Studies on the chemical cues involved in larval metamorphosis and settlement in marine invertebrates.

研究了大污染生物在多毛藻（serpulid polychaete Hydroides ezoensis）幼虫蜕变和沉降过程中的各种化学信号。我们从同一种成虫管团的MeOH提取物中分离鉴定了一种新的单酰基甘油，1-(4Z, 7Z, 10Z, 13Z, 16Z, 19Z)-二十二碳六烯醇甘油，作为ezoensis幼虫的变态诱导物质。这一结果表明，该物质归因于该物种表现出的群居性。各种相关化合物，如游离脂肪酸或其甘油，也被检查了他们的能力，以诱导蝌蚪的幼虫变态。在游离脂肪酸中，只有不饱和游离脂肪酸诱导幼虫的变态，诱导变态的活性取决于游离脂肪酸不饱和键的存在和数量。甘油比FFA活性高。在人工变态诱导剂中，l -3,4-二羟基苯丙氨酸（L-DOPA）和神经递质肾上腺素诱导了棘棘棘虫的幼虫变态，L-DOPA的对映体D-DOPA在脊椎动物中无活性，也在较低程度上诱导了幼虫变态。结果表明，不同类型的多巴胺受体可能参与了棘猴幼体的变态过程。在几种肾上腺素激动剂中，α_1、α_2和β型受体的激动剂均表现出明显的特异性。结果表明，不同类型的肾上腺素受体可能参与了棘棘棘虫幼虫的变态过程，海水中过量的K^+和Ca^<2+>离子也会诱导棘棘棘虫幼虫的变态，并呈剂量依赖性。海水中Ca^<2+>的减少阻断了L-DOPA对幼虫变态的诱导，说明过量Ca^<2+>诱导的幼虫变态可能位于比L-DOPA更低的级联流。

Various chemical signals involved in larval metamorphosis and settlement of macrofouling organisms were examined for serpulid polychaete Hydroides ezoensis. We isolated and indentified a new monoacyl glycerol, 1-(4Z, 7Z, 10Z, 13Z, 16Z, 19Z)-docosahexaenoyl-glycerol as a metamorphosis inducing substance of larvae of H.ezoensis form MeOH extract of adult tube clumps of the same species. This result indicates that this substance attributes the gregarious settlement exhibited by this species. Various related compounds such as free fatty acids or their glycerids were also examined for their abilities to induce larval metamorphosis of H.ezoensis. In FFA's, only unsaturated FFA's induced larval metamorphosis and the metamorphosis-inducing activities depend on the presence and the number of unsaturated bonds of FFA's. Glycerids exhibited higher activities than FFA's.Among artificial metamorphosis inducer, L-3,4-dihydroxyphenylalanine (L-DOPA) and neurotransmitter epinephrine induced larval metamorphosis in H.ezoensis.Enantiomer of L-DOPA, D-DOPA, which is inactive in vertebrates, also induced larval metamorphosis in lower degree. This result indicates the possibility that dopamine-receptor of different type from that of vertebrates may be involved in larval metamorphosis in H.ezoensis.Among several agonists of epinephrine tested, any specific agonists of α_1, α_2, or β type receptor exhibited clear results. This result indicates the possibility that adrenaline-receptor of different type from that of vertebrates may be involved in larval metamorphosis in H.ezoenssis.Excess K^+ and Ca^<2+> ion in seawater also induced larval metamorphosis in dose dependently. Decrease of Ca^<2+> in seawater blocked the induction of larval metamorphosis by L-DOPA, indicating that induction of larval metamorphosis induced by excess Ca^<2+> may locate lower stream of cascades than that of L-DOPA.