Papers Published

  1. Marszalek, P. and Tsong, T. Y., Cell Fission and Formation of Mini Cell-Bodies by High-Frequency Alternating Electric-Field, Biophysical Journal, vol. 68 no. 4 (1995), pp. 1218-1221 .
    (last updated on 2007/11/30)

    We report the use of high frequency alternating electric fields (AC) to induce deformation of sea urchin eggs, reading to budding of membrane Vesicles or fission of cells. Several mini cell bodies can be prepared from a single egg by carefully manipulating the frequency and amplitude of the AC field and the ratio between the interelectrode spacing and the cell diameter, alpha. alpha values between 2.2 and 3.5 have been found to be optimal for inducing fission of sea urchin eggs. In a typical experiment, a sea urchin egg (diameter = 75 mu m), suspended in a low ionic medium (conductance < 2 mS/m), was located under the microscope between two platinum wire electrodes, separated by a distance of approximate to 200 mu m. A medium strength AC field (<100 V/cm at 2 MHz) was applied to attract the egg to one of the two electrodes via dielectrophoresis. This process took place in a few seconds. The Voltage was then slowly increased to approximate to 1000 V/cm over approximate to 30 s. The cell elongated and separated into two fragments, the larger one containing the nucleus. When the field was turned off, the mother cell and the daughter vesicle retracted to form spherical mini cell bodies that appear to be stable as assessed by the absence of swelling for the duration of the experiment (approximate to 15 min). This indicates that membranes of these mini cell bodies were not leaky to ions and small molecules. This procedure could be repeated a few times to make several mini cell bodies from a Single egg. With practice, several mini cell bodies could also be prepared in a single fission experiment by adjusting the field parameters and the a value. Cell fission is a result of the mechanical stress produced by the AC field. These procedures may be used to prepare mini membrane Vesicles for voltage clamp experiments or to perform microsurgical manipulation of cells, embryos, or chromosomes.