FIGURE 10.

Hemifusion video images. Vesicles had moderate net charges (24%). Time sequence of the images: (A) Before the vesicles contacted. (B) Two vesicles contact (at 0 ms). (C) Contact zone formed (at 33 ms). (D) Stable contact (at 66 ms). (E) Contact area color changed from yellow to red (at 99 ms). At the same time, red fluorescence appeared on the green vesicle, showing that Rh-PE diffused from the negatively- to the positively-charged vesicle. (F–I) Images at 132, 165, 231, and 330 ms after contact. (J) At 660 ms after contact; the green color was significantly quenched and the red color increased along the vesicle contact area. Hemifusion as a stable final state is commonly seen with vesicles having an intermediate content of charged lipid.