从聚丙烯酰凝胶中回收DNA片段直接PCR的简易方法

将聚丙烯酰胺凝胶中ＤＮＡＳ片段于ＰＣＲ缓冲液中洗脱，加入ＰＣＲ反应试剂直接扩增目的ＤＮＡ作进一步分析，ＤＮＡ片段回收效率为０．８９±０．０５，本方法简便、快速。     

降解DNA的PCR分型-电洗脱回收大片断DNA法

本文分析了降解ＤＮＡ作ＰＣＲ分型易失败的原因，提出了因小片断ＤＮＡ过多，阻碍引物与膜机的复性及阻断引物延伸的新现点。将降解的ＤＮＡ电泳，切除小片断ＤＮＡ，电洗脱回收较大片断ＤＮＡ，成功地对降解ＤＮＡ进行了ＰＣＲ分型．本方法简便、快速、有效。     

法医常染色体STR分型

短串联重复序列 (ＳＴＲ)是广泛存在于人类基因组中的一类具有长度多态性的ＤＮＡ序列。它由 2～ 6个碱基对构成核心序列 ,呈串联重复排列 ,其长度多态性主要由核心序列拷贝数目的变化而产生。一般认为 ,人类基因组平均每 6～ 10ｋｂ就有 1个ＳＴＲ基因座 ,为法医个人识别和亲子鉴定提供了高信息基因座的丰富来源。与限制性片段长度多态性产生的ＤＮＡ指纹相比 ,用聚合酶链反应技术 (ＰＣＲ)扩增ＳＴＲ基因座产生的ＤＮＡ纹印具有更高的灵敏度。ＳＴＲ扩增片段较短 (10 0～ 30 0ｂｐ) ,对于常见含部分降解ＤＮＡ的陈旧斑痕 ,ＰＣＲ扩增ＳＴ…     

第三讲 法医DNA分型技术与方法

法医ＤＮＡ分型利用分子生物学技术检测、分析人类遗传标记 ,进行个体识别和亲子鉴定。 80年代以来 ,法医ＤＮＡ分型技术跨越了两大步 ,第一代分型是以ＤＮＡ分子杂交为核心的限制性片段长度多态性分析技术 ;第二代是以聚合酶链反应 (ＰＣＲ)为基础衍生出的各种ＤＮＡ标记分析技术。1　限制性片段长度多态性分析技术早年Ｊｅｆｆｒｅｙｓ建立的ＤＮＡ指纹技术本质是ＤＮＡ限制性片段长度多态性 (ＲＦＬＰ)分析 ,技术核心是ＤＮＡ分子杂交。ＤＮＡ指纹图谱的特异性取决于 2个因素 :一是限制性核酸内切酶特异性 ;二是探针特异性。ＲＦＬＰ分析…     

短串联重复vWFⅢ扩增片段长度多态性在法医学应用的可行性研究

目的 探讨ＳＴＲ位点ｖＷＦⅢ用于法医学鉴定中的实用价值。方法 应用聚合酶链式反应（ＰＣＲ），聚丙烯酰胺凝胶电泳结合染银显带的分离方法对ＳＴＲ位点ｖＷＦⅢ扩增片断长度多态性进行研究。结果 经过优化筛选掌握了该位点的最适扩增条件，其对各类检材均获得可靠的扩增产物。本方法的灵敏度达１０ｐｇ基因组ＤＮＡ、０．５μｌ全血、１μｌ新血痕、０．１μｌ精液、０．２μｌ新鲜精斑。结论 本方法快速、灵敏、准确，在法医     

线粒体DNA测序分析及其法医学应用

本文建立一种以γ－３２ＰＡＴＰ直接标记ＰＣＲ扩增引物为测序引物、纯化的ＰＣＲ扩增产物为模板、Ｔａｑ酶直接测序的方法、对１００倒无血缘关系的中国汉族人线粒体ＤＮＡ主要高变区Ｄ环区的３２８个碱基（第１６０９１－１６４１８位）进行了核酸序列分析，检出８６种基因型，出现率最高者为７％；检出８１个可变碱基位点。两个非血缘关系的中国汉族人出现完全相同序列的概率为０．００６８。通过对２个四代家系．５个三代家系和１０个两代家系分析扯实线粒体ＤＮＡ是母系遗传。     

降解的DNA的PCR分型—电洗脱回收大片断DNA法

本文分析了降解ＤＮＡ作ＰＣＲ分型易失败的原因，提出了因小片断ＤＮＡ过多，阻碍引物与膜板的复性及阻断引物延伸的新观点。将降解的ＤＮＡ电泳，切除小片断ＤＮＡ，电洗脱回收较大片断ＤＮＡ，成功地对降解ＤＮＡ进行了ＰＣＲ分型。本方法简便、快速、有效。     

用PCR-SSP法分析中国辽宁汉族HLA-DRB1基因多态性

应用ＰＣＲ－ＳＳＰ方法对辽宁地区１５９名无关个体进行ＨＬＡ－ＤＲＢ１位点基因分型，检出８组等位基因（扩增片段大小为１００ｂｐ），基因频率范围在０．０２２０１￣０．２３８９９，３６种可能基因型中检出３３种。经ｘ＾２检验符合Ｈａｒｄｙ－Ｗｅｉｎｂｅｒｇ平衡定律。本地区汉族群体的期望杂合度为８５％，观察杂合度为８３％，个人鉴别机率（ＤＰ）为０．９４，非父排除率（ＥＰＰ）为６６％，本法具有简单，快速，结果     

