Harris County Institute of Forensic Sciences, Houston, TX, United States.
School of Forensic Sciences, Oklahoma State University Center for Health Sciences Tulsa, OK, United States.
Forensic Sci Int Genet. 2021 Mar;51:102456. doi: 10.1016/j.fsigen.2020.102456. Epub 2020 Dec 28.
The relationship between RNA degradation and the age of a bloodstain has been suggested by the work of several investigators. A prior study from this laboratory described a qPCR assay that was effective at estimating the age of bloodstains stored in an environmentally controlled laboratory for periods of up to one year. In this study, the effect of the environmental conditions on the rate of RNA degradation during storage was analyzed. Bloodstains were prepared on stain cards and stored in one of 9 different environments for periods of up to 24 weeks. At selected times during the storage term, RNA was extracted, reverse transcribed, and the integrity of select transcripts analyzed. Three temperatures (37 °C, 20 °C, and 4 °C) and three relative humidities (rH) (75 %, 35 %, and 10 %) were combined pairwise. The rate of RNA degradation was found to increase 5-10 fold in stains stored at 37 °C versus those stored at 20 °C. The rate of RNA degradation was faster for stains stored at 20 °C compared to 4 °C but differed only 2-4 fold. Multivariate regression analysis suggests elevations in temperature or rH will accelerate RNA degradation and will do so to a similar extent. It is clear from the data that the integrity of the transcriptome in dried bloodstains is better preserved in a cold and dry environment. Investigations are ongoing to develop an approach for the estimation of sample age that incorporates the environmental conditions of a crime scene into the age estimate.
已有研究表明，RNA 降解与血斑年龄之间存在一定关系。本实验室之前的一项研究描述了一种 qPCR 检测方法，该方法能够有效估计在环境受控实验室中储存长达一年的血斑年龄。在本研究中，分析了储存过程中环境条件对 RNA 降解速率的影响。将血斑制备在斑卡上，并储存在 9 种不同环境中，最长达 24 周。在储存期的选定时间点，提取 RNA 进行逆转录，并分析选定转录本的完整性。选择了三个温度（37°C、20°C 和 4°C）和三个相对湿度（rH）（75%、35%和 10%）进行两两组合。结果发现，与储存在 20°C 的血斑相比，储存在 37°C 的血斑中的 RNA 降解速度加快了 5-10 倍。与 4°C 相比，20°C 储存的血斑中的 RNA 降解速度更快，但仅相差 2-4 倍。多元回归分析表明，温度或 rH 的升高将加速 RNA 降解，而且其加速程度相似。从数据中可以清楚地看出，在寒冷干燥的环境中，干燥血斑中转录组的完整性得到更好的保存。目前正在进行研究，以开发一种方法来估计样本年龄，将犯罪现场的环境条件纳入年龄估计中。
