Nowadays, molecular analyses play an important role in studies of soil dwelling animals, for example in taxonomy, phylogeography or food web analyses. The quality of the DNA, used for later molecular analyses, is an important factor and depends on collection and preservation of samples prior to DNA extraction. Ideally, DNA samples are frozen immediately upon collection, but if samples are collected in the field, suitable preservation methods might be limited due to unavailability of resources or remote field sites. Moreover, shipping samples over long distances can cause loss of DNA quality e.g. by thawing or leaking of preservation liquid. In this study we use earthworms, a key organism in soil research, to compare three different DNA preservation methods – freezing at −20 °C, storing in 75% ethanol, and freeze drying. Samples were shipped from the United States of America to Austria. The DNA of the samples was extracted using two different extraction methods, peqGOLD™ and Chelex® 100. The DNA amplification success was determined by amplifying four DNA fragments of different length. The PCR amplification success is significantly influenced by preservation method and extraction method and differed significantly depending on the length of the DNA fragment. Freeze drying samples was the best preservation method when samples were extracted using the silica based extraction method peqGOLD™. For samples that were extracted with Chelex® 100, storage in ethanol was the best preservation method. However, the overall amplification success was significantly lower for the extraction procedure based on Chelex® 100. The detection of the small DNA fragments was higher and independent from the extraction method, while the amplification success was significantly reduced for the longer DNA fragments. We recommend freeze drying of DNA samples, especially when they have to be shipped for longer distances. No special packaging or declaration is needed for freeze dried samples, and the risk of thawing is excluded. Storage of freeze dried samples also reduces costs because samples can be kept at room temperature in a desiccator. It should be noted, that the extraction methods showed significant differences in DNA amplification success. Thus, the extraction method should be taken into account when choosing the preservation method.

中文翻译：

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用于 DNA 分析的组织样本的储存和运输：蚯蚓案例研究

如今，分子分析在土壤栖息动物的研究中发挥着重要作用，例如在分类学、系统地理学或食物网分析中。用于后续分子分析的 DNA 质量是一个重要因素，取决于 DNA 提取前样本的收集和保存情况。理想情况下，DNA 样本在收集后立即冷冻，但如果样本是在现场收集的，由于资源或远程现场站点的不可用，合适的保存方法可能会受到限制。此外，长距离运输样品会导致 DNA 质量下降，例如保存液解冻或泄漏。在这项研究中，我们使用土壤研究中的关键生物蚯蚓来比较三种不同的 DNA 保存方法——-20 °C 冷冻、75% 乙醇储存和冷冻干燥。样品从美国运往奥地利。使用两种不同的提取方法 peqGOLD™ 和 Chelex® 100 提取样品的 DNA。通过扩增四个不同长度的 DNA 片段来确定 DNA 扩增的成功。PCR扩增成功受保存方法和提取方法的显着影响，并因DNA片段的长度而异。当使用基于二氧化硅的提取方法 peqGOLD™ 提取样品时，冷冻干燥样品是最好的保存方法。对于用 Chelex® 100 提取的样品，在乙醇中储存是最好的保存方法。然而，基于 Chelex® 100 的提取程序的总体扩增成功率明显较低。小 DNA 片段的检测率较高且与提取方法无关，而较长 DNA 片段的扩增成功率显着降低。我们建议对 DNA 样品进行冷冻干燥，尤其是在必须运输较长距离时。冻干样品无需特殊包装或声明，排除解冻风险。冷冻干燥样品的储存也降低了成本，因为样品可以在干燥器中保持室温。应该指出的是，提取方法在 DNA 扩增成功率方面表现出显着差异。因此，在选择保存方法时应考虑提取方法。我们建议对 DNA 样品进行冷冻干燥，尤其是在必须运输较长距离时。冻干样品无需特殊包装或声明，排除解冻风险。冷冻干燥样品的储存也降低了成本，因为样品可以在干燥器中保持室温。应该指出的是，提取方法在 DNA 扩增成功率方面表现出显着差异。因此，在选择保存方法时应考虑提取方法。我们建议对 DNA 样品进行冷冻干燥，尤其是在必须运输较长距离时。冻干样品无需特殊包装或声明，排除解冻风险。冷冻干燥样品的储存也降低了成本，因为样品可以在干燥器中保持室温。应该指出的是，提取方法在 DNA 扩增成功率方面表现出显着差异。因此，在选择保存方法时应考虑提取方法。应该指出的是，提取方法在 DNA 扩增成功率方面表现出显着差异。因此，在选择保存方法时应考虑提取方法。应该指出的是，提取方法在 DNA 扩增成功率方面表现出显着差异。因此，在选择保存方法时应考虑提取方法。