The first report of electrofusion in 1979  

Senda, M., J. Takeda, S. Abe and T. Nakamura. Induction of cell fusion of plant protoplasts by electrical stimulation. Plant Cell Physiology 20:1441-1445

Electrofusion was discovered during the study of electrophysiology of plant protoplasts and derived from a calcium dependent, reversible membrane opening upon stimulation by electrical pulse when insertion of microelectrode was made into protoplasts.

This work is the earliest (1979) and a milestone of electrofusion. Two years later (1981), Zimmermann et al published more efficient method to fuse protoplasts by electrical stimulation . In our earliest work, we pointed out the importance of Ca 2+ ions in electrofusion, and in later work we confirmed a calcium involved mechanism in electrofusion. -> References

In later works of us, we revealed that the electrofusion process can be divided into three phases: 1. initial induction: 2. development (rounding up): 3. recovery (references 7-9). We demonstrated that contributions of surface charges were not important at these stages while calcium ions were (7,8). In step 2, the cytoskeleton will be involved(7,9). It was noted that La ions, as an antagonist against Ca ions, strongly inhibited induction of electrofusion while promoted the development of fusion (8).

La ions inhibit initiation of electrofusion while promoting rounding up of fusion products (8). We further revealed that La ions can reversibly neutralize the surface charges but irreversibly the induction. In the presence of La, the electrophoretic mobility and dielectrophoresis of protoplasts were greatly reduced to zero and it was recovered to the original after removing the La medium. But, with these electrophoretically recovered protoplasts induction of electrofusion remained inhibited. In addition in the presence of La ions when fusion was once induced the rounding up of the fusion products was greatly facilitated. La ions exerted dual effects on electrofuion processes.

Various polyvalent cations including hexaaminecobalt and spermidin could facilitate rounding up of electrofused protoplasts but not the induction.Together with other evidences, we concluded that induction of electrofusion requires Ca ions and surface charges of protoplasts are not important and that the initial induction and the development of electrofusion occur with different mechanisms and can be separated.


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