Yao Wang, Mei Chen, Nan Xiao, Hui Liu
College of Medical Laboratory, Dalian Medical University, Dalian 116044, China; Wuxi Maternal and Child Health Hospital Affiliated Nanjing Medical University, 214002 Wuxi, Jiangsu, China.
Dalian Blood Centre, Dalian, China.
Gene. 2016 Sep 15;590(1):142-8. doi: 10.1016/j.gene.2016.06.033. Epub 2016 Jun 16.
Cell-free DNA is naturally degraded in various bodily fluids. The aim of this study was to determine the degradation kinetics of DNA, with and without protein, in serum, urine and saliva.
Naked DNA and DNA-protein complex were prepared, added to the samples to be analysed and incubated at 37°C and room temperature for various lengths of time. Alleles of 20 short tandem repeat loci were amplified from the incubated samples, and clearance models were generated from the mean peak areas.
Plotting the natural logarithm of DNA concentration against the incubation time produced a linear relationship. The half-lives of DNA with and without protein in serum were 157.6min and 30.8min at 37°C, 330.5min and 70.5min at room temperature, respectively. The half-lives of DNA with protein in saliva were 175.6min and 251.3min at 37°C and room temperature, respectively. However, the half-lives of DNA in urine (both with and without protein) were too short to detect.
The kinetics of DNA degradation in serum and saliva followed a first-order clearance model. Urine had the strongest effect on DNA degradation, and the half-lives of DNA with protein were relatively longer than those of naked DNA.
游离DNA在各种体液中会自然降解。本研究的目的是确定血清、尿液和唾液中有无蛋白质情况下DNA的降解动力学。
制备裸DNA和DNA-蛋白质复合物，加入待分析样本中，并在37°C和室温下孵育不同时长。从孵育后的样本中扩增20个短串联重复序列位点的等位基因，并根据平均峰面积生成清除模型。
将DNA浓度的自然对数与孵育时间作图呈现线性关系。血清中含蛋白质和不含蛋白质的DNA在37°C时的半衰期分别为157.6分钟和30.8分钟，在室温下分别为330.5分钟和70.5分钟。唾液中含蛋白质的DNA在37°C和室温下的半衰期分别为175.6分钟和251.3分钟。然而，尿液中DNA（含蛋白质和不含蛋白质）的半衰期太短无法检测。
血清和唾液中DNA的降解动力学遵循一级清除模型。尿液对DNA降解的影响最强，含蛋白质的DNA半衰期相对长于裸DNA。
