Highly efficient and automated extraction of DNA from human remains using a modified EZ1 protocol

Bones and teeth often represent the only sources of DNA available for identifying human remains. DNA in bones and teeth is generally better preserved than that in soft tissues because of the presence of hard connective tissue with a high level of calcium. Because of the extensive mineralisation, the choice of an efficient DNA extraction procedure is important to minimise the sampling of a high level of minerals and to remove polymerase chain reaction (PCR) inhibitors. Some protocols are available for DNA extraction from bones and teeth as part of the Qiagen EZ1 DNA Investigator Kit using the EZ1 Advanced XL automated purification platform. To improve the efficiency of DNA extraction from skeletal remains, the present study focuses on a modification to these already available protocols. In this study, different bones and teeth collected between 1 and 50 years after death were subjected to DNA extraction using the standard EZ1 protocol, a supplementary protocol, and a modified protocol. The modified approach included a decalcification step, whereas the Qiagen protocols worked directly on non-decalcified powder. In all three procedures, 150 mg samples were used for DNA extraction. We evaluated the quantity of DNA recovered from samples, the presence of any PCR inhibitors co-extracted, the level of DNA degradation, the quality of short tandem repeat (STR) profiles, and the reproducibility of the modified procedure. When compared with the other protocols, the modified protocol resulted in the best recovery of DNA that was free of PCR inhibitors. Additionally, the STR profiles were reliable and of high quality. In our opinion, the decalcification step increases DNA recovery by softening tissues, which allows lysis solutions to act more effectively. Furthermore, the use of two lysis solutions and the variation added to the EZ1 purification step allow for DNA recovery with quality and quantity superior to those of the previously available Qiagen-based protocols. These findings may be helpful solutions to the problems commonly encountered when dealing with difficult samples, such as bones and teeth.

Key points

• Bones and teeth often represent the only sources of DNA for identifying human remains.
• The choice of an efficient DNA extraction procedure is important for maximizing DNA recovery and removing PCR inhibitors.
• This study focuses on modifications to the previously available Qiagen-based protocols.
• The modified protocol enabled the best recovery of DNA, and both quality and quantity were superior to those of the previously available Qiagen-based protocols.
• The STR profiles obtained from samples extracted using the modified protocol were reliable and of high quality.

     

Striation Density for Predicting the Identifiability of Fired Bullets with Automated Inspection Systems*

Abstract: Automated firearms identification systems will correlate a reference bullet with all evidence bullets without a selection procedure to exclude the bullets having insufficient bullet identifying signature. Correlations that include such bullets increase the workload and may affect the correlation accuracy. In this article, a parameter called striation density is proposed for determining and predicting bullet identifiability. After image preprocessing, edge detection and filtering techniques are used to extract the edges of striation marks, the resulting binary image distinctly shows the amount and distribution of striation marks. Then striation density is calculated for determining the quality of images. In the experiment, striation densities for six lands of 48 bullets fired from 12 gun barrels of six manufactures are calculated. Statistical results show strong relation between striation density and identification rate. It can provide firearms identification systems with a quantitative criterion to assess whether there are sufficient striae for reliable bullet identification.     

基于X线的活体骨骼年龄评定方法及其他技术

国内外通常利用X线片观察骨骼继发性骨化中心的出现和骨骺闭合程度的影像学特征来推断年龄。其中较常用的方法有计数法、计测法、图谱法、评分法及计算机辅助评定骨龄法等。目前国外普遍采用TW评分法。国内也有该评分法的应用报道。主要应用于体育和儿科临床实践中。法医临床学实践中常用六大关节判别方程法推断骨龄和活体年龄推断。其他还有利用牙齿内天冬氨酸的消旋化、骨密度检测以及端粒末端DNA片段长度的变化等年龄推断方法。     

采矿权并非用益物权的法理辩析——与中国政法大学李显冬教授商榷

《物权法》颁布，一贯主张采矿权属准物权的专家转向采矿权属最完整的用益物权，以矿产资源是劳动对象，开采中即时消耗不须返还为采矿权客体的被处分作辩解。但是，法律关系的客体和经济关系的劳动对象不可能相通，而且客体没有在开采中即时消耗，完全可以速还，客体被处分误为标的物被消耗。采矿权是财产权、行政权、行为权三个不同层面整合的多面体，不同层面的性质不同。应重构采矿权为独立的矿产权和采掘权（开采权），矿产权是国有特定矿产所有权的让渡，属自物权。     

