Carbon and nitrogen stable isotope and molecular analyses are common tools for marine ecological and biological research. However, it is difficult to fix samples for both analyses using only one preservative. A solution of potassium iodide and iodine (known as Lugol's iodine solution) is considered to be a suitable preservative; however, the effectiveness of Lugol's iodine solution for long‐term preservation of samples for stable isotope analysis and molecular analysis has not yet been investigated. We tested the effectiveness of 5% and 10% Lugol's iodine solutions by comparing them with marine plankton samples preserved in a 5% formalin solution, as well as preserved by freezing. Although δ¹³C and δ¹⁵N values of samples fixed in 5% formalin and 5% Lugol's iodine solution were significantly different from those of frozen samples, there were no significant differences in both δ¹³C and δ¹⁵N values between samples fixed in 10% Lugol's iodine solution and frozen samples, when preserved for a duration from 1 week up to 6 months. Polymerase chain reaction (PCR) assay of samples fixed in 10% Lugol's iodine solution after 18 months of preservation succeeded; however, the DNA in samples fixed in 5% formalin and 5% Lugol's iodine solution could not be amplified using PCR. There was no difference in the sequences of partial 18S rRNA genes between samples fixed in 10% Lugol's solution and frozen samples. Thus, we conclude that 10% Lugol's solution is a suitable fixative for both of carbon and nitrogen stable isotope and molecular analyses.

中文翻译：

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卢戈尔碘对海洋浮游生物样品长期保存的影响，以进行分子和稳定的碳氮同位素分析

碳氮稳定同位素和分子分析是海洋生态和生物学研究的常用工具。但是，仅使用一种防腐剂很难固定两种分析的样品。碘化钾和碘的溶液（称为Lugol碘溶液）被认为是合适的防腐剂。然而，尚未研究过Lugol碘溶液对样品进行长期保存以进行稳定同位素分析和分子分析的有效性。通过将它们与5％福尔马林溶液中保存的以及冷冻保存的海洋浮游生物样品进行比较，我们测试了5％和10％的Lugol碘溶液的有效性。虽然δ ¹³ C和δ ¹⁵固定在5％福尔马林和5％复方碘碘溶液样本的N个值是来自那些冷冻样品的显著不同，有在两个δ无显著差异¹³ C和δ ¹⁵当保存1周至6个月时，固定在10％的Lugol碘溶液中的样品与冷冻样品之间的N值。保存18个月后，用10％Lugol碘溶液固定的样品的聚合酶链反应（PCR）分析成功；但是，用PCR无法扩增固定在5％福尔马林和5％Lugol's碘溶液中的样品中的DNA。在10％Lugol溶液中固定的样品和冷冻样品之间的18S rRNA部分基因序列没有差异。因此，我们得出的结论是，对于碳和氮稳定同位素和分子分析，10％的卢戈尔溶液都是合适的固定剂。