脂质提取对不同海洋捕食者的同位素值（δ S、δ C 和 δ N）具有组织依赖性影响。

Lipid extraction has tissue-dependent effects on isotopic values (δ S, δ C, and δ N) from different marine predators.

机构信息

Marine Predator Research Group, School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia.

School of Environmental and Life Sciences, University of Newcastle, Ourimbah, New South Wales, Australia.

出版信息

Rapid Commun Mass Spectrom. 2022 Sep 30;36(18):e9346. doi: 10.1002/rcm.9346.

DOI:10.1002/rcm.9346

PMID:35737589

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC9539579/

Abstract

RATIONALE

The use of sulfur isotopes to study trophic ecology in marine ecosystems has increased in the past decade. Unlike other commonly used isotopes (e.g., carbon), sulfur can better discriminate benthic and pelagic productivity. However, how lipid extraction affects sulfur isotopic values has not been assessed, despite its frequent use to remove lipid effects on δ C values.

METHODS

We used white muscle and liver samples from two species of sharks and skin samples from two species of pinnipeds (sea lion and fur seal) to assess the effects of lipid extraction on stable isotope values for δ S, δ C, and δ N. Isotopic values were determined using a continuous flow-isotope ratio mass spectrometer coupled to an elemental analyzer.

RESULTS

Lipid extraction significantly decreased δ S values in shark tissues, more so for liver than muscle (-4.6 ± 0.9‰ vs -0.8 ± 0.3‰, average change), with nearly no change in their standard deviations. Lipid extraction did not affect δ S values from pinniped skin samples (0.2 ± 0.8‰, average change). After lipid extraction, consistent increases in δ C values (0.2‰-7.3‰) were detected as expected, especially in tissue with high lipid content (C:N >4). After lipid extraction, significant increases in δ N values (0.5‰-1.4‰) were found in shark muscle and liver tissues. For pinniped skin samples, δ N values were not significantly lower after lipid extraction (-0.4‰ to -0.1‰).

CONCLUSIONS

Lipid extraction did not have a strong impact on δ S values of shark muscle and pinniped skin (≤1‰). However, our results suggest it is essential to consider the effects of lipid extraction when interpreting results from δ S values of shark liver tissue, as they significantly depleted values relative to bulk tissue (~5‰). This may reflect selective removal of sulfolipids and glutathione present in higher concentrations in the liver than in muscle and skin and requires further investigation.

摘要

原理

在过去的十年中，利用硫同位素研究海洋生态系统中的营养生态已经有所增加。与其他常用同位素（例如碳）不同，硫可以更好地区分底栖和浮游生产力。然而，尽管经常使用脂质提取来消除 δ C 值上的脂质影响，但尚未评估脂质提取对硫同位素值的影响。

方法

我们使用了两种鲨鱼的白肌肉和肝脏样本以及两种鳍足类动物（海狮和海豹）的皮肤样本，以评估脂质提取对 δ S、δ C 和 δ N 稳定同位素值的影响。使用连续流动同位素比质谱仪与元素分析仪耦合来确定同位素值。

结果

脂质提取显著降低了鲨鱼组织中的 δ S 值，肝脏组织中的降低幅度大于肌肉组织（-4.6 ± 0.9‰与-0.8 ± 0.3‰，平均变化），而其标准偏差几乎没有变化。脂质提取对鳍足类动物皮肤样本的 δ S 值没有影响（0.2 ± 0.8‰，平均变化）。在进行脂质提取后，正如预期的那样，检测到 δ C 值的一致增加（0.2‰-7.3‰），尤其是在富含脂质的组织中（C：N > 4）。在进行脂质提取后，在鲨鱼肌肉和肝脏组织中发现 δ N 值显著增加（0.5‰-1.4‰）。对于鳍足类动物皮肤样本，在进行脂质提取后 δ N 值没有显著降低（-0.4‰至-0.1‰）。