17个Y-STR基因座遗传结构及用于姓氏推断的价值

目的调查我国10个姓氏群体Y-STR的遗传结构,探讨其用于鉴定的价值。方法采用AB Y-Filer荧光检测试剂盒,选取我国占人口数量最多的10个姓氏(李、王、张、刘、陈、杨、赵、黄、周、吴),每个姓氏100名汉族男性个体,采用Y-Filer荧光检测试剂盒,检测17个Y-STR基因座的等位基因频率分布和单倍型多样性,计算其遗传距离并比较群体间差异。结果 10个姓氏间单倍型多样性与总的群体单倍型多样性无显著差异,姓氏间与姓氏内的单倍型随机匹配概率差异很小。分析共祖系数Fst以及Reynold’s遗传距离,10个姓氏间任意两个姓氏群体对应17个Y-STR的Fst值均小于0.01。结论中国汉族10个主要姓氏在大的范围内Y-STR不表现出姓氏特异性,不能用Y-STR进行姓氏推断。     

马鼻肺炎病毒双重PCR分型检测方法的建立

根据GenBank中登录的马鼻肺炎病毒1、4型(EHV1、EHV4)糖蛋白B(gB)基因特异保守序列(登录号分别为AY665713、AF030027.1),各设计1对引物,建立了同时分型检测EHV1、EHV4的双重PCR方法;确定其最佳工作条件,并对该方法进行了特异性和敏感性试验。结果显示,在EHV1、EHV4中分别扩增出265bp和537bp的特异性目的条带,而马流感病毒cDNA、马动脉炎病毒cDNA、马乙型脑炎病毒cDNA及马传染性贫血弱毒疫苗株cDNA均未扩增出任何条带。EHV1的DNA最低检出限为2.1pg,EHV4的最低检出限为15pg。表明本试验建立的方法具备很高的应用价值。     

兔出血症病毒与欧洲野兔综合征病毒复合RT-PCR检测方法的建立

为建立用于兔出血症病毒(RHDV)和欧洲野兔综合征病毒(EBHSV)诊断鉴别的快速检测方法,根据GenBank中的RHDV和EBHSV基因组序列,设计合成5条特异性引物和9条重叠延伸引物,分别以通过重叠延伸PCR人工合成的EBHSV VP60基因中359bp基因片段构建的重组质粒pGM-T-EBHSV和RHDV RT-PCR产物构建的pGM-T-RHDV为模板,经过反应条件的优化、敏感性试验和特异性试验,初步建立了RHDV和EBHSV的复合RT-PCR检测方法,并对20份临床样品和5份RHDV人工感染样品进行了检测。结果表明,建立的复合RT-PCR方法具有良好的特异性和敏感性,可分别扩增出RHDV和EBHSV的特异性目的片段192bp和335bp,对2种病毒的检测限度均可达到50copies的目的基因片段,兔巴氏杆菌、兔大肠杆菌和沙门氏菌核酸扩增均为阴性。样品检测结果显示,5份人工感染样品的RHDV检出率为100%,20份临床样品的RHDV检测为阴性。     

6个新的STR基因座复合扩增体系的建立及应用

目的构建6个常染色体STR基因座的荧光复合扩增体系,应用于法医学DNA检验。方法筛选6个STR基因座D4S2366、D3S3045、D18S1002、D20S481、D22S689、D4S2639,根据复合扩增要求设计引物并采用不同荧光染料进行标记,经过反复调整和优化,建立6基因座荧光复合扩增体系,并用该复合扩增体系对224名华东汉族无关个体进行分型,计算出常用法医遗传学参数。结果使用该荧光复合扩增体系,在224名华东汉族无关个体中,6个STR基因座D4S2366、D3S3045、D18S1002、D20S481、D22S689、D4S2639分别检出7、8、9、10、9、9个等位基因和21、26、21、23、28、32种基因型,基因型分布符合Hardy-Weinberg平衡。杂合度（H）分布为0.714～0.808,个体识别率（DP）为0.874～0.934,二联体非父排除率（PED）为0.310～0.453,三联体非父排除率（PET）为0.485～0.628,多态信息含量（PIC）为0.672～0.784,二联体累积非父排除率（CPED）为0.947689,三联体累积非父排除率（CPET）为0.993345,累积个人识别能力（CDP）为0.999999543。结论构建的荧光复合扩增体系具有较高的法医学应用价值,D4S2366等6个常染色体STR基因座在华东汉族群体中均具有高度多态性,可作为常规商品化试剂盒的有效补充,用于突变情形的亲权鉴定以及依据亲权指数值不能明确鉴定意见的亲权鉴定。     

