Evidence for a symmetrical uptake of fluorescent dyes through electro‐permeabilized membranes of Avena mesophyll protoplasts

Abstract

The permeability properties of the plasmalemma of oat mesophyll protoplasts during the application of an electric field pulse were studied. As a measure, the intracellular fluorescence resulting from the uptake of DNA and RNA staining dyes (ethidium bromide, berberine hemisulfate), showing a very low rate of permeation across the plasmalemma of intact protoplasts, were determined microphotometrically. The results show that membrane breakdown, caused by supercritical field strengths, leads to an uptake of the charged dyes only via those membrane sites oriented toward the positive electrode. Mechanisms possibly underlying this asymmetrical uptake as well as its practical application are discussed.