Chemical Studies of Natural Inducers of Larval Settlement and Metamorphosis for Two Species of Phestilla (Opisthobranchia)

本研究的目的是分离和鉴定两个近缘种裸枝吸虫幼虫定居和变态的天然化学诱导物。这两个物种捕食珊瑚，但有不同的寄主偏好。活性分子是强有力的形态因子，对裸枝动物的发育有着深远的影响。将研究以Porite珊瑚为食的Sibogae Phstilla sibogae和以Tubasrea spp等树叶珊瑚为食的P.Blackobrachia的天然诱导剂。活性化合物的分离将通过活性提取物的层析分离和随后的幼虫沉降生物测试来确定哪些组分会导致沉降和变态。一旦纯化，核磁共振和其他光谱方法将被用来阐明活性诱导剂的结构。不同种类的珊瑚的化学特征也可以通过分析高效液相色谱法进行检查，以确定相关珊瑚中是否存在相同的活性化合物。比较两种近缘裸目动物的定居线索将为专门的海洋无脊椎动物提供关于宿主偏好的生态学和进化以及对可溶化学线索的反应的信息。

The objective of this research is to isolate and characterize the natural chemical inducers of larval settlement and metamorphosis for two related species of the nudibranch Phestilla. The two species consume scleractinian corals, but have different host preferences. The active molecules are potent morphogens, and profoundly influence the development of the nudibranchs. Natural inducers will be studied for Phestilla sibogae, which feeds on Porites corals, and P. melanobrachia, which feeds on dendrophyllid corals such as Tubastrea spp. Isolation of active compounds will be carried out by chromatographic separations of active extracts with subsequent bioassays of larval settlement to determine which fractions induce settlement and metamorphosis. Once purified, NMR and other spectroscopic methods will be used to elucidate the structures of active inducers. The chemical profiles of different species of corals can also be examined by analytical HPLC to determine whether the same active compounds are present in related corals. Comparison of the settlement cues for two related species of nudibranch will provide information on the ecology and evolution of host preference and the responses to soluble chemical cues for specialist marine invertebrates.