Triploidization of the Pacific Abalone with Temperature and Pressure Treatments*1

Abstract

Progress in research on chromosome manipulation of aquatic animals has been reviewed by one of the present authors. Along with the context, successful induction of gynogenesis in the pacific abalone was reported before. The present work attempted to induce triploid animals in the pacific abalone Haliotis discus hannai as a part of a series of genetic and breeding researches on the species. Egg and sperm specimens, obtained through stimulating animals with sterilized and heated sea water, were used for insemination. Normal developmental processes of inseminated eggs were observed to determine proper times for starting the treatments of eggs for inducing triploid animals. Cold, hot, or hydrostatic pressure shock was applied to inhibit releases of first and/or second polar bodies, Ploidy status of zygotes was examined by karyotype observation as well as chromosome counts. After examining sets of conditions of times, intensity, and duration of treatments, it became evident that treating eggs at 3°C of cold shock for 15 min 12 or 32 min after insemination, at 35°C of hot shock for 3 min or at 200 kg/cm2 of hydrostatic pressure shock for 5 min 7 or 22 min after insemination can inhibit release of first or second polar bodies and result in induction of thousands of triploid animals of the pacific abalone in quite a high frequency. © 1986, The Japanese Society of Fisheries Science. All rights reserved.