Effects of pulsed electric field number on embryonic development of Oryzias latipes

The paper describes the effects of 50 to 110 nanosecond pulsed electric field (PEF) on the embryonic development of the Oryzias latipes (medaka fish). PEF provides the possibility of controlling membrane transport process and functions of biological cells. However, the details of short nanosecond order pulse effects have not been fully understood. Currently, the effects of PEF have been mostly studied in-vitro, while, there are interest about in-vivo effects. The goal of the current study is to find the effects of short pulsed electric field in-vivo during embryo development to control cell proliferation and differentiation. A pulsed power modulator using a magnetic pulse compression circuit (MPC) is employed to generate 0.5 to 30 kV pulses with 50 to 110 nanosecond pulse durations. Fertilized eggs of d-rR medaka strain are used. The age of the experimental eggs are 6 hour post fertilization (hrPF), 1 day, and 2 days old. In each experiment, a single medaka egg (about 1.2 mm diameter) is set at the middle of a 2 mm or 4 mm cuvette. Electric pulses are applied with several different conditions. Pulse numbers are set to 1 to 40 shots with one pulse per second (PPS) rate. The conductivity of the medium (w.o. Hanks´ balanced salt solution) is adjusted by adding distilled water to 1 or 15 mS/cm. Furthermore, two kind of pulse widths of 50 and 110 ns are applied. The embryos are observed under a fluorescent microscope. Propidium Iodide (PI) is used to study electroporative uptake kinetics of the embryo cells. By applying 110 ns electric pulses, extensive damage of eggs are observed. For shorter 50 ns width pulses and low electric field, delayed hatching consistent with electric field intracellular interaction is observed, whereas stronger electric field affected the eggs immediately after the pulse and those eggs could not survive and died a few days later. Some abnormal embryo growths are observed under high conductivity condition.