Kubanek Julia, Whalen Kristen E, Engel Sebastian, Kelly Sarah R, Henkel Timothy P, Fenical William, Pawlik Joseph R
School of Biology and School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA, 30332-0230, USA.
Center for Marine Science, University of North Carolina at Wilmington, Wilmington, NC, 28409, USA.
Oecologia. 2002 Mar;131(1):125-136. doi: 10.1007/s00442-001-0853-9. Epub 2002 Mar 1.
Despite their high nutritional value and a lack of physical defenses, most marine sponges appear to be minimally affected by predators, competitors, and fouling organisms, possibly due to sponge chemical defenses. In the last 15 years, several triterpene glycosides have been isolated from sponges, but their ecological or physiological roles are largely unknown. We tested triterpene glycosides from Erylus formosus and Ectyoplasia ferox, Caribbean sponges belonging to two different orders, in field and laboratory assays for effects on fish feeding, attachment by potential biofilm-forming bacteria, fouling by invertebrates and algae, and overgrowth by neighboring sponges. Formoside and other triterpene glycosides from Erylus formosus deterred predation, microbial attachment, and fouling by invertebrates and algae. Triterpene glycosides from Ectyoplasia ferox were found to be antipredatory and allelopathic. Thus, triterpene glycosides in these sponges appear to have multiple ecological functions. Tests with different triterpene glycosides at several concentrations indicated that small differences in molecular structure affect ecological activity. In order to establish whether triterpene glycosides could be involved in water-borne versus surface-mediated interactions, the presence of triterpene glycosides in the seawater surrounding live sponges was measured using two in situ sampling methods followed by HPLC and NMR spectral analysis. Water-borne triterpene glycosides were below detection limits for both species. However, top sponge layers and swabs of the surfaces of both sponges contained sufficiently high concentrations of triterpene glycosides to deter bacterial settlement and fouling of Erylus formosus surfaces and overgrowth of Ectyoplasia ferox by neighboring sponges. Enemies of these sponges appear to be deterred by surface contact of triterpene glycosides rather than by water-borne interactions. The dual strategy of employing one group of compounds for multiple purposes and minimizing the loss of compounds into seawater suggests that these organisms utilize chemical defenses with efficiency.
尽管大多数海洋海绵具有很高的营养价值且缺乏物理防御，但它们似乎受捕食者、竞争者和污损生物的影响极小，这可能归因于海绵的化学防御。在过去15年中，已从海绵中分离出几种三萜糖苷，但其生态或生理作用在很大程度上仍不清楚。我们对来自加勒比海的属于两个不同目的海绵——美丽艾氏海绵（Erylus formosus）和凶猛外胚层海绵（Ectyoplasia ferox）中的三萜糖苷进行了野外和实验室试验，以研究其对鱼类摄食、潜在形成生物膜的细菌附着、无脊椎动物和藻类污损以及相邻海绵过度生长的影响。美丽艾氏海绵中的甲藻糖苷和其他三萜糖苷可阻止捕食、微生物附着以及无脊椎动物和藻类的污损。发现凶猛外胚层海绵中的三萜糖苷具有抗捕食和化感作用。因此，这些海绵中的三萜糖苷似乎具有多种生态功能。对不同浓度的不同三萜糖苷进行的试验表明，分子结构上的微小差异会影响生态活性。为了确定三萜糖苷是否参与水介导与表面介导的相互作用，我们使用两种原位采样方法，随后进行高效液相色谱（HPLC）和核磁共振（NMR）光谱分析，测量了活海绵周围海水中三萜糖苷的存在情况。两种海绵的水介导三萜糖苷均低于检测限。然而，两种海绵的顶部海绵层和表面拭子中三萜糖苷的浓度足够高，足以阻止细菌在美丽艾氏海绵表面沉降和污损，以及阻止相邻海绵对凶猛外胚层海绵的过度生长。这些海绵的天敌似乎是被三萜糖苷的表面接触所阻止，而不是水介导的相互作用。将一组化合物用于多种目的并尽量减少化合物向海水中流失的双重策略表明，这些生物有效地利用了化学防御。
