国际刑警组织DNA技术的应用和数据交换

国际刑警组织为了对各成员国的DNA检验工作提供技术支持 ,促进DNA技术的广泛应用 ,设立了DNA组。DNA专家组是DNA组的主要咨询机构 ,负责推荐DNA采样和证据采集、DNA数据库、质量控制、DNA技术培训等方面的指导原则。国际刑警组织还定期召开国际DNA用户大会 ,开展地区性DNA技术培训 ,以促进DNA技术的普及、应用和发展。本文主要介绍国际刑警组织在DNA技术方面开展的工作及推荐的一些指导原则。     

DNA IQ磁珠法结合Maxwell~（TM） 16自动仪提取接触DNA

目的研究DNA IQ磁珠法结合MaxwellTM 16自动仪对接触DNA提取的应用价值。方法 151份案件接触DNA检材95℃裂解后,采用DNA IQ磁珠法结合MaxwellTM 16自动仪提取DNA,然后进行DNA定量和STR分型检测,统计各种类型的接触DNA含量I、PC CT值和STR分型成功率。结果 151份案件接触DNA检材中,除果核平均DNA获得量为9.51ng以外,其它接触检材的平均DNA获得量均大于10ng,烟蒂检验成功率最高为93%,果核检验成功率较低,为60%。所有DNA样品的IPC CT值均在27左右,纯度高。结论大部分接触DNA检材采用DNA IQ磁珠法结合MaxwellTM 16自动仪可提取到足以进行STR分型的DNA。     

中国DNA数据库建设应用技术现状及发展趋势

中国的法庭科学DNA数据库建设历经10年,在应用中取得了显著成果.随着DNA分析技术的进步,DNA数据库更加完善,DNA信息作用更加突显.本文综述了中国DNA数据库的规划与建设,DNA数据库建设中的应用技术,以及DNA数据库建设应用技术发展趋势,为完善DNA数据库建设提供借鉴.     

D17Z1探针点杂交DNA定量研究

本研究化学合成了高等灵长类特异性α卫星寡核苷酸片段(D17Z1),经辣根过氧化物酶标记、分子杂交、化学发光法检测,建立了高等灵长类特异性DNA精确定量的方法.制备了DNA浓度梯度标准对照.对人类DNA,猴、猪、牛、羊、鸡、兔、鱼、小鼠等常见动物DNA及JMl09大肠杆菌、入DNA、φ174DNA等微生物DNA进行了定量分析.结果表明,应用该方法对人类DNA定量不受非高等灵长类动物DNA与微生物DNA的影响,可实现组分定量;灵敏度测试,可对0.12ng的人类DNA进行定量,适用于法医DNA检验定量分析.     

福尔马林固定石蜡包埋组织中DNA提取

由于甲醛介导的DNA损伤和石蜡对DNA提取的阻碍作用,使得常规DNA提取方法很难从福尔马林固定石蜡包埋组织(FFPET)中获取高质量的DNA。近年来,众多学者的研究表明,通过改良预处理方法,优化蛋白酶K消化作用,简化DNA提取步骤,纯化DNA提取物等,可以有效提高FFPET中提取的DNA质量,为FFPET的DNA分析奠定了基础。     

法医DNA实验室的DNA污染和防范

DNA污染是产生DNA鉴定结论错误的重要因素,法医DNA实验室要努力去解决这一问题。DNA污染有自身污染、交叉污染、PCR污染3种。法医DNA实验室要采取实验室分区、严格检验操作步骤、对试剂及消耗材料进行质量控制等方法防止发生DNA污染,采取设置对照样本、核查DNA结果、建立DNA排查数据库等方法监测和发现DNA污染。     

浅谈DNA信息的正确解读与合理利用

20世纪80年代中期DNA分析技术被应用于法庭科学领域后,DNA技术在法庭科学实践中发挥了重要作用.但随着DNA技术的发展和运用,我们也发现人们对DNA证据价值的认识在某些方面尚存在误区.片面夸大DNA证据价值,对DNA信息不能正确解读与合理运用,导致在案件侦查中走弯路,甚至发生冤假错案.根据法医DNA分析的原理,本文对如何正确解读与合理利用DNA信息进行了探讨.     