DNA分析技术在法科学中的应用及展望

本综述对ＤＮＡ指纹、ＰＣＲ－ＶＮＴＲ、ＰＣＲ－ＳＴＲ、ＰＣＲ－ｍｔＤＮＡ测序等技术的发展,以及其在法科学中的应用领域和发展前景作了系统的阐述。认为由于ＤＮＡ分析技术所具有特点,使之已成为责令法科学生物检材检验的主要手段之一。阐述了现阶段ＤＮＡ分析技术已向标准化、自动化和高鉴别机率方向发展,以及建立ＤＮＡ罪犯数据库的必要性和应用价值。     

避免生物检材PCR扩增失败的对策

ＰＣＲ是一种灵敏的ＤＮＡ检测技术，但是，在对生物学检材进行个人识别时，仍然有一定数量的检材直接ＰＣＲ扩增失败。为了有效地进行个人识别，本文分析了扩增失败的原因以及成功扩增的对策     

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。     

DNA甲基化在法医DNA分析中的应用

表观遗传学在生命的发生、发展过程中起着十分重要的作用。DNA甲基化作为表观遗传的一个重要方面,不仅参与多种基因的表达调控,与机体的发育、肿瘤发生等密切相关,而且具有可遗传性、相对稳定性、亲缘特异性、基因组中含量丰富等特点,已证实适用于法医DNA分析。本文对近年来DNA甲基化在印迹基因、同卵双生子鉴定、年龄、性别推断方面的研究与应用进行回顾与综述,以期为在法医学及相关领域中应用提供参考。     

DNA作证

基因时代到来以后,令各国政府头疼的犯罪问题可能会销声匿迹。为什么呢?因为那时的警察应用基因侦破技术,只要在现场发现很微小的罪犯遗留下的“基因线索”,就能得到罪犯完整的DNA序列,然后在人类基因资料库中轻而易举地查出罪犯……     

DNA Detectives

Credit-card-size devices will soon analyze DNA right at a crime scene identifying the perpetrators before they can strike again.     

Quantification of human mitochondrial DNA using synthesized DNA standards

Successful mitochondrial DNA (mtDNA) forensic analysis depends on sufficient quantity and quality of mtDNA. A real-time quantitative PCR assay was developed to assess such characteristics in a DNA sample, which utilizes a duplex, synthetic DNA to ensure optimal quality assurance and quality control. The assay's 105-base pair target sequence facilitates amplification of degraded DNA and is minimally homologous to nonhuman mtDNA. The primers and probe hybridize to a region that has relatively few sequence polymorphisms. The assay can also identify the presence of PCR inhibitors and thus indicate the need for sample repurification. The results show that the assay provides information down to 10 copies and provides a dynamic range spanning seven orders of magnitude. Additional experiments demonstrated that as few as 300 mtDNA copies resulted in successful hypervariable region amplification, information that permits sample conservation and optimized downstream PCR testing. The assay described is rapid, reliable, and robust.     

DNA profiling of trace DNA recovered from bedding

Trace DNA is often detected on handled items and worn clothing examined in forensic laboratories. In this study, the potential transfer of trace DNA to bedding by normal contact, when an individual sleeps in a bed, is examined. Volunteers slept one night on a new, lower bed sheet in their own bed and one night in a bed foreign to them. Samples from the sheets were collected and analysed by DNA profiling. The results indicate that the DNA profile of an individual can be obtained from bedding after one night of sleeping in a bed. The DNA profile of the owner of the bed could also be detected in the foreign bed experiments. Since mixed DNA profiles can be obtained from trace DNA on bedding, caution should be exercised when drawing conclusions from DNA profiling results obtained from such samples. This transfer may have important repercussions in sexual assault investigations.     

Validation issues around DNA typing of low level DNA

A recent ruling in the Crown Court of Northern Ireland, R v. Hoey, [R v Sean Hoey. 2007, Crown Court of Northern Ireland] has raised questions about the validity of one variant of DNA analysis, often termed LCN. The ruling and subsequent discussion also raises questions about what constitutes validation of a technique.This paper examines what can be achieved in a laboratory based validation study against the Daubert standard and against guidance given in the UK. There is a significant discrepancy between what can be achieved and the Daubert standard but much less of a discrepancy against the UK guidance. Much of the difference relates to differences in word usage, definitional difficulties, and a lack of mutual understanding and communication between the judiciary and forensic scientists. This highlights a gap that needs attention.     

Visualising DNA transfer: Latent DNA detection using Diamond Dye

A central question is ‘how did DNA get there’? To help answer this, we visually monitored and recorded DNA transfer from one substrate to another. When an individual touches a substrate, traces of their DNA are transferred (primary/direct) which can then subsequently be transferred to a second substrate (secondary/indirect). Currently DNA transfer and how much remains can only be determined by collecting the biological material from the substrate, isolating the DNA and quantifying the amount recovered. However, Diamond™ Dye (DD) enables such DNA transfer events to be visualised by monitoring the movement of cellular material.We examined primary and secondary DNA transfer using aluminium as a primary substrate with cotton, polyester, aluminium and plastic as secondary substrates and four contact types between two substrates (passive, pressure, friction and friction with pressure). Participants pressed their index finger against the aluminium for 15 s and then DD was applied to the area of contact; cellular material was detected via a fluorescence microscope. Contact between that substrate and a second substrate was performed, using one of the four contact types. After this contact between substrates each was viewed microscopically and transfer of cellular material was recorded.Cellular material could be recorded as having transferred from one substrate to another. Substrate and contact type had an effect on the extent DNA transfers. DNA transferred at a high rate with aluminium as a primary substrate and cotton, polyester and aluminium as secondary substrates when pressure with friction was applied. This information expands our understanding of how DNA transfers and which factors affect it, thus assisting greatly with activity level reporting as to how DNA came to be where it was found.