High electric field effects on the cell membranes of Halicystis parvula |
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Authors: | R Benz U Zimmermann |
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Institution: | (1) Fakultät für Biologie, Universität Konstanz, Postfach 5560, D-7750 Konstanz, Federal Republic of Germany;(2) Arbeitsgruppe Membranforschung am Institut für Medizin der Kernforschungsanlage Jülich, Postfach 1913, D-5170 Jülich, Federal Republic of Germany |
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Abstract: | The electrical breakdown behavior of the giant algal cell Halicystis parvula was studied in order to predict the optimum conditions for electrically induced cell-to-cell fusion. Using the charge pulse technique, the membranes were charged at different pulse lengths to the maximum voltage Vc. Because of a reversible, high-conductance state of the membrane (electrical breakdown), it was not possible to exceed the critical membrane breakdown potential. The breakdown voltage exhibited a strong dependence on the charging time (pulse length) between 10 s and 100 s. Below 10 s the breakdown voltage of the two membranes, tonoplast and plasmalemma, assumed a constant value of about 1.9 V, whereas above a pulse length of about 100 s the breakdown voltage was nearly constant with a value of about 0.6 V. The extreme values for the breakdown voltage at very short and at very long charging times agree fairly well with results which have been obtained on cells of Valonia utricularis and planar lipid bilayer membranes. However, the pulse length dependence of the breakdown voltage was found to be quite different in H. parvula. In addition, the membrane conductance increase during breakdown in H. parvula cells is much more pronounced than in membranes of V. utricularis, but similar to lipid bilayer membranes. From this result it is suggested that the membrane structure of H. parvula is quite different from V. utricularis (larger lipid domains). |
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Keywords: | Cell fusion Charge pulse technique Electrical breakdown Halicystis Membrane potential Pulse length dependence |
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