Electroporation - A new technique for transferring genes into plants or animal cells is that of electro po ration.

Electroporation, a technique using electrical fields to make protoplasts temporarily permeable to DNA, offers an effective alternative to vectors.

In electroporation plant cell protoplasts are suspended in a small chamber with electrodes at opposite ends.

The suspension medium contains the DNA or other material to be inserted into the cells. Pulses of high voltages are applied to the electrodes.

Yet these same conditions must make pores that are reversible and temporary.

Reversible pores are induced by a potential of about 1 volt across a membrane, but the exact conditions that will induce this voltage and make it work correctly depend on the size of the cell, the composition of the cell membrane, the composition of the suspending solution, and the temperature.

Applying a 40-fL sec pulse of electric field at 2 kV/cm to red blood cells causes an exchange of sodium and potassium across their plasma membranes.

Pores that allow this exchange reseal in seconds or fractions of a second at normal temperatures (37°C) but remain open for several minutes at 0°C.

These are representative conditions: Ou-Lee arid his associates tried several variations to obtain optimum results.

They held the protoplasts at 0°C for ten minutes, then placed them in culture medium.

Two days later, they detected cat activity in extracts of the protoplasts.

Electroporation thus may become the method of choice for inserting DNA into plant cells.

Getting this DNA to incorporate efficiently into the plant genome, especially into specified places in the plant genome, will probably still require vectors as described earlier.