论DNA鉴定结论的证据效力研究

DNA分析技术发展迅速,具有很多其它法庭科学技术不可比拟的优点,广泛用于刑事案件侦查、民事纠纷解决等。虽然我国DNA鉴定技术上与国际水平差距不大,但因为缺乏相应证据规则,DNA鉴定结论在应用上表现出诸多问题。为了规范DNA鉴定结论的应用,本文从DNA鉴定使用的遗传标记衡量DNA鉴定结论的证明力大小,从鉴定机构是否合法、受案程序是否得当、DNA鉴定过程是否符合17025标准等方面判断DNA鉴定结论是否具有证明效力。在认定DNA鉴定结论有证明效力的前提下判断其证明力大小,即判断能否达到个体识别和亲权鉴定的目的。此外,呼吁我国尽早出台DNA证据规则,以规范DNA鉴定结论的应用。     

DNA芯片与法医生物物证检验

DNA芯片是把许许多多已知的某种或某类 DNA片段 ( 作为分子探针 ) 以阵列形式有序地点加在某种基质或载体上 , 形成分子探针的集群或矩阵 , 其中每个探针的位置是固定可寻的 , 犹如计算机的芯片一样 . 将被检测物质与芯片进行杂交 , 若其中含有与芯片中阵列 DNA序列相配对的 DNA片段时 , 通过检测手段把这些配对物检测出来 , 分析计算配对物的相对比率 , 就可以对被检物质做出检验或鉴定结论 . DNA芯片又称为 DNA微矩阵 (DNA microarray[1])或基因芯片 (Gene chips), 但作者认为不宜把 DNA芯片与基因芯片等同起来 , 因为基因芯片应是针对可表达的 DNA片段即外显子的 , 而 DNA芯片则是包括了可表达与不能表达的 DNA片段的全部 , 后面要提到的法医物证检验所用 DNA芯片使用的就是不能表达的 DNA片段即内含子 .     

法庭DNA技术的发展及展望

1 法庭DNA技术的现状 DNA技术自1985年应用于法庭鉴定以来,发展极为迅速,得到了广泛应用。已经由最初的以长度(RFLP)为基础的DNA指纹分型技术(DNA Fingerprinting)发展到如今的扩增片段长度多态性检测(PCR-VNTR,PCR-STR)及DNA序列变异测定等。其中应用比较普遍的几项法庭DNA鉴定技术分别为DNA指纹图技术、PCR扩增技术、DNA测序技术。     

Busting the myths: DNA typeability after 48 hours of boil

The aim of our study was to monitor the quality and quantity of DNA in bone samples that were boiled for 48 h. Bos taurus bone disks were sampled every hour for 48 h. The subsequent DNA analysis used multiple mitochondrial DNA (mtDNA) targets (100–700 bp) to evaluate the quality and quantity of the DNA extracted. The DNA extracted from bone disks remained typeable after boiling for 48 h. We have proven that DNA typing results can be obtained even after long-term boiling.     

Efficiency of Casework Direct Kit for extraction of touch DNA samples obtained from cars steering wheels

