ZYG-9 and TAC-1 are required for meiosis I anaphase spindle rotation and polar body extrusion.

(A-D) Time-lapse maximum intensity projection images of live control and TS mutant oocytes expressing GFP::ASPM-1 and mCherry::H2B upshifted at meiosis I metaphase; polar body extrusion failed in all three mutant oocytes. Oocytes were rotated so that the cortex was positioned to the left of the spindle; dashed lines depict the oocyte cortex. (E) Early anaphase time-lapse images of live control and TS mutant oocytes after metaphase upshifts. Bar graph quantifies spindle rotation based on the number of chromosomes adjacent to the cortex at the start of chromosome separation in metaphase upshifted oocytes (see Materials and Methods). (F) Spindle angles relative to the cortex at early anaphase in metaphase upshifted oocytes. (G) Number of control and TS mutant metaphase upshifted oocytes that extrude a polar body during meiosis I (see Materials and Methods). Scale bars = 5 μm.