复合扩增mtDNA-HVI和Cyt b片段鉴定混合血痕种属

目的探讨mtDNA-HVI和Cyt b片段复合扩增法鉴定人与动物混合血痕种属的应用价值。方法用chelex-100法从人、牛、猪、狗、兔、鱼、鸡和鼠血痕中提取DNA,复合扩增mtDNA-HVI片段和Cyt b片段,琼脂糖凝胶电泳检测。结果人类在mtDNA-HVI区和Cyt b区分别出现279bp和358bp各一条带,且279bp条带亮于358bp;动物均只有358bp一条带。人与7种动物血痕的检测灵敏度均为3.13ng。检测人与动物混合DNA,灵敏度仍为3.13ng,但358bp条带亮于279bp条带。结论当358bp带明显强于279bp带时,提示检材为人与动物的混合。     

人线粒体DNA序列分析在法医学中的应用研究及其进展

综述人线粒体DNA(m tDNA)序列分析在法医学种属鉴别、个体识别,以及个体年龄推断中的应用研究及其进展,展望对m tDNA异质性的研究及建立人m tDNA数据库,并具有重要的法医学实践意义。     

小鼠骨骼肌细胞核DNA降解与死亡时间的关系

目的　监测小鼠死后骨骼肌核内DNA降解的情况 ,探讨死后细胞核DNA降解的一般规律。方法　建立小鼠死亡模型 ,在死后 72h内 ,以 12h的间隔取骨骼肌样本进行单细胞凝胶电泳 ,在荧光显微镜下测量彗星图像 ,并作统计学分析。结果　机体死后 ,骨骼肌细胞在电泳图像上出现了明显的彗星形拖尾 ,L/W比值随死亡时间而逐渐增大 ,二者呈一定的线性关系。结论　单细胞凝胶电泳技术可以应用于早期死亡时间推断。     

Bounding the number of contributors to mixed DNA stains

We derive a simple inequality for the probability of observing a given DNA profile when assuming a fixed number of unknown persons have contributed to the mixed stain. We then show how this inequality can be used to obtain an upper bound for the number of unknown contributors needed to be considered.     

畜禽空肠弯杆菌分离培养的影响因素

比较观察了空肠弯杆菌分离培养中微需氧法、培养时间、采样时机、运送时间、运送培养基、增菌培养法以及噻孢霉素和头孢哌酮钠等因素对该菌检出率的影响。结果表明 ,在 10 0mL/LCO2 气体环境中微需氧培养比烛缸内培养空肠弯杆菌检出率高 13 .0 % ,即显示 10 0mL/LCO2 法明显优于烛缸法 (P <0 .0 1) ;空肠弯杆菌分离培养时间以 48h即可 ,无须延长培养时间 ;产蛋鸡采样时机为产蛋前 ;检样运送时间、运送培养基和增菌培养后对空肠弯杆菌检出率的影响不明显(P >0 .0 5 ) ,用单一的一种分离培养方法不能反映动物的实际带菌水平 ;噻孢霉素对空肠弯杆菌检出率的影响和抗生素药敏性试验结果表明 ,噻孢霉素不能替代头孢霉素Ⅰ ,而头孢哌酮钠可取代Camp BAP琼脂中的头孢霉素Ⅰ。     

犬细小病毒JL-(18)1/Beagle株的分离鉴定及遗传进化分析

为研究犬细小病毒(CPV)流行株遗传变异情况,本研究从吉林省某比格犬养殖场采集疑似CPV感染致死犬的肠道组织,将病料接种至F81细胞进行病毒分离,并通过电镜形态学、PCR、血凝试验及动物回归试验进行鉴定。结果显示,所分离的这株病毒在F81细胞中产生了典型CPV细胞病变(CPE);在电镜下可见病毒呈无囊膜、直径为20 nm左右的病毒粒子;PCR鉴定证实CPV核酸呈阳性;血凝试验表明此病毒对猪红细胞具有凝集作用,血凝效价为1∶256;将这株病毒命名为JL-(18)1/Beagle。动物回归试验表明,JL-(18)1/Beagle使比格犬产生犬细小病毒感染的典型临床症状;以NS1基因进行遗传进化分析显示,JL-(18)1/Beagle与CPV-2c型分离株CPV-SH1516以及Canine/China/23/2017 NS1基因亲缘关系较近,而核苷酸相似率为100%;以VP2基因进行遗传进化分析显示,JL-(18)1/Beagle与New CPV-2b型CPV/CN/JL3/2013、CPV/CN/HB1/2013和CPV/CN/JL6/2013亲缘关系较近,核苷酸相似率为99.89%~99.94%;以VP2蛋白氨基酸进行序列分析表明,JL-(18)1/Beagle属于New CPV-2b型,与近期吉林CPV分离株相比,关键氨基酸位点无明显变化。因此,本试验从吉林省比格犬肠组织中分离到1株New CPV-2b型CPV毒株。     

