Fig. 6. Effects of actin-modifying reagents on the final extents of syncytium formation. (A) Syncytium formation for Sf9^Op1D cells treated with the cell-permeable actin-depolymerizing reagents LatA (2 µM, bar 2) and CD (0.1 µM, bar 3), and actin-polymerizing reagent Jasp (0.5 µM, bar 4), and for the untreated cells (bar 1). LatA was applied 30 minutes before a fusion-triggering low-pH pulse. CD and Jasp were applied immediately after the pulse (see Materials and Methods). (B) The membrane-impermeable actin-polymerizing reagent phalloidin that was delivered into Sf9^Op1D cells by their fusion with phalloidin-loaded erythrocyte ghosts inhibited syncytium formation. In the control experiments we used unloaded erythrocyte ghosts. (A,B) Fusion was triggered by a 1-minute application of pH 4.9 medium. Syncytium-formation extents were scored 30 minutes later and presented as means+s.e. (n3).