Actin ring plays a role in guiding PS formation. (A) Actin ring assembly in iqg1-CHDΔ mutant. Cells of strains RNY2594 (iqg1Δ MYO1-GFP, pRS315-IQG1-GST) and RNY2595 (iqg1Δ MYO1-GFP, pRS315-IQG1[Δ2-411]-GST) were grown in SC-Leu media at 23°C and then fixed and stained for actin and DNA. (B) Abnormal constriction of the Myo1-GFP ring in iqg1-CHDΔ mutant. Cells of the strains RNY2596 (iqg1Δ MYO1-GFP CDC3-mCherry, pRS315-IQG1-GST) and RNY2597 (iqg1Δ MYO1-GFP CDC3-mCherry, pRS315-IQG1[Δ2-411]-GST) were grown in SC-Leu media at 23°C and then imaged by time-lapse microscopy at 23°C with a 1-min interval. Arrowheads indicate septin-hourglass splitting. (C) PS formation in iqg1-CHDΔ mutant. PS of the strains listed in A were visualized by transmission EM and the orientation of the PS was quantified as in Fig. 5 D.