denote a statistically significant difference, P value <0.0001. Error bars represent standard error of the mean. (F–H) Images shown of GFP::IFY-1^WT or (I–K) GFP::IFY-1^DM (green) and mCherry::CPG-2 (magenta, arrowheads) during meiosis I. Time (seconds) is relative to midbivalent localization. In wildtype, most vesicles (arrowheads) undergo exocytosis after 120 s of anaphase onset (G) while mCherry::CPG-2 is extracellular (H, yellow asterisk). (I–K) In contrast, cortical granules (arrowheads) are retained in GFP::IFY-1^DM embryos, even after several minutes. Scalebar: 5 µm (A, B, and D), 10 µm (F–K).