DNA指纹的个体特异性和细胞稳定性研究

人类基因组的许多高度可变区域能够与小卫星探针杂交,而同时被检测出来,小卫星探针由串联重复的"核心"顺序构成.采用Southern印迹杂交获得的DNA指纹图包含多条高度可变的DNA片段杂交带,这些带主体细胞和生殖细胞中都表现出稳定性,而且安全具有个体特异性.本文用小卫星探针33.15,调查了北京地区的60名无关个体,     

Touch DNA collection from improvised explosive devices: A comprehensive study of swabs and moistening agents

Improvised explosive devices (IEDs) are used in devastating terrorist attacks worldwide and daily in Thailand. Touch DNA deposited during IED assembly are subjected to intense heat and pressure, resulting in rare events of usable DNA profiles obtained from real casework. No study has simultaneously evaluated both swab brands and moistening agents for touch DNA collection from substrates encountered in IED evidence. In this study, we investigated the effects of swab brands and moistening agents on DNA collection from adhesive tape, a common IED substrate. A full factorial design using four cotton swab brands (two forensic and two medical cotton swabs) and six moistening agents (DNA-free water, phosphate-buffered saline, ethanol, sodium dodecyl sulfate, isopropanol, and lysis buffer) was employed (24 total combinations). Using buffy coats, we found that DNA recovery depended on both swab brands and moistening agents (p < 0.05). The optimal method recovered significantly higher DNA amount from real IED cases compared to the standard Royal Thai Police method. Percentages of high partial profiles also increased. Our results changed the standard operating protocol of the Thai police. Other commonly found substrates from IED cases are being investigated to maximize the evidential value obtained from touch DNA.     

Estimating Individual Contributions to Complex DNA SNP Mixtures.,

High‐throughput sequencing (HTS) of large panels of single nucleotide polymorphisms (SNPs) provides an alternative or complimentary approach to short tandem repeats (STRs) panels for the analysis of complex DNA mixture forensic samples. For STRs, methods to estimate individual contribution concentrations compare capillary electrophoresis peak heights, peak areas, or HTS allele read counts within a mixture. This article introduces three approaches (mean, median, and slope methods) for estimating individual DNA contributions to forensic mixtures for HTS/massively parallel sequencing (MPS) SNP panels. For SNPs, the major:minor allele ratios or counts, unique to each contributor, were compared to estimate contributor proportion within the mixture using the mean, median, and slope intercept for these alleles. The estimates for these three methods were typically within 5% of planned experimental contributions for defined mixtures.     

The CSI Effect and the impact of DNA evidence on mock jurors and jury deliberations

ABSTRACT

The present research examined the CSI Effect and the impact of DNA evidence on mock jurors and jury deliberations using a 3 (Crime Drama Viewing: low, moderate, high)?×?3 (Evidence: DNA innocent, DNA guilty, no DNA control) design. A sample of 178 jury-eligible college students read a case of breaking and entering. Pre-deliberation, some support for a CSI Effect was found with high viewers’ extent of guilt ratings significantly lower than moderate and low viewers’ in the no DNA control and the DNA innocent conditions. This effect was not present for verdicts. Contrary to a CSI Effect, crime drama viewing was not related to guilt judgments with incriminating DNA evidence. A content analysis of comments made during deliberations found little support for the CSI Effect entering the jury room. Specifically, CSI Effect predictions were not supported when examining the discussion of DNA evidence, expressing DNA opinions, or mentioning missing evidence. Overall, the limited CSI Effect found for individuals was attenuated during deliberation. The alarm raised over a possible CSI Effect influencing jury decision making may be unwarranted.