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

这项研究已经开始阐明鲍鱼幼体定居和变态的天然诱导剂。然而，由于鲍鱼孵化季节的限制，与鲍鱼孵化季节不同的亚热带腹足类尼罗罗非鱼也进行了测试。经过多次试验，我们最终建立了用于此目的的生物测定方法如下：1)将样品溶液(约5-300微升)加入平底玻璃试管(phi2.5×15 cm)。2)溶剂挥发后加入35ml硫酸链霉素和青霉素G钾各含150 mg/L的高压灭菌海水。3)引入约10条幼虫，每条幼虫在1-8天后进行显微镜观察。首先测定了珊瑚红藻石藻石藻顶壳变态的γ-氨基丁酸和甲醇提取物。本研究是尼罗罗非线虫幼虫变态的首次化学研究。海藻提取液INDU…当提取物的剂量相当于风干藻类的5-15 mg时，更多的冰冻幼虫变态(约80%)。GABA也在10^&lt；-5-3&gt；M处诱导变态，其作用方式明显不同[Nippon Suisan Gakkaishi，59,1261(1993)]。与多不饱和脂肪酸相比，藻类活性成分被发现以较低的极性组分洗脱，其中一些已被报道可诱导一些鲍鱼和一些管虫幼虫的变态。频繁的台风袭击造成了获取试验幼虫的困难，导致有效成分的分离不完整(S)。从藻类提取物中提取的低极性组分被发现可以诱导皱纹盘藻和细纹夜蛾的变态。由于生物活性测定的数量有限，活性成分(S)的分离还没有完成，要等到下一季才能完成。GABA首次被证明能使圆盘海鞘和海参幼虫变态，但对杂色海鞘没有影响。我们中的一位(Akutsu)已经获得了成功地将GABA应用于鲍鱼苗木生产的实验结果。较少

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