三种提取前处理方法对金属检材DNA分型的影响

Effects of Three Pre-extraction Treatments on STR Profiling of the DNA Obtained from Size-small Metal Articles

目的探索一种适合于提取小尺寸金属检材上DNA的前处理方法。方法选择M4型螺丝钉作为本研究的对象,经消毒去污处理,通过手握方式使人体脱落细胞覆盖于其表面,DNA提取前对螺丝钉分别采用三种不同的前处理方法(方法 1:直接浸泡载体;方法 2:震荡洗涤载体;方法 3:二步擦拭载体),对经提取并纯化的样本采用Amicon Ultra-0.5超滤膜浓缩。结果方法 2获得的STR分型谱带均一、平衡性好,等位基因峰值面积和检出率均显著高于方法 1和方法 3提取组;方法 3提取组整体峰值面积较低,大部分测试样本STR分型存在等位基因丢失和非特异性扩增现象;方法 1提取组中的样本基本未获得有效的STR分型谱带。结论对尺寸较小、形状不规则的金属检材,如螺丝钉帽、铜丝铁线、铁珠铁片等,可采用方法 2进行前处理,富集其上脱落细胞而后进行DNA提取,获得的DNA分型结果较为理想,方法 1对检材DNA的提取前处理方式不宜采用。

Objective To explore a pre-extraction treatment suitable for DNA recovery from size-small metal articles.Methods Screws(size of M4),the tested samples of this research,were previously decontaminated and disinfected so asto make them covered with the exfoliated cells adhering onto their surfaces by hand holding,and then subjected to conductthree kinds of pre-extraction treatment(1:direct immersion of the screws into lysis solution;2:oscillation to wash the screwsin lysis solution;3:two-step wiping of the screws via swabs)before DNA extraction.The collected and purified DNA wasconcentrated with Amicon Ultra-0.5.Results With the second kind of treatment,the STR typing revealed the DNA bandsare of almost homogeneous and balanced,comparatively much better than the results obtained with the other two choices oftreatment because of the two compared showing smaller areas of STR electrophoretic peaks and significant occurrence ofallelic loss plus some non-specific amplifications.Even worse,the treatment of direct immersion of the screws just showedcompletely negative results because all the STR typing DNA bands were under the threshold set for this test.Conclusion Inorder to obtain the ideal STR profiling from size-small and shape-irregular metal articles(the DNA carriers),the second preextractiontreatment,i.e.,oscillation to wash the screws in this test,is suitable but the direct immersion way should absolutelynot be suggested.