Analysis of STR profiles obtained from touch DNA has been very useful to the elucidation of crimes. Extraction method may be determinant for the recovery of genetic material collected from different surfaces. Vehicle theft is one of the most common crimes in São Paulo city, Brazil, but collection of biological traces in car steering wheels is not considered, because of the belief that profiles generated won’t be able to identify the thief, only the owner. This study aimed to analyze the efficacy of extraction methods for obtaining DNA profiles in samples collected from steering wheels. Eight criminal acts were simulated with 2 different individuals each (mixture of victim and thief), in duplicate, in order to compare two extraction methods: DNA IQ™ and Casework Direct Kit (both Promega Corporation). Genetic material was collected by double swab method and quantified by Quantifiler™Trio (ThermoFisher Scientific). Amplification was conducted with PowerPlex® Fusion System (Promega). It was possible to obtain STR profiles for all experiments. The mixtures were compared with reference profiles to evaluated how many alleles of each donor were observed. Samples extracted with Casework Direct Kit obtained STR profiles with higher averages of alleles for primary and secondary donors (88.7% and 59.9%, respectively) than those extracted with DNA IQ™ (60.4% and 38.1%, respectively). This could be explained by the differences established in the protocols of both methods, since DNA IQ™ is based on successive washes and can result in loss of DNA, whereas Casework Direct Kit minimizes this problem. We concluded that Casework Direct Kit was more efficient for processing touch DNA samples than DNA IQ™.     

DNA Purification Cell Lysis and Wash Step Modifications for Low-Template DNA Sample Processing,

As DNA technology becomes increasingly sensitive, forensic laboratories are receiving more low-template DNA samples. These samples, already low in DNA content, become even more challenging to process as the available DNA becomes further reduced during the extraction step. In this study, two extraction modifications were tested to determine if the cause of DNA loss could be identified and mitigated. A double lysis technique was used to test for DNA loss in the sample collection substrate, and lysate eluates were re-extracted to determine DNA loss from inefficient binding to the silica column. Both modifications showed DNA was lost at these steps. However, resulting STR profiles from these samples had fewer peaks and lower peak heights when compared to samples processed with no extraction modifications. Overall, the potential benefits of adding these extraction modifications for low-template DNA sample processing are not enough to justify the risk associated with additional manipulation.     

Genetic identification of biological samples buried in clay soil during summer and winter seasons

The analysis of a biological samples found in crime scenes can be a challenging task. Minute amount of DNA, degraded DNA and the presence of inhibitors in biological samples, can interfere with the achievement of a complete genetic profile.Chelating resin, silica membranes and silica-coated with paramagnetic resin were the techniques used in this study for the isolation and purification of DNA. Our aim was to find out the best DNA extraction method for application in the presence of biological samples buried in clay soil.     

Chelex法和两种磁珠法提取接触DNA效果的比较

目的比较Chelex法、DNA IQ磁珠法、EQ国产磁珠法对接触DNA的提取效果。方法将稀释为10ng、100ng的标准品DNA,分别采用Chelex法、DNA IQ磁珠法、EQ国产磁珠法处理;对30例烟蒂和30例牙刷分别采用Chelex法、DNA IQ磁珠法和EQ国产磁珠法提取DNA,然后进行PCR定量和STR检测。结果Chelex法对DNA的提取无损失,DNA IQ磁珠法、EQ国产磁珠法对DNA的提取均有不同程度的损失;烟蒂、牙刷等检材采用Chelex法提取的接触DNA量和IPC CT值显著高于IQ磁珠法、EQ国产磁珠法,但STR检验成功率却低于IQ磁珠法、EQ国产磁珠法。2种磁珠法提取的DNA量、IPC CT值和STR检验成功率无显著性差异。结论污染轻、杂质少的接触DNA检材,用Chelex法提取最为方便快捷;IQ磁珠法、EQ国产磁珠法更适合污染接触DNA检材的提取及自动化操作。     

Validation of the InnoXtract™ DNA extraction method for bone,teeth, and rootless hair

