Electrically fused-egg induction and its development in the goldfish, Carassius auratus

In this study, we report the induction of cell fusion between two fertilized eggs and viable chimeric fish from the fused egg in goldfish. Chemical fusion by polyethylene glycol between denuded fertilized egg induced egg adhesion but rarely egg fusion. This treatment seemed not suitable for egg fusion, because of tight adhesion between vitelline membrane and surrounding matrix. Electrically fertilized egg fusion was successfully induced at the rate of almost 100% under conditions of 400V/cm, 1 MHz dielectrophoresis pulse for 3 seconds and a successive, 750V/cm, 10 microseconds fusion pulse. The treatment had to be applied to the egg in the calcium-free low electrolyte medium within 20 min of fertilization at 20 degrees C. Small numbers of fused eggs developed into young chimeric fish, and the different cells originating from two eggs survived together as an individual.