Figure 6.—

slk19 separation-of-function mutants display disrupted anaphase spindle elongation independent of FEAR defects. (A) Example of WT elongation: an otherwise wild-type strain expressing GFP–TUB1 (dKH160-1.2a) was arrested in α-factor, trapped in a microfluidic plate from CellASIC, and imaged every 30 sec while flowing complete medium through the chamber. Yellow dots in the left column were added to mark the location of SPBs. Bar, 5 μm. (B) A cartoon representing a WT trace, highlighting the four observed stages; M, metaphase; F, fast phase; P, paused state; S, slow phase. (C) Individual elongation traces were aligned at anaphase initiation (time = 0 min) and the average distance determined at each timepoint. (D) Comparison of time spent in anaphase and final length of the spindle. Anaphase was deemed completed at the timepoint prior to the rapid movement of SPBs that occurs when the spindle breaks and disassembly begins. (E) The rate of elongation during three 4-minute windows, corresponding to early, mid, or late anaphase, were determined from individual elongation traces and then averaged. Strains and number of cells counted: SLK19 (dKH257-1.2d), n = 25; slk19Δ (dKH256-5.5a), n = 40; spo12Δ (dKH282-5.10c), n = 40; slk19–ΔA (dKH283-1.2b), n = 40; and slk19–ΔG (dKH255-7.6a), n = 100. [D and E, bars show standard deviation (SD) **P < 0.01 and ***P < 0.001 when compared to SLK19 using a two-tailed unpaired t-test.] (F) Anaphase elongation rates of slk19 spo12Δ double mutants. Strains: SLK19 (dKH295-1.9b), n = 32; slk19Δ (dKH296-1.1a), n = 43; slk19–ΔA (dKH297-1.19c), n = 36; and slk19–ΔG (dKH299-1.16d), n = 40.