Genetic studies on the pacific abalone. XI. Gynogenesis with ultraviolet ray irradiated sperm in the pacific abalone.

Abstract

Probable usefulness of induced gynogenesis followed by diploidization has been discussed as a part of breeding technologes for genetic improvement of aquacultural organisms. The present study examined sets of conditions of treating spermatozoa by ultraviolet ray irradiation for effective induction of gynogenesis in the pacific abalone Haliotis discus hannai on the basis of observations on fertilization rate of the eggs, survival rate and chromosome constitutions of the zygotes. An aliquot of sperm suspension, placed in a plastic petri dish ion-sputtered in advance, was exposed to irradiation of ultraviolet ray of 42 erg per mm2 per s for varying durations. Immediate after the irradiation, the treated spermatozoa suspension was added to egg suspension at room temperature for fertilization. Irradiation of spermatozoa by ultraviolet ray of the above intensity for 30 to 60s successfully induced gynogenesis, indicating the high frequency occurrence of the haploid zyogtes consonant with the recovery in survival rate of zygotes, called Hertwig effect.