Chemical defenses of the sacoglossan mollusk Elysia rufescens and its host alga Bryopsis sp.
Chemical defenses of the sacoglossan mollusk Elysia rufescens and its host alga Bryopsis sp.
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DOI：
10.1023/a:1012287105923
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发表时间：
2001-11-01
影响因子：
2.3
通讯作者：
Scheuer, PJ
中科院分区：
文献类型：
--
作者：
Becerro, MA;Goetz, G;Scheuer, PJ
棘舌动物是一组蛇鳃软体动物，是许多次生代谢物的来源；然而，很少有例子表明，这些化合物的防御生态作用已被实验证明。本文研究了棘舌鱼（saclossan Elysia rufescens）及其食藻苔藓藻（Bryopsis sp.）对天然鱼类捕食者的威慑性能。Bryopsis sp.产生kahalalide F，这是一种主要的沉积肽，由糖蛋白积累，在体外对几种癌细胞系显示出细胞毒性。我们的数据表明，Bryopsis sp.和Elysia rufescens都具有化学保护作用，可以抵御鱼类捕食者，正如它们的提取物在自然浓度下的威慑特性所表明的那样。在生物测定指导下，我们观察到Bryopsis sp .的抗掠食性化合物存在于含有沉淀肽kahalalide f的丁醇和氯仿部分，这两个部分都含有Elysia rufescens的抗掠食性化合物只存在于二氯甲烷部分。进一步的生物测定引导分离导致分离卡哈拉利德F作为唯一的化合物负责的阻吓性能的骶骨聚糖。我们的数据表明，卡哈拉胺F对苔藓虫和苔藓虫都有保护作用。以及来自鱼类捕食的红叶Elysia rufescens。这是首次报道从饮食中提取的沉积肽在舌聚糖中用作化学防御。
Sacoglossans are a group of opisthobranch mollusks that have been the source of numerous secondary metabolites; however, there are few examples where a defensive ecological role for these compounds has been demonstrated experimentally. We investigated the deterrent properties of the sacoglossan Elysia rufescens and its food alga Bryopsis sp. against natural fish predators. Bryopsis sp. produces kahalalide F, a major depsipeptide that is accumulated by the sacoglossan and that shows in vitro cytotoxicity against several cancer cell lines. Our data show that both Bryopsis sp. and Elysia rufescens are chemically protected against fish predators, as indicated by the deterrent properties of their extracts at naturally occurring concentrations. Following bioassay-guided fractionation, we observed that the antipredatory compounds of Bryopsis sp, were present in the butanol and chloroform fractions, both containing the depsipeptide kahalalide F. Antipredatory compounds of Elysia rufescens were exclusively present in the dichloromethane fraction. Further bioassay-guided fractionation led to the isolation of kahalalide F as the only compound responsible for the deterrent properties of the sacoglossan. Our data show that kahalalide F protects both Bryopsis sp.. and Elysia rufescens from fish predation. This is the first report of a diet-derived depsipeptide used as a chemical defense in a sacoglossan.