关于中俄矿产资源合作的思考

俄罗斯丰富的矿产资源和我国巨大的市场将使两国在长期稳定的合作中互利双赢。中俄两国加强矿产资源合作,不仅有助于解决我国国内矿产资源供应的瓶颈问题,同时也是推动两国战略协作伙伴关系和经贸合作升级的关键突破口之一。     

X线片的骨骼年龄判定

目前,对儿童青少年骨骼年龄评价以手腕部及膝部较好,方法也较多,但主观性强,随机误差大。随着计算机图像识别及智能化技术的应用,将使得骨骼年龄评价更为客观、准确。对于成年人X线片骨龄推断,以胸骨、耻骨及锁骨等方法具有一定的应用价值,尚需更广泛的方法学研究以增加推断年龄的方法及准确性。本文介绍了X线片的骨骼年龄判定方法的现状及研究进展。     

浅谈非法采矿罪与破坏性采矿罪的区分

非法采矿罪和破坏性采矿罪的区分关键在于,前罪具有前提的违法性,而后罪则具有前提的合法性,两罪对于破坏性采矿方法的要求是一致的。     

日粮中维生素D3含量对笼养蛋鸡骨矿含量及骨显微结构的影响

将 175只 10周龄伊莎蛋鸡随机分为A、B、C、D、E共 5组 ,分别在每千克饲料中添加维生素D3(VD3) 0、10 0、2 0 0、5 0 0和 10 0 0IU ,试验期 10周。试验期间每隔 2周测定骨矿含量。试验开始及结束时杀鸡取胫骨 ,进行组织学检查。试验结束时 ,A、B、C、D、E组骨矿总平均值分别为0 .6 6 8g/cm2 ± 0 .0 82g/cm2 、0 .6 79g/cm2 ± 0 .10 2g/cm2 、0 .6 92g/cm2 ± 0 .10 3g/cm2 和 0 .6 6 8g/cm2 ± 0 .0 81g/cm2 、0 .6 47g/cm2 ± 0 .0 79g/cm2 。C组骨矿含量显著高于A、D、E组 (P <0 .0 5 )。骨组织学检查亦显示 ,试验开始时 ,青年蛋鸡皮质骨、骨小梁正常 ;试验结束时 ,低VD3组和高VD3组皮质骨都出现了不同程度吸收腔增多的现象 ,且严重程度与VD3缺乏或过量程度呈正相关性。试验结果表明 ,青年蛋鸡日粮中添加适宜剂量的VD3,可增加骨量 ,维持良好的骨结构。     

Microscopic Residues of Bone from Dissolving Human Remains in Acids

Dissolving bodies is a current method of disposing of human remains and has been practiced throughout the years. During the last decade in the Netherlands, two cases have emerged in which human remains were treated with acid. In the first case, the remains of a cremated body were treated with hydrofluoric acid. In the second case, two complete bodies were dissolved in a mixture of hydrochloric and sulfuric acid. In both cases, a great variety of evidence was collected at the scene of crime, part of which was embedded in resin, polished, and investigated using SEM/EDX. Apart from macroscopic findings like residual bone and artificial teeth, in both cases, distinct microscopic residues of bone were found as follows: (partly) digested bone, thin‐walled structures, and recrystallized calcium phosphate. Although some may believe it is possible to dissolve a body in acid completely, at least some of these microscopic residues will always be found.     

Raman Spectroscopic Differences between Ephedrine and Pseudoephedrine

Ephedrine (EPH) and pseudoephedrine (PSE) were studied by micro‐Raman spectroscopy and UV resonance Raman spectroscopy excited at 785 and 360 nm, respectively. Raman bands at approximately 245 and 410 cm^?1 for ephedrine have apparent differences from the same bands at approximately 215, 265, 350, 450, and 555 cm^?1 for pseudoephedrine, and these differences can be applied to distinguish between EPH and PSE. Additionally, density functional theory was used for the Raman calculations to obtain results identical to the experimental spectra. This work is expected to expand the applications of Raman spectroscopy in forensic science.