低温処理によるフクトコブシの人為3倍体作出〔英文〕

概要

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A set of optimum conditions of the cold shock for inducing triploid was determined in the abalone Haliotis diversicolor diversicolor. The observations on the normal developmental pro-cesses indicated that the inseminated egg released the first and the second polar bodies and began the first cleavage approximately 5, 20 and 40 min, respectively after insemination at about 25°C water temperature. A series of cold shock treatments at 3°C for 10 and 15 min duration, initiated at different times (3-21 min) after insemination, showed bimodal distribution of frequency of occurrence of t iploid animals as assessed by counting the chromosome number. Modes of frequency distribution of occurrence of triploid animals were found 6 and 15-18 min after in-semination. These were interpreted to represent two kinds of triploidy, resulting from retention of the first or the second polar body, respectively. Among cold shock experiments at different temperatures (3, 6 and 9°C), the treatment at 9°C for 10 min duration gave the highest yield of normal larvae (about 70%) with appreciable induction of triploidy (about 60-70%).