Forensic samples with low DNA template amounts are difficult to analyze and interpret. There is a large body of research demonstrating that adding carrier nucleic acid to storage tubes, solid phase extractions, or filtering devices can improve yields of target DNA. However, the addition of carrier nucleic acid to sampling substrates, like cotton swabs, has not yet been attempted. In this proof-of-concept study, carrier nucleic acids in the form of either Poly (A) RNA or salmon sperm DNA were spotted onto cotton swabs, followed by human genomic DNA, to determine if introducing the carrier prior to sample collection would increase recovery from the swabs post-extraction. Extracts were also evaluated to determine whether adding the carrier nucleic acids to human DNA would interfere with downstream forensic DNA analysis processes such as real-time PCR quantitation, PCR amplification of STR loci, or capillary electrophoresis. The RNA carrier did not improve human sample recovery from cotton swabs. The extraction efficiency of human DNA from cotton swabs was increased when the DNA carrier was applied to the swabs prior to sample deposition, and the scale of the increase depended on the amount of carrier DNA used. When applying the salmon sperm DNA carrier to cotton swabs, with each increase from no carrier to 0.001–1–10 µg, human DNA recovery went from ∼29 % to ∼50 % to ∼75 % to ∼100 %. Additionally, no inhibitory effects from the carrier DNA were observed post-extraction with quantitation or in the DNA profile after amplification. Therefore, salmon sperm DNA carrier will increase human DNA yield from cotton swabs without negative effects on downstream forensic DNA profiling methods, with the optimal carrier amount being 10 µg.

DNA 模板量低的法医样本难以分析和解释。大量研究表明，将载体核酸添加到储存管、固相萃取或过滤装置中可以提高目标 DNA 的产量。然而，尚未尝试将载体核酸添加到采样基质（例如棉签）中。在这项概念验证研究中，将 Poly (A) RNA 或鲑鱼精子 DNA 形式的载体核酸点样到棉签上，然后点样人类基因组 DNA，以确定在样本采集之前引入载体是否会增加提取后从拭子中恢复。还对提取物进行了评估，以确定将载体核酸添加到人类 DNA 中是否会干扰下游法医 DNA 分析过程，例如实时 PCR 定量、 STR位点的 PCR 扩增或毛细管电泳。RNA 载体并没有提高棉签中人体样本的回收率。当在样品沉积之前将 DNA 载体应用于棉签时，从棉签中提取人类 DNA 的效率会提高，并且提高的程度取决于所使用的载体 DNA 的量。当将鲑鱼精子 DNA 载体应用于棉签时，每次从无载体增加到 0.001–1–10 µg，人类 DNA 回收率从~29% 到~50% 到~75% 到~100%。此外，在定量提取后或扩增后的 DNA 谱中未观察到载体 DNA 的抑制作用。因此，鲑鱼精子 DNA 载体将提高棉签中人类 DNA 的产量，而不会对下游法医DNA 分析方法产生负面影响，最佳载体量为 10 µg。