实时荧光定量PCR检测硅藻UPA基因在溺死诊断中的研究

目的建立硅藻UPA条形码基因的实时荧光定量PCR检测方法,探讨其在溺死诊断中的应用价值。方法对Gene Bank中登录的硅藻UPA基因序列进行比对获得同源序列,据其设计硅藻门通用引物。对2种人体常见共生菌(大肠杆菌、双歧杆菌)、3种浮游细菌、15种浮游藻类、32具尸体(其中生前溺水死亡28例,死后抛尸1例,陆地死亡3例)的组织样本(肺、肝、肾)及尸体发现地水样提取DNA,采用设计的引物进行特异性、灵敏度、重复性试验,分析检材中硅藻检出情况,统计硅藻阳性率,以上述组织样本的微波消解-真空抽滤-自动扫描电镜法检测结果对建立的q PCR检测方法进行比较评估,比较该方法与PCR-毛细管电泳检测法的灵敏度。结果引物UPA99仅对硅藻标准株(针杆藻、舟形藻、直链藻、小环藻、菱形藻)DNA具有扩增,扩增产物熔解曲线平稳,峰尖且窄,熔解温度为(87±1)℃。以p MD18-T重组质粒为标准品,检测区间为1.56×10~2-1.56×10^-5ng/μL,建立实时q PCR方法的灵敏度为1.56×10^-5ng/μL,而PCR-CE方法的灵敏度为1.56×10-3ng/μL。批间及批内变异系数均低于2%,具有较高的重复性和稳定性。对于生前溺水尸体肺、肝、肾的检出率依次为89.3%,71.4%,64.3%。结论基于硅藻UPA基因设计通用引物,建立的q PCR硅藻检验法特异性高、灵敏度高、重复性好,应用于溺死诊断具有较好的应用前景。     

乳牛布鲁氏菌病PCR诊断试剂盒的实验室评估

对前期研制的布鲁氏菌omp25基因-PCR试剂盒的保存期、特异性和可重复性进行了测定,并应用该试剂盒对采自宁夏、甘肃、内蒙古、山西、黑龙江、新疆省(区)的98头血清凝集试验(SAT)阳性乳牛的6批98份乳样和350头SAT阴性乳牛的2批350份乳样进行了检测。检测结果显示,PCR试剂盒与SAT的阳性符合率为100%(98/98),阴性符合率为97.71%(342/350);从SAT阴性乳牛的乳样中,用PCR试剂盒检出8份阳性,表明其敏感性高于SAT;对2株田间野毒Br-gs和Br-nmg株进行了克隆与测序,二者与标准菌株序列的同源性分别为99.8%和100%。试验结果证实,本试剂盒的可重复性良好,特异性较高,-20℃下的有效保存期为5个月。     

伪狂犬病病毒gE/gB PCR鉴别方法的建立及其应用

为了检测伪狂犬病病毒(PRV)潜伏感染及确定病毒潜伏的主要部位,建立了能鉴别PRV野毒株和gE基因缺失疫苗株gE/gB的PCR诊断方法。结果表明,所建立的PCR 特异性强、敏感性高、稳定性好,能用于病毒潜伏感染的检测;同时还确定PRV潜伏感染的主要部位是三叉神经节、扁桃体、嗅球、脑干、脑桥和咽黏膜。     

中国鄂温克族人群15个STR基因座多态性研究

目的调查15个STR基因座在中国鄂温克族人群中的基因频率分布。方法应用PowerPlex16System复合扩增系统,对99名鄂温克族无关个的血样DNA进行多态性研究。结果在鄂温克族人群中15个STR基因座偶合率(Pm)在0.0205～0.1733之间,个体识别概率(DP)在0.8267～0.9795之间,杂合度在0.6061～0.9091之间,三联非父排除率(PE)在0.4038～0.7690之间,多态性信息总量(PIC)在0.5985～0.8734之间,15个STR基因座总TDP值为0.9999999999998,所有基因座经χ2检验符合Hard-Weinberg平衡。结论上述15个STR基因座在鄂温克族人群中等位基因分布较好,个体识别率高,适合法医个体识别和亲子鉴定。     

烟蒂DNA分型的研究

目的 研究烟蒂中DNA提取及其检验。方法 用Chelex-100法提取170枚烟蒂样本的DNA,进行PCR扩增及STR检验。结果 除1名志愿者提供的21枚烟蒂外层纸未能检出STR基因分型外,其余烟蒂外层纸均得到分型结果。加入少许烟丝的样本未能检出STR分型,与口唇接触的海绵有时可检出基因型,6个月内的烟蒂可检出小片段基因座。结论 烟蒂能进行DNA分型,在法医检案中具有应用价值。     

