BIOLOGICAL ASPECTS OF RESTING EGG FORMATION, DIAPAUSE AND HATCHING OF SMALL SPECIES ROTIFERS AND ITS APPLICATION TO MASS PRESERVATION TECHNOLOGY

休眠卵形成机制在收集的20个轮虫菌株中，有8个菌株具有有性繁殖能力。在30℃和16ppt的盐度下，它们的混合百分比超过30%。夏威夷和兰卡维品系的休眠卵形成旺盛。高效液相分析表明，轮虫体内含有γ-氨基丁酸和5-羟色胺，提示它们可能作为神经递质存在于轮虫体内。我们用从Koshiki菌株获得的雄蜂识别信息素的多克隆抗体进行了几次检测。该抗体与除Hamana株和西班牙株外的其他毒株结合良好。当雌性与抗体结合时，品系间雄性对雌性的配偶识别也受到同样的抑制。这表明，其他小种轮虫品系的污染不会减少种群中雄性配偶的识别。休眠卵的大规模生产和保存使用夏威夷和哈马纳品系，我们在以上获得的最佳条件下进行了休眠卵的大规模生产。采用半连续培养的方法，可在较长时间内提高诱导效果。夏威夷品系的休眠卵产量分别为7、5和110万粒/500升，Hamana品系的休眠卵产量分别为65、79和2700万粒/500升。休眠卵冷冻干燥后在4℃下大量保存，孵化率可达50-60%。

Mechanism of resting egg formationAmong collected twenty rotifer strains, eight strains had sexual reproductive ability. These exhibited the percent mixis at more than 30% under 30℃ and 16 ppt salinity. Resting egg formation was vigorous with Hawaii and Langkawi strains. The HPLC analysis clarified that gamma-aminobutyric acid and 5- HT are present in rotifers, suggesting that these may function as neurotransmitters in rotifers. We conducted several assays using the polyclonal antibody of male mate recognition pheromone obtained from Koshiki strain. The antibody binded well with strains except Hamana and Spanish strains. Male mate recognition to females among strains were equally inhibited when females were bound with the antibody. These suggest that the contamination of other small-species rotifer strains will not reduce the male mate recognition in the population.Mass production and preservation of resting eggsUsing Hawaii and Hamana strains, we conducted mass production of resting eggs under optimal condition obtained above. Semicontinuous culture method was used to enhance the mixis induction for a longer period of time. For Hawaii strain, the resting egg harvest in three tanks were 7, 5 and 1.1 (million ) resting eggs per 500 liter tank, and it was 65, 79 and 27 million resting eggs for Hamana strain. Resting eggs were mass preserved at 4oC after lyophilization, and we obtained 50-60% hatching.