Figure 3.

Sas4 is required for equal cell division and cell cycle progression. (A) Dividing WT and sas4Δ cells (DIC). In WT cells, the division plane is positioned equatorially, whereas sas4Δ cells have anteriorly positioned division furrows. (B) Percent of dividing cells in the total cell population in WT versus sas4Δ cells as a function of time after SAS4 knockout. Experiment was performed in triplicate, and at least 100 cells per cell line and time point were counted per experiment. Error bars denote SEM. (C) Percentage of dividing cells that exhibit the hammerhead phenotype as a function of time post-knockout. By 24 h post-knockout, nearly all dividing sas4Δ cells exhibit the hammerhead morphology. Experiment was performed in triplicate, and at least 100 cells per cell line and time point were counted per experiment. Error bars denote SEM. (D) BBs (green, centrin) and DNA (blue, Hoechst) in dividing WT and sas4Δ cells. Arrows and arrowheads denote macronuclei and micronuclei, respectively. (E) Quantification of the percentage of the total cell population that displayed nuclear gain or loss in WT or sas4Δ cells. Micronucleus, Mic; macronucleus, Mac. Experiment was performed in triplicate with between 24 and 35 cells analyzed per replicate per cell line. Error bars denote SEM. (F) Quantification of the number of micronuclei (Mic) and macronuclei (Mac) in dividing hammerhead sas4Δ cells in the anterior and posterior cell halves. 23 cells were analyzed. Error bars denote SEM. Scale bars, 5 µm.