SYBR GreenI实时荧光PCR技术在人类DNA定量中的应用

目的建立SYBR Green I实时荧光定量PCR技术在法医物证检验中的应用。方法应用SYBR Green I实时荧光定量PCR技术对各种生物检材进行定量分析,并在此基础上进一步分析STR。结果得到了实验的各种生物检材的准确定量。结论SYBRSYBR Green I实时荧光定量PCR技术是一种高效且廉价的检测基因拷贝数的方法,具有法医学应用价值。     

FTA卡直接扩增缓冲增强剂的研制

目的研制一种能够配合非直接扩增试剂应用的PCR缓冲增强剂,实现对FTA卡保存样本的直接扩增。方法基于常规STR复合扩增试剂盒的扩增体系及引物组,加入增强剂对FTA卡类样本进行直接扩增。结果获得样本STR分型结果清晰、完整、平衡性好,无明显抑制现象存在。结论所研制的FTA卡直扩增强剂能达到FTA卡保存样本的直接扩增检验要求,可应用于法医STR检验。     

Development of a real-time method to detect DNA degradation in forensic samples

Abstract: Knowledge of the degradation state of evidentiary DNA samples would allow selection of the appropriate analysis method (standard short tandem repeats [STRs] vs. mini STRs vs. mtDNA). This article describes the development of a Plexor® technology/real‐time PCR DNA degradation detection assay, which uses a common forward primer and two reverse primers (different fluorophores) to generate two Alu amplicons (63 and 246 bp). This very sensitive assay was optimized for reaction volume, cycle number, anneal/extend time, and temperature. Using DNA samples degraded with DNaseI, the ratio of the concentration of the short amplicon to the concentration of the long amplicon (degradation ratio) was increased versus time of degradation. Experiments were performed on a variety of environmentally degraded samples (age, sunlight, heat) and with seven commonly encountered forensic inhibitors. The degradation ratio was found to predict the observed loss of larger STR loci seen in the analysis of comprised samples.     

A stochastic model of the processes in PCR based amplification of STR DNA in forensic applications

In forensic DNA profiling use is made of the well-known technique of PCR. When the amount of DNA is high, generally unambiguous profiles can be obtained, but for low copy number DNA stochastic effects can play a major role. In order to shed light on these stochastic effects, we present a simple model for the amplification process. According to the model, three possible things can happen to an individual single DNA strand in each complete cycle: successful amplification, no amplification, or amplification with the introduction of stutter. The model is developed in mathematical terms using a recursive approach: given the numbers of chains at a given cycle, the numbers in the next can be described using a multinomial probability distribution. A full set of recursive relations is derived for the expectations and (co)variances of the number of amplicon chains with no, 1 or 2 stutters. The exact mathematical solutions of this set are given, revealing the development of the expectations and (co)variances as function of the cycle number. The equations reveal that the expected number of amplicon chains without stutter grows exponentially with the cycle number, but for the chains with stutter the relation is more complex. The relative standard deviation on the numbers of chains (coefficient of variation) is inversely proportional to the square root of the expected number of DNA strands entering the amplification. As such, for high copy number DNA the stochastic effects can be ignored, but they play an important role at low concentrations. For the allelic peak, the coefficient of variation rapidly stabilizes after a few cycles, but for the chains with stutter the decrease is more slowly. Further, the ratio of the expected intensity of the stutter peak over that of the allelic peak increases linearly with the number of cycles. Stochastic models, like the one developed in the current paper, can be important in further developing interpretation rules in a Bayesian context.     

AGCU免提取STR荧光检测试剂盒的验证

目的考察AGCU免提取STR荧光检测试剂盒．对保存在滤纸片或FTA卡上血液样本的直接扩增检测情况。方法使用人GCU免提取STR荧光检测试剂盒,对未经提取的滤纸片血液样本、FTA卡血液样本675份进行直接扩增和18个基因座的DNA分型,并对结果的可靠性进行研究。结果18个基因座检测结果与PP16和ID试剂盒分型结果一致,2000年数据库样本成功率92．3％,2001年数据库样本成功率92．6％,2004以后年数据样本及案件样本、亲子鉴定样本成功率在99％以上。结论AGCU试剂盒可以成功地对滤纸片、FTA卡样本的18个STR基因座进行直接扩增检测,检验结果稳定,分型准确。