Forensic casework samples often include human hairs, teeth, and bones. Hairs with roots are routinely processed for DNA analysis, while rootless hairs are either not tested or processed using mitochondrial DNA. Bones and teeth are submitted for human remains identifications for missing persons and mass disaster cases. DNA extraction from these low templates and degraded samples is challenging. The new InnoXtract DNA extraction method utilizes magnetic beads that are optimized to bind small DNA fragments, as small as 100 base pairs, to purify high-yield DNA from compromised samples. This validation study evaluates InnoXtract's ability to obtain amplifiable DNA from samples such as rootless hairs and skeletal remains. Studies performed include sensitivity, stability, repeatability, reproducibility, non-probative samples, and comparison to standard organic extractions. Sensitivity studies demonstrate average yield recoveries ranging from 53% to 100% and 73% to 85% for the InnoXtract hair and bone methods, respectively. Studies demonstrate consistent results across a range of sample types, such as insulted and un-insulted bone and teeth, as well as hair shafts from donors of various ages, gender, race, and hair characteristics. The InnoXtract bone method outperformed organic extraction. The method was successfully automated on a MagMAX™ Express-96, with recoveries over 70% relative to the manual version. InnoXtract has the potential as an automated high-throughput, high-yield bone extraction method with 6 h of total extraction time for up to 96 samples. The validation study results demonstrate that the InnoXtract kits produce high-yield and high-quality DNA from compromised bone, teeth, and hair shaft samples.     

The effect of NucleoSpin® Forensic Filters on DNA recovery from trace DNA swabs

Forensic DNA profiling is a globally accepted method for human identification, however, obtaining full DNA profiles from trace DNA can be challenging. The optimal recovery of DNA from trace DNA swabs is therefore crucial. Methods for extracting DNA from swabs often make use of a spin basket combined with a centrifugation step, to enhance the release of cells from the swab prior to DNA extraction. The NucleoSpin® Forensic Filter (Macherey-Nagel, Düren) is a type of spin basket, but it has not been thoroughly assessed on trace DNA samples. This study aimed to assess if the inclusion of the NucleoSpin® Forensic Filter significantly improved DNA recovery and DNA profiling success from cotton and flocked swabs used to collect trace DNA and buccal cells (control). Buccal cells and trace DNA samples were collected from 25 volunteers using each swab type (cotton and flocked) in duplicate. DNA was extracted from the samples using the NucleoSpin® DNA Forensic kit, one set with, and the other set without, NucleoSpin® Forensic Filters. DNA concentration was assessed using real time PCR, and DNA profiling was done using the PowerPlex® ESX 16 system. The inclusion of the NucleoSpin® Forensic Filters significantly improved DNA concentration for buccal cells that were collected using flocked swabs (p = 0.035). However, no significant differences were noted for trace DNA samples for either swab type. There was also no significant difference in DNA profiling success when NucleoSpin® Forensic Filters were used, regardless of swab and sample type. These results may be helpful for laboratories that are considering the NucleoSpin® Forensic Filters in the DNA extraction workflow, particularly for trace DNA samples.     

Assessing DNA recovery and profile determination from bloody snow

Successful DNA typing of forensically relevant evidence is reliant on both the quality and quantity of biological material recovered from a crime scene. In geographical areas of the world exposed to cold climates, it is not uncommon for biological evidence to encounter a diversity of challenging surfaces and environments, including snowy surfaces. Currently, there is no standard protocol for recovery of bloodstain evidence in snow and very few publications exploring adequate methods of recovering biological evidence from snowy surfaces. In this study, three common substrates (e.g., cotton swabs, FTA paper, and untreated filter paper) utilized by investigators for evidence recovery were evaluated for their ability to recover human blood (DNA) evidence from snow that would be viable for traditional forensic DNA typing. Each biological sample was extracted and quantified to evaluate the quality and quantity of DNA recovered. All samples yielded sufficient non-degraded DNA to proceed with DNA profiling, where complete DNA profiles were generated from each collection substrate. The experimental findings presented herein demonstrate that the ability to recover viable DNA from human blood collected on surface snow is possible using all three collection methods tested.     

STRAND: A Cloud expert system for non-human DNA analysis

The aim of this paper is to present the STRAND (STR ANimal Database) cloud expert system for non-human DNA analysis. The cloud expert system (CES) combines the cross-referenced registries of STR markers for different species and a DNA database for comparison of DNA profiles, with a repository of scientific papers and a dashboard for unpublished data, protocols, negative results and announcements related to animal DNA typing.