Hurp^−/− oocytes present late anaphases and lagging chromosomes and spread MII plates. (A) HURP levels are constant during meiotic maturation. Oocytes were collected in prophase I (ProI), 4 h after NEBD (MI), during polar body (PB) extrusion, and during MII. (B) HURP is absent in liver extracts from Hurp^−/− mice. (C) Percentage of first polar body extrusion over time in wt versus Hurp^−/− oocytes. (D) Aberrant bivalent separation in Hurp^−/− oocytes. (top) wt with normal chromosome separation. (bottom) Hurp^−/− with lagging chromosomes (arrow) and delayed anaphase I, both expressing H2B-RFP. Asterisks, polar bodies. All times are given in hours and minutes after NEBD. (E) Hurp^−/− oocytes present disorganized MII plates, which were rescued by HURP expression. Chromosomes in MII from wt (top left), Hurp^−/− (top right), and Hurp^−/− oocytes expressing GFP-HURP (bottom). (F) HURP localizes in the vicinity of chromosomes in the spindle midzone. Oocytes stained with Hoechst (blue), tubulin (green), and HURP. Asterisk, polar body. (G) GFP-HURP behaves like endogenous protein. Oocytes are shown expressing EB3-mCherry (green) and GFP-HURP. Maximal Z projections are shown. Asterisk, polar body. (H) HURP does not label K fibers in prometaphase I. Oocytes were stained at NEBD + 5 h (prometaphase I), NEBD + 8 h (MI), and MII with Hoechst; CREST for kinetochores; and HURP. Maximum projections or selected stacks are shown. Asterisks, kinetochore MTs not decorated by HURP. Arrows, HURP on interpolar MTs. Bars, 10 µm.