A mixed DNA profile controversy revisited

Semaan et al. (J Forensic Res, 2020, 11, 453) discuss a mock case “where eight different individuals [P₁ through P₈] could not be excluded in a mixed DNA analysis. Even though … expert DNA mixture analysis software was used.” Two of these are the true donors. The LRs reported are incorrect due to the incorrect entry of propositions into LRmix Studio. This forced the software to account for most of the alleles as drop-in, resulting in LRs 60–70 orders of magnitude larger than expected. P₁, P₂, P₄, P₅, and P₈ can be manually excluded using peak heights. This has relevance when using LRmix which does not use peak heights. We extend the work using the same two reference genotypes who were the true contributors as Semaan et al. (J Forensic Res, 2020, 11, 453). We simulate three two-donor mixtures with peak heights using these two genotypes and analyze using STRmix?. For the simulated 1:1 mixture, one of the non-donors’ LRs supported him being a contributor when no conditioning was used. When considered in combination with any other potential donors (i.e., with conditioning), this non-donor was correctly eliminated. For the 3:1 mixture, all results correctly supported that the non-donors were not contributors. The low-template 4:1 mixture LRs with no conditioning showed support for all eight profiles as donors. However, the results from pair-wise conditioning showed that only the two ground truth donors had LRs supporting that they were contributors to the mixture. We recommend the use of peak heights and conditioning profiles, as this allows better sensitivity and specificity even when the persons share many alleles.     

应用硅珠法提取陈旧骨骼DNA

骨骼相对于人体其他的组织脏器腐败降解慢,是进行高度腐败及白骨化样本DNA检验的唯一检材。但骨骼DNA的提取比较困难,本文运用传统的硅珠法提取骨骼DNA取得了很好的效果。1材料与方法1.1样本1~4年水浸泡、土埋的股骨、肱骨等样本,来自本实验室日常检案检材。1.2方法1.2.1骨骼DNA提取用水洗净骨骼表面,晾干。锯成小块,用锉打磨内外表面。去离子水、乙醇和5%bleach浸泡、晾干,磨成粉末。取骨粉5g;加入0.5mon/L EDTA(pH8.0)溶液,搅拌均匀置于摇床上脱钙12h,去离子水洗两遍,去上清,重复4次[1];沉渣中加入适量裂解液(6mon/L GuSCN,20mo…     

百草枯中毒分析检测方法的研究进展

本文介绍了最近20年来国内外有关生物检材中百草枯的提取、净化及定性定量分析检测方法的研究进展,从而为进一步研究百草枯中毒的分析检验方法提供参考。     

DNA commission of the International Society of Forensic Genetics: Recommendations on the interpretation of mixtures

The DNA commission of the International Society of Forensic Genetics (ISFG) was convened at the 21st congress of the International Society for Forensic Genetics held between 13 and 17 September in the Azores, Portugal. The purpose of the group was to agree on guidelines to encourage best practice that can be universally applied to assist with mixture interpretation. In addition the commission was tasked to provide guidance on low copy number (LCN) reporting. Our discussions have highlighted a significant need for continuing education and research into this area. We have attempted to present a consensus from experts but to be practical we do not claim to have conveyed a clear vision in every respect in this difficult subject. For this reason, we propose to allow a period of time for feedback and reflection by the scientific community. Then the DNA commission will meet again to consider further recommendations.     

牛分枝杆菌esat-6和mpb70-mpb83基因DNA疫苗的免疫效果

用PCR技术和重叠延伸剪接技术获得牛分枝杆菌esat-6基因和mpb70-mpb83融合基因,连接真核表达载体pcDNA3.1(+),构建了重组质粒pCE6和pC70-83-E6。分4组免疫小鼠:pCE6组、pC70-83-E6组、pcDNA3.1(+)和PBS对照组,采用间接ELISA法检测免疫小鼠血清特异性抗体水平,MTT法检测免疫小鼠脾淋巴细胞增殖情况和IFN-γ分泌情况。结果表明,2重组质粒免疫组小鼠的血清抗体水平持续上升,而2对照组始终维持在较低水平,且pC70-83-E6组小鼠的抗体水平高于pCE6组。经PPD刺激后,pCE6组和pC70-83-E6组小鼠的SI值与2对照组均差异显著(P<0.05),2重组质粒免疫组间差异不显著(P>0.05);2重组质粒免疫小鼠脾细胞产生的IFN-γ均显著高于2对照组(P<0.05),且pC70-83-E6组明显高于其他3组(P<0.05)。证实本试验构建的2种牛分枝杆菌DNA疫苗可有效诱导实验动物产生体液免疫和细胞免疫应答。     

