Occurrence of 16:2(n-4) and 18:2(n-4) fatty acids in the lipids of the hydrothermal vent shrimps Rimicaris exoculata and Alvinocaris markensis : nutritional and trophic implications
Occurrence of 16:2(n-4) and 18:2(n-4) fatty acids in the lipids of the hydrothermal vent shrimps Rimicaris exoculata and Alvinocaris markensis : nutritional and trophic implications
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热液喷口虾 Rimicaris exoculata 和 Alvinocaris markensis 脂质中 16:2(n-4) 和 18:2(n-4) 脂肪酸的存在：营养和营养影响
DOI：
10.3354/meps156167
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发表时间：
1997
影响因子：
2.5
通讯作者：
J. Sargent
中科院分区：
文献类型：
--
作者：
D. Pond;D. Dixon;M. V. Bell;A. Fallick;J. Sargent
从大西洋中部海脊的蛇坑和TAG热液喷口现场采集了2种喷口对虾的成体标本。脂肪酸分析表明，大斑鱼脂肪中含有丰富的16：2(n-4)和18：2(n-4)脂肪酸，其中消化腺中的比例最高，分别为14.5%(16：2(n-4)和23.8%18：2(n-4))。从大斑鱼腹肌提取的脂肪中也含有这些脂肪酸，但比例较低[2.0%16：2(n-4)和14.5%18：2(n-4)]。相反，从同一组织中提取的脂肪含有相对较低的(n-4)脂肪酸比例(1.9-3.0%)，但大量富含光养、微浮游生物标志物20：5(n-3)和22：6(n-3)。GC-IRMS(GC-IRMS)分析n-4二烯脂肪酸的delta13C值为-11.0~-11.4o/oo，这与脂肪酸来源于化学合成的固定碳是一致的。相比之下，光养微型浮游生物特有的脂肪酸含量较轻，20：4(n-6)、20：5(n-3)和22：6(n-3)分别为-17.1、-17.3和-15.8o/oo。在所有样品中均检测到20：2Delta5、13和22：2Delta7、15的非亚甲基中断二烯(NMIDs)，但以Re exoculata的含量最高。(n-4)二烯和NMID符合该物种细菌来源的16：1(n-7)和18：1(n-7)脂肪酸的实质性饮食输入。因此，这些结果与Exoculata采用食菌性营养模式一致，而A.markens本质上是一种食腐动物(尸食性)，表明这两个物种在食物供应方面并不是直接竞争的。
Adults of 2 species of vent shrimp, Rimicaris exoculata and Alvinocaris markensis, were sampled from the Snake Pit and TAG hydrothermal vent sites on the mid-Atlantic ridge. Fatty acid analyses indicated high abundances of 16:2(n-4) and 18:2(n-4) in the lipids of R. exoculata, with the highest proportions of these fatty acids detected in the digestive gland [14.5% 16:2(n-4) and 23.8% 18:2(n-4)]. Lipid extracted from abdominal muscle of R. exoculata also contained these fatty acids, although in lower proportions [2.0% 16:2(n-4) and 14.5% 18:2(n-4)]. By contrast, lipid extracted from the same tissues in A. markensis contained relatively low proportions of (n-4) fatty acids (1.9 to 3.0%), but was substantially enriched in the phototrophic, microplanktonic biomarkers 20:5(n-3) and 22:6(n-3). GC-IRMS (gas chromatography with isotope ratio mass spectrometry) analysis of the (n-4) dienoic fatty acids established delta13C values of -11.0 to -11.4o/oo which is consistent with the fatty acids being derived from chemosynthetically fixed carbon. By contrast, those fatty acids which are characteristic of phototrophic microplankton were isotopically lighter, i.e. -17.1, -17.3 and -15.8o/oo for 20:4(n-6), 20:5(n-3) and 22:6(n-3) respectively. The non-methylene interrupted dienes (NMIDs) 20:2Delta5,13 and 22:2Delta7,15 were detected in all samples although in small amounts with R. exoculata containing the highest amounts. The (n-4) dienes and NMIDs are consistent with a substantial dietary input of bacterially derived 16:1(n-7) and 18:1(n-7) fatty acids for this species. Thus, these results are consistent with R. exoculata adopting a bacterivorous mode of nutrition whilst A. markensis is essentially a scavenger (necrophagous) and suggest that the 2 species are not in direct competition for their food supply.