Chemical Studies on Larval Settlement and Metamorphosis of the Abalone Haliotis spp.

本研究初步阐明了鲍鱼幼体附着和变态的自然诱导因子。然而，由于鲍鱼的孵化季节有限，亚热带腹足类Trochus niloticus的孵化季节与鲍属不同，也进行了测试。经过多次试验，我们最终建立了如下的生物测定法：1）将样品溶液（约5-300穆尔）加入平底玻璃试管（φ 2.5 × 15 cm）中。2)蒸发溶剂后，加入35毫升高压灭菌的海水，其中硫酸链霉素和青霉素G钾各150毫克/升。3)将10只左右的尼罗罗非鱼幼鱼放入实验室，1-8天后，对每只幼鱼进行显微观察。首先，用γ-氨基丁酸（GABA）和珊瑚红石褶藻（Lithophyllum okamurae）的甲醇提取物对尼罗罗非鱼的变态进行了研究。本研究首次对尼罗罗非鱼幼虫变态进行了化学研究。海藻提取物工业 关于我们 在相当于5-15 mg风干的幼虫的提取物剂量下，幼虫变态（约80%）。GABA在10 μ M时也诱导变态<-5--3>。作用方式彼此明显不同[Nippon Suisan Gakkaishi，59，1261（1993）]。发现藻类活性成分以比多不饱和脂肪酸极性小的组分洗脱，其中一些已报道诱导一些鲍和一些管虫幼虫变态。频繁的台风袭击给获得用于测试的幼虫带来了麻烦，导致有效成分的分离不完全。发现来自藻提取物的极性较小的组分诱导盘状海蜇和西氏海蜇的变态。由于生物测定的数量有限，活性成分的分离尚未完成，要等到下一个季节。GABA首次被证明能使铁饼蟹和西氏蟹的幼虫变形，但对杂色蟹没有影响。我们之一（Akutsu）已成功地将GABA应用于鲍鱼育苗生产的实验结果。少

This study has begun to clarify the natural inducers for larval settlement and metamorphosis of the abalone Haliotis spp. However, because of the limited hatching season for the abalone, the subtropical gastropod Trochus niloticus, whose hatching season is different from that of Haliotis spp., was also tested. After many trials we finally established a bioassay for this purpose as follows : 1) Sample solution (about 5-300 mul) was added into a flat bottom glass test tube(phi2.5 x 15cm). 2) After evaporating the solvent was added 35 ml of autoclaved sea water containing 150 mg/l each of streptomycin sulfate and penicillin G potassium. 3) About ten larvae were introduced and each larvae was microscopically observed after 1-8 days.First we tested gamma-Aminobutyric acid (GABA) and MeOH extract of the coralline red alga Lithophyllum okamurae for metamorphosis of the top shell T.niloticus. This study was the first chemical study on larval metamorphosis of T.niloticus. The algal extract indu … More ced larval metamorphosis (about 80%) at doses of the extracts equivalent to 5-15 mg of the air-dried alga. GABA also induced the metamorphosis at 10^<-5--3>M.The mode of action was clearly different from each other [Nippon Suisan Gakkaishi, 59, 1261 (1993)]. The algal active principle was found to be eluted in less polar fractions than polyunsaturated fatty acids, some of which have been reported to induce metamorphosis of some Haliotis and some tube worm larvae. Frequent typhoon attacks caused troubles in obtaining the larvae for the test, resulting in incompletion of the isolation of the active principle(s).The less polar fractions from the algal extract was found to induce the metamorphosis of H.discus and H.sieboldi. Because of limited numbers of bioassay, isolation of the active principle(s) has not been finished and is to be waited till next season.GABA was, for the first time, shown to metamorphose the larvae of H.discus and H.sieboldi, although no effect on H.diversicolor aqutilis. One of us(Akutsu) has got experimental results for a successful application of GABA to seedling production of the abalones. Less