囊素对猪口蹄疫灭活疫苗的免疫增强作用

用提取的天然囊素(10μg/mL)和O型口蹄疫灭活疫苗协同免疫45日龄仔猪,研究了其对O型口蹄疫灭活疫苗免疫效果及仔猪增重的影响。将32头健康45日龄仔猪随机分为4组,0.5 mL疫苗 囊素免疫2次(Ⅰ)组1、.0 mL疫苗 囊素免疫2次(Ⅱ)组1、.0 mL疫苗 囊素免疫1次(Ⅲ)组和1.0 mL疫苗免疫2次(Ⅳ)组(疫苗对照组),用液相阻断酶联免疫吸附试验(LB-ELISA)检测各组猪免疫前及一免后第14、28、42、60、74、881、02 d的口蹄疫血清抗体效价并称重。结果,Ⅱ组抗体水平显著高于Ⅳ组(P<0.01),Ⅰ组、Ⅲ组和Ⅳ组间差异不显著(P>0.05);一免后第60~110 d仔猪平均日增重囊素组明显高于对照组(P<0.05)。结果表明,囊素可以提高口蹄疫灭活疫苗的免疫原性,提高猪增重,促进生长发育。     

细菌分型的分子生物学技术研究进展

回顾了传统细菌分型方法的重要作用,并重点介绍了近年发展得比较成熟的脉冲凝胶电泳(PF-GE)、低频限制性切割位点聚合酶链式反应(IRS-PCR)、随意扩增多态性DNA(RAPD)、扩增片段长度多态性(AFLP)、多位点酶电泳(MLEE)和多位点测序分型(MLST)等6种用于细菌分型的分子生物学技术的原理、特点以及应用情况,指出了其他细菌分型技术,如ARDRA、SSCP、DGGE、TGGEI、S等的不足,对基因芯片技术和实时PCR在细菌分型上的应用潜力进行了展望。     

Appeals to Reason

This article considers how statistical reasoning changes conceptions of evidence and proof. Beginning with three Court of Appeal judgments in which proof is quantified, it traces the implications of statistical ways of thinking about proof through the law of criminal evidence. This leads to the bizarre conclusion that proof is, by and large, impossible. The argument then takes a more constructive turn. The way in which the presumption of innocence is conceptualised in statistical argument is criticised and it is suggested that proof depends on a precondition of trust in the way suspects are selected by the police. For that trust to be deserved, police suspects must be chosen in a legitimate manner.     

用引物Y_3,Y_4和DNA扩增技术作血液(痕)和毛根性别鉴定的研究

作者用引物Y_3、Y_4和DNA聚合酶链式反应(PCR)作微量人类血液(痕)和毛根的性别鉴定。扩增的靶序列位于Y染色体DNA特异3.4kb重复序列中,扩增产物为460bp。检材用量为:新鲜血液0.5μl、血痕纱纤维1mm、毛根单个。20例保存4个月的血痕与2例保存6年半的血痕性别判定结果均正确,无性别记载的保存9～11年的3例血痕显现了清晰的460bpY特异DNA扩增带。15例保存20天的自然脱落毛根性别判定结果均正确。本法省略了检材处理中的酚-氯仿抽提DNA等纯化步骤,既简化了实验操作,又减少了检验过程中外源DNA的污染机会和样品DNA的损耗,使这一性别鉴定方法更符合法医学实践的需要。     

DNA技术侦破一特大系列强奸案

１案件资料近５年在沈阳市于洪区某地连续发生数十起强奸案，案犯体貌特征、作案手段相似，最显著的特征是“小平头”，因此将该系列案件称为“小平头”系列强奸案。该案引起了沈阳市各级公安部门的高度重视。１９９９年８月９日，“小平头”再次作案，将居住在于洪区的李某（女，１８岁）强奸。笔者对该案精斑进行９个STR位点的基因分型并存档，并以此为依据排除曹某等多名嫌疑人。２０００年７月５日，笔者对新发现的嫌疑人王某血样进行DNA鉴定，并与微机案件库中１９９９年８月９日李某被强奸案中精斑谱带比对，其结果见表１，表２．…