陈旧骨骼及牙齿的性别检验

为分析陈旧骨骼及牙齿的性别，建立了从陈旧人骨骼和牙齿中提出DNA的方法。通过PCR技术扩增，得到X－Y染色体上的单拷贝同源基因片断（AmelogeninGene）。结果显示，从死亡后2年、4年、7年和10年的4个骨骼和牙齿样品中，均成功地获得了特异的PCR扩增片段。女性为单一的106bp条带，男性为106bp和112bp两条谱带。其快速、简单、可靠，为陈旧骨骼和牙齿的性别鉴定提供了方法。     

复合扩增STR位点片段长度多态性的研究

本文介绍了以三个短串联重复序列（STR）位点为基础的复合扩增进行个体识别的技术。其特点是在同一扩增体系内对彼此独立的三个STR位点，即HUMTH01[AATG]nHUMFABP[AAT]nHUMARA[AGC]n进行复会扩增，扩增产物用聚丙烯酰胺凝胶电泳分离。经研究发现这三个STR位点具有高度多态性，扩增产物分子量在190～310bP之间，各位点等位基因数分别为6、9、16个，杂合度78．2％、85，0％、89．0％，个体识别率0．918、0．960、0．905，其累积的个体识别率达0．9997，高于pMCT118等位点，且扩增时间短，操作简便，为法医物证检验提供了一种高效的个体识别手段。     

A systematic approach to improve downstream single-cell analysis for the DEPArray™ technology

Most commercially available STR amplification kits have never been fully validated for low template DNA analysis, highlighting the need for testing different PCR kits and conditions for improving single-cell profiling. Here, current strategies rely mainly on adjusting PCR cycle number and analytical threshold settings, with a strong preference for using 30 amplification cycles and thresholds at 30–150 RFU for allele detection. This study aimed to (1) determine appropriate conditions for obtaining informative profiles utilizing a dilution series, and (2) test the outcome on single cells using the DEPArray™ technology. Four routinely applied forensic STR kits were compared by using three different amplification volumes and DNA dilutions down to 3.0 pg, while two well-performing kits were used for single/pooled leucocyte and sperm cell genotyping. Besides reduced costs, the results demonstrate that a 50%–75% PCR volume reduction was beneficial for peak height evaluation. However, this was counteracted by an increased artifact generation in diluted DNA volumes. Regarding profile completeness, the advantage of volume reduction was only prominent in samples processed with Fusion 6C. For single and pooled cells, ESIFast and NGMDetect provided a solid basis for consensus profiling regarding locus failure, although locus dropouts were generally observed as stochastic events. Amplification volume of 12.5 μL was confirmed as appropriate in terms of peak heights and stutter frequencies, with increased stutter peaks being the main artifact in single-cell profiles. Limitations associated with these analyses are discussed, providing a solid foundation for further studies on low template DNA.     

奶牛乳房炎四种致病菌PCR核酸免疫层析试纸条快速检测方法的建立及应用

为了开发检测导致奶牛乳房炎的无乳链球菌、金黄色葡萄球菌、大肠杆菌和停乳链球菌这四种重要致病菌的PCR核酸免疫层析试纸条方法,本研究采用柠檬酸还原法制备10 nm的胶体金溶液,选用优化的10μL 1 mol/L碳酸钾溶液调节pH和5μL异硫氰酸荧光素抗体偶联金颗粒,并使用优化的封闭液(10%BSA、0.25%PEG2000、0.05%吐温-20、0.05%Triton-X100)进行封闭,将地高辛抗体和山羊抗鼠二抗分别喷涂在检测线和质控线上,烘干并组装成试纸条,进行细菌的纯培养物和鲜牛奶加样检测。结果显示,所制备的PCR核酸免疫层析试纸条和凝胶电泳均具有较好的特异性,最低检测限要比凝胶电泳高10倍,在模拟污染牛奶样品测试中,试纸条仍然具有很好的特异性且灵敏度比凝胶电泳的高。上述结果表明,本研究建立的PCR核酸免疫层析试纸条检测方法具有良好的临床应用潜力。     

Time‐dependent Expression of MMP‐2 and TIMP‐2 after Rats Skeletal Muscle Contusion and Their Application to Determine Wound Age

The ability to determine vitality and estimate the survival period after a wound is critical in routine forensic practice. The mRNA levels of MMP‐2 and TIMP‐2 were examined using quantitative real‐time RT‐PCR to determine the age of a wound. Furthermore, the colocalization of them with Macrophage Marker, respectively, was detected by double immunofluorescence, and a standardized rat model of skeletal muscle contusion was established. In the antemortem contused groups, a large number of macrophages showed positive staining for MMP‐2 and TIMP‐2, and the expression of MMP‐2 and TIMP‐2 mRNA increased sharply at 3 days postinjury, with relative quantities of 5.75 and 2.98. No samples in the other groups showed relative quantities of >5.75 and 2.98; therefore, relative quantities exceeding 5.75 and 2.98 were strongly indicated 3 days after contusion. In addition, there was a significant decrease in the relative quantity in the postmortem contused groups, indicating that they were useful for diagnosing vitality.